WorldWideScience

Sample records for situ composite solders

  1. Soldering of copper-clad niobium--titanium superconductor composite

    International Nuclear Information System (INIS)

    Moorhead, A.J.; Woodhouse, J.J.; Easton, D.S.

    1977-04-01

    When superconductivity is applied to various electrical devices, the joining of the superconducting material and the performance of the joints are generally crucial to the successful operation of the system. Although many techniques are being considered for joining composite superconductors, soldering is the most common. We determined the wetting and flow behavior of various solder and flux combinations on a copper-clad Nb-Ti composite, developed equipment and techniques for soldering and inspection of lap joints, and determined the shear strength of joints at temperatures down to -269 0 C (4 0 K). We studied 15 solders and 17 commercial and experimental fluxes in the wettability and flow tests. A resistance unit was built for soldering test specimens. A series of samples soldered with 80 Pb-20 Sn, 83 Pb-15 Sn-2 Sb, 97.5 Pb-1.5 Ag-1 Sn, 80 In-15 Pb-5 Ag, or 25 In-37.5 Pb-37.5 Sn (wt percent) was inspected by three nondestructive techniques. Through-transmission ultrasound gave the best correlation with nonbond areas revealed in peel tests. Single-lap shear specimens soldered with 97.5 Pb-1.5 Ag-1 Sn had the highest strength (10.44 ksi, 72 MPa) and total elongation (0.074 in., 1.88 mm) at -269 0 C (4 0 K) of four solders tested

  2. Bottom-up nanoarchitecture of semiconductor nano-building blocks by controllable in situ SEM-FIB thermal soldering method

    KAUST Repository

    Zhang, Xuan

    2017-08-10

    Here we demonstrate that the building blocks of semiconductor WO3 nanowires can be controllably soldered together by a novel nano-soldering technique of in situ SEM-FIB thermal soldering, in which the soldering temperature can precisely remain in an optimal range to avoid a strong thermal diffusion.

  3. Bottom-up nanoarchitecture of semiconductor nano-building blocks by controllable in situ SEM-FIB thermal soldering method

    KAUST Repository

    Zhang, Xuan; Zheng, Xiujun; Zhang, Hong; Zhang, Junli; Fu, Jiecai; Zhang, Qiang; Peng, Chaoyi; Bai, Feiming; Zhang, Xixiang; Peng, Yong

    2017-01-01

    Here we demonstrate that the building blocks of semiconductor WO3 nanowires can be controllably soldered together by a novel nano-soldering technique of in situ SEM-FIB thermal soldering, in which the soldering temperature can precisely remain in an optimal range to avoid a strong thermal diffusion.

  4. A new method for soldering particle-reinforced aluminum metal matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Jinbin; Mu, Yunchao [Zhongyuan University of Technology, Zhengzhou 450007 (China); Luo, Xiangwei [Zhengzhou University, Zhengzhou 450002 (China); Niu, Jitai, E-mail: niujitai@163.com [Zhongyuan University of Technology, Zhengzhou 450007 (China)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Soldering of 55% SiCp/Al composite and Kovar is first achieved in the world. Black-Right-Pointing-Pointer The nickel plating is required on the surface of the composites before soldering. Black-Right-Pointing-Pointer Low welding temperature is set to avoid overheating of the matrix. Black-Right-Pointing-Pointer Chemical and metallurgical bonding of composites and Kovar is carried out. Black-Right-Pointing-Pointer High tension strength of 225 MPa in soldering seam has been obtained. - Abstract: Soldering of aluminum metal matrix composites (Al-SiC) to other structural materials, or even to themselves, has proved unsuccessful mainly due to the poor wetting of these composites by conventional soldering alloys. This paper reports a new approach, which improves the wetting properties of these composites by molting solder alloys to promote stronger bonds. The new approach relies on nickel-plating of the composite's faying surface prior to application of a solder alloy. Based on this approach, an aluminum metal matrix composite containing 55 vol.% SiC particles is successfully soldered to a Fe-Ni-Co alloy (commercially known as Kovar 4J29). The solder material is a zinc-based alloy (Zn-Cd-Ag-Cu) with a melting point of about 400 Degree-Sign C. Microscopic examinations of the aluminum metal matrix composites (Al-MMCs)-Kovar interfaces show that the nickel-plating, prior to soldering, could noticeably enhance the reaction between the molten solder and composites. The fractography of the shear-tested samples revealed that fracture occurs within the composite (i.e. cohesive failure), indicating a good adhesion between the solder alloy and the Al-SiC composite.

  5. A new method for soldering particle-reinforced aluminum metal matrix composites

    International Nuclear Information System (INIS)

    Lu, Jinbin; Mu, Yunchao; Luo, Xiangwei; Niu, Jitai

    2012-01-01

    Highlights: ► Soldering of 55% SiCp/Al composite and Kovar is first achieved in the world. ► The nickel plating is required on the surface of the composites before soldering. ► Low welding temperature is set to avoid overheating of the matrix. ► Chemical and metallurgical bonding of composites and Kovar is carried out. ► High tension strength of 225 MPa in soldering seam has been obtained. - Abstract: Soldering of aluminum metal matrix composites (Al–SiC) to other structural materials, or even to themselves, has proved unsuccessful mainly due to the poor wetting of these composites by conventional soldering alloys. This paper reports a new approach, which improves the wetting properties of these composites by molting solder alloys to promote stronger bonds. The new approach relies on nickel-plating of the composite's faying surface prior to application of a solder alloy. Based on this approach, an aluminum metal matrix composite containing 55 vol.% SiC particles is successfully soldered to a Fe–Ni–Co alloy (commercially known as Kovar 4J29). The solder material is a zinc-based alloy (Zn–Cd–Ag–Cu) with a melting point of about 400 °C. Microscopic examinations of the aluminum metal matrix composites (Al-MMCs)–Kovar interfaces show that the nickel-plating, prior to soldering, could noticeably enhance the reaction between the molten solder and composites. The fractography of the shear-tested samples revealed that fracture occurs within the composite (i.e. cohesive failure), indicating a good adhesion between the solder alloy and the Al–SiC composite.

  6. Influence of Co and W powders on viscosity of composite solders during soldering of specially shaped diamond-abrasive tools

    Science.gov (United States)

    Sokolov, E. G.; Aref’eva, S. A.; Svistun, L. I.

    2018-03-01

    The influence of Co and W powders on the structure and the viscosity of composite solders Sn-Cu-Co-W used for the manufacture of the specially shaped diamond tools has been studied. The solders were obtained by mixing the metallic powders with an organic binder. The mixtures with and without diamonds were applied to steel rollers and shaped substrates. The sintering was carried out in a vacuum at 820 ° C with time-exposure of 40 minutes. The influence of Co and W powders on the viscosity solders was evaluated on the basis of the study of structures and according to the results of sintering specially shaped diamond tools. It was found that to provide the necessary viscosity and to obtain the uniform diamond-containing layers on the complex shaped surfaces, Sn-Cu-Co-W solder should contain 27–35 vol % of solid phase. This is achieved with a total solder content of 24–32 wt % of cobalt powder and 7 wt % of tungsten powder.

  7. In situ TEM observation of microcrack nucleation and propagation in pure tin solder

    International Nuclear Information System (INIS)

    Ding Ying; Wang Chunqing; Li, Mingyu; Wang Weiqiang

    2006-01-01

    Microcrack nucleation and propagation behavior in pure tin solder was investigated by using transmission electron microscopy (TEM) through in situ tensile test. Observation results showed that fracture process was completed in this visco-plastic material by connecting discontinuous cracks or voids. Depending on remarkable vacancy diffusion ability, microvoids were nucleated and developed in the dislocation free zone (DFZ) or super thinned area ahead of crack tip under local high stress concentration. The cracks were linked with each other by mutual dislocation emission which expedites the propagation of crack tips effectively

  8. SMT soldering handbook

    National Research Council Canada - National Science Library

    Strauss, Rudolf

    1998-01-01

    ... 3.2.1 Constituents, melting behaviour and mechanical properties 3.2.2 Composition of solders for use in electronics 3.2.3 Lead-free solders 3.2.4 Solder impurities The soldered joint 3.3.1 Solde...

  9. In situ investigation of SnAgCu solder alloy microstructure

    International Nuclear Information System (INIS)

    Pietrikova, Alena; Bednarcik, Jozef; Durisin, Juraj

    2011-01-01

    Research highlights: → In situ X-ray diffraction investigation enabled detailed analysis of the melting and solidification process of the SAC305 alloy. → It was found that the SAC305 solder melts at 230 deg. C. When cooling from 240 deg. C the SAC305 alloy solidifies at the temperature of 214 deg. C. During solidification β-Sn and Cu 6 Sn 5 is also formed. Formation of Ag 3 Sn occurs at 206 deg. C and the remaining amount of alloy crystallizes approximately at 160 deg. C. → Furthermore, observation of the thermal expansion behaviour of the β-Sn tetragonal unit cell revealed linear dependence of the unit cell volume on temperature. The unit cell parameters a and c also increase linearly with the temperature. Despite the fact that the c parameter is substantially smaller than parameter a, it exhibits a significantly higher linear thermal expansion coefficient. Comparison between data obtained during heating and cooling indicates that the thermal expansion coefficient is slightly greater in the case of cooling. - Abstract: In situ X-ray diffraction experiments, using synchrotron radiation, were employed to analyze microstructure evolution of the 96.5Sn3Ag0.5Cu (wt.%)-SAC305 lead-free solder alloy during heating (30-240 deg. C), isothermal dwell (240 deg. C) and cooling (240-30 deg. C). The special emphasis was placed on the study of the melting and solidification processes, explaining formation, distribution and the order of crystallization of the crystal phases (β-Sn, intermetallic compounds) in the solder alloy. Furthermore, thermal expansion behaviour of the main constituent phase β-Sn was analyzed prior to melting and after the consequent solidification.

  10. In-situ Investigation of Lead-free Solder Alloy Formation Using a Hot-plate Microscope

    DEFF Research Database (Denmark)

    Bergmann, René; Tang, Peter Torben; Hansen, Hans Nørgaard

    2007-01-01

    This work presents the advantages of using a hot-plate microscope for investigation of new (high-temperature) lead- free solders as in-situ analysis tool and preparation equipment. A description of the equipment and the preparation method is given and some examples are outlined. The formation...

  11. Creep deformation behavior in eutectic Sn-Ag solder joints using a novel mapping technique

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, J.P.; Guo, F.; McDougall, J.; Bieler, T.R.; Subramanian, K.N.; Park, J.K.

    1999-11-01

    Creep deformation behavior was measured for 60--100 {micro}m thick solder joints. The solder joints investigated consisted of: (1) non-composite solder joints made with eutectic Sn-Ag solder, and (2) composite solder joints with eutectic Sn-Ag solder containing 20 vol.%, 5 {micro}m diameter in-situ Cu{sub 6}Sn{sub 5} intermetallic reinforcements. All creep testing in this study was carried out at room temperature. Qualitative and quantitative assessment of creep deformation was characterized on the solder joints. Creep deformation was analyzed using a novel mapping technique where a geometrical-regular line pattern was etched over the entire solder joint using excimer laser ablation. During creep, the laser-ablation (LA) pattern becomes distorted due to deformation in the solder joint. By imaging the distortion of laser-ablation patterns using the SEM, actual deformation mapping for the entire solder joint is revealed. The technique involves sequential optical/digital imaging of the deformation versus time history during creep. By tracing and recording the deformation of the LA patterns on the solder over intervals of time, local creep data are obtained in many locations in the joint. This analysis enables global and localized creep shear strains and strain rate to be determined.

  12. Soldering handbook

    CERN Document Server

    Vianco, Paul T

    1999-01-01

    Contains information related to soldering processes, and solder joint performance and reliability. Covers soldering fundamentals, technology, materials, substrate materials, fluxes, pastes, assembly processes, inspection, and environment. Covers today's advanced joining applications and emphasizes new materials, including higher strength alloys; predictive performance; computer modeling; advanced inspection techniques; new processing concepts, including laser heating; and the resurgence in ultrasonic soldering.

  13. Effects of Metallic Nanoparticles on Interfacial Intermetallic Compounds in Tin-Based Solders for Microelectronic Packaging

    Science.gov (United States)

    Haseeb, A. S. M. A.; Arafat, M. M.; Tay, S. L.; Leong, Y. M.

    2017-10-01

    Tin (Sn)-based solders have established themselves as the main alternative to the traditional lead (Pb)-based solders in many applications. However, the reliability of the Sn-based solders continues to be a concern. In order to make Sn-based solders microstructurally more stable and hence more reliable, researchers are showing great interest in investigating the effects of the incorporation of different nanoparticles into them. This paper gives an overview of the influence of metallic nanoparticles on the characteristics of interfacial intermetallic compounds (IMCs) in Sn-based solder joints on copper substrates during reflow and thermal aging. Nanocomposite solders were prepared by mechanically blending nanoparticles of nickel (Ni), cobalt (Co), zinc (Zn), molybdenum (Mo), manganese (Mn) and titanium (Ti) with Sn-3.8Ag-0.7Cu and Sn-3.5Ag solder pastes. The composite solders were then reflowed and their wetting characteristics and interfacial microstructural evolution were investigated. Through the paste mixing route, Ni, Co, Zn and Mo nanoparticles alter the morphology and thickness of the IMCs in beneficial ways for the performance of solder joints. The thickness of Cu3Sn IMC is decreased with the addition of Ni, Co and Zn nanoparticles. The thickness of total IMC layer is decreased with the addition of Zn and Mo nanoparticles in the solder. The metallic nanoparticles can be divided into two groups. Ni, Co, and Zn nanoparticles undergo reactive dissolution during solder reflow, causing in situ alloying and therefore offering an alternative route of alloy additions to solders. Mo nanoparticles remain intact during reflow and impart their influence as discrete particles. Mechanisms of interactions between different types of metallic nanoparticles and solder are discussed.

  14. In-situ study of electromigration-induced grain rotation in Pb-free solder joint by synchrotron microdiffraction

    International Nuclear Information System (INIS)

    Chen, Kai; Tamura, Nobumichi; Tu, King-Ning

    2008-01-01

    The rotation of Sn grains in Pb-free flip chip solder joints hasn't been reported in literature so far although it has been observed in Sn strips. In this letter, we report the detailed study of the grain orientation evolution induced by electromigration by synchrotron based white beam X-ray microdiffraction. It is found that the grains in solder joint rotate more slowly than in Sn strip even under higher current density. On the other hand, based on our estimation, the reorientation of the grains in solder joints also results in the reduction of electric resistivity, similar to the case of Sn strip. We will also discuss the reason why the electric resistance decreases much more in strips than in the Sn-based solders, and the different driving force for the grain growth in solder joint and in thin film interconnect lines

  15. In-situ study of electromigration-induced grain rotation in Pb-free solder joint by synchrotron microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Kai; Tamura, Nobumichi; Tu, King-Ning

    2008-10-31

    The rotation of Sn grains in Pb-free flip chip solder joints hasn't been reported in literature so far although it has been observed in Sn strips. In this letter, we report the detailed study of the grain orientation evolution induced by electromigration by synchrotron based white beam X-ray microdiffraction. It is found that the grains in solder joint rotate more slowly than in Sn strip even under higher current density. On the other hand, based on our estimation, the reorientation of the grains in solder joints also results in the reduction of electric resistivity, similar to the case of Sn strip. We will also discuss the reason why the electric resistance decreases much more in strips than in the Sn-based solders, and the different driving force for the grain growth in solder joint and in thin film interconnect lines.

  16. Development of Bi-base high-temperature Pb-free solders with second-phase dispersion: Thermodynamic calculation, microstructure, and interfacial reaction

    Science.gov (United States)

    Takaku, Yoshikazu; Ohnuma, Ikuo; Kainuma, Ryosuke; Yamada, Yasushi; Yagi, Yuji; Nishibe, Yuji; Ishida, Kiyohito

    2006-11-01

    Bismuth and its alloys are candidates for Pb-free high-temperature solders that can be substituted for conventional Pb-rich Pb-Sn solders (melting point (mp) = 573 583 K). However, inferior properties such as brittleness and weak bonding strength should be improved for practical use. To that end, BiCu-X (X=Sb, Sn, and Zn) Pb-free high-temperature solders are proposed. Miscibility gaps in liquid BiCu-X alloys were surveyed using the thermodynamic database ADAMIS (alloy database for micro-solders), and compositions of the BiCu-X solders were designed on the basis of calculation. In-situ composite solders that consist of a Bi-base matrix with fine intermetallic compound (IMC) particles were produced by gas-atomizing and melt-spinning methods. The interfacial reaction between in-situ composite solders and Cu or Ni substrates was investigated. The IMCs at the interface formed a thin, uniform layer, which is an appropriate morphology for a reliable solder joint.

  17. Processing and Characterization of NiTi Shape Memory Alloy Particle Reinforced Sn-In Solders

    National Research Council Canada - National Science Library

    Chung, Kohn C

    2006-01-01

    .... In previous work, it was proposed that reinforcement of solder by NiTi shape memory alloy particles to form smart composite solder reduces the inelastic strain of the solder and hence, may enhance...

  18. In situ measurement of electromigration-induced transient stress in Pb-free Sn-Cu solder joints by synchrotron radiation based X-ray polychromatic microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Kai; Tamura, Nobumichi; Kunz, Martin; Tu, King-Ning; Lai, Yi-Shao

    2009-12-01

    Electromigration-induced hydrostatic elastic stress in Pb-free SnCu solder joints was studied by in situ synchrotron X-ray white beam microdiffraction. The elastic stresses in two different grains with similar crystallographic orientation, one located at the anode end and the other at the cathode end, were analyzed based on the elastic anisotropy of the Beta-Sn crystal structure. The stress in the grain at the cathode end remained constant except for temperature fluctuations, while the compressive stress in the grain at the anode end was built-up as a function of time during electromigration until a steady state was reached. The measured compressive stress gradient between the cathode and the anode is much larger than what is needed to initiate Sn whisker growth. The effective charge number of Beta-Sn derived from the electromigration data is in good agreement with the calculated value.

  19. In situ measurement of electromigration-induced transient stress in Pb-free Sn-Cu solder joints by synchrotron radiation based X-ray polychromatic microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Kai; Tamura, Nobumichi; Kunz, Martin; Tu, King-Ning; Lai, Yi-Shao

    2009-05-15

    Electromigration-induced hydrostatic elastic stress in Pb-free SnCu solder joints was studied by in situ synchrotron X-ray white beam microdiffraction. The elastic stresses in two different grains with similar crystallographic orientation, one located at the anode end and the other at the cathode end, were analyzed based on the elastic anisotropy of the {beta}-Sn crystal structure. The stress in the grain at the cathode end remained constant except for temperature fluctuations, while the compressive stress in the grain at the anode end was built-up as a function of time during electromigration until a steady state was reached. The measured compressive stress gradient between the cathode and the anode is much larger than what is needed to initiate Sn whisker growth. The effective charge number of {beta}-Sn derived from the electromigration data is in good agreement with the calculated value.

  20. Spontaneous soldering

    International Nuclear Information System (INIS)

    Percacci, R.

    1984-01-01

    It is proposed that the soldering form of general relativity be treated as a dynamical variable. This gives rise to the possibility of treating the linear connection on (n-dimensional) spacetime and an internal O(k)-Yang-Mills field as different components of the same O(N) gauge field (N= n+k). The distinction between gravitational and Yang-Mills interactions is due to a kind of Higgs mechanism driven by the vacuum expectation value of the soldering form. (orig.)

  1. Methodology for Analyzing Strain States During In-Situ Thermomechanical Cycling in Individual Lead Free Solder Joints Using Synchrotron Radiation

    International Nuclear Information System (INIS)

    Zhou, Bite; Bieler, Thomas R.; Lee, Tae-Kyu; Liu, Kuo-Chuan

    2009-01-01

    To examine how a lead-free solder joint deforms in a thermal cycling environment, both the elastic and plastic stress and strain behavior must be understood. Methods to identify evolution of the internal strain (stress) state during thermal cycling are described. A slice of a package containing a single row of solder joints was thermally cycled from 0 C to 100 C with a period of about 1 h with concurrent acquisition of transmission Laue patterns using synchrotron radiation. These results indicated that most joints are single crystals, with some being multicrystals with no more than a few Sn grain orientations. Laue patterns were analyzed to estimate local strains in different crystal directions at different temperatures during a thermal cycle. While the strains perpendicular to various crystal planes all vary in a similar way, the magnitude of strain varies. The specimens were subsequently given several hundred additional thermal cycles and measured again to assess changes in the crystal orientations. These results show that modest changes in crystal orientations occur during thermal cycling.

  2. Soldering in electronics assembly

    CERN Document Server

    Judd, Mike

    2013-01-01

    Soldering in Electronics Assembly discusses several concerns in soldering of electronic assemblies. The book is comprised of nine chapters that tackle different areas in electronic assembly soldering. Chapter 1 discusses the soldering process itself, while Chapter 2 covers the electronic assemblies. Chapter 3 talks about solders and Chapter 4 deals with flux. The text also tackles the CS and SC soldering process. The cleaning of soldered assemblies, solder quality, and standards and specifications are also discussed. The book will be of great use to professionals who deal with electronic assem

  3. Interface between Sn-Sb-Cu solder and copper substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sebo, P., E-mail: Pavel.Sebo@savba.sk [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Racianska 75, 831 02 Bratislava 3 (Slovakia); Svec, P. [Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava 45 (Slovakia); Faculty of Materials Science and Technology, Slovak University of Technology, J. Bottu 25, 917 24 Trnava (Slovakia); Janickovic, D.; Illekova, E. [Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava 45 (Slovakia); Plevachuk, Yu. [Ivan Franko National University, Department of Metal Physics, 79005 Lviv (Ukraine)

    2011-07-15

    Highlights: {yields} New lead-free solder materials based on Sn-Sb-Cu were designed and prepared. {yields} Melting and solidification temperatures of the solders have been determined. {yields} Cu-substrate/solder interaction has been analyzed and quantified. {yields} Phases formed at the solder-substrate interface have been identified. {yields} Composition and soldering atmospheres were correlated with joint strength. - Abstract: Influence of antimony and copper in Sn-Sb-Cu solder on the melting and solidification temperatures and on the microstructure of the interface between the solder and copper substrate after wetting the substrate at 623 K for 1800 s were studied. Microstructure of the interface between the solder and copper substrates in Cu-solder-Cu joints prepared at the same temperature for 1800 s was observed and shear strength of the joints was measured. Influence of the atmosphere - air with the flux and deoxidising N{sub 2} + 10H{sub 2} gas - was taken into account. Thermal stability and microstructure were studied by differential scanning calorimetry (DSC), light microscopy, scanning electron microscopy (SEM) with energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD). Melting and solidification temperatures of the solders were determined. An interfacial transition zone was formed by diffusion reaction between solid copper and liquid solder. At the interface Cu{sub 3}Sn and Cu{sub 6}Sn{sub 5} phases arise. Cu{sub 3}Sn is adjacent to the Cu substrate and its thickness decreases with increasing the amount of copper in solder. Scallop Cu{sub 6}Sn{sub 5} phase is formed also inside the solder drop. The solid solution Sn(Sb) and SbSn phase compose the interior of the solder drop. Shear strength of the joints measured by push-off method decreases with increasing Sb concentration. Copper in the solder shows even bigger negative effect on the strength.

  4. Optimal parameters for laser tissue soldering

    Science.gov (United States)

    McNally-Heintzelman, Karen M.; Sorg, Brian S.; Chan, Eric K.; Welch, Ashley J.; Dawes, Judith M.; Owen, Earl R.

    1998-07-01

    Variations in laser irradiance, exposure time, solder composition, chromophore type and concentration have led to inconsistencies in published results of laser-solder repair of tissue. To determine optimal parameters for laser tissue soldering, an in vitro study was performed using an 808-nm diode laser in conjunction with an indocyanine green (ICG)- doped albumin protein solder to weld bovine aorta specimens. Liquid and solid protein solders prepared from 25% and 60% bovine serum albumin (BSA), respectively, were compared. The effects of laser irradiance and exposure time on tensile strength of the weld and temperature rise as well as the effect of hydration on bond stability were investigated. Optimum irradiance and exposure times were identified for each solder type. Increasing the BSA concentration from 25% to 60% greatly increased the tensile strength of the weld. A reduction in dye concentration from 2.5 mg/ml to 0.25 mg/ml was also found to result in an increase in tensile strength. The strongest welds were produced with an irradiance of 6.4 W/cm2 for 50 s using a solid protein solder composed of 60% BSA and 0.25 mg/ml ICG. Steady-state solder surface temperatures were observed to reach 85 plus or minus 5 degrees Celsius with a temperature gradient across the solid protein solder strips of between 15 and 20 degrees Celsius. Finally, tensile strength was observed to decrease significantly (20 to 25%) after the first hour of hydration in phosphate-buffered saline. No appreciable change was observed in the strength of the tissue bonds with further hydration.

  5. In situ NiTi/Nb(Ti) composite

    International Nuclear Information System (INIS)

    Jiang, Daqiang; Cui, Lishan; Jiang, Jiang; Zheng, Yanjun

    2013-01-01

    Graphical abstract: - Highlights: • In situ NiTi/Nb(Ti) composites were fabricated. • The transformation temperature was affected by the mixing Ti:Ni atomic ratios. • The NiTi component became micron-scale lamella after forging and rolling. • The composite exhibited high strength and high damping capacity. - Abstract: This paper reports on the creation of a series of in situ NiTi/Nb(Ti) composites with controllable transformation temperatures based on the pseudo-binary hypereutectic transformation of NiTi–Nb system. The composite constituent morphology was controlled by forging and rolling. It is found that the thickness of the NiTi lamella in the composite reached micron level after the hot-forging and cold-rolling. The NiTi/Nb(Ti) composite exhibited high damping capacity as well as high yield strength

  6. Influence of aging treatment on deformation behavior of 96.5Sn3.5Ag lead-free solder alloy during in situ tensile tests

    International Nuclear Information System (INIS)

    Ding, Ying; Wang, Chunqing; Tian, Yanhong; Li, Mingyu

    2007-01-01

    This study investigates the influence of aging treatment on deformation behavior of 96.5Sn3.5Ag eutectic solder alloys with lower strain rate ( -3 s -1 ) during tensile tests under the scanning electron microscope. Results showed that because of the existence of Ag 3 Sn intermetallic particles and the special microstructure of β-Sn phases in Sn3.5Ag solder, grain boundary sliding was not the dominant mechanism any longer for this Pb-free solder. While the interaction of dislocations with the relatively rigid Ag 3 Sn particles began to dominate. For the as-cast specimen, accompanied by partial intragranular cracks, intergranular fracture along the grain boundaries in Sn-Ag eutectic structure or the interphase boundaries between Sn-rich dendrites and Sn-Ag eutectic phases occurred primarily in early tensile stage. However, the boundary behavior was limited by the large Ag 3 Sn particles presented along the Sn-rich dendrites boundaries after aging. Plastic flow was observed in large area, and cracks propagated in a transgranular manner across the Sn-dendrites and Sn-Ag eutectic structure

  7. Evaluation on the characteristics of tin-silver-bismuth solder

    Science.gov (United States)

    Xia, Z.; Shi, Y.; Chen, Z.

    2002-02-01

    Tin-silver-bismuth solder is characterized by its lower melting point, good wetting behavior, and good mechanical property for which it is expected to be a new lead-free solder to replace tin-lead solder. In this article, Sn-3.33Ag-4.83Bi solder was investigated concerning its physical, spreading, and mechanical properties under specific conditions. Cooling curves and DSC results showed that it was close to eutectic composition (m.p. 210° 212 °C). Coefficiency of thermal expansion (CTE) of this solder, between that of PCBs and copper substrates, was beneficial to alleviate the thermal mismatch of the substrates. It was also a good electrical and thermal conductor. Using a rosin-based, mildly activated (RMA) flux, a spreading test indicated that SnAgBi solder paste had good solderability. Meanwhile, the solder had high tensile strength and fracture energy. Its fracture mechanism was a mixture of ductile and brittle fracture morphology. The metallographic and EDAX analyses indicated that it was composed of a tin-based solid solution and some intermetallic compound (IMC) that could strengthen the substrate. However, these large needle-like IMCs would cut the substrate and this resulted in the decreasing of the toughness of the solder.

  8. Correlation Between Pin Misalignment and Crack Length in THT Solder Joints

    Directory of Open Access Journals (Sweden)

    Molnar A.

    2017-06-01

    Full Text Available In this manuscript, correlations were searched for between pin misalignments relative to PCB bores and crack propagation after cyclic thermal shock tests in THT solder joints produced from lead-free solder alloys. In total, 7 compositions were examined including SAC solders with varying Ag, Cu and Ni contents. The crack propagation was initiated by cyclic thermal shock tests with 40°C / +125°C temperature profiles. Pin misalignments relative to the bores were characterized with three attributes obtained from one section of the examined solder joints. Cracks typically originated at the solder/pin or solder/bore interfaces and propagated within the solder. It was shown that pin misalignments did not have an effect on crack propagation, thus, the solder joints’ lifetime.

  9. Reliability Study of Solder Paste Alloy for the Improvement of Solder Joint at Surface Mount Fine-Pitch Components

    Directory of Open Access Journals (Sweden)

    Mohd Nizam Ab. Rahman

    2014-12-01

    Full Text Available The significant increase in metal costs has forced the electronics industry to provide new materials and methods to reduce costs, while maintaining customers’ high-quality expectations. This paper considers the problem of most electronic industries in reducing costly materials, by introducing a solder paste with alloy composition tin 98.3%, silver 0.3%, and copper 0.7%, used for the construction of the surface mount fine-pitch component on a Printing Wiring Board (PWB. The reliability of the solder joint between electronic components and PWB is evaluated through the dynamic characteristic test, thermal shock test, and Taguchi method after the printing process. After experimenting with the dynamic characteristic test and thermal shock test with 20 boards, the solder paste was still able to provide a high-quality solder joint. In particular, the Taguchi method is used to determine the optimal control parameters and noise factors of the Solder Printer (SP machine, that affects solder volume and solder height. The control parameters include table separation distance, squeegee speed, squeegee pressure, and table speed of the SP machine. The result shows that the most significant parameter for the solder volume is squeegee pressure (2.0 mm, and the solder height is the table speed of the SP machine (2.5 mm/s.

  10. (FSP) of Al–TiC in situ composite

    Indian Academy of Sciences (India)

    An Al-5 wt% TiC composite was processed in situ using K2TiF6 and graphite in Al melt and subjected to FSP. Processing parameters for FSP were optimized to get a defect free stir zone and homogenize the particle distribution. It was found that a rotation speed > 800 rpm is needed. A rotation speed of 1000 rpm and a ...

  11. Recent Advances in Nb-silicide in-situ composites

    International Nuclear Information System (INIS)

    Bewlay, B.P.; Jackson, M.R.; Subramanian, P.R.; Briant, C.L.

    2001-01-01

    In-situ composites based on Nb silicides have great potential for future high-temperature applications. These Nb-silicide composites combine a ductile Nb-based matrix with high-strength silicides. With the appropriate combination of alloying elements, such as Ti, Hf, Cr, AI, it is possible to achieve a promising balance of fracture toughness, high-temperature creep performance, and oxidation resistance. This paper will describe the effect of volume fraction of silicide on microstructure, high-temperature creep performance, and oxidation resistance. The ratio of Nb:(W+Ti) is critical in determining both creep rate and oxidation performance. If this ratio goes below ∼1.5, the creep rate increases substantially. In more complex silicide-based systems, other intermetallics, such as laves phases and a boron-rich T-2 phase, are added for oxidation resistance. To understand the role of each phase on the creep resistance and oxidation performance of these composites, we determined the creep and oxidation behavior of the individual phases and composites at temperatures up to 1200 o C. These data allow quantification of the load-bearing capability of the individual phases in the Nb-silicide based in-situ composites. (author)

  12. The effect of graphene on the intermetallic and joint strength of Sn-3.5Ag lead-free solder

    Science.gov (United States)

    Mayappan, R.; Salleh, A.; Andas, J.

    2017-09-01

    Solder has been widely used in electronic industry as interconnection for electronic packaging. European Union and Japan have restricted the use of Sn-Pb solder as it contains lead which can harmful to human health and environment. Due to this, many researches have been done in order to find a suitable replacement for the lead solder. Although many lead-free solders are available, the Sn-3.5Ag solder with the addition of graphene seem to be a suitable candidate. In this study, a 0.07 wt% graphene nanosheet was added into the Sn-3.5Ag solder and this composite solder was prepared under powder metallurgy method. The solder was reacted with copper substrate at 250 °C for one minute. For joint strength analysis, two copper strips were soldered together. The solder joint was aged at temperature 100 °C for 500 hours. Scanning Electron Microscope (SEM) was used to observe the interfacial reaction and Instron machine was used to determine the joint strength. Cu6Sn5 intermetallic layer was formed at the interface between the Cu substrate and the solders. Composite solder showed the retardation of the intermetallic growth compared to the plain solder. The thickness value of the intermetallic was used to calculate the growth rate the IMC. The graphene nanosheets added solder has lower growth rate which is 3.86 × 10-15 cm2/s compared to the plain solder 7.15 × 10-15 cm2/s. Shear strength analysis show that the composite solder has higher joint compared to the plain solder.

  13. Characterization of alginate-brushite in-situ hydrogel composites

    Energy Technology Data Exchange (ETDEWEB)

    Dabiri, Seyed Mohammad Hossein [Department of Informatics, Bioengineering, Robotics, and System Engineering, University of Genoa, Genoa (Italy); Lagazzo, Alberto; Barberis, Fabrizio [Department of Civil, Chemical and Environmental Engineering, University of Genoa, Genoa (Italy); Farokhi, Mehdi [National Cell Bank of Iran, Pasteur Institute of Iran, Tehran (Iran, Islamic Republic of); Finochio, Elisabetta [Department of Civil, Chemical and Environmental Engineering, University of Genoa, Genoa (Italy); Pastorino, Laura [Department of Informatics, Bioengineering, Robotics, and System Engineering, University of Genoa, Genoa (Italy)

    2016-10-01

    In the present study alginate-brushite composite hydrogels were in-situ synthetized and characterized with respect to preparation parameters. Specifically, the influence of initial pH value and initial concentration of phosphate precursor on the in-situ fabrication of the composite hydrogel were taken into account. The composite hydrogels were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric (TGA, DTG) and differential thermal analysis (DTA). Finally, the cell viability tests were carried out (MTT) over the incubation time period of 3, 7, and 14 days. The results revealed that the formation and the crystalline stability of brushite were highly dependent on the initial pH value. It was shown that as the pH reached to the value of 6, characteristics peaks of brushite appeared in the FTIR spectra. Besides, the XRD and thermal analysis results were in a good accordance with those of FTIR. In addition, the SEM images demonstrated that the plate like brushite was formed inside the alginate matrix. Also, a considerable impact of pH variation on the biocompatibility of samples was noticed so that the majority of samples especially those prepared in the acidic conditions were toxic. - Highlights: • Alginate-brushite hydrogel composites were obtained through an in-situ process • The brushite crystals started forming at pH value of 6 • The increase in the initial concentration of phosphate precursor resulted in more crystalline structure • Samples prepared at pH value of 8 had the most stable crystalline structure • Brushite crystals promoted the biocompatibility of alginate.

  14. Polyimide resin composites via in situ polymerization of monomeric reactants

    Science.gov (United States)

    Cavano, P. J.

    1974-01-01

    Thermo-oxidatively stable polyimide/graphite-fiber composites were prepared using a unique in situ polymerization of monomeric reactants directly on reinforcing fibers. This was accomplished by using an aromatic diamine and two ester-acids in a methyl alcohol solvent, rather than a previously synthesized prepolymer varnish, as with other A-type polyimides. A die molding procedure was developed and a composite property characterization conducted with high modulus graphite fiber tow. Flexure, tensile, compressive, and shear tests were conducted at temperatures from 72 to 650 F on laminates before and after exposures at the given temperatures in an air environment for times up to 1000 hours. The composite material was determined to be oxidatively, thermally, and hydrolytically stable.

  15. In-situ poling and structurization of piezoelectric particulate composites.

    Science.gov (United States)

    Khanbareh, H; van der Zwaag, S; Groen, W A

    2017-11-01

    Composites of lead zirconate titanate particles in an epoxy matrix are prepared in the form of 0-3 and quasi 1-3 with different ceramic volume contents from 10% to 50%. Two different processing routes are tested. Firstly a conventional dielectrophoretic structuring is used to induce a chain-like particle configuration, followed by curing the matrix and poling at a high temperature and under a high voltage. Secondly a simultaneous combination of dielectrophoresis and poling is applied at room temperature while the polymer is in the liquid state followed by subsequent curing. This new processing route is practiced in an uncured thermoset system while the polymer matrix still possess a relatively high electrical conductivity. Composites with different degrees of alignment are produced by altering the magnitude of the applied electric field. A significant improvement in piezoelectric properties of quasi 1-3 composites can be achieved by a combination of dielectrophoretic alignment of the ceramic particles and poling process. It has been observed that the degree of structuring as well as the functional properties of the in-situ structured and poled composites enhance significantly compared to those of the conventionally manufactured structured composites. Improving the alignment quality enhances the piezoelectric properties of the particulate composites.

  16. Soldering formalism in noncommutative field theory: a brief note

    International Nuclear Information System (INIS)

    Ghosh, Subir

    2004-01-01

    In this Letter, I develop the soldering formalism in a new domain--the noncommutative planar field theories. The soldering mechanism fuses two distinct theories showing opposite or complimentary properties of some symmetry, taking into account the interference effects. The above mentioned symmetry is hidden in the composite (or soldered) theory. In the present work it is shown that a pair of noncommutative Maxwell-Chern-Simons theories, having opposite signs in their respective topological terms, can be consistently soldered to yield the Proca model (Maxwell theory with a mass term) with corrections that are at least quadratic in the noncommutativity parameter. We further argue that this model can be thought of as the noncommutative generalization of the Proca theory of ordinary spacetime. It is well known that abelian noncommutative gauge theory bears a close structural similarity with non-abelian gauge theory. This fact is manifested in a non-trivial way if the present Letter is compared with existing literature, where soldering of non-abelian models are discussed. Thus the present work further establishes the robustness of the soldering programme. The subtle role played by gauge invariance (or the lack of it), in the above soldering process, is revealed in an interesting way

  17. Utilization of Pb-free solders in MEMS packaging

    Science.gov (United States)

    Selvaduray, Guna S.

    2003-01-01

    Soldering of components within a package plays an important role in providing electrical interconnection, mechanical integrity and thermal dissipation. MEMS packages present challenges that are more complex than microelectronic packages because they are far more sensitive to shock and vibration and also require precision alignment. Soldering is used at two major levels within a MEMS package: at the die attach level and at the component attach level. Emerging environmental regulations worldwide, notably in Europe and Japan, have targeted the elimination of Pb usage in electronic assemblies, due to the inherent toxicity of Pb. This has provided the driving force for development and deployment of Pb-free solder alloys. A relatively large number of Pb-free solder alloys have been proposed by various researchers and companies. Some of these alloys have also been patented. After several years of research, the solder alloy system that has emerged is based on Sn as a major component. The electronics industry has identified different compositions for different specific uses, such as wave soldering, surface mount reflow, etc. The factors that affect choice of an appropriate Pb-free solder can be divided into two major categories, those related to manufacturing, and those related to long term reliability and performance.

  18. Interfacial reaction of Sn-based solder joint in the package system

    Science.gov (United States)

    Gu, Huandi

    In this thesis, I report a study on the effect of the solder size on intermetallic layer formation by comparing the morphology change and growth rate of two different size solder joint aged at a same temperature for different aging time. The layer thickness and microstructure were analyzed using scanning electron microscopy (SEM). Photoshop was used to measure the thickness of intermetallic compound. Two different size of solder joints with composition of Sn-Ag-Cu (305) were used.

  19. Effect of solder bump size on interfacial reactions during soldering between Pb-free solder and Cu and Ni/ Pd/ Au surface finishes

    International Nuclear Information System (INIS)

    NorAkmal, F.; Ourdjini, A.; Azmah Hanim, M.A.; Siti Aisha, I.; Chin, Y.T.

    2007-01-01

    Flip chip technology provides the ultimate in high I/ O-density and count with superior electrical performance for interconnecting electronic components. Therefore, the study of the intermetallic compounds was conducted to investigate the effect of solder bumps sizes on several surface finishes which are copper and Electroless Nickel/ Electroless Palladium/ Immersion Gold (ENEPIG) which is widely used in electronics packaging as surface finish for flip-chip application nowadays. In this research, field emission scanning electron microscopy (FESEM) analysis was conducted to analyze the morphology and composition of intermetallic compounds (IMCs) formed at the interface between the solder and UBM. The IMCs between the SAC lead-free solder with Cu surface finish after reflow were mainly (Cu, Ni) 6 Sn 5 and Cu 6 Sn 5 . While the main IMCs formed between lead-free solder on ENEPIG surface finish are (Ni, Cu) 3 Sn 4 and Ni 3 Sn 4 . The results from FESEM with energy dispersive x-ray (EDX) have revealed that isothermal aging at 150 degree Celsius has caused the thickening and coarsening of IMCs as well as changing them into more spherical shape. The thickness of the intermetallic compounds in both finishes investigated was found to be higher in solders with smaller bump size. From the experimental results, it also appears that the growth rate of IMCs is higher when soldering on copper compared to ENEPIG finish. Besides that, the results also showed that the thickness of intermetallic compounds was found to be proportional to isothermal aging duration. (author)

  20. Solder wetting behavior enhancement via laser-textured surface microcosmic topography

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Haiyan [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Shaanxi Key Laboratory of Friction Welding Technologies, Xi’an 710072 (China); Peng, Jianke [Shaanxi Key Laboratory of Friction Welding Technologies, Xi’an 710072 (China); Fu, Li, E-mail: fuli@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072 (China); Shaanxi Key Laboratory of Friction Welding Technologies, Xi’an 710072 (China); Wang, Xincheng [Shaanxi Key Laboratory of Friction Welding Technologies, Xi’an 710072 (China); Xie, Yan [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

    2016-04-15

    Graphical abstract: - Highlights: • The wetting angle of lead free solder on Cu was reduced by surface microstructure. • The wetting form of Sn-Ag-Cu solder on Cu was “non-composite surface”. • The experimental results had a sound fit with the theoretical calculation. - Abstract: In order to reduce or even replace the use of Sn-Pb solder in electronics industry, the laser-textured surface microstructures were used to enhance the wetting behavior of lead free solder during soldering. According to wetting theory and Sn-Ag-Cu lead free solder performance, we calculated and designed four microcosmic structures with the similar shape and different sizes to control the wetting behavior of lead free solder. The micro-structured surfaces with different dimensions were processed on copper plates by fiber femtosecond laser, and the effect of microstructures on wetting behavior was verified experimentally. The results showed that the wetting angle of Sn-Ag-Cu solder on the copper plate with microstructures decreased effectively compared with that on the smooth copper plate. The wetting angles had a sound fit with the theoretical values calculated by wetting model. The novel method provided a feasible route for adjusting the wetting behavior of solders and optimizing solders system.

  1. In situ polymerization of monomers for polyphenylquinoxaline-graphite fiber composites

    Science.gov (United States)

    Serafini, T. T.; Delvigs, P.; Vannucci, R. D.

    1974-01-01

    In situ polymerization of monomers was used to prepare graphite-fiber-reinforced polyphenylquinoxaline composites. Six different monomer combinations were investigated. Composite mechanical property retention characteristics were determined at 316 C (600 F) over an extended time period.

  2. Soldering of Nanotubes onto Microelectrodes

    DEFF Research Database (Denmark)

    Madsen, Dorte Nørgaard; Mølhave, Kristian; Mateiu, Ramona Valentina

    2003-01-01

    Suspended bridges of individual multiwalled carbon nanotubes were fabricated inside a scanning electron microscope by soldering the nanotube onto microelectrodes with highly conducting gold-carbon material. By the decomposition of organometallic vapor with the electron beam, metal-containing sold...... bonds were consistently found to be mechanically stronger than the carbon nanotubes.......Suspended bridges of individual multiwalled carbon nanotubes were fabricated inside a scanning electron microscope by soldering the nanotube onto microelectrodes with highly conducting gold-carbon material. By the decomposition of organometallic vapor with the electron beam, metal-containing solder...... bonds were formed at the intersection of the nanotube and the electrodes. Current-voltage curves indicated metallic conduction of the nanotubes, with resistances in the range of 9-29 kOmega. Bridges made entirely of the soldering material exhibited resistances on the order of 100 Omega, and the solder...

  3. In-situ change and repairing method of armour tile made of carbon fiber composite material in divertor

    International Nuclear Information System (INIS)

    Ishiyama, Shintaro.

    1994-01-01

    A joint portion of a damaged armour tile of a carbon fiber composite material and a divertor substrate is locally heated spontaneously to re-melt the soldering. Then, the damaged tile is removed and the portion where the tile is removed is heated again to melt the soldering, then a tile for exchange is joined. Alternatively, a thermosetting type adhesive is coated on the surface of the damaged armour tile made of carbon fiber composite material on the divertor, and a tile for repairing is adhered thereon then the joint surface is locally heated to cure the adhesive. For local heating, for example, high frequency heating or dielectric heating is used. It is preferably conducted by remote handling by using robot arms under vacuum in an vacuum vessel of the thermonuclear device. The operations of the heating and pressurization for the joint surface are preferably repeated for several times. (N.H.)

  4. Polyethylene-waste tire dust composites via in situ polymerization

    International Nuclear Information System (INIS)

    Reyes A, Y. K.; Narro C, R. I.; Ramos A, M. E.; Neira V, M. G.; Diaz E, J.; Enriquez M, F.; Valencia L, L. A.; Saade C, H.; Diaz de L, R.

    2014-01-01

    Polyethylene/waste tire dust (WTD) composites were obtained by an in situ polymerization technique. The surface of the WTD was modified with deposition of polyethylene by using plasma polymerization. Ethylene polymerization was carried out using bis(cyclopentadienyl) titanium dichloride (Cp 2 TiCl 2 ) as homogeneous metallocenes catalyst, while diethylaluminum chloride (DEAC), ethyl aluminum sesquichloride (EASC) and methyl alumino xane (Mao) were used as co-catalysts at two different [Al]/[Ti] molar ratio. The main characteristics of the obtained polyethylenes were determined by size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry and wide-angle X-ray diffraction. The results showed that by using EASC and Mao the highest catalytic activities were presented at a [Al]/[Ti] molar ratio of 9.17 and 18.33 respectively. Even though it was possible to obtain polyethylene using WTD (modified or unmodified) the catalytic activity was lower than in the case in which no WTD was added in ethylene polymerization. Scanning transmission electronic microscopy images evidenced that the original morphology of the polyethylenes was not modified by the presence of WTD. (Author)

  5. Polyethylene-waste tire dust composites via in situ polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Reyes A, Y. K.; Narro C, R. I.; Ramos A, M. E. [Universidad Autonoma de Coahuila, Facultad de Ciencias Quimicas, Blvd. Venustiano Carranza s/n, 25280 Saltillo, Coahuila (Mexico); Neira V, M. G.; Diaz E, J.; Enriquez M, F.; Valencia L, L. A.; Saade C, H.; Diaz de L, R., E-mail: ramon.diazdeleon@ciqa.edu.mx [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna Hermosillo No. 40, Col. San Jose de los Cerritos, 25293 Saltillo, Coahuila (Mexico)

    2014-10-01

    Polyethylene/waste tire dust (WTD) composites were obtained by an in situ polymerization technique. The surface of the WTD was modified with deposition of polyethylene by using plasma polymerization. Ethylene polymerization was carried out using bis(cyclopentadienyl) titanium dichloride (Cp{sub 2}TiCl{sub 2}) as homogeneous metallocenes catalyst, while diethylaluminum chloride (DEAC), ethyl aluminum sesquichloride (EASC) and methyl alumino xane (Mao) were used as co-catalysts at two different [Al]/[Ti] molar ratio. The main characteristics of the obtained polyethylenes were determined by size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry and wide-angle X-ray diffraction. The results showed that by using EASC and Mao the highest catalytic activities were presented at a [Al]/[Ti] molar ratio of 9.17 and 18.33 respectively. Even though it was possible to obtain polyethylene using WTD (modified or unmodified) the catalytic activity was lower than in the case in which no WTD was added in ethylene polymerization. Scanning transmission electronic microscopy images evidenced that the original morphology of the polyethylenes was not modified by the presence of WTD. (Author)

  6. Effect of Multiple Reflow Cycles and Al2O3 Nanoparticles Reinforcement on Performance of SAC305 Lead-Free Solder Alloy

    Science.gov (United States)

    Tikale, Sanjay; Prabhu, K. Narayan

    2018-05-01

    The effect of Al2O3 nanoparticles reinforcement on melting behavior, microstructure evolution at the interface and joint shear strength of 96.5Sn3Ag0.5Cu (SAC305) lead-free solder alloy subjected to multiple reflow cycles was investigated. The reinforced SAC305 solder alloy compositions were prepared by adding Al2O3 nanoparticles in different weight fractions (0.05, 0.1, 0.3 and 0.5 wt.%) through mechanical dispersion. Cu/solder/Cu micro-lap-shear solder joint specimens were used to assess the shear strength of the solder joint. Differential scanning calorimetry was used to investigate the melting behavior of SAC305 solder nanocomposites. The solder joint interfacial microstructure was studied using scanning electron microscopy. The results showed that the increase in melting temperature (T L) and melting temperature range of the SAC305 solder alloy by addition of Al2O3 nanoparticles were not significant. In comparison with unreinforced SAC305 solder alloy, the reinforcement of 0.05-0.5 wt.% of Al2O3 nanoparticles improved the solder wettability. The addition of nanoparticles in minor quantity effectively suppressed the Cu6Sn5 IMC growth, improved the solder joint shear strength and ductility under multiple reflow cycles. However, the improvement in solder properties was less pronounced on increasing the nanoparticle content above 0.1 wt.% of the solder alloy.

  7. On the problem of soldering refractory metals with silver-containing solders

    International Nuclear Information System (INIS)

    Anikeev, E.F.; Andryushchenko, V.I.; Chepelenko, V.N.; Batov, V.M.

    1981-01-01

    The processes of wetting, spreading and interphase interactions of copper-silver liquid alloys alloyed with Ni and Si, with niobium, tantalum, molybdenum, tungsten, 12Kh18N10T steel and nickel are studied. It has been determined that Ni or Si additions into the copper-silver solder improve the wetting and adhesion. When soldering with the alloy containing Ni additions, the strength of a soldered Joint grows with the increase of soldering duration while soldering with the alloy containing Si additions, the strength decreases. That is why Ni-containing solders are preferable for soldering thick-walled structures, and Si-containing solders - for thin-walled structures [ru

  8. In Situ Manufacturing of Plastics and Composites to Support H&R Exploration, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering and BAE Systems propose to develop processes to manufacture plastics and composites for radiation shielding based on In Situ Resources Utilization...

  9. Multiscale Stochastic Fracture Mechanics of Composites Informed by In-situ XCT Tests

    Science.gov (United States)

    2016-02-02

    interfacial fracture ) in CFRP was recently found in the fuselages of Dreamliner 787, and two types of cracks were found in the rib feet brackets...AFRL-AFOSR-UK-TR-2016-0003 Multiscale Stochastic Fracture Mechanics of Composites Informed by In-situ XCT Tests Zhenjun Yang UNIVERSITY OF MANCHESTER...Multiscale Stochastic Fracture Mechanics of Composites Informed by In-situ XCT Tests 5a. CONTRACT NUMBER EOARD 12-2100 5b. GRANT NUMBER F8655-12-1

  10. Preparation of Ti-aluminide reinforced in situ aluminium matrix composites by reactive hot pressing

    International Nuclear Information System (INIS)

    Roy, D.; Ghosh, S.; Basumallick, A.; Basu, B.

    2007-01-01

    Aluminium based metal matrix composites reinforced with in situ Ti-aluminide and alumina particles were prepared by reactive hot pressing a powder mix of aluminium and nanosized TiO 2 powders. The reinforcements were formed in situ by exothermal reaction between the TiO 2 nano crystalline powder and aluminium. The thermal characteristics of the in situ reaction were studied with the aid of Differential scanning calorimetry (DSC). X-ray diffraction (XRD), Energy dispersive spectroscopy (EDS) and Scanning electron microscopy (SEM) techniques were employed to study the microstructural architecture of the composites as a function of hot pressing temperature and volume percent reinforcement. Microhardness measurements on the as prepared in situ aluminium matrix composites exhibit significant increase in hardness with increase in hot pressing temperature and volume fraction of reinforcement

  11. Solder joint technology materials, properties, and reliability

    CERN Document Server

    Tu, King-Ning

    2007-01-01

    Solder joints are ubiquitous in electronic consumer products. The European Union has a directive to ban the use of Pb-based solders in these products on July 1st, 2006. There is an urgent need for an increase in the research and development of Pb-free solders in electronic manufacturing. For example, spontaneous Sn whisker growth and electromigration induced failure in solder joints are serious issues. These reliability issues are quite complicated due to the combined effect of electrical, mechanical, chemical, and thermal forces on solder joints. To improve solder joint reliability, the science of solder joint behavior under various driving forces must be understood. In this book, the advanced materials reliability issues related to copper-tin reaction and electromigration in solder joints are emphasized and methods to prevent these reliability problems are discussed.

  12. Polyindole/ carboxylated-multiwall carbon nanotube composites produced by in-situ and interfacial polymerization

    International Nuclear Information System (INIS)

    Joshi, Leela; Singh, Arun Kumar; Prakash, Rajiv

    2012-01-01

    Composites of polyindole (PIn), a conducting polymer, with carboxylated-multiwalled carbon nanotubes (c-MWCNT/PIn) were synthesized; the synthesis was done using (i) two miscible solvents (in-situ method) and (ii) two immiscible solvents (interfacial method). A tubular composite, with a uniform coating of the polymer over c-MWCNTs, was observed in the case of interfacial synthesis. However, the in-situ synthesis of c-MWCNT/PIn composites exhibited a densely packed spherical morphology, with c-MWCNT incorporated within the polymer spheres. The spherical morphology was probably obtained due to fast polymerization kinetics and the formation of micelles in case of in-situ polymerization, whereas tubular morphology was obtained in case of interfacial polymerization due to the sufficient time provided for the growth of polymer chains over the c-MWCNT surfaces. Nanoscale electrical properties of composites, in a metal/(c-MWCNT/PIn) configuration, were studied using current sensing atomic force microscopy. Interfacial c-MWCNT/PIn composite, on Al metal substrate, exhibited a typical rectifying diode behavior. This composite had manifested enormous potential for electronic applications and fabrication of nanoscale organic devices. Highlights: ► Polyindole/c-MWNT nanocomposites produced by in-situ and interfacial polymerization. ► Densely packed spherical morphology was observed in in-situ polymerization route. ► Tubular core-shell morphology was observed in interfacial polymerization route. ► Interfacial nanocomposite manifested a nano-schottky junction with Al metal.

  13. Fabrication of Nanocarbon Composites Using In Situ Chemical Vapor Deposition and Their Applications.

    Science.gov (United States)

    He, Chunnian; Zhao, Naiqin; Shi, Chunsheng; Liu, Enzuo; Li, Jiajun

    2015-09-23

    Nanocarbon (carbon nanotubes (CNTs) and graphene (GN)) composites attract considerable research interest due to their fascinating applications in many fields. Here, recent developments in the field of in situ chemical vapor deposition (CVD) for the design and controlled preparation of advanced nanocarbon composites are highlighted, specifically, CNT-reinforced bulk structural composites, as well as CNT, GN, and CNT/GN functional composites, together with their practical and potential applications. In situ CVD is a very attractive approach for the fabrication of composites because of its engaging features, such as its simplicity, low-cost, versatility, and tunability. The morphologies, structures, dispersion, and interface of the resulting nanocarbon composites can be easily modulated by varying the experimental parameters (such as temperature, catalysts, carbon sources, templates or template catalysts, etc.), which enables a great potential for the in situ synthesis of high-quality nanocarbons with tailored size and dimension for constructing high-performance composites, which has not yet been achieved by conventional methods. In addition, new trends of the in situ CVD toward nanocarbon composites are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Nanoscale Soldering of Positioned Carbon Nanotubes using Highly Conductive Electron Beam Induced Gold Deposition

    DEFF Research Database (Denmark)

    Madsen, Dorte Nørgaard; Mølhave, Kristian; Mateiu, Ramona Valentina

    2003-01-01

    We have developed an in-situ method for controlled positioning of carbon nanotubes followed by highly conductive contacting of the nanotubes, using electron beam assisted deposition of gold. The positioning and soldering process takes place inside an Environmental Scanning Electron Microscope (E...... in a carbon matrix. Nanoscale soldering of multi-walled carbon nanotubes (MWNT) onto microelectrodes was achieved by deposition of a conducting gold line across a contact point between nanotube and electrode. The solderings were found to be mechanically stronger than the carbon nanotubes. We have positioned...... MWNTs to bridge the gap between two electrodes, and formed soldering bonds between the tube and each of the electrodes. All nanotube bridges showed ohmic resistances in the range 10-30 kΩ. We observed no increase in resistance after exposing the MWNT bridge to air for days....

  15. Production of mullite-zirconia ceramics composites by 'In situ' reaction

    International Nuclear Information System (INIS)

    Melo, F.C.L. de; Cairo, C.A.A.; Piorino Neto, F.; Devezas, T.C.

    1987-01-01

    Mullita-zirconia ceramic composites were produced by 'In situ' reaction of alumina and brazilian zircon. The ideal curve of thermal treatment (reaction + sinterization) was determined for the obtention of composites of maximum mechanical resistence. The retained fraction of tetragonal fase was evaluated by X-ray difraction and correlated with the values of mechanical resistence obtained by different treatment curves. The performance of the developed composites under corrosion and thermal shock was evaluated by glass casting. (Author) [pt

  16. Contamination profile of Printed Circuit Board Assemblies in relation to soldering types and conformal coating

    DEFF Research Database (Denmark)

    Conseil, Helene; Jellesen, Morten Stendahl; Ambat, Rajan

    2014-01-01

    Typical printed circuit board assemblies (PCBAs) processed by reflow, wave, or selective wave soldering were analysed for typical levels of process related residues, resulting from a specific or combination of soldering process. Typical solder flux residue distribution pattern, composition......, and concentration are profiled and reported. Presence of localized flux residues were visualized using a commercial Residue RAT gel test and chemical structure was identified by FT-IR, while the concentration was measured using ion chromatography, and the electrical properties of the extracts were determined...

  17. Fabrication of in-situ grown graphene reinforced Cu matrix composites

    Science.gov (United States)

    Chen, Yakun; Zhang, Xiang; Liu, Enzuo; He, Chunnian; Shi, Chunsheng; Li, Jiajun; Nash, Philip; Zhao, Naiqin

    2016-01-01

    Graphene/Cu composites were fabricated through a graphene in-situ grown approach, which involved ball-milling of Cu powders with PMMA as solid carbon source, in-situ growth of graphene on flaky Cu powders and vacuum hot-press sintering. SEM and TEM characterization results indicated that graphene in-situ grown on Cu powders guaranteed a homogeneous dispersion and a good combination between graphene and Cu matrix, as well as the intact structure of graphene, which was beneficial to its strengthening effect. The yield strength of 244 MPa and tensile strength of 274 MPa were achieved in the composite with 0.95 wt.% graphene, which were separately 177% and 27.4% enhancement over pure Cu. Strengthening effect of in-situ grown graphene in the matrix was contributed to load transfer and dislocation strengthening. PMID:26763313

  18. Self-healing composites: in-situ repair solutions

    NARCIS (Netherlands)

    Coope, T.S.; Luterbacher, R.; Turkenburg, D.H.; Fischer, H.R.; Bond, I.P.

    2015-01-01

    Realising self-healing composites in a commercial environment remains a challenge for the transport sector. Herein, this research considers the design envelope and the implications of embedding self-healing agents into commercially relevant fibre reinforced polymer (FRP) composite applications. A

  19. Microstructural evolution and strengthening behavior in in-situ magnesium matrix composites fabricated by solidification processing

    Energy Technology Data Exchange (ETDEWEB)

    Chelliah, Nagaraj M., E-mail: cmnraj.7@gmail.com [Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab (India); Singh, Harpreet, E-mail: harpreetsingh@iitrpr.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab (India); Surappa, M.K., E-mail: mirle@materials.iisc.ac.in [Department of Materials Engineering, Indian Institute of Science, Bengaluru 560012, Karnataka (India)

    2017-06-15

    In-situ magnesium matrix composites with three different matrix materials (including Mg, AZ91 and AE44 Mg-alloys) were fabricated by injecting cross-linked polymer directly into the molten Mg/Mg-alloys, and having it convert to the 2.5 vol% SiCNO ceramic phase using liquid stir-casting method. In-situ chemical reaction took place within the molten slurry tending to produce 42 and 18 vol% Mg{sub 2}Si crystals in Mg and AE44 matrix composites, respectively but not in AZ91 matrix composite. Microstructural evolution of Mg{sub 2}Si crystals was discussed on the basis of availability of heterogeneous nucleation sites and amount of Al-atoms in the molten slurry. The observed micro-hardness and yield strengths are enhanced by factor of four to three as compared to their unreinforced counterparts, and Taylor strengthening was found to be the predominant strengthening mechanism in magnesium and AE44 matrix composites. Summation model predicted the yield strengths of the fabricated composites more preciously when compared to Zhang and Chen, and modified Clyne models. - Highlights: • In-situ magnesium composites were fabricated using liquid stir-casting method. • In-situ pyrolysis of cross-linked polymer has been utilized to obtain ceramic phases. • Mg{sub 2}Si crystals were formed in magnesium and AE44 matrix composites but not in AZ91 matrix composites. • The variation in size and morphology of Mg{sub 2}Si crystals with matrix materials are discussed. • Strengthening mechanisms in in-situ composites are analyzed and discussed.

  20. Handbook of machine soldering SMT and TH

    CERN Document Server

    Woodgate, Ralph W

    1996-01-01

    A shop-floor guide to the machine soldering of electronics Sound electrical connections are the operational backbone of every piece of electronic equipment-and the key to success in electronics manufacturing. The Handbook of Machine Soldering is dedicated to excellence in the machine soldering of electrical connections. Self-contained, comprehensive, and down-to-earth, it cuts through jargon, peels away outdated notions, and presents all the information needed to select, install, and operate machine soldering equipment. This fully updated and revised volume covers all of the new technologies and processes that have emerged in recent years, most notably the use of surface mount technology (SMT). Supplemented with 200 illustrations, this thoroughly accessible text Describes reflow and wave soldering in detail, including reflow soldering of SMT boards and the use of nitrogen blankets * Explains the setup, operation, and maintenance of a variety of soldering machines * Discusses theory, selection, and control met...

  1. Probing the phase composition of silicon films in situ by etch product detection

    International Nuclear Information System (INIS)

    Dingemans, G.; Donker, M. N. van den; Gordijn, A.; Kessels, W. M. M.; Sanden, M. C. M. van de

    2007-01-01

    Exploiting the higher etch probability for amorphous silicon relative to crystalline silicon, the transiently evolving phase composition of silicon films in the microcrystalline growth regime was probed in situ by monitoring the etch product (SiH 4 ) gas density during a short H 2 plasma treatment step. Etch product detection took place by the easy-to-implement techniques of optical emission spectroscopy and infrared absorption spectroscopy. The phase composition of the films was probed as a function of the SiH 4 concentration during deposition and as a function of the film thickness. The in situ results were corroborated by Raman spectroscopy and solar cell analysis

  2. In situ polymerization of monomers for polyphenylquinoxaline/graphite fiber composites

    Science.gov (United States)

    Serafini, T. T.; Delvigs, P.; Vannucci, R. D.

    1974-01-01

    Methods currently used to prepare fiber reinforced, high temperature resistant polyphenylquinoxaline (PPQ) composites employ extremely viscous, low solids content solutions of high molecular weight PPQ polymers. An improved approach, described in this report, consists of impregnating the fiber with a solution of the appropriate monomers instead of a solution of previously synthesized high molecular weight polymer. Polymerization of the monomers occurs in situ on the fiber during the solvent removal and curing stages. The in situ polymerization approach greatly simplifies the fabrication of PPQ graphite fiber composites. The use of low viscosity monomeric type solutions facilitates fiber wetting, permits a high solids content, and eliminates the need for prior polymer synthesis.

  3. Tribological behavior of in situ Ag nanoparticles/polyelectrolyte composite molecular deposition films

    International Nuclear Information System (INIS)

    Guo Yanbao; Wang Deguo; Liu Shuhai

    2010-01-01

    Multilayer polyelectrolyte films containing silver ions were obtained by molecular deposition method on a glass plate or a quartz substrate. The in situ Ag nanoparticles were synthesized in the multilayer polyelectrolyte films which were put into fresh NaBH 4 aqueous solution. The structure and surface morphology of composite molecular deposition films were observed by UV-vis spectrophotometer, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Tribological characteristic was investigated by AFM and micro-tribometer. It was found that the in situ Ag nanoparticles/polyelectrolyte composite molecular deposition films have lower coefficient of friction and higher anti-wear life than pure polyelectrolyte molecular deposition films.

  4. Investigation into mechanical properties of joints of heterogeneous materials brazed with high-temperature solders

    International Nuclear Information System (INIS)

    Lomenko, V.I.; Merkushev, V.P.; Borodina, L.M.; Sycheva, T.S.; Tokhtina, O.A.; Frolov, N.N.

    1988-01-01

    Mechanical properties of copper joints with copper, 12Kh18M10T steel and KhD50 composite obtained by vacuum brazing by copper-titanium solder as compared with properties of joints brazed by PSr 72 and PMFOTsr 6-4-0.03 solders in hydrogen are studied. Dependences of joints strength on temperature of contact - reactive vacuum brazing are obtained. Possible applications of joints of dissimilar materials in electrovacuum devices subjected to the effect of dynamic loadings are established

  5. Compressive deformation of in situ formed bulk metallic glass composites

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, B. [Lujan Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lee, S.Y. [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Ustuendag, E. [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States)]. E-mail: ustundag@iastate.edu; Kim, C.P. [Liquidmetal Technologies, Lake Forest, CA 92630 (United States); Brown, D.W. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bourke, M.A.M. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2006-02-15

    A bulk metallic glass matrix composite with dendc second phase precipitates was investigated using neutron diffraction and self-consistent modeling (SCM) to ascertain its deformation mechanisms. The compressive behavior of both the composite and the second phase (in its monolithic form) were investigated. The diffraction data were compared to the predictions of a new SCM resulting in good agreement. For the first time, this model considered both amorphous and crystalline phases and allowed the calculation of single crystal elastic constants from polycrystalline diffraction data. It was shown that the ductile second phase yielded first upon loading, and this was followed by multiple shear band formation in the matrix, a process which enhanced the ductility of the composite.

  6. Compressive deformation of in situ formed bulk metallic glass composites

    International Nuclear Information System (INIS)

    Clausen, B.; Lee, S.Y.; Ustuendag, E.; Kim, C.P.; Brown, D.W.; Bourke, M.A.M.

    2006-01-01

    A bulk metallic glass matrix composite with dendritic second phase precipitates was investigated using neutron diffraction and self-consistent modeling (SCM) to ascertain its deformation mechanisms. The compressive behavior of both the composite and the second phase (in its monolithic form) were investigated. The diffraction data were compared to the predictions of a new SCM resulting in good agreement. For the first time, this model considered both amorphous and crystalline phases and allowed the calculation of single crystal elastic constants from polycrystalline diffraction data. It was shown that the ductile second phase yielded first upon loading, and this was followed by multiple shear band formation in the matrix, a process which enhanced the ductility of the composite

  7. In-situ fabrication of hybrid polyoxometalate nanoparticles composite films

    International Nuclear Information System (INIS)

    Lan Yang; Mao Baodong; Wang Enbo; Song Yonghai; Kang Zhenhui; Wang Chunlei; Tian Chungui; Zhang Chao; Xu Lin; Li Zhuang

    2007-01-01

    Inorganic-organic hybrid nanoparticles multilayer films were fabricated by extending the method of nucleation and growth of particles in polymer assemblies. The polyelectrolyte matrix was constructed by layer-by-layer self-assembly method. Synthesis of polyoxometalate nanoparticles was achieved by alternately dipping the precursor polyelectrolyte matrix into AgNO 3 and H 4 SiW 12 O 40 aqueous solutions. Repeating the above synthesis process, Ag 4 SiW 12 O 40 nanoparticles with controllable diameters of 20 to 77 nm were synthesized in the multilayer films in-situ. UV-vis absorption spectra indicate that the nanoparticles grew gradually in the synthesis process. Transmission electron microscopy was used to observe the size and morphology of the nanoparticles

  8. Soluble Lead and Bismuth Chalcogenidometallates: Versatile Solders for Thermoelectric Materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hao [Department; Son, Jae Sung [Department; School; Dolzhnikov, Dmitriy S. [Department; Filatov, Alexander S. [Department; Hazarika, Abhijit [Department; Wang, Yuanyuan [Department; Hudson, Margaret H. [Department; Sun, Cheng-Jun [Advanced; Chattopadhyay, Soma [Physical; Talapin, Dmitri V. [Department; Center

    2017-07-27

    Here we report the syntheses of largely unexplored lead and bismuth chalcogenidometallates in the solution phase. Using N2H4 as the solvent, new compounds such as K6Pb3Te6·7N2H4 were obtained. These soluble molecular compounds underwent cation exchange processes using resin chemistry, replacing Na+ or K+ by decomposable N2H5+ or tetraethylammonium cations. They also transformed into stoichiometric lead and bismuth chalcogenide nanomaterials with the addition of metal salts. Such a versatile chemistry led to a variety of composition-matched solders to join lead and bismuth chalcogenides and tune their charge transport properties at the grain boundaries. Solution-processed thin films composed of Bi0.5Sb1.5Te3 microparticles soldered by (N2H5)6Bi0.5Sb1.5Te6 exhibited thermoelectric power factors (~28 μW/cm K2) comparable to those in vacuum-deposited Bi0.5Sb1.5Te3 films. The soldering effect can also be integrated with attractive fabrication techniques for thermoelectric modules, such as screen printing, suggesting the potential of these solders in the rational design of printable and moldable thermoelectrics.

  9. Nanoscale size effect in in situ titanium based composites with cell viability and cytocompatibility studies

    Energy Technology Data Exchange (ETDEWEB)

    Miklaszewski, Andrzej, E-mail: andrzej.miklaszewski@put.poznan.pl [Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan (Poland); Jurczyk, Mieczysława U. [Division Mother' s and Child' s Health, Poznan University of Medical Sciences, Polna 33, 60-535 Poznan (Poland); Kaczmarek, Mariusz [Department of Immunology, Chair of Clinical Immunology, Poznan University of Medical Sciences, Rokietnicka 5D, 60-806 Poznan (Poland); Paszel-Jaworska, Anna; Romaniuk, Aleksandra; Lipińska, Natalia [Department of Clinical Chemistry and Molecular Diagnostics, Poznan University of Medical Sciences, Przybyszewskiego 49, 60-355 Poznan (Poland); Żurawski, Jakub [Department of Immunobiochemistry, Chair of Biology and Environmental Sciences, Poznan University of Medical Sciences, Rokietnicka 8, 60-806 Poznan (Poland); Urbaniak, Paulina [Department of Cell Biology, Poznan University of Medical Sciences, Rokietnicka 5D, 60-806 Poznan (Poland); Jurczyk, Mieczyslaw [Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan (Poland)

    2017-04-01

    Novel in situ Metal Matrix Nanocomposite (MMNC) materials based on titanium and boron, revealed their new properties in the nanoscale range. In situ nanocomposites, obtained through mechanical alloying and traditional powder metallurgy compaction and sintering, show obvious differences to their microstructural analogue. A unique microstructure connected with good mechanical properties reliant on the processing conditions favour the nanoscale range of results of the Ti-TiB in situ MMNC example. The data summarised in this work, support and extend the knowledge boundaries of the nanoscale size effect that influence not only the mechanical properties but also the studies on the cell viability and cytocompatibility. Prepared in the same bulk, in situ MMNC, based on titanium and boron, could be considered as a possible candidate for dental implants and other medical applications. The observed relations and research conclusions are transferable to the in situ MMNC material group. Aside from all the discussed relations, the increasing share of these composites in the ever-growing material markets, heavily depends on the attractiveness and a possible wider application of these composites as well as their operational simplicity presented in this work. - Highlights: • Nano and microscale size precursor influence the final composite microstructure and properties. • Obtained from the nanoscale precursor sinters, characterise with a uniform and highly dispersed microstructure • Mechanical properties favoured Nano scale size precursor • Boron addition could be significantly reduced for moderate properties range. • A possible candidate for dental implants and other medical applications.

  10. Low Cost Al-Si Casting Alloy As In-Situ Composite for High Temperature Applications

    Science.gov (United States)

    Lee, Jonathan A.

    2000-01-01

    A new aluminum-silicon (Al-Si) alloy has been successfully developed at NASA- Marshall Space Flight Center (MSFC) that has significant improvement in tensile and fatigue strength at elevated temperatures (500 F-700 F). The alloy offers a number of benefits such as light weight, high hardness, low thermal expansion and high surface wear resistance. In hypereutectic form, this alloy is considered as an in-situ Al-Si composite with tensile strength of about 90% higher than the auto industry 390 alloy at 600 F. This composite is very economically produced by using either conventional permanent steel molds or die casting. The projected material cost is less than $0.90 per pound, and automotive components such as pistons can be cast for high production rate using conventional casting techniques with a low and fully accounted cost. Key Words: Metal matrix composites, In-situ composite, aluminum-silicon alloy, hypereutectic alloy, permanent mold casting, die casting.

  11. Ultrafine-grained Al composites reinforced with in-situ Al3Ti filaments

    Czech Academy of Sciences Publication Activity Database

    Krizik, P.; Balog, M.; Nosko, M.; Riglos, M. V. C.; Dvořák, Jiří; Bajana, O.

    2016-01-01

    Roč. 657, MAR (2016), s. 6-14 ISSN 0921-5093 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Aluminum * Filament * In-situ metal matrix composite * Mechanical properties * Microstructure * Ultrafine-grained Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.094, year: 2016

  12. Spectroscopic investigation of oxidized solder surfaces

    International Nuclear Information System (INIS)

    Song, Jenn-Ming; Chang-Chien, Yu-Chien; Huang, Bo-Chang; Chen, Wei-Ting; Shie, Chi-Rung; Hsu, Chuang-Yao

    2011-01-01

    Highlights: → UV-visible spectroscopy is successfully used to evaluate the degree of discoloring of solders. → The surface oxides of solders can also be identified by UV-visible absorption spectra. → The discoloration of solder surface can be correlated with optical characterization of oxides. → A strategy against discoloring by alloying was also suggested. - Abstract: For further understanding of the discoloration of solder surfaces due to oxidation during the assembly and operation of electronic devices, UV-vis and X-ray photoelectron spectroscopic analyses were applied to evaluate the degree of discoloring and identify the surface oxides. The decrease in reflectance of the oxidized solder surface is related to SnO whose absorption band is located within the visible region. A trace of P can effectively depress the discoloration of solders under both solid and semi-solid states through the suppression of SnO.

  13. Subgrain Rotation Behavior in Sn3.0Ag0.5Cu-Sn37Pb Solder Joints During Thermal Shock

    Science.gov (United States)

    Han, Jing; Tan, Shihai; Guo, Fu

    2018-01-01

    Ball grid array (BGA) samples were soldered on a printed circuit board with Sn37Pb solder paste to investigate the recrystallization induced by subgrain rotation during thermal shock. The composition of the solder balls was Sn3.0Ag0.5Cu-Sn37Pb, which comprised mixed solder joints. The BGA component was cross-sectioned before thermal shock. The microstructure and grain orientations were obtained by a scanning electron microscope equipped with an electron back-scattered diffraction system. Two mixed solder joints at corners of the BGA component were selected as the subjects. The results showed that recrystallization occurred at the corner of the solder joints after 200 thermal shock cycles. The recrystallized subgrains had various new grain orientations. The newly generated grain orientations were closely related to the initial grain orientations, which indicated that different subgrain rotation behaviors could occur in one mixed solder joint with the same initial grain orientation. When the misorientation angles were very small, the rotation axes were about Sn [100], [010] and [001], as shown by analyzing the misorientation angles and subgrain rotation axes, while the subgrain rotation behavior with large misorientation angles in the solder joints was much more complicated. As Pb was contained in the solder joints and the stress was concentrated on the corner of the mixed solder joints, concaves and cracks were formed. When the adjacent recrystallized subgrains were separated, and the process of the continuous recrystallization was limited.

  14. Soldering of Mg Joints Using Zn-Al Solders

    Science.gov (United States)

    Gancarz, Tomasz; Berent, Katarzyna; Skuza, Wojciech; Janik, Katarzyna

    2018-04-01

    Magnesium has applications in the automotive and aerospace industries that can significantly contribute to greater fuel economy and environmental conservation. The Mg alloys used in the automotive industry could reduce mass by up to 70 pct, providing energy savings. However, alongside the advantages there are limitations and technological barriers to use Mg alloys. One of the advantages concerns phenomena occurring at the interface when joining materials investigated in this study, in regard to the effect of temperature and soldering time for pure Mg joints. Eutectic Zn-Al and Zn-Al alloys with 0.05 (wt pct) Li and 0.2 (wt pct) Na were used in the soldering process. The process was performed for 3, 5, and 8 minutes of contact, at temperatures of 425 °C, 450 °C, 475 °C, and 500 °C. Selected, solidified solder-substrate couples were cross-sectioned, and their interfacial microstructures were investigated by scanning electron microscopy. The experiment was designed to demonstrate the effect of time, temperature, and the addition of Li and Na on the kinetics of the dissolving Mg substrate. The addition of Li and Na to eutectic Zn-Al caused to improve mechanical properties. Higher temperatures led to reduced joint strength, which is caused by increased interfacial reaction.

  15. Ductile-phase toughening in V-V3Si in situ composites

    International Nuclear Information System (INIS)

    Henshall, G.; Strum, M.J.; Bewlay, B.P.; Sutliff, J.A.

    1997-01-01

    This article describes the room-temperature fracture behavior of ductile-phase-toughened V-V 3 Si in situ composites that were produced by arc melting (AM), cold-crucible induction melting (IM), and cold-crucible directional solidification (DS). Composites were produced containing a wide range of microstructures, interstitial impurity contents, and volume fractions of the ductile V-Si solid solution phase, denoted (V). The fracture toughness of these composites generally increases as the volume fraction of (V) increases, but is strongly influenced by the microstructure, the mechanical properties of the component phases, and the crystallographic orientation of the (V) phase with respect to the maximum principal stress direction. For eutectic composites that have a (V) volume fraction of about 50 pct, the fracture toughness increases with decreasing ''''effective'''' interstitial impurity concentration, [I] = [N] + 1.33 [O] + 9 [H]. As [I] decreases from 1,400 ppm (AM) to 400 ppm (IM), the fracture toughness of the eutectic composites increases from 10 to 20 MPa √m. Further, the fracture toughness of the DS eutectic composites is greater when the crack propagation direction is perpendicular, rather than parallel, to the composite growth direction. These results are discussed in light of conventional ductile-phase bridging theories, which alone cannot fully explain the fracture toughness of V-Si in situ composites

  16. Evaluation of carbon fiber composites modified by in situ incorporation of carbon nanofibers

    Directory of Open Access Journals (Sweden)

    André Navarro de Miranda

    2011-12-01

    Full Text Available Nano-carbon materials, such as carbon nanotubes and carbon nanofibers, are being thought to be used as multifunctional reinforcement in composites. The growing of carbon nanofiber at the carbon fiber/epoxy interface results in composites having better electrical properties than conventional carbon fiber/epoxy composites. In this work, carbon nanofibers were grown in situ over the surface of a carbon fiber fabric by chemical vapor deposition. Specimens of carbon fiber/nanofiber/epoxy (CF/CNF/epoxy composites were molded and electrical conductivity was measured. Also, the CF/CNF/epoxy composites were tested under flexure and interlaminar shear. The results showed an overall reduction in mechanical properties as a function of added nanofiber, although electrical conductivity increased up to 74% with the addition of nanofibers. Thus CF/CNF/epoxy composites can be used as electrical dissipation discharge materials.

  17. Thermodynamics parameters of nano-Ni/PS composites prepared by in situ polymerization method

    International Nuclear Information System (INIS)

    Liao Qilong; Xiong Jie; Ning Haixia

    2011-01-01

    Spherical nickel nanoparticles with about 75∼200 nm in size were obtained by a liquid reduction method. The nickel nanoparticles/PS composites were synthesized via in situ polymerization method. XRD, FTIR, SEM and TG-DSC were respectively used to measure the properties of nickel nanoparticles, the microstructure of as-prepared composites samples, the distribution of nickel nanoparticles in PS and the thermodynamic parameters of as-prepared composites. The results show that the nickel nanoparticles will enhance the glass transition temperature of nano-Ni/PS composites. The enthalpy of composites is heightened by increasing of doping dose, and it reaches the top when the doping dose is from 1% to 2%. The specific heat of the composites will reduce with the doping dose of nickel nanoparticles increasing. (authors)

  18. Electrochemical migration of lead-free solder alloys in Na2SO4 environment

    DEFF Research Database (Denmark)

    Medgyes, Balint; Ádám, Sándor; Tar, Lajos

    2017-01-01

    The effect of sulphate ion concentration on electrochemical migration of lead-free solder alloys was investigated with the use of water drop tests, by applying an in-situ optical and electrical inspection system. According to the Mean-Time-To-Failure (MTTF) values it was found that in the case of...

  19. A novel fabrication technology of in situ TiB2/6063Al composites: High energy ball milling and melt in situ reaction

    International Nuclear Information System (INIS)

    Zhang, S.-L.; Yang, J.; Zhang, B.-R.; Zhao, Y.-T.; Chen, G.; Shi, X.-X.; Liang, Z.-P.

    2015-01-01

    Highlights: • This paper presents a novel technology to fabricate the TiB 2 /6063Al composites. • The novel technology decreases in situ reaction temperature and shortens the time. • The reaction mechanism of in situ reaction at the low temperature is discussed. • Effect of ball milling time and in situ reaction time on the composites is studied. - Abstract: TiB 2 /6063Al matrix composites are fabricated from Al–TiO 2 –B 2 O 3 system by the technology combining high energy ball milling with melt in situ reaction. The microstructure and tensile properties of the composites are investigated by XRD, SEM, EDS, TEM and electronic tensile testing. The results indicate that high energy ball milling technology decreases the in situ reaction temperature and shortens the reaction time for Al–TiO 2 –B 2 O 3 system in contrast with the conventional melt in situ synthesis. The morphology of in situ TiB 2 particles is exhibited in irregular shape or nearly circular shape, and the average size of the particles is less than 700 nm, thereinto the minimum size is approximately 200 nm. In addition, the morphology and size of the reinforced particles are affected by the time of ball milling and in situ reaction. TEM images indicate that the interface between 6063Al matrix and TiB 2 particles is clear and no interfacial outgrowth is observed. Tensile testing results show that the as-cast TiB 2 /6063Al composites exhibit a much higher strength, reaching 191 MPa, which is 1.23 times as high as the as-cast 6063Al matrix. Besides, the tensile fracture surface of the composites displays the dimple-fracture character

  20. A novel fabrication technology of in situ TiB{sub 2}/6063Al composites: High energy ball milling and melt in situ reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.-L.; Yang, J. [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013 (China); Zhang, B.-R. [School of Mechanical Engineering, Qilu University of Technology, Jinan, Shandong 250022 (China); Zhao, Y.-T., E-mail: 278075525@qq.com [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013 (China); Chen, G.; Shi, X.-X.; Liang, Z.-P. [School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013 (China)

    2015-08-05

    Highlights: • This paper presents a novel technology to fabricate the TiB{sub 2}/6063Al composites. • The novel technology decreases in situ reaction temperature and shortens the time. • The reaction mechanism of in situ reaction at the low temperature is discussed. • Effect of ball milling time and in situ reaction time on the composites is studied. - Abstract: TiB{sub 2}/6063Al matrix composites are fabricated from Al–TiO{sub 2}–B{sub 2}O{sub 3} system by the technology combining high energy ball milling with melt in situ reaction. The microstructure and tensile properties of the composites are investigated by XRD, SEM, EDS, TEM and electronic tensile testing. The results indicate that high energy ball milling technology decreases the in situ reaction temperature and shortens the reaction time for Al–TiO{sub 2}–B{sub 2}O{sub 3} system in contrast with the conventional melt in situ synthesis. The morphology of in situ TiB{sub 2} particles is exhibited in irregular shape or nearly circular shape, and the average size of the particles is less than 700 nm, thereinto the minimum size is approximately 200 nm. In addition, the morphology and size of the reinforced particles are affected by the time of ball milling and in situ reaction. TEM images indicate that the interface between 6063Al matrix and TiB{sub 2} particles is clear and no interfacial outgrowth is observed. Tensile testing results show that the as-cast TiB{sub 2}/6063Al composites exhibit a much higher strength, reaching 191 MPa, which is 1.23 times as high as the as-cast 6063Al matrix. Besides, the tensile fracture surface of the composites displays the dimple-fracture character.

  1. Microstructure Characteristics of Fe-Matrix Composites Reinforced by In-Situ Carbide Particulates

    Science.gov (United States)

    Huang, Xiaodong; Song, Yanpei

    2017-10-01

    Carbide particulates reinforced iron-matrix composites were prepared by in-situ synthesis reaction between Ti, V and C on liquid alloys surface. The microstructure of the composite was characterized by SEM, TEM and OM. The results showed that the main phases were α-Fe, carbide particulate; besides, there were small amounts of γ-Fe and graphite (G) in the composite. The carbides were TiVC2 and VC in the shape of short bar and graininess. The matrix consisted of martensite and small amounts of retained austenite.

  2. NewIn-situ synthesis method of magnesium matrix composites reinforced with TiC particulates

    Directory of Open Access Journals (Sweden)

    Zhang Xiuqing

    2006-12-01

    Full Text Available Magnesium matrix composites reinforced with TiC particulates was prepared using a new in-situ synthesis method of remelting and dilution technique. And measurements were performed on the composites. The results of x ray diffraction (XRD analysis confirmed that TiC particulates were synthesized during the sintering process, and they retained in magnesium matrix composites after the remelting and dilution processing. From the microstructure characterization and electron probe microanalysis (EPMA, we could see that fine TiC particulates distributed uniformly in the matrix material.

  3. In situ observation of mechanical damage within a SiC-SiC ceramic matrix composite

    International Nuclear Information System (INIS)

    Saucedo-Mora, L.; Lowe, T.; Zhao, S.; Lee, P.D.; Mummery, P.M.; Marrow, T.J.

    2016-01-01

    SiC-SiC ceramic matrix composites are candidate materials for fuel cladding in Generation IV nuclear fission reactors and as accident tolerant fuel clad in current generation plant. Experimental methods are needed that can detect and quantify the development of mechanical damage, to support modelling and qualification tests for these critical components. In situ observations of damage development have been obtained of tensile and C-ring mechanical test specimens of a braided nuclear grade SiC-SiC ceramic composite tube, using a combination of ex situ and in situ computed X-ray tomography observation and digital volume correlation analysis. The gradual development of damage by matrix cracking and also the influence of non-uniform loading are examined. - Highlights: • X-ray tomography with digital volume correlation measures 3D deformation in situ. • Cracking and damage in the microstructure can be detected using the strain field. • Fracture can initiate from the monolithic coating of a SiC-SiC ceramic composite.

  4. In situ observation of mechanical damage within a SiC-SiC ceramic matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Saucedo-Mora, L. [Institute Eduardo Torroja for Construction Sciences-CSIC, Madrid (Spain); Department of Materials, University of Oxford (United Kingdom); Lowe, T. [Manchester X-ray Imaging Facility, The University of Manchester (United Kingdom); Zhao, S. [Department of Materials, University of Oxford (United Kingdom); Lee, P.D. [Research Complex at Harwell, Rutherford Appleton Laboratory (United Kingdom); Mummery, P.M. [School of Mechanical, Aerospace and Civil Engineering, The University of Manchester (United Kingdom); Marrow, T.J., E-mail: james.marrow@materials.ox.ac.uk [Department of Materials, University of Oxford (United Kingdom)

    2016-12-01

    SiC-SiC ceramic matrix composites are candidate materials for fuel cladding in Generation IV nuclear fission reactors and as accident tolerant fuel clad in current generation plant. Experimental methods are needed that can detect and quantify the development of mechanical damage, to support modelling and qualification tests for these critical components. In situ observations of damage development have been obtained of tensile and C-ring mechanical test specimens of a braided nuclear grade SiC-SiC ceramic composite tube, using a combination of ex situ and in situ computed X-ray tomography observation and digital volume correlation analysis. The gradual development of damage by matrix cracking and also the influence of non-uniform loading are examined. - Highlights: • X-ray tomography with digital volume correlation measures 3D deformation in situ. • Cracking and damage in the microstructure can be detected using the strain field. • Fracture can initiate from the monolithic coating of a SiC-SiC ceramic composite.

  5. Lead free solder mechanics and reliability

    CERN Document Server

    Pang, John Hock Lye

    2012-01-01

    Lead-free solders are used extensively as interconnection materials in electronic assemblies and play a critical role in the global semiconductor packaging and electronics manufacturing industry. Electronic products such as smart phones, notebooks and high performance computers rely on lead-free solder joints to connect IC chip components to printed circuit boards. Lead Free Solder: Mechanics and Reliability provides in-depth design knowledge on lead-free solder elastic-plastic-creep and strain-rate dependent deformation behavior and its application in failure assessment of solder joint reliability. It includes coverage of advanced mechanics of materials theory and experiments, mechanical properties of solder and solder joint specimens, constitutive models for solder deformation behavior; numerical modeling and simulation of solder joint failure subject to thermal cycling, mechanical bending fatigue, vibration fatigue and board-level drop impact tests. This book also: Discusses the mechanical prope...

  6. Study on the fabrication of Al matrix composites strengthened by combined in-situ alumina particle and in-situ alloying elements

    International Nuclear Information System (INIS)

    Huang Zanjun; Yang Bin; Cui Hua; Zhang Jishan

    2003-01-01

    A new idea to fabricate aluminum matrix composites strengthened by combined in-situ particle strengthening and in-situ alloying has been proposed. Following the concept of in-situ alloying and in-situ particle strengthening, aluminum matrix composites reinforced by Cu and α-Al 2 O 3 particulate (material I) and the same matrix reinforced by Cu, Si alloying elements and α-Al 2 O 3 particulate (material II) have been obtained. SEM observation, EDS and XRD analysis show that the alloy elements Cu and Si exist in the two materials, respectively. In-situ Al 2 O 3 particulates are generally spherical and their mean size is less than 0.5 μm. TEM observation shows that the in-situ α-Al 2 O 3 particulates have a good cohesion with the matrix. The reaction mechanism of the Al 2 O 3 particulate obtained by this method was studied. Thermodynamic considerations are given to the in-situ reactions and the distribution characteristic of in-situ the α-Al 2 O 3 particulate in the process of solidification is also discussed

  7. Flame retardancy of polyaniline-deposited paper composites prepared via in situ polymerization.

    Science.gov (United States)

    Wu, Xianna; Qian, Xueren; An, Xianhui

    2013-01-30

    Polyaniline-deposited paper composites doped with three inorganic acids were prepared via in situ polymerization, and their flame-retardant properties were investigated. Both the conductivity and flame retardancy of the composite increased with the increase of the amount of the polyaniline deposited. The doping acid played a very key role in both the conductivity and flame retardancy of the composite. The comprehensive properties of the composite could be improved when codoped with an equimolar mixture of H(3)PO(4) and H(2)SO(4) or H(3)PO(4) and HCl. The decay of the flame retardancy of the composite in atmosphere was due to the dedoping of the polyaniline deposited on cellulose fibers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Deformation and recrystallization of Nb-10Si in-situ composite

    International Nuclear Information System (INIS)

    Saqib, M.; Thirukkonda, M.; Cockeram, B.; Srinivasan, R.; Weiss, I.

    1993-01-01

    Materials for elevated temperature applications require a balance of strength, fracture toughness, mechanical and microstructural stability over the temperature range between room temperature and service temperatures which are expected to exceed 1,200 C, as well as oxidation and creep resistance. Recent trends indicate that Carbon/Carbon and Ceramic/Ceramic Composites do not meet all of these requirements. For example, carbon/carbon composites have good strength to density ratio, but inherently possess poor oxidation resistance, and SiC/SiC composites ha e excellent oxidation resistance, but are brittle over the entire temperature range of their stability. Ductile phase toughened composites with refractory intermetallic matrices are attractive alternatives. At service temperatures of about 1,200 C, most of the applied load will be carried by the intermetallic matrix phase, while the ductile (metallic) phase increases toughness by impeding crack propagation. As compared to other materials with potential for elevated temperature applications, mentioned above, these materials provide a better combination of elevated temperature strength and room temperature fracture toughness. Nb 10 a/o Si is a model material for ductile phase toughened in situ composites. In the as-cast condition the microstructure contains both the ductile metallic niobium phase and the continuous inter-metallic Nb 3 Si phase. The microstructure of this in situ composite can be tailored by thermomechanical processing (TMP). The changes in the morphology and spacing of the phases, and microstructural refinement following TMP, have been shown to improve the fracture toughness of the alloy. as compared to the as-cast material. Therefore, understanding of the deformation behavior and the mechanisms of recovery and recrystallization are of great importance in tailoring the microstructure of in situ composites by TMP

  9. Effects of Fe2NiO4 nanoparticles addition into lead free Sn–3.0Ag–0.5Cu solder pastes on microstructure and mechanical properties after reflow soldering process

    International Nuclear Information System (INIS)

    Chellvarajoo, Srivalli; Abdullah, M.Z.; Samsudin, Z.

    2015-01-01

    Highlights: • Fe 2 NiO 4 nanoparticles added into SAC 305 by mechanical mixing to form nanocomposite solder paste. • Nanoparticles in the composite solder travels with flux to the outermost surface after reflow. • The intermetallics compound reduced with the addition of nanoparticles into solder paste. • The hardness increased with the addition of limited percentage of nanoparticles into SAC 305. - Abstract: This study investigates the effects of the addition of Fe 2 NiO 4 nanoparticles into a SAC-305 lead-free solder paste. Iron, nickel, and oxide nano-elements were mixed with Pb-free solder alloying elements to produce a new form of nanocomposite solder paste, which can be a promising material in electronic packaging. The SAC-305 was mechanically added with 0.5, 1.5, and 2.5 wt.% of Fe 2 NiO 4 nanoparticles. The migration of nanoparticles in the nanocomposite solder paste to the outermost surface was clarified using the copper ‘sandwich’ method, which was performed after the reflow soldering process. Varying amounts of nanoparticles in the SAC-305 affected the IMC thickness and mechanical properties of the nanocomposite solder paste. The IMC thickness was reduced by 29.15%, 42.37%, and 59.00% after adding 0.5, 1.5, and 2.5 wt.% of Fe 2 NiO 4 nanoparticles in the SAC-305, respectively. However, via nanoindentation method, the hardness of the nanocomposite solder was improved by 44.07% and 56.82% after adding 0.5 and 1.5 wt.% of Fe 2 NiO 4 nanoparticles, respectively. If the addition of Fe 2 NiO 4 nanoparticle exceeded 1.5 wt.%, the hardness increased infinitely

  10. Investigation on solder joint strength of nickel tin-plated and CRS tabs with PCB

    International Nuclear Information System (INIS)

    Luay Hussain

    2002-01-01

    Failure analysis on easily peels off Nickel and CRS steel tabs from PCB was carried out. Nickel Tin plated tabs, CRS steel tabs and tube were joined to the PCB using reflow/ convection soldering, in an oven. The solder paste composition is Sn36/Pb35/Ag2. Peel test was conducted and it was found that many tabs could be easily peeled off with low force. Porosities which varies from 0.4 mm to < 0.01mm in diameter, developed during soldering process and solidification was noted. It was found, the number, size and position of these porosities inside the solder layer on both parts of the tabs affect the peel strength. Scanning Electron Microscopy study and EDX analysis were carried out. It was found that the low peel strength values were due to the combination of generation and development of porosities during soldering process which act as stress concentrators and the evolution (growth) of eutectic Sn/Pb and Sn/Ni/Cu brittle grainy phase. Large eutectic microstructure with brittle Sn-Ni-Cu grainy phase enhances the failure with low peeling forces. Sample showing no feature of Sn/Ni/Cu grain gave high peeling strength value. Solder reflow, an important process, can result in strength enhancement (if it was controlled for example in a furnace). (Author)

  11. TiB2 reinforced aluminum based in situ composites fabricated by stir casting

    International Nuclear Information System (INIS)

    Chen, Fei; Chen, Zongning; Mao, Feng; Wang, Tongmin; Cao, Zhiqiang

    2015-01-01

    In this study, a new technique involving mechanical stirring at the salts/aluminum interface was developed to fabricate TiB 2 particulate reinforced aluminum based in situ composites with improved particle distribution. Processing parameters in terms of stirring intensity, stirring duration and stirring start time were optimized according to the microstructure and mechanical properties evaluation. The results show that, the first and last 15 min of the entire 60 min holding are of prime importance to the particle distribution of the final composites. When applying 180 rpm (revolutions per minute) stirring at the salts/aluminum interface in these two intervals, a more uniform microstructure can be achieved and the Al-4 wt% TiB 2 composite thus produced exhibits superior mechanical performance. Synchrotron radiation X-ray computed tomography (SR-CT) was used to give a full-scale imaging of the particle distribution. From the SR-CT results, the in situ Al–xTiB 2 composites (x=1, 4 and 7, all in wt%) fabricated by the present technique are characterized by fine and clean TiB 2 particles distributed uniformly throughout the Al matrix. These composites not only have higher yield strength (σ 0.2 ) and ultimate tensile strength (UTS), but also exhibit superior ductility, with respect to the Al–TiB 2 composites fabricated by the conventional process. The σ 0.2 and UTS of the Al–7TiB 2 composite in the present work, are 260% and 180% higher than those of the matrix. A combined mechanism was also presented to interpret the improvements in yield strength of the composites as influenced by their microstructures and processing history. The predicted values are in good agreement with the experimental results, strongly supporting the strengthening mechanism we proposed. Fractography reveals that the composites thus fabricated, follow ductile fracture mechanism in spite of the presence of stiff reinforcements

  12. Nano-soldering to single atomic layer

    Science.gov (United States)

    Girit, Caglar O [Berkeley, CA; Zettl, Alexander K [Kensington, CA

    2011-10-11

    A simple technique to solder submicron sized, ohmic contacts to nanostructures has been disclosed. The technique has several advantages over standard electron beam lithography methods, which are complex, costly, and can contaminate samples. To demonstrate the soldering technique graphene, a single atomic layer of carbon, has been contacted, and low- and high-field electronic transport properties have been measured.

  13. Safer Soldering Guidelines and Instructional Resources

    Science.gov (United States)

    Love, Tyler S.; Tomlinson, Joel

    2018-01-01

    Soldering is a useful and necessary process for many classroom, makerspace, Fab Lab, technology and engineering lab, and science lab activities. As described in this article, soldering can pose many safety risks without proper engineering controls, standard operating procedures, and direct instructor supervision. There are many safety hazards…

  14. A STUDY ON MICROSTRUCTURE CHARACTERISTICS OF IN SITU FORMED TiC REINFORCED COMPOSITE COATINGS

    OpenAIRE

    PENG LIU; WEI GUO; HUI LUO

    2012-01-01

    In situ synthesized TiC reinforced composite coating was fabricated by laser cladding of Al-Ni-Cr-C powders on titanium alloys, which can greatly improve the surface performance of the substrate. In this study, the Al-Ni-Cr-C laser-cladded composite coatings have been researched by means of X-ray diffraction, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). There was a metallurgical combination between the Al-Ni-Cr-C laser-cladded coating and the Ti-6Al-4V substrat...

  15. On the oxidation behaviour of a Cu-10 vol% Cr in situ composite

    International Nuclear Information System (INIS)

    Haugsrud, R.; Lee, K.L.

    2005-01-01

    The oxidation behaviour of copper and Cu-10 vol% Cr in situ composite was studied at 400-700 deg. C in air and in argon containing 10 ppm O 2 . Oxidation kinetics was investigated by means of isothermal thermogravimetry and the oxide scales were characterized by scanning electron microscopy (SEM). The presence of the chromium fibres increases the oxidation resistance compared to unalloyed copper up to 600 deg. C. The oxidation mechanism and the influence of the different oxidation phenomena on the creep characteristics of the alloy composite are discussed

  16. Magnetization of in situ multifilamentary superconducting Nb3Sn-Cu composites

    International Nuclear Information System (INIS)

    Shen, S.S.; Verhoeven, J.D.

    1980-01-01

    Magnetic properties are reported for in situ superconducting Nb 3 Sn composites that have exhibited attractive electrical properties and superior mechanical characteristics. Magnetization measurements were conducted up to 4 T at 4.2 K on a variety of samples of different sizes and twist pitches, and the results are presented in absolute M-H curves and losses per cycle. It is observed that the magnetization of such composites is generally proportional to the size of the wire (approx. 0.25 to 0.51 mm) rather than the fiber size (approx. 10 -7 m), which indicates a strong coupling effect among Nb 3 Sn fibers

  17. Features of soldering of molybdenum a lols

    International Nuclear Information System (INIS)

    Grishin, V.L.; Rybkin, B.V.; Cherkasov, A.F.

    1980-01-01

    Soldering features of complex-alloy molybdenum alloys were investigated in comparison with alloys based on solid solutions. Soldering features of heterogeneous molybdenum base alloys were investigated using samples of 0.5-1.O mm sheets with the strain of about 95% made of ingots which had been smelted in arc vacuum furnaces. The soldering of samples was carried out in 5x1O -5 mm Hg vacuum using different sources of heating: radiation, electron-ray and contact. It was shown that heat-resisting soldered joints of heterogeneous molybdenum alloys could be produced using zirconium and niobium base solders containing the most effective hardeners of the parent material (titanum, vanadium, tantalum, molybdenum, tungsten). To preserve high mechanical properties of heterogeneous alloys it was expedient to use for welding local heating sources which permitted to decrease considerably temperature- time conditions of the process

  18. Laser cladding of in situ TiB2/Fe composite coating on steel

    International Nuclear Information System (INIS)

    Du Baoshuai; Zou Zengda; Wang Xinhong; Qu Shiyao

    2008-01-01

    To enhance the wear resistance of mechanical components, laser cladding has been applied to deposit in situ TiB 2 /Fe composite coating on steel using ferrotitanium and ferroboron as the coating precursor. The phase constituents and microstructure of the composite coating were investigated using X-ray diffraction (XRD), scanning electron micrograph (SEM) and electron probe microanalysis (EPMA). Microhardness tester and block-on-ring wear tester were employed to measure the microhardness and dry-sliding wear resistance of the composite coating. Results show that defect-free composite coating with metallurgical joint to the steel substrate can be obtained. Phases presented in the coating consist of TiB 2 and α-Fe. TiB 2 particles which are formed in situ via nucleation-growth mechanism are distributed uniformly in the α-Fe matrix with blocky morphology. The microhardness and wear properties of the composite coating improved significantly in comparison to the as-received steel substrate due to the presence of the hard reinforcement TiB 2

  19. Laser cladding of in situ TiB{sub 2}/Fe composite coating on steel

    Energy Technology Data Exchange (ETDEWEB)

    Du Baoshuai; Zou Zengda [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Wang Xinhong [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)], E-mail: xinhongwang@sdu.edu.cn; Qu Shiyao [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)

    2008-08-15

    To enhance the wear resistance of mechanical components, laser cladding has been applied to deposit in situ TiB{sub 2}/Fe composite coating on steel using ferrotitanium and ferroboron as the coating precursor. The phase constituents and microstructure of the composite coating were investigated using X-ray diffraction (XRD), scanning electron micrograph (SEM) and electron probe microanalysis (EPMA). Microhardness tester and block-on-ring wear tester were employed to measure the microhardness and dry-sliding wear resistance of the composite coating. Results show that defect-free composite coating with metallurgical joint to the steel substrate can be obtained. Phases presented in the coating consist of TiB{sub 2} and {alpha}-Fe. TiB{sub 2} particles which are formed in situ via nucleation-growth mechanism are distributed uniformly in the {alpha}-Fe matrix with blocky morphology. The microhardness and wear properties of the composite coating improved significantly in comparison to the as-received steel substrate due to the presence of the hard reinforcement TiB{sub 2}.

  20. Biomimetic composite microspheres of collagen/chitosan/nano-hydroxyapatite: In-situ synthesis and characterization.

    Science.gov (United States)

    Teng, Shu-Hua; Liang, Mian-Hui; Wang, Peng; Luo, Yong

    2016-01-01

    The collagen/chitosan/hydroxyapatite (COL/CS/HA) composite microspheres with a good spherical form and a high dispersity were successfully obtained using an in-situ synthesis method. The FT-IR and XRD results revealed that the inorganic phase in the microspheres was crystalline HA containing carbonate ions. The morphology of the composite microspheres was dependent on the HA content, and a more desirable morphology was achieved when 20 wt.% HA was contained. The composite microspheres exhibited a narrow particle distribution, most of which ranged from 5 to 10 μm. In addition, the needle-like HA nano-particles were uniformly distributed in the composite microspheres, and their crystallinity and crystal size decreased with the HA content. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Fibrillar polyaniline/diatomite composite synthesized by one-step in situ polymerization method

    International Nuclear Information System (INIS)

    Li Xingwei; Li Xiaoxuan; Wang Gengchao

    2005-01-01

    A fibrillar polyaniline/diatomite composite was prepared by one-step in situ polymerization of aniline in the dispersed system of diatomite, and was characterized via Fourier-transform infrared spectra (FT-IR), UV-vis-NIR spectra, wide-angle X-ray diffraction (WXRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM), as well as conductivity. Morphology of the composite is uniform nanofibers, which the diameters of nanofibers are about 50-80 nm. The conductivity of polyaniline/diatomite composite contained 28% polyaniline is 0.29 S cm -1 at 25 deg. C, and temperature of thermal degradation has reached 493 deg. C in air. The composite has potential commercial applications as fillers for electromagnetic shielding materials and conductive coatings

  2. Effect of trace elements on the interface reactions between two lead-free solders and copper or nickel substrates

    Directory of Open Access Journals (Sweden)

    Soares D.

    2007-01-01

    Full Text Available Traditional Sn-Pb solder alloys are being replaced, because of environmental and health concerns about lead toxicity. Among some alternative alloy systems, the Sn-Zn and Sn-Cu base alloy systems have been studied and reveal promising properties. The reliability of a solder joint is affected by the solder/substrate interaction and the nature of the layers formed at the interface. The solder/substrate reactions, for Sn-Zn and Sn-Cu base solder alloys, were evaluated in what concerns the morphology and chemical composition of the interface layers. The effect of the addition of P, at low levels, on the chemical composition of the layers present at the interface was studied. The phases formed at the interface between the Cu or Ni substrate and a molten lead-free solder at 250ºC, were studied for different stage times and alloy compositions. The melting temperatures, of the studied alloys, were determined by Differential Scanning Calorimetry (DSC. Identification of equilibrium phases formed at the interface layer, and the evaluation of their chemical composition were performed by Scanning Electron Microscopy (SEM/EDS. Different interface characteristics were obtained, namely for the alloys containing Zn. The obtained IML layer thickness was compared, for both types of alloy systems.

  3. Photothermal effects of laser tissue soldering

    International Nuclear Information System (INIS)

    McNally, K.M.; Sorg, B.S.; Welch, A.J.; Dawes, J.M.; Owen, E.R.

    1999-01-01

    Low-strength anastomoses and thermal damage of tissue are major concerns in laser tissue welding techniques where laser energy is used to induce thermal changes in the molecular structure of the tissues being joined, hence allowing them to bond together. Laser tissue soldering, on the other hand, is a bonding technique in which a protein solder is applied to the tissue surfaces to be joined, and laser energy is used to bond the solder to the tissue surfaces. The addition of protein solders to augment tissue repair procedures significantly reduces the problems of low strength and thermal damage associated with laser tissue welding techniques. Investigations were conducted to determine optimal solder and laser parameters for tissue repair in terms of tensile strength, temperature rise and damage and the microscopic nature of the bonds formed. An in vitro study was performed using an 808 nm diode laser in conjunction with indocyanine green (ICG)-doped albumin protein solders to repair bovine aorta specimens. Liquid and solid protein solders prepared from 25% and 60% bovine serum albumin (BSA), respectively, were compared. The efficacy of temperature feedback control in enhancing the soldering process was also investigated. Increasing the BSA concentration from 25% to 60% greatly increased the tensile strength of the repairs. A reduction in dye concentration from 2.5mgml -1 to 0.25mgml -1 was also found to result in an increase in tensile strength. Increasing the laser irradiance and thus surface temperature resulted in an increased severity of histological injury. Thermal denaturation of tissue collagen and necrosis of the intimal layer smooth muscle cells increased laterally and in depth with higher temperatures. The strongest repairs were produced with an irradiance of 6.4Wcm -2 using a solid protein solder composed of 60% BSA and 0.25mgml -1 ICG. Using this combination of laser and solder parameters, surface temperatures were observed to reach 85±5 deg. C with a

  4. Solderability study of RABiTS-based YBCO coated conductors

    International Nuclear Information System (INIS)

    Zhang Yifei; Duckworth, Robert C.; Ha, Tam T.; Gouge, Michael J.

    2011-01-01

    Study examines the implication of solder and flux selection in YBCO splice joints. Focus is on commercially available RABiTS-based YBCO coated conductors. Solderability varied with solder and flux for three different stabilizations tested. Resistivity of stabilizer was dominant factor in splice joint resistance. Solder materials affected splice joint resistance when solderability was poor. The solderability of commercially available YBa 2 Cu 3 O 7-x (YBCO) coated conductors that were made from Rolling Assisted Biaxially Textured Substrates (RABiTS)-based templates was studied. The coated conductors, also known as second-generation (2G) high temperature superconductor (HTS) wires (in the geometry of flat tapes about 4 mm wide), were laminated with copper, brass, or stainless steel strips as stabilizers. To understand the factors that influence their solderability, surface profilometry and scanning electron microscopy were used to characterize the wire surfaces. The solderability of three solders, 52In48Sn, 67Bi33In, and 100In (wt.%), was evaluated using a standard test (IPC/ECA J-STD-002) and with two different commercial fluxes. It was found that the solderability varied with the solder and flux but the three different wires showed similar solderability for a fixed combination of solder and flux. Solder joints of the 2G wires were fabricated using the tools and the procedures recommended by the HTS wire manufacturer. The solder joints were made in a lap-joint geometry and with the superconducting sides of the two wires face-to-face. The electrical resistances of the solder joints were measured at 77 K, and the results were analyzed to qualify the soldering materials and evaluate the soldering process. It was concluded that although the selection of soldering materials affected the resistance of a solder joint, the resistivity of the stabilizer was the dominant factor.

  5. Effect of aging hardening on in situ synthesis magnesium matrix composites

    International Nuclear Information System (INIS)

    Zhang Xiuqing; Liao Lihua; Ma Naiheng; Wang Haowei

    2006-01-01

    Magnesium matrix composites reinforced with TiC particulates was synthesized using in situ synthesis technique. The result of XRD revealed the presence of TiC in precursor blocks and TiC/AZ91 composites. Effect of aging hardening on the composites was described using Brinell hardness measurements and scanning electron microscopy (SEM). The results revealed that the aging hardening peak of TiC/AZ91 composite appeared earlier comparatively with that of AZ91 magnesium alloy. And the appearance of aging hardening peak was earlier under the higher aging temperature such as 200 deg. C. The precipitating behavior of Mg 17 Al 12 phase in AZ91 alloy and TiC/AZ91 composites was described. Little discontinuous was discovered in the composites, and the amount of continuous precipitate in the composite matrix is smaller comparatively to that of AZ91 alloy. These results were analyzed with the fine grain size, much more interface between TiC and magnesium and high-density dislocation in magnesium matrix, which was contributed to the addition of TiC particulates

  6. Mechanical properties enhancement and microstructure study of Al-Si-TiB2 in situ composites

    Science.gov (United States)

    Sahoo, S. K.; Majhi, J.; Pattnaik, A. B.; Sahoo, J. K.; Das, Swagat

    2018-03-01

    Al–Si alloy-based composite is one of the most promising MMC materials owing to its outstanding mechanical properties, wear and corrosion resistance, low cost and ability to be synthesized via conventional casting routes. Challenges in achieving clean interface between reinforced particles and matrix alloy have been overcome by means of in-situ techniques of fabrication. Present investigation is concerned with synthesizing Al-Si-TiB2 in-situ composites through stir casting route using K2TiF6 and KBF4 halide salts for exothermic salt metal reaction. X-Ray diffraction analysis revealed the existence of TiB2 in the prepared samples. Effect of TiB2in-situ particles in the Al-Si base alloy has been investigated from the results obtained from optical microscopy as well as SEM study and wear analysis with a pin on disc wear testing apparatus. Improved hardness and wear properties were observed with addition of TiB2.

  7. The constitutive response of three solder materials

    International Nuclear Information System (INIS)

    Perez-Bergquist, Alejandro G.; Cao Fang; Perez-Bergquist, Sara J.; Lopez, Mike F.; Trujillo, Carl P.; Cerreta, Ellen K.; Gray, George T.

    2012-01-01

    Highlights: ► The full constitutive response of three solder materials. ► Test temperatures from −196 °C to 60 °C and strain rates from 10 −3 to >10 3 s −1 . ► Substitutes for leaded solders from a mechanical/microstructural properties view. - Abstract: As increasing worldwide demand for portable consumer electronics drives development of smaller, faster, more powerful electronic devices, components in these devices must become smaller, more precise, and more robust. Often, failure of these devices comes as a result of failure of the package (i.e. when a mobile phone is dropped) and specifically comes as a result of failure of solder interconnects. As a result, stronger more reliable solder materials are needed. In this paper, the constitutive responses of three solder materials (Sn63Pb37, Sn62Pb36Ag2, and Sn96.5Ag3Cu0.5) are analyzed as a function of temperature (−196 °C to 60 °C) and strain rate (10 −3 to >10 3 s −1 ). The lead-free Sn96.5Ag3Cu0.5 possessed the highest yield stress of the three solders at all tested strain rates and temperatures, and all solder microstructures which displayed a mechanical response that was sensitive to temperature exhibited grain coarsening with increasing plastic strain, even at room temperature.

  8. The constitutive response of three solder materials

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Bergquist, Alejandro G., E-mail: alexpb@lanl.gov [Materials Science and Technology Division, Los Alamos National Laboratory, Mail Stop G755, Los Alamos, NM 87545 (United States); Cao Fang [Exxon Mobil Research and Engineering Company, Annadale, NJ 08801 (United States); Perez-Bergquist, Sara J.; Lopez, Mike F.; Trujillo, Carl P.; Cerreta, Ellen K.; Gray, George T. [Materials Science and Technology Division, Los Alamos National Laboratory, Mail Stop G755, Los Alamos, NM 87545 (United States)

    2012-05-25

    Highlights: Black-Right-Pointing-Pointer The full constitutive response of three solder materials. Black-Right-Pointing-Pointer Test temperatures from -196 Degree-Sign C to 60 Degree-Sign C and strain rates from 10{sup -3} to >10{sup 3} s{sup -1}. Black-Right-Pointing-Pointer Substitutes for leaded solders from a mechanical/microstructural properties view. - Abstract: As increasing worldwide demand for portable consumer electronics drives development of smaller, faster, more powerful electronic devices, components in these devices must become smaller, more precise, and more robust. Often, failure of these devices comes as a result of failure of the package (i.e. when a mobile phone is dropped) and specifically comes as a result of failure of solder interconnects. As a result, stronger more reliable solder materials are needed. In this paper, the constitutive responses of three solder materials (Sn63Pb37, Sn62Pb36Ag2, and Sn96.5Ag3Cu0.5) are analyzed as a function of temperature (-196 Degree-Sign C to 60 Degree-Sign C) and strain rate (10{sup -3} to >10{sup 3} s{sup -1}). The lead-free Sn96.5Ag3Cu0.5 possessed the highest yield stress of the three solders at all tested strain rates and temperatures, and all solder microstructures which displayed a mechanical response that was sensitive to temperature exhibited grain coarsening with increasing plastic strain, even at room temperature.

  9. In situ observations of microscale damage evolution in unidirectional natural fibre composites

    DEFF Research Database (Denmark)

    Rask, Morten; Madsen, Bo; Sørensen, Bent F.

    2012-01-01

    Synchrotron X-ray tomographic microscopy (XTM) has been used to observe in situ damage evolution in unidirectional flax fibre yarn/polypropylene composites loaded in uniaxial tension at stress levels between 20% and 95% of the ultimate failure stress. XTM allows for 3D visualization of the internal...... damage state at each stress level. The overall aim of the study is to gain a better understanding of the damage mechanisms in natural fibre composites. This is necessary if they are to be optimized to fulfil their promising potential. Three dominating damage mechanisms have been identified: (i) interface...... splitting cracks typically seen at the interfaces of bundles of unseparated fibres, (ii) matrix shear cracks, and (iii) fibre failures typically seen at fibre defects. Based on the findings in the present study, well separated fibres with a low number of defects are recommended for composite reinforcements....

  10. Compositional Simulation of In-Situ Combustion EOR: A Study of Process Characteristics

    DEFF Research Database (Denmark)

    Jain, Priyanka; Stenby, Erling Halfdan; von Solms, Nicolas

    2010-01-01

    In order to facilitate the study of the influence of reservoir process characteristics in In-Situ combustion modeling and advance the work of Kristensen et al. in this domain; a fully compositional In-situ combustion (ISC) model of Virtual Kinetic Cell (VKC; single-cell model) for laboratory scale....... This incorporates fourteen pseudo components and fourteen reactions (distributed amongst thermal cracking, low temperature oxidation and high temperature oxidation). The paper presents a set of derivative plots indicating that reservoir process characterization in terms of thermal behavior of oil can be well...... construed in terms of thermo-oxidative sensitivity of SARA fractions. It can be interpreted from the results that operating parameters like air injection rate, oxygen feed concentration and activation energy have significant influence on oil recovery; an increase in air injection rate can lead to cooling...

  11. Thermomechanical Behavior of Monolithic SN-AG-CU Solder and Copper Fiber Reinforced Solders

    National Research Council Canada - National Science Library

    Reuse, Rolando

    2005-01-01

    .... The thermomechanical cycling in the solder causes numerous reliability challenges, mostly because of the mismatch of the coefficient of thermal expansion between the silicon chip and the substrate...

  12. In situ mesophase transformation by zirconium chloride in fabrication of carbon/carbon composites

    International Nuclear Information System (INIS)

    Zhang, Bo; Song, Huaihe; Chen, Xiaohong; Ma, Zhaokun; Yang, Xiaoguang; Xu, Zhenghui

    2012-01-01

    Carbon/carbon (C/C) composites were prepared using multiple cycle in situ mesophase densification in the presence of zirconium chloride. The mesophase transformation and the performance of C/C composites were investigated in detail. The results show that higher amount of ZrCl 4 and longer soaking time accelerate the condensation of aromatic hydrocarbons. Additionally, the XRD pattern and ash contents show that the ZrCl 4 is retained in the samples and transformed to t-ZrO 2 and m-ZrO 2 after carbonization. In all the composites, the bulk density increases with cycle times, and the flexural strength increases with bulk density. However, a decrease of flexural strength for low density composites was observed when increasing ZrCl 4 concentrations. This tendency is attributed to more ZrO 2 formation in the composites using 20 wt.% ZrCl 4 . Subsequently, these ZrO 2 particles produce interface defects in the matrix which decreases its strength. Attributed to the very low content of ZrO 2 in high density composites, there is no difference between the samples using 13 wt.% and 20 wt.% ZrCl 4 .

  13. Microstructure and wear resistance of in situ porous TiO/Cu composites

    Science.gov (United States)

    Qin, Qingdong; Huang, Bowei; Li, Wei

    2016-07-01

    An in situ porous TiO/Cu composite is successfully prepared using powder metallurgy by the reaction of Ti2CO and Cu powder. Morphological examination of the composite shows that the porosity of composites lies in the range between 10.2% and 35.2%. Dry sliding un-lubricated wear tests show that the wear resistance of the composite is higher than that of the Cu-Al alloy ingot. The coefficient of friction test shows that, as the volume fraction of the reinforced phase increases, the coefficient of friction decreases. The wear rate variation trend of the oil-lubricated wear test results is similar to that of the un-lubricated wear test results. The coefficient of friction for oil lubrication is similar for different volume fractions of the reinforced phase. The wear resistance of the composite at a sliding velocity of 200 rpm is slightly larger than that at 50 rpm. The porosity of the composites enhances the high-velocity oil-lubricated sliding wear resistance.

  14. In-Situ Preparation and Magnetic Properties of Fe3O4/WOOD Composite

    Science.gov (United States)

    Gao, Honglin; Zhang, Genlin; Wu, Guoyuan; Guan, Hongtao

    2011-06-01

    Fe3O4/wood composite, a magnetic material, was prepared by In-situ chemosynthesis method at room temperature. The X-ray diffraction (XRD) shows that the average partical size of Fe3O4 was about 14 nm. The magnetic properties of the resulting composites were investigated by vibrating sample magnetometer (VSM). The composites have saturation magnetization (Ms) values from 4.7 to 25.3 emu/g with the increase of weight percent gains (WPG) of the wood for the composites, but coercive forces (Hc) are invariable, which is different from the magnetic materials reported before. It may be due to the fact that the interaction between wood and Fe3O4 becomes stronger when less of Fe3O4 particles are introduced in the composition, and this also changes the surface anisotropy (Ks) of the magnetism. A structural characterization by Fourier transform infrared (FTIR) proved the interaction between Fe3O4 particles and wood matrix, and it also illustrates that this interaction influences the coercive force of the composite.

  15. Preparation of in situ hardening composite microcarriers: Calcium phosphate cement combined with alginate for bone regeneration

    Science.gov (United States)

    Park, Jung-Hui; Lee, Eun-Jung; Knowles, Jonathan C

    2014-01-01

    Novel microcarriers consisting of calcium phosphate cement and alginate were prepared for use as three-dimensional scaffolds for the culture and expansion of cells that are effective for bone tissue engineering. The calcium phosphate cement-alginate composite microcarriers were produced by an emulsification of the composite aqueous solutions mixed at varying ratios (calcium phosphate cement powder/alginate solution = 0.8–1.2) in an oil bath and the subsequent in situ hardening of the compositions during spherodization. Moreover, a porous structure could be easily created in the solid microcarriers by soaking the produced microcarriers in water and a subsequent freeze-drying process. Bone mineral-like apatite nanocrystallites were shown to rapidly develop on the calcium phosphate cement–alginate microcarriers under moist conditions due to the conversion of the α-tricalcium phosphate phase in the calcium phosphate cement into a carbonate–hydroxyapatite. Osteoblastic cells cultured on the microspherical scaffolds were proven to be viable, with an active proliferative potential during 14 days of culture, and their osteogenic differentiation was confirmed by the determination of alkaline phosphatase activity. The in situ hardening calcium phosphate cement–alginate microcarriers developed herein may be used as potential three-dimensional scaffolds for cell delivery and tissue engineering of bone. PMID:23836845

  16. Novel in situ coordinated cerium salt/acrylonitrile-butadiene rubber composite

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jianjun [Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Lu, Haifeng, E-mail: lhf@sdu.edu.cn [Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Zhang, Jie [Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Feng, Shengyu, E-mail: fsy@sdu.edu.cn [Key Laboratory of Special Functional Aggregated Materials, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2012-09-14

    A novel rubber composite of acrylonitrile-butadiene rubber (NBR) filled with cerium salt particles was vulcanized via in situ coordination for the first time. The resulting materials exhibit good mechanical properties. Curing characteristics analysis, differential scanning calorimetry, X-ray photoelectron spectroscopy, tensile testing, and an equilibrium swelling method were used for the characterization of the composite. The results in this paper indicate that the composite is a kind of elastomer based on the in situ coordination crosslinking interactions between the nitrile groups (-CN) of NBR and cerium ions. The mechanical properties of vulcanized cerium salt/ NBR rubber are altered when changing the sorts of cerium salt. Moreover, these materials show good irradiation resistance because of the introduction of the cerium salt. -- Highlights: Black-Right-Pointing-Pointer Cerium salts were firstly used to vulcanize the acrylonitrile-butadiene rubber. Black-Right-Pointing-Pointer Cerium salts act as not only crosslink agents but also reinforcing fillers in the matrix. Black-Right-Pointing-Pointer These materials show good irradiation resistance and mechanical properties at same time.

  17. Novel in situ coordinated cerium salt/acrylonitrile-butadiene rubber composite

    International Nuclear Information System (INIS)

    Han, Jianjun; Lu, Haifeng; Zhang, Jie; Feng, Shengyu

    2012-01-01

    A novel rubber composite of acrylonitrile-butadiene rubber (NBR) filled with cerium salt particles was vulcanized via in situ coordination for the first time. The resulting materials exhibit good mechanical properties. Curing characteristics analysis, differential scanning calorimetry, X-ray photoelectron spectroscopy, tensile testing, and an equilibrium swelling method were used for the characterization of the composite. The results in this paper indicate that the composite is a kind of elastomer based on the in situ coordination crosslinking interactions between the nitrile groups (–CN) of NBR and cerium ions. The mechanical properties of vulcanized cerium salt/ NBR rubber are altered when changing the sorts of cerium salt. Moreover, these materials show good irradiation resistance because of the introduction of the cerium salt. -- Highlights: ► Cerium salts were firstly used to vulcanize the acrylonitrile-butadiene rubber. ► Cerium salts act as not only crosslink agents but also reinforcing fillers in the matrix. ► These materials show good irradiation resistance and mechanical properties at same time.

  18. Data on a Laves phase intermetallic matrix composite in situ toughened by ductile precipitates.

    Science.gov (United States)

    Knowles, Alexander J; Bhowmik, Ayan; Purkayastha, Surajit; Jones, Nicholas G; Giuliani, Finn; Clegg, William J; Dye, David; Stone, Howard J

    2017-10-01

    The data presented in this article are related to the research article entitled "Laves phase intermetallic matrix composite in situ toughened by ductile precipitates" (Knowles et al.) [1]. The composite comprised a Fe 2 (Mo, Ti) matrix with bcc (Mo, Ti) precipitated laths produced in situ by an aging heat treatment, which was shown to confer a toughening effect (Knowles et al.) [1]. Here, details are given on a focused ion beam (FIB) slice and view experiment performed on the composite so as to determine that the 3D morphology of the bcc (Mo, Ti) precipitates were laths rather than needles. Scanning transmission electron microscopy (S(TEM)) micrographs of the microstructure as well as energy dispersive X-ray spectroscopy (EDX) maps are presented that identify the elemental partitioning between the C14 Laves matrix and the bcc laths, with Mo rejected from the matrix into laths. A TEM selected area diffraction pattern (SADP) and key is provided that was used to validate the orientation relation between the matrix and laths identified in (Knowles et al.) [1] along with details of the transformation matrix determined.

  19. Data on a Laves phase intermetallic matrix composite in situ toughened by ductile precipitates

    Directory of Open Access Journals (Sweden)

    Alexander J. Knowles

    2017-10-01

    Full Text Available The data presented in this article are related to the research article entitled “Laves phase intermetallic matrix composite in situ toughened by ductile precipitates” (Knowles et al. [1]. The composite comprised a Fe2(Mo, Ti matrix with bcc (Mo, Ti precipitated laths produced in situ by an aging heat treatment, which was shown to confer a toughening effect (Knowles et al. [1]. Here, details are given on a focused ion beam (FIB slice and view experiment performed on the composite so as to determine that the 3D morphology of the bcc (Mo, Ti precipitates were laths rather than needles. Scanning transmission electron microscopy (S(TEM micrographs of the microstructure as well as energy dispersive X-ray spectroscopy (EDX maps are presented that identify the elemental partitioning between the C14 Laves matrix and the bcc laths, with Mo rejected from the matrix into laths. A TEM selected area diffraction pattern (SADP and key is provided that was used to validate the orientation relation between the matrix and laths identified in (Knowles et al. [1] along with details of the transformation matrix determined.

  20. Microstructure of in-situ Synthesized (TiB+TiC)/Ti Composites Prepared by Hot-pressing

    Institute of Scientific and Technical Information of China (English)

    Zhenzhu ZHENG; Lin GENG; Honglin WANG; Weimin ZHOU; Hongyu XU

    2003-01-01

    In-situ 5 vol.pct TiB whiskers and TiC particulates reinforced Ti composites were fabricated by blending Ti powderand B4C particulates followed by reactive hot-pressing. The microstructure of the composites was investigated byusing differential scanning c

  1. SEM in situ laboratory investigations on damage growth in GFRP composite under three-point bending tests

    DEFF Research Database (Denmark)

    Zhou, Hong Wei; Mishnaevsky, Leon; Brøndsted, Povl

    2010-01-01

    Glass fiber-reinforced polymer (GFRP) composites are widely used in low-weight constructions. SEM (scanning electron microscopy) in situ experiments of damage growth in GFRP composite under three-point bending loads are carried out. By summarizing the experimental results of three groups of samples...

  2. Microstructure development of in situ porous TiO/Cu composites

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Q.D., E-mail: 58124812@qq.com [Department of Materials & Metallurgy Engineering, Guizhou Institute of Technology, No.1 Caiguan Road, Guiyang 550003 (China); 2011 Special Functional Materials Collaborative Innovation Center of Guizhou Province, No.1 Caiguan Road, Guiyang 550003 (China); Huang, B.W. [Department of Materials & Metallurgy Engineering, Guizhou Institute of Technology, No.1 Caiguan Road, Guiyang 550003 (China); 2011 Special Functional Materials Collaborative Innovation Center of Guizhou Province, No.1 Caiguan Road, Guiyang 550003 (China); Li, W. [Department of Materials Engineering, Zhengzhou Technology College, No. 81 Zhengshang Road, Zhengzhou, 450051 (China); Shao, F. [2011 Special Functional Materials Collaborative Innovation Center of Guizhou Province, No.1 Caiguan Road, Guiyang 550003 (China)

    2016-07-05

    An in situ porous TiO/Cu composite is successfully prepared using powder metallurgy by the reaction of Ti{sub 2}CO and Cu powder. Ti{sub 2}CO powder is produced by the carbothermic reduction of titanium dioxide (TiO{sub 2}) at 1000 °C. Morphological examination of the composite shows that the porosity of composites lies in the range between 10.2% and 35.2%. As the volume fraction of TiO increases, the size of TiO becomes more fine. Scanning electron microscopy (SEM) of the fracture morphology indicates that TiO particles and the Cu matrix are connected by a Cu–Ti phase. - Highlights: • An porous TiO/Cu composite is successfully prepared by powder metallurgy technology. • The porosity of composites lies in the range between 10.2% and 35.2%. • The TiO particles and the Cu matrix are connected by a Cu-Ti phase.

  3. Self-Sensing Composites: In-Situ Detection of Fibre Fracture

    Directory of Open Access Journals (Sweden)

    Shoaib A. Malik

    2016-04-01

    Full Text Available The primary load-bearing component in a composite material is the reinforcing fibres. This paper reports on a technique to study the fracture of individual reinforcing fibres or filaments in real-time. Custom-made small-diameter optical fibres with a diameter of 12 (±2 micrometres were used to detect the fracture of individual filaments during tensile loading of unreinforced bundles and composites. The unimpregnated bundles were end-tabbed and tensile tested to failure. A simple technique based on resin-infusion was developed to manufacture composites with a negligible void content. In both cases, optical fibre connectors were attached to the ends of the small-diameter optical fibre bundles to enable light to be coupled into the bundle via one end whilst the opposite end was photographed using a high-speed camera. The feasibility of detecting the fracture of each of the filaments in the bundle and composite was demonstrated. The in-situ damage detection technique was also applied to E-glass bundles and composites; this will be reported in a subsequent publication.

  4. Fabrication of SiCp/Al Alloy Composites by In-situ Vacuum Hot Press Process

    Energy Technology Data Exchange (ETDEWEB)

    Choi, S. W.; Hong, S. K.; Kim, Y. M.; Kang, C. S. [Chonnam National University, Kwangju (Korea); Chang, S. Y. [Hanyang University, Seoul (Korea)

    2001-07-01

    SiCp/pure Al and SiCp/2024Al MMCs were fabricated by in-situ VHP process designed specially just in this study which is composed of the vacuum hot press at range from R.T. to 500 deg.C and the continuous extrusion without canning process at 520 deg.C. It was investigated the effect of SiC particle size, volume fraction and extrusion ratio on the tensile properties and micro structure in all composites. In case of the 10:1 extrusion ratio, but SiCp/pure Al and SiCp/2024Al composites were shown a sound appearance and a good micro structure without crack of SiCp as well as uniform distribution of SiCp. However, in case of the 16:1 extrusion ratio, the number of cracked SiC particles more than increased in a higher volume fraction composite and 2024Al matrix composite compared with pure Al matrix one. The tensile strength of the composites reinforced smaller SiCp was higher than that of the bigger SiCp reinforced in same volume fraction and extrusion ratio. (author) 14 refs., 14 figs.

  5. Mechanical Properties and Tribological Behavior of In Situ NbC/Fe Surface Composites

    Science.gov (United States)

    Cai, Xiaolong; Zhong, Lisheng; Xu, Yunhua

    2017-01-01

    The mechanical properties and tribological behavior of the niobium carbide (NbC)-reinforced gray cast iron surface composites prepared by in situ synthesis have been investigated. Composites are comprised of a thin compound layer and followed by a deep diffusion zone on the surface of gray cast iron. The graded distributions of the hardness and elastic modulus along the depth direction of the cross section of composites form in the ranges of 6.5-20.1 and 159.3-411.2 GPa, respectively. Meanwhile, dry wear tests for composites were implemented on pin-on-disk equipment at sliding speed of 14.7 × 10-2 m/s and under 5 or 20 N, respectively. The result indicates that tribological performances of composites are considerably dependent on the volume fraction and the grain size of the NbC as well as the mechanical properties of the matrices in different areas. The surface compound layer presents the lowest coefficient of friction and wear rate, and exhibits the highest wear resistance, in comparison with diffusion zone and substrate. Furthermore, the worn morphologies observed reveal the dominant wear mechanism is abrasive wear feature in compound layer and diffusion zone.

  6. Microstructure development of in situ porous TiO/Cu composites

    International Nuclear Information System (INIS)

    Qin, Q.D.; Huang, B.W.; Li, W.; Shao, F.

    2016-01-01

    An in situ porous TiO/Cu composite is successfully prepared using powder metallurgy by the reaction of Ti_2CO and Cu powder. Ti_2CO powder is produced by the carbothermic reduction of titanium dioxide (TiO_2) at 1000 °C. Morphological examination of the composite shows that the porosity of composites lies in the range between 10.2% and 35.2%. As the volume fraction of TiO increases, the size of TiO becomes more fine. Scanning electron microscopy (SEM) of the fracture morphology indicates that TiO particles and the Cu matrix are connected by a Cu–Ti phase. - Highlights: • An porous TiO/Cu composite is successfully prepared by powder metallurgy technology. • The porosity of composites lies in the range between 10.2% and 35.2%. • The TiO particles and the Cu matrix are connected by a Cu-Ti phase.

  7. Ohmic contact junction of carbon nanotubes fabricated by in situ electron beam deposition

    International Nuclear Information System (INIS)

    Wang, Y G; Wang, T H; Lin, X W; Dravid, V P

    2006-01-01

    We present experimental evidence of in situ fabrication of multi-walled carbon nanotube junctions via electron beam induced deposition. The tip-to-tip interconnection of the nanotubes involves the alignment of two nanotubes via a piezodriven nanomanipulator and nano-welding by electron beam deposition. Hydrocarbon contamination from the pump oil vapour of the vacuum system of the TEM chamber was used as the solder; this is superior to the already available metallic solders because its composition is identical to the carbon nanotube. The hydrocarbon deposition, with perfect wettability, on the nanotubes establishes strong mechanical binding between the two nanotubes to form an integrated structure. Consequently, the nanotubes cross-linked by the hydrocarbon solder produce good electrical and mechanical connections. The joint dimension was determined by the size of the electron beam, which results in a sound junction with well-defined geometry and the smallest junction size obtained so far. In situ electric measurement showed a linear current-voltage property for the multi-walled nanotube junction

  8. In-situ synthesis of magnetic iron-oxide nanoparticle-nanofibre composites using electrospinning

    International Nuclear Information System (INIS)

    Burke, Luke; Mortimer, Chris J.; Curtis, Daniel J.; Lewis, Aled R.; Williams, Rhodri; Hawkins, Karl; Maffeis, Thierry G.G.; Wright, Chris J.

    2017-01-01

    We demonstrate a facile, one-step process to form polymer scaffolds composed of magnetic iron oxide nanoparticles (MNPs) contained within electrospun nano- and micro-fibres of two biocompatible polymers, Poly(ethylene oxide) (PEO) and Poly(vinyl pyrrolidone) (PVP). This was achieved with both needle and free-surface electrospinning systems demonstrating the scalability of the composite fibre manufacture; a 228 fold increase in fibre fabrication was observed for the free-surface system. In all cases the nanoparticle-nanofibre composite scaffolds displayed morphological properties as good as or better than those previously described and fabricated using complex multi-stage techniques. Fibres produced had an average diameter (Needle-spun: 125 ± 18 nm (PEO) and 1.58 ± 0.28 μm (PVP); Free-surface electrospun: 155 ± 31 nm (PEO)) similar to that reported previously, were smooth with no bead defects. Nanoparticle-nanofibre composites were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) (Nanoparticle average diameter ranging from 8 ± 3 nm to 27 ± 5 nm), XRD (Phase of iron oxide nanoparticles identified as magnetite) and nuclear magnetic resonance relaxation measurements (NMR) (T1/T2: 32.44 for PEO fibres containing MNPs) were used to verify the magnetic behaviour of MNPs. This study represents a significant step forward for production rates of magnetic nanoparticle-nanofibre composite scaffolds by the electrospinning technique. - Graphical abstract: We present a novel facile, one-step process for the in-situ synthesis of magnetic iron oxide nanoparticle-nanofibre composites using both needle and free-surface electrospinning. This is a significant step forward for production rates of magnetic nanoparticle-nanofibre scaffolds both in terms of fibre and nanoparticle production. - Highlights: • We present a novel process for the in-situ synthesis of magnetic iron oxide nanoparticle

  9. In-situ synthesis of magnetic iron-oxide nanoparticle-nanofibre composites using electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Burke, Luke; Mortimer, Chris J. [Biomaterials, Biofouling and Biofilms Engineering Laboratory (B3EL), Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Curtis, Daniel J.; Lewis, Aled R.; Williams, Rhodri [Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Hawkins, Karl [Centre for NanoHealth (CNH), Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Maffeis, Thierry G.G. [Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Wright, Chris J., E-mail: c.wright@swansea.ac.uk [Biomaterials, Biofouling and Biofilms Engineering Laboratory (B3EL), Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Centre for NanoHealth (CNH), Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom)

    2017-01-01

    We demonstrate a facile, one-step process to form polymer scaffolds composed of magnetic iron oxide nanoparticles (MNPs) contained within electrospun nano- and micro-fibres of two biocompatible polymers, Poly(ethylene oxide) (PEO) and Poly(vinyl pyrrolidone) (PVP). This was achieved with both needle and free-surface electrospinning systems demonstrating the scalability of the composite fibre manufacture; a 228 fold increase in fibre fabrication was observed for the free-surface system. In all cases the nanoparticle-nanofibre composite scaffolds displayed morphological properties as good as or better than those previously described and fabricated using complex multi-stage techniques. Fibres produced had an average diameter (Needle-spun: 125 ± 18 nm (PEO) and 1.58 ± 0.28 μm (PVP); Free-surface electrospun: 155 ± 31 nm (PEO)) similar to that reported previously, were smooth with no bead defects. Nanoparticle-nanofibre composites were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) (Nanoparticle average diameter ranging from 8 ± 3 nm to 27 ± 5 nm), XRD (Phase of iron oxide nanoparticles identified as magnetite) and nuclear magnetic resonance relaxation measurements (NMR) (T1/T2: 32.44 for PEO fibres containing MNPs) were used to verify the magnetic behaviour of MNPs. This study represents a significant step forward for production rates of magnetic nanoparticle-nanofibre composite scaffolds by the electrospinning technique. - Graphical abstract: We present a novel facile, one-step process for the in-situ synthesis of magnetic iron oxide nanoparticle-nanofibre composites using both needle and free-surface electrospinning. This is a significant step forward for production rates of magnetic nanoparticle-nanofibre scaffolds both in terms of fibre and nanoparticle production. - Highlights: • We present a novel process for the in-situ synthesis of magnetic iron oxide nanoparticle

  10. CHEMICAL COMPOSITION AND IN SITU EVALUATION OF FRESH AND ENSILED SUGARCANE (Saccharum officinarum

    Directory of Open Access Journals (Sweden)

    José Andrés Reyes Gutiérrez

    2015-12-01

    Full Text Available This study evaluated chemical composition and in situ degradability of dry matter (DM, organic matter (OM and ruminal pH of fresh (FSC and ensiled (SCS sugarcane (Saccharum officinarum forage diets. In situ digestibility was determined using the nylon bag technique with four cows fitted with a rumen cannula. Cows were fed with fresh or ensiled sugar cane and supplemented with 1 kg of commercial dairy concentrate (18% CP. Ground sample (5g for each sugar cane (FSC, and SCS were incubated in rumen for 0, 8, 12, 24, 36, 48, 72 and 96 h. Treatments were distributed in a completely randomized design with six replicates. ESC showed significant changes (P0.05 was noted. In situ digestibility of organic matter (ISDOM, % was higher (P0.05 at 12 and 76 h of incubation. The ruminal pH showed no differences (P>0.05 between treatments. It is concluded that the silage of sugar cane is an alternative to provide forage in the season of low growth and quality of the grass. Â

  11. A Novel FCC Catalyst Based on a Porous Composite Material Synthesized via an In Situ Technique

    Directory of Open Access Journals (Sweden)

    Shu-Qin Zheng

    2015-11-01

    Full Text Available To overcome diffusion limitations and improve transport in microporous zeolite, the materials with a wide-pore structure have been developed. In this paper, composite microspheres with hierarchical porous structure were synthesized by an in situ technique using sepiolite, kaolin and pseudoboehmite as raw material. A novel fluid catalytic cracking (FCC catalyst for maximizing light oil yield was prepared based on the composite materials. The catalyst was characterized by XRD, FT-IR, SEM, nitrogen adsorption-desorption techniques and tested in a bench FCC unit. The results indicated that the catalyst had more meso- and macropores and more acid sites than the reference catalyst, and thus can increase light oil yield by 1.31 %, while exhibiting better gasoline and coke selectivity.

  12. Conductive nano composites based on cellulose nano fiber coated poly aniline via in situ polymerization

    International Nuclear Information System (INIS)

    Silva, Michael J. da; Sanches, Alex O.; Malmonge, Luiz F.; Malmonge, Jose A.; Medeiros, Eliton S. de; Rosa, Morsyleide F.

    2011-01-01

    Cellulose nano fiber (CNF) was extracted by acid hydrolysis from cotton microfibril and nano composites of CNF/PANI-DBSA were obtained by in situ polymerization of aniline onto CNF. The ratios between DBSA/aniline and aniline/oxidant were varied and the nano composites were characterized by four probes direct current (dc) electrical conductivity, ultraviolet-visible (UV-Vis-NIR) and FTIR spectroscopy and X-ray diffraction (XRD). Electrical conductive about ∼10 -1 S/cm was research and was independent of DBSA/aniline molar ratio between 2-4 and the aniline/oxidant molar ratio between 1-5. X-ray patterns of the samples show crystalline peaks characteristic of cellulose I. The FTIR spectra confirmed the presence of PANI and CNF in all samples. (author)

  13. Laser soldering of Sn-Ag-Cu and Sn-Zn-Bi lead-free solder pastes

    Science.gov (United States)

    Takahashi, Junichi; Nakahara, Sumio; Hisada, Shigeyoshi; Fujita, Takeyoshi

    2004-10-01

    It has reported that a waste of an electronics substrate including lead and its compound such as 63Sn-37Pb has polluted the environment with acid rain. For that environment problem the development of lead-free solder alloys has been promoted in order to find out the substitute for Sn-Pb solders in the United States, Europe, and Japan. In a present electronics industry, typical alloys have narrowed down to Sn-Ag-Cu and Sn-Zn lead-free solder. In this study, solderability of Pb-free solder that are Sn-Ag-Cu and Sn-Zn-Bi alloy was studied on soldering using YAG (yttrium aluminum garnet) laser and diode laser. Experiments were peformed in order to determine the range of soldering parameters for obtaining an appropriate wettability based on a visual inspection. Joining strength of surface mounting chip components soldered on PCB (printed circuit board) was tested on application thickness of solder paste (0.2, 0.3, and 0.4 mm). In addition, joining strength characteristics of eutectic Sn-Pb alloy and under different power density were examined. As a result, solderability of Sn-Ag-Cu (Pb-free) solder paste are equivalent to that of coventional Sn-Pb solder paste, and are superior to that of Sn-Zn-Bi solder paste in the laser soldering method.

  14. Solvent exfoliated graphene for reinforcement of PMMA composites prepared by in situ polymerization

    International Nuclear Information System (INIS)

    Wang, Jialiang; Shi, Zixing; Ge, Yu; Wang, Yan; Fan, Jinchen; Yin, Jie

    2012-01-01

    Graphene (GP)-based polymer nanocomposites have attracted considerable scientific attention due to its pronounced improvement in mechanical, thermal and electrical properties compared with pure polymers. However, the preparation of well-dispersed and high-quality GP reinforced polymer composites remains a challenge. In this paper, a simple and facile approach for preparation of poly(methyl methacrylate) (PMMA) functionalized GP (GPMMA) via in situ free radical polymerization is reported. Fourier transform infrared (FTIR), X-ray photoelectron spectra (XPS), Raman, transmission electron microscope (TEM) and thermogravimetric analysis (TGA) are used to confirm the successful grafting of PMMA chains onto the GP sheets. Composite films are prepared by incorporating different amounts of GPMMA into the PMMA matrix through solution-casting method. Compared with pure PMMA, PMMA/GPMMA composites show simultaneously improved Young's modulus, tensile stress, elongation at break and thermal stability by addition of only 0.5 wt% GPMMA. The excellent reinforcement is attributed to good dispersion of high-quality GPMMA and strong interfacial adhesion between GPMMA and PMMA matrix as evidenced by scanning electron microscope (SEM) images of the fracture surfaces. Consequently, this simple protocol has great potential in the preparation of various high-performance polymer composites. Highlights: ► Functionalization of solvent exfoliated graphene by in situ polymerization. ► A simple and scalable method for preparing high-quality graphene. ► Functionalized graphene can be well-dispersed and have a strong interfacial adhesion with the polymer matrix. ► The nanocomposites exhibit a remarkable improvement of thermal and mechanical properties.

  15. Laser processing of in situ TiN/Ti composite coating on titanium.

    Science.gov (United States)

    Sahasrabudhe, Himanshu; Soderlind, Julie; Bandyopadhyay, Amit

    2016-01-01

    Laser remelting of commercially pure titanium (CP-Ti) surface was done in a nitrogen rich inert atmosphere to form in situ TiN/Ti composite coating. Laser surface remelting was performed at two different laser powers of 425 W and 475 W. At each power, samples were fabricated with one or two laser scans. The resultant material was a nitride rich in situ coating that was created on the surface. The cross sections revealed a graded microstructure. There was presence of nitride rich dendrites dispersed in α-Ti matrix at the uppermost region. The structure gradually changed with lesser dendrites and more heat affected α-Ti phase maintaining a smooth interface. With increasing laser power, the dendrites appeared to be larger in size. Samples with two laser scans showed discontinuous dendrites and more α-Ti phase as compared to the samples with one laser scan. The resultant composite of TiN along with Ti2N in α-Ti showed substantially higher hardness and wear resistance than the untreated CP-Ti substrate. Coefficient of friction was also found to reduce due to surface nitridation. Leaching of Ti(4+) ions during wear test in DI water medium was found to reduce due to laser surface nitriding. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Thermomechanical fatigue life prediction for several solders

    Science.gov (United States)

    Wen, Shengmin

    Since solder connections operate at high homologous temperature, solders are high temperature materials. This feature makes their mechanical behavior and fatigue phenomena unique. Based on experimental findings, a physical damage mechanism is introduced for solders. The mechanism views the damage process as a series of independent local damage events characterized by the failure of individual grains, while the structural damage is the eventual percolation result of such local events. Fine's dislocation energy density concept and Mura's microcrack initiation theory are adopted to derive the fatigue formula for an individual grain. A physical damage metric is introduced to describe the material with damage. A unified creep and plasticity constitutive model is adopted to simulate the mechanical behavior of solders. The model is cast into a continuum damage mechanics framework to simulate material with damage. The model gives good agreement with the experimental results of 96.5Pb-3.5Sn and 96.5Sn-3.5Ag solders under uniaxial strain-controlled cyclic loading. The model is convenient for implementation into commercial computational packages. Also presented is a fatigue theory with its failure criterion for solders based on physical damage mechanism. By introducing grain orientation into the fatigue formula, an m-N curve (m is Schmid factor) at constant loading condition is suggested for fatigue of grains with different orientations. A solder structure is defined as fatigued when the damage metric reaches a critical threshold, since at this threshold the failed grains may form a cluster and percolate through the structure according to percolation theory. Fatigue data of 96.5Pb-3.5Sn solder bulk specimens under various uniaxial tension tests were analyzed. Results show that the theory gives consistent predictions under broad conditions, while inelastic strain theory does not. The theory is anisotropic with no size limitation to its application, which could be suitable for

  17. In-situ reduced graphene oxide-polyvinyl alcohol composite coatings as protective layers on magnesium substrates

    Directory of Open Access Journals (Sweden)

    Xingkai Zhang

    2017-06-01

    Full Text Available A simple and feasible method was developed to fabricate in-situ reduced graphene oxide-polyvinyl alcohol composite (GO-PVA coatings as protective layers on magnesium substrates. Polyvinyl alcohol was used as an in-situ reductant to transform GO into reduced GO. Contiguous and uniform GO-PVA coatings were prepared on magnesium substrates by dip-coating method, and were further thermally treated at 120 °C under ambient condition to obtain in-situ reduced GO-PVA coatings. Owing to the reducing effect of PVA, thermal treatment at low temperature led to effective in-situ reduction of GO as confirmed by XRD, Raman, FTIR and XPS tests. The corrosion current density of magnesium substrates in 3.5 wt% NaCl solution could be lowered to its 1/25 when using in-situ reduced GO-PVA coatings as protective layers.

  18. In situ fabrication and characterization of cobalt ferrite nanorods/graphene composites

    International Nuclear Information System (INIS)

    Fu, Min; Jiao, Qingze; Zhao, Yun

    2013-01-01

    Cobalt ferrite nanorods/graphene composites were prepared by a one-step hydrothermal process using NaHSO 3 as the reducing agent and 1-propyl-3-hexadecylimidazolium bromide as the structure growth-directing template. The reduction of graphene oxide and the in situ formation of cobalt ferrite nanorods were accomplished in a one-step reaction. The structure and morphology of as-obtained composites were characterized by field emission scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, atomic force microscope, X-ray diffractometer, Fourier transform infrared spectra, X-ray photoelectron spectroscopy and Raman spectroscopy. Uniform rod-like cobalt ferrites with diameters of about 100 nm and length of about 800 nm were homogeneously distributed on the graphene sheets. The hybrid materials showed a saturation magnetization of 42.5 emu/g and coercivity of 495.1 Oe at room temperature. The electromagnetic parameters were measured using a vector network analyzer. A minimum reflection loss (RL) of − 25.8 dB was observed at 16.1 GHz for the cobalt ferrite nanorods/graphene composites with a thickness of 2 mm, and the effective absorption frequency (RL < − 10 dB) ranged from 13.5 to 18.0 GHz. The composites exhibited better absorbing properties than the cobalt ferrite nanorods and the mixture of cobalt ferrite nanorods and graphene. - Highlights: • Reduction of GO and formation of ferrites were accomplished in a one-step reaction. • Ionic liquid was used to control 1D growth of ferrite nanorods for the first time. • Cobalt ferrite nanorods/graphene composites showed dielectric and magnetic loss. • Cobalt ferrite nanorods/graphene composites exhibited better absorbing properties

  19. In situ composition measurements of Bunsen reaction solution by radiation probes

    Energy Technology Data Exchange (ETDEWEB)

    Kubo, Shinji; Nagaya, Yasunobu [Japan Atomic Energy Agency (Japan)

    2010-07-01

    Measuring equipments are integral to chemical process controls. A stable hydrogen production by the Iodine-Sulfur thermochemical water-splitting process is relatively difficult because of lack of existing in situ composition measurement techniques for multiple components and corrosive solution. Composition regulations of Bunsen reaction solution is particularly important, since a closed cycle system provided with this process causes that the many streams with different composition return to this section. Accordingly Bunsen solution becomes changeable composition. Radiation probes have a potential for applications to determine this multiple component solution while the non-contact approach avoids the corrosive issues. Moreover the probes have features of the promptness, contact-less and sequential use. Laboratory scale experiments to evaluate these possibilities of the measurement were conducted with use of simulated Bunsen solution, HIx solution and H{sub 2}SO{sub 4} solution, containing HI, I2, H{sub 2}SO{sub 4} and H{sub 2}O and sealed radiation sources. Radiations were counted, which were interacted with the solutions in various compositions around room temperature contained in vessels. For HIx solution, the obtained counting rates were correlated with hydrogen volume concentrations; moreover, the application of the Monte Carlo method suggests possibilities that the detector responses for HIx solution by the radiation probes are predictable. For H{sub 2}SO{sub 4} solution, iodine atoms had significant influences on the relationship between output values of two gamma-ray density meters, cesium source as higher energy and barium source as lower energy. This results suggest that the neutron ray probe, the gamma-ray probes of both lower energy and higher energy have possibilities to determine the composition of Bunsen solution of HIx and H{sub 2}SO{sub 4} solutions. (orig.)

  20. VICI (Venus In Situ Composition Investigations): The Next Step in Understanding Venus Climate Evolution

    Science.gov (United States)

    Glaze, L. S.; Garvin, J. B.

    2017-12-01

    Venus provides a natural laboratory to explore an example of terrestrial planet evolution that may be cosmically ubiquitous. By better understanding the composition of the Venus atmosphere and surface, we can better constrain the efficiency of the Venusian greenhouse. VICI is a proposed NASA New Frontiers mission that delivers two landers to Venus on two separate Venus fly-bys. Following six orbital remote sensing missions to Venus (since 1978), VICI would be the first mission to land on the Venus surface since 1985, and the first U.S. mission to enter the Venus atmosphere in 49 years. The four major VICI science objectives are: Atmospheric origin and evolution: Understand the origin of the Venus atmosphere, how it has evolved, including how recently Venus lost its oceans, and how and why it is different from the atmospheres of Earth and Mars, through in situ measurements of key noble gases, nitrogen, and hydrogen. Atmospheric composition and structure: Reveal the unknown chemical processes and structure in Venus' deepest atmosphere that dominate the current climate through two comprehensive, in situ vertical profiles. Surface properties and geologic evolution: For the first time ever, explore the tessera from the surface, specifically to test hypotheses of ancient content-building cycles, erosion, and links to past climates using multi-point mineralogy, elemental chemistry, imaging and topography. Surface-atmosphere interactions: Characterize Venus' surface weathering environment and provide insight into the sulfur cycle at the surface-atmosphere interface by integrating rich atmospheric composition and structure datasets with imaging, surface mineralogy, and elemental rock composition. VICI is designed to study Venus' climate history through detailed atmospheric composition measurements not possible on earlier missions. In addition, VICI images the tessera surface during descent enabling detailed topography to be generated. Finally, VICI makes multiple elemental

  1. Preparation and properties of in situ amino-functionalized graphene oxide/polyimide composite films

    Science.gov (United States)

    Lu, Yunhua; Hao, Jican; Xiao, Guoyong; Chen, Lin; Wang, Tonghua; Hu, Zhizhi

    2017-11-01

    The pure light-colored and transparent polyimide (PI) film was prepared from aromatic dianhydride 4,4‧-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and diamine 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) in the solvent of DMAc via two-step method. Graphene oxide (GO) was in situ grafted with 6FAPB and directly used as a functional inorganic nanofiller to further synthesize poly(amic acid) (PAA)/GO solution. Then, PI/GO composite films with different loadings of GO were prepared by the thermal imidization. The mechanical, thermal, optical, electrical, surface properties, and electrochemical behavior were characterized. The FTIR and XPS results indicate that amino groups can be successfully grafted on the surface of GO. The tensile strength and Young's modulus of the PI-1.0%GO composite film were increased to 118.4 MPa and 2.91 GPa, respectively, which was an approximate improvement of 30.8% and 39.9% compared with pure PI film. These PI/GO composites showed around 256 °C for the glass transition temperature, and around 535 °C for the 5% thermal decomposition temperature, respectively. However, the optical transmittance was significantly decreased from 81.5% (pure PI) to 0.8% (PI-1.0%GO). Besides, the electrical conductivity increased from 1.6 × 10-13 S/m (pure PI) to 2.5 × 10-9 S/m (PI-1.0%GO). Furthermore, when the incorporation of GO was 1.0 wt%, an obvious reduction from 1.08% (pure PI) to 0.65% in the water uptake was observed for the PI/GO composite films, and the water surface contact angle raised from 72.5° (pure PI) to 83.5°. The electrochemical behavior showed that the ability of oxygen atom on the imide ring to gain and loss electron was increased due to incorporation of GO. These results indicated that the strong interfacial interaction between GO and PAA as well as uniform dispersion of GO in PI matrix were benefit to improve the mechanical, thermal, electrical properties and so on. The in situ amino-functionalized approach

  2. Reduction Dynamics of Doped Ceria, Nickel Oxide, and Cermet Composites Probed Using In Situ Raman Spectroscopy.

    Science.gov (United States)

    Maher, Robert C; Shearing, Paul R; Brightman, Edward; Brett, Dan J L; Brandon, Nigel P; Cohen, Lesley F

    2016-01-01

    The redox properties of gadolinium doped ceria (CGO) and nickel oxide (NiO) composite cermets underpin the operation of solid oxide electrochemical cells. Although these systems have been widely studied, a full comprehension of the reaction dynamics at the interface of these materials is lacking. Here, in situ Raman spectroscopic monitoring of the redox cycle is used to investigate the interplay between the dynamic and competing processes of hydrogen spillover and water dissociation on the doped ceria surface. In order to elucidate these mechanisms, the redox process in pure CGO and NiO is studied when exposed to wet and dry hydrogen and is compared to the cermet behavior. In dry hydrogen, CGO reduces relatively rapidly via a series of intermediate phases, while NiO reduces via a single-step process. In wet reducing atmospheres, however, the oxidation state of pure CGO is initially stabilized due to the dissociation of water by reduced Ce(III) and subsequent incorporation of oxygen into the structure. In the reduction process involving the composite cermet, the close proximity of the NiO improves the efficiency and speed of the composite reduction process. Although NiO is already incorporated into working cells, these observations suggest direct routes to further improve cell performance.

  3. Polyurethane/organo clay nano composite materials via in-situ polymerization

    International Nuclear Information System (INIS)

    Rehab, A.; Agag, T; Akelah, A.; Shalaby, N.

    2005-01-01

    Polyurethane/organo clay nano composites have been synthesized via in situ polymerization. The organo clay firstly prepared by intercalation of lyamine or amino lauric acid into montmorillonite-clay (MMT) through ion exchange process. The syntheses of polyurethane/organo clay hybrid films containing different ratio of clay were carried out by swelling the organo clay, into diol and diamine or into different kinds of diols, followed by addition of diisocyanate. The nano composites with dispersed structure of MMT was obtained as evidence by scanning electron microscope and x-ray diffraction. X-ray analysis showed that the d-spacing increased to more than 44A since there is no peaks corresponding to do spacing in organo clay with all the ratios (1, 5, 10, 20%). Also, SEM results confirm the dispersion of nanometer silicate layers in the polyurethane matrix. This indicated that the clay was completely exfoliated and homogeneous dispersion in the polyurethane matrix. Also, it was found that the presence of organo clay leads to improvement the mechanical properties. Since, the tensile strength increased with increasing the organo clay contents to 20% by the ratio 194% in compared to the 1H: with 0% organo clay. Also, the elongation is a decreases with increasing the organo clay contents. The results shown the tensile strength of PU/SMA/ALA-MMT nano composites is high by 6-7 times than the corresponding to PU/Tvr-MMT

  4. High temperature soldering of graphite

    International Nuclear Information System (INIS)

    Anikin, L.T.; Kravetskij, G.A.; Dergunova, V.S.

    1977-01-01

    The effect is studied of the brazing temperature on the strength of the brazed joint of graphite materials. In one case, iron and nickel are used as solder, and in another, molybdenum. The contact heating of the iron and nickel with the graphite has been studied in the temperature range of 1400-2400 ged C, and molybdenum, 2200-2600 deg C. The quality of the joints has been judged by the tensile strength at temperatures of 2500-2800 deg C and by the microstructure. An investigation into the kinetics of carbon dissolution in molten iron has shown that the failure of the graphite in contact with the iron melt is due to the incorporation of iron atoms in the interbase planes. The strength of a joint formed with the participation of the vapour-gas phase is 2.5 times higher than that of a joint obtained by graphite recrystallization through the carbon-containing metal melt. The critical temperatures are determined of graphite brazing with nickel, iron, and molybdenum interlayers, which sharply increase the strength of the brazed joint as a result of the formation of a vapour-gas phase and deposition of fine-crystal carbon

  5. In situ reactive compatibilization of natural rubber/acrylic-bentonite composites via peroxide-induced vulcanization

    International Nuclear Information System (INIS)

    Fu, Lihua; Lei, Zhiwen; Xu, Chuanhui; Chen, Yukun

    2016-01-01

    To achieve good interfacial interaction between fillers and rubber matrix is always a hot topic in rubber reinforcing industry. In this paper, acid activated bentonite (Bt) was alkalified to be alkaline calcium-bentonite (ACBt), then acrylic acid (AA) was employed to modify ACBt to obtain acrylic-bentonite (ABt). The results of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) illustrated that acrylate groups were chemically boned onto the surface of Bt and the layer spacing of Bt was increased. During peroxide-induced vulcanization, in situ compatibilization of ABt was realized via the reaction between the unsaturated bonds of acrylate groups on the surface of Bt and the natural rubber (NR) chains. This resulted in an enhanced cross-linked network which contributed to the improved mechanical properties of NR/ABt composites. - Highlights: • Acrylate groups were chemically boned onto the surface of bentonite. • In situ compatibilization was realized via the reaction of acrylate group and NR. • ABt particles participated in forming the NR crosslink network. • A potential reinforcing material options for “white” rubber products.

  6. In situ reactive compatibilization of natural rubber/acrylic-bentonite composites via peroxide-induced vulcanization

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Lihua; Lei, Zhiwen [Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Xu, Chuanhui, E-mail: xuhuiyee@gxu.edu.cn [Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology, School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Chen, Yukun, E-mail: cyk@scut.edu.cn [The Key Laboratory of Polymer Processing Engineering, Ministry of Education, China(South China University of Technology), Guangzhou, 510640 (China)

    2016-02-15

    To achieve good interfacial interaction between fillers and rubber matrix is always a hot topic in rubber reinforcing industry. In this paper, acid activated bentonite (Bt) was alkalified to be alkaline calcium-bentonite (ACBt), then acrylic acid (AA) was employed to modify ACBt to obtain acrylic-bentonite (ABt). The results of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) illustrated that acrylate groups were chemically boned onto the surface of Bt and the layer spacing of Bt was increased. During peroxide-induced vulcanization, in situ compatibilization of ABt was realized via the reaction between the unsaturated bonds of acrylate groups on the surface of Bt and the natural rubber (NR) chains. This resulted in an enhanced cross-linked network which contributed to the improved mechanical properties of NR/ABt composites. - Highlights: • Acrylate groups were chemically boned onto the surface of bentonite. • In situ compatibilization was realized via the reaction of acrylate group and NR. • ABt particles participated in forming the NR crosslink network. • A potential reinforcing material options for “white” rubber products.

  7. Microstructure evolution and thermomechanical fatigue of solder materials

    NARCIS (Netherlands)

    Matin, M.A.

    2005-01-01

    The microelectronics industry is confronted with the new challenge to produce joints with lead-free solder materials replacing classical tin-lead solders in devices used in many fields (e.g. consumer electronics, road transport, aviation, space-crafts, telecommunication). In service, solder

  8. Efforts to Develop a 300°C Solder

    Energy Technology Data Exchange (ETDEWEB)

    Norann, Randy A [Perma Works LLC

    2015-01-25

    This paper covers the efforts made to find a 300°C electrical solder solution for geothermal well monitoring and logging tools by Perma Works LLC. This paper covers: why a high temperature solder is needed, what makes for a good solder, testing flux, testing conductive epoxy and testing intermetallic bonds. Future areas of research are suggested.

  9. Preparation of poly (methyl methacrylate)/nanometer calcium carbonate composite by in-situ emulsion polymerization

    Institute of Scientific and Technical Information of China (English)

    史建明; 包永忠; 黄志明; 翁志学

    2004-01-01

    Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate (nano-CaCO3) surface modified with (-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.

  10. A novel method for direct solder bump pull testing using lead-free solders

    Science.gov (United States)

    Turner, Gregory Alan

    This thesis focuses on the design, fabrication, and evaluation of a new method for testing the adhesion strength of lead-free solders, named the Isotraction Bump Pull method (IBP). In order to develop a direct solder joint-strength testing method that did not require customization for different solder types, bump sizes, specific equipment, or trial-and-error, a combination of two widely used and accepted standards was created. First, solder bumps were made from three types of lead free solder were generated on untreated copper PCB substrates using an in-house fabricated solder bump-on-demand generator, Following this, the newly developed method made use of a polymer epoxy to encapsulate the solder bumps that could then be tested under tension using a high precision universal vertical load machine. The tests produced repeatable and predictable results for each of the three alloys tested that were in agreement with the relative behavior of the same alloys using other testing methods in the literature. The median peak stress at failure for the three solders tested were 2020.52 psi, 940.57 psi, and 2781.0 psi, and were within one standard deviation of the of all data collected for each solder. The assumptions in this work that brittle fracture occurred through the Intermetallic Compound layer (IMC) were validated with the use of Energy-Dispersive X-Ray Spectrometry and high magnification of the fractured surface of both newly exposed sides of the test specimens. Following this, an examination of the process to apply the results from the tensile tests into standard material science equations for the fracture of the systems was performed..

  11. Development of high melting point, environmentally friendly solders, using the calphad approach

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2008-01-01

    An attempt has been made using the CALPHAD approach via Thermo-Calc to explore the various possible chemical compositions that adhere to the melting criterion i.e. 270-350 degrees C, required to replace the traditionally used high lead content solders for first level packaging applications. Vario...... tension have also been considered. Special focus has been given to toxicity related issues since the main ideology of looking for an alternative to high lead containing solders is not related to technical issues but due to environmental concerns.......An attempt has been made using the CALPHAD approach via Thermo-Calc to explore the various possible chemical compositions that adhere to the melting criterion i.e. 270-350 degrees C, required to replace the traditionally used high lead content solders for first level packaging applications. Various...... of promising solder alloy candidates. The ternary combinations that satisfied the primary solidification requirement were scrutinized taking into account the commercial interests i.e. availability, cost-effectiveness, recyclability and toxicity issues. Technical issues like manufacturability and surface...

  12. Microstructure and mechanical properties of Al/Fe-aluminide in-situ composite prepared by reactive stir casting route

    International Nuclear Information System (INIS)

    Chatterjee, Subhranshu; Sinha, Arijit; Das, Debdulal; Ghosh, Sumit; Basumallick, Amitava

    2013-01-01

    Iron aluminide particulate reinforced aluminium composites were prepared by a simple liquid metal stir casting route. The particulate intermetallic reinforcements were formed by in-situ reaction between molten aluminium and a rotating mild steel stirrer at 800 °C. X-ray diffraction studies were carried out to identify the types of iron aluminide particulates present in the as cast composite. Compositional variations of the composite samples were estimated with the aid of energy dispersive spectroscopy. The microstructural features of the composite were studied with respect to different heat treatment schedules and deformation conditions. Microhardness and nanoindentation measurements were also carried out to assess the micromechanical behaviour e.g., hardness and elastic modulus in micrometric length scale of the composite samples. Tensile tests and fractographic analysis were performed to estimate the mechanical properties and determine the mode of failure of the samples. The microstructure and mechanical properties of the composite samples were correlated and discussed

  13. A Hodge dual for soldered bundles

    International Nuclear Information System (INIS)

    Lucas, Tiago Gribl; Pereira, J G

    2009-01-01

    In order to account for all possible contractions allowed by the presence of the solder form, a generalized Hodge dual is defined for the case of soldered bundles. Although for curvature the generalized dual coincides with the usual one, for torsion it gives a completely new dual definition. Starting from the standard form of a gauge Lagrangian for the translation group, the generalized Hodge dual yields precisely the Lagrangian of the teleparallel equivalent of general relativity, and consequently also the Einstein-Hilbert Lagrangian of general relativity

  14. Visual detection of defects in solder joints

    Science.gov (United States)

    Blaignan, V. B.; Bourbakis, Nikolaos G.; Moghaddamzadeh, Ali; Yfantis, Evangelos A.

    1995-03-01

    The automatic, real-time visual acquisition and inspection of VLSI boards requires the use of machine vision and artificial intelligence methodologies in a new `frame' for the achievement of better results regarding efficiency, products quality and automated service. In this paper the visual detection and classification of different types of defects on solder joints in PC boards is presented by combining several image processing methods, such as smoothing, segmentation, edge detection, contour extraction and shape analysis. The results of this paper are based on simulated solder defects and a real one.

  15. Carbon nanotubes-porous ceramic composite by in situ CCVD growth of CNTs

    International Nuclear Information System (INIS)

    Mazumder, Sangram; Sarkar, Naboneeta; Park, Jung Gyu; Han, In Sub; Kim, Ik Jin

    2016-01-01

    A novel approach towards the formation of Carbon nanotubes-porous alumina ceramic composite was attempted by the application of three different reaction techniques. Porous alumina ceramics having micrometer pore dimensions were developed using the direct foaming technique. NaA zeolites were simultaneously synthesized and coated within the porous ceramics by an in situ hydrothermal process and were subjected to a simple ion exchange reaction for preparing the suitable catalyst material for Carbon nanotubes (CNTs) synthesis. The catalytic chemical vapour deposition (CCVD) technique was used to grow CNTs within the porous ceramics and the effect of growth time on the synthesized CNTs were investigated. Phase compositions of the samples were analysed by X-ray diffractometer (XRD). Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) were used for morphology, surface quality and structural analysis. Crystallinity, defects and yield were studied by Raman spectroscopy and thermogravimetric analysis (TGA). - Highlights: • Novel processing route of MWCNTs grown on Cobalt-zeolites-porous ceramics by CCVD. • CCVD time of 120 min produced MWCNTs with most prominent tube-like structure. • 120 min produced highest yield (19.46%) of CNTs with an I_D/I_G ratio of 0.88.

  16. a Study on Microstructure Characteristics of IN SITU Formed TiC Reinforced Composite Coatings

    Science.gov (United States)

    Liu, Peng; Guo, Wei; Luo, Hui

    2012-04-01

    In situ synthesized TiC reinforced composite coating was fabricated by laser cladding of Al-Ni-Cr-C powders on titanium alloys, which can greatly improve the surface performance of the substrate. In this study, the Al-Ni-Cr-C laser-cladded composite coatings have been researched by means of X-ray diffraction, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). There was a metallurgical combination between the Al-Ni-Cr-C laser-cladded coating and the Ti-6Al-4V substrate, and the micro-hardness of the Al-Ni-Cr-C laser-cladded coating was in the range of 1200-1450 HV0.2, which was 3-4 times higher than that of Ti-6Al-4V substrate. Furthermore, the reinforcement of theAl-Ni-Cr-C laser-cladded coating were mainly contributed to the action of the TiC, Ti3Al, Cr7C3, Al8Cr5 phases and the solution strengthening.

  17. Carbon nanotubes-porous ceramic composite by in situ CCVD growth of CNTs

    Energy Technology Data Exchange (ETDEWEB)

    Mazumder, Sangram; Sarkar, Naboneeta; Park, Jung Gyu [Institute of Processing and Application of Inorganic Materials (PAIM), Department of Materials Science and Engineering, Hanseo University, #360 Daegok-ri, Haemi-myeon, Seosan-si, Chungnam, 356-706 (Korea, Republic of); Han, In Sub [Korea Institute of Energy Research (KIER), #152 Gajeong-gu, Daejeon 305-343 (Korea, Republic of); Kim, Ik Jin, E-mail: ijkim@hanseo.ac.kr [Institute of Processing and Application of Inorganic Materials (PAIM), Department of Materials Science and Engineering, Hanseo University, #360 Daegok-ri, Haemi-myeon, Seosan-si, Chungnam, 356-706 (Korea, Republic of)

    2016-03-01

    A novel approach towards the formation of Carbon nanotubes-porous alumina ceramic composite was attempted by the application of three different reaction techniques. Porous alumina ceramics having micrometer pore dimensions were developed using the direct foaming technique. NaA zeolites were simultaneously synthesized and coated within the porous ceramics by an in situ hydrothermal process and were subjected to a simple ion exchange reaction for preparing the suitable catalyst material for Carbon nanotubes (CNTs) synthesis. The catalytic chemical vapour deposition (CCVD) technique was used to grow CNTs within the porous ceramics and the effect of growth time on the synthesized CNTs were investigated. Phase compositions of the samples were analysed by X-ray diffractometer (XRD). Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) were used for morphology, surface quality and structural analysis. Crystallinity, defects and yield were studied by Raman spectroscopy and thermogravimetric analysis (TGA). - Highlights: • Novel processing route of MWCNTs grown on Cobalt-zeolites-porous ceramics by CCVD. • CCVD time of 120 min produced MWCNTs with most prominent tube-like structure. • 120 min produced highest yield (19.46%) of CNTs with an I{sub D}/I{sub G} ratio of 0.88.

  18. Polymerization in situ by means of radiation gamma for the production of conducting polymeric composites

    International Nuclear Information System (INIS)

    Poblete Pulgar, Victor; Pilleux Cepeda, Mauricio; Fuenzalida Escobar, Victor; Alvarez Vargas, Mariela

    2002-01-01

    The nanocomposites synthesis of copper-methyl metacritate is made using copper spheres from 80 to 120 diameter nm, suspended in a methyl metacrilato (MMA) matrix, for different concentrations (5% to 30% of copper-v/v). The polymerization is carried out by means of gamma radiation, with 16 kGy dose applied 'in situ'. A high homogenous samples were obtained. The morphology and formation of the composite was studied by means of scanning electronic microscopy (SEM). The observed electric resistance is analyzed in function of the distance among electric contacts, meeting a strong dependence of the resistance with the homogeneous distribution of the metal in the composite. The obtained specific resistivities, in function of the concentration of the conductive metal, they are in the order of 42 Ωm for 10% v/v, being this critical concentration, the percolation threshold of the system. The obtained results show a material that is able to conserve principally the mechanical properties of the polymer and the electric properties of the conductive metal (author)

  19. In situ observations of the isotopic composition of methane at the Cabauw tall tower site

    Directory of Open Access Journals (Sweden)

    T. Röckmann

    2016-08-01

    Full Text Available High-precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS and a quantum cascade laser absorption spectroscopy (QCLAS-based technique for in situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw Experimental Site for Atmospheric Research (CESAR in the Netherlands and performed in situ, high-frequency (approx. hourly measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of (+0.25 ± 0.04 ‰ for δ13C and (−4.3 ± 0.4 ‰ for δD. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high-precision and high-temporal-resolution dataset not only reveals the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget when they are performed at multiple sites that are representative for

  20. Laser assisted soldering: microdroplet accumulation with a microjet device.

    Science.gov (United States)

    Chan, E K; Lu, Q; Bell, B; Motamedi, M; Frederickson, C; Brown, D T; Kovach, I S; Welch, A J

    1998-01-01

    We investigated the feasibility of a microjet to dispense protein solder for laser assisted soldering. Successive micro solder droplets were deposited on rat dermis and bovine intima specimens. Fixed laser exposure was synchronized with the jetting of each droplet. After photocoagulation, each specimen was cut into two halves at the center of solder coagulum. One half was fixed immediately, while the other half was soaked in phosphate-buffered saline for a designated hydration period before fixation (1 hour, 1, 2, and 7 days). After each hydration period, all tissue specimens were prepared for scanning electron microscopy (SEM). Stable solder coagulum was created by successive photocoagulation of microdroplets even after the soldered tissue exposed to 1 week of hydration. This preliminary study suggested that tissue soldering with successive microdroplets is feasible even with fixed laser parameters without active feedback control.

  1. Effect of Ag micro-alloying on the microstructure and properties of Cu-14Fe in situ composite

    International Nuclear Information System (INIS)

    Liu, K.M.; Lu, D.P.; Zhou, H.T.; Atrens, A.; Zou, J.; Yang, Y.L.; Zeng, S.M.

    2010-01-01

    This paper studied Ag micro-alloying in the deformation-processed Cu-14Fe in situ composite, by a comparison of Cu-14Fe and Cu-14Fe-0.06Ag. Each alloy was prepared by casting and processed into an in situ composite by hot and cold working. The microstructures were documented using light microscopy and scanning electron microscopy (SEM). The mechanical properties were measured with a tensile-testing machine. The electrical conductivity was measured with a micro-ohmmeter. For both alloys, the as-cast microstructure consisted of a Cu matrix and Fe dendrites; after hot and cold working the microstructure consisted of a Cu matrix containing Fe fibres elongated in the working direction. The as-cast Ag-containing alloy contained finer Fe dendrites. The Ag-containing in situ composite had thinner Fe fibres, higher tensile strength, higher ductility, and higher conductivity. The cold worked Cu-14Fe-0.06Ag in situ composite with cumulative cold deformation strain η = 7.8 (where η = ln(A 0 /A) and A 0 and A are the original and final cross-section areas, respectively), achieved a tensile strength of 930 MPa and a conductivity of 56%IACS (International Annealed Copper Standard; 17.241 nΩ m is defined as 100%IACS). The Ag micro-alloyed in situ composite had a combination of properties comparable to that of a much more expensive alloy containing much more Ag. After 1 h heat treatment at 300 deg. C, the tensile strength was increased to 950 MPa and the conductivity was increased to 56.4%IACS.

  2. In situ preparation of composite from conjugated polyschiff bases and multiwalled carbon nanotube: Synthesis, electrochromic, acidochromic properties

    International Nuclear Information System (INIS)

    Ma Lina; Cai Jiwei; Zhao Ping; Niu Haijun; Wang Cheng; Bai Xuduo; Wang Wen

    2012-01-01

    Graphical abstract: The introduction of carbon nanotubes greatly improves the photochromic property of the composites. Highlights: ► MWNTs/PSB composite was prepared by in situ polymerization with a new type of PSB. ► The introduction of carbon nanotubes greatly improves the photochromic property of the composites. ► The composites exhibited excellent thermal stability and reversible electrochemical behavior. - Abstract: Polyschiff base (PSB) which has the structure of C=N double bond is well known as conducting material with high thermal resistance, chemical and electrical properties. Recently, it was used as hole transporting material in organic light emitting diode (OLED), chemical sensor and electrochromic materials. Carbon nanotubes (CNTs) with excellent properties such as unique electrical, mechanical, optical and chemical properties are promising reinforcing materials for polymer composites which improve the comprehensive properties of polymers. In this paper, conjugated PSB-grafted multiwalled carbon nanotubes (MWNTs) composite was prepared by in situ polymerization. The resultant composites were characterized by thermogravimetric (TGA), scanning electron microscopy (SEM), UV–vis absorption, photoluminescence (PL), cyclic voltammograms (CV), infrared spectroscopy (IR) and Raman spectroscopy. The composites exhibited high thermal stability and excellent reversibilities of electrochromic, photochromic, acidochromic characteristics, with the color change from the light yellow to blue.

  3. Investigation and in situ removal of spatter generated during laser ablation of aluminium composites

    International Nuclear Information System (INIS)

    Popescu, A.C.; Delval, C.; Shadman, S.; Leparoux, M.

    2016-01-01

    Highlights: • Study of spatter generated during laser irradiation of an aluminium nanocomposite. • Number of droplets was 1.5–3 times higher for laser in depth vs surface focused beams. • High speed imaging revealed particles exploding in flight similar to a fireworks effect. • Three methods were selected for droplets removal in situ and the results are analyzed. - Abstract: Spatter generated during laser irradiation of an aluminium alloy nanocomposite (AlMg5 reinforced with Al_2O_3 nanoparticles) was monitored by high speed imaging. Droplets trajectory and speed were assessed by computerized image analysis. The effects of laser peak power and laser focusing on the plume expansion and expulsed droplet speeds were studied in air or under argon flow. It was found that the velocity of visible droplets expulsed laterally or at the end of the plume emission from the metal surface was not dependent on the plasma plume speed. The neighbouring area of irradiation sites was studied by optical and scanning electron microscopy. Droplets deposited on the surface were classified according to their size and counted using a digital image processing software. It was observed that the number of droplets on surface was 1.5–3 times higher when the laser beam was focused in depth as compared to focused beams, even though the populations average diameter were comparable. Three methods were selected for removing droplets in situ, during plume expansion: an argon gas jet crossing the plasma plume, a fused silica plate collector transparent to the laser wavelength placed parallel to the irradiated surface and a mask placed onto the aluminium composite surface. The argon gas jet was efficient only for low power irradiation conditions, the fused silica plate failed in all tested conditions and the mask was successful for all irradiation regimes.

  4. Expectations for Particulate Contamination Relevant to in Situ Atmospheric Sampling for Compositional Analysis at Uranus

    Science.gov (United States)

    Wong, M. H.

    2017-12-01

    NASA and ESA are considering options for in situ science with atmospheric entry probes to the ice giants Uranus and Neptune. Nominal probe entry mass is in the 300-kg range, although a miniaturized secondary probe option is being studied in the 30-kg range. In all cases, compositional sampling would commence near the 100-mbar level at Uranus, after ejection of the heat shield and deployment of the descent parachute. In this presentation, I review existing literature on the composition, mass loading, and vertical distribution of condensed material that the probe may encounter. Sample inlets for measurement of the gas composition should be heated to avoid potential buildup of condensate, which would block the flow of atmospheric gas into composition sensors. Heating rate and temperature values -- sufficient to keep sample inlets clean under various assumptions -- will be presented. Three main types of condensed material will be considered: Stratospheric hydrocarbon ices: Solar UV photolyzes CH4, leading to the production of volatile hydrocarbons with higher C/H ratios. These species diffuse from their production regions into colder levels where the ices of C2H2, C2H6, and C4H2 condense. Some studies have also considered condensation of C3H8, C4H10, C6H6, and C6H2. Gunk: The hydrocarbon ices are thought to become polymerized due to irradiation from solar UV. The exact composition of the resulting gunk is not known. Solid-state photochemical processing may produce the traces of reddish (blue-absorbing) haze material, present in the troposphere at temperatures warm enough to sublimate the simple hydrocarbon ices. Tropospheric ices: In the region accessible to probes under study (P < 10 bar), much thicker condensation clouds may form from volatile gases CH4, NH3, and H2S. If large amounts of NH3 are sequestered in the deeper H2O liquid cloud, then the S/N ratio could exceed 1 in the probe-accessible region of the atmosphere, leading to NH4SH and H2S ices below the CH4

  5. In situ formation of sintered cordierite–mullite nano–micro composites by utilizing of waste silica fume

    International Nuclear Information System (INIS)

    Khattab, R.M.; EL-Rafei, A.M.; Zawrah, M.F.

    2012-01-01

    Highlights: ► We succeeded to obtain in situ formed sintered cordierite–mullite nano–macro composites from waste and pure materials at 1400 °C. ► Their sinterability was greatly dependent on both firing temperature and composition. ► XRD patterns showed that the optimum temperature required for formation of sintered cordierite–mullite nano–macro composites was achieved at 1400 °C. ► The batch containing 70 wt.% cordierite and 30 wt.% mullite exhibited the best properties. ► Microstructures of the densified composites were composed of nano–macro cordierite–mullite structures. -- Abstract: This study aims at in situ formation of sintered cordierite–mullite nano–macro composites having high technological properties using waste silica fume, calcined ball clay, calcined alumina, and magnesia as starting materials. The starting materials were mixed in different ratios to obtain different cordierite–mullite composite batches in which the cordierite contents ranged from 50 to 100 wt.%. The batches were uni-axially pressed at 100 MPa and sintered at 1350, 1400 and 1450 °C to select the optimum temperature required for cordierite–mullite nano–macro composites formation. The formed phases were identified by X-ray diffraction (XRD) pattern. The sintering parameters in terms of bulk density (BD) and apparent porosity (AP) were determined. The microstructure of composites has been investigated by scanning electron microscope (SEM). Cold crushing strength (CCS) of the sintered batches was evaluated. The result revealed that the cordierite–mullite nano–macro composites were in-situ formed at 1400 °C. The batch containing 70 wt.% cordierite showed good physical and mechanical properties.

  6. Micro/nanoscale mechanical characterization and in situ observation of cracking of laminated Si3N4/BN composites

    International Nuclear Information System (INIS)

    Li Xiaodong; Zou Linhua; Ni Hai; Reynolds, Anthony P.; Wang Changan; Huang Yong

    2008-01-01

    Micro/nanoscale mechanical characterization of laminated Si 3 N 4 /BN composites was carried out by nanoindentation techniques. A custom-designed micro mechanical tester was integrated with an optical microscope and an atomic force microscope to perform in situ three-point bending tests on notched Si 3 N 4 /BN composite bend specimens where the crack initiation and propagation were imaged simultaneously with the optical microscope and atomic force microscope during bending loading. The whole fracture process was in situ captured. It was found that crack deflection was initiated/induced by the pre-existing microvoids and microcracks in BN interfacial layers. New fracture mechanisms were proposed to provide guidelines for the design of biomimetic nacre-like composites

  7. A simple stir casting technique for the preparation of in situ Fe-aluminides reinforced Al-matrix composites

    Directory of Open Access Journals (Sweden)

    Susanta K. Pradhan

    2016-09-01

    Full Text Available This article presents a simple stir casting technique for the development of Fe-aluminides particulate reinforced Al-matrix composites. It has been demonstrated that stirring of super-heated Al-melt by a mild steel plate followed by conventional casting and hot rolled results in uniform dispersion of in situ Al13Fe4 particles in the Al matrix; the amount of reinforcement is found to increase with increasing melt temperature. With reference to base alloy, the developed composite exhibits higher hardness and improved tensile strength without much loss of ductility; since, composite like base alloy undergoes ductile mode of fracture.

  8. Microstructural and mechanical properties analysis of extruded Sn–0.7Cu solder alloy

    Directory of Open Access Journals (Sweden)

    Abdoul-Aziz Bogno

    2015-01-01

    Full Text Available The properties and performance of lead-free solder alloys such as fluidity and wettability are defined by the alloy composition and solidification microstructure. Rapid solidification of metallic alloys is known to result in refined microstructures with reduced microsegregation and improved mechanical properties of the final products as compared to normal castings. The rapidly solidified Sn-based solders by melt spinning were shown to be suitable for soldering with low temperature and short soldering duration. In the present study, rapidly solidified Sn–0.7 wt.%Cu droplets generated by impulse atomization (IA were achieved as well as directional solidification under transient conditions at lower cooling rate. This paper reports on a comparative study of the rapidly solidified and the directionally solidified samples. Different but complementary characterization techniques were used to fully analyze the solidification microstructures of the samples obtained under the two cooling regimes. These include X-ray diffractometry (XRD and scanning electron microscopy (SEM. In order to compare the tensile strength and elongation to fracture of the directionally solidified ingot and strip castings with the atomized droplet, compaction and extrusion of the latter were carried out. It was shown that more balanced and superior tensile mechanical properties are available for the hot extruded samples from compacted as-atomized Sn–0.7 wt.%Cu droplets. Further, elongation-to-fracture was 2–3× higher than that obtained for the directionally solidified samples.

  9. Potential Use of In Situ Material Composites such as Regolith/Polyethylene for Shielding Space Radiation

    Science.gov (United States)

    Theriot, Corey A.; Gersey, Buddy; Bacon, Eugene; Johnson, Quincy; Zhang, Ye; Norman, Jullian; Foley, Ijette; Wilkins, Rick; Zhou, Jianren; Wu, Honglu

    2010-01-01

    NASA has an extensive program for studying materials and methods for the shielding of astronauts to reduce the effects of space radiation when on the surfaces of the Moon and Mars, especially in the use of in situ materials native to the destination reducing the expense of materials transport. The most studied material from the Moon is Lunar regolith and has been shown to be as efficient as aluminum for shielding purposes (1). The addition of hydrogenous materials such as polyethylene should increase shielding effectiveness and provide mechanical properties necessary of structural materials (2). The neutron radiation shielding effectiveness of polyethylene/regolith stimulant (JSC-1A) composites were studied using confluent human fibroblast cell cultures exposed to a beam of high-energy spallation neutrons at the 30deg-left beam line (ICE house) at the Los Alamos Neutron Science Center. At this angle, the radiation spectrum mimics the energy spectrum of secondary neutrons generated in the upper atmosphere and encountered when aboard spacecraft and high-altitude aircraft. Cell samples were exposed in series either directly to the neutron beam, within a habitat created using regolith composite blocks, or behind 25 g/sq cm of loose regolith bulk material. In another experiment, cells were also exposed in series directly to the neutron beam in T-25 flasks completely filled with either media or water up to a depth of 20 cm to test shielding effectiveness versus depth and investigate the possible influence of secondary particle generation. All samples were sent directly back to JSC for sub-culturing and micronucleus analysis. This presentation is of work performed in collaboration with the NASA sponsored Center for Radiation Engineering and Science for Space Exploration (CRESSE) at Prairie View A&M.

  10. Shock Wave Response of Iron-based In Situ Metallic Glass Matrix Composites.

    Science.gov (United States)

    Khanolkar, Gauri R; Rauls, Michael B; Kelly, James P; Graeve, Olivia A; Hodge, Andrea M; Eliasson, Veronica

    2016-03-02

    The response of amorphous steels to shock wave compression has been explored for the first time. Further, the effect of partial devitrification on the shock response of bulk metallic glasses is examined by conducting experiments on two iron-based in situ metallic glass matrix composites, containing varying amounts of crystalline precipitates, both with initial composition Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4. The samples, designated SAM2X5-600 and SAM2X5-630, are X-ray amorphous and partially crystalline, respectively, due to differences in sintering parameters during sample preparation. Shock response is determined by making velocity measurements using interferometry techniques at the rear free surface of the samples, which have been subjected to impact from a high-velocity projectile launched from a powder gun. Experiments have yielded results indicating a Hugoniot Elastic Limit (HEL) to be 8.58 ± 0.53 GPa for SAM2X5-600 and 11.76 ± 1.26 GPa for SAM2X5-630. The latter HEL result is higher than elastic limits for any BMG reported in the literature thus far. SAM2X5-600 catastrophically loses post-yield strength whereas SAM2X5-630, while showing some strain-softening, retains strength beyond the HEL. The presence of crystallinity within the amorphous matrix is thus seen to significantly aid in strengthening the material as well as preserving material strength beyond yielding.

  11. Investigation on microstructural characterization of in situ TiB/Al metal matrix composite by laser cladding

    International Nuclear Information System (INIS)

    Xu Jiang; Li Zhengyang; Zhu Wenhui; Liu Zili; Liu Wenjin

    2007-01-01

    The aluminum matrix composite (AMC) coating reinforced with TiB was prepared utilizing in situ synthesized technique by laser cladding. Microstructural characterization and dry sliding wear behavior of in situ TiB/Al metal matrix composite were studied by SEM, XRD, TEM and Pin-on-disc friction and wear tester. The phase structure of the composite coating consists of α-Al, TiB, Al 3 Ti and Al 3 Fe. It has been found that the shape of in situ synthesized TiB is mainly taken on micro-magnitude lump and nano-magnitude whisker. Owing to B27 structure of TiB, the TiB has an anisotropy axis of growth, which results in the TiB strip and whisker preferring grown along [0 1 0] direction. It is worth to notice that the novel microstructure inside of TiB is particle and strip Al 5 Fe 2 phase and definite crystallographic relationship between the Al 5 Fe 2 phase and TiB has been determined by selected area diffraction pattern. The wear tests results show that the composite coatings can only improve wear resistance at the lower applied load (below 26.7 N), but at higher applied load (26.7-35.6 N) the wear resistance behavior of the coating is worsened due to the fracture and pullout of reinforcement phase

  12. Preparation and properties of in-situ growth of carbon nanotubes reinforced hydroxyapatite coating for carbon/carbon composites

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shoujie, E-mail: jlliushoujie@126.com; Li, Hejun, E-mail: lihejun@nwpu.edu.cn; Su, Yangyang, E-mail: suyangyang@mail.nwpu.edu.cn; Guo, Qian, E-mail: 1729299905@163.com; Zhang, Leilei, E-mail: zhangleilei@nwpu.edu.cn

    2017-01-01

    Carbon nanotubes (CNTs) possess excellent mechanical properties for their role playing in reinforcement as imparting strength to brittle hydroxyapatite (HA) bioceramic coating. However, there are few reports relating to the in-situ grown carbon nanotubes reinforced hydroxyapatite (CNTs-HA) coating. Here we demonstrate the potential application in reinforcing biomaterials by an attempt to use in-situ grown of CNTs strengthen HA coating, using a combined method composited of injection chemical vapor deposition (ICVD) and pulsed electrodeposition. The microstructure, phases and chemical compositions of CNTs-HA coatings were characterized by various advanced methods. The scanning electron microscopy (SEM) images indicated that CNTs-HA coatings avoided the inhomogeneous dispersion of CNTs inside HA coating. The result show that the interfacial shear strength between CNTs-HA coating and the C/C composite matrix reaches to 12.86 ± 1.43 MPa. Potenitodynamic polarization and electrochemical impedance spectroscopy (EIS) studies show that the content of CNTs affects the corrosion resistance of CNTs-HA coating. Cell culturing and simulated body fluid test elicit the biocompatibility with living cells and bioactivity of CNTs-HA coatings, respectively. - Highlights: • A novel bioceramic composite coating of hydroxyapatite reinforced with in-situ grown carbon nanotubes was fabricated. • The doping of carbon nanotubes had almost no impact on the biocompatibility of hydroxyapatite coatings. • The doping of carbon nanotubes improved corrosion resistance of hydroxyapatite coatings in simulated human body solution.

  13. Investigation on microstructural characterization of in situ TiB/Al metal matrix composite by laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Xu Jiang [Department of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China)]. E-mail: xujiang73@nuaa.edu.cn; Li Zhengyang [Key Laboratory for Advanced Materials Manufacturing Processing, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China); Zhu Wenhui [Department of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China); Liu Zili [Department of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China); Liu Wenjin [Key Laboratory for Advanced Materials Manufacturing Processing, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China)

    2007-02-25

    The aluminum matrix composite (AMC) coating reinforced with TiB was prepared utilizing in situ synthesized technique by laser cladding. Microstructural characterization and dry sliding wear behavior of in situ TiB/Al metal matrix composite were studied by SEM, XRD, TEM and Pin-on-disc friction and wear tester. The phase structure of the composite coating consists of {alpha}-Al, TiB, Al{sub 3}Ti and Al{sub 3}Fe. It has been found that the shape of in situ synthesized TiB is mainly taken on micro-magnitude lump and nano-magnitude whisker. Owing to B27 structure of TiB, the TiB has an anisotropy axis of growth, which results in the TiB strip and whisker preferring grown along [0 1 0] direction. It is worth to notice that the novel microstructure inside of TiB is particle and strip Al{sub 5}Fe{sub 2} phase and definite crystallographic relationship between the Al{sub 5}Fe{sub 2} phase and TiB has been determined by selected area diffraction pattern. The wear tests results show that the composite coatings can only improve wear resistance at the lower applied load (below 26.7 N), but at higher applied load (26.7-35.6 N) the wear resistance behavior of the coating is worsened due to the fracture and pullout of reinforcement phase.

  14. Photocatalytic and microwave absorbing properties of polypyrrole/Fe-doped TiO2 composite by in situ polymerization method

    International Nuclear Information System (INIS)

    Li Qiaoling; Zhang Cunrui; Li Jianqiang

    2011-01-01

    Research highlights: → Polypyrrole/Fe-doped TiO 2 composite is prepared by in situ polymerization of pyrrole on the Fe-doped TiO 2 template. → The Fe-doped TiO 2 microbelts are prepared by sol-gel method using the absorbent cotton template for the first time. → Then the Fe-doped TiO 2 microbelts are used as template for the preparation of polypyrrole/Fe-doped TiO 2 composites. → The structure, morphology and properties of the composites are characterized with scanning electron microscope (SEM), IR, Net-work Analyzer. → A possible formation mechanism of Fe-doped TiO 2 microbelts and polypyrrole/Fe-doped TiO 2 composites has been proposed. → The effect of the mol ratio of pyrrole/Fe-doped TiO 2 on the photocatalysis properties and microwave loss properties of the composites is investigated. - Abstract: The Fe-doped TiO 2 microbelts were prepared by sol-gel method using the absorbent cotton template for the first time. Then the Fe-doped TiO 2 microbelts were used as templates for the preparation of polypyrrole/Fe-doped TiO 2 composites. Polypyrrole/Fe-doped TiO 2 composites were prepared by in situ polymerization of pyrrole on the Fe-doped TiO 2 template. The structure, morphology and properties of the composites were characterized with scanning electron microscope (SEM), FTIR, Net-work Analyzer. The possible formation mechanisms of Fe-doped TiO 2 microbelts and polypyrrole/Fe-doped TiO 2 composites have been proposed. The effect of the molar ratio of pyrrole/Fe-doped TiO 2 on the photocatalytic properties and microwave loss properties of the composites was investigated.

  15. Tribological properties and lubrication mechanism of in situ graphene-nickel matrix composite impregnated with lubricating oil

    Science.gov (United States)

    Lei, Yu; Du, Jinfang; Pang, Xianjuan; Wang, Haizhong; Yang, Hua; Jiang, Jinlong

    2018-05-01

    A solid-liquid synergetic lubricating system has been designed to develop a novel self-lubricating nickel matrix composite. The graphene-nickel (G-Ni) matrix composite with porous structure was fabricated by in situ growing graphene in bulk nickel using a powder metallurgy method. The porous structures of the composite were used to store polyalphaolefin (PAO) oil for self-lubricating. It is found that the G-Ni matrix composite under oil lubrication condition exhibited superior tribological properties as compared to pure nickel and the composite under dry sliding condition. The prestored oil was released from pores to the sliding surface forming a lubricating oil film during friction process. This lubricating oil film can protect the worn surface from severe oxidation, and help the formation and transfer of a carbon-based solid tribofilm derived from graphene and lubricating oil. This solid (graphene)-liquid (oil) synergistic lubricating mechanism is responsible for the reduction of friction coefficient and improvement of wear resistance of the in situ fabricated G-Ni matrix composite.

  16. Solder bond requirement for large, built-up, high-performance conductors

    International Nuclear Information System (INIS)

    Willig, R.L.

    1981-01-01

    Some large built-up conductors fabricated for large superconducting magnets are designed to operate above the maximum recovery current. Because the stability of these conductors is sensitive to the quality of the solder bond joining the composite superconductor to the high-conductivity substrate, a minimum bond requirement is necessary. The present analysis finds that the superconductor is unstable and becomes abruptly resistive when there are temperature excursions into the current sharing region of a poorly bonded conductor. This abrupt transition, produces eddy current heating in the vicinity of the superconducting filaments and causes a sharp reduction in the minimum propagating zone (MPZ) energy. This sensitivity of the MPZ energy to the solder bond contact area is used to specify a minimum bond requirement. For the superconducting MHD magnet built for the Component Development Integration Facility (CDIF), the minimum bonded surface area is .68 cm/sup 2//cm which is 44% of the composite perimeter. 5 refs

  17. Physical and chemical composition and in situ degradability of macauba palm cake and leaves

    Directory of Open Access Journals (Sweden)

    Vanda Patrícia Barros Ferreira

    2013-12-01

    Full Text Available Macauba palm coconuts are rich in essential nutrients for animal feed formulation and after oil extraction, a large amount of residual biomass is produced, which must be used rationally to environmental preservation. This study aimed to determine the nutritional value of macauba palm (Acrocomia aculeata, cake and leaves, for its physical and chemical composition, dry matter (DM in vitro digestibility (IVD and in situ degradability. The test of in situ degradability was done using three rumen fistulated cattle. Analytical determinations were performed in the laboratory of Animal Nutrition of Instituto de Zootecnia, Nova Odessa-SP, Brazil. Six replicates were used for each analytical determination and were calculated the standard error. Macauba cake chemically assessed showed a low protein content (CP 4.5% and high content of acid detergent fibre (ADF 39.7% and average levels of neutral detergent fibre (NDF 52.5%. ADF and NDF were the macauba palm cake majority fractions compared NDF and ADF (respectively of cocoa cake (37.6 and 45.5%, sunflower cake (28.2 and 38.4%, corn meal (11.3 and 20.2% and peanut cake (15.4 and 21.0. Macauba palm leaves had a good protein content (12.0% and fiber content comparable to tropical grass of good nutritional value. They can be used with no restriction on ruminants’ diets. The macauba palm cake high levels of lignin (16.5% justify the low dry matter IVD percentage (48%, while the leaves had 58%.of IVD. Macauba leaves total digestible nutrients (TDN 59.0% is similar to TDN usually observed for forages. Macauba cake can be considered (TDN = 64.0% similar to energetic food, due to the fat content (6.4%, however the high content of lignin (16.5% can limit its consumption. Macauba palm cake showed high ruminal degradability of DM and CP (fraction a = 51.3 and 59.9, respectively, while macauba palm leaves hah low solubility of DM and CP (fraction a = 3.18 and 5.28, respectively. Thus, the higher CP macauba leaves

  18. The creep behavior of In-Ag eutectic solder joints

    International Nuclear Information System (INIS)

    Reynolds, H.L.; Kang, S.H.; Morris, J.W. Jr.; Univ. of California, Berkeley, CA

    1999-01-01

    The addition of 3 wt.% Ag to In results in a eutectic composition with improved mechanical properties while only slightly lowering the melting temperature. Steady-state creep properties of In-Ag eutectic solder joints have been measured using constant load tests at 0, 30, 60, and 90 C. Constitutive equations are derived to describe the creep behavior. The data are well represented by an equation of the form proposed by Dorn: a power-law equation applies to each independent creep mechanism. Two parallel mechanisms were observed for the In-Ag eutectic joints. The high-stress mechanism is a bulk mechanism with a thermal dependence dominated by the thermal dependence of creep in the In-rich matrix. The low-stress mechanism is a grain boundary mechanism. Results of this work are discussed with regard to creep behavior of typical eutectic systems

  19. Development of Sn-Ag-Cu-X Solders for Electronic Assembly by Micro-Alloying with Al

    Science.gov (United States)

    Boesenberg, Adam J.; Anderson, Iver E.; Harringa, Joel L.

    2012-07-01

    Of Pb-free solder choices, an array of solder alloys based on the Sn-Ag-Cu (SAC) ternary eutectic ( T eut = 217°C) composition have emerged with potential for broad use, including ball grid array (BGA) joints that cool slowly. This work investigated minor substitutional additions of Al (0.05Al), but the suppression effect faded for >0.20Al. Undercooling suppression did not correlate specifically with blade suppression since it became significant at 0.10Al and increased continuously with greater Al to 0.25Al. Surprisingly, an intermediate range of Al content (0.10 wt.% to 0.20 wt.% Al) promoted formation of significant populations of 2- μm to 5- μm faceted Cu-Al particles, identified as Cu33Al17, that clustered at the top of the solder joint matrix and exhibited extraordinary hardness. Clustering of Cu33Al17 was attributed to its buoyancy, from a lower density than Sn liquid, and its early position in the nucleation sequence within the solder matrix, permitting unrestricted migration to the top interface. Joint microstructures and implications for the full nucleation sequence for these SAC + Al solder joints are discussed, along with possible benefits from the clustered particles for improved thermal cycling resistance.

  20. Reactivity of sulfide-containing silane toward boehmite and in situ modified rubber/boehmite composites by the silane

    Science.gov (United States)

    Lin, Tengfei; Zhu, Lixin; Chen, Weiwei; Wu, Siwu; Guo, Baochun; Jia, Demin

    2013-09-01

    The silanization reaction between boehmite (BM) nanoplatelets and bis-[3-(triethoxysilyl)-propyl]-tetrasulfide (TESPT) was characterized in detail. Via such modification process, the grafted sulfide moieties on the BM endow reactivity toward rubber and substantially improved hydrophobicity for BM. Accordingly, TESPT was employed as in situ modifier for the nitrile rubber (NBR)/BM compounds to improve the mechanical properties of the reinforced vulcanizates. The effects of BM content and in situ modification on the mechanical properties, curing characteristics and morphology were investigated. BM was found to be effective in improving the mechanical performance of NBR vulcanizates. The NBR/BM composites could be further strengthened by the incorporation of TESPT. The interfacial adhesion of NBR/BM composites was obviously improved by the addition of TESPT. The substantially improved mechanical performance was correlated to the interfacial reaction and the improved dispersion of BM in rubber matrix.

  1. Microstructure and mechanical properties of Sn-9Zn-xAl2O3 nanoparticles (x=0–1) lead-free solder alloy: First-principles calculation and experimental research

    International Nuclear Information System (INIS)

    Xing, Wen-qing; Yu, Xin-ye; Li, Heng; Ma, Le; Zuo, Wei; Dong, Peng; Wang, Wen-xian; Ding, Min

    2016-01-01

    This paper studies microstructure and mechanical properties of Sn-9Zn-x Al 2 O 3 nanoparticles (x=0–1) lead-free solder alloy. The interface structure, interface energy and electronic properties of Al 2 O 3 /Sn9Zn interface are investigated by first-principle calculation. On the experimental part, in comparison with the plain Sn-9Zn solder, the Al 2 O 3 nanoparticles incorporated into the solder matrix can inhibit the growth of coarse dendrite Sn-Zn eutectic structure and refine grains of the composite solders during the solidification process of the alloys. Moreover, the microhardness and average tensile strength of the solders with addition of Al 2 O 3 nanoparticles increased with the increasing weight percentages of Al 2 O 3 nanoparticles. These improved mechanical properties can be attributed to the microstructure developments and the dispersed Al 2 O 3 nanoparticles.

  2. Characterization of Multifunctional Carbon Nanotube Yarns: In-situ Strain Sensing and Composite Reinforcement

    Science.gov (United States)

    Page, Christian David

    A large body of scientific research and development worldwide has focused on the unprecedented structural/functional properties of carbon nanotubes (CNT), yet translation of these unique properties of CNTs to macroscopic materials has been slow to develop. CNT yarns are an appealing application for CNTs; their lightweight and small diameter can allow for them to be embedded into composite materials. Since the individual nanotubes have shown to have incredibly high strength, stiffness, and strain sensitivity, CNT yarns have the potential to be highly effective for in-situ structural health monitoring of advanced materials and structures. This work identifies the sources for losses in strength and electromechanical sensitivity. This is done by first understanding the physics involved with a CNT yarn under axial strain. Since this material is not a Newtonian solid, the stress-strain relationships are dissimilar to conventional materials, exhibiting a three zone behavior. This is present in both the stress-strain and resistance-strain relationships. A tensile test performed in-situ within a scanning electron microscope showed that the diameter of the yarn reduced greatly during tension, which indicates that the volume is not constant; therefore, the intratube/intrabundle load transfer efficiency and electrical conductivity change significantly under strain. Observation of this phenomenon helps elucidate the source for loss in the translation from nanoscopic CNTs to the macroscopic CNT yarns. Following the observation that the CNT yarn is not a solid body mechanics system, investigation into the long-standing field of textile engineering helped to identify that the CNT yarn structural hierarchy should be re-evaluated. Literary review reveals that the predominant base morphology of CNT yarns is bundles of CNTs as opposed to individual CNTs. Furthermore, in conventional textiles, it is well known that the base morphology (in textiles this is the "fiber") will bundle

  3. Microstructural Control via Copious Nucleation Manipulated by In Situ Formed Nucleants: Large-Sized and Ductile Metallic Glass Composites.

    Science.gov (United States)

    Song, Wenli; Wu, Yuan; Wang, Hui; Liu, Xiongjun; Chen, Houwen; Guo, Zhenxi; Lu, Zhaoping

    2016-10-01

    A novel strategy to control the precipitation behavior of the austenitic phase, and to obtain large-sized, transformation-induced, plasticity-reinforced bulk metallic glass matrix composites, with good tensile properties, is proposed. By inducing heterogeneous nucleation of the transformable reinforcement via potent nucleants formed in situ, the characteristics of the austenitic phase are well manipulated. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Evaluating print performance of Sn-Ag-Cu lead-free solder pastes used in electronics assembly process

    Science.gov (United States)

    Mallik, S.; Bauer, R.; Hübner, F.; Ekere, N. N.

    2011-01-01

    Solder paste is the most widely used interconnection material in the electronic assembly process for attaching electronic components/devices directly onto the surface of printed circuit boards, using stencil printing process. This paper evaluates the performance of three different commercially available Sn-Ag-Cu solder pastes formulated with different particle size distributions (PSD), metal content and alloy composition. A series of stencil printing tests were carried out using a specially designed stencil of 75 μm thickness and apertures of 300×300 μm2 dimension and 500 μm pitch sizes. Solder paste printing behaviors were found related to attributes such as slumping and surface tension and printing performance was correlated with metal content and PSD. The results of the study should benefit paste manufacturers and SMT assemblers to improve their products and practices.

  5. Effect of Solder Flux Residues on Corrosion of Electronics

    DEFF Research Database (Denmark)

    Hansen, Kirsten Stentoft; Jellesen, Morten Stendahl; Møller, Per

    2009-01-01

    Flux from ‘No Clean’ solder processes can cause reliability problems in the field due to aggressive residues, which may be electrical conducting or corrosive in humid environments. The solder temperature during a wave solder process is of great importance to the amount of residues left on a PCBA...... testing and use in the field, consequences and recommendations are given. Failures, caused by harsh[1] customer environments, are not covered in this paper....

  6. Mechanical properties of soldered joints of niobium base alloys

    International Nuclear Information System (INIS)

    Grishin, V.L.

    1980-01-01

    Mechanical properties of soldered joints of niobium alloys widely distributed in industry: VN3, VN4, VN5A, VN5AE, VN5AEP etc., 0.6-1.2 mm thick are investigated. It is found out that the usage of zirconium-vanadium, titanium-tantalum solders for welding niobium base alloys permits to obtain soldered joints with satisfactory mechanical properties at elevated temperatures

  7. In situ laser-induced breakdown spectroscopy measurements of chemical compositions in stainless steels during tungsten inert gas welding

    Science.gov (United States)

    Taparli, Ugur Alp; Jacobsen, Lars; Griesche, Axel; Michalik, Katarzyna; Mory, David; Kannengiesser, Thomas

    2018-01-01

    A laser-induced breakdown spectroscopy (LIBS) system was combined with a bead-on-plate Tungsten Inert Gas (TIG) welding process for the in situ measurement of chemical compositions in austenitic stainless steels during welding. Monitoring the weld pool's chemical composition allows governing the weld pool solidification behavior, and thus enables the reduction of susceptibility to weld defects. Conventional inspection methods for weld seams (e.g. ultrasonic inspection) cannot be performed during the welding process. The analysis system also allows in situ study of the correlation between the occurrence of weld defects and changes in the chemical composition in the weld pool or in the two-phase region where solid and liquid phase coexist. First experiments showed that both the shielding Ar gas and the welding arc plasma have a significant effect on the selected Cr II, Ni II and Mn II characteristic emissions, namely an artificial increase of intensity values via unspecific emission in the spectra. In situ investigations showed that this artificial intensity increase reached a maximum in presence of weld plume. Moreover, an explicit decay has been observed with the termination of the welding plume due to infrared radiation during sample cooling. Furthermore, LIBS can be used after welding to map element distribution. For austenitic stainless steels, Mn accumulations on both sides of the weld could be detected between the heat affected zone (HAZ) and the base material.

  8. Preparation and mechanical properties of in situ TiC{sub x}–Ni (Si, Ti) alloy composites

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenjuan [Institute of Materials Science and Engineering, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Zhai, Hongxiang, E-mail: hxzhai@sina.com [Institute of Materials Science and Engineering, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Chen, Lin; Huang, Zhenying [Institute of Materials Science and Engineering, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Bei, Guoping; Baumgärtner, Christoph; Greil, Peter [Department of Materials Science (Glass and Ceramics), University of Erlangen-Nuernberg, Martensstr. 5, 91058 Erlangen (Germany)

    2014-10-20

    Novel in situ TiC{sub x} reinforced Ni (Si, Ti) alloy composites with superior mechanical properties were prepared at 1250 °C for 30 min by pressureless sintering Ti{sub 3}SiC{sub 2} (10 and 20 vol%) and Ni as precursors. The Ti{sub 3}SiC{sub 2} particles decomposed into substoichiometric TiC{sub x} phase, while the additional Si and partial Ti atoms derived from Ti{sub 3}SiC{sub 2} diffused into Ni matrix to form Ni (Si, Ti) alloy. The in situ formed TiC{sub x} phases are mainly dispersed on the grain boundaries of the Ni (Si, Ti) alloying, forming a strong skeleton and refining the microstructures of the metal matrix. The hardness, the yield stress σ{sub 0.2%} and ultimate compressive strength of 20.6 vol%TiC{sub x}–Ni(Si, Ti) composite can reach 2.15±0.04 GPa, 466.8±55.8 MPa and 733.3±78.4 MPa, respectively. The enhanced mechanical properties of TiC{sub x}–Ni(Si, Ti) composites are due to the in situ formation of TiC{sub x} skeleton, the refined microstructures of Ni (Si, Ti) alloys and solid solution effects as well as good wettability between TiC{sub x} and Ni (Si, Ti) matrix.

  9. Superior high creep resistance of in situ nano-sized TiCx/Al-Cu-Mg composite.

    Science.gov (United States)

    Wang, Lei; Qiu, Feng; Zhao, Qinglong; Zha, Min; Jiang, Qichuan

    2017-07-03

    The tensile creep behavior of Al-Cu-Mg alloy and its composite containing in situ nano-sized TiC x were explored at temperatures of 493 K, 533 K and 573 K with the applied stresses in the range of 40 to 100 MPa. The composite reinforced by nano-sized TiC x particles exhibited excellent creep resistance ability, which was about 4-15 times higher than those of the unreinforced matrix alloy. The stress exponent of 5 was noticed for both Al-Cu-Mg alloy and its composite, which suggested that their creep behavior was related to dislocation climb mechanism. During deformation at elevated temperatures, the enhanced creep resistance of the composite was mainly attributed to two aspects: (a) Orowan strengthening and grain boundary (GB) strengthening induced by nano-sized TiC x particles, (b) θ' and S' precipitates strengthening.

  10. Loading rate and test temperature effects on fracture of in situ niobium silicide-niobium composites

    International Nuclear Information System (INIS)

    Rigney, J.D.; Lewandowski, J.J.

    1996-01-01

    Arc cast, extruded, and heat-treated in situ composites of niobium silicide (Nb 5 Si 3 ) intermetallic with niobium phases (primary--Nb p and secondary--Nb s ) exhibited high fracture resistance in comparison to monolithic Nb 5 Si 3 . In toughness tests conducted at 298 K and slow applied loading rates, the fracture process proceeded by the microcracking of the Nb 5 Si 3 and plastic deformation of the Nb p and Nb s phases, producing resistance-curve behavior and toughnesses of 28 MPa√m with damage zone lengths less than 500 microm. The effects of changes in the Nb p yield strength and fracture behavior on the measured toughnesses were investigated by varying the loading rates during fracture tests at both 77 and 298 K. Quantitative fractography was utilized to completely characterize each fracture surface created at 298 K in order to determine the type of fracture mode (i.e., dimpled, cleavage) exhibited by the Nb p . Specimens tested at either higher loading rates or lower test temperatures consistently exhibited a greater amount of cleavage fracture in the Nb p , while the Nb s always remained ductile. However, the fracture toughness values determined from experiments spanning six orders of magnitude in loading rate at 298 and 77 K exhibited little variation, even under conditions when the majority of Nb p phases failed by cleavage at 77 K. The changes in fracture mode with increasing loading rate and/or decreasing test temperature and their effects on fracture toughness are rationalized by comparison to existing theoretical models

  11. Laboratory investigations of Titan haze formation: In situ measurement of gas and particle composition

    Science.gov (United States)

    Hörst, Sarah M.; Yoon, Y. Heidi; Ugelow, Melissa S.; Parker, Alex H.; Li, Rui; de Gouw, Joost A.; Tolbert, Margaret A.

    2018-02-01

    Prior to the arrival of the Cassini-Huygens spacecraft, aerosol production in Titan's atmosphere was believed to begin in the stratosphere where chemical processes are predominantly initiated by far ultraviolet (FUV) radiation. However, measurements taken by the Cassini Ultraviolet Imaging Spectrograph (UVIS) and Cassini Plasma Spectrometer (CAPS) indicate that haze formation initiates in the thermosphere where there is a greater flux of extreme ultraviolet (EUV) photons and energetic particles available to initiate chemical reactions, including the destruction of N2. The discovery of previously unpredicted nitrogen species in measurements of Titan's atmosphere by the Cassini Ion and Neutral Mass Spectrometer (INMS) indicates that nitrogen participates in the chemistry to a much greater extent than was appreciated before Cassini. The degree of nitrogen incorporation in the haze particles is important for understanding the diversity of molecules that may be present in Titan's atmosphere and on its surface. We have conducted a series of Titan atmosphere simulation experiments using either spark discharge (Tesla coil) or FUV photons (deuterium lamp) to initiate chemistry in CH4/N2 gas mixtures ranging from 0.01% CH4/99.99% N2 to 10% CH4/90% N2. We obtained in situ real-time measurements using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) to measure the particle composition as a function of particle size and a proton-transfer ion-trap mass spectrometer (PIT-MS) to measure the composition of gas phase products. These two techniques allow us to investigate the effect of energy source and initial CH4 concentration on the degree of nitrogen incorporation in both the gas and solid phase products. The results presented here confirm that FUV photons produce not only solid phase nitrogen bearing products but also gas phase nitrogen species. We find that in both the gas and solid phase, nitrogen is found in nitriles rather than amines and that both the

  12. In-situ polymerisation of fully bioresorbable polycaprolactone/phosphate glass fibre composites: In vitro degradation and mechanical properties.

    Science.gov (United States)

    Chen, Menghao; Parsons, Andrew J; Felfel, Reda M; Rudd, Christopher D; Irvine, Derek J; Ahmed, Ifty

    2016-06-01

    Fully bioresorbable composites have been investigated in order to replace metal implant plates used for hard tissue repair. Retention of the composite mechanical properties within a physiological environment has been shown to be significantly affected due to loss of the integrity of the fibre/matrix interface. This study investigated phosphate based glass fibre (PGF) reinforced polycaprolactone (PCL) composites with 20%, 35% and 50% fibre volume fractions (Vf) manufactured via an in-situ polymerisation (ISP) process and a conventional laminate stacking (LS) followed by compression moulding. Reinforcing efficiency between the LS and ISP manufacturing process was compared, and the ISP composites revealed significant improvements in mechanical properties when compared to LS composites. The degradation profiles and mechanical properties were monitored in phosphate buffered saline (PBS) at 37°C for 28 days. ISP composites revealed significantly less media uptake and mass loss (pproperties of ISP composites were substantially higher (p<0.0001) than those of the LS composites, which showed that the ISP manufacturing process provided a significantly enhanced reinforcement effect than the LS process. During the degradation study, statistically higher flexural property retention profiles were also seen for the ISP composites compared to LS composites. SEM micrographs of fracture surfaces for the LS composites revealed dry fibre bundles and poor fibre dispersion with polymer rich zones, which indicated poor interfacial bonding, distribution and adhesion. In contrast, evenly distributed fibres without dry fibre bundles or polymer rich zones, were clearly observed for the ISP composite samples, which showed that a superior fibre/matrix interface was achieved with highly improved adhesion. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. In situ self-polymerization of unsaturated metal methacrylate and its dispersion mechanism in rubber-based composites

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Shipeng; Zhou, Yao; Yao, Lu [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Liqun [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Chan, Tung W. [Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, VA 24061 (United States); Liang, Yongri [Beijing National Laboratory for Molecular Sciences, Joint Laboratory of Polymer Science and Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Li, E-mail: LiuL@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2013-11-10

    Highlights: • In situ self-polymerization of unsaturated metal methacrylate was investigated mainly by the thermal effect. • UMM with low melting point can self-polymerize to a large extent. • The fine dispersion phase is composed of poly(UMM) nanoparticles formed by in situ self-polymerization in the rubber matrix. • The UMM crystals in the presence of peroxide and rubber undergo the processes of melting, diffusion, polymerization, and phase separation in this order. - Abstract: Unsaturated metal methacrylate (UMM) as one kind of functional filler has played an important role in reinforcing rubber materials. The in situ self-polymerization of UMM in UMM/rubber composite leads to the uniform dispersion of poly(UMM) in the rubber matrix, while the crosslinking of rubber and grafting between UMM and rubber chains occur simultaneously, making it difficult to clarify the effect of the in situ polymerization on the dispersion of poly(UMM) in the rubber matrix. In this work, we investigated the dispersion mechanism of UMM without rubber matrix for the first time using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. Three types of UMMs including zinc methacrylate (Zn(MA){sub 2}), sodium methacrylate (Na(MA)) and samarium methacrylate (Sm(MA){sub 3}) were chosen to investigate the in situ self-polymerization of UMM. Based on DSC results, we conclude that the crystals with low melting point tend to self-polymerize first and generate a large amount of heat in the presence of peroxide. The high heat of reaction can melt the crystals with high melting point, and more UMM molecules are dissolved in the rubber matrix, thus increasing the extent of the in situ polymerization. Hence, the UMM with low melting point can self-polymerize to a large extent. Our findings provide in-depth understanding of the dispersion mechanism of UMM in rubber.

  14. In situ self-polymerization of unsaturated metal methacrylate and its dispersion mechanism in rubber-based composites

    International Nuclear Information System (INIS)

    Wen, Shipeng; Zhou, Yao; Yao, Lu; Zhang, Liqun; Chan, Tung W.; Liang, Yongri; Liu, Li

    2013-01-01

    Highlights: • In situ self-polymerization of unsaturated metal methacrylate was investigated mainly by the thermal effect. • UMM with low melting point can self-polymerize to a large extent. • The fine dispersion phase is composed of poly(UMM) nanoparticles formed by in situ self-polymerization in the rubber matrix. • The UMM crystals in the presence of peroxide and rubber undergo the processes of melting, diffusion, polymerization, and phase separation in this order. - Abstract: Unsaturated metal methacrylate (UMM) as one kind of functional filler has played an important role in reinforcing rubber materials. The in situ self-polymerization of UMM in UMM/rubber composite leads to the uniform dispersion of poly(UMM) in the rubber matrix, while the crosslinking of rubber and grafting between UMM and rubber chains occur simultaneously, making it difficult to clarify the effect of the in situ polymerization on the dispersion of poly(UMM) in the rubber matrix. In this work, we investigated the dispersion mechanism of UMM without rubber matrix for the first time using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. Three types of UMMs including zinc methacrylate (Zn(MA) 2 ), sodium methacrylate (Na(MA)) and samarium methacrylate (Sm(MA) 3 ) were chosen to investigate the in situ self-polymerization of UMM. Based on DSC results, we conclude that the crystals with low melting point tend to self-polymerize first and generate a large amount of heat in the presence of peroxide. The high heat of reaction can melt the crystals with high melting point, and more UMM molecules are dissolved in the rubber matrix, thus increasing the extent of the in situ polymerization. Hence, the UMM with low melting point can self-polymerize to a large extent. Our findings provide in-depth understanding of the dispersion mechanism of UMM in rubber

  15. Microstructure and tribological properties of NiMo/Mo2Ni3Si intermetallic 'in-situ' composites

    International Nuclear Information System (INIS)

    Gui Yongliang; Song Chunyan; Yang Li; Qin Xiaoling

    2011-01-01

    Research highlights: → Wear resistant NiMo/Mo 2 Ni 3 Si intermetallic 'in-situ' composites was fabricated successfully with Mo-Ni-Si powder blends as the starting materials. Microstructure of the NiMo/Mo 2 Ni 3 Si composites consists of Mo 2 Ni 3 Si primary dendrites, binary intermetallic phase NiMo and small amount of Ni/NiMo eutectics structure. The NiMo/Mo 2 Ni 3 Si composites exhibited high hardness and outstanding tribological properties under room-temperature dry-sliding wear test conditions which were attributed to the covalent-dominant strong atomic bonds and excellent combination of strength and ductility and toughness. - Abstract: Wear resistant NiMo/Mo 2 Ni 3 Si intermetallic 'in-situ' composites with a microstructure of ternary metal silicide Mo 2 Ni 3 Si primary dendritic, the long strip-like NiMo intermetallic phase, and a small amount of Ni/NiMo eutectics structure were designed and fabricated using molybdenum, nickel and silicon elemental powders. Friction and wear properties of NiMo/Mo 2 Ni 3 Si composites were evaluated under different contact load at room-temperature dry-sliding wear test conditions. Microstructure, worn surface morphologies and subsurface microstructure were characterized by OM, XRD, SEM and EDS. Results indicate that NiMo/Mo 2 Ni 3 Si composites have low fiction coefficient, excellent wear resistance and sluggish wear-load dependence. The dominant wear mechanisms of NiMo/Mo 2 Ni 3 Si composites are soft abrasion and slightly superficial oxidative wear.

  16. Layer by Layer Ex-Situ Deposited Cobalt-Manganese Oxide as Composite Electrode Material for Electrochemical Capacitor.

    Science.gov (United States)

    Rusi; Chan, P Y; Majid, S R

    2015-01-01

    The composite metal oxide electrode films were fabricated using ex situ electrodeposition method with further heating treatment at 300°C. The obtained composite metal oxide film had a spherical structure with mass loading from 0.13 to 0.21 mg cm(-2). The structure and elements of the composite was investigated using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). The electrochemical performance of different composite metal oxides was studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (CD). As an active electrode material for a supercapacitor, the Co-Mn composite electrode exhibits a specific capacitance of 285 Fg(-1) at current density of 1.85 Ag(-1) in 0.5 M Na2SO4 electrolyte. The best composite electrode, Co-Mn electrode was then further studied in various electrolytes (i.e., 0.5 M KOH and 0.5 M KOH/0.04 M K3Fe(CN) 6 electrolytes). The pseudocapacitive nature of the material of Co-Mn lead to a high specific capacitance of 2.2 x 10(3) Fg(-1) and an energy density of 309 Whkg(-1) in a 0.5 M KOH/0.04 M K3Fe(CN) 6 electrolyte at a current density of 10 Ag(-1). The specific capacitance retention obtained 67% of its initial value after 750 cycles. The results indicate that the ex situ deposited composite metal oxide nanoparticles have promising potential in future practical applications.

  17. Unusual tensile behaviour of fibre-reinforced indium matrix composite and its in-situ TEM straining observation

    International Nuclear Information System (INIS)

    Luo, Xin; Peng, Jianchao; Zandén, Carl; Yang, Yanping; Mu, Wei; Edwards, Michael; Ye, Lilei; Liu, Johan

    2016-01-01

    Indium-based thermal interface materials are superior in thermal management applications of electronic packaging compared to their polymer-based counterparts. However, pure indium has rather low tensile strength resulting in poor reliability. To enhance the mechanical properties of such a material, a new composite consisting of electrospun randomly oriented continuous polyimide fibres and indium was fabricated. The composite has been characterised by tensile tests and in-situ transmission electron microscopy straining observations. It is shown that the composite's ultimate tensile strength at 20 °C is five times higher than that of pure indium, and the strength of the composite exceeds the summation of strengths of the individual components. Furthermore, contrary to most metallic matrix materials, the ultimate tensile strength of the composite decreases with the increased strain rate in a certain range. The chemical composition and tensile fracture of the novel composite have been analysed comprehensively by means of scanning transmission electron microscopy and scanning electron microscopy. A strengthening mechanism based on mutually reinforcing structures formed by the indium and surrounding fibres is also presented, underlining the effect of compressing at the fibre/indium interfaces by dislocation pileups and slip pinning.

  18. Oxidation protection and behavior of in-situ zirconium diboride–silicon carbide coating for carbon/carbon composites

    International Nuclear Information System (INIS)

    Li, Lu; Li, Hejun; Yin, Xuemin; Chu, Yanhui; Chen, Xi; Fu, Qiangang

    2015-01-01

    Highlights: • ZrB 2 –SiC coating was prepared on C/C composite by in-situ reaction. • A two-layered structure was obtained when the coating was oxidized at 1500 °C. • The formation and collapse of bubbles influenced the coating oxidation greatly. • The morphology evolution of oxide scale during oxidation was illuminated. - Abstract: To protect carbon/carbon (C/C) composites against oxidation, zirconium diboride–silicon carbide (ZrB 2 –SiC) coating was prepared by in-situ reaction using ZrC, B 4 C and Si as raw materials. The in-situ ZrB 2 –SiC coated C/C presented good oxidation resistance, whose weight loss was only 0.15% after isothermal oxidation at 1500 °C for 216 h. Microstructure evolution of coating at 1500 °C was studied, revealing a two-layered structure: (1) ZrO 2 (ZrSiO 4 ) embedded in SiO 2 -rich glass, and (2) unaffected ZrB 2 –SiC. The formation and collapse of bubbles influenced the coating oxidation greatly. A model based on the evolution of oxide scale was proposed to explain the failure mechanism of coating

  19. Mn{sub 2}O{sub 3}/carbon aerogel microbead composites synthesized by in situ coating method for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xingyan, E-mail: wxianyou@yahoo.com [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Chemistry School, Xiangtan University, Hunan, Xiangtan 411105 (China); Hunan Institute of Humanities Science and Technology, Loudi 417000 (China); Key Laboratory of Materials Design and Preparation Technology of Hunan, Xiangtan 411105 (China); Liu Li [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Chemistry School, Xiangtan University, Hunan, Xiangtan 411105 (China); Wang Xianyou, E-mail: wqinyan801@yahoo.com.cn [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Chemistry School, Xiangtan University, Hunan, Xiangtan 411105 (China); Key Laboratory of Materials Design and Preparation Technology of Hunan, Xiangtan 411105 (China); Yi Lanhua [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Chemistry School, Xiangtan University, Hunan, Xiangtan 411105 (China); Hu Chuanyue [Hunan Institute of Humanities Science and Technology, Loudi 417000 (China); Zhang Xiaoyan [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Chemistry School, Xiangtan University, Hunan, Xiangtan 411105 (China)

    2011-09-15

    Highlights: > Mn{sub 2}O{sub 3}/CAMB composite materials for supercapacitor were prepared by in situ coating method. > The optimum amount of Mn{sub 2}O{sub 3} in Mn{sub 2}O{sub 3}/CAMB composite is 10 wt%. > Coating nano-sized Mn{sub 2}O{sub 3} on the CAMB could improve the supercapacitive behaviors of composites. - Abstract: A series of Mn{sub 2}O{sub 3}/carbon aerogel microbead (Mn{sub 2}O{sub 3}/CAMB) composites for supercapacitor electrodes have been synthesized by in situ encapsulation method. The structure and morphology of Mn{sub 2}O{sub 3}/CAMB are characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrum and scanning electron microscopy (SEM). Electrochemical performances of the synthesized composites are evaluated by cyclic voltammetry and galvanostatic charge/discharge measurement. All the composites with different Mn{sub 2}O{sub 3} contents show higher specific capacitance than pure CAMB due to the pseudo-capacitance of the Mn{sub 2}O{sub 3} particles dispersed on the surface of CAMB. The highest specific capacitance is up to 368.01 F g{sup -1} when 10 wt% Mn{sub 2}O{sub 3} is coated on the surface of CAMB. Besides, 10%-Mn{sub 2}O{sub 3}/CAMB supercapacitor exhibits excellent cyclic stability, the specific capacitance still retains 90% of initial capacitance over 5000 cycles.

  20. Processing and Mechanical Properties of NiAl-Based In-Situ Composites. Ph.D. Thesis Final Report

    Science.gov (United States)

    Johnson, David Ray

    1994-01-01

    In-situ composites based on the NiAl-Cr eutectic system were successfully produced by containerless processing and evaluated. The NiAl-Cr alloys had a fibrous microstructure while the NiAl-(Cr,Mo) alloys containing 1 at. percent or more molybdenum exhibited a lamellar structure. The NiAl-28Cr-6Mo eutectic displays promising high temperature strength while still maintaining a reasonable room temperature fracture toughness when compared to other NiAl-based materials. The Laves phase NiAlTa was used to strengthen NiAl and very promising creep strengths were found for the directionally solidified NiAl-NiAlTa eutectic. The eutectic composition was found to be near NiAl-15.5Ta (at. percent) and well aligned microstructures were produced at this composition. An off-eutectic composition of NiAl-14.5Ta was also processed, consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of these two phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Polyphase in-situ composites were generated by directional solidification of ternary eutectics. The systems investigated were the Ni-Al-Ta-X (X=Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and both the eutectic composition and temperature were determined. Of these ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr,Al)NiTa-Cr eutectic was intermediate between those of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

  1. The crack propagating behavior of composite coatings prepared by PEO on aluminized steel during in situ tensile processing

    International Nuclear Information System (INIS)

    Chen Zhitong; Li Guang; Wu Zhenqiang; Xia Yuan

    2011-01-01

    Research highlights: → Composite coatings on the aluminized steel were prepared by the plasma electrolytic oxidation (PEO) technique, which comprised of Fe-Al layer, Al layer and Al 2 O 3 layer. → The evaluation method of the crack critical opening displacement δ c was introduced to describe quantitatively the resistance of Al layer to the propagation behavior of cracks and evaluate the fracture behavior of composite coatings. → The crack propagating model was established. - Abstract: This paper investigates the in situ tensile cracks propagating behavior of composite coatings on the aluminized steel generated using the plasma electrolytic oxidation (PEO) technique. Cross-sectional micrographs and elemental compositions were investigated by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The composite coatings were shown to consist of Fe-Al, Al and Al 2 O 3 layers. The cracks propagating behavior was observed in real-time in situ SEM tensile test. In tensile process, the cracks were temporarily stopped when cracks propagated from Fe-Al layer to Al layer. The critical crack opening displacement δ c was introduced to quantitatively describe the resistance of the Al layer. There was a functional relation among the thickness ratio t Al /t Al 2 O 3 , the δ c of composite coatings and tensile cracks' spacing. The δ c increased with the increasing of the thickness ratio (t Al /t Al 2 O 3 ). The high δ c value means high fracture resistance. Therefore, a control of the thickness ratio t Al /t Al 2 O 3 was concerned as a key to improve the toughness and strength of the aluminized steel.

  2. Laser-activated protein solder for peripheral nerve repair

    Science.gov (United States)

    Trickett, Rodney I.; Lauto, Antonio; Dawes, Judith M.; Owen, Earl R.

    1995-05-01

    A 100 micrometers core optical fiber-coupled 75 mW diode laser operating at a wavelength of 800 nm has been used in conjunction with a protein solder to stripe weld severed rat tibial nerves, reducing the long operating time required for microsurgical nerve repair. Welding is produced by selective laser denaturation of the albumin based solder which contains the dye indocyanine green. Operating time for laser soldering was 10 +/- 5 min. (n equals 20) compared to 23 +/- 9 min. (n equals 10) for microsuturing. The laser solder technique resulted in patent welds with a tensile strength of 15 +/- 5 g, while microsutured nerves had a tensile strength of 40 +/- 10 g. Histopathology of the laser soldered nerves, conducted immediately after surgery, displayed solder adhesion to the outer membrane with minimal damage to the inner axons of the nerves. An in vivo study is under way comparing laser solder repaired tibial nerves to conventional microsuture repair. At the time of submission 15 laser soldered nerves and 7 sutured nerves were characterized at 3 months and showed successful regeneration with compound muscle action potentials of 27 +/- 8 mV and 29 +/- 8 mW respectively. A faster, less damaging and long lasting laser based anastomotic technique is presented.

  3. In-situ Observation of Fracture Behavior on Nano Structure in NITE SiC/SiC Composite by HVEM

    International Nuclear Information System (INIS)

    Shibayama, Tamaki; Hamada, Kouichi; Watanabe, Seiichi; Matsuo, Genichiro; Kishimoto, Hirotatsu

    2011-01-01

    We have been successfully done in situ observation on the sequence of fracture event at the interface of NITE SiC/SiC composite examined by using miniaturized double notched shear specimen for TEM prepared by Focused Ion Beam method. In this study, we used nano-mechanics TEM experimental apparatus to investigate not only microstructure evolution and but also load and displacement curve at once in High Voltage Electron Microscope. Our results summarize as follows. Cracks were initiated at the interface between carbon coating layer on the SiC fiber and SiC matrices, and propagated along the interface. Load drop in the load and displacement curve during in-situ TEM was clearly observed at the crack initiation. The shear strength by using the miniaturized specimen is about ten times higher than that obtained by the standard testing.

  4. In-situ deformation studies of an aluminum metal-matrix composite in a scanning electron microscope

    Science.gov (United States)

    Manoharan, M.; Lewandowski, J. J.

    1989-01-01

    Tensile specimens made of a metal-matrix composite (cast and extruded aluminum alloy-based matrix reinforced with Al2O3 particulate) were tested in situ in a scanning electron microscope equipped with a deformation stage, to directly monitor the crack propagation phenomenon. The in situ SEM observations revealed the presence of microcracks both ahead of and near the crack-tip region. The microcracks were primarily associated with cracks in the alumina particles. The results suggest that a region of intense deformation exists ahead of the crack and corresponds to the region of microcracking. As the crack progresses, a region of plastically deformed material and associated microcracks remains in the wake of the crack.

  5. Numerical prediction of mechanical properties of Pb-Sn solder alloys containing antimony, bismuth and or silver ternary trace elements

    Science.gov (United States)

    Gadag, Shiva P.; Patra, Susant

    2000-12-01

    Solder joint interconnects are mechanical means of structural support for bridging the various electronic components and providing electrical contacts and a thermal path for heat dissipation. The functionality of the electronic device often relies on the structural integrity of the solder. The dimensional stability of solder joints is numerically predicted based on their mechanical properties. Algorithms to model the kinetics of dissolution and subsequent growth of intermetallic from the complete knowledge of a single history of time-temperature-reflow profile, by considering equivalent isothermal time intervals, have been developed. The information for dissolution is derived during the heating cycle of reflow and for the growth process from cooling curve of reflow profile. A simple and quick analysis tool to derive tensile stress-strain maps as a function of the reflow temperature of solder and strain rate has been developed by numerical program. The tensile properties are used in modeling thermal strain, thermal fatigue and to predict the overall fatigue life of solder joints. The numerical analysis of the tensile properties as affected by their composition and rate of testing, has been compiled in this paper. A numerical model using constitutive equation has been developed to evaluate the interfacial fatigue crack growth rate. The model can assess the effect of cooling rate, which depends on the level of strain energy release rate. Increasing cooling rate from normalizing to water-quenching, enhanced the fatigue resistance to interfacial crack growth by up to 50% at low strain energy release rate. The increased cooling rates enhanced the fatigue crack growth resistance by surface roughening at the interface of solder joint. This paper highlights salient features of process modeling. Interfacial intermetallic microstructure is affected by cooling rate and thereby affects the mechanical properties.

  6. Interconnection of thermal parameters, microstructure and mechanical properties in directionally solidified Sn–Sb lead-free solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Marcelino; Costa, Thiago [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil); Rocha, Otávio [Federal Institute of Education, Science and Technology of Pará — IFPA, 66093-020 Belém, PA (Brazil); Spinelli, José E. [Department of Materials Engineering, Federal University of São Carlos — UFSCar, 13565-905 São Carlos, SP (Brazil); Cheung, Noé, E-mail: cheung@fem.unicamp.br [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil); Garcia, Amauri [Department of Manufacturing and Materials Engineering, University of Campinas — UNICAMP, 13083-860 Campinas, SP (Brazil)

    2015-08-15

    Considerable effort is being made to develop lead-free solders for assembling in environmental-conscious electronics, due to the inherent toxicity of Pb. The search for substitute alloys of Pb–Sn solders has increased in order to comply with different soldering purposes. The solder must not only meet the expected levels of electrical performance but may also have appropriate mechanical strength, with the absence of cracks in the solder joints. The Sn–Sb alloy system has a range of compositions that can be potentially included in the class of high temperature solders. This study aims to establish interrelations of solidification thermal parameters, microstructure and mechanical properties of Sn–Sb alloys (2 wt.%Sb and 5.5 wt.%Sb) samples, which were directionally solidified under cooling rates similar to those of reflow procedures in industrial practice. A complete high-cooling rate cellular growth is shown to be associated with the Sn–2.0 wt.%Sb alloy and a reverse dendrite-to-cell transition is observed for the Sn–5.5 wt.%Sb alloy. Strength and ductility of the Sn–2.0 wt.%Sb alloy are shown not to be affected by the cellular spacing. On the other hand, a considerable variation in these properties is associated with the cellular region of the Sn–5.5 wt.%Sb alloy casting. - Graphical abstract: Display Omitted - Highlights: • The microstructure of the Sn–2 wt.%Sb alloy is characterized by high-cooling rates cells. • Reverse dendrite > cell transition occurs for Sn–5.5 wt.%Sb alloy: cells prevail for cooling rates > 1.2 K/s. • Sn–5.5 wt.%Sb alloy: the dendritic region occurs for cooling rates < 0.9 K/s. • Sn–5.5 wt.%Sb alloy: tensile properties are improved with decreasing cellular spacing.

  7. Reinforcement of nylon 6,6/nylon 6,6 grafted nanodiamond composites by in situ reactive extrusion

    Science.gov (United States)

    Choi, Eun-Yeob; Kim, Kiho; Kim, Chang-Keun; Kang, Eunah

    2016-11-01

    Nanodiamond (ND), an emerging new carbon material, was exploited to reinforce nylon 6,6 (PA66) polymer composites. Surface modified nanodiamonds with acyl chloride end groups were employed to chemically graft into PA66, enhancing the interfacial adhesion and thus the mechanical properties. The ND grafted PA66 (PA66-g-ND) reinforced PA66 composite prepared by in situ reactive extrusion exhibited increased tensile strength and modulus. The tensile strength and modulus of PA66/3 wt.% PA66-g-ND composites were enhanced by 11.6 and 20.8%, respectively when compared to those of the bare PA66 matrix. Even the PA66/pristine ND composites exhibited enhanced mechanical properties. The PA66-g-ND and the homogeneously dispersed PA66-g-ND in PA66 matrix were examined using X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy techniques. The mechanical properties and thermal conductivities of the nanodiamond incorporated PA66 composites were also explored. The enhanced mechanical properties and thermal conductivities of the PA66-g-ND/PA66 composites make them potential materials for new applications as functional engineered thermoplastics.

  8. Effect of Rare Earth Element on Microstructure and Properties of in situ Synthesized TiB2/Al Composites

    Directory of Open Access Journals (Sweden)

    QU Min

    2018-03-01

    Full Text Available The effect of rare earth element Ce, Sc and Er on TiB2 particles and matrix alloy micros-tructure of TiB2/Al composites was studied with in situ synthesis method. It shows that the addition of rare earth element improves the microstructure and properties of TiB2/Al composites notably. The particles of TiB2 are relatively homogenously distributed as adding 0.3% (mass fraction rare earth element Sc and Er, moreover, it is Er that refines the microstructure of matrix alloy most significantly, then is Sc. Similarly, it is demonstrated that the addition of Sc and Er results in better tensile strength, which is enhanced by 32% and 31%, respectively; the addition of Er also leads to the best ductility by 85% with optimal tensile property. Meanwhile, fracture morphology analysis reveals that the fracture of the composites is microporous gathered ductile fracture when adding Sc and Er. Finally, it is verified that the mechanism of rare earth element on composites lies in two aspects:one is that the addition of rare earth element improves the wettability of the composites and suppresses the agglomeration of TiB2 particles; the other is that the addition of rare earth element refines the microstructure of matrix alloy and then improves the tensile strength of the composites.

  9. Paloma: In-Situ Measurement of the Isotopic Composition of Mars Atmosphere

    Science.gov (United States)

    Jambon, A.; Quemerais, E.; Chassiefiere, E.; Berthelier, J. J.; Agrinier, P.; Cartigny, P.; Javoy, M.; Moreira, M.; Sabroux, J. -C.; Sarda, P.; Pineau, J. -F.

    2000-07-01

    Scientific objectives for an atmospheric analysis of Mars are presented in the DREAM project. Among the information presently available most are fragmentary or limited in their precision for both major element (H, C, O, N) and noble gas isotopes. These data are necessary for the understanding and modelling of Mars atmospheric formation and evolution, and consequently for other planets, particularly the Earth. To fulfill the above requirements, two approaches can be envisonned: 1) analysis of a returned sample (DREAM project) or 2) in situ analysis, e.g. PALOMA project presented here. Among the advantages of in situ analysis, we notice: the minimal terrestrial contamination, the unlimited availability of gas to be analyzed and the possibility of multiple analyses (replicates, daynight... ). Difficulties specific to in situ analyses are of a very different kind to those of returned samples. In situ analysis could also be viewed as a preparation to future analysis of returned samples. Finally, some of the measurements will not be possible on Earth: for instance, radon and its short lived decay products, will provide complementary information to 4-He analysis and can only be obtained in situ, independently of analytical capabilities.

  10. Micromechanics of deformation of metallic-glass-matrix composites from in situ synchrotron strain measurements and finite element modeling

    International Nuclear Information System (INIS)

    Ott, R.T.; Sansoz, F.; Molinari, J.F.; Almer, J.; Ramesh, K.T.; Hufunagel, T.C.

    2005-01-01

    In situ X-ray scattering and finite element modeling (FEM) were used to examine the micromechanics of deformation of in situ formed metallic-glass-matrix composites consisting of Ta-rich particles dispersed in an amorphous matrix. The strain measurements show that under uniaxial compression the second-phase particles yield at an applied stress of approx. 325 MPa. After yielding, the particles do not strain harden significantly; we show that this is due to an increasingly hydrostatic stress state arising from the lateral constraint on deformation of the particles imposed by the elastic matrix. Shear band initiation in the matrix is not due to the difference in elastic properties between the matrix and the particles. Rather, the development of a plastic misfit strain causes stress concentrations around the particles, resulting in localized yielding of the matrix by shear band formation at an applied stress of approx. 1450 MPa, considerably lower than the macroscopic yield stress of the composite (approx. 1725 MPa). Shear bands do not propagate at the lower stress because the yield criterion of the matrix is only satisfied in the region immediately around the particles. At the higher stresses, the yield criterion is satisfied in large regions of the matrix, allowing extensive shear band propagation and significant macroscopic plastic deformation. However, the presence of the particles makes the stress state highly inhomogeneous, which may partially explain why fracture is suppressed in the composite, allowing the development of large plastic strains

  11. Microstructure and mechanical properties of in situ casting TiC/Ti6Al4V composites through adding multi-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Ya, Bin; Zhou, Bingwen; Yang, Hongshuo; Huang, Bingkun; Jia, Fei; Zhang, Xingguo, E-mail: zxgwj@dlut.edu.cn

    2015-07-15

    Highlights: • Adding MWCNTs in situ casting fabricating TiC/Ti6Al4V composites is first reported. • The solidification process of in situ casting TiC/Ti6Al4V composites is discussed. • Microstructure shows remarkable correlations with adding MWCNTS. • Strength and plasticity show remarkable correlations with adding MWCNTs. - Abstract: In this study, multi-walled carbon nanotubes (MWCNTs) were added as carbon sources to fabricate in situ casting TiC/Ti6Al4V (TC4) composites. The effects of MWCNTs on the microstructure and mechanical properties are studied. The composites are analyzed by X-ray diffraction, field-emission scanning electron microscope and electron probe microanalysis. The fracture behavior of TiC/TC4 composites are also studied. Smaller size of TiC particles and grain compared with TC4-graphite composites can be observed. The tensile strength of TC4-MWCNTs composites is about 1110.1 MPa, which is higher than that of TC4-graphite composites, about 1003.6 MPa. Fracture behavior also was changed by adding MWCNTs in situ casting TiC/TC4 composites.

  12. Integration of environmentally compatible soldering technologies for waste minimization

    International Nuclear Information System (INIS)

    Hosking, F.M.

    1992-01-01

    There has been a concentrated effort throughout the international microelectronics industry to phase out chlorofluorocarbon (CFC) materials and alleviate the serious problem of ozone depletion created by the release of CFCS. The development of more environmentally compatible manufacturing technologies is the cornerstone of this effort. Alternative materials and processes for cleaning and soldering have received special attention. Electronic. soldering typically utilizes rosin-based fluxes to promote solder wettability. Flux residues must be removed from the soldered parts when high product reliability is essential. Halogenated or CFC solvents have been the principle chemicals used to clean the residues. With the accelerated push to eliminate CFCs in the US by 1995, CFC-free solvents, aqueous-based cleaning, water soluble or ''no clean'' fluxes, and fluxless soldering technologies are being developed and quickly integrated into manufacturing practice. Sandia's Center for Solder Science and Technology has been ch g a variety of fluxless and alternative soldering technologies for DOE's waste minimization program. The work has focused on controlled atmosphere, laser, and ultrasonic fluxless soldering, protective metallic and organic coatings, and fluxes which have water soluble or low solids-based chemistries. With the increasing concern that Pb will also be banned from electronic soldering, Sandia has been characterizing the wetting, aging, and mechanical properties of Pb-fire solder alloys. The progress of these integrated studies will be discussed. Their impact on environmentally compatible manufacturing will be emphasized. Since there is no universal solution to the various environmental, safety, and health issues which currently face industry, the proposed technologies offer several complementary materials and processing options from which one can choose

  13. Microstructurally Adaptive Constitutive Relations and Reliability Assessment Protocols for Lead Free Solder

    Science.gov (United States)

    2015-05-05

    under bump metallurgy and solder joint geometry on Sn grain morphology in Pb free solder joints were examined. SnAgCu solder joints were examined for...free solder interconnects”, Sci. Technol. Weld . Join. 13, 732 (2008). [3.25] Terashima, S., Takahama, K., Nozaki, M., and Tanaka, M. Recrystallization

  14. In situ synthesis of α-MoO3/graphene composites as anode materials for lithium ion battery

    International Nuclear Information System (INIS)

    Liu, Chun-Ling; Wang, Yan; Zhang, Chen; Li, Xiao-Shan; Dong, Wen-Sheng

    2014-01-01

    The α-MoO 3 /graphene composites (MoO 3 /G) were prepared via an in situ hydrothermal synthesis. The composites were characterized using various characterization techniques including powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and the electrochemical performance test. The results show that these MoO 3 /G composites exhibit high capacity and good cycle stability when used as the lithium-ion battery anode. Among all the samples, the MoO 3 /G-27 reveals the best electrochemical performance with an initial charge capacity of 977.7 mAh g −1 at a current density of 50 mA g −1 , the first coulombic efficiency of 69.5%. After eighty cycles the electrode still maintains a capacity of 869.2 mAh g −1 , giving high capacity retention of 88.9%. The good electrochemical performance of the composite anode is close related to its structure, in which the MoO 3 nanobelts are not only homogeneously anchored on the surface but also embedded in the interlayer of the graphene sheets; hence the volume change and aggregation of the MoO 3 nanobelts during lithium ion insertion/extraction process can be effectively hindered. On the other hand, graphene itself is an electronic conductor; the graphene and MoO 3 nanobelts connect closely, which offers large electrode/electrolyte contacting area, short path length for Li + transporting during lithium insertion and extraction. - Highlights: • The α-MoO 3 /graphene composites were prepared via an in situ hydrothermal synthesis. • The MoO 3 /G-27 anode delivers an initial reversible capacity of 977.7 mAh g −1 . • After 80 cycles it has a reversible capacity of 869.2 mAh g −1 at 50 mA g −1

  15. Superior electrode performance of LiFePO4/C composite prepared by an in situ polymerization restriction method

    International Nuclear Information System (INIS)

    Chen, Jian; Zou, Yong-Cun; Zhang, Feng; Zhang, Yuan-Chun; Guo, Fei-Fan; Li, Guo-Dong

    2013-01-01

    Highlights: ► LiFePO 4 /C composite was prepared by an in situ polymerization restriction method. ► The size of LiFePO 4 in the composite is effectively restricted. ► The high-rate capability and cycling performance of LiFePO 4 are enhanced greatly. -- Abstract: The LiFePO 4 /C composite is prepared by heating the mixture of resorcinol–formaldehyde gel and FePO 4 , synthesized by an in situ polymerization restriction method, and lithium acetate dihydrate in the atmosphere of nitrogen. The physical and electrochemical properties of the LiFePO 4 /C composite are investigated by X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy and electrochemical measurements. The discharge capacity of LiFePO 4 is as high as 155.6 mA h g −1 in the first cycle at 0.5C, and it could remain 144.0 mA h g −1 after 50 cycles. Even at the high rates of 10C, 20C and 50C, the initial discharge capacities of the electrodes exhibit 115.6 mA h g −1 , 84.5 mA h g −1 and 67.8 mA h g −1 , and the electrodes deliver capacity retention of 89.5%, 90.9% and 85.7% after 1000 cycles, respectively. The outstanding electrochemical performance could be attributed to the small particle size and good electronic conductivity of the composite

  16. In situ intercalative polymerization of poly (ε-caprolactone)/ 12-amino lauric acid-modified clay nano composites

    International Nuclear Information System (INIS)

    Reyes, Larry; Monserate, Juvy J.; Sumera, Florentino

    2013-01-01

    Polymer/layered silicate nano composites were prepared by in situ intercalative polymerization method from from ε-caprolactone (ε-CL) and 12-amino lauric acid modified montmorillonite (AMMT). The organo-modified clay was investigated for its capacity to facilitate ring-opening polymerization of ε-caprolactone within its silicate layers. The effect of varying the organo-modified clay loading (5%, 10% and 15% by weight) on the molecular weight of the poly (ε-caprolactone) (PCL) product was assessed by gel-permeation chromatography. The molecular weight of the polymer with different clay loadings ranged from ∼30,000 g/mo to ∼70,000 g/mol, where the 10% loading produced the highest molecular weight. Fourier Transform infrared (FTIR), and 1 H and 13 C Nuclear Magnetic Resonance (NMR) Spectroscopy were conducted to probe the composition of the polymer and the catalytic activity of AMMT to polymerize ε-CL. FTIR analyses showed two medium intensity and narrow CO-O stretching vibrations for the PCL products at around 1240 cm-1 and 1160 cm-1, which are attributed to ester skeletal backbone. 1 HNMR spectroscopic analysis revealed signals at 4.07 ppm and 3.66 ppm which can be attributed to εmethylene of caprolactone and methyl of ending ester group, respectively. The formation of the nano composites were assessed by X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM), XRD analyses showed a broadening and disappearance of diffraction peak of AMMT in the nana composite which may indicate the formation of the intercalated and partially exfoliated PCVL/AMMT nana composites. TEM observations corroborated the presence of intercalated and exfoliated layers of AMMT after polymerization. The present work demonstrates that AMMT can be used as an alternative g reen catalyst's for the production of biodegradable polymers, where the in situ intercalative polymerization was employed as a direct method of preparing polymer/layered silicates (author)

  17. Study of the morphology exhibited by exfoliated polyurethane/montmorillonite nano composites during in situ recovery tests

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Iaci M., E-mail: iaci@ctex.eb.br [Divisao Belica do Centro Tecnologico do Exercito. CTEx, Rio de Janeiro, RJ (Brazil); Orefice, Rodrigo L. [Universidade Federal de Minas Gerais Departamento de Metalurgia e Materiais. UFMG, Belo Horizonte, MG (Brazil)

    2011-07-01

    By using small-angle X-ray scattering, this study aims to examine the SM behavior of montmorillonite polyurethane nano composites. To investigate the phase morphology, a deformed specimen was placed on a heating stage mounted at the Synchrotron beamline; the shape recovery was measured during 15 min. As temperature increases, the crystalline fraction rapidly decreases. The degree of clay delamination within the matrix increases, disturbing the formation of hard and soft segments. Deformation induces changes in the phase proportion, increasing the disperse phase contribution. During in situ tests, the ratio between matrix and disperse phase reaches an equilibrium controlled by the temperature. (author)

  18. Laser cladding in-situ carbide particle reinforced Fe-based composite coatings with rare earth oxide addition

    Institute of Scientific and Technical Information of China (English)

    吴朝锋; 马明星; 刘文今; 钟敏霖; 张红军; 张伟明

    2009-01-01

    Particulate reinforced metal matrix composite(PR-MMC) has excellent properties such as good wear resistance,corrosion resistance and high temperature properties.Laser cladding is usually used to form PR-MMC on metal surface with various volume fractions of ceramic particles.Recent literatures showed that laser melting of powder mixture containing carbon and carbide-forming elements,was favorable for the formation of in-situ synthesized carbide particles.In this paper,rare earth oxide(RE2O3) was added into t...

  19. Monitoring of the microbial community composition of the saline aquifers during CO2 storage by fluorescence in situ hybridisation

    OpenAIRE

    Daria Morozova; M. Wandrey; Mashal Alawi; Martin Zimmer; Andrea Vieth-Hillebrand [Vieth; M. Zettlitzer; Hilke Würdemann

    2010-01-01

    This study reveals the first analyses of the composition and activity of the microbial community of a saline CO2 storage aquifer. Microbial monitoring during CO2 injection has been reported. By using fluorescence in situ hybridisation (FISH), we have shown that the microbial community was strongly influenced by the CO2 injection. Before CO2 arrival, up to 6 × 106 cells ml−1 were detected by DAPI staining at a depth of 647 m below the surface. The microbial community was dominated by the dom...

  20. Addendum to: Derivation of in situ opalinus clay porewater compositions from experimental and geochemical modelling studies

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens; Pearson, F.J.; Berner, U.

    1998-01-01

    As part of the synthesis of water chemistry studies within the hydrochemical program at Mont Terri (Switzerland), a reexamination of the modelling method showed that it should lead to a range of water compositions rather than to a single composition. The single composition resulted from two compensating oversights, a theoretical one and a modelling one. These are discussed in this Addendum. (author)

  1. Microstructure and property evolutions of titanium/nano-hydroxyapatite composites in-situ prepared by selective laser melting.

    Science.gov (United States)

    Han, Changjun; Wang, Qian; Song, Bo; Li, Wei; Wei, Qingsong; Wen, Shifeng; Liu, Jie; Shi, Yusheng

    2017-07-01

    Titanium (Ti)-hydroxyapatite (HA) composites have the potential for orthopedic applications due to their favorable mechanical properties, excellent biocompatibility and bioactivity. In this work, the pure Ti and nano-scale HA (Ti-nHA) composites were in-situ prepared by selective laser melting (SLM) for the first time. The phase, microstructure, surface characteristic and mechanical properties of the SLM-processed Ti-nHA composites were studied by X-ray diffraction, transmission electron microscope, atomic force microscope and tensile tests, respectively. Results show that SLM is a suitable method for fabricating the Ti-nHA composites with refined microstructure, low modulus and high strength. A novel microstructure evolution can be illustrated as: Relatively long lath-shaped grains of pure Ti evolved into short acicular-shaped and quasi-continuous circle-shaped grains with the varying contents of nHA. The elastic modulus of the Ti-nHA composites is 3.7% higher than that of pure Ti due to the effect of grain refinement. With the addition of 2% nHA, the ultimate tensile strength significantly reduces to 289MPa but still meets the application requirement of bone implants. The Ti-nHA composites exhibit a remarkable improvement of microhardness from 336.2 to 600.8 HV and nanohardness from 5.6 to 8.3GPa, compared to those of pure Ti. Moreover, the microstructure and property evolution mechanisms of the composites with the addition of HA were discussed and analyzed. It provides some new knowledge to the design and fabrication of biomedical material composites for bone implant applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Characterization of lead-free solders for electronic packaging

    Science.gov (United States)

    Ma, Hongtao

    The characterization of lead-free solders, especially after isothermal aging, is very important in order to accurately predict the reliability of solder joints. However, due to lack of experimental testing standards and the high homologous temperature of solder alloys (Th > 0.5T m even at room temperature), there are very large discrepancies in both the tensile and creep properties provided in current databases for both lead-free and Sn-Pb solder alloys. In this research, mechanical measurements of isothermal aging effects and the resulting changes in the materials behavior of lead-free solders were performed. A novel specimen preparation procedure was developed where the solder uniaxial test specimens are formed in high precision rectangular cross-section glass tubes using a vacuum suction process. Using specimens fabricated with the developed procedure, isothermal aging effects and viscoplastic material behavior evolution have been characterized for 95.5Sn-4.0Ag-0.5Cu (SAC405) and 96.5Sn-3.0Ag-0.5Cu (SAC305) lead-free solders, which are commonly used as the solder ball alloy in lead-free BGAs and other components. Analogous tests were performed with 63Sn-37Pb eutectic solder samples for comparison purposes. Up to 40% reduction in tensile strength was observed for water quenched specimens after two months of aging at room temperature. Creep deformation also increased dramatically with increasing aging durations. Microstructural changes during room temperature aging were also observed and recorded for the solder alloys and correlated with the observed mechanical behavior changes. Aging effects at elevated temperatures for up to 6 months were also investigated. Thermal aging caused significant tensile strength loss and deterioration of creep deformation. The thermal aging results also showed that after an initial tensile strength drop, the Sn-Pb eutectic solder reached a relatively stable stage after 200 hours of aging. However, for SAC alloy, both the tensile and

  3. Fragrance composition of Dendrophylax lindenii (Orchidaceae using a novel technique applied in situ

    Directory of Open Access Journals (Sweden)

    James J. Sadler

    2012-02-01

    Full Text Available The ghost orchid, Dendrophylax lindenii (Lindley Bentham ex Rolfe (Orchidaceae, is one of North America’s rarest and well-known orchids. Native to Cuba and SW Florida where it frequents shaded swamps as an epiphyte, the species has experienced steady decline. Little information exists on D. lindenii’s biology in situ, raising conservation concerns. During the summer of 2009 at an undisclosed population in Collier County, FL, a substantial number (ca. 13 of plants initiated anthesis offering a unique opportunity to study this species in situ. We report a new technique aimed at capturing floral headspace of D. lindenii in situ, and identified volatile compounds using gas chromatography mass spectrometry (GC/MS. All components of the floral scent were identified as terpenoids with the exception of methyl salicylate. The most abundant compound was the sesquiterpene (E,E-α-farnesene (71% followed by (E-β-ocimene (9% and methyl salicylate (8%. Other compounds were: linalool (5%, sabinene (4%, (E-α-bergamotene (2%, α-pinene (1%, and 3-carene (1%. Interestingly, (E,E-α-farnesene has previously been associated with pestiferous insects (e.g., Hemiptera. The other compounds are common floral scent constituents in other angiosperms suggesting that our in situ technique was effective. Volatile capture was, therefore, possible without imposing physical harm (e.g., inflorescence detachment to this rare orchid.

  4. Evaluation on Dorsey Method in Surface Tension Measurement of Solder Liquids Containing Surfactants

    Science.gov (United States)

    Zhao, Xingke; Xie, Feiming; Fan, Jinsheng; Liu, Dayong; Huang, Jihua; Chen, Shuhai

    2018-06-01

    With the purpose of developing a feasible approach for measuring the surface tension of solders containing surfactants, the surface tension of Sn-3Ag-0.5Cu-xP solder alloys, with various drop sizes as well as different phosphorus (P) content, was evaluated using the Dorsey method based on the sessile drop test. The results show that the accuracy of the surface tension calculations depends on both of sessile drop size and the liquid metal composition. With a proper drop size, in the range of 4.5 mm to 5.3 mm in equivalent spherical diameters, the deviation of the surface tension calculation can be limited to 1.43 mN·m-1 and 6.30 mN·m-1 for SnAgCu and SnAgCu-P, respectively. The surface tension of SnAgCu-xP solder alloys decreases quickly to a minimum value when the P content reaches 0.5 wt% and subsequently increases slowly with the P content further increasing. The formation of a P-enriched surface layer and Sn4P3 intermetallic phases is regarded to be responsible for the decreasing and subsequent increasing of surface tension, respectively.

  5. Reinforcement of high-risk anastomoses using laser-activated protein solders: a clinical study

    Science.gov (United States)

    Libutti, Steven K.; Bessler, Marc; Chabot, J.; Bass, Lawrence S.; Oz, Mehmet C.; Auteri, Joseph S.; Kirsch, Andrew J.; Nowygrod, Roman; Treat, Michael R.

    1993-07-01

    Anastomotic leakage or breakdown can result in catastrophic complications and significantly increased post-operative morbidity and mortality. Certain anastomoses are subject to a higher incidence of disruption and are therefore termed high risk. In an attempt to decrease the risk of anastomotic leaks, we reinforced sutured anastomoses with a laser activated protein solder in patients undergoing esophagojejunostomies (n equals 2), lung transplantation (n equals 2), and pancreaticojejunostomies (Whipple procedure, n equals 5). The protein solder was composed of 1.0 ml of a 25% human albumin solution, 1.0 ml of sodium hyaluronate, and 0.1 ml of Cardiogreen dye. This composition was applied to the sutured anastomosis and activated with an 860 nm pulsed diode laser. Drains were placed when appropriate and patients were followed for up to 10 months post-operatively and assessed for clinical signs of anastomotic leaks. Results to data demonstrated that there were no immediate complications as a result of the procedure. Operative time was not significantly lengthened. There were no cases of clinically significant leakage from any of the reinforced anastomoses. Laser activated protein solders may help to reduce the incidence of leakage in high risk anastomoses. Large numbers of patients and longer follow-up is needed however, to draw significant conclusions.

  6. In situ one-pot preparation of reduced graphene oxide/polyaniline composite for high-performance electrochemical capacitors

    International Nuclear Information System (INIS)

    Chen, Nali; Ren, Yapeng; Kong, Peipei; Tan, Lin; Feng, Huixia; Luo, Yongchun

    2017-01-01

    Highlights: • A new method to prepare reduced graphene oxide/polyaniline composite is developed. • Aniline serves as a reduction for graphene oxide under weak alkali condition. • Different characterizations confirm that GO can be effectively reduced by aniline. • A high specific capacitance of 524.4 F·g"−"1 is obtained at 0.5 A·g"−"1. - Abstract: Reduced graphene oxide/polyaniline (rGO/PANI) composites are prepared through an effective in situ one-pot synthesis route that includes the reduction of graphene oxide (GO) by aniline under weak alkali condition via hydrothermal method and then followed by in situ polymerization of aniline. X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope are employed to reveal that GO is successfully reduced by aniline under weak alkali condition and PANI can be deposited on the surfaces of reduced graphene oxide (rGO) sheets. The effect of rGO is optimized by tuning the mass ratios of aniline to GO to improve the electrochemical performance of rGO/PANI composites. The maximum specific capacitance of rGO/PANI composites achieves 524.4 F/g with a mass ratio of aniline to GO 10:1 at a current density of 0.5 A/g, in comparison to the specific capacitance of 397 F/g at the same current density of pure PANI. Particularly, the specific capacity retention rate is 81.1% after 2000 cycles at 100 mv/s scan rate, which is an improvement over that of pure PANI (55.5%).

  7. Structure property relationship of biological nano composites studies by combination of in-situ synchrotron scattering and mechanical tests

    International Nuclear Information System (INIS)

    Martinschitz, K.

    2005-06-01

    Biological materials represent hierarchical nano fibre composites with complicated morphology and architecture varying on the nm level. The mechanical response of those materials is influenced by many parameters like chemical composition and crystal structure of constituents, preferred orientation, internal morphology with specific sizes of features etc. In-situ wide-angle x-ray scattering (WAXS) combined with mechanical tests provide a unique means to evaluate structural changes in biological materials at specific stages of tensile experiments. In this way it is possible to identify distinct architectural/compositional elements responsible for specific mechanical characteristics of the biological materials. In this thesis, structure-property relationship is analyzed using in-situ WAXS in the tissues of Picea abies, coir fibre, bacterial cellulose and cellulose II based composites. The experiments were performed at the beamline ID01 of European synchrotron radiation facility in Grenoble, France. The tissues were strained in a tensile stage, while the structural changes were monitored using WAXS. Complex straining procedures were applied including cyclic straining. One of the main goals was to understand the stiffness recovery and strain hardening effects in the tissues. The results demonstrate that, in all cellulosics, the orientation of the cellulose crystallites is only the function of the external strain while the stiffness depends on the specific stage of the tensile experiment. Whenever the strain is increased, the tissues exhibit stiffness equal or larger than the initial one. The recovery of the mechanical function is attributed to the molecular mechanistic effects operating between the crystalline domains of the cellulose. (author)

  8. In situ one-pot preparation of reduced graphene oxide/polyaniline composite for high-performance electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Nali [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, Gansu (China); State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, Gansu (China); Ren, Yapeng; Kong, Peipei; Tan, Lin [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, Gansu (China); Feng, Huixia, E-mail: fenghx@lut.cn [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, Gansu (China); Luo, Yongchun, E-mail: luoyc@lut.cn [State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou 730050, Gansu (China)

    2017-01-15

    Highlights: • A new method to prepare reduced graphene oxide/polyaniline composite is developed. • Aniline serves as a reduction for graphene oxide under weak alkali condition. • Different characterizations confirm that GO can be effectively reduced by aniline. • A high specific capacitance of 524.4 F·g{sup −1} is obtained at 0.5 A·g{sup −1}. - Abstract: Reduced graphene oxide/polyaniline (rGO/PANI) composites are prepared through an effective in situ one-pot synthesis route that includes the reduction of graphene oxide (GO) by aniline under weak alkali condition via hydrothermal method and then followed by in situ polymerization of aniline. X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope and transmission electron microscope are employed to reveal that GO is successfully reduced by aniline under weak alkali condition and PANI can be deposited on the surfaces of reduced graphene oxide (rGO) sheets. The effect of rGO is optimized by tuning the mass ratios of aniline to GO to improve the electrochemical performance of rGO/PANI composites. The maximum specific capacitance of rGO/PANI composites achieves 524.4 F/g with a mass ratio of aniline to GO 10:1 at a current density of 0.5 A/g, in comparison to the specific capacitance of 397 F/g at the same current density of pure PANI. Particularly, the specific capacity retention rate is 81.1% after 2000 cycles at 100 mv/s scan rate, which is an improvement over that of pure PANI (55.5%).

  9. Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part II. Intermetallic Coarsening Behavior of Rapidly Solidified Solders After Multiple Reflows

    Science.gov (United States)

    Reeve, Kathlene N.; Choquette, Stephanie M.; Anderson, Iver E.; Handwerker, Carol A.

    2016-12-01

    Controlling the size, dispersion, and stability of intermetallic compounds in lead-free solder alloys is vital to creating reliable solder joints regardless of how many times the solder joints are melted and resolidified (reflowed) during circuit board assembly. In this article, the coarsening behavior of Cu x Al y and Cu6Sn5 in two Sn-Cu-Al alloys, a Sn-2.59Cu-0.43Al at. pct alloy produced via drip atomization and a Sn-5.39Cu-1.69Al at. pct alloy produced via melt spinning at a 5-m/s wheel speed, was characterized after multiple (1-5) reflow cycles via differential scanning calorimetry between the temperatures of 293 K and 523 K (20 °C and 250 °C). Little-to-no coarsening of the Cu x Al y particles was observed for either composition; however, clustering of Cu x Al y particles was observed. For Cu6Sn5 particle growth, a bimodal size distribution was observed for the drip atomized alloy, with large, faceted growth of Cu6Sn5 observed, while in the melt spun alloy, Cu6Sn5 particles displayed no significant increase in the average particle size, with irregularly shaped, nonfaceted Cu6Sn5 particles observed after reflow, which is consistent with shapes observed in the as-solidified alloys. The link between original alloy composition, reflow undercooling, and subsequent intermetallic coarsening behavior was discussed by using calculated solidification paths. The reflowed microstructures suggested that the heteroepitaxial relationship previously observed between the Cu x Al y and the Cu6Sn5 was maintained for both alloys.

  10. Fatigue and thermal fatigue of Pb-Sn solder joints

    International Nuclear Information System (INIS)

    Frear, D.; Grivas, D.; McCormack, M.; Tribula, D.; Morris, J.W. Jr.

    1987-01-01

    This paper presents a fundamental investigation of the fatigue and thermal fatigue characteristics, with an emphasis on the microstructural development during fatigue, of Sn-Pb solder joints. Fatigue tests were performed in simple shear on both 60Sn-40Pb and 5Sn-95Pb solder joints. Isothermal fatigue tests show increasing fatigue life of 60Sn-40Pb solder joints with decreasing strain and temperature. In contrast, such behavior was not observed in the isothermal fatigue of 5Sn-95Pb solder joints. Thermal fatigue results on 60Sn-40Pb solder cycled between -55 0 C and 125 0 C show that a coarsened region develops in the center of the joint. Both Pb-rich and Sn-rich phases coarsen, and cracks form within these coarsened regions. The failure mode 60Sn-40Pb solder joints in thermal and isothermal fatigue is similar: cracks form intergranularly through the Sn-rich phase or along Sn/Pb interphase boundaries. Extensive cracking is found throughout the 5Sn-95Pb joint for both thermal and isothermal fatigue. In thermal fatigue the 5Sn-95Pb solder joints failed after fewer cycles than 60Sn-40Pb

  11. Al-Si/Al2O3 in situ composite prepared by displacement reaction of CuO/Al system

    Directory of Open Access Journals (Sweden)

    Zhang Jing

    2010-02-01

    Full Text Available Al2O3 particle-reinforced ZL109 composite was prepared by in situ reaction between CuO and Al. The microstructure was observed by means of OM, SEM and TEM. The Al2O3 particles in sub-micron sizes distribute uniformly in the matrix, and the Cu displaced from the in situ reaction forms net-like alloy phases with other alloy elements. The hardness and the tensile strength of the composites at room temperature have a slight increase as compared to that of the matrix. However, the tensile strength at 350 ℃ has reached 90.23 MPa, or 16.92 MPa higher than that of the matrix. The mechanism of the reaction in the CuO/Al system was studied by using of differential scanning calorimetry(DSC and thermodynamic calculation. The reaction between CuO and Al involves two steps. First, CuO reacts with Al to form Cu2O and Al2O3 at the melting temperature of the matrix alloy, and second, Cu2O reacts with Al to form Cu and Al2O3 at a higher temperature. At ZL109 casting temperature of 750–780 ℃, the second step can also take place because of the effect of exothermic reaction of the first step.

  12. Multi-sensor system for in situ shape monitoring and damage identification of high-speed composite rotors

    Science.gov (United States)

    Philipp, K.; Filippatos, A.; Kuschmierz, R.; Langkamp, A.; Gude, M.; Fischer, A.; Czarske, J.

    2016-08-01

    Glass fibre-reinforced polymer (GFRP) composites offer a higher stiffness-to-weight ratio than conventional rotor materials used in turbomachinery. However, the material behaviour of GFRP high-speed rotors is difficult to predict due to the complexity of the composite material and the dynamic loading conditions. Consequently dynamic expansion measurements of GRFP rotors are required in situ and with micron precision. However, the whirling motion amplitude is about two orders of magnitude higher than the desired precision. To overcome this problem, a multi-sensor system capable of separating rotor expansion and whirling motion is proposed. High measurement rates well above the rotational frequency and micron uncertainty are achieved at whirling amplitudes up to 120μm and surface velocities up to 300 m/s. The dynamic elliptical expansion of a GFRP rotor is investigated in a rotor loading test rig under vacuum conditions. In situ measurements identified not only the introduced damage but also damage initiation and propagation.

  13. In-Situ Preparation of Aramid-Multiwalled CNT Nano-Composites: Morphology, Thermal Mechanical and Electric Properties

    Directory of Open Access Journals (Sweden)

    Jessy Shiju

    2018-05-01

    Full Text Available In this work in-situ polymerization technique has been used to chemically link the functionalized multiwalled carbon nanotubes (CNTs with aramid matrix chains. Phenylene diamine monomers were reacted in the first stage with the carboxylic acid functionalized CNTs and then amidized in-situ using terephthaloyl chloride generating chemically bonded CNTs with the matrix. Various proportions of the CNTs were used to prepare the hybrid materials. The functionalization procedure was studied by Fourier transform infrared (FTIR spectroscopy and composite morphology investigated by scanning electron microscopy (SEM. Thermal mechanical properties of these hybrids, together with those where pristine CNTs with similar loadings were used, are compared using tensile and dynamic mechanical analysis (DMA. The tensile strength and temperature involving α-relaxations on CNT loading increased with CNT loading in both systems, but much higher values, i.e., 267 MPa and 353 °C, respectively, were obtained in the chemically bonded system, which are related to the nature of the interface developed as observed in SE micrographs. The water absorption capacity of the films was significantly reduced from 6.2 to 1.45% in the presence pristine CNTs. The inclusion of pristine CNTs increased the electric conductivity of the aramid films with a minimum threshold value at the loading of 3.5 wt % of CNTs. Such mechanically strong and thermally stable aramid and easily processable composites can be suitable for various applications including high performance films, electromagnetic shielding and radar absorption.

  14. Development of Guidelines for In-Situ Repair of SLS-Class Composite Flight Hardware

    Science.gov (United States)

    Weber, Thomas P., Jr.; Cox, Sarah B.

    2018-01-01

    The purpose of composite repair development at KSC (John F. Kennedy Space Center) is to provide support to the CTE (Composite Technology for Exploration) project. This is a multi-space center effort with the goal of developing bonded joint technology for SLS (Space Launch System) -scale composite hardware. At KSC, effective and efficient repair processes need to be developed to allow for any potential damage to composite components during transport or launch preparation. The focus of the composite repair development internship during the spring of 2018 was on the documentation of repair processes and requirements for process controls based on techniques developed through hands-on work with composite test panels. Three composite test panels were fabricated for the purpose of repair and surface preparation testing. The first panel included a bonded doubler and was fabricated to be damaged and repaired. The second and third panels were both fabricated to be cut into lap-shear samples to test the strength of bond of different surface preparation techniques. Additionally, jointed composite test panels were impacted at MSFC (Marshall Space Flight Center) and analyzed for damage patterns. The observations after the impact tests guided the repair procedure at KSC to focus on three repair methods. With a finalized repair plan in place, future work will include the strength testing of different surface preparation techniques, demonstration of repair methods, and repair of jointed composite test panels being impacted at MSFC.

  15. In-Situ EBCs for High Performance Composite Propulsion Components, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Silicon Carbide based ceramic matrix composites (CMCs) offer the potential to fundamentally change the design and manufacture of aeronautical and space propulsion...

  16. In-situ EBCs for High Performance Composite Propulsion Components, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Silicon Carbide based ceramic matrix composites (CMCs) offer the potential to fundamentally change the design and manufacture of aeronautical and space propulsion...

  17. In-situ fatigue life prognosis for composite laminates based on stiffness degradation

    Data.gov (United States)

    National Aeronautics and Space Administration — In this paper, a real-time composite fatigue life prognosis framework is proposed. The proposed methodology combines Bayesian inference, piezoelectric sensor...

  18. Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

    International Nuclear Information System (INIS)

    Sujan, G.K.; Haseeb, A.S.M.A.; Afifi, A.B.M.

    2014-01-01

    Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu 6 Sn 5 from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping of flux

  19. Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sujan, G.K., E-mail: sgkumer@gmail.com; Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Afifi, A.B.M., E-mail: amalina@um.edu.my

    2014-11-15

    Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu{sub 6}Sn{sub 5} from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping

  20. Influence of in situ formed ZrB2 particles on microstructure and mechanical properties of AA6061 metal matrix composites

    International Nuclear Information System (INIS)

    Dinaharan, I.; Murugan, N.; Parameswaran, Siva

    2011-01-01

    Highlights: → In situ fabrication of aluminium metal matrix composite reinforced ZrB 2 particles. → Colour metallography of composites. → Improvement of matrix properties by ZrB 2 particles. → Sliding wear behaviour of in situ composites. - Abstract: Particulate reinforced metal matrix composites (PMMCs) have gained considerable amount of research emphasis and attention in the present era. Research is being carried out across the globe to produce new combination of PMMCs. PMMCs are prepared by adding a variety of ceramic particles with monolithic alloys using several techniques. An attempt has been made to produce aluminium metal matrix composites reinforced with zirconium boride (ZrB 2 ) particles by the in situ reaction of K 2 ZrF 6 and KBF 4 salts with molten aluminium. The influence of in situ formed ZrB 2 particles on the microstructure and mechanical properties of AA6061 alloy was studied in this work. The in situ formed ZrB 2 particles significantly refined the microstructure and enhanced the mechanical properties of AA6061 alloy. The weight percentage of ZrB 2 was varied from 0 to 10 in steps of 2.5. Improvement of hardness, ultimate tensile strength and wear resistance of AA6061 alloy was observed with the increase in ZrB 2 content.

  1. Assessment of potential solder candidates for high temperature applications

    DEFF Research Database (Denmark)

    pressure to eliminate lead containing materials despite the fact that materials for high Pb containing alloys are currently not affected by any legislations. A tentative assessment was carried out to determine the potential solder candidates for high temperature applications based on the solidification...... criterion, phases predicted in the bulk solder and the thermodynamic stability of chlorides. These promising solder candidates were precisely produced using the hot stage microscope and its respective anodic and cathodic polarization curves were investigated using a micro-electrochemical set up...

  2. Manipulation and soldering of carbon nanotubes using atomic force microscope

    International Nuclear Information System (INIS)

    Kashiwase, Yuta; Ikeda, Takayuki; Oya, Takahide; Ogino, Toshio

    2008-01-01

    Manipulation of carbon nanotubes (CNTs) by an atomic force microscope (AFM) and soldering of CNTs using Fe oxide nanoparticles are described. We succeeded to separate a CNT bundle into two CNTs or CNT bundles, to move the separated CNT to a desirable position, and to bind it to another bundle. For the accurate manipulation, load of the AFM cantilever and frequency of the scan were carefully selected. We soldered two CNTs using an Fe oxide nanoparticle prepared from a ferritin molecule. The adhesion forces between the soldered CNTs were examined by an AFM and it was found that the CNTs were bound, though the binding force was not strong

  3. Development of in-situ ZrC reinforced iron based composites for wear resistance applications

    International Nuclear Information System (INIS)

    Bandyopadhyay, T.K.; Das, K.

    2002-01-01

    A common objective behind the processing of iron-based composites is to improve the wear resistance of steels by incorporating some reinforcing phases, e.g., carbides and oxides. In the present investigation, iron-based zirconium carbide reinforced composite is produced by the aluminothermic reduction of zircon sand (ZrSiO 4 ) and blue dust (Fe 2 O 3 ) in the presence of carbon. Aluminothermic reduction of blue dust and zircon sand, being highly exothermic in nature, essentially leads to a self-propagating high-temperature synthesis (SHS) of the Fe-ZrC composite. The as-cast composite is characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mechanical properties of the composite and the effect of heat treatment on the microstructure are evaluated. The composite possess sufficient hardness and promising abrasive wear resistance property. The abrasive wear resistance property of the Fe-ZrC composite is compared with that of a M2 grade tool material and it is found to be better than the tool material. The composite also possess good high temperature stability. (author)

  4. Potassium diperiodatocuprate-mediated preparation of poly(methyl methacrylate/organo-montmorillonite composites via in situ grafting copolymerization

    Directory of Open Access Journals (Sweden)

    2008-09-01

    Full Text Available In this study, potassium diperiodatocuprate (Cu3+ was selected as an initiator to prepare poly(methyl methacrylate/organo-montmorillonite composites (OMMT-g-PMMA by in situ graft copolymerization. Three synthetic parameters were systematically evaluated as a function of the temperature, the concentration of initiator, pH and the ratio of MMA to OMMT. It was found that Cu3+ was a highly efficient initiator for the preparation of OMMT-g-PMMA i.e., monomer conversion and grafting efficiency were as higher as 95%. The X-ray diffraction measurement showed the intercalation of PMMA chains into OMMT layers on base of an increasing basal spacing after polymerization. FTIR analysis also suggested that the PMMA chains were effectively grafted onto OMMT substrate. The enhanced thermal stabilities of OMMT-g-PMMA composites were confirmed by the thermal gravimetric analysis (TGA. Finally, a single-electron-transfer mechanism was proposed to illustrate the formation of radicals and the preparation process of OMMT-g-PMMA composites. Cu3+ can be used as an effective and practical initiator in preparing the organic/inorganic composite due to its high grafting efficiency and the milder reaction condition.

  5. Preparation and Wear Resistance of Aluminum Composites Reinforced with In Situ Formed TiO/Al2O3

    Science.gov (United States)

    Qin, Q. D.; Huang, B. W.; Li, W.; Zeng, Z. Y.

    2016-05-01

    An in situ TiO/Al2O3-reinforced Al composite is successfully prepared using a powder metallurgy route by the reaction of Ti2CO and Al powder. The Ti2CO powder is produced by carrying out a carbothermic reduction of titanium dioxide at 1000 °C. XRD results show that the final product is composed of Al, TiO, Al2O3, and Al3Ti. Morphology examination of the composite reveals the presence of bigger blocks of TiO and fine particles of Al2O3 and the volume fraction of reinforcement is found to range between 18 and 55%. As the volume fraction of the reinforced materials approaches 50%, the particles start to agglomerate. Dry sliding wear tests conducted using a conventional pin-on-disk testing machine show that the wear resistance of the composite is higher than that of the pure aluminum ingot. The wear rate of the composite increases almost linearly with the increase in the wear distance. The sliding wear test shows that as the volume fraction of the reinforced phase increases, the coefficient of friction decreases. The wear mechanism is also discussed.

  6. Synthesis of HNTs@PEDOT composites via in situ chemical oxidative polymerization and their application in electrode materials

    Science.gov (United States)

    Wang, Fang; Zhang, Xianhong; Ma, Yuhong; Yang, Wantai

    2018-01-01

    The hybrid composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and halloysite nanotubes (HNTs) was synthesized by a two-step process. First, poly(sodium styrene sulfonate) (PSSNa) was grafted onto HNTs via surface initiated atom transfer radical polymerization. Then with the HNTs-g-PSS as a template and the grafted PSS chains as the counterion dopant, PEDOT was precipitated onto the template via in situ oxidization polymerization of EDOT to form HNTs@PEDOT hybrid composites. The conductivity of HNTs@PEDOT can reach up to 9.35 S/cm with the content of 40% HNTs-g-PSS, which increased almost 78 times than that of pure PEDOT (about 0.12 S/cm) prepared at the similar condition. Further treated with p-toluenesulfonic acid (TsOH) as external dopant, the conductivity of HNTs@PEDOT increased to 24.3 S/cm. The electrochemical properties of the composites were investigated with cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy with three-electrode cell configuration. The results showed that the capacitance of HNTs@PEDOT composite increased 55% than that of pure PEDOT.

  7. Influence of Sintering Temperature on the Microstructure and Mechanical Properties of In Situ Reinforced Titanium Composites by Inductive Hot Pressing

    Directory of Open Access Journals (Sweden)

    Cristina Arévalo

    2016-11-01

    Full Text Available This research is focused on the influence of processing temperature on titanium matrix composites reinforced through Ti, Al, and B4C reactions. In order to investigate the effect of Ti-Al based intermetallic compounds on the properties of the composites, aluminum powder was incorporated into the starting materials. In this way, in situ TixAly were expected to form as well as TiB and TiC. The specimens were fabricated by the powder metallurgy technique known as inductive hot pressing (iHP, using a temperature range between 900 °C and 1400 °C, at 40 MPa for 5 min. Raising the inductive hot pressing temperature may affect the microstructure and properties of the composites. Consequently, the variations of the reinforcing phases were investigated. X-ray diffraction, microstructural analysis, and mechanical properties (Young’s modulus and hardness of the specimens were carried out to evaluate and determine the significant influence of the processing temperature on the behavior of the composites.

  8. Microstructure and mechanical properties of in situ TiC and Nd2O3 particles reinforced Ti-4.5 wt.%Si alloy composites

    International Nuclear Information System (INIS)

    Zhang, Xinjiang; Li, Yibin; Song, Guangping; Sun, Yue; Peng, Qingyu; Li, Yuxin; He, Xiaodong

    2011-01-01

    Highlights: → (TiC + Nd 2 O 3 )/Ti-4.5 wt.%Si composites were in situ synthesized. → The phase components and microstructures of the composites were investigated. → In situ reinforcements improve the mechanical properties of the matrix alloy. -- Abstract: (TiC + Nd 2 O 3 )/Ti-4.5 wt.%Si composites were in situ synthesized by a non-consumable arc-melting technology. The phases in the composites were identified by X-ray diffraction. Microstructures of the composites were observed by optical microscope and scanning electron microscope. The composite contains four phases: TiC, Nd 2 O 3 , Ti 5 Si 3 and Ti. The TiC and Nd 2 O 3 particles with dendritic and near-equiaxed shapes are well distributed in Ti-4.5 wt.%Si alloy matrix, and the fine Nd 2 O 3 particles exist in the network Ti + Ti 5 Si 3 eutectic cells and Ti matrix of the composites. The hardness and compressive strength of the composites are markedly higher than that of Ti-4.5 wt.%Si alloy. When the TiC content is fixed as 10 wt.% in the composites, the hardness is enhanced as the Nd 2 O 3 content increases from 8 wt.% to 13 wt.%, but the compressive strength peaks at the Nd 2 O 3 content of 8 wt.%.

  9. Effect of soldering techniques and gap distance on tensile strength of soldered Ni-Cr alloy joint.

    Science.gov (United States)

    Lee, Sang-Yeob; Lee, Jong-Hyuk

    2010-12-01

    The present study was intended to evaluate the effect of soldering techniques with infrared ray and gas torch under different gap distances (0.3 mm and 0.5 mm) on the tensile strength and surface porosity formation in Ni-Cr base metal alloy. Thirty five dumbbell shaped Ni-Cr alloy specimens were prepared and assigned to 5 groups according to the soldering method and the gap distance. For the soldering methods, gas torch (G group) and infrared ray (IR group) were compared and each group was subdivided by corresponding gap distance (0.3 mm: G3 and IR3, 0.5 mm: G5, IR5). Specimens of the experimental groups were sectioned in the middle with a diamond disk and embedded in solder blocks according to the predetermined distance. As a control group, 7 specimens were prepared without sectioning or soldering. After the soldering procedure, a tensile strength test was performed using universal testing machine at a crosshead speed 1 mm/min. The proportions of porosity on the fractured surface were calculated on the images acquired through the scanning electronic microscope. Every specimen of G3, G5, IR3 and IR5 was fractured on the solder joint area. However, there was no significant difference between the test groups (P > .05). There was a negative correlation between porosity formation and tensile strength in all the specimens in the test groups (P tensile strength of joints and porosity formations between the gas-oxygen torch soldering and infrared ray soldering technique or between the gap distance of 0.3 mm and 0.5 mm.

  10. Experimental Investigation on Mechanical and Turning Behavior of Al 7075/x% wt. TiB2-1% Gr In Situ Hybrid Composite

    Directory of Open Access Journals (Sweden)

    K. R. Ramkumar

    2015-01-01

    Full Text Available The present research work involves the study of AA 7075-TiB2-Gr in situ composite through stir casting route. This in situ method involves formation of reinforcements within the matrix by the chemical reaction of two or more compounds which also produces some changes in the matrix material within the vicinity. Titanium Diboride (TiB2 and graphite were the reinforcement in a matrix of AA 7075 alloy. The composite was prepared with the formation of the reinforcement inside the molten matrix by adding salts of Potassium Tetrafluoroborate (KBF4 and Potassium Hexafluorotitanate (K2TiF6. The samples were taken under casted condition and the properties of the composite were tested by conducting characterization using X-ray diffraction (XRD, hardness test, flexural strength by using three-point bend test, scanning electron microscope (SEM, optical microstructure, grain size analysis, and surface roughness. It was found that good/excellent mechanical properties were obtained in AA 7075-TiB2-Gr reinforced in situ hybrid composite compared to alloy due to particulate strengthening of ceramic particles of TiB2 in the matrix. Further, Al 7075-3% TiB2-1% Gr hybrid in situ composite exhibited improved machinability over the alloy and composites due to self-lubricating property given by the Gr particles in the materials.

  11. In Situ Processing Route for Uniform Density Carbon-Carbon Composites

    National Research Council Canada - National Science Library

    Hoffman, Wesley

    2001-01-01

    .... These composites possess a unique set of properties that make them ideal materials for high temperature structural uses, such as in rocket propulsion components, hypersonic vehicles, and aircraft brakes...

  12. In-situ microfibrillar PP–PA6 composites: rheological, morphological ...

    Indian Academy of Sciences (India)

    MS received 15 June 2016; accepted 21 November 2016; published online 23 August 2017. Abstract. ... Petrochemical Company in South Korea, branded as CM-. 1120H, as ..... amount, fibres act as a filler and reduce the composite strength.

  13. In-situ Non-Invasive Imaging of Liquid-Immersed Thin Film Composite Membranes

    KAUST Repository

    Ogieglo, Wojciech; Pinnau, Ingo; Wessling, Matthias

    2017-01-01

    We present a non-invasive method to directly image liquid-immersed thin film composite membranes. The approach allows accessing information not only on the lateral distribution of the coating thickness, including variations in its swelling

  14. Role of Phase Composition of PEO Coatings on AA2024 for In-Situ LDH Growth

    Directory of Open Access Journals (Sweden)

    Maria Serdechnova

    2017-11-01

    Full Text Available Plasma electrolytic oxidation (PEO is an environmentally friendly anodizing technique leading to the formation of a ceramic-like coatings under high-voltage discharges. Layered double hydroxides (LDHs were grown directly on γ, α, and amorphous Al2O3 powders, respectively, in order to investigate the phase responsible for in-situ LDH growth on PEO coating. Furthermore, it is shown that LDH growth is limited by the high tortuosity of the PEO layer and the accessibility of Al ( OH 4 − anions from the substrate covered with thin amorphous aluminum oxide, through the pores.

  15. Microstructure Evolution and Mechanical Properties of Al-TiB2/TiC In Situ Aluminum-Based Composites during Accumulative Roll Bonding (ARB Process

    Directory of Open Access Journals (Sweden)

    Jinfeng Nie

    2017-01-01

    Full Text Available In this study, a kind of Al-TiB2/TiC in situ composite was successfully prepared using the melt reaction method and the accumulative roll-bonding (ARB technique. The microstructure evolution of the composites with different deformation treatments was characterized using field emission scanning electron microscopy (FESEM and a transmission electron microscope (TEM. The mechanical properties of the Al-TiB2/TiC in situ composite were also studied with tensile and microhardness tests. It was found that the distribution of reinforcement particles becomes more homogenous with an increasing ARB cycle. Meanwhile, the mechanical properties showed great improvement during the ARB process. The ultimate tensile strength (UTS and microhardness of the composites were increased to 173.1 MPa and 63.3 Hv after two ARB cycles, respectively. Furthermore, the strengthening mechanism of the composite was analyzed based on its fracture morphologies.

  16. Interfacial Reaction of Sn-Ag-Cu Lead-Free Solder Alloy on Cu: A Review

    Directory of Open Access Journals (Sweden)

    Liu Mei Lee

    2013-01-01

    Full Text Available This paper reviews the function and importance of Sn-Ag-Cu solder alloys in electronics industry and the interfacial reaction of Sn-Ag-Cu/Cu solder joint at various solder forms and solder reflow conditions. The Sn-Ag-Cu solder alloys are examined in bulk and in thin film. It then examines the effect of soldering conditions to the formation of intermetallic compounds such as Cu substrate selection, structural phases, morphology evolution, the growth kinetics, temperature and time is also discussed. Sn-Ag-Cu lead-free solder alloys are the most promising candidate for the replacement of Sn-Pb solders in modern microelectronic technology. Sn-Ag-Cu solders could possibly be considered and adapted in miniaturization technologies. Therefore, this paper should be of great interest to a large selection of electronics interconnect materials, reliability, processes, and assembly community.

  17. Development of a soft-soldering system for aluminum

    Science.gov (United States)

    Falke, W. L.; Lee, A. Y.; Neumeier, L. A.

    1983-03-01

    The method employs application of a thin nickel copper alloy coating to the substrate, which enables the tin lead solders to wet readily and spread over the areas to be joined. The aluminum substrate is mechanically or chemically cleaned to facilitate bonding to a minute layer of zinc that is subsequently applied, with an electroless zincate solution. The nickel copper alloy (30 to 70 pct Ni) coating is then applied electrolytically over the zinc, using immersion cell or brush coating techniques. Development of acetate electrolytes has permitted deposition of the proper alloys coatings. The coated areas can then be readily joined with conventional tin lead solders and fluxs. The joints so formed are ductile, strong, and relatively corrosion resistant, and exhibit strengths equivalent to those formed on copper and brass when the same solders and fluxes are used. The method has also been employed to soft solder magnesium alloys.

  18. Development of gold based solder candidates for flip chip assembly

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2009-01-01

    Flip chip technology is now rapidly replacing the traditional wire bonding interconnection technology in the first level packaging applications due to the miniaturization drive in the microelectronics industry. Flip chip assembly currently involves the use of high lead containing solders...

  19. The effect of powder composition on the morphology of in situ TiC composite coating deposited by Laser-Assisted Powder Deposition (LAPD)

    International Nuclear Information System (INIS)

    Emamian, Ali; Corbin, Stephen F.; Khajepour, Amir

    2012-01-01

    Highlights: ► The novel idea was to develop Fe-TiC containing high volume fraction of TiC. ► Increased TiC volume fraction enhanced clad hardness profile. ► Both, laser conditions and fed powder compositions affected the clad microstructure. ► Hardness and TiC volume fraction was maximized by control over melt pool composition. ► Hardness/TiC volume fraction was maximized by controlling of laser parameters. - Abstract: In this paper, the effect of powder composition on in situ TiC formation within an Fe-based matrix coating during laser cladding was studied. Different atomic ratios of C:Ti (45% and 55%) were selected in order to adjust the matrix from an Fe-Ti-based composition to an Fe-C-based one. Fe percentages of 70, 60, 50 and 10 wt% were explored to increase the volume fraction of TiC in the clad. Results showed that chemical composition affects the TiC morphology as well as the TiC distribution and hardness profile in the clad. By increasing the C:Ti ratio from 45 at% to 55 at%, the volume fraction of the formed TiC increases. A higher volume fraction of TiC in the clad resulted in increases clad hardness. SEM and EDS analyses were used to characterize the phases in the clad, while increasing the C ratio promoted the formation of excess graphite in the Fe matrix.

  20. The effect of powder composition on the morphology of in situ TiC composite coating deposited by Laser-Assisted Powder Deposition (LAPD)

    Energy Technology Data Exchange (ETDEWEB)

    Emamian, Ali, E-mail: aemamian@uwaterloo.ca [Research Associate and Postdoctoral fellow in the Department of Mechanics and Mechatronics, University of Waterloo, 200 University West, Waterloo, N2L 4 3G1 (Canada); Corbin, Stephen F. [Professor and Canada Research Chair in the Department of Civil and Resource Engineering, Dalhousie University, Halifax, Nova Scotia, P.O. Box 15000, B3H 5 4R2 (Canada); Khajepour, Amir [Professor and Canada Research Chair in the Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo (Canada)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The novel idea was to develop Fe-TiC containing high volume fraction of TiC. Black-Right-Pointing-Pointer Increased TiC volume fraction enhanced clad hardness profile. Black-Right-Pointing-Pointer Both, laser conditions and fed powder compositions affected the clad microstructure. Black-Right-Pointing-Pointer Hardness and TiC volume fraction was maximized by control over melt pool composition. Black-Right-Pointing-Pointer Hardness/TiC volume fraction was maximized by controlling of laser parameters. - Abstract: In this paper, the effect of powder composition on in situ TiC formation within an Fe-based matrix coating during laser cladding was studied. Different atomic ratios of C:Ti (45% and 55%) were selected in order to adjust the matrix from an Fe-Ti-based composition to an Fe-C-based one. Fe percentages of 70, 60, 50 and 10 wt% were explored to increase the volume fraction of TiC in the clad. Results showed that chemical composition affects the TiC morphology as well as the TiC distribution and hardness profile in the clad. By increasing the C:Ti ratio from 45 at% to 55 at%, the volume fraction of the formed TiC increases. A higher volume fraction of TiC in the clad resulted in increases clad hardness. SEM and EDS analyses were used to characterize the phases in the clad, while increasing the C ratio promoted the formation of excess graphite in the Fe matrix.

  1. Characterization of boron carbide particulate reinforced in situ copper surface composites synthesized using friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Sathiskumar, R., E-mail: sathiscit2011@gmail.com [Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore, 641 014 Tamil Nadu (India); Murugan, N., E-mail: murugan@cit.edu.in [Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore, 641 014 Tamil Nadu (India); Dinaharan, I., E-mail: dinaweld2009@gmail.com [Department of Mechanical Engineering, V V College of Engineering, Tisaiyanvilai, 627 657 Tamil Nadu (India); Vijay, S.J., E-mail: vijayjoseph@karunya.edu [Centre for Research in Metallurgy (CRM), School of Mechanical Sciences, Karunya University, Coimbatore, 641 114 Tamil Nadu (India)

    2013-10-15

    Friction stir processing has evolved as a novel solid state technique to fabricate surface composites. The objective of this work is to apply the friction stir processing technique to fabricate boron carbide particulate reinforced copper surface composites and investigate the effect of B{sub 4}C particles and its volume fraction on microstructure and sliding wear behavior of the same. A groove was prepared on 6 mm thick copper plates and packed with B{sub 4}C particles. The dimensions of the groove was varied to result in five different volume fractions of B{sub 4}C particles (0, 6, 12, 18 and 24 vol.%). A single pass friction stir processing was done using a tool rotational speed of 1000 rpm, travel speed of 40 mm/min and an axial force of 10 kN. Metallurgical characterization of the Cu/B{sub 4}C surface composites was carried out using optical microscope and scanning electron microscope. The sliding wear behavior was evaluated using a pin-on-disk apparatus. Results indicated that the B{sub 4}C particles significantly influenced the area, dispersion, grain size, microhardness and sliding wear behavior of the Cu/B{sub 4}C surface composites. When the volume fraction of B{sub 4}C was increased, the wear mode changed from microcutting to abrasive wear and wear debris was found to be finer. Highlights: • Fabrication of Cu/B{sub 4}C surface composite by friction stir processing • Analyzing the effect of B{sub 4}C particles on the properties of Cu/B4C surface composite • Increased volume fraction of B{sub 4}C particles reduced the area of surface composite. • Increased volume fraction of B{sub 4}C particles enhanced the microhardness and wear rate. • B{sub 4}C particles altered the wear mode from microcutting to abrasive.

  2. Strength of joints brazed with two-phase solders

    International Nuclear Information System (INIS)

    Shnyakin, N.S.; Parfenova, L.V.; Ekatova, A.S.; Prilepskaya, I.V.

    1976-01-01

    Dependence of the structure and strength of soldered joints upon a gap size in case of 1Kh18N10T stainless steel soldering with a double-phase solder of Ni-Zn-Cu system is described. Butt and lap joints have been subjected to soldering with gas-flame and induction heating. The optimum conditions of the solder crystallization are determined with wedge-gap samples. The studies show that the character of distribution of a fusible β-phase in metal depends upon a gap size. With gaps up to 0.1 mm the β-phase enriched with a fusible component (zinc) runs as a continuous thin interlayer in the middle of the seam. As a result of zinc evaporation from the β-phase this interlayer becomes internally oxidized. After the sample is broken an oxidized fracture gives one the impression of a poor fusion in the middle part of the joint. The ultimate strength of butt joints is 15-20 kgf/sq.mm. A value of thermal expansion of 1Kh18N10T steel samples, 1-5 mm thick, has been experimentally determined for butt soldering. The elongation of two halves of the sample is measured by an indicator and proved to be 0.89 mm for a 50x50x2 mm sample at a soldering temperature of 1.100 deg C. The paper presents methods for the calculation of an optimal gap value for butt soldering with a local gas-flame and induction heating

  3. Polypropylene Nano composites Obtained by In Situ Polymerization Using Metallocenes Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

    International Nuclear Information System (INIS)

    Zapata, P.; Quijada, R.

    2012-01-01

    Polypropylene nano composites containing silica nanospheres based on the sol-gel methods were produced via in situ polymerization using a rac-Et(Ind) 2 ZrCl 2 /methylaluminoxane (MAO) system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind) 2 ZrCl 2 )/(MAO) directly into the reactor, and in route 2 the metallocenes rac-Et(Ind) 2 ZrCl 2 was supported on silica nanospheres pretreated with (MAO). SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP) nano composites obtained by both routes had a slightly higher percent crystallinity and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM) images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nano composites obtained by the support system (route 2).

  4. Development of in-Situ Al-Si/CuAl₂ Metal Matrix Composites: Microstructure, Hardness, and Wear Behavior.

    Science.gov (United States)

    Tash, Mahmoud M; Mahmoud, Essam R I

    2016-06-02

    In the present work, in-situ metal matrix composites were fabricated through squeeze casting. The copper particles were dispersed with different weight percentages (3%, 6%, 10%, and 15%) into Al-12% Si piston alloy. Also, heat treatments were performed at 380 °C and 450 °C for holding times of 6 and 18 h. The microstructures, X-ray diffractometer (XRD) pattern, hardness, and wear characteristics were evaluated. The results showed that these copper particles have reacted with the aluminum under all of the aforementioned processing conditions resulting in the formation of fine copper aluminide intermetallics. Most of the intermetallics were CuAl₂, while AlCu appeared in a small ratio. Additionally, these intermetallics were homogenously distributed within the alloy matrix with up to 6% Cu addition. The amounts of those intermetallics increased after performing heat treatment. Most of these intermetallics were CuAl₂ at 380 °C, while the Cu-rich intermetallics appeared at 450 °C. Increasing the holding time to 18 h, however, led to grain coarsening and resulted in the formation of some cracks. The hardness of the resulting composite materials was improved. The hardness value reached to about 170 HV after heat treating at 380 °C for 8 h. The wear resistance of the resulting composite materials was remarkably improved, especially at lower additions of Cu and at the lower heat treatment temperature.

  5. In-situ heating TEM observation of microscopic structural changes of size-controlled metallic copper/gelatin composite.

    Science.gov (United States)

    Narushima, Takashi; Hyono, Atsushi; Nishida, Naoki; Yonezawa, Tetsu

    2012-10-01

    Copper/gelatin composite particles with controlled sizes were prepared at room temperature from cupric sulfate pentahydrate in the presence of gelatin as a protective reagent by using hydrazine monohydrate as a reducing agent. The formed particles with the size between 190-940 nm were secondary aggregated particles which were composed of smaller nanosized particles ("particle-in-particle"), the presence of which was established by XRD patterns and a cross-sectional TEM image. The sintering behavior of these copper/gelatin composite particles was demonstrated by in-situ heating TEM under a high vacuum (approximately 10(-5) Pa) and separately with the oxygen partial pressure controlled at the 10(-4) Pa level. It was established that the particles began to sinter at about 330 degrees C with the oxygen and that they sublimate above 450 degrees C both in the vacuum and oxygen conditions. This result shows that the introduction of an adequate amount of oxygen was effective to remove the gelatin surrounding the particles. It can also be concluded that the sintering of the copper/gelatin composite particles occurred even in the absence of a reducing agent such as hydrogen gas.

  6. In situ one-pot synthesis of graphene–polyaniline nanofiber composite for high-performance electrochemical capacitors

    International Nuclear Information System (INIS)

    Jin, Yuhong; Fang, Mou; Jia, Mengqiu

    2014-01-01

    In this work, graphene–polyaniline nanofiber (G/PANI-F) composite is prepared through a new and one-pot method that includes the reduction of graphene oxide (GO) by aniline and then followed by in-situ polymerization. Aniline plays the two roles in this method: as a chemical reducing agent to reduce GO to graphene and as a monomer to prepare polyaniline nanofiber (PANI-F). Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy and transmission electron microscopy are employed to confirm that GO can be reduced by aniline and PANI-F can be deposited on the surface of graphene. The electrochemical properties of G/PANI-F composite electrode are measured by using cyclic voltammetry, galvanostatic charge–discharge test and electrochemical impedance spectroscopy. The G/PANI-F composite electrode exhibits enhanced specific capacitance of 965 F g −1 at 0.5 A g −1 and the capacity retention is 90% after 2000 cycles.

  7. Microstructure and properties of copper composite containing in situ NbC reinforcement: Effects of milling speed

    International Nuclear Information System (INIS)

    Zuhailawati, Hussain; Salihin, Hassin Mohd; Mahani, Yusoff

    2010-01-01

    This paper presents a study on the effects of milling speed on the properties of in situ copper-based composite produced by mechanical alloying followed by cold pressing and sintering. A powdered mixture of copper, niobium and graphite with the composition of Cu-30%NbC was milled at various speeds (100, 200, 300 and 400 rpm). The NbC phase started to precipitate in the as-milled powder after 30 h milling at 400 rpm and the formation was completed after sintering at 950 o C. Enhancements of NbC phase formation with a reduction in Cu crystallite size were observed with the increase of milling speed. Density, hardness and electrical conductivity of the sintered composite were evaluated. An increase in milling speed resulted in an increase in sintered density and hardness but a reduction of electrical conductivity. The changes in the properties were correlated to the formation of NbC phase and refinement of copper and niobium carbide crystallite size since higher milling speed is associated with higher kinetic energy per hit.

  8. Development of in-Situ Al-Si/CuAl2 Metal Matrix Composites: Microstructure, Hardness, and Wear Behavior

    Directory of Open Access Journals (Sweden)

    Mahmoud M. Tash

    2016-06-01

    Full Text Available In the present work, in-situ metal matrix composites were fabricated through squeeze casting. The copper particles were dispersed with different weight percentages (3%, 6%, 10%, and 15% into Al-12% Si piston alloy. Also, heat treatments were performed at 380 °C and 450 °C for holding times of 6 and 18 h. The microstructures, X-ray diffractometer (XRD pattern, hardness, and wear characteristics were evaluated. The results showed that these copper particles have reacted with the aluminum under all of the aforementioned processing conditions resulting in the formation of fine copper aluminide intermetallics. Most of the intermetallics were CuAl2, while AlCu appeared in a small ratio. Additionally, these intermetallics were homogenously distributed within the alloy matrix with up to 6% Cu addition. The amounts of those intermetallics increased after performing heat treatment. Most of these intermetallics were CuAl2 at 380 °C, while the Cu-rich intermetallics appeared at 450 °C. Increasing the holding time to 18 h, however, led to grain coarsening and resulted in the formation of some cracks. The hardness of the resulting composite materials was improved. The hardness value reached to about 170 HV after heat treating at 380 °C for 8 h. The wear resistance of the resulting composite materials was remarkably improved, especially at lower additions of Cu and at the lower heat treatment temperature.

  9. In situ synthesis of NiAl–NbB2 composite powder through combustion synthesis

    International Nuclear Information System (INIS)

    Shokati, Ali Akbar; Parvin, Nader; Sabzianpour, Naser; Shokati, Mohammad; Hemmati, Ali

    2013-01-01

    Highlights: ► A Novel NiAl matrix composite powder with 0–40 wt.% NbB 2 was synthesized. ► Composite powders were synthesized by thermal explosion reaction of Ni–Al–Nb–B system. ► Microhardness of NiAl considerably increased with raising NbB 2 content. ► Synthesized composite powders is a good candidate as precursor for thermal barrier application. - Abstract: Synthesis of a novel NiAl matrix composite powder reinforced with 0–40 wt.% NbB 2 by combustion synthesis in thermal explosion mode was investigated. The elemental powders of Ni, Al, Nb, and amorphous boron were used as starting material. For all compositions final products consisted of only the NiAl and NbB 2 phases. Coarser NbB 2 with a relatively uniform distribution in NiAl matrix was formed with rising NbB 2 content. Microhardness of NiAl considerably increased from 377 ± 13 HV 0.05 to 866 ± 81 HV 0.05 for NiAl with 40 wt.% NbB 2 . High microhardness, proper size and distribution of NbB 2 in NiAl matrix make it a good candidate as precursor for thermal spray application.

  10. Characteristics of solder joints under fatigue loads using piezomechanical actuation

    Science.gov (United States)

    Shim, Dong-Jin; Spearing, S. Mark

    2003-07-01

    Crack initiation and growth characteristics of solder joints under fatigue loads are investigated using piezomechanical actuation. Cracks in solder joints, which can cause failure in microelectronics components, are induced via piezoelectricity in piezo-ceramic bonded joints. Lead-zirconate-titanate ceramic plates and eutectic Sn-Pb solder bonded in a double-lap shear configuration are used in the investigation. Electric field across each piezo-ceramic plate is applied such that shear stresses/strains are induced in the solder joints. The experiments show that cracks initiate in the solder joints around defects such as voids and grow in length until they coalesce with other cracks from adjacent voids. These observations are compared with the similar thermal cycling tests from the literature to show feasibility and validity of the current method in investigating the fatigue characteristics of solder joints. In some specimens, cracks in the piezo-ceramic plates are observed, and failure in the specimens generally occurred due to piezo-ceramic plate fracture. The issues encountered in implementing this methodology such as low actuation and high processing temperatures are further discussed.

  11. Laser Soldering of Rat Skin Using a Controlled Feedback System

    Directory of Open Access Journals (Sweden)

    Mohammad Sadegh Nourbakhsh

    2009-03-01

    Full Text Available Introduction: Laser tissue soldering using albumin and indocyanine green dye (ICG is an effective technique utilized in various surgical procedures. The purpose of this study was to perform laser soldering of rat skin under a feedback control system and compare the results with those obtained using standard sutures. Material and Methods: Skin incisions were made over eight rats’ dorsa, which were subsequently closed using different wound closure interventions in two groups: (a using a temperature controlled infrared detector or (b by suture. Tensile strengths were measured at 2, 5, 7 and 10 days post-incision. Histological examination was performed at the time of sacrifice. Results: Tensile strength results showed that during the initial days following the incisions, the tensile strengths of the sutured samples were greater than the laser samples. However, 10 days after the incisions, the tensile strengths of the laser soldered incisions were higher than the sutured cuts. Histopathological examination showed a preferred wound healing response in the soldered skin compared with the control samples. The healing indices of the laser soldered repairs (426 were significantly better than the control samples (340.5. Conclusion: Tissue feedback control of temperature and optical changes in laser soldering of skin leads to a higher tensile strength and better histological results and hence this method may be considered as an alternative to standard suturing.

  12. Tensile strength of two soldered alloys (Minalux and Verabond2

    Directory of Open Access Journals (Sweden)

    Mir Mohammad Rezaee S

    2002-07-01

    Full Text Available Recently. Minalux alloy, a base metal free from Be, has been presented on the market while no special soldering has been recommended for it. On the other hand, based on the manufacturer's claim, this alloy is similar to Verabond2. The aim of this study was to investigate the tensile strength of Minalux and Verabond2, soldered by Verasolder. Twelve standard dambble shape samples, with the length of 18 mm and the diameter of 3mm, were prepared from each alloy. Six samples of each alloy were divided into two pieces with carboradom disk. Soldering gap distance was 0.3mm, measured by a special jig and they were soldered by Verasolder alloy. Six other samples, of both Iranian and foreign unsoldered alloys were considered as control group. Then samples were examined under tensile force and their tensile strength was recorded. Two- way variance analysis showed that the tensile strength of Minalux alloy and Verabond2 were not statistically significant (Verasoler 686, Minalux 723, but after soldering, such difference became significant (Minalux 308, Verabond2 432. Verabond2 showed higher tensile strength after soldering.

  13. Control of microstructure in soldered, brazed, welded, plated, cast or vapor deposited manufactured components

    Science.gov (United States)

    Ripley, Edward B.; Hallman, Russell L.

    2015-11-10

    Disclosed are methods and systems for controlling of the microstructures of a soldered, brazed, welded, plated, cast, or vapor deposited manufactured component. The systems typically use relatively weak magnetic fields of either constant or varying flux to affect material properties within a manufactured component, typically without modifying the alloy, or changing the chemical composition of materials or altering the time, temperature, or transformation parameters of a manufacturing process. Such systems and processes may be used with components consisting of only materials that are conventionally characterized as be uninfluenced by magnetic forces.

  14. Laboratory studies of the properties of in-situ burn residues: chemical composition of residues

    International Nuclear Information System (INIS)

    Trudel, B.K.; Buist, I.A.; Schatzke, D.; Aurand, D.

    1996-01-01

    The chemical composition of the residue from small-scale burns of thick oil slicks was studied. The objective was to describe the changes in chemical composition in oils burning on water and to determine how these changes were influenced by the condition of the burn. Small-scale test burns involved burning 40-cm diameter pools of oil on water. A range of eight oil types including seven crude oils and an automotive diesel were burned. For each oil, slicks of fresh oil of three different thicknesses were tested. Two of the oils were tested before and after weathering. Results showed that the composition of the residue differed greatly from the parent oil. Asphaltenes, high-boiling-point aromatics and resins remained concentrated in the burn residue. The burning of slicks appeared to remove most of the lower-molecular weight aromatic hydrocarbons which included the more toxic and more bioavailable components of the crude oils. 11 refs., 6 tabs

  15. The Mg{sub 2}Si phase evolution during thermomechanical processing of in-situ aluminum matrix macro-composite

    Energy Technology Data Exchange (ETDEWEB)

    Shafieizad, A.H. [The Complex Laboratory of Hot Deformation & Thermomechanical Processing of High Performance Engineering Materials, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Zarei-Hanzaki, A., E-mail: Zareih@ut.ac.ir [The Complex Laboratory of Hot Deformation & Thermomechanical Processing of High Performance Engineering Materials, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Abedi, H.R. [The Complex Laboratory of Hot Deformation & Thermomechanical Processing of High Performance Engineering Materials, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Al-Fadhalah, K.J. [Department of Mechanical Engineering, College of Engineering & Petroleum, Kuwait University, P.O. Box 5969, Safat 13060 (Kuwait)

    2015-09-17

    The microstructure and flow stress behavior of thermomechanically processed Al–Cu/Mg{sub 2}Si in-situ composite was studied emphasizing the evolution of primary and secondary reinforcement phases. Toward this end, the hot compression tests were conducted over the wide range of temperature (300–500 °C) and strain rate (0.001–0.1 s{sup −1}). Both the temperature and strain rate are found to possess a significant effect on the microstructural characteristics where a considerable softening is identified specially at low temperature regime. Besides the occurrence of restoration processes (mainly particle stimulated nucleation) the dynamic evolution of the reinforcements is introduced as the main factors affecting the reported softening. In this regard, the mechanical fragmentation, thermal disintegration, micro-buckling, coalescence and spheroidization of the primary and secondary particles are quantitatively and qualitatively addressed through a comprehensive scanning electron microscopy studies.

  16. Application of in situ current normalized PIGE method for determination of total boron and its isotopic composition

    International Nuclear Information System (INIS)

    Chhillar, Sumit; Acharya, R.; Sodaye, S.; Pujari, P.K.

    2014-01-01

    A particle induced gamma-ray emission (PIGE) method using proton beam has been standardized for determination of isotopic composition of natural boron and enriched boron samples. Target pellets of boron standard and samples were prepared in cellulose matrix. The prompt gamma rays of 429 keV, 718 keV and 2125 keV were measured from 10 B(p,αγ) 7 Be, 10 B(p, p'γ) 10 B and 11 B(p, p'γ) 11 B nuclear reactions, respectively. For normalizing the beam current variations in situ current normalization method was used. Validation of method was carried out using synthetic samples of boron carbide, borax, borazine and lithium metaborate in cellulose matrix. (author)

  17. Preparation of poly (methyl methacrylate)/nanometer calcium carbonate composite by in-situ emulsion polymerization

    Institute of Scientific and Technical Information of China (English)

    史建明; 包永忠; 黄志明; 翁志学

    2004-01-01

    Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.

  18. Polymethyl methacrylate and polystyrene with layered double hydroxide nano composites: In situ synthesis, morphology and thermal properties

    International Nuclear Information System (INIS)

    Botan, Rodrigo; Nogueira, Telma R.; Lona, Liliane M.F.; Wypych, Fernando

    2011-01-01

    Over the past decade, polymer nanocomposites have attracted interest, both in industry and in academia, because they often exhibit remarkable improvement in their properties when compared with pure polymer or conventional micro and macro-composites using low levels of reinforcements. In this work polymethyl methacrylate and polystyrene reinforced with layered double hydroxide, which was intercalated with sodium dodecyl sulfate were synthesized by in situ bulk polymerization. The nanocomposites were characterized and compared by X-ray diffraction, thermogravimetric analysis and flammability test. The X-ray diffraction demonstrated that synthesized nanocomposites showed a high global dispersion of layered double hydroxide, suggesting exfoliated morphology. The result of thermogravimetric analysis and flammability test for synthesized polystyrene/ layered double hydroxide nanocomposite presented a significant improvement in thermal stability and flammability property when compared with pure polymer. (author)

  19. Features of Pd-Ni-Fe solder system for vacuum brazing of low alloy steels

    International Nuclear Information System (INIS)

    Radzievskij, V.N.; Kurochko, R.S.; Lotsmanov, S.N.; Rymar', V.I.

    1975-01-01

    The brazing solder of the Pd-Ni-Fe alloyed with copper and lithium, in order to decrease the melting point and provide for a better spreading, when soldered in vacuum ensures a uniform strength of soldered joints with the base metal of low-alloyed steels of 34KHNIM-type. The properties of low-alloyed steel joints brazed with the Pd-Ni-Fe-system solder little depend on the changes in the soldering parameters. The soldered joint keeps a homogeneous structure after all the stages of heat treatment (annealing, quenching and tempering)

  20. Aging behavior of an in-situ TiB{sub 2}/Al-Cu-Li-x matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yanwei; Hong, Tianran; Geng, Jiwei; Han, Gaoyang; Chen, Dong; Li, Xianfeng, E-mail: brucelee75cn@sjtu.edu.cn; Wang, Haowei

    2017-02-15

    Transmission electron microscopy, differential scanning calorimetry and hardness tests have been performed on an in-situ TiB{sub 2}/Al-3.3Cu-1.0Li-0.60Mg-0.40Ag-0.14Zr-0.13Si composite to study its aging behavior at 175 °C. A cubic phase suspected to be the σ (Al{sub 5}Cu{sub 6}Mg{sub 2}) phase or its variant is precipitated at all aging stages studied, and this phase is not typically observed in the Al-Cu-Li alloys. The primary hardening (aging for 3 h) phases consist of δ′ (Al{sub 3}Li), β′ (Al{sub 3}Zr) and the cubic phase. After aging for 18 h, all precipitates including T{sub 1} (Al{sub 2}CuLi), S (Al{sub 2}CuMg), θ′ (Al{sub 2}Cu), δ′, β′ and the cubic phase have appeared, and the formation of T{sub 1} and S results in a rapid increase in hardness. With prolonging of aging time, the apparent coarsening of T{sub 1} and S results in a decline in hardness. - Highlights: •The aging behavior of an in-situ TiB{sub 2}/Al-Cu-Li-x composite was studied. •A cubic phase suspected to be σ (Al{sub 5}Cu{sub 6}Mg{sub 2}) or its variant was precipitated. •The hardness change was dominated by the evolution of T{sub 1} (Al{sub 2}CuLi) and S (Al{sub 2}CuMg).

  1. Aging behavior of an in-situ TiB2/Al-Cu-Li-x matrix composite

    International Nuclear Information System (INIS)

    Shen, Yanwei; Hong, Tianran; Geng, Jiwei; Han, Gaoyang; Chen, Dong; Li, Xianfeng; Wang, Haowei

    2017-01-01

    Transmission electron microscopy, differential scanning calorimetry and hardness tests have been performed on an in-situ TiB 2 /Al-3.3Cu-1.0Li-0.60Mg-0.40Ag-0.14Zr-0.13Si composite to study its aging behavior at 175 °C. A cubic phase suspected to be the σ (Al 5 Cu 6 Mg 2 ) phase or its variant is precipitated at all aging stages studied, and this phase is not typically observed in the Al-Cu-Li alloys. The primary hardening (aging for 3 h) phases consist of δ′ (Al 3 Li), β′ (Al 3 Zr) and the cubic phase. After aging for 18 h, all precipitates including T 1 (Al 2 CuLi), S (Al 2 CuMg), θ′ (Al 2 Cu), δ′, β′ and the cubic phase have appeared, and the formation of T 1 and S results in a rapid increase in hardness. With prolonging of aging time, the apparent coarsening of T 1 and S results in a decline in hardness. - Highlights: •The aging behavior of an in-situ TiB 2 /Al-Cu-Li-x composite was studied. •A cubic phase suspected to be σ (Al 5 Cu 6 Mg 2 ) or its variant was precipitated. •The hardness change was dominated by the evolution of T 1 (Al 2 CuLi) and S (Al 2 CuMg).

  2. Lead-free solder technology transfer from ASE Americas

    Energy Technology Data Exchange (ETDEWEB)

    FTHENAKIS,V.

    1999-10-19

    To safeguard the environmental friendliness of photovoltaics, the PV industry follows a proactive, long-term environmental strategy involving a life-of-cycle approach to prevent environmental damage by its processes and products from cradle to grave. Part of this strategy is to examine substituting lead-based solder on PV modules with other solder alloys. Lead is a toxic metal that, if ingested, can damage the brain, nervous system, liver and kidneys. Lead from solder in electronic products has been found to leach out from municipal waste landfills and municipal incinerator ash was found to be high in lead also because of disposed consumer electronics and batteries. Consequently, there is a movement in Europe and Japan to ban lead altogether from use in electronic products and to restrict the movement across geographical boundaries of waste containing lead. Photovoltaic modules may contain small amounts of regulated materials, which vary from one technology to another. Environmental regulations impact the cost and complexity of dealing with end-of-life PV modules. If they were classified as hazardous according to Federal or State criteria, then special requirements for material handling, disposal, record-keeping and reporting would escalate the cost of decommissioning the modules. Fthenakis showed that several of today's x-Si modules failed the US-EPA Toxicity Characteristic Leaching Procedure (TCLP) for potential leaching of Pb in landfills and also California's standard on Total Threshold Limit Concentration (TTLC) for Pb. Consequently, such modules may be classified as hazardous waste. He highlighted potential legislation in Europe and Japan which could ban or restrict the use of lead and the efforts of the printed-circuit industries in developing Pb-free solder technologies in response to such expected legislation. Japanese firms already have introduced electronic products with Pb-free solder, and one PV manufacturer in the US, ASE Americas has used a

  3. Synthesis and characterization of polypropylene/graphite nano composite preparation for in situ polymerization

    International Nuclear Information System (INIS)

    Montagna, L.S.; Fim, F. de C.; Galland, G.B.

    2010-01-01

    This paper presents the synthesis of polypropylene/graphite nanocomposites through in situ polymerization, using the metallocene catalyst C 20 H 16 Cl 2 Zr (dichloro(rac-ethylenebis(indenyl))zircon(IV)). The graphite nanosheets in nano dimensions were added to the polymer matrix in percentages of 0.6;1.0;4.2;4.8 and 6.0% (w/w). The TEM images indicated that the thickness of graphite nanosheets ranged from 4 to 60 nm and by means of XRD analysis it was observed that the physical and chemical treatment did not destroyed the graphite layers. The presence of nanosheets did not decrease the catalytic activity of the nanocomposites. TEM images and XRD analysis of nanocomposites showed a good dispersion of the graphite nanosheets in the polypropylene matrix. (author)

  4. In Situ Elevated Temperature Testing of Fly Ash Based Geopolymer Composites

    Science.gov (United States)

    Vickers, Les; Pan, Zhu; Tao, Zhong; van Riessen, Arie

    2016-01-01

    In situ elevated temperature investigations using fly ash based geopolymers filled with alumina aggregate were undertaken. Compressive strength and short term creep tests were carried out to determine the onset temperature of viscous flow. Fire testing using the standard cellulose curve was performed. Applying a load to the specimen as the temperature increased reduced the temperature at which viscous flow occurred (compared to test methods with no applied stress). Compressive strength increased at the elevated temperature and is attributed to viscous flow and sintering forming a more compact microstructure. The addition of alumina aggregate and reduction of water content reduced the thermal conductivity. This led to the earlier onset and shorter dehydration plateau duration times. However, crack formation was reduced and is attributed to smaller thermal gradients across the fire test specimen. PMID:28773568

  5. In Situ Elevated Temperature Testing of Fly Ash Based Geopolymer Composites

    Directory of Open Access Journals (Sweden)

    Les Vickers

    2016-06-01

    Full Text Available In situ elevated temperature investigations using fly ash based geopolymers filled with alumina aggregate were undertaken. Compressive strength and short term creep tests were carried out to determine the onset temperature of viscous flow. Fire testing using the standard cellulose curve was performed. Applying a load to the specimen as the temperature increased reduced the temperature at which viscous flow occurred (compared to test methods with no applied stress. Compressive strength increased at the elevated temperature and is attributed to viscous flow and sintering forming a more compact microstructure. The addition of alumina aggregate and reduction of water content reduced the thermal conductivity. This led to the earlier onset and shorter dehydration plateau duration times. However, crack formation was reduced and is attributed to smaller thermal gradients across the fire test specimen.

  6. In-situ prepared polyaniline-silver composites: single- and two-step strategies

    Czech Academy of Sciences Publication Activity Database

    Bober, Patrycja; Stejskal, Jaroslav; Trchová, Miroslava; Prokeš, J.

    2014-01-01

    Roč. 122, 10 March (2014), s. 259-266 ISSN 0013-4686 R&D Projects: GA ČR(CZ) GA13-00270S Institutional support: RVO:61389013 Keywords : composites * conducting polymer * polyaniline Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.504, year: 2014

  7. In situ-growth of silica nanowires in ceramic carbon composites

    Directory of Open Access Journals (Sweden)

    Rahul Kumar

    2017-09-01

    Full Text Available An understanding of the processing and microstructure of ceramic–carbon composites is critical to development of these composites for applications needing electrically conducting, thermal shock resistant ceramic materials. In the present study green compacts of carbon ceramic composites were prepared either by slurry processing or dry powder blending of one or more of the three — clay, glass, alumina and carbon black or graphite. The dried green compacts were sintered at 1400 °C in flowing argon. The ceramic carbon composites except the ones without clay addition showed formation of silica nanowires. The silica nanowire formation was observed in both samples prepared by slip casting and dry powder compaction containing either carbon black or graphite. TEM micrographs showed presence of carbon at the core of the silica nanowires indicating that carbon served the role of a catalyst. Selected area electron diffraction (SAED suggested that the silica nanowires are amorphous. Prior studies have reported formation of silica nanowires from silicon, silica, silicon carbide but this is the first report ever on formation of silica nanowires from clay.

  8. Contribution of trace metals in structuring in situ macroinvertebrate community composition along a salinity gradient

    NARCIS (Netherlands)

    Peeters, E.T.H.M.; Gardeniers, J.J.P.; Koelmans, A.A.

    2000-01-01

    Macroinvertebrates were studied along a salinity gradient in the North Sea Canal, The Netherlands, to quantify the effect of trace metals (cadmium, copper, lead, zinc) on community composition. In addition, two methods for assessing metal bioavailability (normalizing metal concentrations on organic

  9. Composition of in situ burn residue as a function of weathering conditions

    DEFF Research Database (Denmark)

    Fritt-Rasmussen, Janne; Ascanius, Birgit Elkjær; Brandvik, Per Johan

    2013-01-01

    removed the light compounds eluting before C13. No effect from the prior weathering time or the different ice coverage was seen in the burn residue composition. The content of selected Poly Aromatic Hydrocarbons (PAHs) was determined and it was noted that the concentration of PAHs with more than 4 rings...

  10. Constitution of novel polyamic acid/polypyrrole composite films by in-situ electropolymerization

    International Nuclear Information System (INIS)

    Hess, Euodia H.; Waryo, Tesfaye; Sadik, Omowunmi A.; Iwuoha, Emmanuel I.; Baker, Priscilla G.L.

    2014-01-01

    The preparation and characterization of polyamic acid-polypyrrole (PAA/PPy) composite films are reported in this paper. The thin films were synthesized by electrochemical method from a solution containing controlled molar ratio of chemically synthesized polyamic acid (PAA) and pyrrole monomer. Homogenous films were obtained by incorporating PAA into electropolymerized polypyrrole (PPy) thin film. The concentration of PAA (1.37 × 10 −6 M) was kept fixed throughout the composite ratio analysis, whilst the concentration of PPy was varied from 1.90 × 10 −3 M to 9.90 × 10 −3 M. The PAA/PPy thin films were electrodeposited at a glassy carbon electrode (GCE) and characterized using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Atomic force microscopy (AFM), Scanning electron microscopy (SEM) and voltammetry. The composition that best represented the homogenous incorporation of PAA into PPy matrix was observed at a PAA/PPy ratio of 1: 4.13 × 10 −3 . This composite was observed to have two sets of coupled peaks with formal potential 99 mV and 567 mV respectively. The D e determined from cyclic voltammetry using the anodic peak currents were found to be twice as high (5.82 × 10 −4 cm 2 /s) compared to the D e calculated using the cathodic peak currents (2.60 × 10 −4 cm 2 /s), indicating that the composite favours anodic electron mobility. Surface morphology and spectroscopy data support the formation of a homogenous polymer blend at the synthesis ratio of 1: 4.13 × 10 −3

  11. FY 1998 report on the waste processing/recycling related technology, 'The R and D of lead-free solder standardization'; 1998 nendo haikibutsu shori recycle kanren gijutsu seika hokokusho. Namari free handa kikakuka nado kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    To reduce the environmental pollution caused by lead eluted from the electronic equipment waste, the R and D on lead-free solder were conducted and the results were summarized. As to the basic characteristics, the evaluation test method was studied in terms of the range of melting temperature, mechanical strength, wettability and joint strength, to select a uniform test method. As the lead-free solder, Sn-Ag alloys were mainly used and mixed in a combination of Cu, Bi and In. Changes in characteristics were made clear by adding trace elements such as Ge, Mn and P. Relating to the applied characteristics, in selection of solder materials, materials were selected for which evaluation of the commercialization is proceeded with from a viewpoint of promotion of commercialization. Concerning the experimental evaluation of characteristics of lead-free solder in mounted substrates, it was indicated that basically lead-free solder can be practically used. Further, it was indicated that the Sn-Ag-Cu-Bi system depends not on solder composition but on active force, printing accuracy and flux characteristic of solder paste, that improvement of solder paste has an effect on mounting characteristics. (NEDO)

  12. MICROSTRUCTURE, THERMO-PHYSICAL, MECHANICAL AND WEAR PROPERTIES OF IN-SITU FORMED BORON CARBIDE - ZIRCONIUM DIBORIDE COMPOSITE

    Directory of Open Access Journals (Sweden)

    T. S. R. Ch. Murthy

    2017-12-01

    Full Text Available Microstructure, thermos-physical, mechanical and wear properties of in-situ formed B₄C- ZrB₂ composite were investigated. Coefficient of thermal expansion, thermal diffusivity and electrical resistivity of the composite were measured at different temperatures up to 1000 °C in inert atmosphere. Flexural strength was measured up to 900 °C in air. Friction and wear properties have been studied at different loads under reciprocative sliding, using a counter body (ball of cemented tungsten carbide (WC-Co at ambient conditions. X-ray diffraction (XRD and electron probe microanalysis (EPMA confirmed the formation of ZrB₂ as the reaction product in the composite. Electrical resistivity was measured as 3.02 x 10-4Ω.m at 1000°C. Thermal conductivity measured at temperatures between 25°C and 1000 °C was in the range of 8 to 10 W/m-K. Flexural strength of the composite decreased with increase in temperature and reached a value of 92 MPa at 900°C. The average value of coefficient of friction (COF was measured as 0.15 at 20 N load and 10 Hz frequency. Increase of load from 5 N to 20 N resulted in decrease in COF from 0.24 to 0.15 at 10 Hz frequency. Specific wear rate data observed was of the order of 10-6 mm³/N-m. Both abrasive and tribo-chemical reaction wear mechanisms were observed on the worn surface of flat and counter body materials. At higher loads (≥10 N a tribo-chemical reaction wear mechanism was dominant.

  13. Characterizing the Soldering Alloy Type In–Ag–Ti and the Study of Direct Soldering of SiC Ceramics and Copper

    Directory of Open Access Journals (Sweden)

    Roman Koleňák

    2018-04-01

    Full Text Available The aim of the research was to characterize the soldering alloy In–Ag–Ti type, and to study the direct soldering of SiC ceramics and copper. The In10Ag4Ti solder has a broad melting interval, which mainly depends on its silver content. The liquid point of the solder is 256.5 °C. The solder microstructure is composed of a matrix with solid solution (In, in which the phases of titanium (Ti3In4 and silver (AgIn2 are mainly segregated. The tensile strength of the solder is approximately 13 MPa. The strength of the solder increased with the addition of Ag and Ti. The solder bonds with SiC ceramics, owing to the interaction between active In metal and silicon infiltrated in the ceramics. XRD analysis has proven the interaction of titanium with ceramic material during the formation of the new minority phases of titanium silicide—SiTi and titanium carbide—C5Ti8. In and Ag also affect bond formation with the copper substrate. Two new phases were also observed in the bond interphase—(CuAg6In5 and (AgCuIn2. The average shear strength of a combined joint of SiC–Cu, fabricated with In10Ag4Ti solder, was 14.5 MPa. The In–Ag–Ti solder type studied possesses excellent solderability with several metallic and ceramic materials.

  14. Effect of ultrasonic stirring on the microstructure and mechanical properties of in situ Mg{sub 2}Si/Al composite

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jixing, E-mail: linjixing@163.com [Department of Material Engineering, Zhejiang Industry & Trade Vocational College, Wenzhou 325003 (China); College of Materials Science and Engineering, Jilin University, Changchun 130000 (China); Bai, Guangzhu [Department of Material Engineering, Zhejiang Industry & Trade Vocational College, Wenzhou 325003 (China); School of Materials Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Liu, Zheng [School of Mechanical and Electrical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Niu, Liyuan [Department of Material Engineering, Zhejiang Industry & Trade Vocational College, Wenzhou 325003 (China); Li, Guangyu [College of Materials Science and Engineering, Jilin University, Changchun 130000 (China); Wen, Cuie [School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Melbourne, Victoria 3001 (Australia)

    2016-08-01

    In situ Mg{sub 2}Si/Al composites are receiving increasing attention for industrial applications because of their inherently stable interfaces, light weight, excellent combination of mechanical properties and low processing costs. The composite is formed through in situ nucleation and growth of a reinforcing phase Mg{sub 2}Si from the parent matrix during solidification. In this study, we report the effect of ultrasonic stirring with different times on the solidification structure and mechanical properties of in situ Mg{sub 2}Si/Al composites. X-ray diffraction analysis, optical microscopy and scanning electron microscopy were used to analyze the microstructural evolution of the composites. The mechanical properties of the composites were tested by using hardness and tensile testers. Our results showed that 40 s ultrasonic stirring resulted in the optimal impact on the refining both the primary and eutectic Mg{sub 2}Si particles and improving the shapes of the primary Mg{sub 2}Si particles. The composites with 40 s ultrasonic stirring exhibited simultaneously enhanced tensile strength and elongation and the tensile fracture morphology was shown to be quasi-cleavage with a large number of dimples. This study proves that ultrasonic stirring is effective in degassing, removal of impurities, refining, and improving the shapes of the reinforcing phase, leading to significantly enhance the mechanical performance of the composites. - Highlights: • Ultrasonic technique shows excellent impact during Al composite processing. • Ultrasonic stirring improves the shapes of Mg{sub 2}Si particles with higher circularity. • Ultrasonic stirring results in an increase in the tensile strength of the composite. • Ultrasonic stirring leads to a significantly increased elongation of the composite. • Tensile fracture of composite with ultrasonic stirring shows more ductile features.

  15. Kinetics of intermetallic phase formation at the interface of Sn-Ag-Cu-X (X = Bi, In) solders with Cu substrate

    International Nuclear Information System (INIS)

    Hodulova, Erika; Palcut, Marian; Lechovic, Emil; Simekova, Beata; Ulrich, Koloman

    2011-01-01

    Highlights: → In substitutes Sn in intermetallic compounds formed at the Cu-solder interface. → Bi and In decrease the parabolic rate constant of Cu 3 Sn layer growth. → In increases the parabolic rate constant of Cu 6 Sn 5 layer growth. → High In concentrations should be avoided since they may lead to a pre-mature solder joint degradation. - Abstract: The effects of Bi and In additions on intermetallic phase formation in lead-free solder joints of Sn-3.7Ag-0.7Cu; Sn-1.0Ag-0.5Cu-1.0Bi and Sn-1.5Ag-0.7Cu-9.5In (composition given in weight %) with copper substrate are studied. Soldering of copper plate was conducted at 250 deg. C for 5 s. The joints were subsequently aged at temperatures of 130-170 deg. C for 2-16 days in a convection oven. The aged interfaces were analyzed by optical microscopy and energy dispersive X-ray spectroscopy (EDX) microanalysis. Two intermetallic layers are observed at the interface - Cu 3 Sn and Cu 6 Sn 5 . Cu 6 Sn 5 is formed during soldering. Cu 3 Sn is formed during solid state ageing. Bi and In decrease the growth rate of Cu 3 Sn since they appear to inhibit tin diffusion through the grain boundaries. Furthermore, indium was found to produce a new phase - Cu 6 (Sn,In) 5 instead of Cu 6 Sn 5 , with a higher rate constant. The mechanism of the Cu 6 (Sn,In) 5 layer growth is discussed and the conclusions for the optimal solder chemical composition are presented.

  16. Developments of high strength Bi-containing Sn0.7Cu lead-free solder alloys prepared by directional solidification

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xiaowu, E-mail: xwhmaterials@aliyun.com [School of Mechanical Electrical Engineering, Nanchang University, Nanchang 330031 (China); Li, Yulong [School of Mechanical Electrical Engineering, Nanchang University, Nanchang 330031 (China); Liu, Yi [School of Materials Science and Engineering, Nanchang University, Nanchang 330031 (China); Min, Zhixian [China Electronics Technology Group Corporation No. 38 Research Institute, Hefei 230088 (China)

    2015-03-15

    Highlights: • The Sn0.7Cu–xBi solder alloys were directionally solidified. • Both spacing and diameter of fibers decreased with increasing solidification rate. • The UTS and YS first increased with increased solidification rate, then decreased. • The UTS and YS of Sn0.7Cu–xBi first increased with increased Bi content. - Abstract: Bi-containing Sn0.7Cu (SC) eutectic solder alloys were prepared and subjected to directional solidification, through which new types of fiber reinforced eutectic composites were generated. The influences of Bi addition on the microstructures and tensile properties of directionally solidified (DS) Bi-containing eutectic SC lead-free solder alloys have been investigated by using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and a tensile testing machine. The experimental results showed that addition of Bi could effectively reduce both the melting temperature and undercooling of SC solder alloy. The microstructures of DS SC–xBi solder alloys were composed of Sn-rich phase (β) and Cu{sub 6}Sn{sub 5} fiber. No other intermetallic compounds (IMCs) with Bi content were observed in the solder matrix for SC solder alloys with various Bi contents. Both fiber spacing and diameter all decreased gradually with increasing growth rate and/or Bi content. Besides, the regularity of Cu{sub 6}Sn{sub 5} fibers alignment also decreased with increasing growth rate, too. The tensile strengths of the SC–xBi eutectic solder alloys varied parabolically with growth rate (R). When R was 60 μm/s, maximum tensile strengths of 43.8, 55.2 and 56.37 MPa were reached for SC, SC0.7Bi and SC1.3Bi solder alloys. A comparison of tensile strength of SC, SC0.7Bi and SC1.3Bi with the same R indicated that the tensile strength increased with increasing Bi content, which was attributed to the presence of Bi and its role in refining microstructure and solid solution strengthening.

  17. Advancement in conductive cotton fabrics through in situ polymerization of polypyrrole-nanocellulose composites.

    Science.gov (United States)

    Hebeish, A; Farag, S; Sharaf, S; Shaheen, Th I

    2016-10-20

    Current research was undertaking with a view to innovate a new approach for development of conductive - coated textile materials through coating cotton fabrics with nanocellulose/polypyrrole composites. The study was designed in order to have a clear understanding of the role of nanocellulose as well as modified composite thereof under investigation. It is anticipated that incorporation of nanocellulose in the pyrrole/cotton fabrics/FeCl3/H2O system would form an integral part of the composites with mechanical, electrical or both properties. Three different nanocellulosic substrates are involved in the oxidation polymerization reaction of polypyrrole (Ppy) in presence of cotton fabrics. Polymerization was subsequently carried out by admixing at various ratios of FeCl3 and pyrrole viz. Ppy1, Ppy2 and pp3. The conductive, mechanical and thermal properties of cotton fabrics coated independently with different nanocellulose/polypyrrole were investigated. FTIR, TGA, XRD, SEM and EDX were also used for further characterization. Results signify that, the conductivity of cotton fabrics increases exponentially with increasing the dose of pyrrole and oxidant irrespective of nanocellulose substrate used. While, the mechanical properties of cotton fabrics are not significantly affected by the oxidant treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. In-Situ NDE Characterization of Kevlar and Carbon Composite Micromechanics for Improved COPV Health Monitoring

    Science.gov (United States)

    Waller, Jess M.; Saulsberry, Regor L.

    2009-01-01

    This project is a subtask of a multi-center project to advance the state-of-the-art by developing NDE techniques that are capable of evaluating stress rupture (SR) degradation in Kevlar/epoxy (K/Ep) composite overwrapped pressure vessels (COPVs), and damage progression in carbon/epoxy (C/Ep) COPVs. In this subtask, acoustic emission (AE) data acquired during intermittent load hold tensile testing of K/Ep and C/Ep composite tow materials-of-construction used in COPV fabrication were analyzed to monitor progressive damage during the approach to tensile failure. Insight into the progressive damage of composite tow was gained by monitoring AE event rate, energy, source location, and frequency. Source location based on arrival time data was used to discern between significant AE attributable to microstructural damage and spurious AE attributable to background and grip noise. One of the significant findings was the observation of increasing violation of the Kaiser effect (Felicity ratio < 1.0) with damage accumulation.

  19. In-situ caustic generation from sewage: the impact of caustic strength and sewage composition.

    Science.gov (United States)

    Pikaar, Ilje; Rozendal, René A; Rabaey, Korneel; Yuan, Zhiguo

    2013-10-01

    Periodic caustic dosage is a commonly used method by the water industry to elevate pH levels and deactivate sewer biofilms responsible for hydrogen sulfide generation. Caustic (NaOH) can be generated in-situ from sewage using a divided electrochemical cell, which avoids the need for transport, handling and storage of concentrated caustic solutions. In this study, we investigated the impact of caustic strength in the cathode compartment and the impact of sodium concentration in sewage on the Coulombic efficiency (CE) for caustic generation. The CE was found to be independent of the caustic strength produced in the range of up to ~3 wt%. Results showed that a caustic solution of ~3 wt% could be produced directly from sewage at a CE of up to 75 ± 0.5%. The sodium concentration in sewage had a significant impact on the CE for caustic generation as well as on the energy requirements of the system, with a higher sodium concentration leading to a higher CE and lower energy consumption. The proton, calcium, magnesium and ammonium concentrations in sewage affected the CE for caustic generation, especially at low sodium concentrations. Economical assessment based on the experimental results indicated that sulfide control in sewers using electrochemically-generated caustic from sewage is an economically attractive strategy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. In situ electron microscopy of Braille microsystems: photo-actuation of ethylene vinyl acetate/carbon nanotube composites

    Science.gov (United States)

    Czaniková, Klaudia; Krupa, Igor; Račko, Dušan; Šmatko, Vasilij; Campo, Eva M.; Pavlova, Ewa; Omastová, Mária

    2015-02-01

    The development of new types of tactile displays based on the actuation of composite materials can aid the visually impaired. Micro/nano systems based on ethylene vinyl acetate (EVA) polymeric matrices enriched with multiwalled carbon nanotubes (MWCNT) can produce ensembles capable of light-induced actuation. In this report, we investigate two types of commercial EVA copolymers matrices containing 28 and 50 wt% vinyl-acetate (VA). Non-covalent modification of carbon nanotubes was achieved through a compatibilization technique that appends the pyrenenyl and cholesteryl groups on the carbon nanotubes (CNTs) surface. EVA/MWCNT nanocomposites were prepared by casting from a solution. These composites were shaped into Braille elements using molds. The deformation of the Braille element (BE) under light-emitting diode (LED) illumination was observed for the first time by in situ scanning electron microscopy (SEM). The superior actuation performance promoted by the EVA/MWCNT nanocomposites indicates that these materials will be useful in the future as light-driven micro/nano system actuators.

  1. In situ electron microscopy of Braille microsystems: photo-actuation of ethylene vinyl acetate/carbon nanotube composites

    International Nuclear Information System (INIS)

    Czaniková, Klaudia; Krupa, Igor; Račko, Dušan; Omastová, Mária; Šmatko, Vasilij; Campo, Eva M; Pavlova, Ewa

    2015-01-01

    The development of new types of tactile displays based on the actuation of composite materials can aid the visually impaired. Micro/nano systems based on ethylene vinyl acetate (EVA) polymeric matrices enriched with multiwalled carbon nanotubes (MWCNT) can produce ensembles capable of light-induced actuation. In this report, we investigate two types of commercial EVA copolymers matrices containing 28 and 50 wt% vinyl-acetate (VA). Non-covalent modification of carbon nanotubes was achieved through a compatibilization technique that appends the pyrenenyl and cholesteryl groups on the carbon nanotubes (CNTs) surface. EVA/MWCNT nanocomposites were prepared by casting from a solution. These composites were shaped into Braille elements using molds. The deformation of the Braille element (BE) under light-emitting diode (LED) illumination was observed for the first time by in situ scanning electron microscopy (SEM). The superior actuation performance promoted by the EVA/MWCNT nanocomposites indicates that these materials will be useful in the future as light-driven micro/nano system actuators. (paper)

  2. Microstructure and mechanical properties of diffusion bonded Al/Mg2Si metal matrix in situ composite

    International Nuclear Information System (INIS)

    Nami, H.; Halvaee, A.; Adgi, H.; Hadian, A.

    2010-01-01

    In this research, Al/Mg 2 Si composite produced by gravity casting, was joined by diffusion welding technique at 6 MPa pressure with various welding temperatures and durations. This metal matrix composite (MMC) containing 15% Mg 2 Si particles was produced by in situ technique. Specific diffusion bonding process was introduced as a low vacuum technique. Microstructure and shear strength of the joined areas were determined. Scanning electron microscopy examination was carried out on the welded interfaces and shear tests were conducted to the samples interface to find out the effect of welding temperatures and durations on the weldability. It was found that high welding temperatures resulted in increase of shear strength. However, increase in welding duration did not make any detectable changes. The bonded interface could be developed as a wavy state depending on the amount of parent material deformation that was associated with bonding temperature. Results indicated that MMC can be joined by diffusion welding technique successfully with satisfactory shear strength.

  3. Experimental and Thermodynamic Study of Selected in-Situ Composites from the Fe-Cr-Ni-Mo-C System

    Directory of Open Access Journals (Sweden)

    Wieczerzak K.

    2016-06-01

    Full Text Available The aim of the study was to synthesize and characterize the selected in-situ composites from the Fe-Cr-Ni-Mo-C system, additionally strengthened by intermetallic compounds. The project of the alloys was supported by thermodynamic simulations using Calculation of Phase Diagram approach via Thermo-Calc. Selected alloys were synthesized in an arc furnace in a high purity argon atmosphere using a suction casting unit. The studies involved a range of experimental techniques to characterize the alloys in the as-cast state, including optical emission spectrometry, light microscopy, scanning electron microscopy, electron microprobe analysis, X-ray diffraction and microhardness tests. These experimental studies were compared with the Thermo-Calc data and high resolution dilatometry. The results of investigations presented in this paper showed that there is a possibility to introduce intermetallic compounds, such as χ and σ, through modification of the chemical composition of the alloy with respect to Nieq and Creq. It was found that the place of intermetallic compounds precipitation strongly depends on matrix nature. Results presented in this paper may be successfully used to build a systematic knowledge about the group of alloys with a high volume fraction of complex carbides, and high physicochemical properties, additionally strengthened by intermetallic compounds.

  4. Tuning of colossal dielectric constant in gold-polypyrrole composite nanotubes using in-situ x-ray diffraction techniques

    Directory of Open Access Journals (Sweden)

    Abhisakh Sarma

    2014-09-01

    Full Text Available In-situ x-ray diffraction technique has been used to study the growth process of gold incorporated polypyrrole nanotubes that exhibit colossal dielectric constant due to existence of quasi-one-dimensional charge density wave state. These composite nanotubes were formed within nanopores of a polycarbonate membrane by flowing pyrrole monomer from one side and mixture of ferric chloride and chloroauric acid from other side in a sample cell that allows collection of x-ray data during the reaction. The size of the gold nanoparticle embedded in the walls of the nanotubes was found to be dependent on chloroauric acid concentration for nanowires having diameter more than 100 nm. For lower diameter nanotubes the nanoparticle size become independent of chloroauric acid concentration and depends on the diameter of nanotubes only. The result of this study also shows that for 50 nm gold-polypyrrole composite nanotubes obtained with 5.3 mM chloroauric acid gives colossal dielectric constant of about 107. This value remain almost constant over a frequency range from 1Hz to 106 Hz even at 80 K temperature.

  5. Tuning of colossal dielectric constant in gold-polypyrrole composite nanotubes using in-situ x-ray diffraction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Sarma, Abhisakh; Sanyal, Milan K., E-mail: milank.sanyal@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)

    2014-09-15

    In-situ x-ray diffraction technique has been used to study the growth process of gold incorporated polypyrrole nanotubes that exhibit colossal dielectric constant due to existence of quasi-one-dimensional charge density wave state. These composite nanotubes were formed within nanopores of a polycarbonate membrane by flowing pyrrole monomer from one side and mixture of ferric chloride and chloroauric acid from other side in a sample cell that allows collection of x-ray data during the reaction. The size of the gold nanoparticle embedded in the walls of the nanotubes was found to be dependent on chloroauric acid concentration for nanowires having diameter more than 100 nm. For lower diameter nanotubes the nanoparticle size become independent of chloroauric acid concentration and depends on the diameter of nanotubes only. The result of this study also shows that for 50 nm gold-polypyrrole composite nanotubes obtained with 5.3 mM chloroauric acid gives colossal dielectric constant of about 10{sup 7}. This value remain almost constant over a frequency range from 1Hz to 10{sup 6} Hz even at 80 K temperature.

  6. In situ studies of uranium-plutonium mixed oxides. Influence of composition on phase equilibria and thermodynamic properties

    International Nuclear Information System (INIS)

    Strach, Michal

    2015-01-01

    Due to their physical and chemical properties, mixed uranium-plutonium oxides are considered for fuel in 4. generation nuclear reactors. In this frame, complementary experimental studies are necessary to develop a better understanding of the phenomena that take place during fabrication and operation in the reactor. The focus of this work was to study the U-Pu-O phase diagram in a wide range of compositions and temperatures to ameliorate our knowledge of the phase equilibria in this system. Most of experiments were done using in situ X-ray diffraction at elevated temperatures. The control of the oxygen partial pressure during the treatments made it possible to change the oxygen stoichiometry of the sample, which gave us an opportunity to study rapidly different compositions and the processes involved. The experimental approach was coupled with thermodynamic modeling using the CALPHAD method, to precisely plan the experiments and interpret the obtained results. This approach enabled us to enhance the knowledge of phase equilibria in the U-Pu-O system. (author) [fr

  7. Ex-situ X-ray computed tomography data for a non-crimp fabric based glass fibre composite under fatigue loading

    DEFF Research Database (Denmark)

    Jespersen, Kristine Munk; Mikkelsen, Lars Pilgaard

    2017-01-01

    The data published with this article are high resolution X-ray computed tomography (CT) data obtained during an ex-situ fatigue test of a coupon test specimen made from a non-crimp fabric based glass fibre composite similar to those used for wind turbine blades. The fatigue test was interrupted...

  8. A New Design of In Situ Ti(C,N) Reinforced Composite Coatings and Their Microstructures, Interfaces, and Wear Resistances.

    Science.gov (United States)

    Wang, Mingliang; Cui, Hongzhi; Wei, Na; Ding, Lei; Zhang, Xinjie; Zhao, Yong; Wang, Canming; Song, Qiang

    2018-01-31

    Here, a unique combination of a novel carbon-nitrogen source (g-C 3 N 4 ) with different mole ratios of Ti/g-C 3 N 4 has been utilized to fabricate iron matrix composite coatings by a synchronized powder feeding plasma transferred arc (PTA) cladding technology. The results show that submicron Ti(C,N) particles are successfully fabricated in situ on a Q235 low carbon steel substrate to reinforce the iron matrix composite coatings and exhibit dense microstructures and good metallurgical bonding between the coating and the substrate. The microstructure of the coating consists of an α-Fe matrix and Ti(C,N) particles when the mole ratio of Ti/g-C 3 N 4 is no more than 5:1. The microhardness and wear resistance of the coating gradually improve with increasing abundance of the in-situ-synthesized Ti(C,N) particles. Interestingly, for a Ti/g-C 3 N 4 mole ratio of 6:1, a fine lamellar eutectic Laves phase (Fe 2 Ti) appears, and this phase further improves the microhardness and wear resistance of the coating. The microhardness of the coating is 3.5 times greater than that of the Q235 substrate, and the wear resistance is enhanced 7.66 times over that of the substrate. The Ti(C,N)/Fe 2 Ti and Fe 2 Ti/α-Fe interfaces are very clean, and the crystallographic orientation relationships between the phases are analyzed by high-resolution transmission electron microscopy (HRTEM) and an edge-to-edge matching model. The theoretical predictions and the experimental results are in good agreement. Furthermore, based on the present study, for the solidification process near equilibrium, smaller interatomic spacing misfits and interplanar spacing d-value mismatches contribute to the formation of crystallographic orientation relationships between phases during the PTA cladding process. The existence of orientation relationships is beneficial for improving the properties of the coatings. This work not only expands the application fields of g-C 3 N 4 but also provides a new idea for the

  9. Thermal decomposition of solder flux activators under simulated wave soldering conditions

    DEFF Research Database (Denmark)

    Piotrowska, Kamila; Jellesen, Morten Stendahl; Ambat, Rajan

    2017-01-01

    /methodology/approach: Changes in the chemical structure of the activators were studied using Fourier transform infrared spectroscopy technique and were correlated to the exposure temperatures within the range of wave soldering process. The amount of residue left on the surface was estimated using standardized acid-base...... titration method as a function of temperature, time of exposure and the substrate material used. Findings: The study shows that there is a possibility of anhydride-like species formation during the thermal treatment of fluxes containing weak organic acids (WOAs) as activators (succinic and DL...

  10. Mechanical properties of Bi-In-Zn/ Cu solder joint system

    International Nuclear Information System (INIS)

    Ervina Efzan Mohd Noor; Mohammed Noori Ridha; Ahmad Badri Ismail; Nurulakmal Mohd Sharif; Kuan Yew Cheong; Tadashi Ariga; Zuhailawati Hussain

    2009-01-01

    Full text: In recent years, the pollution of environment from lead (Pb) and Pb-containing compounds in microelectronic devices attracts more and more attentions in academia and industry; the lead-free solder alloys begin to replace the lead-based solders in packaging process of some devices and components. In this works, microstructure and mechanical properties of different reflow temperature (80, 100, 120 and 140 degree Celsius) for solder joints on shear strength of Bi-In-Zn lead free solder with low melting temperature of 60 degree Celsius on Cu solder joint has been investigated. This paper will compared the mechanical properties of the Bi-In-Zn lead-free solder alloys with current lead-free solder, Sn-Ag-Cu solder alloy. The fracture surface analyses have been observed by Optical Microscope and were investigated by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDX) and proved it by X-ray diffraction (XRD). (author)

  11. In situ chemical composition measurement of individual cloud residue particles at a mountain site, southern China

    Directory of Open Access Journals (Sweden)

    Q. Lin

    2017-07-01

    Full Text Available To investigate how atmospheric aerosol particles interact with chemical composition of cloud droplets, a ground-based counterflow virtual impactor (GCVI coupled with a real-time single-particle aerosol mass spectrometer (SPAMS was used to assess the chemical composition and mixing state of individual cloud residue particles in the Nanling Mountains (1690 m a. s. l. , southern China, in January 2016. The cloud residues were classified into nine particle types: aged elemental carbon (EC, potassium-rich (K-rich, amine, dust, Pb, Fe, organic carbon (OC, sodium-rich (Na-rich and Other. The largest fraction of the total cloud residues was the aged EC type (49.3 %, followed by the K-rich type (33.9 %. Abundant aged EC cloud residues that mixed internally with inorganic salts were found in air masses from northerly polluted areas. The number fraction (NF of the K-rich cloud residues increased within southwesterly air masses from fire activities in Southeast Asia. When air masses changed from northerly polluted areas to southwesterly ocean and livestock areas, the amine particles increased from 0.2 to 15.1 % of the total cloud residues. The dust, Fe, Pb, Na-rich and OC particle types had a low contribution (0.5–4.1 % to the total cloud residues. Higher fraction of nitrate (88–89 % was found in the dust and Na-rich cloud residues relative to sulfate (41–42 % and ammonium (15–23 %. Higher intensity of nitrate was found in the cloud residues relative to the ambient particles. Compared with nonactivated particles, nitrate intensity decreased in all cloud residues except for dust type. To our knowledge, this study is the first report on in situ observation of the chemical composition and mixing state of individual cloud residue particles in China.

  12. Microstructure Characteristic of In-situ Ti/TiC Composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    TiC reinforced titanium composites has been produced with different Al content and C content by XDTM. The results have shown that TiC particles are of two different morphologies: coarse dendritical primary TiC and short bar-shape eutectic TiC. Al content has great effects on the morphology of TiC. With the increasing of Al content, the morphology of primary TiC changes from coarse developed dendrite into short bar-shape or plate-shape TiC with 35%Al. Meanwhile, the structure of the matrix changes from single Ti to Ti and Ti3Al, and to Ti3Al and TiAl. However, the C content has no influence on the microstructure of matrix. When the C content is less than 1.2%, the dendrite TiC disappears and only short bar-shape or plate-shape TiC exists in the composites. In addition, the effect of heat treatment on the morphology of TiC has also studied.

  13. Dry Sliding Wear Behavior of A356 Alloy/Mg2Sip Functionally Graded in-situ Composites: Effect of Processing Conditions

    Directory of Open Access Journals (Sweden)

    S.C. Ram

    2016-09-01

    Full Text Available In present study, the effect of dry sliding wear conditions of A356 alloy/Mg2Sip functionally graded in-situ composites developed by centrifugal casting method has been studied. A pure commercial A356 alloy (Al–7.5Si–0.3Mg was selected to be the matrix of the composites and primary Mg2Sip reinforcing particles were formed by in-situ chemical reaction with an average grain size of 40-47.8 µm. The Al–(Mg2Sip functionally graded metal matrix composites (FGMMC’s were synthesized by centrifugal casting technique with radial geometry, using two different mould rotating speeds ( 1200 and 1600 rpm. The X-ray diffraction (XRD characterization technique was carried out to confirm the in-situ formed Mg2Si particles in composites. Optical microscopy examination was carried out to reveals the grain refinement of Al-rich grains due to in-situ formed Mg2Si particles. Scanning electron microscope (SEM and Energy dispersive X-ray spectroscopy (EDS techniques were carried out to reveal the distribution of phases, morphological characteristics and confirmation of primary Mg2Si particles in the matrix. The sliding wear behavior was studied using a Pin-on-Disc set-up machine with sliding wear parameters: effect of loads (N, effect of sliding distances (m and effect of Mg on wear at room temperature with a high-carbon chromium steel disc (HRC-64 as counter surfaces. A good correlation was evidenced between the dry sliding behaviour of functionally graded in-situ composites and the distribution of Mg2Si reinforcing particles. Beside the above processing conditions, the dominant wear mechanisms of functionally graded in-situ composites have been correlated with the microstructures. The hardness and wear resistance properties of these composites increase with increasing volume percent of reinforced primary Si/Mg2Si particles toward inner zone of cast cylindrical shapes. The objective of this works was to study the tribological characteristics under dry sliding

  14. In-Situ Nondestructive Evaluation of Kevlar(Registered Trademark)and Carbon Fiber Reinforced Composite Micromechanics for Improved Composite Overwrapped Pressure Vessel Health Monitoring

    Science.gov (United States)

    Waller, Jess; Saulsberry, Regor

    2012-01-01

    NASA has been faced with recertification and life extension issues for epoxy-impregnated Kevlar 49 (K/Ep) and carbon (C/Ep) composite overwrapped pressure vessels (COPVs) used in various systems on the Space Shuttle and International Space Station, respectively. Each COPV has varying criticality, damage and repair histories, time at pressure, and pressure cycles. COPVs are of particular concern due to the insidious and catastrophic burst-before-leak failure mode caused by stress rupture (SR) of the composite overwrap. SR life has been defined [1] as the minimum time during which the composite maintains structural integrity considering the combined effects of stress level(s), time at stress level(s), and associated environment. SR has none of the features of predictability associated with metal pressure vessels, such as crack geometry, growth rate and size, or other features that lend themselves to nondestructive evaluation (NDE). In essence, the variability or surprise factor associated with SR cannot be eliminated. C/Ep COPVs are also susceptible to impact damage that can lead to reduced burst pressure even when the amount of damage to the COPV is below the visual detection threshold [2], thus necessitating implementation of a mechanical damage control plan [1]. Last, COPVs can also fail prematurely due to material or design noncompliance. In each case (SR, impact or noncompliance), out-of-family behavior is expected leading to a higher probability of failure at a given stress, hence, greater uncertainty in performance. For these reasons, NASA has been actively engaged in research to develop NDE methods that can be used during post-manufacture qualification, in-service inspection, and in-situ structural health monitoring. Acoustic emission (AE) is one of the more promising NDE techniques for detecting and monitoring, in real-time, the strain energy release and corresponding stress-wave propagation produced by actively growing flaws and defects in composite

  15. Aging effects on the microstructure, surface characteristics and wettability of Cu pretinned with Sn-Pb solders

    Energy Technology Data Exchange (ETDEWEB)

    Linch, Heidi Sue [Univ. of California, Berkeley, CA (United States)

    1993-11-01

    This study investigates effects of aging in air and argon at 170 C on Cu coupons which were pretinned with 75Sn-25Pb, 8Sn-92Pb, and 5Sn-95Pb solders. Coatings were applied using electroplating or hot dipping techniques. The coating thickness was controlled between 3 to 3μm and the specimens were aged for 0 hours, 2 hours, 24 hours and 2 weeks. Wetting balance tests were used to evaluate the wettability of the test specimens. Microstructural development was evaluated using X-ray diffraction, energy dispersive X-ray and Auger spectroscopy, as well as optical and scanning electron microscopy. The wetting behavior of the test specimens is interpreted with respect to observed microstructural changes and as a function of aging time, solder composition, and processing conditions.

  16. Commentary: Photothermal effects of laser tissue soldering

    International Nuclear Information System (INIS)

    Menovsky, T.; Beek, J.F.; Gemert, M.J.C. van

    1999-01-01

    Full text: Laser tissue welding is the process of using laser energy to join tissues without sutures or with a reduced number of sutures. Recently, diode lasers have been added to the list of fusion lasers (Lewis and Uribe 1993, Reali et al 1993). Typically, for tissue welding, deep penetrating diode lasers emitting at 800-810 nm are used, in combination with a strong absorbing protein solder containing the dye indocyanine green. Indocyanine green has a maximum absorption coefficient at 805 nm and binds preferentially with proteins (Sauda et al 1986). The greatest advantage of diode lasers is their compact size, easy use and low cost. In this issue of Physics in Medicine and Biology (pp 983-1002, 'Photothermal effects of laser tissue soldering'), in an in vitro study, McNally et al investigate the optimal laser settings and welding temperatures in relation to the tensile strength and thermal damage of bovine aorta specimens. An interesting statement in their introduction is that the low strength of laser produced anastomoses can lead to aneurysm formation. The increased chance of aneurysm formation may merely be due to the thermal effect of the laser on the vascular wall, especially on the adventitia and media layers, which become necrotic after thermal injury. Subsequent haemodynamic stress exerted on a damaged vascular wall is a significant contributing factor for aneurysmal initiation. Also interesting is the remark that 'by the application of wavelength-specific chromophores in tissue welding ... the requirement for precise focusing and aiming of the laser beam may be removed'. Though perhaps not yet fully justified, this statement, if true, would facilitate surgical procedures. While the experiments are conducted in a proper manner, the use of bovine aorta specimens, which were stored at -70 deg. C and subsequently thawed for the tissue welding experiments, may not be the most appropriate for studying tissue effects or tensile strength measurements, as the

  17. Influence of ZnO nano-particles addition on thermal analysis, microstructure evolution and tensile behavior of Sn–5.0 wt% Sb–0.5 wt% Cu lead-free solder alloy

    Energy Technology Data Exchange (ETDEWEB)

    Fouda, A.N., E-mail: alynabieh@yahoo.com [Physics Department, Faculty of Science, Suez-Canal University, 41522 Ismailia (Egypt); Eid, E.A., E-mail: dr_eid_hti@yahoo.com [Basic Science Department, Higher Technological Institute, 44629 10th of Ramadan City (Egypt)

    2015-04-24

    Sn–5 wt%Sb–0.5 wt%Cu (plain SSC505) and Sn–5 wt%Sb–0.5 wt%Cu–0.5 wt% ZnO (SSC-ZnO) composite solder alloys have been studied. The variation in thermal behavior, microstructure and tensile characteristics associated with mixing of 0.5 wt% ZnO nano-metric particles to plain SSC505 solder were investigated. A slight increment in the melting temperature [ΔT{sub m}=0.89 °C] was recorded using differential scanning calorimetry (DSC) after addition of ZnO. X-Ray diffraction (XRD) analysis confirmed the existence of β-Sn, SbSn and Cu{sub 6}Sn{sub 5} intermetallic compounds (IMCs) beside some of ZnO planes in SSC-ZnO composite solder. Field emission scanning electronic microscope (FE-SEM) investigation of SSC-ZnO composite solder revealed a homogenous uniform distribution, size refinement of IMCs and β-Sn grains. Addition of ZnO nano-metric particles into the plain SSC505 enhanced the yield stress σ{sub YS} by ~12% and improved the ultimate tensile strength σ{sub UTS} by ~13%. In addition, adding ZnO nano-metric particles was found to be effective for reducing ductility by ~43% of the plain solder due to the refinement of β-Sn grains within SSC-ZnO composite solder. - Highlights: • Melting point of SSC505-ZnO composite solder is slightly increased by 0.89 {sup ο}C compared with the plain SSC505 solder. • XRD and EDX analysis reflect the presence of SbSn, Cu{sub 6}Sn{sub 5} IMCs. • EF-SEM images of SSC-ZnO composite solder revealed homogenous uniform distribution of β-Sn grains and fine IMC particles. • A detectable improvement in the Young modulus, ultimate tensile strength and yield strength were observed after addition of 0.5 wt% ZnO nano-metric particles.

  18. Formation of soft magnetic high entropy amorphous alloys composites containing in situ solid solution phase

    Science.gov (United States)

    Wei, Ran; Sun, Huan; Chen, Chen; Tao, Juan; Li, Fushan

    2018-03-01

    Fe-Co-Ni-Si-B high entropy amorphous alloys composites (HEAACs), which containing high entropy solid solution phase in amorphous matrix, show good soft magnetic properties and bending ductility even in optimal annealed state, were successfully developed by melt spinning method. The crystallization phase of the HEAACs is solid solution phase with body centered cubic (BCC) structure instead of brittle intermetallic phase. In addition, the BCC phase can transformed into face centered cubic (FCC) phase with temperature rise. Accordingly, Fe-Co-Ni-Si-B high entropy alloys (HEAs) with FCC structure and a small amount of BCC phase was prepared by copper mold casting method. The HEAs exhibit high yield strength (about 1200 MPa) and good plastic strain (about 18%). Meanwhile, soft magnetic characteristics of the HEAs are largely reserved from HEAACs. This work provides a new strategy to overcome the annealing induced brittleness of amorphous alloys and design new advanced materials with excellent comprehensive properties.

  19. Provenance and composition study on Terengganu inscribed stone using in-situ nuclear technology

    International Nuclear Information System (INIS)

    Jaafar Abdullah; Roslan Yahya; Hearie Hassan; Engku Mohd Fahmi Engku Chik; Mohamad Rabaie Shari; Airwan Affendi Mahmood; Abdul Quddoss Abu Bakar; Ainul Mardhiah Terry

    2012-01-01

    This paper focused on the analysis of trace elements and provenance study of the Inscribed Stone of Terengganu (BBPT) using Neutron-induced Prompt Gamma-Ray Techniques (NIPGAT). In this study, portable NIPGAT system was designed and developed by using volume-based measurement. It is a nondestructive testing technique for the samples. This system uses low activity of isotopic neutron radioactive source from californium-252 (Cf-252) as an irradiation source. Gamma ray spectroscopy as well as specialized computer software has been utilized to conduct the research. The study has determined that the stone was a dolerite stone based on the composition of the stone elements. Although most of the scientific data for this study have been collected, this project is still running to complete the scope of provenance study. (author)

  20. Fish-mediated changes in bacterioplankton community composition: an in situ mesocosm experiment

    Science.gov (United States)

    Luo, Congqiang; Yi, Chunlong; Ni, Leyi; Guo, Longgen

    2017-06-01

    We characterized variations in bacterioplankton community composition (BCC) in mesocosms subject to three different treatments. Two groups contained fish (group one: Cyprinus carpio; group two: Hypophthalmichthys molitrix); and group three, the untreated mesocosm, was the control. Samples were taken seven times over a 49-day period, and BCC was analyzed by PCR-denaturing gradient gel electrophoresis (DGGE) and real-time quantitative PCR (qPCR). Results revealed that introduction of C. carpio and H. molitrix had a remarkable impact on the composition of bacterioplankton communities, and the BCC was significantly different between each treatment. Sequencing of DGGE bands revealed that the bacterioplankton community in the different treatment groups was consistent at a taxonomic level, but differed in its abundance. H. molitrix promoted the richness of Alphaproteobacteria and Actinobacteria, while more bands affiliated to Cyanobacteria were detected inC. carpio mesocosms. The redundancy analysis (RDA) result demonstrated that the BCC was closely related to the bottom-up (total phosphorus, chlorophyll a, phytoplankton biomass) and top-down forces (biomass of copepods and cladocera) in C. carpio and control mesocosms, respectively. We found no evidence for top-down regulation of BCC by zooplankton in H. molitrix mesocosms, while grazing by protozoa (heterotrophic nanoflagellates, ciliates) became the major way to regulate BCC. Total bacterioplankton abundances were significantly higher in C. carpio mesocosms because of high nutrient concentration and suspended solids. Our study provided insights into the relationship between fish and bacterioplankton at species level, leading to a deep understanding of the function of the microbial loop and the aquatic ecosystem.

  1. Fish-mediated changes in bacterioplankton community composition: an in situ mesocosm experiment

    Science.gov (United States)

    Luo, Congqiang; Yi, Chunlong; Ni, Leyi; Guo, Longgen

    2018-03-01

    We characterized variations in bacterioplankton community composition (BCC) in mesocosms subject to three different treatments. Two groups contained fish (group one: Cyprinus carpio; group two: Hypophthalmichthys molitrix); and group three, the untreated mesocosm, was the control. Samples were taken seven times over a 49-d period, and BCC was analyzed by PCR-denaturing gradient gel electrophoresis (DGGE) and real-time quantitative PCR (qPCR). Results revealed that introduction of C. carpio and H. molitrix had a remarkable impact on the composition of bacterioplankton communities, and the BCC was significantly different between each treatment. Sequencing of DGGE bands revealed that the bacterioplankton community in the different treatment groups was consistent at a taxonomic level, but differed in its abundance. H. molitrix promoted the richness of Alphaproteobacteria and Actinobacteria, while more bands affiliated to Cyanobacteria were detected in C. carpio mesocosms. The redundancy analysis (RDA) result demonstrated that the BCC was closely related to the bottom-up (total phosphorus, chlorophyll a, phytoplankton biomass) and top-down forces (biomass of copepods and cladocera) in C. carpio and control mesocosms, respectively. We found no evidence for top-down regulation of BCC by zooplankton in H. molitrix mesocosms, while grazing by protozoa (heterotrophic nanoflagellates, ciliates) became the major way to regulate BCC. Total bacterioplankton abundances were significantly higher in C. carpio mesocosms because of high nutrient concentration and suspended solids. Our study provided insights into the relationship between fish and bacterioplankton at species level, leading to a deep understanding of the function of the microbial loop and the aquatic ecosystem.

  2. 30 CFR 77.1112 - Welding, cutting, or soldering with arc or flame; safeguards.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, or soldering with arc or... WORK AREAS OF UNDERGROUND COAL MINES Fire Protection § 77.1112 Welding, cutting, or soldering with arc or flame; safeguards. (a) When welding, cutting, or soldering with arc or flame near combustible...

  3. 30 CFR 75.1106 - Welding, cutting, or soldering with arc or flame underground.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, or soldering with arc or... Protection § 75.1106 Welding, cutting, or soldering with arc or flame underground. [Statutory Provisions] All welding, cutting, or soldering with arc or flame in all underground areas of a coal mine shall, whenever...

  4. 30 CFR 77.1916 - Welding, cutting, and soldering; fire protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, and soldering; fire... OF UNDERGROUND COAL MINES Slope and Shaft Sinking § 77.1916 Welding, cutting, and soldering; fire protection. (a) One portable fire extinguisher shall be provided where welding, cutting, or soldering with...

  5. A Corrosion Investigation of Solder Candidates for High-Temperature Applications

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Ambat, Rajan

    2009-01-01

    The step soldering approach is being employed in the Multi-Chip module (MCM) technology. High lead containing alloys is one of the solders currently being used in this approach. Au-Sn and Au-Ge based candidate alloys have been proposed as alternative solders for this application. In this work...

  6. In-situ Non-Invasive Imaging of Liquid-Immersed Thin Film Composite Membranes

    KAUST Repository

    Ogieglo, Wojciech

    2017-10-14

    We present a non-invasive method to directly image liquid-immersed thin film composite membranes. The approach allows accessing information not only on the lateral distribution of the coating thickness, including variations in its swelling and density, but also on the distribution of substrate porosity, roughness, accessibility of pores to liquid, and even the degree of pore intrusion related to the thin layer deposition process. The method can be particularly helpful in the fields of functional coatings or membranes to allow laterally-resolved studies under realistic application conditions thereby opening completely new research avenues. The approach is demonstrated in a study of two polymers of intrinsic microporosity, PIM-1 and PIM-6FDA-OH, coated on polyacrylonitrile support and immersed in water. Variations of the skin morphology using different coating methods (floating, spin-coating and dip-coating) are evaluated with the help of the presented method. Surfaces of at least tens of cm2 can be potentially analyzed.

  7. Kefir: composition and evaluation of in situ antagonistic activity against Staphylococcus aureus and Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Simone Weschenfelder

    Full Text Available ABSTRACT The aim of this study was to investigate whether produced kefir meets the identity and quality standards for fermented milks, to check the possibility of assigning a nutrition declaration, and to evaluate the antagonistic activity of the fermented milk against Staphylococcus aureus and Escherichia coli. Two different formulations of kefir (Kefir 1 and Kefir 2 were prepared to determine the percentage composition, minerals, pH, total lactic acid bacteria, and antagonistic activity against Staphylococcus aureus and Escherichia coli. The results of the physicochemical evaluation indicated a statistically significant difference between the formulations, except for the percentage of lipids, Ca, K, Mg and Na. The formulations met the parameters of identity and quality in the fermented milks under evaluation. Possible nutrition declarations for Kefir 1 are 'source of proteins' and 'reduced calorie', and for Kefir 2, 'high protein content' and 'high zinc content'. The fermented milks showed significant antagonistic activity against the tested microorganisms (> 24 h, with no activity seen after this period. Further studies involving kefir are suggested, exploring its potential as a probiotic food, and its inclusion in the diet of the population.

  8. ACE-SWICS In Situ Plasma Composition of Fragmented Comet 73P/Schwassmann-Wachmann 3

    Science.gov (United States)

    Gilbert, J. A.; Lepri, S. T.; Rubin, M.; Zurbuchen, T.

    2013-12-01

    The interiors of comets contain some of the most pristine material in the solar system. Comet 73P/Schwassmann-Wachmann 3, discovered in 1930 with a double nucleus, is a Jupiter-family comet with a 5.34-year period. This comet split into 5 fragments in 1995 and disintegrated into nearly 70 pieces in 2006. In May and June of 2006, recently ionized cometary particles originating from some of these fragments were collected with the ACE-SWICS sensor. Due to a combination of the close proximity of the fragments passing between ACE-SWICS and the Sun, and the instrument characteristics, unique measurements regarding the charge state composition and the elemental abundances of both cometary and heliospheric plasma were made during this time. The cometary material released from some of these fragments can be identified by the concentrations of water-group pick-up ions having a mass-per-charge of 16-18 amu/e. With a focus on Helium, Carbon, and water-group ions, we present an analysis of the cometary plasma. Charge state ratios of C+/O+ fall below 0.1 during detection of comet fragment plasma, and there is a clear increase in He+ during fragment crossings. The C/O ratio and He charge states are used to provide constraints on the activity of the cometary fragments and also the spatial distribution of the extended and ionized cometary tail.

  9. In situ polymerized wood polymer composite: effect of additives and nanoclay on the thermal, mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Devi, Rashmi R; Maji, Tarun K., E-mail: tkm@tezu.ernet.in [Department of Chemical Sciences, Tezpur University, Assam, (India)

    2013-11-01

    This study concerns the preparation and characterization of wood polymer nanocomposites based on impregnation of styrene acrylonitrile co-polymer-nanoclay intercalating system in presence of glycidyl methacrylate (GMA), a cross linking agent, and vinyl trichloro silane (VTCS) as additives into Simul (Bombex ceiba, L.), a soft wood. The effect of nanoclay and VTCS on the properties of the resultant wood polymer nanocomposites (WPNC) has been evaluated. FTIR spectroscopy shows the interaction among wood, polymers, GMA, nanoclay and VTCS. The penetration of polymer and nanoclay into the wood cell wall is supported by SEM study. The distribution of nanoclay in the SAN polymer matrix present within the wood cell wall has been evidenced by TEM study. TGA results show an improvement in the thermostability of the resultant composites. The inclusion of VTCS enhances the self extinguishing behaviour of the WPNC as revealed by limiting oxygen index (LOI) test. Due to treatment, the resultant WPNC exhibits an improvement in all the properties like water repellency, dimensional stability, hardness, flexural, tensile and thermal stability compared to untreated wood. (author)

  10. In-situ ductile metal/bulk metallic glass matrix composites formed by chemical partitioning

    Science.gov (United States)

    Kim, Choong Paul; Hays, Charles C.; Johnson, William L.

    2004-03-23

    A composite metal object comprises ductile crystalline metal particles in an amorphous metal matrix. An alloy is heated above its liquidus temperature. Upon cooling from the high temperature melt, the alloy chemically partitions, forming dendrites in the melt. Upon cooling the remaining liquid below the glass transition temperature it freezes to the amorphous state, producing a two-phase microstructure containing crystalline particles in an amorphous metal matrix. The ductile metal particles have a size in the range of from 0.1 to 15 micrometers and spacing in the range of from 0.1 to 20 micrometers. Preferably, the particle size is in the range of from 0.5 to 8 micrometers and spacing is in the range of from 1 to 10 micrometers. The volume proportion of particles is in the range of from 5 to 50% and preferably 15 to 35%. Differential cooling can produce oriented dendrites of ductile metal phase in an amorphous matrix. Examples are given in the Zr--Ti--Cu--Ni--Be alloy bulk glass forming system with added niobium.

  11. In situ polymerized wood polymer composite: effect of additives and nanoclay on the thermal, mechanical properties

    International Nuclear Information System (INIS)

    Devi, Rashmi R; Maji, Tarun K.

    2013-01-01

    This study concerns the preparation and characterization of wood polymer nanocomposites based on impregnation of styrene acrylonitrile co-polymer–nanoclay intercalating system in presence of glycidyl methacrylate (GMA), a cross linking agent, and vinyl trichloro silane (VTCS) as additives into Simul (Bombex ceiba, L.), a soft wood. The effect of nanoclay and VTCS on the properties of the resultant wood polymer nanocomposites (WPNC) has been evaluated. FTIR spectroscopy shows the interaction among wood, polymers, GMA, nanoclay and VTCS. The penetration of polymer and nanoclay into the wood cell wall is supported by SEM study. The distribution of nanoclay in the SAN polymer matrix present within the wood cell wall has been evidenced by TEM study. TGA results show an improvement in the thermostability of the resultant composites. The inclusion of VTCS enhances the self extinguishing behaviour of the WPNC as revealed by limiting oxygen index (LOI) test. Due to treatment, the resultant WPNC exhibits an improvement in all the properties like water repellency, dimensional stability, hardness, flexural, tensile and thermal stability compared to untreated wood. (author)

  12. An Overview of Surface Finishes and Their Role in Printed Circuit Board Solderability and Solder Joint Performance

    Energy Technology Data Exchange (ETDEWEB)

    Vianco, P.T.

    1998-10-15

    A overview has been presented on the topic of alternative surface finishes for package I/Os and circuit board features. Aspects of processability and solder joint reliability were described for the following coatings: baseline hot-dipped, plated, and plated-and-fused 100Sn and Sn-Pb coatings; Ni/Au; Pd, Ni/Pd, and Ni/Pd/Au finishes; and the recently marketed immersion Ag coatings. The Ni/Au coatings appear to provide the all-around best option in terms of solderability protection and wire bondability. Nickel/Pal ftishes offer a slightly reduced level of performance in these areas that is most likely due to variable Pd surface conditions. It is necessmy to minimize dissolved Au or Pd contents in the solder material to prevent solder joint embrittlement. Ancillary aspects that included thickness measurement techniques; the importance of finish compatibility with conformal coatings and conductive adhesives; and the need for alternative finishes for the processing of non-Pb bearing solders were discussed.

  13. Automation of experimental research of waveguide paths induction soldering

    Science.gov (United States)

    Tynchenko, V. S.; Petrenko, V. E.; Kukartsev, V. V.; Tynchenko, V. V.; Antamoshkin, O. A.

    2018-05-01

    The article presents an automated system of experimental studies of the waveguide paths induction soldering process. The system is a part of additional software for a complex of automated control of the technological process of induction soldering of thin-walled waveguide paths from aluminum alloys, expanding its capabilities. The structure of the software product, the general appearance of the controls and the potential application possibilities are presented. The utility of the developed application by approbation in a series of field experiments was considered and justified. The application of the experimental research system makes it possible to improve the process under consideration, providing the possibility of fine-tuning the control regulators, as well as keeping the statistics of the soldering process in a convenient form for analysis.

  14. Optimization of the soldering process by the DMAIC methodology

    Directory of Open Access Journals (Sweden)

    Michał Zasadzień

    2016-06-01

    Full Text Available The chapter presents the use of the DMAIC method for the analysis and improvement of the process of soldering pins in a plug connecting a bundle of wires to the board of a controller; a part of the steering system of a car. The main problem in the soldering process, that is an unsatisfactory share of bad soldered connections between the board and the plug and the instability of that number, was identified by means of a five-phase improvement process. Key points and main causes of the defect were pointed out, and process improvement measures were suggested. Due to the analysis conducted and the correct implementation of improvement measures the share of defective connections has been decreased twofold.

  15. Development of KMnO(4)-releasing composites for in situ chemical oxidation of TCE-contaminated groundwater.

    Science.gov (United States)

    Liang, S H; Chen, K F; Wu, C S; Lin, Y H; Kao, C M

    2014-05-01

    The objective of this study was to develop a controlled-oxidant-release technology combining in situ chemical oxidation (ISCO) and permeable reactive barrier (PRB) concepts to remediate trichloroethene (TCE)-contaminated groundwater. In this study, a potassium permanganate (KMnO4)-releasing composite (PRC) was designed for KMnO4 release. The components of this PRC included polycaprolactone (PCL), KMnO4, and starch with a weight ratio of 1.14:2:0.96. Approximately 64% (w/w) of the KMnO4 was released from the PRC after 76 days of operation in a batch system. The results indicate that the released KMnO4 could oxidize TCE effectively. The results from a column study show that the KMnO4 released from 200 g of PRC could effectively remediate 101 pore volumes (PV) of TCE-contaminated groundwater (initial TCE concentration = 0.5 mg/L) and achieve up to 95% TCE removal. The effectiveness of the PRC system was verified by the following characteristics of the effluents collected after the PRC columns (barrier): (1) decreased TCE concentrations, (2) increased ORP and pH values, and (3) increased MnO2 and KMnO4 concentrations. The results of environmental scanning electron microscope (ESEM) analysis show that the PCL and starch completely filled up the pore spaces of the PRC, creating a composite with low porosity. Secondary micro-scale capillary permeability causes the KMnO4 release, mainly through a reaction-diffusion mechanism. The PRC developed could be used as an ISCO-based passive barrier system for plume control, and it has the potential to become a cost-effective alternative for the remediation of chlorinated solvent-contaminated groundwater. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Microstructural effects on constitutive and fatigue fracture behavior of TinSilverCopper solder

    Science.gov (United States)

    Tucker, Jonathon P.

    As microelectronic package construction becomes more diverse and complex, the need for accurate, geometry-independent material constitutive and failure models increases. Evaluations of packages based on accelerated environmental tests (such as accelerated thermal cycling or power cycling) only provide package-dependent reliability information. In addition, extrapolations of such test data to life predictions under field conditions are often empirical. Besides geometry, accelerated environmental test data must account for microstructural factors such as alloy composition or isothermal aging condition, resulting in expensive experimental variation. In this work, displacement-controlled, creep, and fatigue lap shear tests are conducted on specially designed SnAgCu test specimens with microstructures representative to those found in commercial microelectronic packages. The data are used to develop constitutive and fatigue fracture material models capable of describing deformation and fracture behavior for the relevant temperature and strain rate ranges. Furthermore, insight is provided into the microstructural variation of solder joints and the subsequent effect on material behavior. These models are appropriate for application to packages of any geometrical construction. The first focus of the thesis is on Pb-mixed SnAgCu solder alloys. During the transition from Pb-containing solders to Pb-free solders, joints composed of a mixture of SnPb and SnAgCu often result from either mixed assemblies or rework. Three alloys of 1, 5 and 20 weight percent Pb were selected so as to represent reasonable ranges of Pb contamination expected from different 63Sn37Pb components mixed with Sn3.0Ag0.5Cu. Displacement-controlled (constant strain rate) and creep tests were performed at temperatures of 25°C, 75°C, and 125°C using a double lap shear test setup that ensures a nearly homogeneous state of plastic strain at the joint interface. Rate-dependent constitutive models for Pb

  17. Paloma: In-situ Measurement of The Elemental and Isotopic Composition of The Mars Atmosphere

    Science.gov (United States)

    Chassefiere, E.; Jambon, A.; Berthelier, J.-J.; Correia, J.-J.; Covinhes, J.; Goulpeau, G.; Leblanc, F.; Malique, Ch.; Sarda, P.; Schaetzel, P.; Sabroux, J.-C.; Ferry, C.; Richon, P.; Pineau, J.-F.; Desjean, M.-C.

    The PALOMA instrument, presently under study in the frame of the NASA/CNES Mars exploration program, is devoted to the accurate measurement of isotopic and el- emental ratios in Mars atmosphere. It consists of a mass spectrometer coupled with a gas preparation line for separation of reactive and noble gas species, and noble gas species (and reactive gases) from each other, by chemical and cryogenic trapping, and possibly permeation techniques. This instrument, ranked among the most important four types of measurement recommended by the US Committee on Planetary and Lu- nar Exploration (COMPLEX), will be proposed as a part of the payload of the 07 NASA smart landers. The general objectives of PALOMA are to provide instanta- neous and time-varying patterns of noble gas isotopic spectra, and stable isotopes. Such measurements will allow to improve our general understanding of volatile cy- cles on Mars, and to better decipher the history of the atmosphere and climate. Past escape processes, exchanges between solid planet and atmosphere, post-accretional addition of volatil-rich matter from comets, are expected to have imprinted specific isotopic signatures. Although these signatures are strongly interlocked, a compara- tive Earth-Mars approach may allow to discriminate between them, and therefore to reconstruct the history of Martian volatiles. The evolution of atmospheric mass and composition may have had a major impact on climate evolution, e.g. through massive escape of carbon dioxide and water. In addition, precise measurements of isotopes in the present Mars atmosphere are the most promising way on the short term to confirm that SNC meteorites are from Martian origin. PALOMA also includes a small separate device for measuring ambient natural radioactivity, which might provide information about the presence of a near subsurface permafrost, possible residual volcanic activity, vertical mixing rate in the boundary layer.

  18. Drinking Water Contamination Due To Lead-based Solder

    Science.gov (United States)

    Garcia, N.; Bartelt, E.; Cuff, K. E.

    2004-12-01

    The presence of lead in drinking water creates many health hazards. Exposure to lead-contaminated water can affect the brain, the central nervous system, blood cells, and kidneys, causing such problems as mental retardation, kidney disease, heart disease, stroke, and death. One way in which lead can contaminate our water supply is through the use of lead solder to join pipes. Lead solder was widely used in the past because of its ease of application as well as its low cost. Lead contamination in residential areas has previously been found to be a particularly serious problem in first-draw samples, of water that has sat stagnant in pipes overnight. To investigate the time-dependence of drinking water lead contamination, we analyzed samples taken hourly of water exposed to lead solder. While our preliminary data was insufficient to show more than a rough correlation between time of exposure and lead concentration over short periods (1-3 hours), we were able to confirm that overnight exposure of water to lead-based solder results in the presence high levels of lead. We also investigated other, external factors that previous research has indicated contribute to increased concentrations of lead. Our analysis of samples of lead-exposed water at various pH and temperatures suggests that these factors can be equally significant in terms of their contribution to elevated lead concentration levels. In particular, water that is slightly corrosive appears to severely impact the solubility of lead. As this type of water is common in much of the Northeast United States, the presence of lead-based solder in residential areas there is especially problematic. Although lead-based solder has been banned since the 1980s, it remains a serious concern, and a practical solution still requires further research.

  19. Microstructure characteristics and properties of in-situ formed TiC/Ni based alloy composite coating by laser cladding

    Science.gov (United States)

    Yang, Sen; Liu, Wenjin; Zhong, Minlin

    2003-03-01

    Different weight ratio of nickel based alloy, titanium and graphite powders were mixed and then laser cladded onto carbon steel substrate to produce a surface metal matrix composite layer. The experimental results showed that the coating was uniform, continuous and free of cracks. An excellent bonding between the coating and the carbon steel substrate was ensured by the strong metallurgical interface. The microstructures of the coating were mainly composed of γ-Ni dendrite, M23C6, a small amount of CrB, and dispersed TiC particles, and the in-situ generated TiCp/matrix interfaces were clean and free from deleterious surface reaction. The morphologies of TiC particles changed from the global, cluster to flower-like shape, the volume fraction of TiCp and the microhardness gradually increased from the bottom to the top of the coating layer, and the maximum microhardness of the coating was about HV0.2850, 3 times larger than that of steel substrate. The volume fraction of TiC particles increased with increasing of volume fraction of Ti and C too.

  20. Microstructure of a Ni Matrix Composite Coating Reinforced by In-situ TiC Particles Using Plasma Cladding

    Institute of Scientific and Technical Information of China (English)

    WUYu-ping; WANGZe-hua; LINPing-hua

    2004-01-01

    Plasma cladding process was used to prepare the TiC/Ni composite coating on the mild steel substrates. The TiC particles were synthesized in-situ. Microstructure and properties of the coating were investigated by optical microscopy, X-Ray diffraction, SEM, TEM and microhardness tester. The results show that the interface between the coating and the substrate is metallurgically bonded. The coating was uniform and almost defect-free when [Ti+C] varied from 10% to 20% after ball milling. The microstructure of the coating is mainly composed of γ-Ni dendrite, interdendritic eutectic (γ-Ni austenite, M23C6 and CrB) and TiC particles. Most of the TiC particles are spherical and a small fraction is blocky in size of 1-2μm. The TiC particles are smaller at the bottom than near the top of the coating. The coating has a gradient microstructure and a highest hardness of 1000Hv0.1.

  1. The wear properties of in-situ 7075 Al-Ti composites produced by powder metallurgy route

    Energy Technology Data Exchange (ETDEWEB)

    Ay, H.; Özyurek, D.; Yıldırım, M., E-mail: musayildirim@karabuk.edu.tr [Karabük University, Technology Faculty, Department of Manufacturing Engineering / Karabuk (Turkey); Bostan, B. [Gazi University, Technology Faculty, Department of Metallurgy and Materials Engineering (Turkey)

    2016-04-21

    In this study, the wear properties of in-situ 7075 Al-Ti composites produced by powder metallurgy route were investigated. Different amount of Ti (2, 4, 6 %) added to gas atomized 7075 Al alloy powders and they were mixed in turbula with 47rpm for 45 minutes. Then the mixed powders were pre-shaped by press under 600 MPa pressure. The samples were cooled in the furnace after sintered at 580 °C for 4 hours in the atmosphere controlled furnace. Standard metallographic process such as grinding, polishing and etching were applied to sintered samples. The hardness values were measured. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD) examines were carried out. The wear tests were performed in a pin-on disc type wear apparatus with 1 ms{sup −1} sliding speed at six different sliding distance (500-3000 m) under 30 N loads. As a result of studies, hardness values were increased with increasing Ti content, in addition the weight losses were decreased with increasing Ti amount.

  2. Manufacturing technology of integrated textile-based sensor networks for in situ monitoring applications of composite wind turbine blades

    Science.gov (United States)

    Haentzsche, Eric; Mueller, Ralf; Huebner, Matthias; Ruder, Tristan; Unger, Reimar; Nocke, Andreas; Cherif, Chokri

    2016-10-01

    Based on in situ strain sensors consisting of piezo-resistive carbon filament yarns (CFYs), which have been successfully integrated into textile reinforcement structures during their textile-technological manufacturing process, a continuous load of fibre-reinforced plastic (FRP) components has been realised. These sensors are also suitable for structural health monitoring (SHM) applications. The two-dimensional sensor layout is made feasible by the usage of a modular warp yarn path manipulation unit. Using a functional model of a small wind turbine blade in thermoset composite design, the sensor function for basic SHM applications (e.g. static load monitoring) are demonstrated. Any mechanical loads along the pressure or suction side of the wind turbine blade can be measured and calculated via a correlative change in resistance of the CFYs within the textile reinforcement plies. Performing quasi-static load tests on both tensile specimen and full-scale wind turbine blade, elementary results have been obtained concerning electro-mechanical behaviour and spatial resolution of global and even local static stresses according to the CFY sensor integration length. This paper demonstrates the great potential of textile-based and textile-technological integrated sensors in reinforcement structures for future SHM applications of FRPs.

  3. Micromechanical and in situ shear testing of Al–SiC nanolaminate composites in a transmission electron microscope (TEM)

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, C. [Materials Science and Engineering, Arizona State University, Tempe, AZ 85287-6106 (United States); Li, N.; Mara, N. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Albuquerque, NM (United States); Chawla, N., E-mail: nchawla@asu.edu [Materials Science and Engineering, Arizona State University, Tempe, AZ 85287-6106 (United States)

    2015-01-05

    Nanolaminate composites show promise as high strength and toughness materials. However, due to the limited volume of these materials, micron scale mechanical testing methods must be used to determine the properties of these films. To this end, a novel approach combining a double notch shear testing geometry and compression with a flat punch in a nanoindenter was developed to determine the mechanical properties of these films under shear loading. To further elucidate the failure mechanisms under shear loading, in situ TEM experiments were performed using a double notch geometry cut into the TEM foil. Aluminum layer thicknesses of 50 nm and 100 nm were used to show the effect of constraint on the deformation. Higher shear strength was observed in the 50 nm sample (690±54 MPa) compared to the 100 nm sample (423±28.7 MPa). Additionally, failure occurred close to the Al–SiC interface in the 50 nm sample as opposed to failure within the Al layer in the 100 nm sample.

  4. In Situ Strength Model for Continuous Fibers and Multi-Scale Modeling the Fracture of C/SiC Composites

    Science.gov (United States)

    Zhang, Sheng; Gao, Xiguang; Song, Yingdong

    2018-04-01

    A new in situ strength model of carbon fibers was developed based on the distribution of defects to predict the stress-strain response and the strength of C/SiC composites. Different levels of defects in the fibers were considered in this model. The defects in the fibers were classified by their effects on the strength of the fiber. The strength of each defect and the probability that the defect appears were obtained from the tensile test of single fibers. The strength model of carbon fibers was combined with the shear-lag model to predict the stress-strain responses and the strengths of fiber bundles and C/SiC minicomposites. To verify the strength model, tensile tests were performed on fiber bundles and C/SiC minicomposites. The predicted and experimental results were in good agreement. Effects of the fiber length, the fiber number and the heat treatment on the final strengths of fiber bundles and C/SiC minicomposites were also discussed.

  5. Fibrous hydroxyapatite–carbon nanotube composites by chemical vapor deposition: In situ fabrication, structural and morphological characterization

    International Nuclear Information System (INIS)

    Kosma, Vassiliki; Tsoufis, Theodoros; Koliou, Theodora; Kazantzis, Antonios; Beltsios, Konstantinos; De Hosson, Jeff Th. M.; Gournis, Dimitrios

    2013-01-01

    Highlights: ► CNTs synthesized on fibrous HA surfaces supporting Fe–Co bi- metallic catalysts by CVD. ► CNTs are rooted on HA distinct needle-like monocrystals and needle spherulitic aggregates. ► Reaction temperature and metal loading are critical parameters for CNT production. -- Abstract: Fibrous hydroxyapatite (HA)–carbon nanotube composites were synthesized by the catalytic decomposition of acetylene over Fe–Co bimetallic catalysts supported on the fibrous HA. Two forms of fibrous HA (distinct needle-like monocrystals and spherulitic aggregates of needles) were synthesized using a simple precipitation method and loaded with bimetallic catalysts (from 2 up to 20 wt%) by a wet chemical impregnation method. The HA supported catalysts were evaluated for the in situ growth of carbon nanotubes using the catalytic chemical vapor deposition method. The effect of reaction temperature and metal loading on the yield, structural perfection and morphology of the carbon products were investigated using a combination of X-ray diffraction, thermal analysis, Raman spectroscopy and scanning and transmission electron microscopies. The results revealed that both the selection of the growing conditions and the metal loading determine the yield and overall quality of the synthesized carbon nanotubes, which exhibit high graphitization degree when synthesized in high yields

  6. Fibrous hydroxyapatite–carbon nanotube composites by chemical vapor deposition: In situ fabrication, structural and morphological characterization

    Energy Technology Data Exchange (ETDEWEB)

    Kosma, Vassiliki; Tsoufis, Theodoros; Koliou, Theodora [Department of Materials Science and Engineering, University of Ioannina, GR-45110 Ioannina (Greece); Kazantzis, Antonios [Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747AG Groningen (Netherlands); Beltsios, Konstantinos [Department of Materials Science and Engineering, University of Ioannina, GR-45110 Ioannina (Greece); De Hosson, Jeff Th. M. [Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747AG Groningen (Netherlands); Gournis, Dimitrios, E-mail: dgourni@cc.uoi.gr [Department of Materials Science and Engineering, University of Ioannina, GR-45110 Ioannina (Greece)

    2013-04-20

    Highlights: ► CNTs synthesized on fibrous HA surfaces supporting Fe–Co bi- metallic catalysts by CVD. ► CNTs are rooted on HA distinct needle-like monocrystals and needle spherulitic aggregates. ► Reaction temperature and metal loading are critical parameters for CNT production. -- Abstract: Fibrous hydroxyapatite (HA)–carbon nanotube composites were synthesized by the catalytic decomposition of acetylene over Fe–Co bimetallic catalysts supported on the fibrous HA. Two forms of fibrous HA (distinct needle-like monocrystals and spherulitic aggregates of needles) were synthesized using a simple precipitation method and loaded with bimetallic catalysts (from 2 up to 20 wt%) by a wet chemical impregnation method. The HA supported catalysts were evaluated for the in situ growth of carbon nanotubes using the catalytic chemical vapor deposition method. The effect of reaction temperature and metal loading on the yield, structural perfection and morphology of the carbon products were investigated using a combination of X-ray diffraction, thermal analysis, Raman spectroscopy and scanning and transmission electron microscopies. The results revealed that both the selection of the growing conditions and the metal loading determine the yield and overall quality of the synthesized carbon nanotubes, which exhibit high graphitization degree when synthesized in high yields.

  7. In situ preparation of (TiB + TiC + Nd2O3)/Ti composites by powder metallurgy

    International Nuclear Information System (INIS)

    Lu Junqiang; Qin Jining; Lu Weijie; Liu Yang; Gu Jiajun; Zhang Di

    2009-01-01

    Titanium matrix composites reinforced with multiple ceramic particulates TiB, TiC and Nd 2 O 3 were prepared by powder metallurgy utilizing the chemical reactions among Ti, B 4 C, NdB 6 and oxygen in Ti powder. The thermodynamic feasibility of the in situ reaction has been calculated. The phases were identified by X-ray diffraction (XRD). The result shows that multiple ceramic phases TiB, TiC and Nd 2 O 3 particulates have been synthesized. The microstructures were examined by means of optical microscopy (OM), scanning electron microscopy (SEM), backscattered electron microscopy and transmission electron microscope (TEM). The results show that the reinforcements are distributed uniformly in the matrix alloy and grow in different shapes. TiB grows in needle shape; TiC and Nd 2 O 3 grow in equiaxed or near-equiaxed shapes. The addition of NdB 6 is beneficial to grain refinement, grain-boundary purification and porosity reduction

  8. Effect of directional solidification rate on the microstructure and properties of deformation-processed Cu–7Cr–0.1Ag in situ composites

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Keming [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China); School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Jiang, Zhengyi; Zhao, Jingwei [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522 (Australia); Zou, Jin; Chen, Zhibao [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China); Lu, Deping, E-mail: llludp@163.com [Jiangxi Key Laboratory for Advanced Copper and Tungsten Materials, Jiangxi Academy of Sciences, Nanchang 330029 (China)

    2014-11-05

    Highlights: • Effect of directional solidification (DS) rate on a Cu–Cr–Ag in situ composite. • The microstructure and properties of the DS in situ composite were investigated. • The second-phase Cr grains were parallel to drawing direction, and were finer. • The tensile strength was higher and the combination of properties was better. - Abstract: The influence of directional solidification rate on the microstructure, mechanical properties and conductivity of deformation-processed Cu–7Cr–0.1Ag in situ composites produced by thermo-mechanical processing was systematically investigated. The microstructure was analyzed by optical microscopy and scanning electronic microscopy. The mechanical properties and conductivity were evaluated by tensile-testing machine and micro-ohmmeter, respectively. The results indicate that the size, shape and distribution of second-phase Cr grains are significantly different in the Cu–7Cr–0.1Ag alloys with different growth rates. At a growth rate of 200 μm s{sup −1}, the Cr grains transform into fine Cr fiber-like grains parallel to the pulling direction from the Cr dendrites. The tensile strength of the Cu–7Cr–0.1Ag in situ composites from the directional solidification (DS) alloys is significantly higher than that from the as-cast alloy, while the conductivity of the in situ composites from the DS alloys is slightly lower than that from the as-cast alloy. The following combinations of tensile strength, elongation to fracture and conductivity of the Cu–7Cr–0.1Ag in situ composites from the DS alloy with a growth rate of 200 μm s{sup −1} and a cumulative cold deformation strain of 8 after isochronic aging treatment for 1 h can be obtained respectively as: (i) 1067 MPa, 2.9% and 74.9% IACS; or (ii) 1018 MPa, 3.0%, and 76.0% IACS or (iii) 906 MPa, 3.3% and 77.6% IACS.

  9. Microstructure and mechanical properties investigation of in situ TiB2 and ZrB2 reinforced Al-4Cu composites

    Science.gov (United States)

    Lutfi Anis, Ahmad; Ramli, Rosmamuhammadani; Darham, Widyani; Zakaria, Azlan; Talari, Mahesh Kumar

    2016-02-01

    Conventional Al-Cu alloys exhibit coarse grain structure leading to inferior mechanical properties in as-cast condition. Expensive thermo-mechanical treatments are needed to improve microstructure and corresponding mechanical properties. In situ Al-based composites were developed to improve mechanical properties by dispersion strengthening and grain refinement obtained by the presence of particulates in the melt during solidification. In this work Al-4Cu - 3TiB2 and Al-4Cu-3ZrB2 in situ composites were prepared by liquid casting method. XRD, electron microscopy and mechanical tests were performed on suitably sectioned and metallographically prepared surfaces to investigate the phase distribution, hardness and tensile properties. It was found that the reinforcement particles were segregated along the grain boundaries of Al dendrites. Tensile fracture morphology for both Al-4Cu - 3TiB2 and Al-4Cu-3ZrB2 were analyzed and compared to determine the fracture propagation mechanism in the composites. Al-4Cu-3ZrB2 in situ composites displayed higher strength and hardness compared to Al-4Cu-3TiB2 which could be ascribed to the stronger interfacial bonding between the Al dendrites and ZrB2 particulates as evidenced from fractographs.

  10. In-situ conversion of rGO/Ni2P composite from GO/Ni-MOF precursor with enhanced electrochemical property

    Science.gov (United States)

    Lv, Zijian; Zhong, Qin; Bu, Yunfei

    2018-05-01

    Owing to the metalloid characteristic and superior electrical conductivity, the metal phosphides have received increasing interests in energy storage systems. Here, xrGO/Ni2P composites are successfully synthesized via an In-situ phosphorization process with GO/Ni-MOF as precursors. Compared to pure Ni2P, the xrGO/Ni2P composites appear enhanced electrochemical properties in terms of the specific capacitance and cycling performance as electrodes for supercapacitors. Especially, the 2rGO/Ni2P electrode shows a highest specific capacitance of 890 F g-1 at 1 A g-1 among the obtained composites. The enhancement can be attributed to the inherited structure from Ni-MOF and the well assembled of rGO and Ni2P through the In-situ conversion process. Moreover, when applied as positive electrode in a hybrid supercapacitor, an energy density of 35.9 W h kg-1 at a power density of 752 W kg-1 has been achieved. This work provides an In-situ conversion strategy for the synthesis of rGO/Ni2P composite which might be a promising electrode material for SCs.

  11. Microstructure and Mechanical Properties of Multiphase Strengthened Al/Si/Al_2O_3/SiO_2/MWCNTs Nano composites Sintered by In Situ Vacuum Hot Pressing

    International Nuclear Information System (INIS)

    Li, J.; Jiang, X.; Zhu, D.; Zhu, M.; Shao, Z.; Johnson, S.; Luo, Z.

    2015-01-01

    Eutectic Al/Si binary alloy is technically one of the most important Al casting alloys due to its high corrosion resistance, evident shrinkage reduction, low thermal expansion coefficient, high fluidity, and good weldability. In this work, multi phased Al/Si matrix nano composites reinforced with Al_2O_3 and multi walled carbon nano tubes (MWCNTs) have been sintered by an in situ vacuum hot-pressing method. The alumina Al_2O_3 nanoparticles were introduced by an in situ reaction of Al with SiO_2. Microstructure and mechanical properties of the sintered Al/Si/Al_2O_3/SiO_2/MWCNTs nano composites with different alumina contents were investigated. The mechanical properties were determined by micro-Vickers hardness and compressive and shear strength tests. The results demonstrated that in situ alumina and MWCNTs had impacts on microstructure and mechanical properties of the nano composites. Based on the mechanical properties and microstructure of the nano composites, strengthening and fracture mechanisms by multiple reinforcements were analyzed

  12. In situ fabrication of nickel aluminum-layered double hydroxide nanosheets/hollow carbon nanofibers composite as a novel electrode material for supercapacitors

    Science.gov (United States)

    He, Fang; Hu, Zhibiao; Liu, Kaiyu; Zhang, Shuirong; Liu, Hongtao; Sang, Shangbin

    2014-12-01

    This paper introduces a new design route to fabricate nickel aluminum-layered double hydroxide (NiAl-LDH) nanosheets/hollow carbon nanofibers (CNFs) composite through an in situ growth method. The NiAl-LDH thin layers which grow on hollow carbon nanofibers have an average thickness of 13.6 nm. The galvanostatic charge-discharge test of the NiAl-LDH/CNFs composite yields an impressive specific capacitance of 1613 F g-1 at 1 A g-1 in 6 M KOH solution, the composite shows a remarkable specific capacitance of 1110 F g-1 even at a high current density of 10 A g-1. Furthermore, the composite remains a specific capacitance of 1406 F g-1 after 1000 cycles at 2 A g-1, indicating the composite has excellent high-current capacitive behavior and good cycle stability in compared to pristine NiAl-LDH.

  13. Thermomechanical behavior of tin-rich (lead-free) solders

    Science.gov (United States)

    Sidhu, Rajen Singh

    In order to adequately characterize the behavior of ball-grid-array (BGA) Pb-free solder spheres in electronic devices, the microstructure and thermomechanical behavior need to be studied. Microstructure characterization of pure Sn, Sn-0.7Cu, Sn-3.5Ag, and Sn-3.9Ag-0.7Cu alloys was conducted using optical microscopy, scanning electron microscopy, transmission electron microscopy, image analysis, and a novel serial sectioning 3D reconstruction process. Microstructure-based finite-element method (FEM) modeling of deformation in Sn-3.5Ag alloy was conducted, and it will be shown that this technique is more accurate when compared to traditional unit cell models for simulating and understanding material behavior. The effect of cooling rate on microstructure and creep behavior of bulk Sn-rich solders was studied. The creep behavior was evaluated at 25, 95, and 120°C. Faster cooling rates were found to increase the creep strength of the solders due to refinement of the solder microstructure. The creep behavior of Sn-rich single solder spheres reflowed on Cu substrates was studied at 25, 60, 95, and 130°C. Testing was conducted using a microforce testing system, with lap-shear geometry samples. The solder joints displayed two distinct creep behaviors: (a) precipitation-strengthening (Sn-3.5Ag and Sn-3.9Ag-0.7Cu) and (b) power law creep accommodated by grain boundary sliding (GBS) (Sn and Sn-0.7Cu). The relationship between microstructural features (i.e. intermetallic particle size and spacing), stress exponents, threshold stress, and activation energies are discussed. The relationship between small-length scale creep behavior and bulk behavior is also addressed. To better understand the damage evolution in Sn-rich solder joints during thermal fatigue, the local damage will be correlated to the cyclic hysteresis behavior and crystal orientations present in the Sn phase of solder joints. FEM modeling will also be utilized to better understand the macroscopic and local

  14. Curiosity and the Four Seasons: In Situ Measurements of the Atmospheric Composition over Three Mars Years

    Science.gov (United States)

    Trainer, M. G.; Franz, H. B.; Mahaffy, P. R.; Malespin, C.; Wong, M. H.; Atreya, S. K.; Becker, R. H.; Conrad, P. G.; Lefèvre, F.; Manning, H. L. K.; Martin-Torres, F. J.; McConnochie, T.; McKay, C.; Navarro-Gonzalez, R.; Pepin, R. O.; Webster, C. R.; Zorzano, M. P.

    2017-12-01

    The Sample Analysis at Mars (SAM) instrument onboard the Mars Science Laboratory Curiosity rover measures the chemical composition of major atmospheric species in the vicinity of the rover through a dedicated atmospheric inlet. We report here on measurements of atmospheric volume mixing ratios in Gale Crater using the SAM quadrupole mass spectrometer (QMS), over a period of nearly three Mars years (5 Earth years) from landing. The observation period spans the southern winter of MY 31, solar longitude (Ls) of 175° through southern fall of MY 34, Ls = 12°. The initial mixing ratios measured by the SAM QMS were reported for the first 105 sols of the mission [1], and were updated to account for newly developed calibration factors [2]. The SAM QMS atmospheric measurements were continued, periodically interspersed between solid sample measurements and other rover activities, with a cumulative coverage of 4 or 5 experiments per season. The three major volatiles - CO2, N2, and 40Ar - are compatible with the annual pressure cycle but with a repeatable lag that indicates incomplete mixing and the influences of seasonal circulation patterns. The mixing ratios for the two inert, non-condensable species are qualitatively consistent with what is predicted from annual cycle of CO2 deposition and sublimation at the poles, which is manifested in a large enhancement of Ar mixing ratio at the winter poles (and assumed for N2) [3]. The mixing ratio for the minor species O2 appears to follow a distinct seasonal trend and may be indicative of possible deviations from known atmospheric chemistry or a surface flux of oxygen from an unknown source, or both. This unprecedented seasonal coverage and precision in mixing ratio determination provides valuable data for understanding the seasonal chemical and dynamics cycles. Further, this measurement campaign supplies useful ground-truth data for global climate model simulations, which can study atmospheric effects for other locations on Mars

  15. Facile in situ solvothermal method to synthesize MWCNT/SnIn4S8 composites with enhanced visible light photocatalytic activity

    International Nuclear Information System (INIS)

    Ding, Chaoying; Tian, Li; Liu, Bo; Liang, Qian; Li, Zhongyu; Xu, Song; Liu, Qiaoli; Lu, Dayong

    2015-01-01

    Highlights: • MWCNT/SnIn 4 S 8 composites were facilely fabricated via in situ solvothermal method. • MWCNT/SnIn 4 S 8 composites exhibited significantly enhanced visible-light activity. • MWCNT/SnIn 4 S 8 composites showed remarkable visible light photocatalytic activity. • MWCNT/SnIn 4 S 8 composites exhibited excellent photo-stability. • Possible photocatalytic mechanism under visible-light irradiation was proposed. - Abstract: Superior photocatalytic activity could be achieved by multi-walled carbon nanotube (MWCNT) incorporated in the porous assembly of marigold-like SnIn 4 S 8 heterostructures synthesized by a flexible in-situ solvothermal method. The as-prepared MWCNT/SnIn 4 S 8 composites were well-characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic properties of the as-prepared samples were tested by photo-degradation of aqueous malachite green (MG) under the irradiation of visible light. It was found that the MWCNT/SnIn 4 S 8 composites showed enhanced visible light photocatalytic activity for dye degradation, and an optimum photocatalytic activity was observed over 3.0 wt.% MWCNT incorporated SnIn 4 S 8 composites. The superior photocatalytic activity of MWCNT/SnIn 4 S 8 composites could be ascribed to the existence of MWCNT which could serve as a good electron acceptor, mediator as well as the co-catalyst for dye degradation. The synergistic effect between SnIn 4 S 8 and MWCNT in the composites facilitated the interfacial charge transfer driven by the excitation of SnIn 4 S 8 under visible-light irradiation. Furthermore, a possible mechanism for the photocatalytic degradation of MWCNT/SnIn 4 S 8 composites was also discussed

  16. Effect of friction stir welding on microstructure, mechanical and wear properties of AA6061/ZrB2 in situ cast composites

    International Nuclear Information System (INIS)

    Dinaharan, I.; Murugan, N.

    2012-01-01

    Highlights: ► Application of FSW to join AA6061/ZrB 2 in situ composites. ► Homogenous distribution of ZrB 2 particles in the weld zone. ► Clusters in the parent composite are fragmented by the stirring action of the tool. ► Hardening of weld zone. ► FSW enhanced the wear resistance of the composite. - Abstract: Inadequate development of fabrication methods restricts the applications of new families of aluminum matrix composites (AMCs). Friction stir welding (FSW) is a potential candidate to join AMCs without any defects associated with conventional fusion welding processes. The primary objective of the present work is to apply FSW process to join AA6061/(0, 5 and 10 wt.%) ZrB 2 in situ cast composites and evaluate the joint properties. The composites were prepared by reacting inorganic salts K 2 ZrF 6 and KBF 4 with molten aluminum and joined using a FSW machine at a tool rotational speed of 1150 rpm, welding speed of 50 mm/min and axial force of 6 kN. The joints showed the presence of various zones such as weld zone (WZ), thermomechanically affected zone (TMAZ) and heat affected zone (HAZ). The weld zone was characterized with a homogenous distribution of ZrB 2 particles. The stirring action of the tool resulted in fragmentation of several clusters present in the parent composite. The weld zone exhibited higher hardness than that of the parent composite. The tensile strength of welded joints was comparable to that of parent composites. The wear resistance of the composites improved subsequent to FSW.

  17. New Textile Sensors for In Situ Structural Health Monitoring of Textile Reinforced Thermoplastic Composites Based on the Conductive Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) Polymer Complex.

    Science.gov (United States)

    Jerkovic, Ivona; Koncar, Vladan; Grancaric, Ana Marija

    2017-10-10

    Many metallic structural and non-structural parts used in the transportation industry can be replaced by textile-reinforced composites. Composites made from a polymeric matrix and fibrous reinforcement have been increasingly studied during the last decade. On the other hand, the fast development of smart textile structures seems to be a very promising solution for in situ structural health monitoring of composite parts. In order to optimize composites' quality and their lifetime all the production steps have to be monitored in real time. Textile sensors embedded in the composite reinforcement and having the same mechanical properties as the yarns used to make the reinforcement exhibit actuating and sensing capabilities. This paper presents a new generation of textile fibrous sensors based on the conductive polymer complex poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) developed by an original roll to roll coating method. Conductive coating for yarn treatment was defined according to the preliminary study of percolation threshold of this polymer complex. The percolation threshold determination was based on conductive dry films' electrical properties analysis, in order to develop highly sensitive sensors. A novel laboratory equipment was designed and produced for yarn coating to ensure effective and equally distributed coating of electroconductive polymer without distortion of textile properties. The electromechanical properties of the textile fibrous sensors confirmed their suitability for in situ structural damages detection of textile reinforced thermoplastic composites in real time.

  18. Manufacture of nano graphite oxides derived from aqueous glucose solutions and in-situ synthesis of magnetite–graphite oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiang, E-mail: liuxiang@ahut.edu.cn; Zhao, Tiantian; Liu, Pengpeng; Cui, Ping, E-mail: cokecp@sohu.com; Hu, Peng

    2015-03-01

    A “bottom up” approach of manufacturing graphite oxides (GOs) derived from aqueous glucose solutions by virtue of an environmentally-friendly process and the way of in-situ synthesizing magnetite–GOs composites are described in this work in detail. The dehydrations among glucose molecules under hydrothermal condition result in the initial carbon quantum dots and ultimate GOs. The structural information of the GOs is obtained by the infrared, ultraviolet–visible and X-ray photoelectron spectra. The magnetite–GOs composites were obtained by a one-pot method under the same hydrothermal conditions as the one of preparing GOs. The composites perform high activities in catalytic degradation of Rhodamine B in the presence of hydrogen peroxides without extra heating or pH adjusting. Both the GOs and the magnetite–GOs composites are also assured by measurements of transmission electron microscope and X-ray powder diffraction. - Highlights: • Graphite oxides are made from aqueous glucose solutions by hydrothermal reaction. • A way of in-situ synthesizing composites of magnetite–graphite oxides is depicted. • The composites perform high activities in catalytic degradation of Rhodamine B.

  19. In situ hydrothermal synthesis of a novel hierarchically porous TS-1/modified-diatomite composite for methylene blue (MB) removal by the synergistic effect of adsorption and photocatalysis.

    Science.gov (United States)

    Yuan, Weiwei; Yuan, Peng; Liu, Dong; Yu, Wenbin; Laipan, Minwang; Deng, Liangliang; Chen, Fanrong

    2016-01-15

    Hierarchically porous TS-1/modified-diatomite composites with high removal efficiency for methylene blue (MB) were prepared via a facile in situ hydrothermal route. The surface charge state of the diatomite was modified to enhance the electrostatic interactions, followed by in situ hydrothermal coating with TS-1 nanoparticles. The zeolite loading amount in the composites could be adjusted by changing the hydrothermal time. The highest specific surface area and micropore volume of the obtained composites were 521.3m(2)/g and 0.254cm(3)/g, respectively, with an optimized zeolite loading amount of 96.8%. Based on the synergistic effect of efficient adsorption and photocatalysis resulting from the newly formed hierarchically porous structure and improved dispersion of TS-1 nanoparticles onto diatomite, the composites' removal efficiency for MB reached 99.1% after 2h of photocatalytic reaction, even higher than that observed using pure TS-1 nanoparticles. Moreover, the superior MB removal kinetics of the composites were well represented by a pseudo-first-order model, with a rate constant (5.28×10(-2)min(-1)) more than twice as high as that of pure TS-1 nanoparticles (2.43×10(-2)min(-1)). The significant dye removal performance of this novel TS-1/modified-diatomite composite indicates that it is a promising candidate for use in waste water treatment. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Influence of solder joint length to the mechanical aspect during the thermal stress analysis

    Science.gov (United States)

    Tan, J. S.; Khor, C. Y.; Rahim, Wan Mohd Faizal Wan Abd; Ishak, Muhammad Ikman; Rosli, M. U.; Jamalludin, Mohd Riduan; Zakaria, M. S.; Nawi, M. A. M.; Aziz, M. S. Abdul; Ani, F. Che

    2017-09-01

    Solder joint is an important interconnector in surface mount technology (SMT) assembly process. The real time stress, strain and displacement of the solder joint is difficult to observe and assess the experiment. To tackle these problems, simulation analysis was employed to study the von Mises stress, strain and displacement in the thermal stress analysis by using Finite element based software. In this study, a model of leadless electronic package was considered. The thermal stress analysis was performed to investigate the effect of the solder length to those mechanical aspects. The simulation results revealed that solder length gives significant effect to the maximum von Mises stress to the solder joint. Besides, changes in solder length also influence the displacement of the solder joint in the thermal environment. The increment of the solder length significantly reduces the von Mises stress and strain on the solder joint. Thus, the understanding of the physical parameter for solder joint is important for engineer prior to designing the solder joint of the electronic component.

  1. High-Temperature Lead-Free Solder Alternatives: Possibilities and Properties

    DEFF Research Database (Denmark)

    High-temperature solders have been widely used as joining materials to provide stable interconnections that resist a severe thermal environment and also to facilitate the drive for miniaturization. High-lead containing solders have been commonly used as high-temperature solders. The development...... of high-temperature lead-free solders has become an important issue for both the electronics and automobile industries because of the health and environmental concerns associated with lead usage. Unfortunately, limited choices are available as high-temperature lead-free solders. This work outlines...... the criteria for the evaluation of a new high-temperature lead-free solder material. A list of potential ternary high-temperature lead-free solder alternatives based on the Au-Sn and Au-Ge systems is proposed. Furthermore, a comprehensive comparison of the high-temperature stability of microstructures...

  2. Reliability of lead-free solder joints with different PCB surface finishes under thermal cycling

    Energy Technology Data Exchange (ETDEWEB)

    Xia Yanghua [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)], E-mail: xia_yanghua@hotmail.com; Xie Xiaoming [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

    2008-04-24

    The reliability of lead-free electronic assemblies under thermal cycling was investigated. Thin small outline package (TSOP) devices with FeNi leads were reflow soldered on FR4 PCB (printed circuit board) with Sn3.0Ag0.5Cu (wt%) solder. The effects of different PCB finishes (organic solderability preservative (OSP) and electroless nickel immersion gold (ENIG)) were studied. The results show that OSP finish reveals better performance than its ENIG counterparts. The crack originates at the fringe of heel fillet in both cases. The propagation of crack in the ENIG case is along the device/solder interface, while in the case of OSP, the crack extends parallel to the solder/PCB interface. When the OSP finishes are employed, many Cu6Sn5 precipitates form inside the bulk solder and have a strengthening effect on the solder joint, resulting in better reliability performance as compared to those with ENIG finishes.

  3. Soldering and brazing safety guide: A handbook on space practice for those involved in soldering and brazing

    Science.gov (United States)

    This manual provides those involved in welding and brazing with effective safety procedures for use in performance of their jobs. Hazards exist in four types of general soldering and brazing processes: (1) cleaning; (2) application of flux; (3) application of heat and filler metal; and (4) residue cleaning. Most hazards during those operations can be avoided by using care, proper ventilation, protective clothing and equipment. Specific process hazards for various methods of brazing and soldering are treated. Methods to check ventilation are presented as well as a check of personal hygiene and good maintenance practices are stressed. Several emergency first aid treatments are described.

  4. ECAP consolidation of Al matrix composites reinforced with in-situ γ-Al{sub 2}O{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Casati, R., E-mail: riccardo.casati@polimi.it [Department of Mechanical Engineering, Politecnico di Milano, Via La Masa 1, Milano (Italy); Fabrizi, A. [Department of Management and Engineering, Università di Padova, Stradella S. Nicola 3, Vicenza (Italy); Tuissi, A. [CNR-IENI, Corso Promessi Sposi 29, Lecco (Italy); Xia, K. [Department of Mechanical Engineering, University of Melbourne, Victoria 3010 (Australia); Vedani, M. [Department of Mechanical Engineering, Politecnico di Milano, Via La Masa 1, Milano (Italy)

    2015-11-11

    This work is aimed at proposing a method to prepare aluminum matrix composites reinforced with γ-Al{sub 2}O{sub 3} nanoparticles and at describing the effects of an in-situ reaction on the resulting nano-reinforcement dispersed throughout the metal matrix. Al nano- and micro-particles were used as starting materials. They were consolidated by equal channel angular pressing (ECAP) in as-received conditions and after undergoing high-energy ball milling. Further, γ-Al{sub 2}O{sub 3} reinforcing nanoparticles were produced in-situ from the hydroxide layer that covered the Al powder particles. The powder particle morphology and the composites microstructures were investigated by electron microscopy. The transformation process was monitored by X-ray diffraction, differential scanning calorimetry and thermo-gravimetric analysis.

  5. Influence of in situ synthesized TiC on thermal stability and corrosion behavior of Zr60Cu10Al15Ni15 amorphous composites

    International Nuclear Information System (INIS)

    Geng, Jiwei; Teng, Xinying; Zhou, Guorong; Leng, Jinfeng; Zhao, Degang

    2014-01-01

    In situ synthesized TiC particles were prepared by a thermal explosion method. Adding “in situ synthesized” TiC into Zr 60 Cu 10 Al 15 Ni 15 glass matrix to obtain amorphous matrix composites was achieved. The corrosion behavior of Zr 60 Cu 10 Al 15 Ni 15 amorphous composites was evaluated using potentiodynamic polarization measurements in 3.5 wt% NaCl solution at room temperature. The results show that the microhardness and thermal stability are improved apparently, while the TiC (≤0.6 wt%) does not significantly affect the supercooled liquid behavior. Moreover, the corrosion resistance is improved apparently because the nanocrystals accelerate the diffusion of passive elements for faster formation of the protective passive film at nanocrystals/amorphous interfaces. However, when the TiC content is more than 0.6 wt%, both glass forming ability and corrosion resistance are reduced significantly

  6. Development of high-speed reactive processing system for carbon fiber-reinforced polyamide-6 composite: In-situ anionic ring-opening polymerization

    International Nuclear Information System (INIS)

    Kim, Sang-Woo; Seong, Dong Gi; Yi, Jin-Woo; Um, Moon-Kwang

    2016-01-01

    In order to manufacture carbon fiber-reinforced polyamide-6 (PA-6) composite, we optimized the reactive processing system. The in-situ anionic ring-opening polymerization of ε-caprolactam was utilized with proper catalyst and initiator for PA-6 matrix. The mechanical properties such as tensile strength, inter-laminar shear strength and compressive strength of the produced carbon fiber-reinforced PA-6 composite were measured, which were compared with the corresponding scanning electron microscope (SEM) images to investigate the polymer properties as well as the interfacial interaction between fiber and polymer matrix. Furthermore, kinetics of in-situ anionic ring-opening polymerization of ε-caprolactam will be discussed in the viewpoint of increasing manufacturing speed and interfacial bonding between PA-6 matrix and carbon fiber during polymerization.

  7. Development of high-speed reactive processing system for carbon fiber-reinforced polyamide-6 composite: In-situ anionic ring-opening polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang-Woo; Seong, Dong Gi; Yi, Jin-Woo; Um, Moon-Kwang [Composites Research Division, Korea Institute of Materials Science (KIMS), Changwon, Gyeongnam, 642–831 (Korea, Republic of)

    2016-05-18

    In order to manufacture carbon fiber-reinforced polyamide-6 (PA-6) composite, we optimized the reactive processing system. The in-situ anionic ring-opening polymerization of ε-caprolactam was utilized with proper catalyst and initiator for PA-6 matrix. The mechanical properties such as tensile strength, inter-laminar shear strength and compressive strength of the produced carbon fiber-reinforced PA-6 composite were measured, which were compared with the corresponding scanning electron microscope (SEM) images to investigate the polymer properties as well as the interfacial interaction between fiber and polymer matrix. Furthermore, kinetics of in-situ anionic ring-opening polymerization of ε-caprolactam will be discussed in the viewpoint of increasing manufacturing speed and interfacial bonding between PA-6 matrix and carbon fiber during polymerization.

  8. Interactions of Cu-substrates with titanium-alloyed Sn-Zn solders

    Directory of Open Access Journals (Sweden)

    Soares D.

    2006-01-01

    Full Text Available The interactions of copper substrate with titanium-alloyed Sn-Zn eutectic solders have been studied. Two series of experiments have been performed. The first one consisted in differential thermal analyses of Sn-Zn nearly eutectic alloys containing from 1.3 to 2.2 wt. % Ti. Diffusion couples consisted of Cu-wires and Sn-Zn-Ti liquid solders, produced at 250 and 275 OC have been prepared in the second series,. The contact times were up to 3600 s. The contact zones have been characterized by optical and scanning electron microscope. Two layers have been found along the interfaces solid/liquid. The first and the second layers are identical, respectively, with γ and ε phases of the Cu-Zn system. No changes of the chemical compositions were detected for the tested temperatures and reaction times. Continuous parabolic growth of the total diffusion zone thickness with the time of diffusion is observed. The growth is due mainly to one the formed layers (γ while the thickness of the ε-phase layer, stays almost constant for all tested diffusion times and temperatures.

  9. Behavior of Sn-0.7Cu-xZn lead free solder on physical properties and micro structure

    Science.gov (United States)

    Siahaan, Erwin

    2017-09-01

    The issues to substitute Tin-Lead Solders is concerning the health and environmental hazards that is caused by lead, and also legislative actions around the world regarding lead toxicity, which has prompted the research community to attempt to replace solder alloys for the traditional Sn-Pb alloys lead which has been used by industrial worker throughout history because it is easily extracted and refined at a relatively low energy cost and also has a range of useful properties. Traditional industry lead has been used in soldering materials for electronic applications because it has low melting point and a soft, malleable nature, when combined with tin at the eutectic composition which causes the alloy to flow easily in the liquid state and solidifies over a very small range of temperature. One of the potential candidate to replace tin-lead solder is Sn-Cu-Zn eutectic alloy as it has a lower melting temperature. Consequently, it is of interest to determine what reactions can occur in ternary systems derived from the Sn-Cu-Zn eutectic. One such system is Sn-0.7Cu-xZn. The specimen was elaborated on physical properties. The chemical content was analyzed by using Shimadzu XRD and melting point was analyzed by using Differential Scanning Calorimeter ( DSC ). The results has shown that the highest addition of Zinc content (15%Zn) will decrease the melting temperatur to 189°C compared to Sn-Pb at 183°C Increasing the amount of Zn on Sn0.7Cu-xZn alloys will decrease Cu3Sn intermetallic coumpound.

  10. A miniaturized laser-ablation mass spectrometer for in-situ measurements of isotope composition on solar body surfaces

    Science.gov (United States)

    Riedo, A.; Meyer, S.; Tulej, M.; Neuland, M.; Bieler, A.; Iakovleva, M.; Wurz, P.

    2012-04-01

    space instrument would have a cylindrical shape with a length of 120 mm, and a diameter of 60 mm, and a weight of about 1.5 kg (all electronics included). The mass analyzer supports high dynamic range of about 107 and a typical mass resolution of m/Δm~700. A computer-controlled optimizer controls the reproducibility of the performance of the mass analyzer, the laser fluence and the positioning of the sample. The system supports highly sensitive studies of elemental composition with sub-ppm detection limits. Our studies show that high accuracy and precision measurements can also be achieved in the investigations of isotopic patterns. Our initial studies of lead isotopic pattern indicated an accuracy and precision in the per mile range, which are comparable to that achieved by other - well known in isotopic analysis - mass spectrometric techniques, i.e., TIMS, SIMS, LA-ICP-MS used in the laboratory. The initial studies were conducted with Galena minerals and NIST standards. Hence, the miniaturized laser ablation time-of-flight mass spectrometer is a powerful instrument for in-situ measurements for the further investigation in surface characterization.

  11. Utilization of poly(methyl methacrylate) – carbon nanotube and polystyrene – carbon nanotube in situ polymerized composites as masterbatches for melt mixing

    OpenAIRE

    M. Lahelin; M. Annala; J. Seppala

    2012-01-01

    Carbon nanotubes (CNTs) were melt mixed directly or by using an in situ polymerized masterbatch into a matrix polymer, polystyrene (PS) or poly(methyl methacrylate) (PMMA). The mechanical properties of the composites were mostly determined by the amount of CNTs, and not by the use of directly melt mixed CNTs or the use of the masterbatch. In contrast, the electrical resistivity of the composites was dependent on the manner in which the CNTs were added to the matrix polymer. When there was inc...

  12. Horizon shells and BMS-like soldering transformations

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Matthias [Albert Einstein Center for Fundamental Physics,Institute for Theoretical Physics, University of Bern,Sidlerstrasse 5, 3012 Bern (Switzerland); O’Loughlin, Martin [University of Nova Gorica,Vipavska 13, 5000 Nova Gorica (Slovenia)

    2016-03-07

    We revisit the theory of null shells in general relativity, with a particular emphasis on null shells placed at horizons of black holes. We study in detail the considerable freedom that is available in the case that one solders two metrics together across null hypersurfaces (such as Killing horizons) for which the induced metric is invariant under translations along the null generators. In this case the group of soldering transformations turns out to be infinite dimensional, and these solderings create non-trivial horizon shells containing both massless matter and impulsive gravitational wave components. We also rephrase this result in the language of Carrollian symmetry groups. To illustrate this phenomenon we discuss in detail the example of shells on the horizon of the Schwarzschild black hole (with equal interior and exterior mass), uncovering a rich classical structure at the horizon and deriving an explicit expression for the general horizon shell energy-momentum tensor. In the special case of BMS-like soldering supertranslations we find a conserved shell-energy that is strikingly similar to the standard expression for asymptotic BMS supertranslation charges, suggesting a direct relation between the physical properties of these horizon shells and the recently proposed BMS supertranslation hair of a black hole.

  13. Thermomechanical fatigue of Sn-37 wt.% Pb model solder joints

    International Nuclear Information System (INIS)

    Liu, X.W.; Plumbridge, W.J.

    2003-01-01

    The fatigue of Sn-37 wt.% Pb model solder joints has been investigated under thermomechanical and thermal cycling. Based upon an analysis of displacements during thermomechancial cycling, a model solder joint has been designed to simulate actual joints in electronic packages. The strain-stress relationship, characterised by hysteresis loops, was determined during cycling from 30 to 125 deg. C, and the stress-range monitored throughout. The number of cycles to failure, as defined by the fall in stress range, was correlated to strain range and strain energy. The strain hardening exponent, k, varied with the definition of failure and, when a stress-range drop of 50% was used, it was 0.46. Cracks were produced during pure thermal cycling without external strains applied. These arose due to the local strains caused by thermal expansion mismatches between the solder and Cu 6 Sn 5 intermetallic layer, between the phases of solder, and due to the anisotropy of the materials. The fatigue life under thermomechanical cycling was significantly inferior to that obtained in isothermal mechanical cycling. A factor contributing to this inferiority is the internal damage produced during temperature cycling

  14. Effects of PCB thickness on adjustable fountain wave soldering

    Indian Academy of Sciences (India)

    hybrid circuit assembly, component lead tinning, and wire tinning. .... The mesh model was built and optimized with 599920 hybrid nodes as shown in figure 9. ... conducted to track the fluid motions of the two phases (i.e., molten solder and air).

  15. Microstructure and property measurements on in situ TiB2/70Si–Al composite for electronic packaging applications

    International Nuclear Information System (INIS)

    Zhang, L.; Gan, G.S.; Yang, B.

    2012-01-01

    Highlights: ► 2.0 wt.%TiB 2 /70Si–Al composite is prepared by a novel reactive technique. ► In situ TiB 2 particles can refine effectively the primary Si phase. ► The composite exhibited attractive physical and mechanical properties. -- Abstract: A novel reactive technique has been employed in fabrication of 2.0 wt.%TiB 2 /70Si–Al composite for electronic packaging applications. The microstructure and properties of composite were studied using scanning electron microscopy, energy dispersive X-ray spectrometer, coefficient of thermal expansion and thermal conductivity measurements, and 3-point bending tests. The results indicate that the in situ TiB 2 particles can effectively refine the primary Si phase. The property measurements results indicate that the 2.0 wt.%TiB 2 /70Si–Al composite has advantageous physical and mechanical properties, including low density, low coefficient of thermal expansion, high thermal conductivity, high Flexural strength and Brinell hardness.

  16. New Textile Sensors for In Situ Structural Health Monitoring of Textile Reinforced Thermoplastic Composites Based on the Conductive Poly(3,4-ethylenedioxythiophene-poly(styrenesulfonate Polymer Complex

    Directory of Open Access Journals (Sweden)

    Ivona Jerkovic

    2017-10-01

    Full Text Available Many metallic structural and non-structural parts used in the transportation industry can be replaced by textile-reinforced composites. Composites made from a polymeric matrix and fibrous reinforcement have been increasingly studied during the last decade. On the other hand, the fast development of smart textile structures seems to be a very promising solution for in situ structural health monitoring of composite parts. In order to optimize composites’ quality and their lifetime all the production steps have to be monitored in real time. Textile sensors embedded in the composite reinforcement and having the same mechanical properties as the yarns used to make the reinforcement exhibit actuating and sensing capabilities. This paper presents a new generation of textile fibrous sensors based on the conductive polymer complex poly(3,4-ethylenedioxythiophene-poly(styrenesulfonate developed by an original roll to roll coating method. Conductive coating for yarn treatment was defined according to the preliminary study of percolation threshold of this polymer complex. The percolation threshold determination was based on conductive dry films’ electrical properties analysis, in order to develop highly sensitive sensors. A novel laboratory equipment was designed and produced for yarn coating to ensure effective and equally distributed coating of electroconductive polymer without distortion of textile properties. The electromechanical properties of the textile fibrous sensors confirmed their suitability for in situ structural damages detection of textile reinforced thermoplastic composites in real time.

  17. An in situ carbonization-replication method to synthesize mesostructured WO3/C composite as nonprecious-metal anode catalyst in PEMFC.

    Science.gov (United States)

    Cui, Xiangzhi; Hua, Zile; Wei, Chenyang; Shu, Zhu; Zhang, Liangxia; Chen, Hangrong; Shi, Jianlin

    2013-02-01

    A meostructured WO(3)/C composite with crystalline framework and high electric conductivity has been synthesized by a new in situ carbonization-replication route using the block copolymer (poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)) present in situ in the pore channels of mesoporous silica template as carbon source. X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, thermogravimetry differential thermal analysis, and N(2) adsorption techniques were adopted for the structural characterization. Cyclic voltammetry, chronoamperometry, and single-cell test for hydrogen electrochemical oxidation were adopted to characterize the electrochemical activities of the mesoporous WO(3)/C composite. The carbon content and consequent electric conductivity of these high-surface-area (108-130 m(2) g(-1)) mesostructured WO(3)/C composite materials can be tuned by variation of the duration of heat treatment, and the composites exhibited high and stable electrochemical catalytic activity. The single-cell test results indicated that the mesostructured WO(3)/C composites showed clear electrochemical catalytic activity toward hydrogen oxidation at 25 °C, which makes them potential non-precious-metal anode catalysts in proton exchange membrane fuel cell. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Effect of homogeneity of particle distribution on tensile crack propagation in mushy state rolled in situ Al–4.5Cu–5TiB2 particulate composite

    International Nuclear Information System (INIS)

    Jana, A.; Siddhalingeshwar, I.G.; Mitra, R.

    2013-01-01

    The effect of mushy state rolling with 20 vol% liquid at 626 °C for 5% thickness reduction per pass on homogeneity of TiB 2 and CuAl 2 particle distribution in the in situ Al–4.5Cu–5TiB 2 composite has been examined. These particles, appearing as segregated at grain boundaries in the as-cast composite, are redistributed on mushy state rolling. The homogeneity of particle distribution has been quantitatively evaluated by developing a computer program for multi-scalar analysis of area-fractions in scanning electron microscope (SEM) images to estimate homogeneous length scales. The optimum homogeneity is found in the composite subjected to two mushy state roll passes. The matrix microhardness increases with decrease in the homogeneous length scale. In situ tensile straining experiments inside SEM have shown linkage of particle–matrix interfacial microcracks at particle-clusters as fracture mechanism in as-cast or 4-pass mushy state rolled composites. In contrast, crack propagation through matrix is favored in the 2-pass mushy state rolled composite

  19. Fabrication of SiC Composites with Synergistic Toughening of Carbon Whisker and In Situ 3C-SiC Nanowire

    Directory of Open Access Journals (Sweden)

    Zhang Yunlong

    2016-01-01

    Full Text Available The SiC composites with synergistic toughening of carbon whisker and in situ 3C-SiC nanowire have been fabricated by hot press sinter technology and annealed treatment technology. Effect of annealed time on the morphology of SiC nanowires and mechanical properties of the Cw/SiC composites was surveyed in detail. The appropriate annealed time improved mechanical properties of the Cw/SiC composites. The synergistic effect of carbon whisker and SiC nanowire can improve the fracture toughness for Cw/SiC composites. The vapor-liquid-solid growth (VLS mechanism was proposed. TEM photo showed that 3C-SiC nanowire can be obtained with preferential growth plane ({111}, which corresponded to interplanar spacing about 0.25 nm.

  20. Elevated-Temperature Mechanical Properties of Lead-Free Sn-0.7Cu- xSiC Nanocomposite Solders

    Science.gov (United States)

    Mohammadi, A.; Mahmudi, R.

    2018-02-01

    Mechanical properties of Sn-0.7 wt.%Cu lead-free solder alloy reinforced with 0 vol.%, 1 vol.%, 2 vol.%, and 3 vol.% 100-nm SiC particles have been assessed using the shear punch testing technique in the temperature range from 25°C to 125°C. The composite materials were fabricated by the powder metallurgy route by blending, compacting, sintering, and finally extrusion. The 2 vol.% SiC-containing composite showed superior mechanical properties. In all conditions, the shear strength was adversely affected by increasing test temperature, and the 2 vol.% SiC-containing composite showed superior mechanical properties. Depending on the test temperature, the shear yield stress and ultimate shear strength increased, respectively, by 3 MPa to 4 MPa and 4 MPa to 5.5 MPa, in the composite materials. The strength enhancement was mostly attributed to the Orowan particle strengthening mechanism due to the SiC nanoparticles, and to a lesser extent to the coefficient of thermal expansion mismatch between the particles and matrix in the composite solder. A modified shear lag model was used to predict the total strengthening achieved by particle addition, based on the contribution of each of the above mechanisms.

  1. Electrochemical Behavior of Sn-9Zn- xTi Lead-Free Solders in Neutral 0.5M NaCl Solution

    Science.gov (United States)

    Wang, Zhenghong; Chen, Chuantong; Jiu, Jinting; Nagao, Shijo; Nogi, Masaya; Koga, Hirotaka; Zhang, Hao; Zhang, Gong; Suganuma, Katsuaki

    2018-05-01

    Electrochemical techniques were employed to study the electrochemical corrosion behavior of Sn-9Zn- xTi ( x = 0, 0.05, 0.1, 0.2 wt.%) lead-free solders in neutral 0.5M NaCl solution, aiming to figure out the effect of Ti content on the corrosion properties of Sn-9Zn, providing information for the composition design of Sn-Zn-based lead-free solders from the perspective of corrosion. EIS results reveal that Ti addition was involved in the corrosion product layer and changed electrochemical interface behavior from charge transfer control process to diffusion control process. The trace amount of Ti addition (0.05 wt.%) can refine the microstructure and improve the corrosion resistance of Sn-9Zn solder, evidenced by much lower corrosion current density ( i corr) and much higher total resistance ( R t). Excess Ti addition (over 0.1 wt.%) led to the formation of Ti-containing IMCs, which were confirmed as Sn3Ti2 and Sn5Ti6, deteriorating the corrosion resistance of Sn-9Zn- xTi solders. The main corrosion products were confirmed as Sn3O(OH)2Cl2 mixed with small amount of chlorine/oxide Sn compounds.

  2. In-situ studies of stress- and magnetic-field-induced phase transformation in a polymer-bonded Ni-Co-Mn-In composite

    International Nuclear Information System (INIS)

    Liu, D.M.; Nie, Z.H.; Wang, G.; Wang, Y.D.; Brown, D.E.; Pearson, J.; Liaw, P.K.; Ren, Y.

    2010-01-01

    A polymer-bonded Ni 45 Co 5 Mn 36.6 In 13.4 ferromagnetic shape-memory composite was fabricated, having magnetic-field-driven shape recovery properties. The thermo-magnetization curves of the composite suggested that the magnetic-field-induced reverse martensitic transformation occurs in the composite. The effects of temperature, stress, and magnetic-field on the phase transformation properties were systematically investigated using an in-situ high-energy X-ray diffraction technique. A temperature-induced reversible martensitic phase transformation was confirmed within the composite, showing a broad phase transformation interval. Stress-induced highly textured martensite was observed in the composite during uniaxial compressive loading, with a residual strain after unloading. The origin of the textured martensite can be explained by the grain-orientation-dependent Bain distortion energy. A recovery strain of ∼1.76% along the compression direction was evidenced in the pre-strained composite with an applied magnetic-field of 5 T. This recovery was caused by the magnetic-field-induced reverse martensitic phase transformation. The phase transformation properties of the ferromagnetic shape-memory composite, different from its bulk alloys, can be well explained by the Clausius-Clapeyron relation. The large magnetic-field-induced strain, together with good ductility and low cost, make the polymer-bonded Ni-Co-Mn-In composites potential candidates for magnetic-field-driven actuators.

  3. Structure, thermal and mechanical properties of in situ Al-based metal matrix composite reinforced with Al2O3 and TiC submicron particles

    International Nuclear Information System (INIS)

    Yu Peng; Mei Zhi; Tjong, S.C.

    2005-01-01

    We report herein the structure and characterization of in situ Al-based metal matrix composites (MMCs) prepared from the Al-10 wt.% TiO 2 and Al-10 wt.% TiO 2 -1.5 wt.% C systems via hot isostatic pressing (HIP) at 1000 deg C and 100 MPa. The structure, morphology and thermal behavior of HIPed samples were studied by means of the X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results indicated that fined Al 2 O 3 particles and large intermetallic Al 3 Ti plates were in situ formed in the Al-10 wt.% TiO 2 sample during HIPing. However, the introduction of C to the Al-TiO 2 system was beneficial to eliminate large intermetallic Al 3 Ti plates. In this case, Al 2 O 3 and TiC submicron particles were in situ formed in the Al-10 wt.% TiO 2 -1.5 wt.% C sample. Three-point-bending test showed that the strength and the strain-at-break of the HIPed Al-10 wt.% TiO 2 -1.5 wt.% C sample were significantly higher than those of its Al-10 wt.% TiO 2 counterpart. The improvement was derived from the elimination of bulk Al 3 Ti intermetallic plates and from the formation of TiC submicron particles. DSC measurements and thermodynamic analyses were carried out to reveal the reaction formation mechanisms of in situ reinforcing phases. The DSC results generally correlated well with the theoretical predictions. Finally, the correlation between the structure-property relationships of in situ composites is discussed

  4. Bi-functional Au/FeS (Au/Co{sub 3}O{sub 4}) composite for in situ SERS monitoring and degradation of organic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Shuzhen; Cai, Qian; Lu, Kailing; Liao, Fan, E-mail: fliao@suda.edu.cn; Shao, Mingwang, E-mail: mwshao@suda.edu.cn [Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University (China)

    2016-01-15

    The bi-functional Au/FeS (Au/Co{sub 3}O{sub 4}) composite was fabricated by in situ reducing Au nanoparticles onto the surface of FeS (Co{sub 3}O{sub 4}). The as-prepared FeS possessed a multi-structure composed of plenty of nanoplates, which were coated by Au nanoparticles with an average size of ∼47.5 nm. While the Co{sub 3}O{sub 4} showed a thin hexagonal sheet containing Au nanoparticles on its surface with an average size of ∼79.0 nm. Both the as-prepared Au/FeS and Au/Co{sub 3}O{sub 4} composites exhibited excellent SERS performance, capable of enhancing the Raman signals of R6G molecules with the enhancement factor up to 1.81 × 10{sup 6} and 7.60 × 10{sup 4}, respectively. Moreover, Au/FeS (Au/Co{sub 3}O{sub 4}) composite also has been verified to have intrinsic peroxidase-like activity, which could decompose H{sub 2}O{sub 2} into hydroxyl radicals and then degrade organic pollutants into small molecules. Therefore, SERS can be used to real-time and in situ monitoring the degradation process of R6G molecules, employing the Au/FeS (Au/Co{sub 3}O{sub 4}) composite both as SERS substrate and catalyst. Graphical abstract: SERS was used to real-time and in situ monitoring the degradation of R6G, employing the Au/FeS and Au/Co{sub 3}O{sub 4} composites both as SERS substrates and catalysts.

  5. Diurnal variability in riverine dissolved organic matter composition determined by in situ optical measurement in the San Joaquin River (California, USA)

    Science.gov (United States)

    Spencer, R.G.M.; Pellerin, B.A.; Bergamaschi, B.A.; Downing, B.D.; Kraus, T.E.C.; Smart, D.R.; Dahlgren, R.A.; Hernes, P.J.

    2007-01-01

    Dissolved organic matter (DOM) concentration and composition in riverine and stream systems are known to vary with hydrological and productivity cycles over the annual and interannual time scales. Rivers are commonly perceived as homogeneous with respect to DOM concentration and composition, particularly under steady flow conditions over short time periods. However, few studies have evaluated the impact of short term variability ( DOC) measurement alone. The in situ optical measurements described in this study clearly showed for the first time diurnal variations in DOM measurements, which have previously been related to both composition and concentration, even though diurnal changes were not well reflected in bulk DOC concentrations. An apparent asynchronous trend of DOM absorbance and chlorophyll-a in comparison to chromophoric dissolved organic matter (CDOM) fluorescence and spectral slope S290-350 suggests that no one specific CDOM spectrophotometric measurement explains absolutely DOM diurnal variation in this system; the measurement of multiple optical parameters is therefore recommended. The observed diurnal changes in DOM composition, measured by in situ optical instrumentation likely reflect both photochemical and biologically-mediated processes. The results of this study highlight that short-term variability in DOM composition may complicate trends for studies aiming to distinguish different DOM sources in riverine systems and emphasizes the importance of sampling specific study sites to be compared at the same time of day. The utilization of in situ optical technology allows short-term variability in DOM dynamics to be monitored and serves to increase our understanding of its processing and fundamental role in the aquatic environment. Copyright ?? 2007 John Wiley & Sons, Ltd.

  6. Soldering Characteristics and Mechanical Properties of Sn-1.0Ag-0.5Cu Solder with Minor Aluminum Addition

    Directory of Open Access Journals (Sweden)

    Yee Mei Leong

    2016-06-01

    Full Text Available Driven by the trends towards miniaturization in lead free electronic products, researchers are putting immense efforts to improve the properties and reliabilities of Sn based solders. Recently, much interest has been shown on low silver (Ag content solder SAC105 (Sn-1.0Ag-0.5Cu because of economic reasons and improvement of impact resistance as compared to SAC305 (Sn-3.0Ag-0.5Cu. The present work investigates the effect of minor aluminum (Al addition (0.1–0.5 wt.% to SAC105 on the interfacial structure between solder and copper substrate during reflow. The addition of minor Al promoted formation of small, equiaxed Cu-Al particle, which are identified as Cu3Al2. Cu3Al2 resided at the near surface/edges of the solder and exhibited higher hardness and modulus. Results show that the minor addition of Al does not alter the morphology of the interfacial intermetallic compounds, but they substantially suppress the growth of the interfacial Cu6Sn5 intermetallic compound (IMC after reflow. During isothermal aging, minor alloying Al has reduced the thickness of interfacial Cu6Sn5 IMC but has no significant effect on the thickness of Cu3Sn. It is suggested that of atoms of Al exert their influence by hindering the flow of reacting species at the interface.

  7. Soldering Characteristics and Mechanical Properties of Sn-1.0Ag-0.5Cu Solder with Minor Aluminum Addition

    Science.gov (United States)

    Leong, Yee Mei; Haseeb, A.S.M.A.

    2016-01-01

    Driven by the trends towards miniaturization in lead free electronic products, researchers are putting immense efforts to improve the properties and reliabilities of Sn based solders. Recently, much interest has been shown on low silver (Ag) content solder SAC105 (Sn-1.0Ag-0.5Cu) because of economic reasons and improvement of impact resistance as compared to SAC305 (Sn-3.0Ag-0.5Cu. The present work investigates the effect of minor aluminum (Al) addition (0.1–0.5 wt.%) to SAC105 on the interfacial structure between solder and copper substrate during reflow. The addition of minor Al promoted formation of small, equiaxed Cu-Al particle, which are identified as Cu3Al2. Cu3Al2 resided at the near surface/edges of the solder and exhibited higher hardness and modulus. Results show that the minor addition of Al does not alter the morphology of the interfacial intermetallic compounds, but they substantially suppress the growth of the interfacial Cu6Sn5 intermetallic compound (IMC) after reflow. During isothermal aging, minor alloying Al has reduced the thickness of interfacial Cu6Sn5 IMC but has no significant effect on the thickness of Cu3Sn. It is suggested that of atoms of Al exert their influence by hindering the flow of reacting species at the interface. PMID:28773645

  8. Effects of soldering methods on tensile strength of a gold-palladium metal ceramic alloy.

    Science.gov (United States)

    Ghadhanfari, Husain A; Khajah, Hasan M; Monaco, Edward A; Kim, Hyeongil

    2014-10-01

    The tensile strength obtained by conventional postceramic application soldering and laser postceramic welding may require more energy than microwave postceramic soldering, which could provide similar tensile strength values. The purpose of the study was to compare the tensile strength obtained by microwave postceramic soldering, conventional postceramic soldering, and laser postceramic welding. A gold-palladium metal ceramic alloy and gold-based solder were used in this study. Twenty-seven wax specimens were cast in gold-palladium noble metal and divided into 4 groups: laser welding with a specific postfiller noble metal, microwave soldering with a postceramic solder, conventional soldering with the same postceramic solder used in the microwave soldering group, and a nonsectioned control group. All the specimens were heat treated to simulate a normal porcelain sintering sequence. An Instron Universal Testing Machine was used to measure the tensile strength for the 4 groups. The means were analyzed statistically with 1-way ANOVA. The surface and fracture sites of the specimens were subjectively evaluated for fracture type and porosities by using a scanning electron microscope. The mean (standard deviation) ultimate tensile strength values were as follows: nonsectioned control 818 ±30 MPa, microwave 516 ±34 MPa, conventional 454 ±37 MPa, and laser weld 191 ±39 MPa. A 1-way ANOVA showed a significant difference in ultimate tensile strength among the groups (F3,23=334.5; Ptensile strength for gold and palladium noble metals than either conventional soldering or laser welding. Conventional soldering resulted in a higher tensile strength than laser welding. Under the experimental conditions described, either microwave or conventional postceramic soldering would appear to satisfy clinical requirements related to tensile strength. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  9. Synthesis and characterization of polypropylene/graphite nano composite preparation for in situ polymerization; Sintese e caracterizacao de nanocompositos polipropileno/grafite obtidos pela polimerizacao in situ

    Energy Technology Data Exchange (ETDEWEB)

    Montagna, L.S.; Fim, F. de C.; Galland, G.B. [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica; Basso, N.R.S., E-mail: nrbass@pucrs.b [Pontificia Universidade Catolica do Rio Grande do Sul (PUC-RS), Porto Alegre, RS (Brazil)

    2010-07-01

    This paper presents the synthesis of polypropylene/graphite nanocomposites through in situ polymerization, using the metallocene catalyst C{sub 20}H{sub 16}Cl{sub 2}Zr (dichloro(rac-ethylenebis(indenyl))zircon(IV)). The graphite nanosheets in nano dimensions were added to the polymer matrix in percentages of 0.6;1.0;4.2;4.8 and 6.0% (w/w). The TEM images indicated that the thickness of graphite nanosheets ranged from 4 to 60 nm and by means of XRD analysis it was observed that the physical and chemical treatment did not destroyed the graphite layers. The presence of nanosheets did not decrease the catalytic activity of the nanocomposites. TEM images and XRD analysis of nanocomposites showed a good dispersion of the graphite nanosheets in the polypropylene matrix. (author)

  10. Facile in situ hydrothermal synthesis of g-C{sub 3}N{sub 4}/SnS{sub 2} composites with excellent visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Fang; Zhao, Lina; Pei, Xule [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang 330063 (China); College of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Xubiao, E-mail: luoxubiao@126.com [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang 330063 (China); College of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Shenglian, E-mail: sllou@hnu.edu.cn [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang 330063 (China); College of Environmental and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2017-03-01

    The g-C{sub 3}N{sub 4}/SnS{sub 2} composites were prepared by in situ hydrothermal method, and the effect of g-C{sub 3}N{sub 4} content on the physical and chemical properties, and photocatalytic performance of g-C{sub 3}N{sub 4}/SnS{sub 2} composites was investigated. The introduction of g-C{sub 3}N{sub 4} enhanced the visible-light absorption of SnS{sub 2}, and reduced the recombination rate of electron-hole pairs. The photocatalytic performance of g-C{sub 3}N{sub 4}/SnS{sub 2} composites was also obviously influenced by g-C{sub 3}N{sub 4} content, and it was found that 15% g-C{sub 3}N{sub 4}/SnS{sub 2} composite exhibited the highest photocatalytic activity and excellent regeneration, which was attributed to the most efficient charge separation, the largest specific surface area and the formation of dominant active species (h{sup +} and ·O{sub 2}{sup −} radicals) during the photocatalytic process. - Graphical abstract: Photocatalytic mechanism of g-C{sub 3}N{sub 4}/SnS{sub 2} composites. - Highlights: • g-C{sub 3}N{sub 4}/SnS{sub 2} composites were fabricated by a in situ hydrothermal process. • g-C{sub 3}N{sub 4} content was optimized, and the optimal g-C{sub 3}N{sub 4} content is 15%. • 15% g-C{sub 3}N{sub 4}/SnS{sub 2} shows the highest visible-light photocatalytic activity. • g-C{sub 3}N{sub 4}/SnS{sub 2} composites exhibit excellent reusability.

  11. In situ synthesized TiB-TiN reinforced Ti6Al4V alloy composite coatings: microstructure, tribological and in-vitro biocompatibility.

    Science.gov (United States)

    Das, Mitun; Bhattacharya, Kaushik; Dittrick, Stanley A; Mandal, Chitra; Balla, Vamsi Krishna; Sampath Kumar, T S; Bandyopadhyay, Amit; Manna, Indranil

    2014-01-01

    Wear resistant TiB-TiN reinforced Ti6Al4V alloy composite coatings were deposited on Ti substrate using laser based additive manufacturing technology. Ti6Al4V alloy powder premixed with 5wt% and 15wt% of boron nitride (BN) powder was used to synthesize TiB-TiN reinforcements in situ during laser deposition. Influences of laser power, scanning speed and concentration of BN on the microstructure, mechanical, in vitro tribological and biological properties of the coatings were investigated. Microstructural analysis of the composite coatings showed that the high temperature generated due to laser interaction with Ti6Al4V alloy and BN results in situ formation of TiB and TiN phases. With increasing BN concentration, from 5wt% to 15wt%, the Young's modulus of the composite coatings, measured by nanoindentation, increased from 170±5GPa to 204±14GPa. In vitro tribological tests showed significant increase in the wear resistance with increasing BN concentration. Under identical test conditions TiB-TiN composite coatings with 15wt% BN exhibited an order of magnitude less wear rate than CoCrMo alloy-a common material for articulating surfaces of orthopedic implants. Average top surface hardness of the composite coatings increased from 543±21HV to 877±75HV with increase in the BN concentration. In vitro biocompatibility and flow cytometry study showed that these composite coatings were non-toxic, exhibit similar cell-materials interactions and biocompatibility as that of commercially pure titanium (CP-Ti) samples. In summary, excellent in vitro wear resistance, high stiffness and suitable biocompatibility make these composite coatings as a potential material for load-bearing articulating surfaces towards orthopaedic implants. © 2013 Elsevier Ltd. All rights reserved.

  12. Soldering-induced Cu diffusion and intermetallic compound formation between Ni/Cu under bump metallization and SnPb flip-chip solder bumps

    Science.gov (United States)

    Huang, Chien-Sheng; Jang, Guh-Yaw; Duh, Jenq-Gong

    2004-04-01

    Nickel-based under bump metallization (UBM) has been widely used as a diffusion barrier to prevent the rapid reaction between the Cu conductor and Sn-based solders. In this study, joints with and without solder after heat treatments were employed to evaluate the diffusion behavior of Cu in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure. The atomic flux of Cu diffused through Ni was evaluated from the concentration profiles of Cu in solder joints. During reflow, the atomic flux of Cu was on the order of 1015-1016 atoms/cm2s. However, in the assembly without solder, no Cu was detected on the surface of Ni even after ten cycles of reflow. The diffusion behavior of Cu during heat treatments was studied, and the soldering-process-induced Cu diffusion through Ni metallization was characterized. In addition, the effect of Cu content in the solder near the solder/intermetallic compound (IMC) interface on interfacial reactions between the solder and the Ni/Cu UBM was also discussed. It is evident that the (Cu,Ni)6Sn5 IMC might form as the concentration of Cu in the Sn-Cu-Ni alloy exceeds 0.6 wt.%.

  13. Compression Properties and Electrical Conductivity of In-Situ 20 vol.% Nano-Sized TiCx/Cu Composites with Different Particle Size and Morphology.

    Science.gov (United States)

    Zhang, Dongdong; Bai, Fang; Sun, Liping; Wang, Yong; Wang, Jinguo

    2017-05-04

    The compression properties and electrical conductivity of in-situ 20 vol.% nano-sized TiC x /Cu composites fabricated via combustion synthesis and hot press in Cu-Ti-CNTs system at various particles size and morphology were investigated. Cubic-TiC x /Cu composite had higher ultimate compression strength (σ UCS ), yield strength (σ 0.2 ), and electric conductivity, compared with those of spherical-TiC x /Cu composite. The σ UCS , σ 0.2 , and electrical conductivity of cubic-TiC x /Cu composite increased by 4.37%, 20.7%, and 17.8% compared with those of spherical-TiC x /Cu composite (526 MPa, 183 MPa, and 55.6% International Annealed Copper Standard, IACS). Spherical-TiC x /Cu composite with average particle size of ~94 nm exhibited higher ultimate compression strength, yield strength, and electrical conductivity compared with those of spherical-TiC x /Cu composite with 46 nm in size. The σ UCS , σ 0.2 , and electrical conductivity of spherical-TiC x /Cu composite with average size of ~94 nm in size increased by 17.8%, 33.9%, and 62.5% compared with those of spherical-TiC x /Cu composite (417 MPa, 121 MPa, and 40.3% IACS) with particle size of 49 nm, respectively. Cubic-shaped TiC x particles with sharp corners and edges led to stress/strain localization, which enhanced the compression strength of the composites. The agglomeration of spherical-TiC x particles with small size led to the compression strength reduction of the composites.

  14. Microwave-assisted in situ synthesis of reduced graphene oxide-BiVO{sub 4} composite photocatalysts and their enhanced photocatalytic performance for the degradation of ciprofloxacin

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yan [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Sun, Shaofang [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); School of Environmental Science and Engineering, Chang’an University, Yanta Road 126, Xi’an, 710054 (China); Song, Yang; Yan, Xu [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Guan, Weisheng [School of Environmental Science and Engineering, Chang’an University, Yanta Road 126, Xi’an, 710054 (China); Liu, Xinlin [School of Material Science and Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Shi, Weidong, E-mail: swd1978@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China)

    2013-04-15

    Highlights: ► Microwave-assisted in situ growth of RGO-BiVO{sub 4} composite was proposed. ► A relatively small particle size with organic-additives free. ► Graphene was formed during the microwave-heating by oxygen capture. ► GB-2 sample exhibits the highest CIP degradation ratio (3 times over pure BiVO{sub 4}). ► The enhancements of activities result from the effective charge separation. -- Abstract: To improve the photodegradation efficiency for ciprofloxacin (CIP), a new-type microwave-assisted in situ growth method is developed for the preparation of reduced graphene oxide (RGO) -BiVO{sub 4} composite photocatalysts. The as-produced RGO-BiVO{sub 4} composite photocatalysts show extremely high enhancement of CIP degradation ratio over the pure BiVO{sub 4} photocatalyst under visible light. Specially, the 2 wt% RGO-BiVO{sub 4} composite photocatalyst exhibits the highest CIP degradation ratio (68.2%) in 60 min, which is over 3 times than that (22.7%) of the pure BiVO{sub 4} particles. The enhancement of photocatalytic activities of RGO-BiVO{sub 4} photocatalysts can be attributed to the effective separation of electron–hole pairs rather than the improvement of light absorption.

  15. Conductive additive content balance in Li-ion battery cathodes: Commercial carbon blacks vs. in situ carbon from LiFePO{sub 4}/C composites

    Energy Technology Data Exchange (ETDEWEB)

    Palomares, Veronica; Goni, Aintzane; Muro, Izaskun Gil de; Rojo, Teofilo [Departamento de Quimica Inorganica, Universidad del Pais Vasco UPV/EHU, P.O. Box. 644, 48080, Bilbao (Spain); de Meatza, Iratxe; Bengoechea, Miguel [Energy Department, CIDETEC-IK4, P Miramon 196, Parque Tecnologico de San Sebastian, 20009, San Sebastian (Spain); Cantero, Igor [Departamento I+D+i Nuevas Tecnologias, CEGASA, Artapadura, 11, 01013 Vitoria-Gasteiz (Spain)

    2010-11-15

    Two samples of commercial conducting carbon black and the carbon generated in situ during LiFePO{sub 4}/C composite synthesis from citric acid are studied, with the aim of finding out whether carbon from the composite can fulfil the same function as carbon black in the electrode blend for a Li-ion battery. For this purpose, the carbon samples are analyzed by several techniques, such as X-ray diffraction, Raman spectroscopy, transmission electron microscopy, granulometry, BET specific area and conductivity measurements. Different cathode compositions and component proportions are tested for pellet and cast electrodes. Electrochemical results show that a moderate reduction of commercial carbon black content in both kinds of cathodes, by adding more LiFePO{sub 4}/C composite, enhanced the electrochemical behaviour by around 10%. In situ generated carbon can partially replace commercial conducting carbon black because its high specific surface probably enhances electrolyte penetration into the cathode, but it is always necessary to maintain a minimum amount of carbon black that provides better conductivity in order to obtain a good electrochemical response. (author)

  16. Electrically and Thermally Conductive Carbon Fibre Fabric Reinforced Polymer Composites Based on Nanocarbons and an In-situ Polymerizable Cyclic Oligoester.

    Science.gov (United States)

    Jang, Ji-Un; Park, Hyeong Cheol; Lee, Hun Su; Khil, Myung-Seob; Kim, Seong Yun

    2018-05-16

    There is growing interest in carbon fibre fabric reinforced polymer (CFRP) composites based on a thermoplastic matrix, which is easy to rapidly produce, repair or recycle. To expand the applications of thermoplastic CFRP composites, we propose a process for fabricating conductive CFRP composites with improved electrical and thermal conductivities using an in-situ polymerizable and thermoplastic cyclic butylene terephthalate oligomer matrix, which can induce good impregnation of carbon fibres and a high dispersion of nanocarbon fillers. Under optimal processing conditions, the surface resistivity below the order of 10 +10 Ω/sq, which can enable electrostatic powder painting application for automotive outer panels, can be induced with a low nanofiller content of 1 wt%. Furthermore, CFRP composites containing 20 wt% graphene nanoplatelets (GNPs) were found to exhibit an excellent thermal conductivity of 13.7 W/m·K. Incorporating multi-walled carbon nanotubes into CFRP composites is more advantageous for improving electrical conductivity, whereas incorporating GNPs is more beneficial for enhancing thermal conductivity. It is possible to fabricate the developed thermoplastic CFRP composites within 2 min. The proposed composites have sufficient potential for use in automotive outer panels, engine blocks and other mechanical components that require conductive characteristics.

  17. Thermal and mechanical properties of palm oil-based polyurethane acrylate/ clay nano composites prepared by in-situ intercalative method and electron beam radiation

    International Nuclear Information System (INIS)

    Salih, A.M.; Mansor Ahmad; Nor Azowa Ibrahim; Rida Tajau; Wan Mohd Zin Wan Yunus

    2013-01-01

    Full-text: Palm oil based-polyurethane acrylate (POBUA)/ clay nano composites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4 ' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5 % wt), and then subjected to polycondensation reaction with MDI. Nano composites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nano clay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Angstrom, while the structure morphology of the nano composites was investigated by TEM and SEM. The nano composites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nano composites was significantly increased by incorporation of nano clay into the polymer matrix. DSC results reveal that the T g was shifted to higher values, gradually with increasing the amount of filler in the nano composites. Tensile strength and Young's modulus of the nano composites showed remarkable improvement compared to the neat POBUA. (author)

  18. An Equation-of-State Compositional In-Situ Combustion Model: A Study of Phase Behavior Sensitivity

    DEFF Research Database (Denmark)

    Kristensen, Morten Rode; Gerritsen, M. G.; Thomsen, Per Grove

    2009-01-01

    phase behavior sensitivity for in situ combustion, a thermal oil recovery process. For the one-dimensional model we first study the sensitivity to numerical discretization errors and provide grid density guidelines for proper resolution of in situ combustion behavior. A critical condition for success...... to ignition. For a particular oil we show that the simplified approach overestimates the required air injection rate for sustained front propagation by 17% compared to the equation of state-based approach....

  19. In situ formation of ZrB2 particulates and their influence on microstructure and tensile behavior of AA7075 aluminum matrix composites

    Directory of Open Access Journals (Sweden)

    J. David Raja Selvam

    2017-02-01

    Full Text Available In situ synthesis of aluminum matrix composites (AMCs has become a popular method due to several advantages over conventional stir casting method. In the present study, AA7075/ZrB2 AMCs reinforced with various content of ZrB2 particulates (0, 3, 6, 9 and 12 wt.% were synthesized by the in situ reaction of molten aluminum with inorganic salts K2ZrF6 and KBF4. The composites were characterized using XRD, OM, SEM, EBSD and TEM. The XRD patterns revealed the formation of ZrB2 particulates without the presence of any other compounds. The formation of ZrB2 particulates refined the grains of aluminum matrix extensively. Most of the ZrB2 particulates were located near the grain boundaries. The ZrB2 particulates exhibited various morphologies including spherical, cylindrical and hexagonal shapes. The size of the ZrB2 particulates was in the order of nano, sub micron and micron level. A good interfacial bonding was observed between the aluminum matrix and the ZrB2 particulates. The in situ formed ZrB2 particulates enhanced the mechanical properties such as microhardness and the ultimate tensile strength. Various strengthening mechanisms were identified.

  20. Effect of different oxidants on polyaniline/single walled carbon nanotubes composites synthesized via ultrasonically initiated in-situ chemical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Gull, Nafisa, E-mail: gullchemist@gmail.com [Department of Polymer Engineering and Technology, University of the Punjab, Lahore, 54590 (Pakistan); Khan, Shahzad Maqsood, E-mail: shahzadkhan81@hotmail.com [Department of Polymer Engineering and Technology, University of the Punjab, Lahore, 54590 (Pakistan); Islam, Atif; Zia, Saba; Shafiq, Muhammad; Sabir, Aneela; Munawar, Muhammad Azeem [Department of Polymer Engineering and Technology, University of the Punjab, Lahore, 54590 (Pakistan); Butt, Muhammad Taqi Zahid [College of Engineering and Emerging Technologies, University of the Punjab, Lahore, 54590 (Pakistan); Jamil, Tahir [Department of Polymer Engineering and Technology, University of the Punjab, Lahore, 54590 (Pakistan)

    2016-04-01

    This study is aimed at investigating the effect of different oxidants on properties of polyaniline/single walled carbon nanotubes (PANI/SWCNT) composites and scrutinizing a suitable oxidant to improve the properties of composites. PANI/SWCNT composites were fabricated via ultrasonically initiated in-situ chemical polymerization technique using four different oxidants; hydrogen peroxide (H{sub 2}O{sub 2}), ammonium peroxidisulphate ((NH{sub 4}){sub 2}S{sub 2}O{sub 8}), potassium dichromate (K{sub 2}Cr{sub 2}O{sub 7}) and potassium iodate (KIO{sub 3}). Percent yield (97%), molecular weight (45532 g mol{sup −1}) and electrical conductivity (0.835 S cm{sup −1}) were found maximum for composite prepared in the presence of H{sub 2}O{sub 2}. Structural confirmation of PANI and charge transfer complex formation between PANI and SWCNT were confirmed by fourier transform infrared spectroscopy, UV–visible spectroscopy and X-ray diffraction spectroscopy. Thermogravimetric analysis verified that the PANI/SWCNT composite synthesized using H{sub 2}O{sub 2} had maximum thermal stability with least thermal degradation (∼28%). Minimal thermal transitions of the composite were also observed for same composite by differential scanning calorimetry. Scanning electron microscopic images of PANI/SWCNT composites revealed that SWCNT were properly dispersed in PANI matrix when H{sub 2}O{sub 2} was used. Above results provide the valuable suggestion that; H{sub 2}O{sub 2} is a promising oxidant to enhance structural, thermal, electrical and microscopic properties of composites. - Highlights: • Ultrasonically initiated in-situ chemical polymerization protocol was devised for synthesis of PANI/SWCNT composites. • SEM micrographs of PANI/SWCNT-1 showed uniform dispersed structure. • Better thermal stability and conductivity was evidenced for H{sub 2}O{sub 2} based PANI/SWCNT composite. • π–π interaction between PANI and SWCNT is confirmed by FTIR and UV

  1. Microwave-assisted in situ synthesis of reduced graphene oxide-BiVO4 composite photocatalysts and their enhanced photocatalytic performance for the degradation of ciprofloxacin.

    Science.gov (United States)

    Yan, Yan; Sun, Shaofang; Song, Yang; Yan, Xu; Guan, Weisheng; Liu, Xinlin; Shi, Weidong

    2013-04-15

    To improve the photodegradation efficiency for ciprofloxacin (CIP), a new-type microwave-assisted in situ growth method is developed for the preparation of reduced graphene oxide (RGO) -BiVO4 composite photocatalysts. The as-produced RGO-BiVO4 composite photocatalysts show extremely high enhancement of CIP degradation ratio over the pure BiVO4 photocatalyst under visible light. Specially, the 2 wt% RGO-BiVO4 composite photocatalyst exhibits the highest CIP degradation ratio (68.2%) in 60 min, which is over 3 times than that (22.7%) of the pure BiVO4 particles. The enhancement of photocatalytic activities of RGO-BiVO4 photocatalysts can be attributed to the effective separation of electron-hole pairs rather than the improvement of light absorption. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. High Dielectric Constant Study of TiO2-Polypyrrole Composites with Low Contents of Filler Prepared by In Situ Polymerization

    Directory of Open Access Journals (Sweden)

    Khalil Ahmed

    2016-01-01

    Full Text Available TiO2/polypyrrole composites with high dielectric constant have been synthesized by in situ polymerization of pyrrole in an aqueous dispersion of low concentration of TiO2, in the presence of small amount of HCl. Structural, optical, surface morphological, and thermal properties of the composites were investigated by X-ray diffractometer, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, and thermogravimetric analysis, respectively. The data obtained from diffractometer and thermal gravimetric analysis confirmed the crystalline nature and thermal stability of the prepared composites. The dielectric constant of 5 wt% TiO2 increased with filler content up to 4.3 × 103 at 1 kHz and then decreased to 1.25 × 103 at 10 kHz.

  3. Al-TiC in situ composite coating fabricated by low power pulsed laser cladding on AZ91D magnesium alloy

    Science.gov (United States)

    Yang, Liuqing; Li, Zhiyong; Zhang, Yingqiao; Wei, Shouzheng; Liu, Fuqiang

    2018-03-01

    Al + (Ti + B4C) composite coating was cladded on AZ91D magnesium alloy by a low power pulsed Nd-YAG laser. The Ti+B4C mixed powder is with the ratio of Ti: B4C = 5:1, which was then mixed with Al powder by weight fraction of 10%, 15% and 20%, respectively. Scanning electron microscopy, energy dispersive spectrometer and X-ray diffraction were used to study the microstructure, chemical composition and phase composition of the coating. Results showed that the coating had satisfied metallurgical bonding with the magnesium substrate. Al3Mg2, Al12Mg17, Al3Ti and TiC were formed by in-situ reaction. The coatings have micro-hardness of 348HV, which is about 5-6 times higher than that of AZ91D. The wear resistance and corrosion resistance of the coatings are enhanced with the addition of the mixed powder.

  4. Effect of nano Co reinforcements on the structure of the Sn-3.0Ag-0.5Cu solder in liquid and after reflow solid states

    Energy Technology Data Exchange (ETDEWEB)

    Yakymovych, Andriy, E-mail: yakymovych@univie.ac.at [Department of Inorganic Chemistry – Functional Materials, University of Vienna, Währinger Str. 42, 1090 Vienna (Austria); Department of Metal Physics, Ivan Franko National University of Lviv, Kyrylo i Mephodiy Str. 8, 79005 Lviv (Ukraine); Mudry, Stepan; Shtablavyi, Ihor [Department of Metal Physics, Ivan Franko National University of Lviv, Kyrylo i Mephodiy Str. 8, 79005 Lviv (Ukraine); Ipser, Herbert [Department of Inorganic Chemistry – Functional Materials, University of Vienna, Währinger Str. 42, 1090 Vienna (Austria)

    2016-09-15

    Sn-Ag-Cu (SAC) alloys are commonly recognized as lead-free solders employed in the electronics industry. However, some disadvantages in mechanical properties and their higher melting temperatures compared to Pb-Sn solders prompt new research relating to reinforcement of existing SAC solders. One of the ways to reinforce these solder materials is the formation of composites with nanoparticles as filler materials. Accordingly, this study presents structural features of nanocomposite (Sn-3.0Ag-0.5Cu){sub 100−x}(nanoCo){sub x} solders with up to 0.8 wt% nano Co. The effect of nano-sized Co particles was investigated by means of differential thermal analysis (DTA), X-ray diffraction (XRD) in both liquid and solid states, and scanning electron microscopy (SEM). The experimental data of DTA are compared with available literature data for bulk Sn-3.0Ag-0.5Cu alloy to check the capability of minor nano-inclusions to decrease the melting temperature of the SAC solder. The combination of structural data in liquid and solid states provides important information about the structural transformations of liquid Sn-3.0Ag-0.5Cu alloys caused by minor Co additions and the phase formation during crystallization. Furthermore, scanning electron microscopy has shown the mutual substitution of Co and Cu atoms in the Cu{sub 6}Sn{sub 5} and CoSn{sub 3} phases, respectively. - Highlights: • Differential thermal analysis of nanocomposite (Sn-3.0Ag-0.5Cu){sub 100−x}(nanoCo){sub x} alloys. • Structural transformations of liquid Sn-3.0Ag-0.5Cu solder by minor Co additions. • Structure data of the solid quaternary (Sn-3.0Ag-0.5Cu){sub 100−x}(Co){sub x} alloys. • Substitution of Co and Cu atoms in the Cu{sub 6}Sn{sub 5} and CoSn{sub 3} phases.

  5. Thermal Analysis of the Sn-Ag-Cu-In Solder Alloy

    DEFF Research Database (Denmark)

    Sopousek, J.; Palcut, Marián; Hodúlová, Erika

    2010-01-01

    The tin-based alloy Sn-1.5Ag-0.7Cu-9.5In (composition in wt.%) is a potential candidate for lead-free soldering at temperatures close to 200°C due to the significant amount of indium. Samples of Sn-1.5Ag-0.7Cu-9.5In were prepared by controlled melting of the pure elements, followed by quenching...... to room temperature. The samples were analyzed by scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDS) and electron backscatter diffraction. The solidified melt consisted of four different phases. Solidification behavior was monitored by heat-flux differential scanning calorimetry...

  6. Microstructure and mechanical properties of Sn-9Zn-xAl{sub 2}O{sub 3} nanoparticles (x=0–1) lead-free solder alloy: First-principles calculation and experimental research

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Wen-qing; Yu, Xin-ye; Li, Heng; Ma, Le; Zuo, Wei [Taiyuan University of Technology, College of Material Science and Technology, Taiyuan 030024 (China); Dong, Peng; Wang, Wen-xian [Taiyuan University of Technology, College of Material Science and Technology, Taiyuan 030024 (China); Shanxi Key Laboratory of Advanced Magnesium-based Materials, Taiyuan 030024 (China); Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); Ding, Min, E-mail: dingmin@tyut.edu.cn [Taiyuan University of Technology, College of Material Science and Technology, Taiyuan 030024 (China); Shanxi Key Laboratory of Advanced Magnesium-based Materials, Taiyuan 030024 (China); Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China)

    2016-12-15

    This paper studies microstructure and mechanical properties of Sn-9Zn-x Al{sub 2}O{sub 3} nanoparticles (x=0–1) lead-free solder alloy. The interface structure, interface energy and electronic properties of Al{sub 2}O{sub 3}/Sn9Zn interface are investigated by first-principle calculation. On the experimental part, in comparison with the plain Sn-9Zn solder, the Al{sub 2}O{sub 3} nanoparticles incorporated into the solder matrix can inhibit the growth of coarse dendrite Sn-Zn eutectic structure and refine grains of the composite solders during the solidification process of the alloys. Moreover, the microhardness and average tensile strength of the solders with addition of Al{sub 2}O{sub 3} nanoparticles increased with the increasing weight percentages of Al{sub 2}O{sub 3} nanoparticles. These improved mechanical properties can be attributed to the microstructure developments and the dispersed Al{sub 2}O{sub 3} nanoparticles.

  7. The metallurgical approach on the solder voids behaviour in surface mount devices

    International Nuclear Information System (INIS)

    Mohabattul Zaman Bukhari

    1996-01-01

    Solder voids are believed to cause poor heat dissiption in the Surface Mount devices and reduce the reliability of the devices at higher operating services. There are a lot of factors involved in creating voids such as gas/flux entrapment, wettability, outgasseous, air bubbles in the solder paste, inconsistency of solder coverage and improper metal scheme selection. This study was done to observe the behaviour of the solder voids in term of flux entrapmentt and wettability. It is believed that flux entrapment and wettability are verify this hypothesis. Two types of metal scheme were chosen which are Nickel (Ni) plated and Tin (Sn) plated heatsink. X-ray techniques such as Radiographic Inspection Analysis and EDAX were used to detect the minute solder voids. The solder voids observed on the heatsinks and Copper shims after the reflow process are believed to be a non contact voids that resulted from some portion of the surface not wetting properly

  8. Corrosive microenvironments at lead solder surfaces arising from galvanic corrosion with copper pipe.

    Science.gov (United States)

    Nguyen, Caroline K; Stone, Kendall R; Dudi, Abhijeet; Edwards, Marc A

    2010-09-15

    As stagnant water contacts copper pipe and lead solder (simulated soldered joints), a corrosion cell is formed between the metals in solder (Pb, Sn) and the copper. If the resulting galvanic current exceeds about 2 μA/cm(2), a highly corrosive microenvironment can form at the solder surface, with pH chloride concentrations at least 11 times higher than bulk water levels. Waters with relatively high chloride tend to sustain high galvanic currents, preventing passivation of the solder surface, and contributing to lead contamination of potable water supplies. The total mass of lead corroded was consistent with predictions based on the galvanic current, and lead leaching to water was correlated with galvanic current. If the concentration of sulfate in the water increased relative to chloride, galvanic currents and associated lead contamination could be greatly reduced, and solder surfaces were readily passivated.

  9. Quantitative measurement of the chemical composition of geological standards with a miniature laser ablation/ionization mass spectrometer designed for in situ application in space research

    International Nuclear Information System (INIS)

    Neuland, M B; Riedo, A; Tulej, M; Wurz, P; Grimaudo, V; Moreno-García, P; Mezger, K

    2016-01-01

    A key interest of planetary space missions is the quantitative determination of the chemical composition of the planetary surface material. The chemical composition of surface material (minerals, rocks, soils) yields fundamental information that can be used to answer key scientific questions about the formation and evolution of the planetary body in particular and the Solar System in general. We present a miniature time-of-flight type laser ablation/ionization mass spectrometer (LMS) and demonstrate its capability in measuring the elemental and mineralogical composition of planetary surface samples quantitatively by using a femtosecond laser for ablation/ionization. The small size and weight of the LMS make it a remarkable tool for in situ chemical composition measurements in space research, convenient for operation on a lander or rover exploring a planetary surface. In the laboratory, we measured the chemical composition of four geological standard reference samples USGS AGV-2 Andesite, USGS SCo-l Cody Shale, NIST 97b Flint Clay and USGS QLO-1 Quartz Latite with LMS. These standard samples are used to determine the sensitivity factors of the instrument. One important result is that all sensitivity factors are close to 1. Additionally, it is observed that the sensitivity factor of an element depends on its electron configuration, hence on the electron work function and the elemental group in agreement with existing theory. Furthermore, the conformity of the sensitivity factors is supported by mineralogical analyses of the USGS SCo-l and the NIST 97b samples. With the four different reference samples, the consistency of the calibration factors can be demonstrated, which constitutes the fundamental basis for a standard-less measurement-technique for in situ quantitative chemical composition measurements on planetary surface. (paper)

  10. Characterization of polymethyl methacrylate/polyethylene glycol/aluminum nitride composite as form-stable phase change material prepared by in situ polymerization method

    International Nuclear Information System (INIS)

    Zhang, Lei; Zhu, Jiaoqun; Zhou, Weibin; Wang, Jun; Wang, Yan

    2011-01-01

    Highlights: → Form-stable PMMA/PEG/AlN PCMs were prepared by in situ polymerization method. → AlN additive effectively enhanced the heat transfer property of composite PCMs. → The composites exhibited desirable thermal performance and electric insulativity. → The composites were available for the thermal management of electronic device. - Abstract: This work was focused on the preparation and characterization of a new type of form-stable phase change material (PCM) employed in thermal management. Using the method of in situ polymerization, polyethylene glycol (PEG) acting as the PCM and aluminum nitride (AlN) serving as the thermal conductivity promoter were uniformly encapsulated and embedded inside the three-dimensional network structure of PMMA matrix. When the mass fraction of PEG was below 70%, the prepared composite PCMs remained solid without leakage above the melting point of the PEG. XRD and FT-IR results indicated that the PEG was physically combined with PMMA matrix and AlN additive and did not participate in the polymerization. Thermal analysis results showed that the prepared composite PCMs possess available latent heat capacity and thermal stability, and the AlN additive was able to effectively enhance the heat transfer property of organic PCM. Moreover, the volume resistivity of composite achieved (5.92 ± 0.16) x 10 10 Ω cm when the mass ratio of AlN was 30%. To sum up, the prepared form-stable PCMs were competent for the thermal management of electronic device due to their acceptable thermal performance and electric insulativity.

  11. Effect of annealing on the superconducting and normal state properties of the doped multifilamentary Cu-Nb composite wires prepared by in situ technique

    International Nuclear Information System (INIS)

    Dubey, S.S.; Dheer, P.N.

    1999-01-01

    The effect of annealing on the superconducting and normal state properties of the Ga-, In-, Ti- and Zr-doped (1 wt%) Cu-Nb composite wires prepared by in situ technique have been investigated in this paper. The wires annealed at 700 C for 10 h and then quenched at room temperature, show a decrease in the superconducting transition temperature, T c , and increase in the transition width, ΔT. Doping of the Cu-Nb wires causes an increase in the normal state resistivity and hence the upper critical field, H C2 . This results in a significant increase of J c . Annealing of these doped samples decreases H C2 and J c . In the case of In- and Ga-doped samples J c shows a marginal improvement at lower field but decreases at higher field. Zr and Ti doping appears to be beneficial for the improved J c in these in situ materials. (orig.)

  12. In situ observations of meteor smoke particles (MSP during the Geminids 2010: constraints on MSP size, work function and composition

    Directory of Open Access Journals (Sweden)

    M. Rapp

    2012-12-01

    Full Text Available We present in situ observations of meteoric smoke particles (MSP obtained during three sounding rocket flights in December 2010 in the frame of the final campaign of the Norwegian-German ECOMA project (ECOMA = Existence and Charge state Of meteoric smoke particles in the Middle Atmosphere. The flights were conducted before, at the maximum activity, and after the decline of the Geminids which is one of the major meteor showers over the year. Measurements with the ECOMA particle detector yield both profiles of naturally charged particles (Faraday cup measurement as well as profiles of photoelectrons emitted by the MSPs due to their irradiation by photons of a xenon-flash lamp. The column density of negatively charged MSPs decreased steadily from flight to flight which is in agreement with a corresponding decrease of the sporadic meteor flux recorded during the same period. This implies that the sporadic meteors are a major source of MSPs while the additional influx due to the shower meteors apparently did not play any significant role. Surprisingly, the profiles of photoelectrons are only partly compatible with this observation: while the photoelectron current profiles obtained during the first and third flight of the campaign showed a qualitatively similar behaviour as the MSP charge density data, the profile from the second flight (i.e., at the peak of the Geminids shows much smaller photoelectron currents. This may tentatively be interpreted as a different MSP composition (and, hence, different photoelectric properties during this second flight, but at this stage we are not in a position to conclude that there is a cause and effect relation between the Geminids and this observation. Finally, the ECOMA particle detector used during the first and third flight employed three instead of only one xenon flash lamp where each of the three lamps used for one flight had a different window material resulting in different cut off wavelengths for these

  13. Investigation of in-situ poly(lactic acid)/soy protein concentrate composites: Composite preparation, properties and foam application development

    Science.gov (United States)

    Liu, Bo

    2011-12-01

    In this study, soy protein (SP), the residue of oil crushing, was used for preparation of value-added thermoplastics. Novel poly(lactic acid) (PLA)/soy protein concentrate (SPC) blends were investigated and foaming of the resulting blends was developed. PLA/SPC blends were prepared by twin-screw extrusion and test specimens by injection molding. Unlike the practice elsewhere SP was used as a filler in mixing with other polymers, SPC was processed as a plastic component in blending process in this work. Processing SPC as plastic component, water played an important role in terms of the deformability and the morphology of SP thus the properties of the blends. Plasticization of SP, compatibilization of the blends and structure-property relationship of the PLA/SPC blends were studied. In the literature water and glycerol were often used together in preparing SP plastics or plastic blends, but this study found that this traditional combination did not provide the best results in terms of morphology and mechanical properties. Water is only recommended in plasticizing SP in the blends. This study showed water as a plasticizer was a domain factor on control of morphology and properties of PLA/SPC blends. The due to the evaporation of water after extrusion, SP domain lost its deformability thus resulted in in-situ composites. Interconnected SPC phase structure was achieved by control water content in the pre-formulated SPC and SPC content in the blends. A novel dual compatibilization method was developed to improve the properties of PLA/SPC blends. Poly(2-ethyl-2-oxazoline) was used to improve the dispersion of SPC in the blending stage, and polymeric methylene diphenyl diisocyanate was used to improve the interfacial adhesion between SPC and PLA in the subsequent processing. The result showed excellent mechanical properties and improved thermal properties of PLA/SPC blends. Using processing aids is an effective way to decrease processing temperature and thermal degradation

  14. Effects of ZrB{sub 2} on substructure and wear properties of laser melted in situ ZrB{sub 2p}/6061Al composites

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Yida [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Chao, Yuhjin [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Luo, Zhen, E-mail: lz@tju.edu.cn [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Cai, Yangchuan [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Huang, Yongxian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China)

    2016-03-01

    Graphical abstract: - Highlights: • Laser beam partly disperses ZrB{sub 2} particle clusters and showing dispersed particles state after matrix solidification. • Laser melting process narrower cellular spacing in composites than AA6061 matrix. • Compared with matrix alloy, crystal orientation near melted layer edge of the composites is almost random duo to heterogeneous nucleation in melt and pinning effect of laser dispersed ZrB{sub 2} nanoparticles at solidification front. • Laser melted layer shows better wear properties than matrix and composite without laser melting. - Abstract: Aluminum matrix composites reinforced by in situ ZrB{sub 2} particles were successfully fabricated from an Al-KBF{sub 4}-K{sub 2}ZrF{sub 6} system via a direct melt reaction. A laser surface melting strategy is used to improve the surface strength of the in situ ZrB{sub 2p}/6061Al composite, which includes a series of laser-melted composites with different laser power processed by a 2 kW YAG laser generator. XRD and EDS results demonstrated the existence of ZrB{sub 2} nanoparticles in the composite. After laser melting, the penetration depth of the molten pool increases with increasing power density. OM and SEM analysis indicate that the laser melting process yields narrower cellular spacing of the matrix and partly disperses the ZrB{sub 2} particle clusters. Compared with laser-melted matrix alloys, the crystal orientations near the melted layers edge of the composite are almost random due to heterogeneous nucleation in the melt and the pinning effect of laser-dispersed ZrB{sub 2} nanoparticles at the solidification front. Wear test results show that the laser melted layer performs better at wear resistance than both the substrate and the matrix AA6061 by measuring wear mass loss. Compared with composite samples prepared without laser melting, the wear mass loss of the laser melted composites decreased from 61 to 56 mg under a load of 98 N for 60 min.

  15. Novel concept of recycling sludge and dust to BOF converter through dispersed in-situ phase induced by composite ball explosive reaction

    Science.gov (United States)

    Tang, Fu-ping; Yu, Shu-juan; Fei, Peng; Hou, Hou-yu; Qian, Feng; Wang, Xiao-feng

    2017-08-01

    Recycling of iron and steelmaking dusts is a key issue in environmental protection efforts and to ensure efficient utilization. In this investigation, we developed a novel recovery process that uses a dispersed in-situ phase induced by an explosive reaction of composite balls of iron and steelmaking dusts. We designed and prepared composite balls for this function using a laboratory model batch-type balling disc (at 12 r/min) and optimized the feeding modes in 180-t and 260-t basic oxygen furnace (BOF) converters. The results indicate that feeding composite balls into BOF converters is an effective novel technology for recovering iron and steelmaking dusts. The period after hot metal charging and prior to the oxygen-blowing process is the most reasonable time to feed composite balls. Composite ball treatment is not appropriate for steel production with sulfur requirements lower than 80 ppm. The maximum composite ball feeding amount is 40 kg/t and the iron yield rate is better than 95%. Compared with the conventional recycling process of sludge and dust, this novel technology is more convenient and efficient, saving up to 309 RMB per ton of steel. Further investigation of this novel recycling technology is merited.

  16. Laser tissue welding mediated with a protein solder

    Science.gov (United States)

    Small, Ward, IV; Heredia, Nicholas J.; Celliers, Peter M.; Da Silva, Luiz B.; Eder, David C.; Glinsky, Michael E.; London, Richard A.; Maitland, Duncan J.; Matthews, Dennis L.; Soltz, Barbara A.

    1996-05-01

    A study of laser tissue welding mediated with an indocyanine green dye-enhanced protein solder was performed. Freshly obtained sections of porcine artery were used for the experiments. Sample arterial wall thickness ranged from two to three millimeters. Incisions approximately four millimeters in length were treated using an 805 nanometer continuous- wave diode laser coupled to a one millimeter diameter fiber. Controlled parameters included the power delivered by the laser, the duration of the welding process, and the concentration of dye in the solder. A two-color infrared detection system was constructed to monitor the surface temperatures achieved at the weld site. Burst pressure measurements were made to quantify the strengths of the welds immediately following completion of the welding procedure.

  17. Development of an in-situ multi-component reinforced Al-based metal matrix composite by direct metal laser sintering technique — Optimization of process parameters

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Subrata Kumar, E-mail: subratagh82@gmail.com [Department of Mechanical Engineering, National Institute of Technology Agartala, Tripura 799055 (India); Bandyopadhyay, Kaushik; Saha, Partha [Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2014-07-01

    In the present investigation, an in-situ multi-component reinforced aluminum based metal matrix composite was fabricated by the combination of self-propagating high-temperature synthesis and direct metal laser sintering process. The different mixtures of Al, TiO{sub 2} and B{sub 4}C powders were used to initiate and maintain the self-propagating high-temperature synthesis by laser during the sintering process. It was found from the X-ray diffraction analysis and scanning electron microscopy that the reinforcements like Al{sub 2}O{sub 3}, TiC, and TiB{sub 2} were formed in the composite. The scanning electron microscopy revealed the distribution of the reinforcement phases in the composite and phase identities. The variable parameters such as powder layer thickness, laser power, scanning speed, hatching distance and composition of the powder mixture were optimized for higher density, lower porosity and higher microhardness using Taguchi method. Experimental investigation shows that the density of the specimen mainly depends upon the hatching distance, composition and layer thickness. On the other hand, hatching distance, layer thickness and laser power are the significant parameters which influence the porosity. The composition, laser power and layer thickness are the key influencing parameters for microhardness. - Highlights: • The reinforcements such as Al{sub 2}O{sub 3}, TiC, and TiB{sub 2} were produced in Al-MMC through SHS. • The density is mainly influenced by the material composition and hatching distance. • Hatching distance is the major influencing parameter on porosity. • The material composition is the significant parameter to enhance the microhardness. • The SEM micrographs reveal the distribution of TiC, TiB{sub 2} and Al{sub 2}O{sub 3} in the composite.

  18. Development of an in-situ multi-component reinforced Al-based metal matrix composite by direct metal laser sintering technique — Optimization of process parameters

    International Nuclear Information System (INIS)

    Ghosh, Subrata Kumar; Bandyopadhyay, Kaushik; Saha, Partha

    2014-01-01

    In the present investigation, an in-situ multi-component reinforced aluminum based metal matrix composite was fabricated by the combination of self-propagating high-temperature synthesis and direct metal laser sintering process. The different mixtures of Al, TiO 2 and B 4 C powders were used to initiate and maintain the self-propagating high-temperature synthesis by laser during the sintering process. It was found from the X-ray diffraction analysis and scanning electron microscopy that the reinforcements like Al 2 O 3 , TiC, and TiB 2 were formed in the composite. The scanning electron microscopy revealed the distribution of the reinforcement phases in the composite and phase identities. The variable parameters such as powder layer thickness, laser power, scanning speed, hatching distance and composition of the powder mixture were optimized for higher density, lower porosity and higher microhardness using Taguchi method. Experimental investigation shows that the density of the specimen mainly depends upon the hatching distance, composition and layer thickness. On the other hand, hatching distance, layer thickness and laser power are the significant parameters which influence the porosity. The composition, laser power and layer thickness are the key influencing parameters for microhardness. - Highlights: • The reinforcements such as Al 2 O 3 , TiC, and TiB 2 were produced in Al-MMC through SHS. • The density is mainly influenced by the material composition and hatching distance. • Hatching distance is the major influencing parameter on porosity. • The material composition is the significant parameter to enhance the microhardness. • The SEM micrographs reveal the distribution of TiC, TiB 2 and Al 2 O 3 in the composite

  19. Effect of Mo on Microstructures and Wear Properties of In Situ Synthesized Ti(C,N)/Ni-Based Composite Coatings by Laser Cladding.

    Science.gov (United States)

    Wu, Fan; Chen, Tao; Wang, Haojun; Liu, Defu

    2017-09-06

    Using Ni60 alloy, C, TiN and Mo mixed powders as the precursor materials, in situ synthesized Ti(C,N) particles reinforcing Ni-based composite coatings are produced on Ti6Al4V alloys by laser cladding. Phase constituents, microstructures and wear properties of the composite coatings with 0 wt % Mo, 4 wt % Mo and 8 wt % Mo additions are studied comparatively. Results indicate that Ti(C,N) is formed by the in situ metallurgical reaction, the (Ti,Mo)(C,N) rim phase surrounding the Ti(C,N) ceramic particle is synthesized with the addition of Mo, and the increase of Mo content is beneficial to improve the wear properties of the cladding coatings. Because of the effect of Mo, the grains are remarkably refined and a unique core-rim structure that is uniformly dispersed in the matrix appears; meanwhile, the composite coatings with Mo addition exhibit high hardness and excellent wear resistance due to the comprehensive action of dispersion strengthening, fine grain strengthening and solid solution strengthening.

  20. Controlling the Sn-C bonds content in SnO2@CNTs composite to form in situ pulverized structure for enhanced electrochemical kinetics.

    Science.gov (United States)

    Cheng, Yayi; Huang, Jianfeng; Qi, Hui; Cao, Liyun; Luo, Xiaomin; Li, Jiayin; Xu, Zhanwei; Yang, Jun

    2017-12-07

    The Sn-C bonding content between the SnO 2 and CNTs interface was controlled by the hydrothermal method and subsequent heat treatment. Electrochemical analysis found that the SnO 2 @CNTs with high Sn-C bonding content exhibited much higher capacity contribution from alloying and conversion reaction compared with the low content of Sn-C bonding even after 200 cycles. The high Sn-C bonding content enabled the SnO 2 nanoparticles to stabilize on the CNTs surface, realizing an in situ pulverization process of SnO 2 . The in situ pulverized structure was beneficial to maintain the close electrochemical contact of the working electrode during the long-term cycling and provide ultrafast transfer paths for lithium ions and electrons, which promoted the alloying and conversion reaction kinetics greatly. Therefore, the SnO 2 @CNTs composite with high Sn-C bonding content displayed highly reversible alloying and conversion reaction. It is believed that the composite could be used as a reference for design chemically bonded metal oxide/carbon composite anode materials in lithium-ion batteries.

  1. Quality Analysis of Welded and Soldered Joints of Cu-Nb Microcomposite Wires

    Directory of Open Access Journals (Sweden)

    Nikolaj VIŠNIAKOV

    2011-03-01

    Full Text Available Quality analysis of welded and soldered joints of Cu-Nb microcomposite wires has been performed. Quality and mechanical characteristics of joints as ultimate tensile stress limit and elongation at break were measured with an universal testing machine and controlled visually using an optical microscope. Two wires joints were soldered with silver and copper solders and put into steel and copper sleeve respectively. Another two wires joints were soldered with silver solder and welded without any reinforcement. Joints soldered with the silver solder and steel sleeve have demonstrated the best mechanical characteristics: ultimate tensile stress limit of 650 MPa and elongation at break of 0.85 %. Joints soldered with the copper sleeve have no advantages comparing with the soldered butt joint. Ultimate tensile stress limit and elongation at break were in 300 MPa - 350 MPa and in 0.35 % - 0.45 % ranges respectively. Two welded joints had ultimate tensile stress limit of 470 MPa and elongation at break of 0.71 %. In all joints the microstructure of Nb filaments was destroyed and mechanical properties have been specified by mechanical strength of copper and sleeve materials only.http://dx.doi.org/10.5755/j01.ms.17.1.242

  2. Reliability of soldered joints for automotive electronic devices; Denso buhin ni okeru handa setsugo no shinraisei

    Energy Technology Data Exchange (ETDEWEB)

    Kita, T; Mukaibo, N; Ando, K; Moriyama, M [Honda R and D Co. Ltd., Tokyo (Japan)

    1997-10-01

    Concerning the tin and lead eutectic solder, we have evaluated the reliability of three factors of intermetallic compound layer, creep and vibration which cause solder degradation. First, the stress factor was extracted from investigating the mechanism of degradation, and the best acceleration test method was fixed. Next, the acceleration test was executed to find the stress dependency and the tendency of solder degradation was modeled numerically. While the environmental stress frequency was obtained and they were put together by using a minor method, which enabled us to predict the life span of solder on the market with precision. 5 refs., 13 figs.

  3. Influence of Difference Solders Volume on Intermetallic Growth of Sn-4.0Ag-0.5Cu/ENEPIG

    Directory of Open Access Journals (Sweden)

    Saliza Azlina O.

    2016-01-01

    Full Text Available In recent years, portable electronic packaging products such as smart phones, tablets, notebooks and other gadgets have been developed with reduced size of component packaging, light weight, high speed and with enhanced performance. Thus, flip chip technology with smaller solder sphere sizes that would produce fine solder joint interconnections have become essential in order to fulfill these miniaturization requirements. This study investigates the interfacial reactions and intermetallics formation during reflow soldering and isothermal aging between Sn-4.0Ag-0.5Cu (SAC405 and electroless nickel/immersion palladium/immersion gold (EN(PEPIG. Solder diameters of 300 μm and 700 μm were used to compare the effect of solder volume on the solder joint microstructure. The solid state isothermal aging was performed at 125°C starting from 250 hours until 2000 hours. The results revealed that only (Cu,Ni6Sn5 IMC was found at the interface during reflow soldering while both (Cu,Ni6Sn5 and (Ni,Cu3Sn4 IMC have been observed after aging process. Smaller solder sizes produced thinner IMC than larger solder joints investigated after reflow soldering, whereas the larger solders produced thinner IMC than the smaller solders after isothermal aging. Aging duration of solder joints has been found to be increase the IMC’s thickness and changed the IMC morphologies to spherical-shaped, compacted and larger grain size.

  4. Laser beam soldering of micro-optical components

    Science.gov (United States)

    Eberhardt, R.

    2003-05-01

    MOTIVATION Ongoing miniaturisation and higher requirements within optical assemblies and the processing of temperature sensitive components demands for innovative selective joining techniques. So far adhesive bonding has primarily been used to assemble and adjust hybrid micro optical systems. However, the properties of the organic polymers used for the adhesives limit the application of these systems. In fields of telecommunication and lithography, an enhancement of existing joining techniques is necessary to improve properties like humidity resistance, laserstability, UV-stability, thermal cycle reliability and life time reliability. Against this background laser beam soldering of optical components is a reasonable joining technology alternative. Properties like: - time and area restricted energy input - energy input can be controlled by the process temperature - direct and indirect heating of the components is possible - no mechanical contact between joining tool and components give good conditions to meet the requirements on a joining technology for sensitive optical components. Additionally to the laser soldering head, for the assembly of optical components it is necessary to include positioning units to adjust the position of the components with high accuracy before joining. Furthermore, suitable measurement methods to characterize the soldered assemblies (for instance in terms of position tolerances) need to be developed.

  5. Scalable Manufacturing of Solderable and Stretchable Physiologic Sensing Systems.

    Science.gov (United States)

    Kim, Yun-Soung; Lu, Jesse; Shih, Benjamin; Gharibans, Armen; Zou, Zhanan; Matsuno, Kristen; Aguilera, Roman; Han, Yoonjae; Meek, Ann; Xiao, Jianliang; Tolley, Michael T; Coleman, Todd P

    2017-10-01

    Methods for microfabrication of solderable and stretchable sensing systems (S4s) and a scaled production of adhesive-integrated active S4s for health monitoring are presented. S4s' excellent solderability is achieved by the sputter-deposited nickel-vanadium and gold pad metal layers and copper interconnection. The donor substrate, which is modified with "PI islands" to become selectively adhesive for the S4s, allows the heterogeneous devices to be integrated with large-area adhesives for packaging. The feasibility for S4-based health monitoring is demonstrated by developing an S4 integrated with a strain gauge and an onboard optical indication circuit. Owing to S4s' compatibility with the standard printed circuit board assembly processes, a variety of commercially available surface mount chip components, such as the wafer level chip scale packages, chip resistors, and light-emitting diodes, can be reflow-soldered onto S4s without modifications, demonstrating the versatile and modular nature of S4s. Tegaderm-integrated S4 respiration sensors are tested for robustness for cyclic deformation, maximum stretchability, durability, and biocompatibility for multiday wear time. The results of the tests and demonstration of the respiration sensing indicate that the adhesive-integrated S4s can provide end users a way for unobtrusive health monitoring. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Processing map and hot working mechanisms in a P/M TiAl alloy composite with in situ carbide and silicide dispersions

    International Nuclear Information System (INIS)

    Rao, K.P.; Prasad, Y.V.R.K.

    2010-01-01

    Research highlights: Mechanical alloying of Ti and Al with small additions of Si and C was used to synthesize metastable phases, which were incorporated in Ti-Al matrices using powder metallurgy techniques. These metastable phases (or also called as precursors), at higher temperatures, transformed in situ into very fine hard reinforcements that develop coherent interface with the surrounding matrix. Typically, Ti5Si3 and TiC are the end products after the synthesis of composite. In this study, hot working behavior of such composites has been studied using the concepts of processing maps to identify the safe and best processing conditions that should be adopted while forming this composite. Also, kinetic analysis of hot deformation has been performed to identify the dominant deformation mechanism. The results are compared with that of base TiAl matrix. The powder metallurgy route offers the advantage of working the material at much lower temperatures compared to the traditional cast and forge route. - Abstract: A titanium aluminide alloy composite with in situ carbide and silicide dispersions has been synthesized by mixing 90% of matrix with elemental composition of 46Ti-46Al-4Nb-2Cr-2Mn and 10% precursor with composition 55Ti-27Al-12Si-6C prepared by mechanical alloying. The powder mixture was blended for 2 h followed by hot isostatic pressing (HIP) at 1150 deg. C for 4 h under a pressure of 150 MPa. In addition to TiAl alloy matrix, the microstructure of the HIP'ed billet showed a small volume fraction of Nb-rich intermetallic phase along with carbide and silicide dispersions formed in situ during HIP'ing. Cylindrical specimens from the HIP'ed billets were compressed at temperatures and strain rates in the ranges of 800-1050 deg. C and 0.0001-1 s -1 . The flow curves exhibited flow softening leading to a steady-state flow at strain rates lower than 0.01 s -1 while fracture occurred at higher strain rates. The processing map developed on the basis of flow stress at

  7. Microstructure and wear of in-situ Ti/(TiN + TiB) hybrid composite layers produced using liquid phase process

    Energy Technology Data Exchange (ETDEWEB)

    Yazdi, R., E-mail: ryazdi@ut.ac.ir; Kashani-Bozorg, S.F.

    2015-02-15

    Tungsten inert gas (TIG) technique was conducted on commercially pure (CP)-Ti substrate, which was coated with h-BN-based powder mixture prior to the treatment. The treated surfaces were evaluated and characterized by means of scanning electron microscope (SEM), X-ray diffraction analysis, and electron dispersive spectrometry (EDS). The microhardness and wear experiment were also performed by using a microhardness machine and pin-on-disk tribometer. As h-BN reacted with titanium, an in-situ hybrid composite layer was formed showing near stoichiometric dendrites of TiN, platelets of TiB and interdendritic regions of α′-Ti martensite crystal structures. The population level of TiN and TiB regions were found to increase using a pre-placed powder mixture with greater h-BN content. However, the fabricated layers exhibited cracking and porosity; these were minimized by adjusting arc energy density and h-BN content of powder mixture. The microhardness value of the fabricated hybrid composite layers was found to be in the range of ∼650 HV{sub 0.2}–1000 HV{sub 0.2}; this is three to five times higher than that of the untreated CP-Ti substrate. In addition, the in-situ hybrid composite layers exhibited superior wear behavior over CP-Ti substrate; this is attributed to the formation of newly formed ceramic phases in the solidified surface layers and good coherent interface between the composite layer and CP-substrate. Meanwhile, severe adhesive wear mechanism of CP-titanium surface changed to mild abrasive one as a result of surface treatment. - Highlights: • In-situ Ti/(TiN + TiB) hybrid composite layers were synthesized by TIG processing on commercially pure titanium. • The microstructure features were characterized by several methods. • Microhardness enhanced three to five times higher than that of the CP-Ti substrate after surface modification. • The fabricated composite layers improved wear resistance of CP-titanium. • Severe adhesive wear mechanism of

  8. Development of routines for simultaneous in situ chemical composition and stable Si isotope ratio analysis by femtosecond laser ablation inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Frick, Daniel A., E-mail: dfrick@gfz-potsdam.de [GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany); Schuessler, Jan A. [GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany); Blanckenburg, Friedhelm von [GFZ German Research Centre for Geosciences, 14473 Potsdam (Germany); Institute of Geological Science, Freie Universität Berlin, 12249 Berlin (Germany)

    2016-09-28

    Stable metal (e.g. Li, Mg, Ca, Fe, Cu, Zn, and Mo) and metalloid (B, Si, Ge) isotope ratio systems have emerged as geochemical tracers to fingerprint distinct physicochemical reactions. These systems are relevant to many Earth Science questions. The benefit of in situ microscale analysis using laser ablation (LA) over bulk sample analysis is to use the spatial context of different phases in the solid sample to disclose the processes that govern their chemical and isotopic compositions. However, there is a lack of in situ analytical routines to obtain a samples' stable isotope ratio together with its chemical composition. Here, we evaluate two novel analytical routines for the simultaneous determination of the chemical and Si stable isotope composition (δ{sup 30}Si) on the micrometre scale in geological samples. In both routines, multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is combined with femtosecond-LA, where stable isotope ratios are corrected for mass bias using standard-sample-bracketing with matrix-independent calibration. The first method is based on laser ablation split stream (LASS), where the laser aerosol is split and introduced simultaneously into both the MC-ICP-MS and a quadrupole ICP-MS. The second method is based on optical emission spectroscopy using direct observation of the MC-ICP-MS plasma (LA-MC-ICP-MS|OES). Both methods are evaluated using international geological reference materials. Accurate and precise Si isotope ratios were obtained with an uncertainty typically better than 0.23‰, 2SD, δ{sup 30}Si. With both methods major element concentrations (e.g., Na, Al, Si, Mg, Ca) can be simultaneously determined. However, LASS-ICP-MS is superior over LA-MC-ICP-MS|OES, which is limited by its lower sensitivity. Moreover, LASS-ICP-MS offers trace element analysis down to the μg g{sup −1}-range for more than 28 elements due to lower limits of detection, and with typical uncertainties better than 15%. For in situ

  9. Development of routines for simultaneous in situ chemical composition and stable Si isotope ratio analysis by femtosecond laser ablation inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Frick, Daniel A.; Schuessler, Jan A.; Blanckenburg, Friedhelm von

    2016-01-01

    Stable metal (e.g. Li, Mg, Ca, Fe, Cu, Zn, and Mo) and metalloid (B, Si, Ge) isotope ratio systems have emerged as geochemical tracers to fingerprint distinct physicochemical reactions. These systems are relevant to many Earth Science questions. The benefit of in situ microscale analysis using laser ablation (LA) over bulk sample analysis is to use the spatial context of different phases in the solid sample to disclose the processes that govern their chemical and isotopic compositions. However, there is a lack of in situ analytical routines to obtain a samples' stable isotope ratio together with its chemical composition. Here, we evaluate two novel analytical routines for the simultaneous determination of the chemical and Si stable isotope composition (δ 30 Si) on the micrometre scale in geological samples. In both routines, multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is combined with femtosecond-LA, where stable isotope ratios are corrected for mass bias using standard-sample-bracketing with matrix-independent calibration. The first method is based on laser ablation split stream (LASS), where the laser aerosol is split and introduced simultaneously into both the MC-ICP-MS and a quadrupole ICP-MS. The second method is based on optical emission spectroscopy using direct observation of the MC-ICP-MS plasma (LA-MC-ICP-MS|OES). Both methods are evaluated using international geological reference materials. Accurate and precise Si isotope ratios were obtained with an uncertainty typically better than 0.23‰, 2SD, δ 30 Si. With both methods major element concentrations (e.g., Na, Al, Si, Mg, Ca) can be simultaneously determined. However, LASS-ICP-MS is superior over LA-MC-ICP-MS|OES, which is limited by its lower sensitivity. Moreover, LASS-ICP-MS offers trace element analysis down to the μg g −1 -range for more than 28 elements due to lower limits of detection, and with typical uncertainties better than 15%. For in situ

  10. The chemical composition and mineralogy of meteorites measured with very high spatial resolution by a laser mass spectrometer for in situ planetary research

    Science.gov (United States)

    Brigitte Neuland, Maike; Mezger, Klaus; Tulej, Marek; Frey, Samira; Riedo, Andreas; Wurz, Peter; Wiesendanger, Reto

    2017-04-01

    The knowledge of the chemical composition of moons, comets, asteroids or other planetary bodies is of particular importance for the investigation of the origin and evolution of the Solar System. High resolution in situ studies on planetary surfaces can yield important information on surface heterogeneity, basic grain mineralogy and chemical composition of surface and subsurface. In turn, these data are the basis for our understanding of the physical and chemical processes which led to the formation and alteration of planetary material [1]. We investigated samples of Allende and Sayh al Uhaymir with a highly miniaturised laser mass spectrometer (LMS), which has been designed and built for in situ space research [2,3]. Both meteorite samples were investigated with a spatial resolution of about 10μm in lateral direction. The high sensitivity and high dynamic range of the LMS allow for quantitative measurements of the abundances of the rock-forming and minor and trace elements with high accuracy [4]. From the data, the modal mineralogy of micrometre-sized chondrules can be inferred [5], conclusions about the condensation sequence of the material are possible and the sensitivity for radiogenic elements allows for dating analyses of the investigated material. We measured the composition of various chondrules in Allende, offering valuable clues about the condensation sequence of the different components of the meteorite. We explicitly investigated the chemical composition and heterogeneity of the Allende matrix with an accuracy that cannot be reached by the mechanical analysis methods that were and are widely used in meteoritic research. We demonstrate the capabilities for dating analyses with the LMS. By applying the U-Th-dating method, the age of the SaU169 sample could be determined. Our analyses show that the LMS would be a suitable instrument for high-quality quantitative chemical composition measurements on the surface of a celestial body like a planet, moon or

  11. Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part I. Microstructural Characterization of Rapidly Solidified Solders

    Science.gov (United States)

    Reeve, Kathlene N.; Choquette, Stephanie M.; Anderson, Iver E.; Handwerker, Carol A.

    2016-12-01

    Particles of Cu x Al y in Sn-Cu-Al solders have previously been shown to nucleate the Cu6Sn5 phase during solidification. In this study, the number and size of Cu6Sn5 nucleation sites were controlled through the particle size refinement of Cu x Al y via rapid solidification processing and controlled cooling in a differential scanning calorimeter. Cooling rates spanning eight orders of magnitude were used to refine the average Cu x Al y and Cu6Sn5 particle sizes down to submicron ranges. The average particle sizes, particle size distributions, and morphologies in the microstructures were analyzed as a function of alloy composition and cooling rate. Deep etching of the samples revealed the three-dimensional microstructures and illuminated the epitaxial and morphological relationships between the Cu x Al y and Cu6Sn5 phases. Transitions in the Cu6Sn5 particle morphologies from faceted rods to nonfaceted, equiaxed particles were observed as a function of both cooling rate and composition. Initial solidification cooling rates within the range of 103 to 104 °C/s were found to be optimal for realizing particle size refinement and maintaining the Cu x Al y /Cu6Sn5 nucleant relationship. In addition, little evidence of the formation or decomposition of the ternary- β phase in the solidified alloys was noted. Solidification pathways omitting the formation of the ternary- β phase agreed well with observed room temperature microstructures.

  12. Centrifugally cast Zn-27Al-xMg-ySi alloys and their in situ (Mg2Si + Si)/ZA27 composites

    International Nuclear Information System (INIS)

    Wang Qudong; Chen Yongjun; Chen Wenzhou; Wei Yinhong; Zhai Chunquan; Ding Wenjiang

    2005-01-01

    Effects of composition, mold temperature, rotating rate and modification on microstructure of centrifugally cast Zn-27Al-xMg-ySi alloys have been investigated. In situ composites of Zn-27Al-6.3Mg-3.7Si and Zn-27Al-9.8Mg-5.2Si alloys were fabricated by centrifugal casting using heated permanent mold. These composites consist of three layers: inner layer segregates lots of blocky primary Mg 2 Si and a litter blocky primary Si, middle layer contains without primary Mg 2 Si and primary Si, outer layer contains primary Mg 2 Si and primary Si. The position, quantity and distribution of primary Mg 2 Si and primary Si in the composites are determined jointly by alloy composition, solidification velocity under the effect of centrifugal force and their floating velocity inward. Na salt modifier can refine grain and primary Mg 2 Si and make primary Mg 2 Si distribute more evenly and make primary Si nodular. For centrifugally cast Zn-27Al-3.2Mg-1.8Si alloy, the microstructures of inner layer, middle layer and outer layer are almost similar, single layer materials without primary Mg 2 Si and primary Si are obtained, and their grain sizes increased with the mold temperature increasing

  13. In situ polymerization and characterization of grafted poly (3,4-ethylenedioxythiophene)/multiwalled carbon nanotubes composite with high electrochemical performances

    International Nuclear Information System (INIS)

    Bai, Xiaoxia; Hu, Xiujie; Zhou, Shuyun; Yan, Jun; Sun, Chenghua; Chen, Ping; Li, Laifeng

    2013-01-01

    Graphical abstract: The homogeneously grafted PEDOT/MWCNTs containing numerous whorl fingerprint-like open ends endows with excellent electrochemical performances. Highlights: ► A ternary phase system with the surfactant AOT is utilized to efficiently solve the problem of the aggregation of MWCNTs. ► The homogenously grafted PEDOT/MWCNTs composite is synthesized by in situ chemical polymerization in the ternary phase system. ► The core–shell nanotubes contain many whorl fingerprint-like open ends that are greatly favorable for the transportation of the electrons and ions. ► The energy density of grafted PEDOT/MWCNTs has been enhanced by a factor of four comparing to that of native MWCNTs. ► The grafted PEDOT/MWCNTs composite manifests better cycle durability than both the constituents. - Abstract: The homogenously grafted composite of poly (3,4-ethylenedioxythiophene)/multiwalled carbon nanotubes (PEDOT/MWCNTs) is synthesized by in situ chemical polymerization in a ternary phase system. When carbon nanotubes are dispersed in this system containing sodium bis(2-ethylhexyl) sulfosuccinate (AOT), the surfactant AOT can efficiently hinter the aggregation of MWCNTs by absorbing and arranging regularly on the MWCNT surface. It is greatly advantageous to the stabilization of MWCNTs, which leads to the equally grafted composite. Its morphology was observed by scanning and transmission electron microscopes. Especially, the core–shell nanotubes contain many whorl fingerprint-like open ends that are efficiently favorable for the transportation of the electrons and ions. Such grafted PEDOT/MWCNTs composite nanotubes manifest enhanced electrochemical performances. We investigate the application of PEDOT/MWCNTs as a high-property supercapacitor and test its capacitive performance by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The energy density of grafted composite, 11.3 Wh kg −1 , has been enhanced by a factor

  14. Polymethyl methacrylate and polystyrene with layered double hydroxide nano composites: In situ synthesis, morphology and thermal properties; Nanocompositos de polimetacrilato de metila e poliestireno com hidroxido duplo lamelar: sintese in situ, morfologia e propriedades termicas

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Over the past decade, polymer nanocomposites have attracted interest, both in industry and in academia, because they often exhibit remarkable improvement in their properties when compared with pure polymer or conventional micro and macro-composites using low levels of reinforcements. In this work polymethyl methacrylate and polystyrene reinforced with layered double hydroxide, which was intercalated with sodium dodecyl sulfate were synthesized by in situ bulk polymerization. The nanocomposites were characterized and compared by X-ray diffraction, thermogravimetric analysis and flammability test. The X-ray diffraction demonstrated that synthesized nanocomposites showed a high global dispersion of layered double hydroxide, suggesting exfoliated morphology. The result of thermogravimetric analysis and flammability test for synthesized polystyrene/ layered double hydroxide nanocomposite presented a significant improvement in thermal stability and flammability property when compared with pure polymer. (author)

  15. Damage behavior of SnAgCu/Cu solder joints subjected to thermomechanical cycling

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, H., E-mail: xiaohui2013@yahoo.com.cn; Li, X.Y.; Hu, Y.; Guo, F.; Shi, Y.W.

    2013-11-25

    Highlights: •A creep–fatigue damage model based on CDM was proposed. •Designed system includes load frame, strain measure device and damage test device. •Damage evolution of solder joints was a function of accumulated inelastic strain. •Damage of solder joints is an interaction between creep and low-cycle fatigue. -- Abstract: Thermomechanical fatigue damage is a progressive process of material degradation. The objective of this study was to investigate the damage behavior of SnAgCu/Cu solder joints under thermomechanical cycling. A damage model was proposed based on continuum damage mechanics (CDM). Based upon an analysis of displacements for flip-chip solder joints subjected to thermal cycling, a special bimetallic loading frame with single-solder joint samples was designed to simulate the service conditions of actual joints in electronic packages. The assembly, which allowed for strain measurements of an individual solder joint during temperature cycling, was used to investigate the impact of stress–strain cycling on the damage behavior of SnAgCu/Cu solder joints. The characteristic parameters of the damage model were determined through thermomechanical cycling and strain measurement tests. The damage variable D = 1 − R{sub 0}/R was selected, and values for it were obtained using a four-probe method for the single-solder joint samples every dozen cycles during thermomechanical cycling tests to verify the model. The results showed that the predicted damage was in good agreement with the experimental results. The damage evolution law proposed here is a function of inelastic strain, and the results showed that the damage rate of SnAgCu/Cu solder joints increased as the range of the applied strain increased. In addition, the microstructure evolution of the solder joints was analyzed using scanning electron microscopy, which provided the microscopic explanation for the damage evolution law of SnAgCu/Cu solder joints.

  16. Damage behavior of SnAgCu/Cu solder joints subjected to thermomechanical cycling

    International Nuclear Information System (INIS)

    Xiao, H.; Li, X.Y.; Hu, Y.; Guo, F.; Shi, Y.W.

    2013-01-01

    Highlights: •A creep–fatigue damage model based on CDM was proposed. •Designed system includes load frame, strain measure device and damage test device. •Damage evolution of solder joints was a function of accumulated inelastic strain. •Damage of solder joints is an interaction between creep and low-cycle fatigue. -- Abstract: Thermomechanical fatigue damage is a progressive process of material degradation. The objective of this study was to investigate the damage behavior of SnAgCu/Cu solder joints under thermomechanical cycling. A damage model was proposed based on continuum damage mechanics (CDM). Based upon an analysis of displacements for flip-chip solder joints subjected to thermal cycling, a special bimetallic loading frame with single-solder joint samples was designed to simulate the service conditions of actual joints in electronic packages. The assembly, which allowed for strain measurements of an individual solder joint during temperature cycling, was used to investigate the impact of stress–strain cycling on the damage behavior of SnAgCu/Cu solder joints. The characteristic parameters of the damage model were determined through thermomechanical cycling and strain measurement tests. The damage variable D = 1 − R 0 /R was selected, and values for it were obtained using a four-probe method for the single-solder joint samples every dozen cycles during thermomechanical cycling tests to verify the model. The results showed that the predicted damage was in good agreement with the experimental results. The damage evolution law proposed here is a function of inelastic strain, and the results showed that the damage rate of SnAgCu/Cu solder joints increased as the range of the applied strain increased. In addition, the microstructure evolution of the solder joints was analyzed using scanning electron microscopy, which provided the microscopic explanation for the damage evolution law of SnAgCu/Cu solder joints

  17. Investigation of creep threshold stresses using in situ TEM straining experiment in an Al-5Y2O3-10SiC composite

    International Nuclear Information System (INIS)

    Deshmukh, S.P.; Mishra, R.S.; Robertson, I.M.

    2010-01-01

    Creep behavior of metal matrix composites is similar to dispersion strengthen alloys and characterized by the presence of a threshold stress below which the creep rate is negligible. This threshold stress is attributed, at least in dispersion-strengthened alloys, to dislocation particle interactions in which the detachment of the dislocations from the particle is the rate-limiting step. Creep experiments were performed on an Al-5Y 2 O 3 -10SiC composite in the temperature range of 473 and 573 K and the nature of the dislocation-particle interaction was determined by performing in situ straining experiments at elevated temperature in a transmission electron microscope. The threshold stress and the detachment stress are temperature dependent and the detachment stress is less than the threshold stress emphasizing the contribution of load transfer from the matrix to the reinforcement phase.

  18. Effect of in-situ TiC particulate on the wear resistance of spray-deposited 7075 Al matrix composite

    International Nuclear Information System (INIS)

    Wang Feng; Liu Huimin; Yang Bin

    2005-01-01

    TiC reinforced 7075 Al matrix composites have been fabricated by a melt in-situ reaction spray deposition. The microstructures of spray-deposited alloys were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The dry sliding wear behavior of the alloys was investigated using a pin-on-disc machine under four loads, namely 8.9, 17.8, 26.7 and 35.6 N. It has been found that the wear behavior of the alloys was dependent on the TiC content in the microstructure and the applied load. At a lower load (8.9 N), with increasing TiC content, the wear rate of the alloy was decreased. At a higher loads (26.7, 35.6 N), a spray-deposited 7075 Al alloy exhibited superior wear resistance to the 7075/TiC composites

  19. New In Situ Synthesis Method for Fe3O4/Flake Graphite Nanosheet Composite Structure and Its Application in Anode Materials of Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Chenhao Qian

    2018-01-01

    Full Text Available High-pressure torsion (HPT, a severe plastic deformation (SPD method, is rarely used in the manufacturing process of functional materials. In the present work, the authors creatively proposed using HPT as an alternative method an approach for high energy ball-milling in the preparation of an Fe3O4 and lamellar graphite nanosheet (GNS composite material. The corresponding electrochemical experiments verified that the in situ synthesized Fe3O4/GNS composite material has good lithium-storage performance and that it can retain good capacity (548.2 mA h g−1 even after several hundred cycles with high current density (8 C. Meanwhile, this performance has directly confirmed that SPD technique has great potential for the preparation of anode materials of lithium-ion batteries, especially in manufacturing metallic functional nanomaterials.

  20. X-ray tomography studies on porosity and particle size distribution in cast in-situ Al-Cu-TiB{sub 2} semi-solid forged composites

    Energy Technology Data Exchange (ETDEWEB)

    Mathew, James; Mandal, Animesh [School of Minerals, Metallurgical and Materials Engineering, Indian Institute of Technology, Bhubaneswar (India); Warnett, Jason; Williams, Mark A. [WMG, University of Warwick, Coventry CV4 7AL (United Kingdom); Chakraborty, Madhusudan [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur (India); Srirangam, Prakash, E-mail: p.srirangam@warwick.ac.uk [WMG, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2016-08-15

    X-ray computed tomography (XCT) was used to characterise the internal microstructure and clustering behaviour of TiB{sub 2} particles in in-situ processed Al-Cu metal matrix composites prepared by casting method. Forging was used in semi-solid state to reduce the porosity and to uniformly disperse TiB{sub 2} particles in the composite. Quantification of porosity and clustering of TiB{sub 2} particles was evaluated for different forging reductions (30% and 50% reductions) and compared with an as-cast sample using XCT. Results show that the porosity content was decreased by about 40% due to semi-solid forging as compared to the as-cast condition. Further, XCT results show that the 30% forging reduction resulted in greater uniformity in distribution of TiB{sub 2} particles within the composite compared to as-cast and the 50% forge reduction in semi-solid state. These results show that the application of forging in semi-solid state enhances particle distribution and reduces porosity formation in cast in-situ Al-Cu-TiB{sub 2} metal matrix composites. - Highlights: •XCT was used to visualise 3D internal structure of Al-Cu-TiB{sub 2} MMCs. •Al-Cu-TiB{sub 2} MMC was prepared by casting using flux assisted synthesis method. •TiB{sub 2} particles and porosity size distribution were evaluated. •Results show that forging in semi-solid condition decreases the porosity content and improve the particle dispersion in MMCs.

  1. Beta-Tin Grain Formation in Aluminum-Modified Lead-Free Solder Alloys

    Science.gov (United States)

    Reeve, Kathlene N.; Handwerker, Carol A.

    2018-01-01

    The limited number of independent β-Sn grain orientations that typically form during solidification of Sn-based solders and the resulting large β-Sn grain size have major effects on overall solder performance and reliability. This study analyzes whether additions of Al to Sn-Cu and Sn-Cu-Ag alloys can be used to change the grain size, morphology, and twinning structures of atomized (as-solidified) and re-melted (reflowed) β-Sn dendrites as determined using scanning electron microscopy and electron backscatter diffraction for as-solidified and reflow cycled (20-250°C, 1-5 cycles) Sn-Cu-Al and Sn-Ag-Cu-Al drip atomized spheres (260 μm diameter). The resulting microstructures were compared to as-solidified and reflow cycled Sn-Ag-Cu spheres (450 μm diameter) as well as as-solidified Sn-Ag-Cu, Sn-Cu, and Sn-Ag microstructures from the literature. Previous literature observations reporting reductions in undercooling and β-Sn grain size with Al micro-alloying additions could not be correlated to the presence of the Cu9Al4 phase or Al solute. The as-solidified spheres displayed no change in β-Sn dendrite structure or grain size when compared to non-Al-modified alloys, and the reflow cycled spheres produced high undercoolings (22-64°C), indicating a lack of potent nucleation sites. The current findings highlighted the role of Ag in the formation of the interlaced twinning structure and demonstrated that with deliberate compositional choices, formation of the alloy's β-Sn grain structure (cyclical twinning versus interlaced twinning) could be influenced, in both the as-solidified and reflow cycled states, though still not producing the fine-grain sizes and multiple orientations desired for improved thermomechanical properties.

  2. Effect of magnesium content on the microstructure and dry sliding wear behavior of centrifugally cast functionally graded A356-Mg2Si in situ composites

    Science.gov (United States)

    Ram, Subhash Chandra; Chattopadhyay, K.; Chakrabarty, I.

    2018-04-01

    Functionally graded A356 alloy (Al–7.2Si–0.3Mg) –Mg2Si in situ composites have been synthesized via centrifugal casting route. Mg2Si particles tend to migrate towards the core of the tubular product by centrifugal force. The in situ formed Mg2Si particles in composites are characterized by x-ray diffraction (XRD) analysis, Energy dispersive spectrometry (EDS), Optical, Scanning Electron and Transmission Electron Microscopy. Apart from primary blocky Mg2Si particles the matrix contains other phases viz. Al-Si eutectic, pseudo-binary Al-Mg2Si eutectic and Al-Fe-Si intermetallics. Density is found to decrease and %porosity is increased with increase in volume fraction of Mg2Si. Maximum hardness was observed at the inner core region due to maximum segregation of Mg2Si particles and gradually decreases towards the outer periphery region. The dry sliding wear was evaluated with varying parameters such as normal loads (N) and sliding distances (m). A substantial increase in wear resistance at the inner core region is observed. From the worn surface characterization, the wear mechanisms have been explained.

  3. In-situ formation of Ni4Ti3 precipitate and its effect on pseudoelasticity in selective laser melting additive manufactured NiTi-based composites

    Science.gov (United States)

    Gu, Dongdong; Ma, Chenglong

    2018-05-01

    Selective laser melting (SLM) additive manufacturing technology was applied to synthesize NiTi-based composites via using ball-milled Ti, Ni, and TiC mixed powder. By transmission electron microscope (TEM) characterization, it indicated that the B2 (NiTi) matrix was obtained during SLM processing. In spite of more Ti content (the Ti/Ni ratio >1), a mass of Ni-rich intermetallic compounds containing Ni4Ti3 with nanostructure features and eutectic Ni3Ti around in-situ Ti6C3.75 dendrites were precipitated. Influence of the applied laser volume energy density (VED) on the morphology and content of Ni4Ti3 precipitate was investigated. Besides, nanoindentation test of the matrix was performed in order to assess pseudoelastic recovery behavior of SLM processed NiTi-based composites. At a relatively high VED of 533 J/mm3, the maximum pseudoelastic recovery was obtained due to the lowest content of Ni4Ti3 precipitates. Furthermore, the precipitation mechanism of in-situ Ni4Ti3 was present based on the redistribution of titanium element and thermodynamics analysis, and then the relationship of Ni4Ti3 precipitate, VED and pseudoelastic recovery behavior was also revealed.

  4. In-situ synthesized Ni–Zr intermetallic/ceramic reinforced composite coatings on zirconium substrate by high power diode laser

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kun; Li, Yajiang, E-mail: yajli@sdu.edu.cn; Wang, Juan; Ma, Qunshuang

    2015-03-05

    Highlights: • In-situ synthesized Ni–Zr intermetallics/ceramic reinforced composite coatings. • Si enrichment and Ni replacing site of Si both resulted in forming Zr{sub 5}(Si{sub x}Ni{sub 1−x}){sub 4.} • Microstructure and forming of ZrB{sub 2} depended on affinity of elements and Si/B ratio. - Abstract: Ni–Zr intermetallic/ceramic reinforced composite coatings were in-situ synthesized by laser cladding series of Ni–Cr–B–Si powders on zirconium substrate. Microstructure, phase constituents and microhardness of coatings were investigated by means of optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and microsclemeter. Results indicated that coatings with metallurgical bonding to substrate consisted of cellular NiZr matrix and massive reinforcements including NiZr{sub 2}, Zr{sub 5}(Si{sub x}Ni{sub 1−x}){sub 4} and ZrB{sub 2}. Morphologies of reinforcements were mainly dominated by temperature gradient and cooling rate from surface to bottom of the coating produced by same powder. In different coatings, microstructure and forming of ZrB{sub 2} mainly depended on affinity of elements and Si/B ratio in different powders. In addition, the mean microhardness of coatings up to 1200–1300 HV{sub 0.2} is nearly 7 times higher than that of R60702 zirconium substrate.

  5. In-Situ Compositional Analysis and Provenance Study of the Historic Terengganu Stone (“Batu Bersurat Piagam Terengganu”) Using Neutron-Induced Prompt Gamma-Ray Techniques

    International Nuclear Information System (INIS)

    Abdullah, J.; Yahya, R.; Dahing, N. S.; Shaari, M. R.; Mahmood, A. A.; Hassan, H.; Jamaluddin, T. A.; Abdullah, M. Y.; Mahmud, N. A.; Mosorov, V.

    2018-01-01

    Terengganu inscribed stone is the oldest artifact with Jawi writing on it. It is a most treasured heritage for the history of Malaysian civilisation. The artifact proves that the Kingdom of Terengganu exist earlier than 1326 or 1386. It was accidentally discovered near Tersat River at Kampong Buluh, Kuala Berang, Terengganu, Malaysia by a gold & tin trader after a flash flood hit Kuala Berang in 1902.The inscription turned out to be a proclamation issued by the ''Sri Paduka Tuan'' of Terengganu. The significant is the date on the first face of the inscription, which is given as the year 1303 AD. This project focuses on the development of in-situ compositional analysis and provenance study of the Inscribed Terengganu Stone using Neutron-Induced Prompt Gamma-Ray Techniques (NIPGAT). To date, a lot of studies have been carried out by historians and archaeologists about the content of the inscription, but no scientific investigation about the material composition and its provenance has been performed. In this project, an instrumental analysis NIPGAT was designed as a portable non-destructive investigation tool employing an isotopic neutron source (Cf-252) and a gamma-ray spectroscopy system for in-situ investigation of the Inscribed Stone. (author)

  6. High-Temperature Tensile and Tribological Behavior of Hybrid (ZrB2+Al3Zr)/AA5052 In Situ Composite

    Science.gov (United States)

    Gautam, G.; Kumar, N.; Mohan, A.; Gautam, R. K.; Mohan, S.

    2016-09-01

    During service life, components such as piston, cylinder blocks, brakes, and discs/drums, have to work under high-temperature conditions. In order to have appropriate material for such applications high-temperature studies are important. Hybrid (ZrB2+Al3Zr)/AA5052 in situ composite has been investigated from ambient to 523 K (250 °C) at an interval of 50 deg. (ZrB2+Al3Zr)/AA5052 in situ composite has been fabricated by the direct melt reaction of AA5052 alloy with zirconium and boron salts. Microstructure studies show refinement in the grain size of base alloy on in situ formation of reinforcement particles. Al3Zr particles are observed in rectangular and polyhedron shapes. It is observed from the tensile studies that ultimate tensile strength, yield strength, and percentage elongation decrease with increase in test temperature. Similar kind of behavior is also observed for flow curve properties. The tensile results have also been correlated with fractography. Wear and friction results indicate that the wear rate increases with increase in normal load, whereas coefficient of friction shows decreasing trend. With increasing test temperature, wear rate exhibits a typical phenomenon. After an initial increase, wear rate follows a decreasing trend up to 423 K (150 °C), and finally a rapid increase is observed, whereas coefficient of friction increases continuously with increase in test temperature. The mechanisms responsible for the variation of wear and friction with different temperatures have been discussed in detail with the help of worn surfaces studies under scanning electron microscope (SEM) & 3D-profilometer and debris analysis by XRD.

  7. Compositional and structural changes in TiB2 films induced by bias, in situ and post-deposition annealing, respectively

    International Nuclear Information System (INIS)

    Pelleg, Joshua; Sade, G.; Sinder, M.; Mogilyanski, D.

    2006-01-01

    Structural changes in TiB 2 films were induced at relatively low temperatures by the application of bias and in situ annealing or by post-deposition heat treatment of samples subjected to bias with simultaneous in situ annealing. In situ annealing by itself evoked only partial crystallization. Application of bias by itself only modified the composition of the as deposited film. A simple model is presented to explain the variation of the composition when RF bias is applied to a cold substrate. The crystallized films had a (0001) texture. A model has been suggested to explain the observed preferred orientation, based on the contribution of surface and strain energies. Both, the surface energy and strain energy are direction dependent. These were evaluated for two film orientations reported in the literature, namely, the (0001) and (101-bar 1)orientations. The preferred orientation of the film is determined by the lowest overall free energy resulting from the competition between the surface energy and the strain energy on different lattice planes. The surface energy is not film thickness dependent while the strain energy is thickness dependent and increases with it. For small film thickness, as in this work, the surface energy term is significant and (0001) orientation with a minimum surface energy is preferred. At large film thicknesses the strain energy becomes dominant and the (101-bar 1) preferred orientation is observed. Under certain experimental conditions strain energy effects may tip the preferred orientation to (101-bar 1). The elastic moduli in the (0001) and (101-bar 1) directions were determined as 435 and 538GPa, respectively

  8. 30 CFR 77.1111 - Welding, cutting, soldering; use of fire extinguisher.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Welding, cutting, soldering; use of fire... OF UNDERGROUND COAL MINES Fire Protection § 77.1111 Welding, cutting, soldering; use of fire extinguisher. One portable fire extinguisher shall be provided at each location where welding, cutting, or...

  9. Tissue soldering with biodegradable polymer films: in-vitro investigation of hydration effects on weld strength

    Science.gov (United States)

    Sorg, Brian S.; Welch, Ashley J.

    2001-05-01

    Previous work demonstrated increased breaking strengths of tissue repaired with liquid albumin solder reinforced with a biodegradable polymer film compared to unreinforced control specimens. It was hypothesized that the breaking strength increase was due to reinforcement of the liquid solder cohesive strength. Immersion in a moist environment can decrease the adhesion of solder to tissue and negate any strength benefits gained from reinforcement. The purpose of this study was to determine if hydrated specimens repaired with reinforced solder would still be stronger than unreinforced controls. A 50%(w/v) bovine serum albumin solder with 0.5 mg/mL Indocyanine Green dye was used to repair an incision in bovine aorta. The solder was coagulated with 806-nm diode laser light. A poly(DL-lactic- co-glycolic acid) film was used to reinforce the solder (the controls had no reinforcement). The repaired tissues were immersed in phosphate buffered saline for time periods of 1 and 2 days. The breaking strengths of all of the hydrated specimens decreased compared to the acute breaking strengths. However, the reinforced specimens still had larger breaking strengths than the unreinforced controls. These results indicate that reinforcement of a liquid albumin solder may have the potential to improve the breaking strength in a clinical setting.

  10. Current Problems and Possible Solutions in High-Temperature Lead-Free Soldering

    Czech Academy of Sciences Publication Activity Database

    Kroupa, Aleš; Andersson, D.; Hoo, N.; Pearce, J.; Watson, A.; Dinsdale, A.; Mucklejohn, S.

    2012-01-01

    Roč. 21, č. 5 (2012), s. 629-637 ISSN 1059-9495 Institutional support: RVO:68081723 Keywords : lead-free soldering, * materials for high-temperature LF * new technologies for HT lead-free soldering Subject RIV: BJ - Thermodynamics Impact factor: 0.915, year: 2012

  11. Effect of Strain Rate on Joint Strength and Failure Mode of Lead-Free Solder Joints

    Science.gov (United States)

    Lin, Jian; Lei, Yongping; Fu, Hanguang; Guo, Fu

    2018-03-01

    In surface mount technology, the Sn-3.0Ag-0.5Cu solder joint has a shorter impact lifetime than a traditional lead-tin solder joint. In order to improve the impact property of SnAgCu lead-free solder joints and identify the effect of silver content on tensile strength and impact property, impact experiments were conducted at various strain rates on three selected SnAgCu based solder joints. It was found that joint failure mainly occurred in the solder material with large plastic deformation under low strain rate, while joint failure occurred at the brittle intermetallic compound layer without any plastic deformation at a high strain rate. Joint strength increased with the silver content in SnAgCu alloys in static tensile tests, while the impact property of the solder joint decreased with increasing silver content. When the strain rate was low, plastic deformation occurred with failure and the tensile strength of the Sn-3.0Ag-0.5Cu solder joint was higher than that of Sn-0.3Ag-0.7Cu; when the strain rate was high, joint failure mainly occurred at the brittle interface layer and the Sn-0.3Ag-0.7Cu solder joint had a better impact resistance with a thinner intermetallic compound layer.

  12. Development of technique for laser welding of biological tissues using laser welding device and nanocomposite solder.

    Science.gov (United States)

    Gerasimenko, A; Ichcitidze, L; Podgaetsky, V; Ryabkin, D; Pyankov, E; Saveliev, M; Selishchev, S

    2015-08-01

    The laser device for welding of biological tissues has been developed involving quality control and temperature stabilization of weld seam. Laser nanocomposite solder applied onto a wound to be weld has been used. Physicochemical properties of the nanocomposite solder have been elucidated. The nature of the tissue-organizing nanoscaffold has been analyzed at the site of biotissue welding.

  13. Failure Mechanisms of SAC/Fe-Ni Solder Joints During Thermal Cycling

    Science.gov (United States)

    Gao, Li-Yin; Liu, Zhi-Quan; Li, Cai-Fu

    2017-08-01

    Thermal cycling tests have been conducted on Sn-Ag-Cu/Fe- xNi ( x = 73 wt.% or 45 wt.%) and Sn-Ag-Cu/Cu solder joints according to the Joint Electron Device Engineering Council industrial standard to study their interfacial reliability under thermal stress. The interfacial intermetallic compounds formed for solder joints on Cu, Fe-73Ni, and Fe-45Ni were 4.5 μm, 1.7 μm, and 1.4 μm thick, respectively, after 3000 cycles, demonstrating excellent diffusion barrier effect of Fe-Ni under bump metallization (UBM). Also, two deformation modes, viz. solder extrusion and fatigue crack formation, were observed by scanning electron microscopy and three-dimensional x-ray microscopy. Solder extrusion dominated for solder joints on Cu, while fatigue cracks dominated for solder joints on Fe-45Ni and both modes were detected for those on Fe-73Ni. Solder joints on Fe-Ni presented inferior reliability during thermal cycling compared with those on Cu, with characteristic lifetime of 3441 h, 3190 h, and 1247 h for Cu, Fe-73Ni, and Fe-45Ni UBM, respectively. This degradation of the interfacial reliability for solder joints on Fe-Ni is attributed to the mismatch in coefficient of thermal expansion (CTE) at interconnection level. The CTE mismatch at microstructure level was also analyzed by electron backscatter diffraction for clearer identification of recrystallization-related deformation mechanisms.

  14. Corrosion Reliability of Lead-free Solder Systems Used in Electronics

    DEFF Research Database (Denmark)

    Li, Feng; Verdingovas, Vadimas; Medgyes, Balint

    2017-01-01

    humidity/temperature cycling tests on soldered surface insulation resistance (SIR) comb pattern. Complimentary microstructural and phase analysis of solder alloys has been carried out using the scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) methods...

  15. Reliability and microstructure of lead-free solder joints in industrial electronics after accelerated thermal aging

    NARCIS (Netherlands)

    Scaltro, F.; Biglari, M.H.; Kodentsov, A.; Yakovleva, O.; Brom, E.

    2009-01-01

    The reliability of lead-free (LF) solder joints in surface-mounted device components (SMD) has been investigated after thermo-cycle testing. Kirkendall voids have been observed at the interface component/solder together with the formation of fractures. The evolution, the morphology and the elemental

  16. Investigation of moisture uptake into printed circuit board laminate and solder mask materials

    DEFF Research Database (Denmark)

    Conseil, Helene; Gudla, Visweswara Chakravarthy; Borgaonkar, Shruti

    2017-01-01

    with different solder mask materials and exposed to saturated water vapour and liquid water. The solder masks are characterised for their microstructure and constituent phases using scanning electron microscopy and X-ray diffraction. The observations are correlated with themoisture absorption characteristic...

  17. Multi-scale modeling of elasto-plastic response of SnAgCu lead-free solder alloys at different ageing conditions: Effect of microstructure evolution, particle size effects and interfacial failure

    Energy Technology Data Exchange (ETDEWEB)

    Maleki, Milad; Cugnoni, Joel, E-mail: joel.cugnoni@epfl.ch; Botsis, John

    2016-04-20

    In microelectronics applications, SnAgCu lead-free solder joints play the important role of ensuring both the mechanical and electrical integrity of the components. In such applications, the SnAgCu joints are subjected to elevated homologous temperatures for an extended period of time causing significant microstructural changes and leading to reliability issues. In this study, the link between the change in microstructures and deformation behavior of SnAgCu solder during ageing is explained by developing a hybrid multi-scale microstructure-based modeling approach. Herein, the SnAgCu solder alloy is seen as a three phase metal matrix composite in which Ag{sub 3}Sn and Cu{sub 6}Sn{sub 5} hard intermetallics play the role of reinforcements and Sn the role of a ductile matrix. The hardening of the Sn matrix due to fine intermetallics in the eutectic mixture is modeled by incorporating the mean field effects of geometrically necessary dislocations. Subsequently, a two level homogenization procedure based on micromechanical finite element (FE) models is used to capture the interactions between the different phases. For this purpose, tomographic images of microstructures obtained by Focused Ion Beam (FIB) and synchrotron X-Ray in different ageing conditions are directly used to generate statistically representative volume elements (RVE) using 3D FE models. The constitutive behavior of the solder is determined by sequentially performing two scales of numerical homogenization at the eutectic level and then at the dendrite level. For simplification, the anisotropy of Sn as well as the potential recovery processes have been neglected in the modeling. The observed decrease in the yield strength of solder due to ageing is well captured by the adopted modeling strategy and allows explaining the different ageing mechanisms. Finally, the effects of potential debonding at the intermetallic particle-matrix interface as well as particle fracture on the overall strength of solder are

  18. A composite of polyelectrolyte-grafted multi-walled carbon nanotubes and in situ polymerized polyaniline for the detection of low concentration triethylamine vapor

    International Nuclear Information System (INIS)

    Li Yang; Wang Huicai; Cao Xiehong; Yuan Minyong; Yang Mujie

    2008-01-01

    Multi-walled carbon nanotubes (MWNTs) grafted with sodium polystyrenesulfonate (NaPSS) were deposited on an interdigitated gold electrode decorated with a layer of positively charged poly(diallyldimethylammonium chloride) by a self-assembly method. Then polyaniline (PANI) was in situ polymerized on the surface of the MWNTs to prepare a composite. The structure and morphology of the composite were investigated by Raman spectroscopy and scanning electron microscopy. The electrical responses of the composite to triethylamine vapor of low concentrations were measured at room temperature. It was found that the composite exhibited a linear response to the vapor in the range of 0.5-8 ppm with the highest sensitivity of ∼80%, which is much higher than that of MWNTs and PANI separately, and an obvious synergetic effect was observed. In addition, the detection limit was as low as the ppb level, and reversible and relatively fast responses (t 90% ∼200 s and ∼10 min for sensing and recovery, respectively) were observed. The sensing characteristics are highly related to the gas responses of PANI, and a sensing mechanism considering the interaction of MWNTs and PANI was proposed

  19. Propagation of PAMAM dendrimers on the carbon fiber surface by in situ polymerization: a novel methodology for fiber/matrix composites

    International Nuclear Information System (INIS)

    Zhang, R.L.; Gao, B.; Zhang, J.; Cui, H.Z.; Li, D.W.

    2015-01-01

    Graphical abstract: - Highlights: • The manuscript has the following obvious new contributions. • A facile strategy to generating dendrimers onto carbon fibers to functionalize conventional carbon fibers was reported. The density and type of the functional groups on the fiber surface can be easily adjusted by changing the reaction conditions. • The hierarchical reinforcement formed using this novel method improved the composite interface bonding through supplying sufficient chemical bonding and strong mechanical interlocking. • We can generate dendrimers with different side groups (unsaturated groups or hydroxyl groups, and others) and chain length to meet the requirements according to different matrices and applications. - Abstract: A facile strategy for generating dendrimers onto carbon fibers, in order to functionalize them, was reported. Dendrimers were propagated on the surface of carbon fibers by in situ polymerization with Michael addition. The changes in morphology, surface composition and surface energy, which were studied by atomic force microscope (AFM), dynamic contact angle analysis test (DCAT) and x-ray photoelectron microscopy (XPS), were related to the interfacial performance of model composites. In addition, the level of fiber-matrix adhesion was determined by the interlaminar shear strength (ILSS) test. Experimental results indicated that some dendritic polymer was successfully grown on the fiber surface through the chemical reaction, and this significantly enhanced the interfacial bonding of the carbon fiber composites.

  20. In situ electrochemical polymerization of a nanorod-PANI-Graphene composite in a reverse micelle electrolyte and its application in a supercapacitor.

    Science.gov (United States)

    Hu, Liwen; Tu, Jiguo; Jiao, Shuqiang; Hou, Jungang; Zhu, Hongmin; Fray, Derek J

    2012-12-05

    Highly porous nanorod-PANI-Graphene composite films were prepared by in situ electrochemical polymerization onto an ITO substrate in a reverse micelle electrolyte. The morphology and microstructure of the composite films were analyzed by using a field emission scanning electron microscope. It was observed that the films were highly porous and the nanorod PANI films were inserted by graphene nanosheets. This indicated that a good conductive network between PANI nanorods and graphene sheets was formed. Further electrochemical tests involved cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 1 mol L(-1) HClO(4) solution. The results showed that the composite film had a favorable capacitance with a high electron transfer rate and low resistance. The highest specific capacitance that could be achieved was as high as 878.57 F g(-1) with the charge loading of 500 mC at a current density of 1 A g(-1). The GCD at different charge loadings showed good cycle stability with a low fading rate of specific capacitance after 1000 cycles. The results demonstrated that the nanorod-PANI-Graphene composite was proved to be of great potential as an electrode material for supercapacitors.

  1. In-situ sulfuration synthesis of sandwiched spherical tin sulfide/sulfur-doped graphene composite with ultra-low sulfur content

    Science.gov (United States)

    Zhao, Bing; Yang, Yaqing; Wang, Zhixuan; Huang, Shoushuang; Wang, Yanyan; Wang, Shanshan; Chen, Zhiwen; Jiang, Yong

    2018-02-01

    SnS is widely studied as anode materials since of its superior structural stability and physicochemical property comparing with other Sn-based composites. Nevertheless, the inconvenience of phase morphology control and excessive consumption of sulfur sources during synthesis hinder the scalable application of SnS nanocomposites. Herein, we report a facile in-situ sulfuration strategy to synthesize sandwiched spherical SnS/sulfur-doped graphene (SnS/S-SG) composite. An ultra-low sulfur content with approximately stoichiometric ratio of Sn:S can effectively promote the sulfuration reaction of SnO2 to SnS and simultaneous sulfur-doping of graphene. The as-prepared SnS/S-SG composite shows a three-dimensional interconnected spherical structure as a whole, in which SnS nanoparticles are sandwiched between the multilayers of graphene sheets forming a hollow sphere. The sandwiched sphere structure and high S doping amount can improve the binding force between SnS and graphene, as well as the structural stability and electrical conductivity of the composite. Thus, a high reversibility of conversion reaction, promising specific capacity (772 mAh g-1 after 100 cycles at 0.1 C) and excellent rate performance (705 and 411 mAh g-1 at 1 C and 10 C, respectively) are exhibited in the SnS/S-SG electrode, which are much higher than that of the SnS/spherical graphene synthesized by traditional post-sulfuration method.

  2. Utilization of poly(methyl methacrylate – carbon nanotube and polystyrene – carbon nanotube in situ polymerized composites as masterbatches for melt mixing

    Directory of Open Access Journals (Sweden)

    M. Lahelin

    2012-10-01

    Full Text Available Carbon nanotubes (CNTs were melt mixed directly or by using an in situ polymerized masterbatch into a matrix polymer, polystyrene (PS or poly(methyl methacrylate (PMMA. The mechanical properties of the composites were mostly determined by the amount of CNTs, and not by the use of directly melt mixed CNTs or the use of the masterbatch. In contrast, the electrical resistivity of the composites was dependent on the manner in which the CNTs were added to the matrix polymer. When there was increased interfacial adhesion between the components, as for PS and the CNTs, the use of directly melt mixed CNTs gave better resistivity results. Without strong interactions between the CNTs and the matrix, as with PMMA and CNTs, the use of a tailored masterbatch had a significant effect on properties of the final composites. The molecular weight and viscosity of masterbatches can be varied and when the PMMA-masterbatch had optimized viscosity with respect to the PMMA matrix, electrical resistivity of the final composites decreased noticeably.

  3. In-situ grown CNTs modified SiO2/C composites as anode with improved cycling stability and rate capability for lithium storage

    Science.gov (United States)

    Wang, Siqi; Zhao, Naiqin; Shi, Chunsheng; Liu, Enzuo; He, Chunnian; He, Fang; Ma, Liying

    2018-03-01

    Silica (SiO2) is regarded as one of the most promising anode materials for lithium ion batteries owing to its high theoretical specific capacity, relatively low operation potentials, abundance, environmental benignity and low cost. However, the low intrinsic electrical conductivity and large volume change of SiO2 during the discharge/charge cycles usually results in poor electrochemical performance. In this work, carbon nanotubes (CNTs) modified SiO2/C composites have been fabricated through an in-situ chemical vapor deposition method. The results show that the electrical conductivity of the SiO2/C/CNTs is visibly enhanced through a robust connection between the CNTs and SiO2/C particles. Compared with the pristine SiO2 and SiO2/C composites, the SiO2/C/CNTs composites display a high initial capacity of 1267.2 mA h g-1. Besides, an excellent cycling stability with the capacity of 315.7 mA h g-1 is achieved after 1000th cycles at a rate of 1 A g-1. The significantly improved electrochemical properties of the SiO2/C/CNTs composites are mainly attributed to the formation of three dimensional CNT networks in the SiO2/C substrate, which can not only shorten the Li-ion diffusion path but also relieve the volume change during the lithium-ion insertion/extraction processes.

  4. Cooling thermal parameters and microstructure features of directionally solidified ternary Sn–Bi–(Cu,Ag) solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Bismarck L., E-mail: bismarck_luiz@yahoo.com.br [Department of Materials Engineering, Federal University of São Carlos, UFSCar, 13565-905 São Carlos, SP (Brazil); Garcia, Amauri [Department of Manufacturing and Materials Engineering, University of Campinas, UNICAMP, 13083-860 Campinas, SP (Brazil); Spinelli, José E. [Department of Materials Engineering, Federal University of São Carlos, UFSCar, 13565-905 São Carlos, SP (Brazil)

    2016-04-15

    Low temperature soldering technology encompasses Sn–Bi based alloys as reference materials for joints since such alloys may be molten at temperatures less than 180 °C. Despite the relatively high strength of these alloys, segregation problems and low ductility are recognized as potential disadvantages. Thus, for low-temperature applications, Bi–Sn eutectic or near-eutectic compositions with or without additions of alloying elements are considered interesting possibilities. In this context, additions of third elements such as Cu and Ag may be an alternative in order to reach sounder solder joints. The length scale of the phases and their proportions are known to be the most important factors affecting the final wear, mechanical and corrosions properties of ternary Sn–Bi–(Cu,Ag) alloys. In spite of this promising outlook, studies emphasizing interrelations of microstructure features and solidification thermal parameters regarding these multicomponent alloys are rare in the literature. In the present investigation Sn–Bi–(Cu,Ag) alloys were directionally solidified (DS) under transient heat flow conditions. A complete characterization is performed including experimental cooling thermal parameters, segregation (XRF), optical and scanning electron microscopies, X-ray diffraction (XRD) and length scale of the microstructural phases. Experimental growth laws relating dendritic spacings to solidification thermal parameters have been proposed with emphasis on the effects of Ag and Cu. The theoretical predictions of the Rappaz-Boettinger model are shown to be slightly above the experimental scatter of secondary dendritic arm spacings for both ternary Sn–Bi–Cu and Sn–Bi–Ag alloys examined. - Highlights: • Dendritic growth prevailed for the ternary Sn–Bi–Cu and Sn–Bi–Ag solder alloys. • Bi precipitates within Sn-rich dendrites were shown to be unevenly distributed. • Morphology and preferential region for the Ag{sub 3}Sn growth depend on Ag

  5. Properties and Microstructures of Sn-Bi-X Lead-Free Solders

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2016-01-01

    Full Text Available The Sn-Bi base lead-free solders are proposed as one of the most popular alloys due to the low melting temperature (eutectic point: 139°C and low cost. However, they are not widely used because of the lower wettability, fatigue resistance, and elongation compared to traditional Sn-Pb solders. So the alloying is considered as an effective way to improve the properties of Sn-Bi solders with the addition of elements (Al, Cu, Zn, Ga, Ag, In, Sb, and rare earth and nanoparticles. In this paper, the development of Sn-Bi lead-free solders bearing elements and nanoparticles was reviewed. The variation of wettability, melting characteristic, electromigration, mechanical properties, microstructures, intermetallic compounds reaction, and creep behaviors was analyzed systematically, which can provide a reference for investigation of Sn-Bi base solders.

  6. Effects of temperature and loading speed on interface-dominated strength in fibre/polymer composites: An evaluation for in-situ environment

    International Nuclear Information System (INIS)

    Sethi, Sanghamitra; Rathore, Dinesh Kumar; Ray, Bankim Chandra

    2015-01-01

    Graphical abstract: Some microcracks turn to potential cracks at low loading rates and cause significant reduction in interlaminar shear strength of the composite system while as the loading rate increases the time available to propagate the microcracks is less. This can be attributed to higher ILSS at higher loading rates at these above-ambient temperatures. - Highlights: • Effect of temperature and loading rate has been studied. • Three different types of fibres are used for fabrication. • Flexural and fractography behaviour were studied. • T g was affected by types of fibre and matrix used. - Abstract: The present investigation intends to study the influence of crosshead velocity and in-situ environmental conditioning i.e. high temperature and cryogenic temperature on micromechanical performance of glass fibre/epoxy, carbon fibre/epoxy and Kevlar fibre/epoxy polymer composites. 3-point short beam shear tests were conducted on the conditioned specimens to evaluate the interfacial properties and failure modes which are related to mechanical properties of the composites. The effect of crosshead velocity (within the range 1-10 3 mm/min) on the interlaminar shear strength (ILSS) of all the three composite systems at different temperatures was studied. The glass transition temperature (T g ) of conditioned samples were measured by differential scanning calorimetry (DSC) in the temperature range of 25 °C to 150 °C temperature. At 1 mm/min loading rate, for both glass/epoxy and carbon/epoxy composites maximum increase in ILSS value was about 85.72% with respect to ambient, while for Kevlar/epoxy composite 31.77% reduction in ILSS was observed at -100 °C temperature

  7. Microstructure and tensile properties of in situ synthesized (TiB+Y2O3)/Ti composites at elevated temperature

    International Nuclear Information System (INIS)

    Geng Ke; Lu Weijie; Zhang Di

    2003-01-01

    A novel titanium matrix composites reinforced with TiB and rare earth oxides (Y 2 O 3 ) were prepared by a non-consumable arc-melting technology. Microstructures of the composites were observed by means of optical microscope (OM) and transmission electron microscope (TEM). X-ray diffraction (XRD) was used to identify the phases in the composites. There are three phases: TiB, Y 2 O 3 and titanium matrix alloy. TiB grows in needle shape, whereas Y 2 O 3 grows from near-equiaxed shape to dendritic shape with increase of yttrium content in the composite. The interfaces between reinforcements and titanium matrix are very clear. There is no interfacial reaction. Tensile properties of the composites were tested at 773, 823 and 873 K. Both the fracture surfaces and longitudinal sections of the fractured tensile specimens were comprehensively examined by scanning electron microscope (SEM). The fracture mode and fracture process at different temperatures were analyzed and explained. The results show that the tensile strength of the composites has a significant improvement at elevated temperatures. The predominant fracture mode of composites is cleavaged at 773 and 823 K. Fracture occurs by ductile failure at 873 K

  8. Towards the improvement of the oxidation resistance of Nb-silicides in situ composites: A solid state diffusion approach

    International Nuclear Information System (INIS)

    Mathieu, S.; Knittel, S.; François, M.; Portebois, L.; Mathieu, S.; Vilasi, M.

    2014-01-01

    Highlights: •Local equilibrium is attained during oxidation at phase boundaries (steady state conditions). •A solid state diffusion model explains the oxidation mechanism of Nb-silicides composites. •The Nb ss fraction is not the only parameters governing the oxidation rate of Nb-silicides. •Aluminium increases the thermodynamic activity of Si in the Nb-silicides composites. •The results indicate the need to develop a Nb–Ti–Hf–Al–Cr–Si thermodynamic database. -- Abstract: The present study focuses on the oxidation mechanism of Nb-silicide composites and on the effect of the composition on the oxidation rate at 1100 °C. A theoretical approach is proposed based on experimental results and used to optimise the oxidation resistance. The growth model based on multiphase diffusion was experimentally tested and confirmed by manufacturing seven composites with different compositions. It was also found that the effect of the composition has to be evaluated at 1100 °C within a short time duration (50 h), where the oxide scale and the internal oxidation zone both grow according to parabolic kinetics

  9. Effect of phosphorus element on the comprehensive properties of Sn-Cu lead-free solder

    International Nuclear Information System (INIS)

    Li Guangdong; Shi Yaowu; Hao Hu; Xia Zhidong; Lei Yongping; Guo Fu

    2010-01-01

    In the present work, the effect of phosphorus on the creep fatigue properties of Sn-Cu eutectic lead-free solder was carried out. The experimental results show that the melting temperature was almost not changed with adding small amount of P element. However, the addition of trace P element led to the decrease in the property of creep fatigue. The fractography analysis by a scanning electron microscopy (SEM) shows that ductile fracture was the dominant failure behavior in the process of creep fatigue test of Sn0.7Cu and Sn0.7Cu0.005P specimens. It should be pointed out that there is significant difference in the fractographs between the joints of Sn0.7Cu solder and Sn0.7Cu0.005P solder. In the fractograph of Sn0.7Cu solder joint, the microstructure is prolonged along testing direction, and the dimples were more than the fractograph of Sn0.7Cu0.005P solder joint. In addition, the voids could be found on the Sn0.7Cu0.005P solder joint, and trace P addition may increase the rate of forming void of Sn0.7Cu solder joint. The voids can potentially lead to crack initiation or propagation sites in the solder joint. As a result, the creep fatigue of solder joint containing P such as Sn0.7Cu0.005P offers worse property compared to Sn0.7Cu solder joint.

  10. Physical properties of lead free solders in liquid and solid state

    Energy Technology Data Exchange (ETDEWEB)

    Mhiaoui, Souad

    2007-04-17

    The European legislation prohibits the use of lead containing solders in Europe. However, lead free solders have a higher melting point (typical 20%) and their mechanical characteristics are worse. Additional problems are aging and adhesion of the solder on the electronic circuits. Thus, research activities must focus on the optimization of the properties of Sn-Ag-Cu based lead free solders chosen by the industry. Two main objectives are treated in this work. In the center of the first one is the study of curious hysteresis effects of metallic cadmium-antimony alloys after thermal cycles by measuring electronic transport phenomena (thermoelectric power and electrical resistivity). The second objective, within the framework of ''cotutelle'' between the universities of Metz and of Chemnitz and supported by COST531, is to study more specifically lead free solders. A welding must well conduct electricity and well conduct and dissipate heat. In Metz, we determined the electrical conductivity, the thermoelectric power and the thermal conductivity of various lead free solders (Sn-Ag-Cu, Sn-Cu, Sn-Ag, Sn-Sb) as well in the liquid as well in the solid state. The results have been compared to classical lead-tin (Pb-Sn) solders. In Chemnitz we measured the surface tension, the interfacial tension and the density of lead free solders. We also measured the viscosity of these solders without and with additives, in particular nickel. These properties were related to the industrial problems of wettability and spreadability. Lastly, we solidified alloys under various conditions. We observed undercooling. We developed a technique of mixture of nanocrystalline powder with lead free solders ''to sow'' the liquid bath in order to obtain ''different'' solids which were examined using optical and electron microscopy. (orig.)

  11. Effect of phosphorus element on the comprehensive properties of Sn-Cu lead-free solder

    Energy Technology Data Exchange (ETDEWEB)

    Li Guangdong, E-mail: liguangdong@emails.bjut.edu.c [College of Materials Science and Engineering, Beijing University of Technology, 100 Ping Le Yuan, Chaoyang District, Beijing 100124 (China); Shi Yaowu; Hao Hu; Xia Zhidong; Lei Yongping; Guo Fu [College of Materials Science and Engineering, Beijing University of Technology, 100 Ping Le Yuan, Chaoyang District, Beijing 100124 (China)

    2010-02-18

    In the present work, the effect of phosphorus on the creep fatigue properties of Sn-Cu eutectic lead-free solder was carried out. The experimental results show that the melting temperature was almost not changed with adding small amount of P element. However, the addition of trace P element led to the decrease in the property of creep fatigue. The fractography analysis by a scanning electron microscopy (SEM) shows that ductile fracture was the dominant failure behavior in the process of creep fatigue test of Sn0.7Cu and Sn0.7Cu0.005P specimens. It should be pointed out that there is significant difference in the fractographs between the joints of Sn0.7Cu solder and Sn0.7Cu0.005P solder. In the fractograph of Sn0.7Cu solder joint, the microstructure is prolonged along testing direction, and the dimples were more than the fractograph of Sn0.7Cu0.005P solder joint. In addition, the voids could be found on the Sn0.7Cu0.005P solder joint, and trace P addition may increase the rate of forming void of Sn0.7Cu solder joint. The voids can potentially lead to crack initiation or propagation sites in the solder joint. As a result, the creep fatigue of solder joint containing P such as Sn0.7Cu0.005P offers worse property compared to Sn0.7Cu solder joint.

  12. An Approach for Impression Creep of Lead Free Microelectronic Solders

    Science.gov (United States)

    Anastasio, Onofrio A.

    2002-06-01

    Currently, the microelectronics industry is transitioning from lead-containing to lead-free solders in response to legislation in the EU and Japan. Before an alternative alloy can be designated as a replacement for current Pb-Sn extensive testing must be accomplished. One major characteristic of the alloy that must be considered is creep. Traditionally, creep testing requires numerous samples and a long tin, which thwarts the generation of comprehensive creep databases for difficult to prepare samples such as microelectronic solder joints. However, a relatively new technique, impression creep enables us to rapidly generate creep data. This test uses a cylindrical punch with a flat end to make an impression on the surface of a specimen under constant load. The steady state velocity of the indenter is found to have the same stress and temperature dependence as the conventional unidirectional creep test using bulk specimens. This thesis examines impression creep tests of eutectic Sn-Ag. A testing program and apparatus was developed constructed based on a servo hydraulic test frame. The apparatus is capable of a load resolution of 0.01N with a stability of plus/minus 0.1N, and a displacement resolution of 0.05 microns with a stability of plus/minus 0.1 microns. Samples of eutectic Sn-Ag solder were reflowed to develop the microstructure used in microelectronic packaging. Creep tests were conducted at various stresses and temperatures and showed that coarse microstructures creep more rapidly than the microstructures in the tested regime.

  13. Transected sciatic nerve repair by diode laser protein soldering.

    Science.gov (United States)

    Fekrazad, Reza; Mortezai, Omid; Pedram, MirSepehr; Kalhori, Katayoun Am; Joharchi, Khojasteh; Mansoori, Korosh; Ebrahimi, Roja; Mashhadiabbas, Fatemeh

    2017-08-01

    Despite advances in microsurgical techniques, repair of peripheral nerve injuries (PNI) is still a major challenge in regenerative medicine. The standard treatment for PNI includes suturing and anasthomosis of the transected nerve. The objective of this study was to compare neurorraphy (nerve repair) using standard suturingto diode laser protein soldering on the functional recovery of transected sciatic nerves. Thirty adult male Fischer-344 Wistar rats were randomly assigned to 3 groups: 1. The control group, no repair, 2. the standard of care suture group, and 3. The laser/protein solder group. For all three groups, the sciatic nerve was transected and the repair was done immediately. For the suture repair group, 10.0 prolene suture was used and for the laser/protein solder group a diode laser (500mW output power) in combination with bovine serum albumen and indocyanine green dye was used. Behavioral assessment by sciatic functional index was done on all rats biweekly. At 12weeks post-surgery, EMG recordings were done on all the rats and the rats were euthanized for histological evaluation of the sciatic nerves. The one-way ANOVA test was used for statistical analysis. The average time required to perform the surgery was significantly shorter for the laser-assisted nerve repair group compared to the suture group. The EMG evaluation revealed no difference between the two groups. Based on the sciatic function index the laser group was significantly better than the suture group after 12weeks (pneurorraphy using standard suturing methods. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Inductive Soldering of the Junctions of the Main Superconducting Busbars of the LHC

    CERN Document Server

    Jacquemod, A; Schauf, F; Skoczen, Blazej; Tock, J P

    2004-01-01

    The Large Hadron Collider (LHC) is the next world-facility for the high energy physics community, presently under construction at CERN, Geneva. The LHC will bring into collisions intense beams of protons and ions. The main components of the LHC are the twin-aperture high-field superconducting cryomagnets that will be installed in the existing 26.7-km long tunnel. They are powered in series by superconducting Nb-Ti cables. Along the machine, about 60 000 joints between superconducting cables must be realised in-situ during the installation. Ten thousands of them, rated at 13 000 A, are involved in the powering scheme of the main dipoles and quadrupoles. To meet the requirements of the cryogenic budget, an electrical resistance at operating temperature (1.9 K) lower than 0.6 nW has to be achieved. The induction soldering technology was selected for this purpose. After a brief introduction to the LHC project, the constraints and requirements are listed. Then, the applied solution is detailed. The splices of the ...

  15. In situ and Enriched Microbial Community Composition and Function Associated with Coal Bed Methane from Powder River Basin Coals

    Science.gov (United States)

    Barnhart, Elliott; Davis, Katherine; Varonka, Matthew; Orem, William; Fields, Matthew

    2016-04-01

    Coal bed methane (CBM) is a relatively clean source of energy but current CBM production techniques have not sustained long-term production or produced enough methane to remain economically practical with lower natural gas prices. Enhancement of the in situ microbial community that actively generates CBM with the addition of specific nutrients could potentially sustain development. CBM production more than doubled from native microbial populations from Powder River Basin (PRB) coal beds, when yeast extract and several individual components of yeast extract (proteins and amino acids) were added to laboratory microcosms. Microbial populations capable of hydrogenotrophic (hydrogen production/utilization) methanogenesis were detected in situ and under non-stimulated conditions. Stimulation with yeast extract caused a shift in the community to microorganisms capable of acetoclastic (acetate production/utilization) methanogenesis. Previous isotope analysis from CBM production wells indicated a similar microbial community shift as observed in stimulation experiments: hydrogenotrophic methanogenesis was found throughout the PRB, but acetoclastic methanogenesis dominated major recharge areas. In conjunction, a high proportion of cyanobacterial and algal SSU rRNA gene sequences were detected in a CBM well within a major recharge area, suggesting that these phototrophic organisms naturally stimulate methane production. In laboratory studies, adding phototrophic (algal) biomass stimulated CBM production by PRB microorganisms similarly to yeast extract (~40μg methane increase per gram of coal). Analysis of the British thermal unit (BTU) content of coal from long-term incubations indicated >99.5% of BTU content remained after CBM stimulation with either algae or yeast extract. Biomimicry of in situ algal CBM stimulation could lead to technologies that utilize coupled biological systems (photosynthesis and methane production) that sustainably enhance CBM production and generate

  16. Reliability of Wind Turbine Components-Solder Elements Fatigue Failure

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Sørensen, John Dalsgaard

    2012-01-01

    on the temperature mean and temperature range. Constant terms and model errors are estimated. The proposed methods are useful to predict damage values for solder joint in power electrical components. Based on the proposed methods it is described how to find the damage level for a given temperature loading profile....... The proposed methods are discussed for application in reliability assessment of Wind Turbine’s electrical components considering physical, model and measurement uncertainties. For further research it is proposed to evaluate damage criteria for electrical components due to the operational temperature...

  17. Pressure brazing of ceramics to metals with copper solder

    International Nuclear Information System (INIS)

    Pavlova, M.A.; Metelkin, I.I.

    1986-01-01

    The effect on the quality of joints brazed with copper of different non metallized aluminooxide dielectrics with metals and alloys of a series of technological parameters (temperature, pressure, holding, and medium) in the course of pressure brazing is investigated. It is shown that in case of brazing with kovar and nickel the character of dependences is identical, however in all cases the joints with nickel are more durable. For the ceramics - molybdenum system characterized by weak interaction with copper solder kinetic dependences have no maximum and only under holding of more than 20 min the constant strength of 150-190 MPa is attained

  18. Surface Properties of the IN SITU Formed Ceramics Reinforced Composite Coatings on TI-3AL-2V Alloys

    Science.gov (United States)

    Liu, Peng; Guo, Wei; Hu, Dakui; Luo, Hui; Zhang, Yuanbin

    2012-04-01

    The synthesis of hard composite coating on titanium alloy by laser cladding of Al/Fe/Ni+C/Si3N4 pre-placed powders has been investigated in detail. SEM result indicated that a composite coating with metallurgical joint to the substrate was formed. XRD result indicated that the composite coating mainly consisted of γ-(Fe, Ni), FeAl, Ti3Al, TiC, TiNi, TiC0.3N0.7, Ti2N, SiC, Ti5Si3 and TiNi. Compared with Ti-3Al-2V substrate, an improvement of the micro-hardness and the wear resistance was observed for this composite coating.

  19. In-situ reactions in hybrid aluminum alloy composites during incorporating silica sand in aluminum alloy melts

    Directory of Open Access Journals (Sweden)

    Benjamin F. Schultz

    2016-07-01

    Full Text Available In order to gain a better understanding of the reactions and strengthening behavior in cast aluminum alloy/silica composites synthesized by stir mixing, experiments were conducted to incorporate low cost foundry silica sand into aluminum composites with the use of Mg as a wetting agent. SEM and XRD results show the conversion of SiO2 to MgAl2O4 and some Al2O3 with an accompanying increase in matrix Si content. A three-stage reaction mechanism proposed to account for these changes indicates that properties can be controlled by controlling the base Alloy/SiO2/Mg chemistry and reaction times. Experimental data on changes of composite density with increasing reaction time and SiO2 content support the three-stage reaction model. The change in mechanical properties with composition and time is also described.

  20. Synthesis and characterization of tin and antimony based composites derived by mechanochemical in situ reduction of oxides

    International Nuclear Information System (INIS)

    Patel, P.; Roy, S.; Kim, I.L.-Seok; Kumta, P.N.

    2004-01-01

    Composites consisting of tin and silicon dioxide or antimony and silicon dioxide were synthesized using high energy mechanical milling. The composites were made by the reactive milling of SnO or Sb 2 O 3 with pure Si, resulting in the oxidation of silicon and the reduction of the metal oxides. The minimum time required to complete the reaction for the tin system was 170 min, while the minimum time for the antimony system was 230 min. X-ray diffraction and infrared spectroscopy were used to determine the phases present in the composites. In addition, scanning electron microscopy, along with energy dispersive X-ray analysis (EDX), was used to characterize the microstructure and composition of the resultant material