WorldWideScience

Sample records for brazing refractory metals

  1. Binary alloys for refractory-metal brazing

    Science.gov (United States)

    Morris, J. F.

    1974-01-01

    Data on binary-metal eutectics and melting-point minimums have been assembled for use in selecting brazing filler compositions for refractory metals. Data are presented in four tables for ready reference. Brief discussion of problems and potentials of metallides is included in appendix.

  2. Refractory metals welded or brazed with tungsten inert gas equipment

    Science.gov (United States)

    Wisner, J. P.

    1965-01-01

    Appropriate brazing metals and temperatures facilitate the welding or brazing of base metals with tungsten inert gas equipment. The highest quality bond is obtained when TIG welding is performed in an inert atmosphere.

  3. Some possible filler alloys with low vapor pressures for refractory-metal brazing

    Science.gov (United States)

    Morris, J. F.

    1973-01-01

    A compilation of eutectics and melting-point minima for binary combinations of metals having vapor pressures below 10 to the minus 10th power torr at 1500 degrees K and .00005 torr at 2000 degree K is presented. These compositions and others near them on their phase diagrams are potential special brazing fillers for refractory metals. Some possible problems and advantages for fusion bonds of such mixtures are indicated. Evaluations of brazing fillers containing refractory metals are reported.

  4. Brazing Dissimilar Metals

    Science.gov (United States)

    Krotz, Phillip D.; Davis, William M.; Wisner, Daniel L.

    1996-01-01

    Brazing effective technique for joining ordinary structural metals to brittle, low-thermal-expansion refractory metals. Specifically, brazing process established for joining copper or nickel flanges to ends of vacuum-plasma-sprayed tungsten tubes and for joining stainless-steel flanges to ends of tubes made of alloy of molybdenum with 40 percent of rhenium.

  5. Fabrication and Characterization of Brazed Joints for SiC-Metallic Systems Utilizing Refractory Metals

    Science.gov (United States)

    Coddington, Bryan; Asthana, Rajiv; Halbig, Michael C.; Singh, M.

    2011-01-01

    Metal to ceramic joining plays a key role for the integration of ceramics into many nuclear, ground and aero based technologies. In order to facilitate these technologies, the active metal brazing of silicon carbide (CVD beta-SiC, 1.1 mm thick, and hot-pressed alpha-SiC, 3 mm thick) to the refractory metals molybdenum and tungsten using active braze alloys was studied. The joint microstructure, composition, and microhardness were evaluated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Knoop hardness testing. The braze alloys, Cusil-ABA, Ticusil and Copper-ABA, all formed sound joints with excellent wetting and chemical bonding with the SiC substrate. Despite the close thermal expansion match between the metal substrates and SiC, hairline cracks formed in alpha-SiC while beta-SiC showed no signs of residual stress cracking. The use of ductile interlayers to reduce the effect from residual stresses was investigated and joints formed with copper as an interlayer produced crack free systems utilizing both CVD and hot-pressed SiC.

  6. Direct metal brazing to cermet feedthroughs

    Science.gov (United States)

    Not Available

    1982-07-29

    An improved method for brazing metallic components to a cermet surface in an alumina substrate eliminates the prior art metallized layer over the cermet via and adjoining alumina surfaces. Instead, a nickel layer is applied over the cermet surface only and metallic components are brazed directly to this nickel coated cermet surface. As a result, heretofore unachievable tensile strength joints are produced. In addition, cermet vias with their brazed metal components can be spaced more closely in the alumina substrate because of the elimination of the prior art metallized alumina surfaces.

  7. BRAZING ALLOYS

    Science.gov (United States)

    Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

    1962-02-20

    A brazing alloy is described which, in the molten state, is characterized by excellent wettability and flowability and is capable of forming a corrosion-resistant brazed joint. At least one component of said joint is graphite and the other component is a corrosion-resistant refractory metal. The brazing alloy consists essentially of 40 to 90 wt % of gold, 5 to 35 wt% of nickel, and 1 to 45 wt% of tantalum. (AEC)

  8. Method for brazing together planar and nonplanar metal members

    Science.gov (United States)

    Hammersand, Fred G.; Witkowski, Anthony J.

    1985-01-01

    The invention relates to a method and apparatus for brazing two metal members together, at least one of which is nonplanar, in a brazing furnace using a substantially pure brazing material. The method comprises the steps of utilizing a brazing fixture to hold the two metal members in tangential relation to one another along a portion of each member so that a cavity is formed adjacent to the contacting portions. A braze material is then positioned within the cavity. The braze fixture, the metal members, and the braze material are then placed in a brazing furnace. A heat shield is then placed over the braze fixture, the metal members, and the braze material to shield the braze material from direct furnace radiation. The furnace temperature is linearly increased at a rate of about 180.degree. C. per hour until a temperature of 350.degree. C. is achieved. Heat is transferred by conduction from the metal members to the braze material to cause the braze material to melt. Some material from the metal members slowly diffuses into the braze material forming a braze joint. The furnace is rapidly cooled to room temperature using nitrogen gas. The brazed assemblies made according to this method are superior to assemblies formed by heliarc welding.

  9. Corrosion Behavior of Brazed Zinc-Coated Structured Sheet Metal

    Directory of Open Access Journals (Sweden)

    A. Nikitin

    2017-01-01

    Full Text Available Arc brazing has, in comparison to arc welding, the advantage of less heat input while joining galvanized sheet metals. The evaporation of zinc is reduced in the areas adjacent to the joint and improved corrosion protection is achieved. In the automotive industry, lightweight design is a key technology against the background of the weight and environment protection. Structured sheet metals have higher stiffness compared to typical automobile sheet metals and therefore they can play an important role in lightweight structures. In the present paper, three arc brazing variants of galvanized structured sheet metals were validated in terms of the corrosion behavior. The standard gas metal arc brazing, the pulsed arc brazing, and the cold metal transfer (CMT® in combination with a pulsed cycle were investigated. In experimental climate change tests, the influence of the brazing processes on the corrosion behavior of galvanized structured sheet metals was investigated. After that, the corrosion behavior of brazed structured and flat sheet metals was compared. Because of the selected lap joint, the valuation of damage between sheet metals was conducted. The pulsed CMT brazing has been derived from the results as the best brazing method for the joining process of galvanized structured sheet metals.

  10. Metal substrate effects on the thermochemistry of active brazing interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Arroyave, Raymundo; Eagar, Thomas W

    2003-09-15

    This work investigates the effects of the metal substrate on the thermochemistry of active brazing alloys during ceramic/metal joining applications. The thermodynamics and kinetics of the interactions between the metal substrate and the braze alloy are examined. Numerical simulations are used to rationalize experimental observations reported elsewhere. It is shown that using Ni metal substrates at temperatures much higher than the liquidus of the brazing alloys can dramatically decrease the chemical activity of Ti in Cu-based brazing alloys. This effect is much less intense when Fe-metal substrates are in contact with the same active brazing alloy systems. It is additionally proven that the time scales necessary to observe such detrimental decrease in chemical activity are on the order of minutes.

  11. Brazing

    CERN Document Server

    Schwartz, Mel M

    2003-01-01

    Text provides information needed to braze materials that will be used in the 21st century. Revised to include lessons learned on tooling, design, materials, atmospheres, processing, and equipment. For brazing technologists and engineers.

  12. Thermochemistry of brazing ceramics and metals in air

    Energy Technology Data Exchange (ETDEWEB)

    Bobzin, Kirsten; Schlaefer, Thomas; Kopp, Nils [RWTH Aachen (DE). Surface Engineering Inst. (IOT)

    2011-08-15

    Reactive air brazing offers economically and technologically advantageous joining of ceramics to metals. Solid oxide fuel cells and membranes for oxyfuel combustion are recent fields of application. However, it remains a problem that strong metallurgical reactions between brazes and base materials occur. These reactions were analysed by differential scanning calorimetry tests to get a better understanding. Therefore, three braze alloys (Ag8Cu, Ag8Cu0.5Ti and Ag4Cu4Ni) and five base materials (alumina, 3YSZ partially stabilised zirconia, BSCF perovskite ceramic, X1CrTi-La22 and X15CrNiSi25-20) were investigated. The reaction peaks correlate with the formation of reaction layers, which were observed in metallographic analysis of brazed specimens. The results help to explain the reaction mechanisms and allow optimised selection of filler metals and brazing temperature. (orig.)

  13. Active Metal Brazing and Characterization of Brazed Joints in Titanium to Carbon-Carbon Composites

    Science.gov (United States)

    Singh, M.; Shpargel, T. P.; Morscher, G. N.; Asthana, R.

    2006-01-01

    The Ti-metal/C-C composite joints were formed by reactive brazing with three commercial brazes, namely, Cu-ABA, TiCuNi, and TiCuSiI. The joint microstructures were examined using optical microscopy and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). The results of the microstructure analysis indicate solute redistribution across the joint and possible metallurgical bond formation via interdiffusion, which led to good wetting and spreading. A tube-on-plate tensile test was used to evaluate joint strength of Ti-tube/ C-C composite joints. The load-carrying ability was greatest for the Cu-ABA braze joint structures. This system appeared to have the best braze spreading which resulted in a larger braze/C-C composite bonded area compared to the other two braze materials. Also, joint loadcarrying ability was found to be higher for joint structures where the fiber tows in the outer ply of the C-C composite were aligned perpendicular to the tube axis when compared to the case where fiber tows were aligned parallel to the tube axis.

  14. Brazing handbook

    CERN Document Server

    American Welding Society

    2007-01-01

    By agreement between the American Welding Society C3 Committee on Brazing and Soldering and the ASM Handbook Committee, the AWS Brazing Handbook has been formally adopted as part of the ASM Handbook Series. Through this agreement, the brazing content in the ASM Handbook is significantly updated and expanded. The AWS Brazing Handbook, 5th Edition provides a comprehensive, organized survey of the basics of brazing, processes, and applications. Addresses the fundamentals of brazing, brazement design, brazing filler metals and fluxes, safety and health, and many other topics. Includes new chapters on induction brazing and diamond brazing.

  15. Laser Brazing metallic embedding technique for fiber optic sensors

    Science.gov (United States)

    Grandal, Tania; Fraga, Sergio; Castro, Gemma; Vazquez, Esteban; Zornoza, Ander

    2017-04-01

    In this paper a fiber optic metallic embedding technique is presented based on laser Brazing manufacturing process. The embedding strategy to follow by the laser Brazing, which consists in three steps, minimizes the thermal stress of the embedded fiber, relaxes microbending strains and reduces damage on the fiber. The minimum embedded fiber optic Ni coating total diameter is 237 μm for a successful process with negligible optical loss on the fiber. Fiber Bragg Gratings were successfully embedded in metallic specimens and their strain response was in accordance with their specifications.

  16. Brazing diamond grits onto a steel substrate using copper alloys as the filler metals

    Science.gov (United States)

    Chen, S.-M.; Lin, S.-T.

    1996-12-01

    Surface-set diamond tools were fabricated by an active metal brazing process, using bronze (Cu-8.9Sn) powder and 316L stainless steel powder mixed to various ratios as the braze filler metals. The diamond grits were brazed onto a steel substrate at 1050 °C for 30 min in a dry hydrogen atmosphere. After brazing practice, an intermediate layer rich in chromium formed between the braze filler metal and diamond. A braze filler metal composed of 70 wt % bronze powder and 30 wt % stainless steel powder was found to be optimum in that the diamond grits were strongly impregnated in the filler metal by both mechanical and chemical types of holding. The diamond tools thus fabricated performed better than conventional nickel-plated diamond tools. In service, the braze filler metal wore at almost the same rate as the diamond grits, and no pullout of diamond grits or peeling of the filler metal layer took place.

  17. Substrate Effects on the High Temperature Oxidation Behavior of a Gold-Based Braze Filler Metal

    Energy Technology Data Exchange (ETDEWEB)

    Weil, K. Scott; Rice, Joseph P.

    2005-06-30

    Oxidation testing was conducted on a commercial gold-based braze alloy, Gold ABA, and on zirconia and stainless steel joining couples prepared using this braze filler metal. Preliminary results reveal that both substrates play a significant role in determining the overall oxidation resistance of the brazed joint.

  18. Study on a novel Sn-electroplated silver brazing filler metal

    Science.gov (United States)

    Wang, Xingxing; Peng, Jin; Cui, Datian

    2017-08-01

    Novel Sn-electroplated Ag brazing filler metal with a high tin content was prepared by combining the plating and thermal diffusion method. The BAg45CuZn alloy was used as a base filler metal, and a Sn layer was electroplated on it. Then the H62 brass was brazed with the Sn-plated brazing filler metal containing 6.2 wt% of Sn. The results showed that the microstructure of the brazed joints with the Sn-plated filler mainly consisted of the Ag phase, Cu phase, CuZn phase and Cu5Zn8 phase. The tensile strength of the joints brazed with the Sn-plated filler metal was 326 MPa, which was higher than that of the joints with the base filler metal. Fracture analysis showed that the fractures of the joints brazed by the Sn-plated filler metal was mainly ductile fracture mixed with a small quantity of brittle fracture.

  19. Brazing SiC/SiC Composites to Metals

    Science.gov (United States)

    Steffier, Wayne S.

    2004-01-01

    Experiments have shown that active brazing alloys (ABAs) can be used to join SiC/SiC composite materials to metals, with bond strengths sufficient for some structural applications. The SiC/SiC composite coupons used in the experiments were made from polymerbased SiC fiber preforms that were chemical-vapor-infiltrated with SiC to form SiC matrices. Some of the metal coupons used in the experiments were made from 304 stainless steel; others were made from oxygen-free, high-conductivity copper. Three ABAs were chosen for the experiments: two were chosen randomly from among a number of ABAs that were on hand at the time; the third ABA was chosen because its titanium content (1.25 percent) is less than those of the other two ABAs (1.75 and 4.5 percent, respectively) and it was desired to evaluate the effect of reducing the titanium content, as described below. The characteristics of ABAs that are considered to be beneficial for the purpose of joining SiC/SiC to metal include wettability, reactivity, and adhesion to SiC-based ceramics. Prior to further development, it was verified that the three chosen ABAs have these characteristics. For each ABA, suitable vacuum brazing process conditions were established empirically by producing a series of (SiC/SiC)/ABA wetting samples. These samples were then sectioned and subjected to scanning electron microscopy (SEM) and energy-dispersive x-ray spectrometry (EDS) for analysis of their microstructures and compositions. Specimens for destructive mechanical tests were fabricated by brazing of lap joints between SiC/SiC coupons 1/8-in. (.3.2- mm) thick and, variously, stainless steel or copper tabs. The results of destructive mechanical tests and the SEM/EDS analysis were used to guide the development of a viable method of brazing the affected materials.

  20. The constitutive response of brazing alloys and the residual stresses in ceramic-metal joints

    OpenAIRE

    Galli, Matteo

    2007-01-01

    Nowadays the joining of dissimilar materials is often the only solution to fulfill the complex requirements of high technology applications. One of the fields in which the research activity is more intense and promising is that of the brazing of ceramics with metals. The performance of brazed ceramic-metal joints is limited by residual stresses which develop in the bonded assembly as it cools down after brazing. The magnitude and influence of these stresses can be particularly high because of...

  1. Reversible brazing process

    Science.gov (United States)

    Pierce, Jim D.; Stephens, John J.; Walker, Charles A.

    1999-01-01

    A method of reversibly brazing surfaces together. An interface is affixed to each surface. The interfaces can be affixed by processes such as mechanical joining, welding, or brazing. The two interfaces are then brazed together using a brazing process that does not defeat the surface to interface joint. Interfaces of materials such as Ni-200 can be affixed to metallic surfaces by welding or by brazing with a first braze alloy. The Ni-200 interfaces can then be brazed together using a second braze alloy. The second braze alloy can be chosen so that it minimally alters the properties of the interfaces to allow multiple braze, heat and disassemble, rebraze cycles.

  2. Large Area Active Brazing of Multi-tile Ceramic-Metal Structures

    Science.gov (United States)

    2012-05-01

    Large Area Active Brazing of Multi-tile Ceramic-Metal Structures by Kevin J. Doherty ARL-RP-366 May 2012 A...reprint from the Proceedings From the 5th International Brazing and Soldering Conference, Las Vegas, NV, 22–25 April 2012...Army Research Laboratory Aberdeen Proving Ground, MD 21005-5069 ARL-RP-366 May 2012 Large Area Active Brazing of Multi-tile

  3. The Microstructural Evolution of Vacuum Brazed 1Cr18Ni9Ti Using Various Filler Metals

    Directory of Open Access Journals (Sweden)

    Yunxia Chen

    2017-04-01

    Full Text Available The microstructures and weldability of a brazed joint of 1Cr18Ni9Ti austenitic stainless steel with BNi-2, BNi82CrSiBFe and BMn50NiCuCrCo filler metals in vacuum were investigated. It can be observed that an interdiffusion region existed between the filler metal and the base metal for the brazed joint of Ni-based filler metals. The width of the interdiffusion region was about 10 μm, and the microstructure of the brazed joint of BNi-2 filler metal was dense and free of obvious defects. In the case of the brazed joint of BMn50NiCuCrCo filler metal, there were pits, pores and crack defects in the brazing joint due to insufficient wettability of the filler metal. Crack defects can also be observed in the brazed joint of BNi82CrSiBFe filler metal. Compared with BMn50NiCuCrCo and BNi82CrSiBFe filler metals, BNi-2 filler metal is the best material for 1Cr18Ni9Ti austenitic stainless steel vacuum brazing because of its distinct weldability.

  4. Substrate Effects on the High Temperature Oxidation Behavior of a Gold-Based Braze Filler Metal

    Energy Technology Data Exchange (ETDEWEB)

    Weil, K. Scott; Rice, Joseph P.

    2005-06-01

    Oxidation testing was conducted on a commercial gold-based braze alloy, Gold ABA®, and on zirconia/stainless steel couples joined using this filler metal. Preliminary results reveal that both substrates play a significant role in determining the overall oxidation behavior of the brazed joint.

  5. The influence of metallic brazing materials on the strain formation of internally water-cooled X-ray optics.

    Science.gov (United States)

    Oberta, P; Kittler, M; Áč, V; Hrdý, J; Iragashi, N; Scheinost, A C; Uchida, Y

    2015-03-01

    A study of metallic brazing material for internally cooled optics is presented. The study shows the influence of the different material properties on the final quality of the bond in terms of diffracted wavefront distortion, i.e. enlargement of the rocking curve. By choosing the proper brazing material and applying the proper brazing conditions, the influence of the brazing material can be fully eliminated. Furthermore the degradation of some brazing material due to the extreme working conditions of the optics is presented. Measurement results from ESRF and KEK confirm the importance of the proper brazing material choice.

  6. Development of Pd-Ni Brazing Filler Metals for SUS316L Stainless Steel

    OpenAIRE

    Hiroshi, IZUI; Yoshifumi, SUEZAWA; College of Science and Technology, Nihon Univ.

    1993-01-01

    Several braze alloys containing palladium have been newly developed for use in high temperature brazing of stainless steel SUS 316 L. Palladium filler metals have excellent high-temperature strength, corrosion and oxidation resistance, ductility, and relatively high melting points and are of lower cost than gold-based filler metals. In this research, two types of palladium-containing brazing filler metals were considered, 40 Pd-50 Ni-10 Co and 30 Pd-50 Ni-10 Cu-10 Co (all in wt-%). Commercial...

  7. Reduction of liquid metal embrittlement in copper-brazed stainless steel joints

    Science.gov (United States)

    Uhlig, T.; Fedorov, V.; Elßner, M.; Wagner, G.; Weis, S.

    2017-03-01

    Due to its very good formability and the low raw material cost, pure copper in form of foils is commonly used to braze plate heat exchangers made of stainless steel. The difference in the electrochemical potentials of brazing filler and base material leads to corrosion effects in contact with electrolytes. This may lead to leakages, which decrease the reliability of the heat exchanger during service in potable water. The dissolution of the emerging corrosion products of brazing filler and base material induces the migration of heavy metal ions, such as Cu2+ and Ni2+, into the potable water. The so-called liquid metal embrittlement, which takes place during the brazing process, may intensify the corrosion. The brazing filler infiltrates the stainless steel along the grain boundaries and causes an embrittlement. This paper deals with the determination of the grain boundary erosion dependent on the degree of deformation and heat treatment of the stainless steel AISI 316L.

  8. Residual Stress and Bonding Strength in the ElectricalSialon Ceramics Joint Made by Using the Brazing Metal Layer

    OpenAIRE

    Kimura, Mitsuhiko; Asari, Koichi; Goto, Shoji; Aso, Setsuo

    2002-01-01

    Electrical Sialons which have some TiN contents were joined with Ag-Cu-Ti active brazing metal layer having a thickness from 30μm to 400μm at a temperature from 1113 K to 1213 K in a vacuum. Residual stress in the brazed joint specimens was not observed when the thickness of brazing metal layer was 30 μ m. However, the residual stress of 80 MPa was detected when the thickness of brazing metal layer increased up to 400μm. When the brazing temperature was 1113 K, four-point bending strengths of...

  9. Cleaning Effect of Interlayer Metal on the Joining Surface during Braze Pressure Welding

    National Research Council Canada - National Science Library

    INAGAKI, Yohei; SUZUMURA, Akio; IKESHOJI, Toshi-Taka; YAMAZAKI, Takahisa

    2005-01-01

    Braze Pressure Welding (BPW) with high frequency induction heating is a newly developed pressure welding technique using interlayer metals for welding the general steel pipes for pipe arrangement in buildings...

  10. Vacuum Brazing Diamond Grits with Cu-based or Ni-based Filler Metal

    Science.gov (United States)

    Qi, Wenchun; Lu, Jinbin; Li, Yang; Xu, Shuai; Zhong, Sujuan; Wang, Bangfu; Qiu, Xinkai

    2017-08-01

    Diamond grits were brazed using Cu-Sn-Cr and Ni-Cr-B-Si filler metals, and the brazed grits were examined for microstructure (SEM, EDS, XRD), microhardness, and compression strength. Results showed that the microstructure of the Cu-based filler metal was uniform and consisted of α-Cu + (α-Cu + δ). Its wettability to the diamond was better than Ni-based filler due to the formation of a thin carbide reaction layer that improved the bond strength between the diamond and steel. The Cu-based filler led to reduced thermal damage to the diamond. The Cr in the filler metal diffused to the steel substrate to form a reaction layer at the filler/steel substrate interface. The microhardness of the Ni filler metal (810-830 HV0.3) was significantly higher than that of Cu filler metal (170-230 HV0.3). The compressive load values of the diamond grits brazed with Cu-based or Ni-based filler metal were 93.7 and 49.2% of the original diamond, and the TI values were 83.7 and 59.8% of the original diamond. Grinding experiments for failure mode in monolayer tools revealed that the tools brazed with Cu-based filler metal had a lower macro-fracture ratio than those brazed using the Ni-based filler.

  11. Evaluation of the adhesion strength of diamond films brazed on K-10 type hard metal

    Directory of Open Access Journals (Sweden)

    Sérgio Ivan dos Santos

    2004-06-01

    Full Text Available The coating of cutting tools with diamond films considerably increases the tool performance due to the combination of the unique tribological properties of diamond with the bulk properties of the substrate (toughness. The tool performance, however, is strongly related to the adhesion strength between the film and the substrate. In this work our main goal was to propose and to test a procedure, based on a tensile strength test, to evaluate the adhesion strength of a diamond wafer brazed on a hard metal substrate, taking into account the effect of the brazing temperature and time. The temperature range studied was from 800 to 980 °C and the brazing time ranged from 3 to 40 min. The obtained results could be used to optimize the costs and time required to the production of high performance cutting tools with brazed diamond wafers.

  12. Cleaning Effect of Interlayer Metal on the Joining Surface during Braze Pressure Welding

    Science.gov (United States)

    Inagaki, Yohei; Suzumura, Akio; Ikeshoji, Toshi-Taka; Yamazaki, Takahisa

    Braze Pressure Welding (BPW) with high frequency induction heating is a newly developed pressure welding technique using interlayer metals for welding the general steel pipes for pipe arrangement in buildings. BPW enables to make joints by solid-state welding in air with relatively small deformation. In this method, the interlayer metal is expected to play the primary role in making high performance joints. It removes contaminations from the joining surface of the base metal and forms fillets at the gaps around the joint. It had been revealed by some experiments and/or numerical analyses in previous research that the BPW joint had higher tensile strength than the brazed joint, and that the fillet can improve the joint strength. In this study, in order to investigate the cleaning effect of interlayer metal more closely, a low carbon steel plate specimen was brazed mainly by Ni-based brazing filler using a tungsten spacer. The microscopy and EPMA analysis on the joints made by various brazing temperatures and durations confirmed that the oxide films on the joining surfaces were removed and discharged from the joining region by the interlayer metal.

  13. Improving contour accuracy and strength of reactive air brazed (RAB) ceramic/metal joints by controlling interface microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chichi; Kuhn, Bernd; Brandenberg, Joerg; Beck, Tilmann; Singheiser, Lorenz [Forschungszentrum Juelich GmbH, Institute for Energy and Climate Research (IEK), Microstructure and Properties of Materials (IEK-2), 52425 Juelich (Germany); Bobzin, Kirsten; Bagcivan, Nazlim; Kopp, Nils [Surface Engineering Institute (IOT), RWTH Aachen University, Kackertstr. 15, 52072 Aachen (Germany)

    2012-06-15

    The development of high-temperature electrochemical devices such as solid oxide fuel cells, oxygen, and hydrogen separators and gas reformers poses a great challenge in brazing technology of metal/ceramic joints. To maintain the integrity of such equipment, the resulting seals have to be stable and hermetic during continuous and cyclic high temperature operation. As a solution for joining metal and ceramic materials, reactive air brazing has gained increasing interest in recent years. This paper compares joints brazed by different filler alloys: pure Ag, AgCu, and AgAl in three different aspects: contour accuracy, room temperature delamination resistance, and corresponding microstructures of the as-brazed and fractured brazed joints. Discussion focuses on fracture mechanism and associated delamination resistance. AgAl brazed joints exhibit the most promising mechanical properties and contour accuracy. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Joining of molybdenum disilicide to stainless steel using amorphous metal brazes - residual stress analysis

    Energy Technology Data Exchange (ETDEWEB)

    Vaidya, R.U.; Gallegos, D.E.; Kautz, D.D. [Los Alamos National Lab. (United States)

    2007-07-01

    Molybdenum disilicide (MoSi{sub 2})/stainless steel 316 L joints were produced by high temperature brazing using a cobalt-based metallic-glass (METGLAS trademark 2714A). Successful joining was completed in two different ways; either by feeding excess braze into the braze gap upon heating or by constraining the MoSi{sub 2}/stainless steel assembly with an alumina (Al{sub 2}O{sub 3}) fixture during the heating cycle. These steps were necessary to ensure the production of a high quality void free joint. Residual stress measurements were completed on these joints. Indentation results show higher tensile residual stresses in the stainless steel for the joint with the external constraint, in comparison to the unconstrained state. In contrast, the compressive residual stresses in the MoSi{sub 2} (as measured by X-ray diffraction) were lower in the constrained state relative to the unconstrained state. These results and a lack of residual stress balance indicate that the stress state in the braze is significantly different under the two joining conditions and the volume of the braze plays an important role in the development of the residual stresses. Push-out tests carried out on these joints gave higher joint strengths in the unconstrained as compared to the constrained condition. The results of this study have important implications on the selection of the appropriate joining process (use of constraint versus extra braze). (orig.)

  15. Novel high chromium containing braze filler metals for heat exchanger applications

    Energy Technology Data Exchange (ETDEWEB)

    Rangaswamy, S.; Fortuna, D. [Sulzer Metco, Troy (United States)

    2007-07-01

    A new family of boron-free, high chromium containing braze filler metal compositions were developed (Amdry 105, Amdry 108, Amdry 805). Filler metal properties including metallurgical phases, melting range, flow, corrosion resistance and high temperature oxidation resistance are reported. Additionally, the technical and economical advantages of using these new filler metals in fabricating flat plate type of heat exchangers and metallic catalytic converters is discussed. (orig.)

  16. Microstructure and Mechanical Property of 3003 Aluminum Alloy Joint Brazed with Al-Si-Cu-Zn Filler Metal

    Directory of Open Access Journals (Sweden)

    LI Xiao-qiang

    2016-09-01

    Full Text Available Al-Si-Cu-Zn filler metal was developed to braze 3003 aluminum alloy. The microstructure and fracture surface of the joint were analyzed by XRD, SEM and EDS, and the effects of brazing temperature on microstructure and property of the joint were investigated. The results show that good joints are obtained at brazing temperature of 540-580℃ for 10min. The brazed joint consists of α(Al solid solution, θ(Al2Cu intermetallic compound, fine silicon phase and AlCuFeMn+Si phase in the central zone of brazed seam, and α(Al solid solution and element diffusion layers at both the sides of brazed seam, and the base metal. The room temperature (RT shear fracture of the joint occurs at the interface between the teeth shape α(Al in the diffusion layer and the center zone of brazed seam, which is mainly characterized as brittle cleavage. As the brazing temperature increases, α(Al solid solution crystals in the diffusion zone grow up, and the interfacial bonding of the joint is in the form of interdigitation. Brazing at 560℃ for 10min, the RT shear strength of the joint reaches the maximum value of 92.3MPa, which is about 62.7% of the base material.

  17. ZIRCONIUM-TITANIUM-BERYLLIUM BRAZING ALLOY

    Science.gov (United States)

    Gilliland, R.G.; Patriarca, P.; Slaughter, G.M.; Williams, L.C.

    1962-06-12

    A new and improved ternary alloy is described which is of particular utility in braze-bonding parts made of a refractory metal selected from Group IV, V, and VI of the periodic table and alloys containing said metal as a predominating alloying ingredient. The brazing alloy contains, by weight, 40 to 50 per cent zirconium, 40 to 50 per cent titanium, and the balance beryllium in amounts ranging from 1 to 20 per cent, said alloy having a melting point in the range 950 to 1400 deg C. (AEC)

  18. Active Metal Brazing and Characterization of Brazed Joints in C-C and C-SiC Composites to Copper-Clad-Molybdenum System

    Science.gov (United States)

    Singh, M.; Asthana, R.

    2008-01-01

    Carbon/carbon composites with CVI and resin-derived matrices, and C/SiC composites reinforced with T-300 carbon fibers in a CVI SiC matrix were joined to Cu-clad Mo using two Ag-Cu braze alloys, Cusil-ABA (1.75% Ti) and Ticusil (4.5% Ti). The brazed joints revealed good interfacial bonding, preferential precipitation of Ti at the composite/braze interface, and a tendency toward delamination in resin-derived C/C composite. Extensive braze penetration of the inter-fiber channels in the CVI C/C composites was observed. The Knoop microhardness (HK) distribution across the C/C joints indicated sharp gradients at the interface, and a higher hardness in Ticusil than in Cusil-ABA. For the C/SiC composite to Cu-clad-Mo joints, the effect of composite surface preparation revealed that ground samples did not crack whereas unground samples cracked. Calculated strain energy in brazed joints in both systems is comparable to the strain energy in a number of other ceramic/metal systems. Theoretical predictions of the effective thermal resistance suggest that such joined systems may be promising for thermal management applications.

  19. Microstructure and Properties of W-Cu Composite/Fe-Based Powder Alloy Vacuum Brazed Joint with Different Filler Metals

    Science.gov (United States)

    Xia, C. Z.; Yang, J.; Xu, X. P.; Zou, J. S.

    2017-05-01

    W-Cu composite and Fe-based powder alloy were brazed with filler metals of Ag-Cu and Cu-Mn-Co alloys in a vacuum furnace. Both of filler metals can join W-Cu composite with Fe-based powder alloy directly in the experiment process. Microstructure, distribution of elements and fracture morphology were observed and analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) methods, and phase composition of bonding area was analyzed by X-ray diffraction (XRD). The obtained results indicated that the smooth faying surface and dense microstructure of brazed joint were formed and the primary microstructure of brazing seam were, respectively, Ag(Cu) solid solution and Cu(Mn) solid solution, which ensured forming the stable connection of brazed joint. The bending strength of Ag-based and Cu-based brazed joint can, respectively, reach to 317 and 704 MPa, where fracture showed a typical ductile fracture characteristic. The fracture of Cu-based brazed joint located at brazing seam area, and the fracture of Ag-based brazed joint occurred in Fe-based powder alloy side.

  20. High temperature silver-palladium-copper oxide air braze filler metal

    Science.gov (United States)

    Darsell, Jens Tommy

    The Ag-CuO system is currently being investigated as the basis for an air braze filler metal alloy to be used in SOFC components. The system is of interest because unlike most braze alloys, it is capable of wetting a variety of ceramic materials while being applied in an air. This thesis work examined modification of Ag-CuO filler metal system by alloying with palladium to increase the use temperature of the resulting air braze alloy. Thermal analysis was performed to track changes in the solidus and liquidus temperatures for these alloys and determine equilibrium phase present as a function of temperature and composition. Sessile drop experiments were performed to investigate the effect of palladium addition on braze wetability. The influence of copper-oxide and palladium contents on brazed joint strength was characterized by a combination of four-point bend testing and fractography. From combined thermal analysis and quenched data it was found that both the liquidus and solidus increase with increasing palladium content, and the silver-rich miscibility gap boundary could be shifted by the addition of palladium. This was employed as a tool to study the effects of two-liquid phase formation on wetting behavior. In addition, a mass loss likely attributable to silver volatilization is observed in the Pd-modified filler metals when heated over ˜1100°C. As volatilization should be avoided, the ternary alloys should be limited to 15mol% Pd. It was found by sessile drop wetting experiments that there is a definitive change in wetting behavior that corresponds directly to the miscibility gap boundary for the Pd-Ag-CuO system. The first order transition tracks with changes in the miscibility gap boundary that can be induced by increasing palladium content. This is the first experimental evidence of critical point wetting behavior reported for a metal-oxide system and further confirms that critical point wetting theory is universal. Four-point bend testing and

  1. Brazing joints of gold alloy used in porcelain-fused-to-metal restorations and their resistance to deflection fatigue.

    Science.gov (United States)

    Vallittu, P K

    1997-06-01

    The aim of this study was to compare the resistance to deflection fatigue of a gold alloy used in porcelain-fused-to-metal restorations with and without a brazing joint. Pre-ceramic brazing filler metal was used to join the parent specimens of gold alloy together. The deflection fatigue test was carried out mainly with 0.4 m deflection of the test specimens (n = 5) but to obtain an S-N curve for the specimens, other magnitudes of deflection, i.e. the stress, were also used. When the fracture surface of the test specimens was examined by scanning electron microscopy (SEM), the results showed that the brazing joint in the gold alloy test specimen decreases the fatigue resistance considerably compared to that of specimens without a brazing joint (P = 0.002). SEM examination showed that the failure type of the brazing joint was cohesive and that the brazing filler metal had a more porous structure than the parent gold alloy. These results suggest that, due to the occlusal biting forces in situ, the brazing joints in fixed partial dentures can be fractured by metal fatigue.

  2. Refractory metal particles in refractory inclusions in the Allende meteorite

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, L. H.; Blander, M.

    1980-01-01

    An examination of refractory metal particles in five calcium-aluminum-rich inclusions in the Allende meteorite indicates a complex variety of compositions and large departures from equilibrium. These particles appear to have been primordial condensates which were isolated from the nebula and from each other at different times by cocondensing oxides. Selective diffusion and/or oxidation of the more oxidizable metals (Mo, W, Fe and Ni), phase segregations into different alloy phases (fcc, bcc, hcp and perhaps ordered phases) and the formation of metastable condensates appears to have been involved in the modification of these materials to their present state. Only a small fraction of our observations cannot be reconciled with this picture because of a lack of knowledge of some of the phase equilibria which might have bee involved.

  3. Brazing of Be with CuCrZr-bronze using copper-based filler metal STEMET

    Directory of Open Access Journals (Sweden)

    B.A. Kalin

    2016-12-01

    Optimization of the composition of the Cu–Ni–Sn–P system filler metals and comparative tests of filler metals of various compositions have been carried out in this paper to reduce the brazing temperature of beryllium with CuCrZr. Alloys of the following compositions Cu–6.4Ni–9.2Sn–6.3P (STEMET 1105 and Cu–9.1Ni–3.6Sn–8.0P (STEMET 1101 were made in the form of rapidly quenched ribbons with a thickness of 50µm and a width of 50mm. They were used to perform furnace brazing by Joule heating (with a rate of 15K/min of beryllium with CuCrZr (Be/CuCrZr at temperatures of 650, 700 and 750°C for 15min. Metallographic investigations of the zone of brazing and mechanical shear tests of joints before and after the heat treatment at 350°C for 30h have been conducted. It was found that the joints of Be/CuCrZr brazed at 650°C using STEMET 1105 (τs=230MPa and at 750°C using STEMET 1101 (τs=260MPa had the best shear strength properties. However, there is a significant decrease of the microhardness of CuCrZr from 1570 to 1140MPa at 750°C, which indicates a significant loss of its strength. The results obtained suggest that the brazing of beryllium with CuCrZr using STEMET 1105 at 650–700°C will not adversely affect the CuCrZr.

  4. Active vacuum brazing of CNT films to metal substrates for superior electron field emission performance.

    Science.gov (United States)

    Longtin, Rémi; Ramon Sanchez-Valencia, Juan; Shorubalko, Ivan; Furrer, Roman; Hack, Erwin; Elsener, Hansrudolf; Gröning, Oliver; Greenwood, Paul; Rupesinghe, Nalin; Teo, Kenneth; Leinenbach, Christian; Gröning, Pierangelo

    2015-02-01

    The joining of macroscopic films of vertically aligned multiwalled carbon nanotubes (CNTs) to titanium substrates is demonstrated by active vacuum brazing at 820 °C with a Ag-Cu-Ti alloy and at 880 °C with a Cu-Sn-Ti-Zr alloy. The brazing methodology was elaborated in order to enable the production of highly electrically and thermally conductive CNT/metal substrate contacts. The interfacial electrical resistances of the joints were measured to be as low as 0.35 Ω. The improved interfacial transport properties in the brazed films lead to superior electron field-emission properties when compared to the as-grown films. An emission current of 150 μA was drawn from the brazed nanotubes at an applied electric field of 0.6 V μm-1. The improvement in electron field-emission is mainly attributed to the reduction of the contact resistance between the nanotubes and the substrate. The joints have high re-melting temperatures up to the solidus temperatures of the alloys; far greater than what is achievable with standard solders, thus expanding the application potential of CNT films to high-current and high-power applications where substantial frictional or resistive heating is expected.

  5. A comparison of brazed metal and epoxied fibre Bragg grating strain sensors under high strain regimes

    Science.gov (United States)

    Mckeeman, I.; Niewczas, P.; Khan, S.

    2017-04-01

    Three different fibre Bragg grating strain sensors were tested for their suitability for measuring high strain. The sensor types were: a bare epoxied fibre Bragg grating, a standard fibre Bragg grating epoxied into a metal capillary and, finally, a metal coated fibre Bragg grating brazed into a metal capillary. The sensors were calibrated on a steel specimen up to 1400MPa (equivalent to 7.3mɛ). The results show that the bare epoxied Bragg grating and the metal packaged grating are suitable for measuring strains of this level.

  6. Furnace brazing under partial vacuum

    Science.gov (United States)

    Mckown, R. D.

    1979-01-01

    Brazing furnace utilizing partial-vacuum technique reduces tooling requirements and produces better bond. Benefit in that partial vacuum helps to dissociate metal oxides that inhibit metal flow and eliminates heavy tooling required to hold parts together during brazing.

  7. Barrier Coatings for Refractory Metals and Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    SM Sabol; BT Randall; JD Edington; CJ Larkin; BJ Close

    2006-02-23

    In the closed working fluid loop of the proposed Prometheus space nuclear power plant (SNPP), there is the potential for reaction of core and plant structural materials with gas phase impurities and gas phase transport of interstitial elements between superalloy and refractory metal alloy components during service. Primary concerns are surface oxidation, interstitial embrittlement of refractory metals and decarburization of superalloys. In parallel with kinetic investigations, this letter evaluates the ability of potential coatings to prevent or impede communication between reactor and plant components. Key coating requirements are identified and current technology coating materials are reviewed relative to these requirements. Candidate coatings are identified for future evaluation based on current knowledge of design parameters and anticipated environment. Coatings were identified for superalloys and refractory metals to provide diffusion barriers to interstitial transport and act as reactive barriers to potential oxidation. Due to their high stability at low oxygen potential, alumina formers are most promising for oxidation protection given the anticipated coolant gas chemistry. A sublayer of iridium is recommended to provide inherent diffusion resistance to interstitials. Based on specific base metal selection, a thin film substrate--coating interdiffusion barrier layer may be necessary to meet mission life.

  8. Induction Brazing

    DEFF Research Database (Denmark)

    Henningsen, Poul

    Induction brazing is a fast and appropriate method for industrial joining of complex geometries and metal combinations. In all types of brazing processes it is important to heat the joint interface of the two materials to the same, high temperature. If one of the specimens is warmer than the other...... materials has large influence on the heating time and temperature distribution in induction heating. In order to ensure high and uniform temperature distribution near the interface of a joint between dissimilar materials the precise coil geometry and position is of great importance. The present report...... presents a combined numerical and experimental method for determination of appropriate/optimiged coil geometry and position in induction brazing tube-to-plate joints of different ratios between tube and plate thickness and different combinations of the materials stainless steel, brass and copper...

  9. Brazing technique

    Science.gov (United States)

    Harast, Donald G.

    1986-01-01

    A method of brazing comprises sand blasting the surfaces of the components to be brazed with particles of a brazing material to clean the surfaces and to embed brazing material in the surfaces, applying the brazing material to the surfaces, and heating the brazing material to form a brazement between the components.

  10. Diffusion Brazing of Ti-6Al-4V and Stainless Steel 316L Using AgCuZn Filler Metal

    Directory of Open Access Journals (Sweden)

    R. Soltani Tashi

    2013-09-01

    Full Text Available In the present study, vacuum brazing was applied to join Ti-6Al-4V and stainless steel using AgCuZn filler metal. The bonds were characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction analysis. Mechanical strengths of the joints were evaluated by the shear test and microhardness. It has been shown that shear strength decreased with increasing the brazing temperature and time. The wettability of the filler alloy was increased by enhancing the wetting test temperature. By increasing the brazing temperature various intermetallic compounds were formed in the bond area. These intermetallic compounds were mainly a combination of CuTi and Fe-Cu-Ti. The shear test results verified the influence of the bonding temperature on the strength of the joints based on the formation of different intermetallics in the bond zone. The fracture analysis also revealed different fracture footpath and morphology for different brazing temperatures.

  11. Advances in brazing science, technology and applications

    CERN Document Server

    2013-01-01

    Brazing processes offer enhanced control, adaptability and cost-efficiency in the joining of materials. Unsurprisingly, this has lead to great interest and investment in the area. Drawing on important research in the field, Advances in brazing provides a clear guide to the principles, materials, methods and key applications of brazing. Part one introduces the fundamentals of brazing, including molten metal wetting processes, strength and margins of safety of brazed joints, and modeling of associated physical phenomena. Part two goes on to consider specific materials, such as super alloys, filler metals for high temperature brazing, diamonds and cubic boron nitride, and varied ceramics and intermetallics. The brazing of carbon-carbon (C/C) composites to metals is also explored before applications of brazing and brazed materials are discussed in part three. Brazing of cutting materials, use of coating techniques, and metal-nonmetal brazing for electrical, packaging and structural applications are reviewed, alon...

  12. Evaluation of Corrosion Performance of Titanium/Steel Joint Brazed by Cu-Based Filler Metal

    Science.gov (United States)

    Elrefaey, A.; Wojarski, L.; Tillmann, W.

    2012-05-01

    Furnace vacuum brazing has been employed to join commercially pure titanium and low carbon steel using copper-based filler metal with the composition of Cu-10.6Mn-1.9Ni, at.%. Three different brazing temperatures 930, 970, and 1000 °C and a holding time of 15 min were studied and evaluated. The corrosion behavior of the joint in 0.1 M sulfuric acid was investigated using immersion and electrochemical tests. Measurements of corrosion potential, corrosion current density, corrosion rate, polarization resistance, weight loss, and morphology of corrosion attack were used in this study. Experimental results showed that severe corrosion attack of the steel side at the interfacial area is clearly observed. Despite the difference in corrosion rate values obtained by electrochemical and weight loss measurements, the trend of results was identical to a large extent. Corrosion resistance of the joint showed a general tendency to increase with rising brazing temperature. The lowest corrosion rate was obtained for the couple bonded at 1000 °C. Meanwhile, at the lowest joining temperature of 930 °C, corrosion rate showed a higher value. The results of joints corrosion resistance were attributed to the difference in microstructure features and chemical analysis.

  13. Research on Microstructure and Mechanical Properties of Wide-gap Brazed Joints of K465 Superalloy Using Nickel-base Brazing Filler Metal

    Directory of Open Access Journals (Sweden)

    PAN Hui

    2017-05-01

    Full Text Available The joint clearance with 0.5mm was brazed with pre-filled high-melting powder method, by using K465 nickel-base superalloy as base metal, FGH95 nickel-base superalloy powder as pre-filled powder. The effects of different holding time on microstructure and mechanical properties were investigated. The results show that the brazing seam microstructure of the joints brazed at 1220℃ for 0.5h composes of alloy powder particles and phases among the particles. The microstructure is a two-phase structure of γ and γ' inside the powder particles, and among the particles are γ and γ' two-phase based borides, silicides and γ+γ' eutectics. With the increase of holding time, the powder particles grow bigger, the compounds and γ+γ' eutectics merge together, leads to the decrease of the amount of compounds and γ+γ'eutectics. The holding time is prolonged from 0.5h to 16h, the average rupture life increases from 31.59h to 54.58h, but it is not easy to achieve the isothermally solidified joints with good mechanical properties.

  14. Active Metal Brazing and Adhesive Bonding of Titanium to C/C Composites for Heat Rejection System

    Science.gov (United States)

    Singh, M.; Shpargel, Tarah; Cerny, Jennifer

    2006-01-01

    Robust assembly and integration technologies are critically needed for the manufacturing of heat rejection system (HRS) components for current and future space exploration missions. Active metal brazing and adhesive bonding technologies are being assessed for the bonding of titanium to high conductivity Carbon-Carbon composite sub components in various shapes and sizes. Currently a number of different silver and copper based active metal brazes and adhesive compositions are being evaluated. The joint microstructures were examined using optical microscopy, and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). Several mechanical tests have been employed to ascertain the effectiveness of different brazing and adhesive approaches in tension and in shear that are both simple and representative of the actual system and relatively straightforward in analysis. The results of these mechanical tests along with the fractographic analysis will be discussed. In addition, advantages, technical issues and concerns in using different bonding approaches will also be presented.

  15. Development of rapidly quenched nickel-based non-boron filler metals for brazing corrosion resistant steels

    Science.gov (United States)

    Ivannikov, A.; Kalin, B.; Suchkov, A.; Penyaz, M.; Yurlova, M.

    2016-04-01

    Corrosion-resistant steels are stably applied in modern rocket and nuclear technology. Creating of permanent joints of these steels is a difficult task that can be solved by means of welding or brazing. Recently, the use rapidly quenched boron-containing filler metals is perspective. However, the use of such alloys leads to the formation of brittle borides in brazing zone, which degrades the corrosion resistance and mechanical properties of the compounds. Therefore, the development of non-boron alloys for brazing stainless steels is important task. The study of binary systems Ni-Be and Ni-Si revealed the perspective of replacing boron in Ni-based filler metals by beryllium, so there was the objective of studying of phase equilibrium in the system Ni-Be-Si. The alloys of the Ni-Si-Be with different contents of Si and Be are considered in this paper. The presence of two low-melting components is revealed during of their studying by methods of metallography analysis and DTA. Microhardness is measured and X-ray diffraction analysis is conducted for a number of alloys of Ni-Si-Be. The compositions are developed on the basis of these data. Rapidly quenched brazing alloys can be prepared from these compositions, and they are suitable for high temperature brazing of steels.

  16. SCIP - Self-Cleaning Inert-Gas Brazing - a new process for brazing corrosion-resistant metals; SCIB - Self-Cleaning Inert-Gas Brazing - Ein neues Verfahren zum flussmittelfreien Hartloeten korrosionsbestaendiger Konstruktionswerkstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Bach, F.W.; Moehwald, K. [Hannover Univ. (Germany). Inst. fuer Werkstoffkunde; Hollaender, U.; Roxlau, C. [Leipzig Univ. Hannover, Garbsen (Germany)

    2007-07-01

    In flux-free inert gas furnace welding of corrosion-resistant metals, even very small water or oxygen impurities will dramatically reduce the quality of the brazed joint. A high-quality process atmosphere is ensured on the one hand by intelligent furnace design and on the other hand by the use of high-purity inert or reducing gases. The high quality demands on the process gases are an important cost factor especially in once-through furnaces. Further, gas purity with less than 1 ppm residual oxygen or water cannot be ensured so that inert gas welding of extremely oxidation-sensitive materials is not possible in principle. The contribution presents the new process of self-cleaning inert gas brazing (SCIB), in which conventional inert gases are doped with gaseous hydrides which cause direct and quantitative removal of all oxidizing impurities in the process gas already at room temperature. The concentration of residual oxygen and water in the inert gas is thus reduced to below the theoretical detection limit. The contribution describes the physical and chemical effective mechanism of the non-corrosive additives and presents experimental results with SCIB in flux-free brazing of sensitive construction materials in a conventional once-through inert gas furnace. (orig.)

  17. Metallurgical reactions in the coalescence zone between a reinforcement and a base metal in reinforced brazed joints

    Directory of Open Access Journals (Sweden)

    Zorc, B.

    2004-12-01

    Full Text Available A reinforcement wire added to a brazed joint strongly improves the properties of the joint, i.e., its strength, toughness and resistance to crack initiation and propagation. This effect, however, can be achieved only if the reinforcement wire is of a suitable shape, from an appropriate material as regards the base metal and the brazing alloy and it coalesces strongly and toughly with the base metal. The properties of such a joint depend on the reinforcement wire and not on the brazing alloy. The most favourable reinforcement shape was determined. Metallurgical reactions among the base metal, the brazing alloy, and the reinforcement were studied.

    La armadura, añadida a las uniones fuertemente soldadas, mejora considerablemente las características de la unión, es decir, su dureza, tenacidad y resistencia frente a la formación y propagación de la grieta separada. Se puede alcanzar dicho resultado solamente si el alambre de la armadura tiene la forma apropiada, está formado con el material adecuado (acorde al material de base y la unión y se funde de manera fuerte y tenaz con el material de base. Las propiedades de la unión mencionada, dependen del alambre de la armadura y no de la soldadura. Se determina la forma más ventajosa de la armadura y se investigan las reacciones metalúrgicas entre el material de base, la soldadura y la armadura.

  18. Development of metal-ceramic brazed joints for high temperature applications: example of SiC-Inconel joints

    Energy Technology Data Exchange (ETDEWEB)

    Baffie, T. [CEA/LITEN-DTH, Lab. of Hydrogen Technologies, Grenoble (France); Ziombra, A. [RWTH Aachen (Germany); Schicktanz, R. [BURGMANN Industries, Wolfratshausen (Germany)

    2007-07-01

    For many applications, sintered silicon carbide SiC, used in high temperature and corrosive environments, has to be brazed to a metal. Nowadays, there is still no tight solution for SiC/metal joints working higher than 400 C; this is mainly explained by chemical (high reactivity) and thermomechanical (high thermal expansion mismatch) incompatibilities between ceramics and metals. These two key points were addressed through the use of a low-active filler metal and interlayer materials. Numerical simulation was employed to optimise the design of the joints and the shape of the parts and thus, reduce stresses on SiC. SiC/metal brazed prototypes of industrial parts were fabricated and tested up to 400 C and failure. (orig.)

  19. Atom Probe Tomography and Its Application to Refractory Metal Nuggets

    Science.gov (United States)

    Daly, L.; Bland, P. A.; Forman, L. V.; Reddy, S. M.; Rickard, W. D. A.; Saxey, D. W.; La Fontaine, A.; Yang, L.; Trimby, P. W.; Cairney, J.; Ringer, S.; Schaefer, B. F.

    2016-08-01

    Atom probe tomography is capable of achieving atomic resolution. This allows us to accurately measure the chemistry of refractory metal nuggets in situ, revealing nanometre scale variations in their chemistry and the presence of sulphur in the alloy.

  20. Finite element modelling for thermal analysis of stud-to-plate laser brazing for a dissimilar metal joint

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jun Soo; Kim, Jong Min [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-06-01

    A finite element model was developed for the thermal analysis of a stud-to-plate laser brazing joint, and the transient temperature fields were analysed by using a three-dimensional model. The finite element program ABAQUS, together with a few user subroutines, was employed to perform the numerical approximation. Temperature-dependent thermal properties, effect of latent heat, and the convection and radiative heat losses were considered. The brazing parts used were AISI 304 stainless steel stud and aluminium A1 5052 plate, and the brazing alloy 88 A1-12 Si was used as filler metal. A pseudo-TM{sub 01} mode of the cw CO{sub 2} laser beam was used as heat source, for which TM{sub 00} mode generated by beam oscillator was optically modulated using axicon lens. Re-location of the filler metal during the brazing process including its wetting and spreading was examined by using a high speed motion analyser, and the results were incorporated inn the FEM modelling for defining the solution domain and boundary conditions. The numerical results were obtained for typical process parameters, and were compared with experimental ones determined by using the infrared and thermocouple measurements. 11 figs., 30 refs. (Author).

  1. The dissimilar brazing of Kovar alloy to SiCp/Al composites using silver-based filler metal foil

    Science.gov (United States)

    Wang, Peng; Xu, Dongxia; Zhai, Yahong; Niu, Jitai

    2017-09-01

    Aluminum metal matrix composites with high SiC content (60 vol.% SiCp/Al MMCs) were surface metallized with a Ni-P alloy coating, and vacuum brazing between the composites and Kovar alloy were performed using rapidly cooled Ag-22.0Cu-15.9In-10.86Sn-1.84Ti (wt%) foil. The effects of Ni-P alloy coating and brazing parameters on the joint microstructures and properties were researched by SEM, EDS, and single lap shear test, respectively. Results show that Ag-Al intermetallic strips were formed in the 6063Al matrix and filler metal layer because of diffusion, and they were arranged regularly and accumulated gradually as the brazing temperature was increased ( T/°C = 550-600) or the soaking time was prolonged ( t/min = 10-50). However, excessive strips would destroy the uniformity of seams and lead to a reduced bonding strength (at most 70 MPa). Using a Ni-P alloy coating, void free joints without those strips were obtained at 560 °C after 20 min soaking time, and a higher shear strength of 90 MPa was achieved. The appropriate interface reaction ( 2 μm transition layer) that occurred along the Ni-P alloy coating/filler metal/Kovar alloy interfaces resulted in better metallurgical bonding. In this research, the developed Ag-based filler metal was suitable for brazing the dissimilar materials of Ni-P alloy-coated SiCp/Al MMCs and Kovar alloy, and capable welding parameters were also broadened.

  2. THE DISTRIBUTION OF FILLER MATERIAL ON BASE METALS DURING BRAZING OF ALUMINUM ALLOYS

    Directory of Open Access Journals (Sweden)

    Andrei DIMITRESCU

    2013-05-01

    Full Text Available Since aluminum brazing technology is relatively new compared to other permanent joiningtechnologies, this technological process needs a scientific approach.One of the specific parameters of this type of technological processes is the distribution of fillermaterial on base material. This parameter affects directly the quality of the brazed assembly

  3. Directed light fabrication of refractory metals and alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, J.C.; Lewis, G.K.; Dickerson, P.G.; Nemec, R.B.

    1999-05-30

    This report covers deposition of refractory pure metals and alloys using the Directed Light Fabrication (DLF) process and represents progress in depositing these materials through September 1998. In extending the DLF process technology to refractory metals for producing fully dense, structurally sound deposits, several problems have become evident. (1) Control of porosity in DLF-deposited refractory metal is difficult because of gases, apparently present in commercially purchased refractory metal powder starting materials. (2) The radiant heat from the molten pool during deposition melts the DLF powder feed nozzle. (3) The high reflectivity of molten refractory metals, at the Nd-YAG laser wavelength (1.06{micro}m), produces damaging back reflections to the optical train and fiber optic delivery system that can terminate DLF processing. (4) The current limits on the maximum available laser power to prevent back reflection damage limit the parameter range available for densification of refractory metals. The work to date concentrated on niobium, W-25Re, and spherodized tungsten. Niobium samples, made from hydride-dehydride powder, had minimal gas porosity and the deposition parameters were optimized; however, test plates were not made at this time. W-25Re samples, containing sodium and potassium from a precipitation process, were made and porosity was a problem for all samples although minimized with some process parameters. Deposits made from potassium reduced tungsten that was plasma spherodized were made with minimized porosity. Results of this work indicate that further gas analysis of starting powders and de-gassing of starting powders and/or gas removal during deposition of refractory metals is required.

  4. Directed Light Fabrication of Refractory Metals and Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, J.C.; Lewis, G.K.; Dickerson, P.G.; Nemec, R.B.

    1999-05-14

    This report covers work performed under Order No. FA0000020 AN Contract DE-AC12-76SN00052 for deposition of refractory pure metals and alloys using the Directed Light Fabrication (DLF) process and represents the progress in depositing these materials through September 1998. In extending the DLF process technology to refractory metals for producing fully dense, structurally sound deposits, several problems have become evident. 1. Control of porosity in DLF-deposited refractory metal is difficult because of gases, apparently present in commercially purchased refractory metal powder starting materials. 2. The radiant heat from the molten pool during deposition melts the DLF powder feed nozzle. 3. The high reflectivity of molten refractory metals, at the Nd-YAG laser wavelength (1.06{micro}m), produces damaging back reflections to the optical train and fiber optic delivery system that can terminate DLF processing. 4. The current limits on the maximum available laser power to prevent back reflection damage limit the parameter range available for densification of refractory metals. The work to date concentrated on niobium, W-25Re, and spherodized tungsten. Niobium samples, made from hydride-dehydride powder, had minimal gas porosity and the deposition parameters were optimized; however, test plates were not made at this time. W-25Re samples, containing sodium and potassium from a precipitation process, were made and porosity was a problem for all samples although minimized with some process parameters. Deposits made from potassium reduced tungsten that was plasma spherodized were made with minimized porosity. Results of this work indicate that further gas analysis of starting powders and de-gassing of starting powders and/or gas removal during deposition of refractory metals is required.

  5. Effect of filler metal composition on the strength of yttria stabilized zirconia joints brazed with Pd-Ag-CuOx

    Energy Technology Data Exchange (ETDEWEB)

    Darsell, Jens T.; Weil, K. Scott

    2008-09-08

    The Ag-CuOx system is of interest to be used to be used as an air braze filler metal for joining high temperature electrochemical devices. Previous work has shown that the melting temperatures can be increased by adding palladium to Ag-CuOx and it is expected that this may aid high temperature stability. This work compares the room temperature bend strength of joints made between yttria-stabilized zirconia (YSZ) air brazed using Ag-CuOx without palladium and with 5 and 15mol% palladium additions. It has been found that in general palladium decreases joint strength, especially in low copper oxide compositions filler metals. At high copper oxide contents, brittle fracture through both copper oxide rich phases and the YSZ limits joint strength.

  6. Grey–Taguchi method to optimize the percent zinc coating balances edge joints for galvanized steel sheets using metal inert gas pulse brazing process

    Directory of Open Access Journals (Sweden)

    Khasempong Songsorn

    2016-06-01

    Full Text Available The objective of this work was to optimize the percent zinc coating balances edge joints of galvanized steel sheets using the metal inert gas pulse brazing process. The Taguchi method and grey relational analysis were used to determine the relationship between the metal inert gas pulse brazing process parameters and percent zinc coating balances edge joints. The metal inert gas pulse brazing process parameters used in this study included wire feed speeds, arc voltages, travel speed, peak currents, and pulse frequency. The characteristics of metal inert gas pulse brazing process that were considered to find response were percent zinc coating balances edge joints on the upper edge joint (PZBEJ1, the lower edge joint (PZBEJ2, and the back sides of the edge joint (PZBEJ3. Analysis of variance was performed to determine the impact of an individual process parameter on the quality parameters. The results showed that the optimal parameters in which grey relational grade increases at the highest level were wire feed speeds at 3.25 m/min, arc voltages at 16 V, travel speeds at 0.9 m/min, peak currents at 425 A, and pulse frequency at 35 Hz. These parameters gave a 74.90% higher response value than those of the initial parameters of metal inert gas pulse brazing process.

  7. Reactions Between MgO-C Refractory, Molten Slag and Metal

    National Research Council Canada - National Science Library

    Li, Zushu; Mukai, Kusuhiro; Tao, Zainan

    2000-01-01

    The behavior of MgO-C refractory-slag-metal system, which is caused by the reactions such as the dissolution of MgO and graphite in the refractory into slag and metal respectively and the generation...

  8. Induction brazing at the Kennedy Space Center

    Science.gov (United States)

    Clautice, W. E.

    1974-01-01

    A description of the joint design, materials, equipment, qualification testing, inspection methods, and applications involved in performing induction brazing on hyperbolic propellants tubing at Kennedy Space Center. Induction brazing is a form of brazing in which the energy is transmitted to the workpiece by electrical induction; the eddy currents generated in the metal produce heat by resistance losses. Since induction heating is fast and highly localized, undesirable heat effects are minimized and the resulting braze is of high quality.

  9. Refractory metal nuggets in different types of cosmic spherules.

    Digital Repository Service at National Institute of Oceanography (India)

    Rudraswami, N.G.; ShyamPrasad, M.; Plane, J.M.C.; Berg, T.; Feng, W.; Balgar, S.

    Out of the three basic cosmic spherule types collected from the seafloor, RMNs (refractory metal nuggets) have been reported from I-type spherules commonly, rarely from S-type spherules and never from the G-type spherules. Nuggets in the I-type...

  10. Process for forming unusually strong joints between metals and ceramics by brazing at temperatures that do not exceed 750/sup 0/C

    Science.gov (United States)

    Hammond, J.P.; David, S.A.; Woodhouse, J.J.

    1984-12-04

    This invention is a process for joining metals to ceramics to form very strong bonds using low brazing temperature, i.e., less than 750/sup 0/C, and particularly for joining nodular cast iron to partially stabilized zirconia. The process provides that the ceramic be coated with an active metal, such as titanium, that can form an intermetallic with a low melting point brazing alloy such as 60Ag-30Cu-10Sn. The nodular cast iron is coated with a noncarbon containing metal, such as copper, to prevent carbon in the nodular cast iron from dissolving in the brazing alloy. These coated surfaces can be brazed together with the brazing alloy between at less than 750/sup 0/C to form a very strong joint. An even stronger bond can be formed if a transition piece is used between the metal and ceramic. It is preferred for the transition piece to have a coefficient of thermal expansion compatible with the coefficient of thermal expansion of the ceramic, such as titanium.

  11. Simulation of Zr content in TiZrCuNi brazing filler metal for Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Xishan [Northwestern Polytechnical University, School of Astronautics, Xi' an (China); AVIC Beijing Aeronautical Manufacturing Technology Research Institute, Aeronautical Key Laboratory for Welding and Joining Technology, Beijing (China); Xie, Zonghong [Northwestern Polytechnical University, School of Astronautics, Xi' an (China); Jing, Yongjuan [AVIC Beijing Aeronautical Manufacturing Technology Research Institute, Aeronautical Key Laboratory for Welding and Joining Technology, Beijing (China)

    2017-07-15

    To optimize the Zr content in Ti-based filler metal, the covalent electron on the nearest atoms bond in unit cell (n{sub A}{sup u-v}) with Ti-based BCC structure was calculated, in which the brazing temperature was considered due to its influence on the lattice parameter. Based on EET theory (The Empirical Electron Theory for solid and molecules), n{sub A}{sup u-v} represents the strength of the unit cell with defined element composition and structure, which reflects the effect from solid solution strengthening on the strength of the unit cell. For Ti-Zr-15Cu-10Ni wt% filler metal, it kept constant as 0.3476 with Zr as 37.5 ∝ 45 wt% and decreased to 0.333 with Zr decreasing from 37.5 to 25 wt%. Finally, it increased up to 0.3406 with Zr as 2 ∝ 10 wt%. Thus, Ti-based filler metal with Zr content being 2 ∝ 10 wt% is suggested based on the simulation results. Moreover, the calculated covalent electron of n{sub A}{sup u-v} showed good agreement with the hardness of the joint by filler 37.5Zr and 10Zr. The composition of Ti-10Zr-15Cu-10Ni wt% was verified in this study with higher tensile strength of the brazing joint and uniform microstructure of the interface. (orig.)

  12. Compatibility between Co-Metallized PbTe Thermoelectric Legs and an Ag-Cu-In Brazing Alloy.

    Science.gov (United States)

    Ben-Ayoun, Dana; Sadia, Yatir; Gelbstein, Yaniv

    2018-01-10

    In thermoelectric (TE) generators, maximizing the efficiency of conversion of direct heat to electricity requires the reduction of any thermal and electrical contact resistances between the TE legs and the metallic contacts. This requirement is especially challenging in the development of intermediate to high-temperature TE generators. PbTe-based TE materials are known to be highly efficient up to temperatures of around 500 °C; however, only a few practical TE generators based on these materials are currently commercially available. One reason for that is the insufficient bonding techniques between the TE legs and the hot-side metallic contacts. The current research is focused on the interaction between cobalt-metallized n-type 9.104 × 10-3 mol % PbI₂-doped PbTe TE legs and the Ag0.32Cu0.43In0.25 brazing alloy, which is free of volatile species. Clear and fine interfaces without any noticeable formation of adverse brittle intermetallic compounds were observed following prolonged thermal treatment testing. Moreover, a reasonable electrical contact resistance of ~2.25 mΩmm² was observed upon brazing at 600 °C, highlighting the potential of such contacts while developing practical PbTe-based TE generators.

  13. Simulation of Zr content in TiZrCuNi brazing filler metal for Ti6Al4V alloy

    Science.gov (United States)

    Yue, Xishan; Xie, Zonghong; Jing, Yongjuan

    2017-07-01

    To optimize the Zr content in Ti-based filler metal, the covalent electron on the nearest atoms bond in unit cell ( n A u-v ) with Ti-based BCC structure was calculated, in which the brazing temperature was considered due to its influence on the lattice parameter. Based on EET theory (The Empirical Electron Theory for solid and molecules), n_{{A}}^{{u - v}} represents the strength of the unit cell with defined element composition and structure, which reflects the effect from solid solution strengthening on the strength of the unit cell. For Ti-Zr-15Cu-10Ni wt% filler metal, it kept constant as 0.3476 with Zr as 37.5˜45 wt% and decreased to 0.333 with Zr decreasing from 37.5 to 25 wt%. Finally, it increased up to 0.3406 with Zr as 2˜10 wt%. Thus, Ti-based filler metal with Zr content being 2˜10 wt% is suggested based on the simulation results. Moreover, the calculated covalent electron of n A u-v showed good agreement with the hardness of the joint by filler 37.5Zr and 10Zr. The composition of Ti-10Zr-15Cu-10Ni wt% was verified in this study with higher tensile strength of the brazing joint and uniform microstructure of the interface.

  14. Brazing method

    Science.gov (United States)

    McCormick, James T.; Ferry, Paul B.; Hall, John C.

    1981-10-06

    There is disclosed a positive cathode electrode structure formed by brazing a thin porous membrane to a backing material by preselecting a predetermined area of the thin porous membrane and thereafter providing a braze flow barrier throughout the remainder of the membrane and electrolessly plating a nickel-phosphide alloy on the backing material, or in this case the honeycomb structure. The preselected area of the thin porous membrane is placed in intimate contact with the electrolessly plated portion of the backing material and heated to elevated temperatures in the absence of oxygen to form a brazed joint limited to a preselected area. If the braze flow barrier is provided by application of a liquid organic solvent, then the organic solvent is driven off by maintaining the thin porous membrane at elevated temperatures for an extended period of time prior to the brazing operation.

  15. Titanium brazing with mechanically alloyed Ti-Zr-Cu-Ni braze powders

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.W. [Materials Resources International, Landsdale (United States); Shapiro, A. [Titanium Brazing, Inc., Upper Arlington (United States); Ivanov, E. [Tosoh, SMD, Inc., Columbus, OH (United States)

    2004-07-01

    The paper reviews the results of braze trials with Ti-Zr-Cu-Ni braze alloy powders. The work presented is based on the braze assembly of titanium alloys being considered for lightweight heat exchangers for aircraft applications. The report reviews the braze coupon tests, showing joint structures, braze filler metal structures as well as reports on local and overall composition of the braze powders and the joints. Various braze cycles are evaluated and selected comparisons are made between mechanically alloyed powders and prealloyed (gas atomized) braze filler metals. SEM, EDAX, and microprobe are reported for joints made from C.P. titanium (ASTM Grade 1 and Ti-6Al-4V) and Timet {sup registered} Alloy 21S. (orig.)

  16. Refractory metal alloys and composites for space nuclear power systems

    Science.gov (United States)

    Titran, Robert H.; Stephens, Joseph R.; Petrasek, Donald W.

    1988-01-01

    Space power requirements for future NASA and other U.S. missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the Space Shuttle may be used a minimum number of times to put the power supply into orbit. Nuclear power has been identified as the primary power source to meet these high levels of electrical demand. One method to achieve maximum efficiency is to operate the power supply, energy conservation system, and related components at relatively high temperatures. For systems now in the planning stages, design temperatures range from 1300 K for the immediate future to as high as 1700 K for the advanced systems. NASA Lewis Research Center has undertaken a research program on advanced technology of refractory metal alloys and composites that will provide baseline information for space power systems in the 1900's and the 21st century. Special emphasis is focused on the refractory metal alloys of niobium and on the refractory metal composites which utilize tungsten alloy wires for reinforcement. Basic research on the creep and creep-rupture properties of wires, matrices, and composites are discussed.

  17. Laser Brazing of High Temperature Braze Alloy

    Science.gov (United States)

    Gao, Y. P.; Seaman, R. F.; McQuillan, T. J.; Martiens, R. F.

    2000-01-01

    The Space Shuttle Main Engine (SSME) consists of 1080 conical tubes, which are furnace brazed themselves, manifolds, and surrounding structural jacket making almost four miles of braze joints. Subsequent furnace braze cycles are performed due to localized braze voids between the coolant tubes. SSME nozzle experiences extremely high heat flux (180 mW/sq m) during hot fire. Braze voids between coolant tubes may result in hot combustion gas escape causing jacket bulges. The nozzle can be disqualified for flight or result in mission failure if the braze voids exceed the limits. Localized braze processes were considered to eliminate braze voids, however, damage to the parent materials often prohibited use of such process. Being the only manned flight reusable rocket engine, it has stringent requirement on the braze process. Poor braze quality or damage to the parent materials limits the nozzle service life. The objective of this study was to develop a laser brazing process to provide quality, localized braze joints without adverse affect on the parent materials. Gold (Au-Cu-Ni-Pd-Mn) based high temperature braze alloys were used in both powder and wire form. Thin section iron base superalloy A286 tube was used as substrate materials. Different Laser Systems including CO2 (10.6 micrometers, 1kW), ND:YAG (1.06 micrometers, 4kW). and direct diode laser (808nm. 150W) were investigated for brazing process. The laser process variables including wavelength. laser power, travel speed and angle of inclination were optimized according to bead geometry and braze alloy wetting at minimum heat input level, The properties of laser brazing were compared to that of furnace brazing. Microhardness profiles were used for braze joint property comparison between laser and furnace brazing. The cooling rate of laser brazing was compared to furnace brazing based on secondary dendritic arm spacing, Both optical and Scanning Electron Microscope (SEM) were used to evaluate the microstructures of

  18. METHOD OF BRAZING BERYLLIUM

    Science.gov (United States)

    Hanks, G.S.; Keil, R.W.

    1963-05-21

    A process is described for brazing beryllium metal parts by coating the beryllium with silver (65- 75 wt%)-aluminum alloy using a lithium fluoride (50 wt%)-lithium chloride flux, and heating the coated joint to a temperature of about 700 un. Concent 85% C for about 10 minutes. (AEC)

  19. 40 CFR 471.50 - Applicability; description of the refractory metals forming subcategory.

    Science.gov (United States)

    2010-07-01

    ... refractory metals forming subcategory. 471.50 Section 471.50 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS NONFERROUS METALS FORMING AND METAL POWDERS POINT SOURCE CATEGORY Refractory Metals Forming Subcategory § 471.50 Applicability; description of the...

  20. Silver-hafnium braze alloy

    Science.gov (United States)

    Stephens, Jr., John J.; Hosking, F. Michael; Yost, Frederick G.

    2003-12-16

    A binary allow braze composition has been prepared and used in a bonded article of ceramic-ceramic and ceramic-metal materials. The braze composition comprises greater than approximately 95 wt % silver, greater than approximately 2 wt % hafnium and less than approximately 4.1 wt % hafnium, and less than approximately 0.2 wt % trace elements. The binary braze alloy is used to join a ceramic material to another ceramic material or a ceramic material, such as alumina, quartz, aluminum nitride, silicon nitride, silicon carbide, and mullite, to a metal material, such as iron-based metals, cobalt-based metals, nickel-based metals, molybdenum-based metals, tungsten-based metals, niobium-based metals, and tantalum-based metals. A hermetic bonded article is obtained with a strength greater than 10,000 psi.

  1. Method for controlling brazing

    Science.gov (United States)

    Hosking, F Michael [Albuquerque, NM; Hall, Aaron C [Albuquerque, NM; Givler, Richard C [Albuquerque, NM; Walker, Charles A [Albuquerque, NM

    2006-08-01

    A method for making a braze joint across a discontinuity in a work piece using alternating current. A filler metal is pre-placed at a location sufficiently close to the discontinuity such that, when an alternating current is applied across a work piece to heat the work piece and melt the filler metal, the filler metal is drawn into the discontinuity. The alternating current is maintained for a set residence time, generally less than 10 seconds and more particularly less than 3 seconds. The alternating current is then altered, generally by reducing the current and/or voltage such that the filler metal can solidify to form a braze joint of desired quality and thickness.

  2. Susceptor heating device for electron beam brazing

    Science.gov (United States)

    Antieau, Susan M.; Johnson, Robert G. R.

    1999-01-01

    A brazing device and method are provided which locally apply a controlled amount of heat to a selected area, within a vacuum. The device brazes two components together with a brazing metal. A susceptor plate is placed in thermal contact with one of the components. A serrated pedestal supports the susceptor plate. When the pedestal and susceptor plate are in place, an electron gun irradiates an electron beam at the susceptor plate such that the susceptor plate is sufficiently heated to transfer heat through the one component and melt the brazing metal.

  3. Processing of Refractory Metal Alloys for JOYO Irradiations

    Energy Technology Data Exchange (ETDEWEB)

    RF Luther; ME Petrichek

    2006-02-21

    This is a summary of the refractory metal processing experienced by candidate Prometheus materiats as they were fabricated into specimens destined for testing within the JOYO test reactor, ex-reactor testing at Oak Ridge National Laboratory (ORNL), or testing within the NRPCT. The processing is described for each alloy from the point of inception to the point where processing was terminated due to the cancellation of Naval Reactor's involvement in the Prometheus Project. The alloys included three tantalum-base alloys (T-111, Ta-10W, and ASTAR-811C), a niobium-base alloy, (FS-85), and two molybdenum-rhenium alloys, one containing 44.5 w/o rhenium, and the other 47.5 w/o rhenium. Each of these alloys was either a primary candidate or back-up candidate for cladding and structural applications within the space reactor. Their production was intended to serve as a forerunner for large scale production ingots that were to be procured from commercial refractory metal vendors such as Wah Chang.

  4. Brazing, high temperature brazing and diffusion welding. Lectures and posters; Hart- und Hochtemperaturloeten und Diffusionsschweissen. Vortraege und Posterbeitraege

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    This paper contains lectures and poster with the following main topics: Fundamentals and industrial application of brazing; Joining of cemented carbides, hard metals, cermets; Diffusion bonding, micro- and nanotechnologies, corrosion and corrosion protection, integration of brazing into the production process; Joining of glass, ceramics, metals; Joining techniques in fuel cells; Joining with Fe-based filler metals; Joining of high performance materials; Arc brazing and beam brazing; Designing suitable for brazing / Corrosion and corrosion protection / Inspection; Joining of light weight metals; Functional surfaces / Modeling an simulation.

  5. Synthesis, Structure, and Properties of Refractory Hard-Metal Borides

    Science.gov (United States)

    Lech, Andrew Thomas

    As the limits of what can be achieved with conventional hard compounds, such as tungsten carbide, are nearing reach, super-hard materials are an area of increasing industrial interest. The refractory hard metal borides, such as ReB2 and WB4, offer an increasingly attractive alternative to diamond and cubic boron nitride as a next-generation tool material. In this Thesis, a thorough discussion is made of the progress achieved by our laboratory towards understanding the synthesis, structure, and properties of these extremely hard compounds. Particular emphasis is placed on structural manipulation, solid solution formation, and the unique crystallographic manifestations of what might also be called "super-hard metals".

  6. A Ti–Zr–Cu–Ni–Co–Fe–Al–Sn amorphous filler metal for improving the strength of Ti–6Al–4V alloy brazing joint

    Directory of Open Access Journals (Sweden)

    Lulu Sun

    2017-12-01

    Full Text Available Ti50Zr27Cu8Ni4Co3Fe2Al3Sn3 (at% amorphous filler metal with low Cu and Ni contents in a melt-spun ribbon form was developed for improving mechanical properties of Ti–6Al–4V alloy brazing joint through decreasing brittle intermetallics in the braze zone. Investigation on the crystallization behavior of the multicomponent Ti–Zr–Cu–Ni–Co–Fe–Al–Sn amorphous alloy indicates the high stability of the supercooled liquid against crystallization that favors the formation of amorphous structure. The Ti–6Al–4V joint brazed with this Ti-based amorphous filler metal with low total content of Cu and Ni at 1203 K for 900 s mainly consists of α-Ti, β-Ti, minor Ti–Zr-rich phase and only a small amount of Ti3Cu intermetallics, leading to the high shear strength of the joint of about 460 MPa. Multicomponent composition design of amorphous alloys is an effective way of tailoring filler metals for improving the joint strength.

  7. Phase Evolution in the Pd-Ag-CuO Air Braze Filler Metal Alloy System

    Energy Technology Data Exchange (ETDEWEB)

    Darsell, Jens T.; Weil, K. Scott

    2006-08-01

    Palladium was added as a ternary component to a series of copper oxide-silver alloys in an effort to increase the use temperature of these materials for potential ceramic air brazing applications. Phase equilibria in the ternary Pd-Ag-CuO system were investigated via differential scanning calorimetry (DSC) and a series of quenching experiments. Presented here are the latest findings on this system and a construction of the corresponding ternary phase diagram for low-to-moderate additions of palladium. The analysis included samples with higher palladium additions than were studied in the past, as well as an analysis of the composition-temperature trends in the Ag-CuO miscibility gap with palladium addition. It was found that the addition of palladium increases the solidus and liquidus and caused three phase zones to appear as expected by the phase rule. Furthermore, the palladium additions cause the miscibility gap boundary extending from the former binary eutectic to shift to lower silver-to-copper ratios.

  8. Thermally stable diamond brazing

    Science.gov (United States)

    Radtke, Robert P [Kingwood, TX

    2009-02-10

    A cutting element and a method for forming a cutting element is described and shown. The cutting element includes a substrate, a TSP diamond layer, a metal interlayer between the substrate and the diamond layer, and a braze joint securing the diamond layer to the substrate. The thickness of the metal interlayer is determined according to a formula. The formula takes into account the thickness and modulus of elasticity of the metal interlayer and the thickness of the TSP diamond. This prevents the use of a too thin or too thick metal interlayer. A metal interlayer that is too thin is not capable of absorbing enough energy to prevent the TSP diamond from fracturing. A metal interlayer that is too thick may allow the TSP diamond to fracture by reason of bending stress. A coating may be provided between the TSP diamond layer and the metal interlayer. This coating serves as a thermal barrier and to control residual thermal stress.

  9. Microstructures and Properties of FGH96/DD6 Joints Brazed at Vacuum Pressure State

    Directory of Open Access Journals (Sweden)

    ZOU Wenjiang

    2017-08-01

    Full Text Available Ni-Cr-B brazing filler was used to braze FGH96 and DD6 at 1120℃/10 min and 1120℃/10 min/2 MPa. The tensile strength of the joints was tested, the microstructures and fractures were observed by OM and SEM, and the reaction products were analyzed by EPMA. The results show that the joints brazed at vacuum pressure process offer the average tensile strength of 1187 MPa, outclass the joints brazed without pressure which has average tensile strength of 621 MPa. Compared with vacuum brazing, the grains of FGH96/DD6 joints brazed by vacuum pressure state penetrate the brazing seam without grain boundary and ductile fracture occurred in the parent metal surface. The Ni3B exists in the joints brazed by vacuum brazing, but it is (Ni, Cr solid solution in the joints brazed by vacuum pressure brazing instead of Ni3B.

  10. Relationship between welding fume concentration and systemic inflammation after controlled exposure of human subjects with welding fumes from metal inert gas brazing of zinc-coated materials.

    Science.gov (United States)

    Brand, Peter; Bauer, Marcus; Gube, Monika; Lenz, Klaus; Reisgen, Uwe; Spiegel-Ciobanu, Vilia Elena; Kraus, Thomas

    2014-01-01

    It has been shown that exposure of subjects to emissions from a metal inert gas (MIG) brazing process of zinc-coated material led to an increase of high-sensitivity C-reactive protein (hsCRP) in the blood. In this study, the no-observed-effect level (NOEL) for such emissions was assessed. Twelve healthy subjects were exposed for 6 hours to different concentrations of MIG brazing fumes under controlled conditions. High-sensitivity C-reactive protein was measured in the blood. For welding fumes containing 1.20 and 1.50 mg m zinc, high-sensitivity C-reactive protein was increased the day after exposure. For 0.90 mg m zinc, no increase was detected. These data indicate that the no-observed-effect level for emissions from a MIG brazing process of zinc-coated material in respect to systemic inflammation is found for welding fumes with zinc concentrations between 0.90 and 1.20 mg m.

  11. Breakdown resistance of refractory metals compared to copper

    CERN Document Server

    Taborelli, M; Kildemo, M

    2004-01-01

    The behaviour of Mo, W and Cu with respect to electrical breakdown in ultra high vacuum has been investigated by means of a capacitor discharge method. The maximum stable electric field without breakdown and the field enhancement factor, beta have been measured between electrodes of the same material in a sphere/plane geometry for anode and cathode, respectively. The maximum stable field increases as a function of the number of breakdown events for W and Mo. In contrast, no systematic increase is observed for Cu. The highest values obtained are typically 500 MV/m for W, 350 MV/m for Mo and only 180 MV/m for Cu. This conditioning, found for the refractory metals, corresponds to a simultaneous decrease of beta and is therefore related to the field emission properties of the surface and their modification upon sparking. Accordingly, high beta values and no applicable field increase occur for Cu even after repeated breakdown. The results are compared with RF breakdown experiments [1] performed on prototype 30 GHz...

  12. Automatic-Control System for Safer Brazing

    Science.gov (United States)

    Stein, J. A.; Vanasse, M. A.

    1986-01-01

    Automatic-control system for radio-frequency (RF) induction brazing of metal tubing reduces probability of operator errors, increases safety, and ensures high-quality brazed joints. Unit combines functions of gas control and electric-power control. Minimizes unnecessary flow of argon gas into work area and prevents electrical shocks from RF terminals. Controller will not allow power to flow from RF generator to brazing head unless work has been firmly attached to head and has actuated micro-switch. Potential shock hazard eliminated. Flow of argon for purging and cooling must be turned on and adjusted before brazing power applied. Provision ensures power not applied prematurely, causing damaged work or poor-quality joints. Controller automatically turns off argon flow at conclusion of brazing so potentially suffocating gas does not accumulate in confined areas.

  13. Brazing of Titanium with Aluminium Alloys

    Directory of Open Access Journals (Sweden)

    Winiowski A.

    2017-06-01

    Full Text Available This study presents results of vacuum diffusion brazing of Grade 2 titanium with 6082 (AlMg1Si0.6Cu0.3 aluminium alloy using B-Ag72Cu-780 (Ag72Cu28 grade silver brazing metal as an interlayer. Brazed joints underwent shear tests, light-microscopy-based metallographic examinations and structural examinations using scanning electron microscopy (SEM and X-ray energy dispersive spectrometry (EDS. The highest quality and shear strength of 20 MPa was characteristic of joints brazed at 530°C with a 30-minute hold. The structural examinations revealed that in diffusion zone near the boundary with titanium the braze contained solid solutions based on hard and brittle Ti-Al type intermetallic phases determining the strength of the joints.

  14. Induction brazing of complex joints

    DEFF Research Database (Denmark)

    Henningsen, Poul; Zhang, Wenqi; Bay, Niels

    2003-01-01

    Induction brazing is a fast and appropriate method for industrial joining of complex geometries and metal combinations. In all types of brazing processes it is important to heat the joint interface of the two materials to the same, high temperature. If one of the specimens is warmer than the other...... materials has large influence on the heating time and temperature distribution in induction heating. In order to ensure high and uniform temperature distribution near the interface of a joint between dissimilar materials the precise coil geometry and position is of great importance. The present paper...... presents a combined numerical and experimental method for fast determination of appropriate coil geometry and position in induction brazing tube-to-plate joints of different ratios between tube and plate thickness and different combinations of the materials stainless steel, brass and copper. The method has...

  15. Brazing graphite to graphite

    Science.gov (United States)

    Peterson, George R.

    1976-01-01

    Graphite is joined to graphite by employing both fine molybdenum powder as the brazing material and an annealing step that together produce a virtually metal-free joint exhibiting properties similar to those found in the parent graphite. Molybdenum powder is placed between the faying surfaces of two graphite parts and melted to form molybdenum carbide. The joint area is thereafter subjected to an annealing operation which diffuses the carbide away from the joint and into the graphite parts. Graphite dissolved by the dispersed molybdenum carbide precipitates into the joint area, replacing the molybdenum carbide to provide a joint of virtually graphite.

  16. Review Article: recent advances in metal-ceramic brazing Artigo Revisão: avanços recentes em brasagem metal-cerâmica

    Directory of Open Access Journals (Sweden)

    R. M. do Nascimento

    2003-12-01

    Full Text Available Metal-ceramic joining has slowly but steadily become an important manufacturing step. The evolution of joining processes has allowed ceramics to be used in combination with metals in a number of hybrid devices from traditional light bulbs and seals to improved cutting tools and modern monitoring and measuring electronic devices. New joining methods and newer approaches to conventional methods have been developed aiming at joints characterized by improved reliability, and interfaces capable of withstanding high-temperature resistance with minimum residual stresses. A summary of recent improvements on alternative approaches to ceramic-metal joining as well as new developments on brazing are presented herein. The present review also focuses on recent advances towards brazing metallized ceramics and the selection of filler alloys, since in a scenario that includes joining by laser and direct bonding with liquid transient phases, brazing continues to be by far the most widely used approach to joining as a result of its low-cost and possibility to join intricate geometries for large-scale production. Finally, methods to evaluate the mechanical strength and residual thermal stresses are presented in addition to alternative approaches to minimize residual stresses and, consequently, improve joint reliability.O interesse no estudo de métodos de junção-cerâmica para aplicações industriais tem crescido gradativamente ao longo dos anos. A evolução dos processos de união tem permitido a utilização de cerâmicas em conjunto com metais na fabricação de diversos componentes híbridos incluindo lâmpadas tradicionais, juntas para vácuo, ferramentas de corte de alto desempenho e modernos dispositivos eletrônicos de medição e monitoramento. Novos métodos de união e aprimoramentos de métodos convencionais têm sido estudados com o intuito de produzir-se juntas com alta confiabilidade e interfaces capazes de suportar altas temperaturas de

  17. Evaluation of Brazed Joints Using Failure Assessment Diagram

    Science.gov (United States)

    Flom, Yury

    2012-01-01

    Fitness-for service approach was used to perform structural analysis of the brazed joints consisting of several base metal / filler metal combinations. Failure Assessment Diagrams (FADs) based on tensile and shear stress ratios were constructed and experimentally validated. It was shown that such FADs can provide a conservative estimate of safe combinations of stresses in the brazed joints. Based on this approach, Margins of Safety (MS) of the brazed joints subjected to multi-axial loading conditions can be evaluated..

  18. Brazing of Stainless Steels to Yttria Stabilized Zirconia (YSZ) Using Silver -Base Brazes

    Science.gov (United States)

    Singh, Mrityunjay; Shpargel, Tarah P.; Asthana, Rajiv

    2005-01-01

    Three silver-base brazes containing either noble metal palladium (Palcusil-10 and Palcusil-15) or active metal titanium (Ticusil) were evaluated for high-temperature oxidation resistance, and their effectiveness in joining yttria stabilized zirconia (YSZ) to a corrosion-resistant ferritic stainless steel. Thermogravimetric analysis (TGA), and optical- and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) were used to evaluate the braze oxidation behavior and the structure and chemistry of the YSZ/braze/steel joints. The effect of the braze type and processing conditions on the interfacial microstructure and composition of the joint regions is discussed with reference to the chemical changes that occur at the interface. It was found that chemical interdiffusion of the constituents of YSZ, steel and the brazes led to compositional changes and/or interface reconstruction, and metallurgically sound joints.

  19. Failure Assessment Diagram for Titanium Brazed Joints

    Science.gov (United States)

    Flom, Yury; Jones, Justin S.; Powell, Mollie M.; Puckett, David F.

    2011-01-01

    The interaction equation was used to predict failure in Ti-4V-6Al joints brazed with Al 1100 filler metal. The joints used in this study were geometrically similar to the joints in the brazed beryllium metering structure considered for the ATLAS telescope. This study confirmed that the interaction equation R(sub sigma) + R(sub Tau) = 1, where R(sub sigma) and R(sub Tau)are normal and shear stress ratios, can be used as conservative lower bound estimate of the failure criterion in ATLAS brazed joints as well as for construction of the Failure Assessment Diagram (FAD).

  20. Brazing of Mo to a CuZr alloy for the production of bimetallic raw materials for the CLIC accelerating structures

    CERN Document Server

    Salvo, M; Heikkinen, Samuli; Salvo, Milena; Casalegno, Valentina; Sgobba, Stefano; Rizzo, Stefano; Izquierdo, Gonzalo Arnau; Taborelli, Mauro

    2010-01-01

    Future linear accelerators, as CLIC (Compact Linear Collider), are extremely demanding in terms of material properties. Traditionally accelerating structure is made of brazed OFE copper parts. For the high conducting regions submitted to mechanical fatigue, CuZr would represent an improved selection than pure copper while for regions where the highest electric field is applied a refractory metal, i.e. Mo, could result in a better performance. The feasibility of joining such materials, namely CuZr (UNS C15000) and pure Mo has been investigated. The joining method developed and investigated here consists in a vacuum brazing process exploiting a Cu-based brazing filler applied under appropriate vacuum conditions. Apparent shear strength (adapted from ASTM B898) on the joined samples was about 200 MPa. (C) 2010 Elsevier B.V. All rights reserved.

  1. Vacuum Brazing of WC-8Co Cemented Carbides to Carbon Steel Using Pure Cu and Ag-28Cu as Filler Metal

    Science.gov (United States)

    Zhang, X. Z.; Liu, G. W.; Tao, J. N.; Shao, H. C.; Fu, H.; Pan, T. Z.; Qiao, G. J.

    2017-02-01

    The wetting and spreading behavior of commercial pure Cu and Ag-28Cu alloy on WC-8Co cemented carbide were investigated by the sessile drop technique. The contact angle of both systems obviously decreases with moderately increasing the wetting temperature. Vacuum brazing of the WC-8Co cemented carbide to SAE1045 steel using the pure Cu or Ag-28Cu as filler metal was further carried out based on the wetting results. The interfacial interactions and joint mechanical behavior involving microhardness, shear strength and fracture were analyzed and discussed. An obvious Fe-Cu-Co transition layer is detected at the WC-8Co/Cu interface, while no obvious reaction layer is observed at the whole WC-8Co/Ag-28Cu/SAE1045 brazing seam. The microhardness values of the two interlayers and the steel substrate near the two interlayers increase more or less, while those of WC-8Co cemented carbide substrates adjacent to the two interlayers decrease. The WC-8Co/SAE1045 joints using pure Cu and Ag-28Cu alloy as filler metals obtain average shear strength values of about 172 and 136 MPa, and both of the joint fractures occur in the interlayers.

  2. In situ analysis of Refractory Metal Nuggets in carbonaceous chondrites

    Science.gov (United States)

    Daly, Luke; Bland, Phil A.; Dyl, Kathryn A.; Forman, Lucy V.; Evans, Katy A.; Trimby, Patrick W.; Moody, Steve; Yang, Limei; Liu, Hongwei; Ringer, Simon P.; Ryan, Christopher G.; Saunders, Martin

    2017-11-01

    Micrometre to sub-micrometre-scale alloys of platinum group elements (PGEs) known as Refractory Metal Nuggets (RMNs) have been observed in primitive meteorites. The Australian Synchrotron X-ray Fluorescence (XRF) beamline, in tandem with the Maia detector, allows rapid detection of PGEs in concentrations as low as 50-100 ppm at 2 μm resolution. Corroborating these analyses with traditional electron microscopy techniques, RMNs can be rapidly identified in situ within carbonaceous chondrites. These results dispute the assumption of most previous studies: that RMNs are unique to Ca-Al-rich inclusions (CAIs). We find that RMNs are, in fact, observed within all components of carbonaceous chondrites, such as the matrix, chondrules (consistent with observations from Schwander et al. (2015b) and Wang et al. (2007)), and sulphides; though the majority of RMNs are still found in CAIs. The chemistry of RMNs reveals a complex diversity of compositions, which nevertheless averages to CI chondrite abundance ratios. This implies that RMNs are the dominant, if not sole host phase for PGEs. One hundred and thirteen RMNs from this study are combined with reported compositions in the literature, and compared to condensation model compositions similar to Berg et al. (2009), RMNs derived experimentally by precipitation (Schwander et al., 2015a), host phase and host meteorite. Comparisons reveal only weak correlations between parent body processes (sulphidation) and nebular processes (condensation and precipitation) with RMN compositions. It appears that none of these processes acting in isolation or in tandem can explain the diversity observed in the RMN population. Our interpretation is that the Solar Nebula inherited an initially compositionally diverse population of RMNs from the Giant Molecular Cloud; that a variety of Solar System processes have acted on that population; but none have completely homogenised it. Most RMNs have experienced disk and asteroidal processing, but some

  3. Fabrication of Metallic Glass Powder for Brazing Paste for High-Temperature Thermoelectric Modules

    Science.gov (United States)

    Seo, Seung-Ho; Kim, Suk Jun; Lee, Soonil; Seo, Won-Seon; Kim, Il-Ho; Choi, Soon-Mok

    2017-11-01

    Metallic glass (MG) offers the advantage of outstanding oxidation resistance, since it has disordered atomic-scale structure without grain boundaries. We fabricated Al-based MG ribbons (Al84.5Y10Ni5.5) by a melt spinning process. We evaluated the adhesion strength of interfaces between the Al-based MG and a Ni-coated Cu electrode formed under various conditions at high temperature. In addition, we attempted to optimize the process conditions for pulverizing MG ribbons to < 100 micrometers by combining high-energy ball milling and planetary milling. We confirmed that the electrical resistivity of the Al-based MG ribbon was substantially reduced after annealing at high temperature (over 300°C) due to crystallization.

  4. Multifunctional Metallic and Refractory Materials for Energy Efficient Handling of Molten Metals

    Energy Technology Data Exchange (ETDEWEB)

    Xingbo Liu; Ever Barbero; Bruce Kang; Bhaskaran Gopalakrishnan; James Headrick; Carl Irwin

    2009-02-06

    The goal of the project was to extend the lifetime of hardware submerged in molten metal by an order of magnitude and to improve energy efficiency of molten metal handling process. Assuming broad implementation of project results, energy savings in 2020 were projected to be 10 trillion BTU/year, with cost savings of approximately $100 million/year. The project team was comprised of materials research groups from West Virginia University and the Missouri University of Science and Technology formerly University of Missouri – Rolla, Oak Ridge National Laboratory, International Lead and Zinc Research Organization, Secat and Energy Industries of Ohio. Industry partners included six suppliers to the hot dip galvanizing industry, four end-user steel companies with hot-dip Galvanize and/or Galvalume lines, eight refractory suppliers, and seven refractory end-user companies. The results of the project included the development of: (1) New families of materials more resistant to degradation in hot-dip galvanizing bath conditions were developed; (2) Alloy 2020 weld overlay material and process were developed and applied to GI rolls; (3) New Alloys and dross-cleaning procedures were developed for Galvalume processes; (4) Two new refractory compositions, including new anti-wetting agents, were identified for use with liquid aluminum alloys; (5) A new thermal conductivity measurement technique was developed and validated at ORNL; (6) The Galvanizing Energy Profiler Decision Support System (GEPDSS)at WVU; Newly Developed CCW Laser Cladding Shows Better Resistance to Dross Buildup than 316L Stainless Steel; and (7) A novel method of measuring the corrosion behavior of bath hardware materials. Project in-line trials were conducted at Southwire Kentucky Rod and Cable Mill, Nucor-Crawfordsville, Nucor-Arkansas, Nucor-South Carolina, Wheeling Nisshin, California Steel, Energy Industries of Ohio, and Pennex Aluminum. Cost, energy, and environmental benefits resulting from the project

  5. Theory and modeling of active brazing.

    Energy Technology Data Exchange (ETDEWEB)

    van Swol, Frank B.; Miller, James Edward; Lechman, Jeremy B.; Givler, Richard C.

    2013-09-01

    Active brazes have been used for many years to produce bonds between metal and ceramic objects. By including a relatively small of a reactive additive to the braze one seeks to improve the wetting and spreading behavior of the braze. The additive modifies the substrate, either by a chemical surface reaction or possibly by alloying. By its nature, the joining process with active brazes is a complex nonequilibrium non-steady state process that couples chemical reaction, reactant and product diffusion to the rheology and wetting behavior of the braze. Most of the these subprocesses are taking place in the interfacial region, most are difficult to access by experiment. To improve the control over the brazing process, one requires a better understanding of the melting of the active braze, rate of the chemical reaction, reactant and product diffusion rates, nonequilibrium composition-dependent surface tension as well as the viscosity. This report identifies ways in which modeling and theory can assist in improving our understanding.

  6. In Situ Synthesis of Al-Si-Cu Alloy During Brazing Process and Mechanical Property of Brazing Joint

    Directory of Open Access Journals (Sweden)

    LONG Wei-min

    2016-06-01

    Full Text Available The Al-Si-Cu alloy system is considered to be a promising choice of filler metal for aluminium alloys brazing due to its high strength and low melting point. The greatest obstacle is its lack of plastic forming ability and being difficult to be processed by conventional methods. This disadvantage is ascribed to the considerable amount of brittle CuAl2 intermetallic compound which forms when alloy composition is around the ternary eutectic point. In order to overcome this deficiency, authors of this article proposed to synthesize Al-Si-Cu filler metal by using in situ synthesis method, and the structure and properties of brazing joints were studied. The results show that AlSi alloy is used as the wrap layer, and CuAl alloy is used as the powder core in the composite brazing wire, the two alloys have similar melting points. The machinability of the composite brazing wire is much superior to the traditional Al-Si-Cu filler metal. During the induction brazing of 3A21 alloy, when using AlSi-CuAl composite filler wire, AlSi and CuAl alloys melt almost simultaneously, then after short time holding, Al-Si-Cu braze filler is obtained, the brazing seam has uniform composition and good bonding interface, also, the shearing strength of the brazing joints is higher than the joint brazed by conventional Al-Si-Cu filler metal.

  7. The Study of the Impact of Surface Preparation Methods of Inconel 625 and 718 Nickel-Base Alloys on Wettability by BNi-2 and BNi-3 Brazing Filler Metals

    Directory of Open Access Journals (Sweden)

    Lankiewicz K.

    2015-04-01

    Full Text Available The article discusses the impact of surface preparation method of Inconel 625 and 718 nickel-base alloys in the form of sheets on wettability of the surface. The results of the investigations of surface preparation method (such as nicro-blasting, nickel plating, etching, degreasing, abrasive blasting with grit 120 and 220 and manually grinding with grit 120 and 240 on spreading of BNi-2 and BNi-3 brazing filler metals, widely used in the aerospace industry in high temperature vacuum brazing processes, are presented. Technological parameters of vacuum brazing process are shown. The macro- and microscopic analysis have shown that nicro-blasting does not bring any benefits of wettability of the alloys investigated.

  8. The Study Of The Impact Of Surface Preparation Methods Of Inconel 625 And 718 Nickel-Base Alloys On Wettability By BNi-2 And BNi-3 Brazing Filler Metals

    Directory of Open Access Journals (Sweden)

    Lankiewicz K.

    2015-06-01

    Full Text Available The article discusses the impact of surface preparation method of Inconel 625 and 718 nickel-base alloys in the form of sheets on wettability of the surface. The results of the investigations of surface preparation method (such as nicro-blasting, nickel plating, etching, degreasing, abrasive blasting with grit 120 and 220 and manually grinding with grit 120 and 240 on spreading of BNi-2 and BNi-3 brazing filler metals, widely used in the aerospace industry in high temperature vacuum brazing processes, are presented. Technological parameters of vacuum brazing process are shown. The macro- and microscopic analysis have shown that nicro-blasting does not bring any benefits of wettability of the alloys investigated.

  9. Structure and properties of transition metal-metalloid glasses based on refractory metals

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, W.L.; Williams, A.R.

    1979-01-01

    The structure and properties of several new transition metal-metalloid (TM/sub 1-x/M/sub x/) metallic glasses based on refractory transition metals (e.g. Mo, W, Ru etc.) have been systemically investigated as a function of composition. The structure of the alloys has been investigated by x-ray diffraction methods and measurements of superconducting properties, electrical resistivity, density, hardness, and mechanical behavior were made. These data are used in developing a novel description of the structure of TM/sub 1-x/M/sub x/ glasses. The experimental evidence suggests that an ideal amorphous phase forms at a specific composition x/sub c/ and that this phase has a well defined atomic short range order. For metallic glasses having x < x/sub c/ (metalloid poor glasses) vacancy-like defects form, which are characterized by the excess volume which they contribute to the glass. Another, as yet unspecified defect appears to form in glasses with x > x/sub c/. This novel picture can explain the variation of many properties of these glasses with metalloid concentration.

  10. High density-high purity graphite prepared by hot isostatic pressing in refractory metal containers

    Science.gov (United States)

    Hoenig, C.L.

    1994-08-09

    Porous graphite in solid form is hot isostatically pressed in a refractory metal container to produce a solid graphite monolith with a bulk density greater than or equal to 2.10 g/cc. The refractory metal container is formed of tantalum, niobium, tungsten, molybdenum or alloys thereof in the form of a canister or alternatively plasma sprayed, chemically vapor deposited, or coated by some other suitable means onto graphite. Hot isostatic pressing at 2,200 C and 30 KSI (206.8 MPa) argon pressure for two hours produces a bulk density of 2.10 g/cc. Complex shapes can be made. 1 fig.

  11. Alumina barrier for vacuum brazing

    Science.gov (United States)

    Beuyukian, C. S.

    1980-01-01

    Heating platens of vacuum-brazing press will not stick to workpiece if aluminum oxide "paper" is interposed. Paper does not disintegrate in press, will not contaminate braze alloy, and helps form smoothly contoured, regular fillet at brazed edges.

  12. Brazed joint properties and microstructure of SCS-6/{beta}21S titanium matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, E.K.; Bird, R.K.; Dicus, D.L. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center

    1995-11-01

    The properties and microstructure of brazed joints of SCS-6 SiC fiber reinforced {beta}21S (Ti-15Mo-2.7Nb-3Al-0.2Si, wt-%) titanium matrix composite (TMC) were investigated. Brazed joint specimens were fabricated from TMC using two different forms of commercially available Ti-15Cu-15Ni braze filler metal. The brazed joint specimens were tested in air at room temperature and 1,500 F (815 C) using overlap tensile shear (OLTS) tests. Metallurgical and fractographic analyses were used to characterize the microstructure, brazing filler metal/TMC interactions, and joint failure modes. The fractographic results indicated that TMC delamination is a dominant failure mode for this type of joint. At room temperature, the TMC brazed joint specimens failed by TMC delamination and TMC tensile failure, with the brazed joint remaining intact. Therefore, the performance of the brazed joint specimens at room temperature is limited by the interlaminar strength of the TMC and not by the braze strength. At 1,500 F, the TMC brazed joint specimens exhibited a combination of delamination and braze shear failure. Thus, the high-temperature performance of the brazed joint specimens may be limited by both the TMC interlaminar properties and the strength of the braze.

  13. PARTITIONING OF THE REFRACTORY METALS, NICKEL AND CHROMIUM, IN COMBUSTION SYSTEMS

    Science.gov (United States)

    The partitioning of nickel (Ni) and Chromium (Cr) in combustion systems was investigated theoretically and experimentally. In comparison to other volatile and semi-volatile metals, both Ni and Cr are usually considered to be refractory (non-volatile). Theoretical predictions ba...

  14. Condensation of refractory metals in asymptotic giant branch and other stellar environments

    Energy Technology Data Exchange (ETDEWEB)

    Schwander, D.; Berg, T.; Schönhense, G.; Ott, U., E-mail: schwandd@uni-mainz.de [Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55128 Mainz (Germany)

    2014-09-20

    The condensation of material from a gas of solar composition has been extensively studied, but less so condensation in the environment of evolved stars, which has been mainly restricted to major compounds and some specific element groups such as the Rare Earth elements. Also of interest, however, are refractory metals like Mo, Ru, Os, W, Ir, and Pt, which may condense to form refractory metal nuggets (RMNs) like the ones that have been found in association with presolar graphite. We have performed calculations describing the condensation of these elements in the outflows of s-process enriched AGB stars as well as from gas enriched in r-process products. While in carbon-rich environments (C > O), the formation of carbides is expected to consume W, Mo, and V (Lodders and Fegley), the condensation sequence for the other refractory metals under these conditions does not significantly differ from the case of a cooling gas of solar composition. The composition in detail, however, is significantly different due to the completely different source composition. Condensation from an r-process enriched source differs less from the solar case. Elemental abundance ratios of the refractory metals can serve as a guide for finding candidate presolar grains among the RMNs in primitive meteorites—most of which have a solar system origin—for confirmation by isotopic analysis. We apply our calculations to the case of the four RMNs found by Croat et al., which may very well be presolar.

  15. Static and dynamic crack toughness of brazed joints of Inconel 718 nickel-base alloy

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, B.Z. (Technion-Israel Inst. of Tech., Haifa); Steffens, H.D.; Englehart, A.H.; Wielage, B.

    1979-10-01

    The crack toughness of brazed joints of Inconel 718 nickel-base alloy was investigated at different strain rates. The brazing filler metal used was BNi5. The results were compared with those obtained on specimens made of the base material. The brazed joints were heat-treated after the brazing process in order to achieve a desirable distribution of the brittle phases in the joint.

  16. Failure Assessment Diagram for Brazed 304 Stainless Steel Joints

    Science.gov (United States)

    Flom, Yory

    2011-01-01

    Interaction equations were proposed earlier to predict failure in Albemet 162 brazed joints. Present study demonstrates that the same interaction equations can be used for lower bound estimate of the failure criterion in 304 stainless steel joints brazed with silver-based filler metals as well as for construction of the Failure Assessment Diagrams (FAD).

  17. Brazed bipolar plates for PEM fuel cells

    Science.gov (United States)

    Neutzler, Jay Kevin

    1998-01-01

    A liquid-cooled, bipolar plate separating adjacent cells of a PEM fuel cell comprising corrosion-resistant metal sheets brazed together so as to provide a passage between the sheets through which a dielectric coolant flows. The brazement comprises a metal which is substantially insoluble in the coolant.

  18. Development of a brazing process for the production of water- cooled bipolar plates made of chromium-coated metal foils for PEM fuel cells

    Science.gov (United States)

    Mueller, M.; Hoehlich, D.; Scharf, I.; Lampke, T.; Hollaender, U.; Maier, H. J.

    2016-03-01

    Beside lithium batteries, PEM fuel cells are the most promising strategy as a power source to achieve the targets for introducing and increasing the usage of electric vehicles. Due to limited space and weight problems, water cooled, metallic bipolar plates in a fuel cell metal stack are preferred in motor vehicles. These plates are stamped metal sheets with a complex structure, interconnected media-tight. To meet the multiple tasks and requirements in use, complex and expensive combinations of materials are currently in use (carbon fiber composites, graphite, gold-plated nickel, stainless and acid resistant steel). The production of such plates is expensive as it is connected with considerable effort or the usage of precious metals. As an alternative, metalloid nitrides (CrN, VN, W2N, etc.) show a high chemical resistance, hardness and a good conductivity. So this material category meets the basic requirements of a top layer. However, the standard methods for their production (PVD, CVD) are expensive and have a slow deposition rate and a lower layer thicknesses. Because of these limitations, a full functionality over the life cycle of a bipolar plate is not guaranteed. The contribution shows the development and quantification of an alternative production process for bipolar plates. The expectation is to get significant advantages from the combination of chromium electrodeposition and thermochemical treatment to form chromium nitrides. Both processes are well researched and suitable for series production. The thermochemical treatment of the chromium layer also enables a process-integrated brazing.

  19. Silver-Copper Oxide Based Reactive Air Braze (RAB) for Joining Yttria-Stabilized Zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Yong Y.; Hardy, John S.; Weil, K. Scott

    2005-03-01

    We are investigating a new method of ceramic-to-metal joining, referred to as reactive air brazing (RAB), as a potential method of sealing ceramic components in high-temperature electrochemical devices. Sessile drop wetting experiments and joint strength testing were conducted using yttria stabilized zirconia (YSZ) substrates and CuO-Ag based air brazes. Results from our studies indicate that the wettability of the braze improves substantially with increasing CuO content, over a compositional range of 1 - 8 mol% CuO, which is accompanied by an increase in the bend strength of the corresponding brazed YSZ joint. The addition of a small amount of TiO2 (0.5 mol%) to the CuO-Ag braze further improves wettability due to the formation of a titanium zirconate reaction product along the braze/substrate interface. However, with one notable exception, the bend strength of these ternary braze joints remained nearly identical to those measured in comparable binary braze joints. SEM analysis conducted on the corresponding fracture surfaces indicated that in the binary braze joints the failure occurs primarily at the braze/YSZ interface. Similarly in the case of the the ternary, TiO2-doped brazes joint failure occurs predominantly along the interface between the braze filler metal and the underlying titanium zirconate reaction layer.

  20. Preliminary Investigations of Joining Technologies for Attaching Refractory Metals to Ni-Based Superalloys

    Science.gov (United States)

    Gould, Jerry E.; Ritzert, Frank J.; Loewenthal, William S.

    2006-01-01

    In this study, a range of joining technologies has been investigated for creating attachments between refractory metal and Ni-based superalloys. Refractory materials of interest include Mo-47%Re, T-111, and Ta-10%W. The Ni-based superalloys include Hastelloy X and MarM 247. During joining with conventional processes, these materials have potential for a range of solidification and intermetallic formation-related defects. For this study, three non-conventional joining technologies were evaluated. These included inertia welding, electro-spark deposition (ESD) welding, and magnetic pulse welding (MPW). The developed inertia welding practice closely paralleled that typically used for the refractory metals alloys. Metallographic investigations showed that forging during inertia welding occurred predominantly on the nickel base alloy side. It was also noted that at least some degree of forging on the refractory metal side of the joint was necessary to achieve consistent bonding. Both refractory metals were readily weldable to the Hastelloy X material. When bonding to the MarM 247, results were inconsistent. This was related to the higher forging temperatures of the MarM 247, and subsequent reduced deformation on that material during welding. ESD trials using a Hastelloy X filler were successful for all material combinations. ESD places down very thin (5- to 10- m) layers per pass, and interactions between the substrates and the fill were limited (at most) to that layer. For the refractory metals, the fill only appeared to wet the surface, with minimal dilution effects. Microstructures of the deposits showed high weld metal integrity with maximum porosity on the order of a few percent. Some limited success was also obtained with MPW. In these trials, only the T-111 tubes were used. Joints were possible for the T-111 tube to the Hastelloy X bar stock, but the stiffness of the tube (resisting collapse) necessitated the use of very high power levels. These power levels

  1. Brazing of Ti to stainless steel under Ar-gas atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Miyazawa, Y.; Sano, Y.; Minoda, Y.; Ariga, T. [Tokai Univ., Kanagawa (Japan); Chang, C.S. [Engineered Materials Solutions, Attleboro (United States); Kanda, K. [Kanto YakinKogyo Co., Kanagawa (Japan); Takahashi, S. [Osaka Univ. (Japan)

    2007-07-01

    Joining technology of CP-Titanium and Titanium alloy is very important for manufacturing field. In that case of titanium brazing, chemical compositions of brazing filler metal and brazing atmosphere are very important. In this study, Ti alloy (Ti-6Al-4V) / Stainless Steel (SUS630, PH stainless steel) were brazed with Ag-based brazing filler metal foil (Ag-Cu eutectic composition) and Ti-based laminated brazing filler metal foil by using continuous type furnace under Ar gas atmosphere containing extremely low oxygen. Laminated filler was fabricated by roll bonding technology. Whole chemical compositions of laminated filler metal used in this study were Ti-15Cu-15Ni and Ti-20Zr-20Cu-20Ni. Brazing condition employed in this study in that case of laminated brazing filler metal was 950 C and 30 min. and brazing conditions employed in this study in that case of Ag-based brazing filler metal were 830C 3min, 830C 30min, 860C 5min and 900C 5min. Joint characteristics were estimated by micro-structural observation at the joint and mechanical properties measurement. Sound joint was obtained in this study according to outside appearance of the specimen and cross-sectional microstructure. (orig.)

  2. Brazing of titanium at temperatures below 800 C: review and prospective applications

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, A.E. [Titanum Brazing, Inc., Columbus (United States); Flom, Y.A. [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

    2007-07-01

    Brazing temperature of conventional Ti-Cu-Ni and Ti-Zr-Cu-Ni filler metals is usually above the {beta}-transus temperature of titanium base metals that hurts mechanical properties of the base metal. Brazing titanium below the {beta}-transus temperature using the Ag-based and Al-based filler metals of various compositions has been evaluated in the review. Some new Al-based filler metals were tested experimentally for joining thin-wall titanium structures. The effect of alloying elements on the aluminum braze alloys, especially for the intermetallic formation in the brazed titanium joints, was examined. Prospective applications of low-temperature brazing of titanium in Aerospace, Aviation, and Electronics are discussed, as well as potential technical solutions to improve mechanical properties of brazed joints. (orig.)

  3. Comparison of Microstructure and Mechanical Properties of Induction and Vacuume Brazed Joint of Titanium Via Copper and Ag-Cu Eutectic Filler Metal / Mikrostruktura I Właściwości Mechaniczne Połączeń Tytanu Lutowanych Indukcyjnie I Próżniowo Z Użyciem Spoiwa Miedzianego I Eutektycznego Ag-Cu

    Directory of Open Access Journals (Sweden)

    Różański M.

    2015-12-01

    Full Text Available This study presents the basic physico-chemical properties and describes the brazeability of titanium. The work contains the results of macro and microscopic metallographic examination as well as the results of strength-related tests of vacuum and induction brazed joints made of Grade 2 technical titanium using the Cu 0.99 and Ag 272 filler metal interlayers and F60T flux intended for titanium brazing in the air atmosphere.

  4. Brazing dissimilar aluminum alloys

    Science.gov (United States)

    Dalalian, H.

    1979-01-01

    Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.

  5. Joining Ceramics By Brazing

    Science.gov (United States)

    Chiaramonte, Francis P.; Sudsina, Michael W.

    1992-01-01

    Certain ceramic materials tightly bond together by brazing with suitable alloys. Enables fabrication of parts of wide variety of shapes from smaller initial pieces of ceramics produced directly in only limited variety of shapes.

  6. Pulsed laser deposition of thin refractory metal nitride films

    Science.gov (United States)

    Fernandez, Manuel; Bereznai, M.; Caricato, A. P.; D'Anna, Emilia; Juhasz, A.; Leggieri, Gilberto; Luches, Armando; Majni, Guiseppe; Martino, Maurizio; Mengucci, Paolo; Nagy, P. M.; Nanai, Laszlo; Toth, Zsolt

    2003-11-01

    We report on the deposition of thin transition metal nitride (TMN) films by ablating Mo, Ta, V and W targets in low-pressure (1, 10 and 100 Pa) nitrogen atmosphere by KrF excimer laser pulses, and on their characterization. The targets were foils of high purity (99.8%). 3" Si(111) wafers wre used as substrates. Film characteristics (composition, crystalline structure, hardness) were studied as a function of N2 pressure, KrF laser fluence (4.5-19 J/cm2), substrate temperature (20-750°C) and target to substrate distance (30-70 mm). Rutherford backscattering spectrometery (RBS) was used to calculate thickness of the films and identification of the composition. TMN films ar formed already at low N2 ambient pressures (1 Pa) and laser fluences (6 J/cm2) on substrates at room temperature. XRD investigations show that films deposited at elevated temperatures are mostly polycrystalline. While Mo, W and Ta nitrides show respectively a γ-Mo2N, β-W2N and δ-TaN phase in almost any deposition condition, vanadium nitride shows a prevalent phase of δ-VN at N2 pressures of 1-10 Pa, while at higher pressures (100 Pa) and at relatively high laser fluences (16-19 J/cm2) the dominant phase is β-V2N. Generally the crystallinity of the films improves by increasing the substrate temperature. Well-crystallinzed films are obtained on substrates heated at 500°C. Surface morphology, microhardness and electrical resistivity of the films are discussed as a function of both the nitrogen pressure and substrate temperature.

  7. Orthodontic silver brazing alloys.

    Science.gov (United States)

    Brockhurst, P J; Pham, H L

    1989-10-01

    Orthodontic silver brazing alloys suffer from the presence of cadmium, excessive flow temperatures, and crevice corrosion on stainless steel. Seven alloys were examined. Two alloys contained cadmium. The lowest flow temperature observed was 629 degrees C for a cadmium alloy and 651 degrees C for two cadmium free alloys. Three alloys had corrosion resistance superior to the other solders. Addition of low melting temperature elements gallium and indium reduced flow temperature in some cases but produced brittleness in the brazing alloy.

  8. Failure Assessment of Stainless Steel and Titanium Brazed Joints

    Science.gov (United States)

    Flom, Yury A.

    2012-01-01

    Following successful application of Coulomb-Mohr and interaction equations for evaluation of safety margins in Albemet 162 brazed joints, two additional base metal/filler metal systems were investigated. Specimens consisting of stainless steel brazed with silver-base filler metal and titanium brazed with 1100 Al alloy were tested to failure under combined action of tensile, shear, bending and torsion loads. Finite Element Analysis (FEA), hand calculations and digital image comparison (DIC) techniques were used to estimate failure stresses and construct Failure Assessment Diagrams (FAD). This study confirms that interaction equation R(sub sigma) + R(sub tau) = 1, where R(sub sigma) and R(sub t u) are normal and shear stress ratios, can be used as conservative lower bound estimate of the failure criterion in stainless steel and titanium brazed joints.

  9. Low-melting-point titanium-base brazing alloys—part 1: Characteristics of two-, three-, and four-component filler metals

    Science.gov (United States)

    Chang, E.; Chen, C.-H.

    1997-12-01

    The melting point, microstructure, phase, and electrochemical behavior of Ti-21Ni-15Cu alloy, together with two-, three-, and four-component low-melting-point titanium-base brazing alloys, are presented in this paper. Five filler metals were selected for the study, in which melting points were measured by differential thermal analysis, phases identified by x-ray diffractometry, and corrosion behaviors tested by potentiodynamic polarization. The experimental results show that the three-component Ti-15Cu-15Ni and the newly developed Ti-21Ni-14Cu alloys exhibit the combination of lower melting point and superior corrosion resistance compared to the two-and four-component titanium alloys, 316L stainless steel, and a Co-Cr-Mo alloy in Hank’s solution at 37 °C. On a short time basis, the presence of Ti2Ni and Ti2Cu intermetallics in the Ti-15Cu-15Ni and Ti-21Ni-14Cu alloys should not be preferentially dissolved in galvanic corrosion with respect to the dissimilar Ti-6Al-4V alloy.

  10. Fast brazing development for the joining of the beryllium armour layer for the ITER first wall panels

    Energy Technology Data Exchange (ETDEWEB)

    Boudot, C. [AREVA NP Technical centre, Porte Magenta, 71200 Le Creusot (France)], E-mail: cecile.boudot@areva.com; Boireau, B. [AREVA NP Technical centre, Porte Magenta, 71200 Le Creusot (France); Lorenzetto, P. [EFDA, Close Support Unit, Boltzmannstr. 2, D-85748 Garching (Germany); Macel, D. [Institut de soudure, 4, boulevard Henri-Becquerel, 57970 Yutz (France)

    2007-10-15

    This paper describes the development of a flat pancake inductor for brazing beryllium tiles on a primary first wall (PFW) panel heat sink as well as the development of the brazing parameters. Two main variables were tested: brazing filler metal on one hand and PVD coating material on beryllium tiles on the other hand. The nickel coating and silver base brazing filler metal was the best couple and obtained shear values higher than 100 MPa. The inductor design and the choice of materials were applied to the brazing of a mock-up for high heat flux testing. Some tiles sustained 1000 cycles at 1.5 MW.

  11. A unique corundum and refractory metal-nugget bearing micrometeorite P117

    Science.gov (United States)

    Rudraswami, N. G.; Reshma, K.; Shyam Prasad, M.

    2017-01-01

    Micrometeorites provide a large range of samples sourced from a wide variety of planetary materials, thereby providing a scope for expanding the known inventory of solar system materials. Here we report the micrometeorite AAS62-34-P117 having the assemblage of corundum, hibonite, unknown Al-rich phases, FeNi metal blebs, sulfide, and phosphate embedded in Al-rich silicate composition, and Pt-group element nuggets dispersed throughout the micrometeorite. Here, we report the presence of corundum in micrometeorites as a major refractory phase with sizes greater than 10 μm. The Al-rich phases have Al2O3 50-70%, such high Al phases are not known from meteoritic components either in chondrules or refractory inclusions. In addition, the Ca content is extremely poor to relate it directly to known refractory inclusions, but is very high in Al. The presence of corundum in Al-rich phases indicates the micrometeorite to be early condensate from solar nebula that later got incorporated into Si-rich materials leading to a transformation that produced the unusual Al-rich and Ca-poor phases different from the average solar composition. The observed texture and mineralogy of the micrometeorite appears to have evolved in a nebular setting that has compositional reservoirs different from those of any known components of meteorites.

  12. Self-brazing Mechanism of Aluminum Alloy at Medium Temperature

    Directory of Open Access Journals (Sweden)

    CHENG Fang-jie

    2018-01-01

    Full Text Available ZnCl2 and SnCl2 were added to the AlF3-CsF eutectic flux, which can be used for connecting aluminum alloy sheet by self-brazing at medium temperature. The influence of the amount of ZnCl2 and SnCl2 and the size of the T-joint area on the interface microstructure and the self-brazing joint mechanical properties was investigated. The interface microstructure, chemical compositions, defects and tensile fractography of the self-brazing joints were analyzed by metallographic microscope, scanning electron microscope and energy dispersive spectroscopy. The results show that the joints are soundly bonded when both the mass fractions of ZnCl2 and SnCl2 are about 4%; the replacement reactions between Zn2+, Sn2+ of flux and Al atoms of base metal occur during brazing, then the liquid metals of Sn and Zn appear, a great degree of Zn which has high solid solution with Al spreads rapidly to the base metal; Sn is distributed along the interface forming a low melting point metal layer with Zn and Al; the brazing of joints with small area can be realized easily; there are a lot of dimples on the fracture surface and the tensile strength of the brazing joint reaches (58±5MPa.

  13. Brazing of titanium-vapor-coated silicon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Santella, M.L. (Oak Ridge National Lab., TN (USA))

    1988-09-01

    A technique for brazing Si{sub 3}N{sub 4} with metallic alloys was evaluated. The process involved vapor coating the ceramic with a 1.0-{mu}-thick layer of titanium before the brazing operation. The coating improved wetting of the Si{sub 3}N{sub 4} surfaces to the extent that strong bonding between the solidified braze filler metal and the ceramic occurred. Braze joints of Si{sub 3}N{sub 4} were made with Ag-Cu, Au-Ni, and Au-Ni-Pd alloys at temperatures of 790{degree}, 970{degree}, and 1,130{degree}C. Silicon nitride specimens were also brazed with a Ag-Cu alloy to the molybdenum alloy TZM, titanium, and A286 steel at 790{degree}C. Residual stresses resulting from mismatch of thermal expansion coefficients between the Si{sub 3}N{sub 4} and the metals caused all of the ceramic-to-metal joints to spontaneously crack in the Si{sub 3}N{sub 4} upon cooling from the brazing temperature.

  14. Improved Assembly for Gas Shielding During Welding or Brazing

    Science.gov (United States)

    Gradl, Paul; Baker, Kevin; Weeks, Jack

    2009-01-01

    An improved assembly for inert-gas shielding of a metallic joint is designed to be useable during any of a variety of both laser-based and traditional welding and brazing processes. The basic purpose of this assembly or of a typical prior related assembly is to channel the flow of a chemically inert gas to a joint to prevent environmental contamination of the joint during the welding or brazing process and, if required, to accelerate cooling upon completion of the process.

  15. Reactive Brazing of Carbon-Carbon Composites to Titanium

    Science.gov (United States)

    Shpargel, Tarah; Singh, M.; Morscher, Gregory; Asthana, Rajiv

    2004-01-01

    The Ti-metal/C-C composite joints were formed by reactive brazing with three commercial brazes, namely, Cu-ABA, TiCuNi, and TiCuSil. The joint microstructures were examined using optical microscopy, and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). The results of the microstructure analysis indicate solute redistribution across the joint and possible metallurgical bond formation via interdiffusion, which led to good wetting and spreading.

  16. Weld-brazing of titanium

    Science.gov (United States)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1974-01-01

    A joining process, designated weld-brazing, which combines resistance spotwelding and brazing has been developed at the NASA Langley Research Center. Resistance spot-welding is employed to position and align the parts and to establish a suitable faying surface gap for brazing; it contributes to the integrity of the joint. Brazing enhances the properties of the joint and reduces the stress concentrations normally associated with spotwelds. Ti-6Al-4V titanium alloy joints have been fabricated using 3003 aluminum braze both in a vacuum furnace and in a retort containing an inert gas environment.

  17. Isotopic analysis of individual refractory metal nuggets using atom probe tomography

    Science.gov (United States)

    Daly, L.; Bland, P.; Schaefer, B. F.; Saxey, D. W.; Reddy, S.; Fougerouse, D.; William, R. D. A.; Forman, L. V.; Trimby, P.; La Fontaine, A.; Yang, L.; Cairney, J.; Ringer, S.

    2016-12-01

    Sub-micrometre metallic alloys of the highly siderophile elements, known as refractory metal nuggets (RMNs), can be found in primitive carbonaceous chondrites. There has been some suggestion that these grains may have a pre-solar origin, however their <1 µm size has meant that isotopic analysis of individual grains has not previously been possible. Atom probe microscopy has sufficient spatial resolution to quantify the isotopic compositions, across the entire mass range, of small sample volumes (<0.02 µm3) with high sensitivity and precision. We present analyses of four individual RMNs from the same refractory inclusion within the ALH 77307 meteorite. The results indicate that these RMNs have significant isotopic deviations from solar relative isotope abundances and therefore preserve a pre-solar isotopic signature. All RMNs exhibit large p-process enrichments in 98Ru and depletions in s-process 186Os. Two RMNs have a similar isotopic signature, suggesting formation in the same stellar environment. This similarity between two RMNs indicates that there may be a significant contribution of material to our solar system from a single source. The other two RMNs are isotopically dissimilar. Finally, three of the RMNs plot on a 187Re -187Os isochron from which we can derive a galactic age of 12.5 Ga ±1.8. To the best of our knowledge this is the first direct determination of the age of the Milky Way through physical analysis of non-solar material.

  18. Effective Third-Order Nonlinearities in Metallic Refractory Titanium Nitride Thin Films

    CERN Document Server

    Kinsey, Nathaniel; Courtwright, Devon; DeVault, Clayton; Bonner, Carl E; Gavrilenko, Vladimir I; Shalaev, Vladimir M; Hagan, David J; Van Stryland, Eric W; Boltasseva, Alexandra

    2015-01-01

    Nanophotonic devices offer an unprecedented ability to concentrate light into small volumes which can greatly increase nonlinear effects. However, traditional plasmonic materials suffer from low damage thresholds and are not compatible with standard semiconductor technology. Here we study the nonlinear optical properties in the novel refractory plasmonic material titanium nitride using the Z scan method at 1550 nm and 780 nm. We compare the extracted nonlinear parameters for TiN with previous works on noble metals and note a similarly large nonlinear optical response. However, TiN films have been shown to exhibit a damage threshold up to an order of magnitude higher than gold films of a similar thickness, while also being robust, cost-efficient, bio- and CMOS compatible. Together, these properties make TiN a promising material for metal-based nonlinear optics.

  19. Microstructure and Mechanical Properties of Wide-gap Brazed Joints of K465 Alloy Using Cobalt-base Brazing Alloy

    Directory of Open Access Journals (Sweden)

    PAN Hui

    2017-06-01

    Full Text Available Vacuum brazing of K465 superalloy was carried out by using Co45NiCrWB cobalt-base filler metal at 1220 ℃ for different holding time, and the joint clearance was 0.5 mm pre-filled with FGH95 nickel-base superalloy powder. The effect of the structural constitution of brazed different holding time of temperature on the brazed joint microstructure and properties. The results show that the brazing seam is composed of alloy powder particles and borides among them. It is two-phase structure of γ and γ' with a few small blocks of borides in the powder particles, and there exists phases rich in Cr, W and Nb elements. The powder particles are growing along the holding time during the brazing process, while their combination is expanded. It is good for stress rapture properties of joints that borides was fine in brazing seam with more superalloy powder and proper holding time. And the joints brazed for 30-60 min show higher stress rapture properties.

  20. Microgalvanic Corrosion Behavior of Cu-Ag Active Braze Alloys Investigated with SKPFM

    Directory of Open Access Journals (Sweden)

    Armen Kvryan

    2016-04-01

    Full Text Available The nature of microgalvanic couple driven corrosion of brazed joints was investigated. 316L stainless steel samples were joined using Cu-Ag-Ti and Cu-Ag-In-Ti braze alloys. Phase and elemental composition across each braze and parent metal interface was characterized and scanning Kelvin probe force microscopy (SKPFM was used to map the Volta potential differences. Co-localization of SKPFM with Energy Dispersive Spectroscopy (EDS measurements enabled spatially resolved correlation of potential differences with composition and subsequent galvanic corrosion behavior. Following exposure to the aggressive solution, corrosion damage morphology was characterized to determine the mode of attack and likely initiation areas. When exposed to 0.6 M NaCl, corrosion occurred at the braze-316L interface preceded by preferential dissolution of the Cu-rich phase within the braze alloy. Braze corrosion was driven by galvanic couples between the braze alloys and stainless steel as well as between different phases within the braze microstructure. Microgalvanic corrosion between phases of the braze alloys was investigated via SKPFM to determine how corrosion of the brazed joints developed.

  1. Dissimilar Brazed Joints Between Steel and Tungsten Carbide

    Science.gov (United States)

    Voiculescu, I.; Geanta, V.; Binchiciu, H.; Iovanas, D.; Stefanoiu, R.

    2017-06-01

    Brazing is a joining process used to obtain heterogeneous assemblies between different materials, such as steels, irons, non-ferrous metals, ceramics etc. Some application, like asphalt cutters, require quick solutions to obtain dissimilar joints at acceptable costs, given the very short period of operation of these parts. This paper presents some results obtained during the brazing of dissimilar joints between steel and tungsten carbide by using different types of Ag-Cu system filler materials alloyed with P and Sn. The brazing techniques used were oxygen-gas flame and induction joining. The brazing behaviour was analysed in cross sections by optical and electron microscopy. The metallographic analysis enhanced the adhesion features and the length of penetration in the joining gap. The melting range of the filler materials was measured using thermal analysis.

  2. Investigation of a broadband refractory metal metamaterial absorber at terahertz frequencies.

    Science.gov (United States)

    Hu, Dan; Wang, Hongyan; Tang, Zhenjie; Zhang, Xiwei

    2016-07-01

    A broadband, polarization-independent, and wide-angle refractory metal metamaterial absorber is numerically investigated at terahertz frequencies, which consists of a periodic array of a chromium metallic loop and a chromium metallic film separated by a polyimide layer. Results show that a higher than 90% broadband absorption can be achieved for the range of frequencies from 1.00 through 2.43 THz, and the full absorption width at half-maximum can attain 110.80%, which is considerably larger than in previously reported results. Moreover, the greater than 90% broadband absorption response can still be maintained when the incidence angle increases to 45°. The physical origin of the proposed broadband absorber originates from localized surface plasmon resonances of the single metallic loop resonator. Furthermore, the designed concept also can be achieved in the visible and near-infrared region by rationally designing the dimensions of the absorber. This compact design has potential applications in stealth technology, energy harvesting, and thermal imaging.

  3. Brazing of Stainless Steel to Yttria-Stabilized Zirconia Using Gold-Based Brazes for Solid Oxide Fuel Cell Applications

    Science.gov (United States)

    Singh, M.; Shpargel, T. P.; Asthana, R.

    2007-01-01

    Two gold-base active metal brazes (gold-ABA and gold-ABA-V) were evaluated for oxidation resistance to 850 C, and used to join yttria-stabilized zirconia (YSZ) to a corrosion-resistant ferritic stainless steel for possible use in solid oxide fuel cells. Thermogravimetric analysis and optical microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy were used to evaluate the braze oxidation behavior, and microstructure and composition of the YSZ/braze/steel joints. Both gold-ABA and gold-ABA-V exhibited nearly linear oxidation kinetics at 850 C, with gold-ABA-V showing faster oxidation than gold-ABA. Both brazes produced metallurgically sound YSZ/steel joints due to chemical interactions of Ti and V with the YSZ and steel substrates.

  4. Efficacy of Self-Expandable Metallic Stent Inserted for Refractory Hemorrhage of Duodenal Cancer

    Directory of Open Access Journals (Sweden)

    Takashi Orii

    2016-05-01

    Full Text Available Because of advances in the technology of gastrointestinal endoscopy and improvements in the quality of stents, it has become routine to place a stent as palliative therapy for malignant gastrointestinal obstruction. On the other hand, stent placement for malignant gastrointestinal hemorrhage has scarcely been reported, although it may be performed for hemorrhage of the esophageal varicose vein. We recently experienced a patient with refractory hemorrhage from an unresectable duodenal cancer who underwent placement of a self-expandable metallic stent (SEMS and thereafter had no recurrence of the hemorrhage. A 46-year-old man underwent laparotomy to radically resect a cancer in the third portion of the duodenum, which invaded widely to the superior mesenteric vein and its branches and was considered unresectable. After stomach-partitioning gastrojejunostomy was performed, chemotherapy was initiated according to the regimen of chemotherapy of far advanced gastric cancer. One year and 4 months after induction of chemotherapy, gastrointestinal hemorrhage occurred. Upper gastrointestinal endoscopy revealed the hemorrhage oozing from the duodenal cancer, and endoscopic hemostasis, such as injection of hypertonic saline epinephrine and argon plasma coagulation, was unsuccessful. Twenty days after emergence of the hemorrhage, an endoscopic covered SEMS was placed with confirmation by fluoroscopy. Immediately after placement of the stent, the tarry stool stopped and the anemia ceased to progress. The recurrence of the hemorrhage has not been confirmed without migration of the stent. SEMS is an effective hemostatic procedure for malignant refractory hemorrhage.

  5. Experimental Design for Evaluation of Co-extruded Refractory Metal/Nickel Base Superalloy Joints

    Energy Technology Data Exchange (ETDEWEB)

    ME Petrichek

    2005-12-16

    Prior to the restructuring of the Prometheus Program, the NRPCT was tasked with delivering a nuclear space reactor. Potential NRPCT nuclear space reactor designs for the Prometheus Project required dissimilar materials to be in contact with each other while operating at extreme temperatures under irradiation. As a result of the high reactor core temperatures, refractory metals were the primary candidates for many of the reactor structural and cladding components. They included the tantalum-base alloys ASTAR-811C and Ta-10W, the niobium-base alloy FS-85, and the molybdenum base alloys Moly 41-47.5 Rhenium. The refractory metals were to be joined to candidate nickel base alloys such as Haynes 230, Alloy 617, or Nimonic PE 16 either within the core if the nickel-base alloys were ultimately selected to form the outer core barrel, or at a location exterior to the core if the nickel-base alloys were limited to components exterior to the core. To support the need for dissimilar metal joints in the Prometheus Project, a co-extrusion experiment was proposed. There are several potential methods for the formation of dissimilar metal joints, including explosive bonding, friction stir welding, plasma spray, inertia welding, HIP, and co-extrusion. Most of these joining methods are not viable options because they result in the immediate formation of brittle intermetallics. Upon cooling, intermetallics form in the weld fusion zone between the joined metals. Because brittle intermetallics do not form during the initial bonding process associated with HIP, co-extrusion, and explosive bonding, these three joining procedures are preferred for forming dissimilar metal joints. In reference to a Westinghouse Astronuclear Laboratory report done under a NASA sponsored program, joints that were fabricated between similar materials via explosive bonding had strengths that were directly affected by the width of the diffusion barrier. It was determined that the diffusion zone should not exceed

  6. Refractory Metal Heat Pipe Life Test - Test Plan and Standard Operating Procedures

    Science.gov (United States)

    Martin, J. J.; Reid, R. S.

    2010-01-01

    Refractory metal heat pipes developed during this project shall be subjected to various operating conditions to evaluate life-limiting corrosion factors. To accomplish this objective, various parameters shall be investigated, including the effect of temperature and mass fluence on long-term corrosion rate. The test series will begin with a performance test of one module to evaluate its performance and to establish the temperature and power settings for the remaining modules. The performance test will be followed by round-the-clock testing of 16 heat pipes. All heat pipes shall be nondestructively inspected at 6-month intervals. At longer intervals, specific modules will be destructively evaluated. Both the nondestructive and destructive evaluations shall be coordinated with Los Alamos National Laboratory. During the processing, setup, and testing of the heat pipes, standard operating procedures shall be developed. Initial procedures are listed here and, as hardware is developed, will be updated, incorporating findings and lessons learned.

  7. Vacuum Plasma Spray (VPS) Forming of Solar Thermal Propulsion Components Using Refractory Metals

    Science.gov (United States)

    Zimmerman, Frank R.; Hissam, David A.; Gerrish, Harold P.; Davis, William M.

    1999-01-01

    The Thermal Spray Laboratory at NASA's Marshall Space Flight Center has developed and demonstrated a fabrication technique using Vacuum Plasma Spray (VPS) to form structural components from a tungsten/rhenium alloy. The components were assembled into an absorber cavity for a fully-functioning, ground test unit of a solar then-nal propulsion engine. The VPS process deposits refractory metal onto a graphite mandrel of the desired shape. The mandrel acts as a male mold, forming the required contour and dimensions of the inside surface of the deposit. Tungsten and tungsten/25% rhenium were used in the development and production of several absorber cavity components. These materials were selected for their high temperature (greater than 25000 C [greater than 4530 F]) strength. Each absorber cavity comprises 3 coaxial shells with two, double-helical flow passages through which the propellant gas flows. This paper describes the processing techniques, design considerations, and process development associated with forming these engine components.

  8. Plasma brazing of magnesium- and aluminium-alloys; Plasmaloeten von Magnesium- und Aluminiumlegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Bobzin, K.; Ernst, F.; Roesing, J. [RWTH Aachen (Germany)

    2007-07-01

    The increasing demand for light metals in all fields of industry necessitates the further development of economically efficient and ecologically acceptable brazed joints. Plasma brazing is an interesting alternative to established technologies as it offers the possibility of joining Mg and Al alloys with a thick oxide layer without fluxes and with comparatively low thermal stress of the base material. (orig.)

  9. Welding and Brazing Silicon Carbide

    Science.gov (United States)

    Moore, T. J.

    1986-01-01

    Hot isostatic pressing and conventional furnace brazing effective under right conditions. Study performed showed feasibility of welding SiC using several welding and brazing techniques. Use of SiC improves engine efficiency by allowing increase in operating temperature. SiC successfully hot-pressure-welded at 3,550 degrees F (1,950 degrees C) in argon. Refinements of solid-state welding and brazing procedures used sufficient for some specific industrial applications.

  10. RFQ Vacuum brazing at CERN

    CERN Document Server

    Mathot, S

    2008-01-01

    The aim of this paper is to describe the vacuum brazing procedure used at CERN for the brazing of Radio Frequency Quadrupole (RFQ). The RFQ is made of high precision machined OFE copper pieces assembled together. Vacuum brazing is one of the most promising techniques used to join the individual components leading to vacuum tightness and high precision alignment. The RFQ modules brazed at CERN are made of four 100 or 120 cm long vanes (two major and two minor vanes). Our brazing procedure consists of two steps. The first step involves the brazing of the four vanes in a horizontal position. The second step consists of brazing the vacuum stainless steel flanges to the copper structure in a vertical position. The paper describes the problems encountered with the alignment and the vacuum tightness. The difficulties related to the stress relaxation of the machined copper pieces during the brazing heat treatment are discussed. In addition, the solutions developed to improve the alignment of the brazed RFQ’s are...

  11. Microstructure and properties of an Al-Ti-Cu-Si brazing alloy for SiC-metal joining

    Science.gov (United States)

    Dai, Chun-duo; Ma, Rui-na; Wang, Wei; Cao, Xiao-ming; Yu, Yan

    2017-05-01

    An Al-Ti-Cu-Si solid-liquid dual-phase alloy that exhibits good wettability and appropriate interfacial reaction with SiC at 500-600°C was designed for SiC-metal joining. The microstructure, phases, differential thermal curves, and high-temperature wetting behavior of the alloy were analyzed using scanning electron microscopy, X-ray diffraction analysis, differential scanning calorimetry, and the sessile drop method. The experimental results show that the 76.5Al-8.5Ti-5Cu-10Si alloy is mainly composed of Al-Al2Cu and Al-Si hypoeutectic low-melting-point microstructures (493-586°C) and the high-melting-point intermetallic compound AlTiSi (840°C). The contact angle, determined by high-temperature wetting experiments, is approximately 54°. Furthermore, the wetting interface is smooth and contains no obvious defects. Metallurgical bonding at the interface is attributable to the reaction between Al and Si in the alloy and ceramic, respectively. The formation of the brittle Al4C3 phase at the interface is suppressed by the addition of 10wt% Si to the alloy.

  12. Brazing vacuum ceramic tubes for magnets applications

    Energy Technology Data Exchange (ETDEWEB)

    Bagnato, O.R.; Francisco, R.F. [Laboratorio Nacional de Luz Sincrotron (LNLS), SP (Brazil); Gobbi, A.L. [Laboratorio Nacional de Nanotecbologia (LNNano), SP (Brazil); Falvo, T. [Engecer Ltda, Sao Carlos, SP (Brazil)

    2014-07-01

    Full text: The Sirius Project is an initiative of the Brazilian Synchrotron Light Laboratory - LNLS (CNPEM - MCTI ), for the design, construction and operation of a new synchrotron radiation source 3rd generation, with high brightness and energy of the electrons of 3. 0 GeV. Among many other components, will be built 80 ceramic cameras embedded in specials magnets, whose function is to act to correct the orbit of the electron beam in the storage ring. The ceramic chamber is crucial for this application because this material is transparent to the magnetic field generated in the electro magnet and thus acts directly on the electron beam. The difficulty of these constructive components lies in the fact that, the ceramic components must be attached to metal components will join vacuum chambers that make up the ring, and then must present excellent mechanical and vacuum tight. The process of chemical bonding between the ceramic and metal components is performed by brazing in high vacuum. After brazing, is deposited a film of copper with 7 micrometers thickness. The objective of this paper is to describe the process of film deposition and brazing of copper and the excellent results obtained in the production, mechanical characterization, microstructural and tightness. The results obtained with the process indicate an homogeneous film with high adhesion and electrical resistance near the estimated values??. Tests are being carried out by XPS and SEM techniques for chemical and structural characterization. (author)

  13. Changes in the interface structure and strength of diffusion brazed joints of Al-Si alloy castings

    Energy Technology Data Exchange (ETDEWEB)

    Osawa, T. [Aoyamagakuin Univ., Tokyo (Japan). Coll. of Science and Technology

    1995-06-01

    The diffusion brazing process, which utilizes diffusion between the base metal and the filler metal, has been tried for joining Al-Si alloy castings. If a ternary eutectic Al-Cu-Si alloy system with a lower melting point than the Al-Si system base metal is produced at the braze interface by the diffusion reaction between the base metal and the cooper filler metal, it may be possible to join an Al-Si system alloy casting by the diffusion brazing process, using a ternary eutectic Al-Si-Cu alloy as a filler metal. In this experiment both copper and brass materials were used as preforms. It was clarified that the diffusion brazing process with a copper or brass preform could be used for all hypoeutectic, eutectic and hypereutectic alloys of Al-Si system castings, and that the minimum temperature where the braze interface, showed a liquid phase structure was 530 C for the copper preform and 510 C for the brass preform. The shear strength of the diffusion brazed joint was dependent on the chemical compositions of the base metal, the type of material for the preform, and brazing temperature and time. The maximum strength of the diffusion brazed joint under optimum conditions was 130 to 150 MPa for the base metal of both Al-7Si and Al-12Si alloy castings and 100 to 130 MPa for the base metal of Al-20Si alloy casting.

  14. Utilizing Hilbert-Huang transform in detection some of mechanical properties of the refractory metals

    Science.gov (United States)

    Mohammed, Arshed Abdulhamed; Haris, Sallehuddin Mohamed; Nuawi, Mohd Zaki

    2016-02-01

    This study is one of the first to report on the use of Hilbert-Huang transform (HHT) to determine the modulus of elasticity of a material, which is one of the most important properties of metals. In addition, this study involves an analytical study of the process of transfer of energy, which was represented in the form of intrinsic mode functions (IMFs). Moreover, the distribution of IMFs within the time-frequency-plain was determined by testing eight test specimens. Five test specimens were refractory materials, namely, Ti, Ti6AL4V, Zr, Nb, and Ta, and the other three were non-refractory materials, namely, Al, Brass, and ST4340. The new setup was composed of Mg and involves the use of two piezoelectric transducers, which were used as the emitter and receiver. The setup was designed and implemented in this research based on Mg usage to test the metals. First, a new relationship was derived between the pressure transmission coefficient (PTC) of the transmitted wave (through the emitter-water-test specimen-Mg to the receiver) and the corresponding values of the product of the density (ρ) and the modulus of elasticity (E) for the same test specimen. Another relationship was established between the PTCs and the total energy transmitted at high frequencies. This energy indicates the summation of IMFs that have high frequencies (THIMFs), higher than 10 kHz, can determine E better than TOF for most test specimens. To verify this results, with regard to the second conclusion, a new simulation for this setup was carried out using Simulink in MATLAB. Twelve theoretical tests were done, for high acoustic impedance metals, like Hf, Mo, WNiFe and W in addition to test the same group which was tested experimentally. The results of theoretical tests supported the experimental results except for Nb. Most of the conclusions were obtained through practical results and analytical studies. The results proved that THIMFs can determine the change in the microstructure of the alloys

  15. Examination of nanosecond laser melting thresholds in refractory metals by shear wave acoustics

    Directory of Open Access Journals (Sweden)

    A. Abdullaev

    2017-07-01

    Full Text Available Nanosecond laser pulse-induced melting thresholds in refractory (Nb, Mo, Ta and W metals are measured using detected laser-generated acoustic shear waves. Obtained melting threshold values were found to be scaled with corresponding melting point temperatures of investigated materials displaying dissimilar shearing behavior. The experiments were conducted with motorized control of the incident laser pulse energies with small and uniform energy increments to reach high measurement accuracy and real-time monitoring of the epicentral acoustic waveforms from the opposite side of irradiated sample plates. Measured results were found to be in good agreement with numerical finite element model solving coupled elastodynamic and thermal conduction governing equations on structured quadrilateral mesh. Solid-melt phase transition was handled by means of apparent heat capacity method. The onset of melting was attributed to vanished shear modulus and rapid radial molten pool propagation within laser-heated metal leading to preferential generation of transverse acoustic waves from sources surrounding the molten mass resulting in the delay of shear wave transit times. Developed laser-based technique aims for applications involving remote examination of rapid melting processes of materials present in harsh environment (e.g. spent nuclear fuels with high spatio-temporal resolution.

  16. Examination of nanosecond laser melting thresholds in refractory metals by shear wave acoustics

    Science.gov (United States)

    Abdullaev, A.; Muminov, B.; Rakhymzhanov, A.; Mynbayev, N.; Utegulov, Z. N.

    2017-07-01

    Nanosecond laser pulse-induced melting thresholds in refractory (Nb, Mo, Ta and W) metals are measured using detected laser-generated acoustic shear waves. Obtained melting threshold values were found to be scaled with corresponding melting point temperatures of investigated materials displaying dissimilar shearing behavior. The experiments were conducted with motorized control of the incident laser pulse energies with small and uniform energy increments to reach high measurement accuracy and real-time monitoring of the epicentral acoustic waveforms from the opposite side of irradiated sample plates. Measured results were found to be in good agreement with numerical finite element model solving coupled elastodynamic and thermal conduction governing equations on structured quadrilateral mesh. Solid-melt phase transition was handled by means of apparent heat capacity method. The onset of melting was attributed to vanished shear modulus and rapid radial molten pool propagation within laser-heated metal leading to preferential generation of transverse acoustic waves from sources surrounding the molten mass resulting in the delay of shear wave transit times. Developed laser-based technique aims for applications involving remote examination of rapid melting processes of materials present in harsh environment (e.g. spent nuclear fuels) with high spatio-temporal resolution.

  17. Finding Brazing Voids by Holography

    Science.gov (United States)

    Galluccio, R.

    1986-01-01

    Vibration-induced interference fringes reveal locations of defects. Holographic apparatus used to view object while vibrated ultrasonically. Interference fringes in hologram reveal brazing defects. Holographic technique locates small voids in large brazed joints. Identifies unbrazed regions 1 in. to second power (6 cm to the second power) or less in area.

  18. Brazing in Space: The Next Frontier

    Science.gov (United States)

    Flom, Yury

    2005-01-01

    This viewgraph presentation provides information on the challenges facing mechanically joining objects in space, as well as past, present, and future techniques for brazing. The sections of the presentation include: 1) Why do we need to join components in space; 2) Why brazing? 3) History of brazing in space; 4) Electron beam vacuum brazing; 5) Current effort at GSFC; 6) Future work.

  19. Time-sharing switch for vacuum brazing

    Science.gov (United States)

    Stein, J. A.

    1981-01-01

    Switching unit changes power and cooling-water connections between two vacuum-brazing machines. It allows both units to be powered by single radio-frequency (RF) generator. One machine can be used for brazing while bell jar of other is being evacuated (20 minute process) in preparation for brazing or is being cooled after brazing (10 minute process).

  20. Brazing composite intermetallic TiAl with structural materials

    Energy Technology Data Exchange (ETDEWEB)

    Sevryukov, O.N.; Fedotov, V.T.; Kalin, B.A.; Golikov, M.Y. [MIFI-AMENTO, Moscow (Russian Federation)

    2007-07-01

    The intermetallic alloys based on a titanium aluminide have a high strength, a low specific weight, and a chemical and thermal stability. Owing to a similar combination of physical and chemical properties, the given type of materials can be considered as an alternative to the traditional materials used for the manufacture of units of the thermonuclear reactor first wall. The technology to manufacture samples of composite alloys based on a titanium aluminide intermetallide has been improved in the present work with subsequent tests of brazed joints by thermo cycling tests. To estimate the possibility of using this intermetallic alloy as a structural material, brazed joints of Ti-48at.%Al with bronze and titanium were produced. Brazing was carried out by the STEMET 1202 registered filler metal of the Ti-Cu-Zr-Ni-V-Be system. The distribution of chemical elements in the brazed seam was investigated by X-ray spectrum analysis. It has been found that the distribution of the main and doping elements is sufficiently uniform in the contact zone of the filler metal with brazed materials; inclusions, cracks, and delamination are absent. (orig.)

  1. Wetting evaluation of silver based braze alloys onto zirconia metalized with reactive elements for application in oil well drill bots; Avaliacao do molhamento de ligas de adicao a base de prata sobre zirconia polida e metalizada com elementos ativos para aplicacao em brocas de perfuracao de pocos de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, J.C.; Silva, J.M.; Santos, P.R.F.; Nascimento, R.M.; Martinelli, A.E. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Engenharia de Materiais], Email: jocabuzo@gmail.com; Pimenta, J.S. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica

    2010-07-01

    Drill bits with hard ceramic inserts are often used on drilling operations. The cutting and crushing action of rocks will produce failures in the tricone bits, which are related to wear; total or partial rupture of the drill bit body or even the inserts; thermal shock and corrosion. The research of better drill bits with ceramic inserts thermally more stable and mechanically stronger, will lead to an increase of their lifetime, and so reducing costs of substitution and maintenance. In the present work, some silver based braze alloys were melted onto zirconia YSZ substrates metallized or not with active metals. inside a furnace with vacuum of 10{sup -5} mbar to evaluate the wetting behavior. The system with AgCuTi and the non metallized YSZ ceramic, showed low contact angles and stable interfaces, which may be appropriate for brazing metal/ceramic parts. (author)

  2. The plasma device for the high-heat plasma testing of refractory metals and inventing of new highly porous materials

    Science.gov (United States)

    Budaev, V. P.; Fedorovich, S. D.; Martynenko, Yu V.; Lukashevsky, M. V.; Gubkin, M. K.; Lazukin, A. V.; Karpov, A. V.; Shestakov, E. A.

    2017-11-01

    A unique plasma device has been constructed at the NRU “MPEI” for the study of plasma-surface interaction and the high-heat plasma testing of refractory metals, such as tungsten, molybdenum, steel and other plasma facing materials used in fusion reactor including the ITER. This plasma device is a multi-cusp linear stationary plasma confinement system. It has power-saving characteristics as well as compactness due to the employment of the 8-pole multicusp magnetic field configuration instead of a strong axial magnetic field. Experiments are planned to develop a novel technology for highly porous surface structure of the refractory metal with a pore size and nanofibers of 50 nanometers including tungsten “fuzz”.

  3. Cost Estimate for Molybdenum and Tantalum Refractory Metal Alloy Flow Circuit Concepts

    Science.gov (United States)

    Hickman, Robert R.; Martin, James J.; Schmidt, George R.; Godfroy, Thomas J.; Bryhan, A.J.

    2010-01-01

    The Early Flight Fission-Test Facilities (EFF-TF) team at NASA Marshall Space Flight Center (MSFC) has been tasked by the Naval Reactors Prime Contract Team (NRPCT) to provide a cost and delivery rough order of magnitude estimate for a refractory metal-based lithium (Li) flow circuit. The design is based on the stainless steel Li flow circuit that is currently being assembled for an NRPCT task underway at the EFF-TF. While geometrically the flow circuit is not representative of a final flight prototype, knowledge has been gained to quantify (time and cost) the materials, manufacturing, fabrication, assembly, and operations to produce a testable configuration. This Technical Memorandum (TM) also identifies the following key issues that need to be addressed by the fabrication process: Alloy selection and forming, cost and availability, welding, bending, machining, assembly, and instrumentation. Several candidate materials were identified by NRPCT including molybdenum (Mo) alloy (Mo-47.5 %Re), tantalum (Ta) alloys (T-111, ASTAR-811C), and niobium (Nb) alloy (Nb-1 %Zr). This TM is focused only on the Mo and Ta alloys, since they are of higher concern to the ongoing effort. The initial estimate to complete a Mo-47%Re system ready for testing is =$9,000k over a period of 30 mo. The initial estimate to complete a T-111 or ASTAR-811C system ready for testing is =$12,000k over a period of 36 mo.

  4. Influence of particle bombardment on microstructure and internal stresses of refractory metal suicides on silicon

    Science.gov (United States)

    Hardtke, Ch.; Schilling, W.; Ullmaier, H.

    1991-07-01

    First results on microstructural changes and stress relaxation in thin refractory metal suicide films (TaSi 2 and MoSi 2) caused by particle bombardment are reported. The polycrystalline films had initial tensile stresses of some 10 9 Pa. Exposed to irradiation with Ge ions of 400 keV, both suicides showed a similar stress relaxation behaviour as a function of dose. During room-temperature implantation the initial tensile stress rapidly decreased and turned into compressive stress. Continuous irradiation partly relaxed the compressive stress and resulted in a saturation value of some -10 8 Pa. With increasing implantation temperature, the buildup of compressive stress gradually vanished, leaving only the initial decrease of tensile stress which finally approached zero. Based on microstructural investigations (TEM and X-ray diffraction) it is proposed to explain this behaviour by the combined action of two processes: relaxation of tensile stress by a volume increase due to irradiation-induced amorphization, and Frenkel defect production and relaxation of compressive stress by irradiation-induced densification of amorphous regions and/or Frenkel defect elimination.

  5. Direct Metal Deposition of Refractory High Entropy Alloy MoNbTaW

    Science.gov (United States)

    Dobbelstein, Henrik; Thiele, Magnus; Gurevich, Evgeny L.; George, Easo P.; Ostendorf, Andreas

    Alloying of refractory high entropy alloys (HEAs) such as MoNbTaW is usually done by vacuum arc melting (VAM) or powder metallurgy (PM) due to the high melting points of the elements. Machining to produce the final shape of parts is often needed after the PM process. Casting processes, which are often used for aerospace components (turbine blades, vanes), are not possible. Direct metal deposition (DMD) is an additive manufacturing technique used for the refurbishment of superalloy components, but generating these components from the bottom up is also of current research interest. MoNbTaW possesses high yield strength at high temperatures and could be an alternative to state-of-the-art materials. In this study, DMD of an equimolar mixture of elemental powders was performed with a pulsed Nd:YAG laser. Single wall structures were built, deposition strategies developed and the microstructure of MoNbTaW was analyzed by back scattered electrons (BSE) and energy dispersive X-ray (EDX) spectroscopy in a scanning electron microscope. DMD enables the generation of composition gradients by using dynamic powder mixing instead of pre-alloyed powders. However, the simultaneous handling of several elemental or pre-alloyed powders brings new challenges to the deposition process. The influence of thermal properties, melting point and vapor pressure on the deposition process and chemical composition will be discussed.

  6. Self-propagating high-temperature synthesis brazing for emergency repair

    Science.gov (United States)

    Bai, Yang; Luo, Zhen; Fan, Naifeng; Ao, Sansan

    2011-05-01

    It is of great significance to fast weld and repair damaged parts in electroless and gasless field. So, based on Selfpropagating High-temperature Synthesis (SHS), this paper investigates the SHS brazing of thermit reaction. It is found that the heat obtained by SHS thermit reaction can not melt the base metal, however the silver solder with the melting temperature of 595°C to 605°C can all just melt in the middle of the base metal to achieve SHS brazing. In the experiment, as the surface tension, the molten solder is more likely to wet the slag which is with a larger surface tension, resulting in the poor wettability between solder and base metal. By adding a certain amount of silver brazing flux into the powder can solve the problem of base metal wetting. When the silver brazing flux and the powder are in a ratio of 10:1, solder melt completely, and can be separated with slag, there is a good weld surface. With the increase of silver brazing flux, the slag is more loose and easy to removal. The solder and base metal coating is better. However, with further increase in silver brazing flux, the heat from the reaction reduces, solder can not melt. And with the increase of the powder, the slag and the solder can not be separated. SHS brazing combines the thermit reaction heat with the brazing technology to achieve the low carbon steel welding. Using the heat of thermit reaction to melt the solder then weld the steel can overcome the defects of poor quality of traditional welding which use the reaction products. And the operation is simple. SHS brazing achieve the emergency equipment welding under the condition of no electricity, no gas and equipment.

  7. Carbide braze cladding for titanium components; Auftragloeten von Karbiden fuer Verschleissschutz von Titanbauteilen

    Energy Technology Data Exchange (ETDEWEB)

    Bobzin, K.; Ernst, F.; Roesing, J.; Rojas, Y. [RWTH Aachen (Germany)

    2007-07-01

    The abrasion resistance of pure titanium and titanium alloys is not always sufficient for applications where wear resistance demands play an important roll, especially for systems which involve relative sliding tribosystems such as valves, piping connections, etc. Because of this and due to the increasing interest on light materials for structural purposes, the necessity to develop innovative coating techniques in order to increase lifetime and performance of tools keeps on arising. Surface coatings produced by combining braze filler metal with carbide particles increase surface hardness and wear resistance of pure titanium and titanium alloys, which result to be of considerable interest for many engineering applications. This study shows different composite systems based on silver braze and titanium braze alloys, which were especially designed for commercial titanium alloys. The produced carbide/brazing mixtures were brazed and characterised by means of microscopy and ball-on-disc tests, showing an improvement on the wear resistant properties when compared to titanium. (orig.)

  8. More About Brazing Or Welding NiAl Without Filler

    Science.gov (United States)

    Moore, Thomas J.; Kalinowski, Joseph M.

    1996-01-01

    Two reports present additional information about two processes for joining, brazing, or welding workpieces made of nickel aluminide alloys, without use of filler metal. Joining processes involve uniform heating in vacuum-controlled furnace. Eliminates internal thermal gradients in workpieces joined and greatly reduces tendency toward cracking.

  9. Comparison of brazed joints made with BNi-1 and BNi-7 nickel-base brazing alloys

    Directory of Open Access Journals (Sweden)

    Zorc, Borut

    2000-04-01

    Full Text Available Kinetics of the processes are different with different types of brazing alloys. Precipitation processes in the parent metal close to the brazing gap are of great importance. They control the mechanical properties of the joint area when the brittle eutectic has disappeared from the gap. A comparative study of brazed joints on austenitic stainless alloys made with BNi-7 (Ni-P type and BNi-1 (Ni-Si-B type brazing alloys was made. Brazing alloys containing phosphorus behave in a different manner to those containing boron.

    Las aleaciones de níquel se producen mediante tres sistemas de aleación: Ni-P, Ni-Si y Ni-B. Durante las reacciones metalúrgicas con el metal de base, la eutéctica frágil en la separación soldada puede transformarse en la solución dúctil-sólida con todas aleaciones. La cinética del proceso varía según el tipo de aleación. Los procesos de precipitación en el metal de base cerca de la separación soldada son de mucha importancia, ya que controlan las propiedades mecánicas de la área de unión después de desaparecer la eutéctica frágil de la separación. Se ha hecho un análisis comparativo de uniones soldadas en aleaciones austeníticas inoxidables realizadas con aleaciones BNi-7 (tipo Ni-P y BNi-1 (tipo Ni-Si-B. Las aleaciones que contienen fósforo se comportan de una manera diferente, tanto con el cambio de la eutéctica a la solución sólida, como con los procesos de precipitación en el metal de base cerca de la unión soldada.

  10. Development and Evaluation of Wide Clearance Braze Joints in Gamma Prime Alloys.

    Science.gov (United States)

    1982-03-01

    improve their resistance to the hot corrosive gases of the engine. When such parts suffer service damage, it is necessary to clean them prior to braze...sinter metal is mixed with the braze filler metal and that mixture is placed in and on the cra (ck to be repaired. The repair then takes place in a sinele...joints ire likely to be advantageous on surfaces of three types. The; are: newly cast and buffed, surfaces havinc Sttmospheric corrosion product, and

  11. Crystallography of refractory metal nuggets in carbonaceous chondrites: A transmission Kikuchi diffraction approach

    Science.gov (United States)

    Daly, Luke; Bland, Phil A.; Dyl, Kathryn A.; Forman, Lucy V.; Saxey, David W.; Reddy, Steven M.; Fougerouse, Denis; Rickard, William D. A.; Trimby, Patrick W.; Moody, Steve; Yang, Limei; Liu, Hongwei; Ringer, Simon P.; Saunders, Martin; Piazolo, Sandra

    2017-11-01

    Transmission Kikuchi diffraction (TKD) is a relatively new technique that is currently being developed for geological sample analysis. This technique utilises the transmission capabilities of a scanning electron microscope (SEM) to rapidly and accurately map the crystallographic and geochemical features of an electron transparent sample. TKD uses a similar methodology to traditional electron backscatter diffraction (EBSD), but is capable of achieving a much higher spatial resolution (5-10 nm) (Trimby, 2012; Trimby et al., 2014). Here we apply TKD to refractory metal nuggets (RMNs) which are micrometre to sub-micrometre metal alloys composed of highly siderophile elements (HSEs) found in primitive carbonaceous chondrite meteorites. TKD allows us to analyse RMNs in situ, enabling the characterisation of nanometre-scale variations in chemistry and crystallography, whilst preserving their spatial and crystallographic context. This provides a complete representation of each RMN, permitting detailed interpretation of their formation history. We present TKD analysis of five transmission electron microscopy (TEM) lamellae containing RMNs coupled with EBSD and TEM analyses. These analyses revealed textures and relationships not previously observed in RMNs. These textures indicate some RMNs experienced annealing, forming twins. Some RMNs also acted as nucleation centres, and formed immiscible metal-silicate fluids. In fact, each RMN analysed in this study had different crystallographic textures. These RMNs also had heterogeneous compositions, even between RMNs contained within the same inclusion, host phase and even separated by only a few nanometres. Some RMNs are also affected by secondary processes at low temperature causing exsolution of molybdenite. However, most RMNs had crystallographic textures indicating that the RMN formed prior to their host inclusion. TKD analyses reveal most RMNs have been affected by processing in the protoplanetary disk. Despite this

  12. Analysis on High Temperature Aging Property of Self-brazing Aluminum Honeycomb Core at Middle Temperature

    Directory of Open Access Journals (Sweden)

    ZHAO Huan

    2016-11-01

    Full Text Available Tension-shear test was carried out on middle temperature self-brazing aluminum honeycomb cores after high temperature aging by micro mechanical test system, and the microstructure and component of the joints were observed and analyzed using scanning electron microscopy and energy dispersive spectroscopy to study the relationship between brazing seam microstructure, component and high temperature aging properties. Results show that the tensile-shear strength of aluminum honeycomb core joints brazed by 1060 aluminum foil and aluminum composite brazing plate after high temperature aging(200℃/12h, 200℃/24h, 200℃/36h is similar to that of as-welded joints, and the weak part of the joint is the base metal which is near the brazing joint. The observation and analysis of the aluminum honeycomb core microstructure and component show that the component of Zn, Sn at brazing seam is not much affected and no compound phase formed after high temperature aging; therefore, the main reason for good high temperature aging performance of self-brazing aluminum honeycomb core is that no obvious change of brazing seam microstructure and component occurs.

  13. Ag-Al based air braze for high temperature electrochemical devices

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Yong Y.; Hardy, John S.; Weil, K. Scott

    2007-11-01

    Silver-aluminum based air brazing was attempted using an in-situ alloying and brazing process. In this process, layers of foils of aluminum and silver were laid up between alumina plates in alternating fashion to achieve three target compositions representing Ag, Ag3Al, and Ag2Al phases. Each alloy composition revealed different microstructure, mechanical properties and fracture mechanisms. Joints brazed with foils containing 9.8 at% Al formed a long continuous layer parallel to the direction of the original aluminum foil. The fracture occurred through the interface between this long alumina layer and the braze filler, resulting in low bend strength (6 ~ 12 MPa). Joints containing 26.5 at% Al in the braze filler metal experienced the series of phase transformations, leading to cracks in as-brazed specimens. The fracture initiated through these pre-existing cracks, thus the joint strength observed in these specimens was extremely low. The joints prepared using foils with 35.1 at% Al exhibited a good interface even though interfacial alumina particles formed during air brazing. Crack propagation occurred through the interface between the alumina substrate and in-situ formed interfacial alumina particles or directly through these particles and the best bend strength (46 ~ 52 MPa) among Al-added braze compositions was achieved.

  14. Thermodynamic properties of heavy ion heated refractory metals; Thermodynamische Eigenschaften von schwerionengeheizten hochschmelzenden Metallen

    Energy Technology Data Exchange (ETDEWEB)

    Hug, Alexander

    2011-05-04

    Knowledge of basic physical properties of matter in high-energy-density (HED) states such as the equation-of-state (EOS) is of fundamental importance for various branches of basic and applied physics. However, such matter under extreme conditions of temperature and pressure - also called ''warm dense matter'' (WDM) - can only be generated in dynamic experiments employing the most powerful drivers. At the high temperature experimental area HHT of the GSI Helmholtzzentrum fuer Schwerionenforschung (Darmstadt, Germany), intense beams of energetic heavy ions are used for this purpose. The aim of this work is to study thermophysical properties of refractory metals in hot solid and liquid states by precise temperature measurements. In order to identify the melting plateau and to limit the maximum target temperature to the region of interest, relatively long (one microsecond) bunches of uranium and xenon ions have been used to heat initially solid samples. The intense ion beams were focused on a millimetre spot at the target in order to achieve uniform conditions. The temperature on the target surface was determined by analysing thermal radiation emitted from a 0.03 mm{sup 2} area at five different wavelengths. In order to obtain the physical temperature, one has to measure not only the thermal radiation but also the emissivity, ε(T,λ) of the target surface which is not known ab initio. For this purpose, a set-up for direct target reflection measurement was designed and embedded into the fast multichannel pyrometer system. The reflection signal provides the necessary information about modifications of the target surface properties during the interaction with the ion beam. Beside the pyrometric and reflection measurement set-ups, various hardware and software components of the data acquisition system for the heavy-ion beam driven experiments were substantially enhanced. The emissivity was also obtained by identifying the melting plateau and using the

  15. Brazing titanium to stainless steel

    Science.gov (United States)

    Batista, R. I.

    1980-01-01

    Titanium and stainless-steel members are usually joined mechanically for lack of any other effective method. New approach using different brazing alloy and plating steel member with nickel resolves problem. Process must be carried out in inert atmosphere.

  16. Development of a Cu-Sn based brazing system with a low brazing and a high remelting temperature

    Science.gov (United States)

    Schmieding, M.; Holländer, U.; Möhwald, K.

    2017-03-01

    Objective of the project presented is the development of a joining process for hot working steel components at low brazing temperatures leading to a bond with a much higher remelting temperature. This basically is achieved by the use of a Cu-Sn melt spinning foil combined with a pure Cu foil. During brazing, the Sn content of the foil is decreased by diffusion of Sn into the additional Cu resulting in a homogenious joint with a increased remelting temperature of the filler metal. Within this project specimens were brazed and diffusion annealed in a vacuum furnace at 850 °C varying the processing times (0 - 10 h). The samples prepared were studied metallographically and diffusion profiles of Sn were recorded using EDX line scans. The results are discussed in view of further investigations and envisaged applications.

  17. Uniform-Dead-Weight Brazing

    Science.gov (United States)

    Gaw, William D.

    1991-01-01

    Method of deadweight loading for vacuum-furnace brazing improves quality of joint, increases yield, and reduces costs. In improved method, plates weighted with heavy stainless-steel blocks. Blocks act independently and are immune to distortion. Besides being uniformly distributed, force applied to plates larger and repeatable from one brazing operation to next. Larger blocks used on edges of plates, where more thermal mass needed to reduce differences between temperatures of interior and edge as temperature of furnace varied.

  18. Time-shaped RF brazing

    Science.gov (United States)

    Stein, J. A.; Vannasse, M. A.

    1980-01-01

    One RF generator is controlled from two independent work stations with aid of RF switch and simple control boxes. Brazing may be stopped manually or automatically by external brazing-temperature controller or timer in RF switch housing. Switch is air-operated with water-cooled contacts. If switch loses air pressure, generator stops transmitting power. Time-shared outlet increases utilization and productivity of costly RF generator.

  19. Braze Welding TIG of Titanium and Aluminium Alloy Type Al – Mg

    Directory of Open Access Journals (Sweden)

    Winiowski A.

    2016-03-01

    Full Text Available The article presents the course and the results of technological tests related to TIG-based arc braze welding of titanium and AW-5754 (AlMg3 aluminium alloy. The tests involved the use of an aluminium filler metal (Al99.5 and two filler metals based on Al-Si alloys (AlSi5 and AlSi12. Braze welded joints underwent tensile tests, metallographic examinations using a light microscope as well as structural examinations involving the use of a scanning electron microscope and an X-ray energy dispersive spectrometer (EDS. The highest strength and quality of welds was obtained when the Al99.5 filler metal was used in a braze welding process. The tests enabled the development of the most convenient braze welding conditions and parameters.

  20. Strength testing of Ti-vapor-coated silicon nitride braze joints

    Energy Technology Data Exchange (ETDEWEB)

    Santella, M.L.

    1994-09-01

    Sintered silicon nitride was vacuum brazed to itself at 1130{degree}C with a Au-25Ni-25Pd wt % filler metal. Wetting was obtained by coating the Si{sub 3}N{sub 4} surfaces with titanium prior to brazing by electron beam evaporation. The brazed joints were virtually free of porosity. Metallographic analysis showed that Ti reacted with the Si{sub 3}N{sub 4}, to form a TiN reaction layer during brazing. Small amounts of Si and Ti dissolved in the filler metal layers but they did not appear to influence the mechanical properties of the braze layer. Flexure bars were made from the brazed coupons and tested at room temperature, 600C, 700C, and 800C in air. At 700C and below, fracture of the test bars occurred in the Si{sub 3}N{sub 4}, either near the brazed surfaces or at some distance into the monolithic material. The measured strength of joint specimens decreased slightly with increasing test temperature, and generally exceeded the intrinsic braze filler metal strength in this temperature range. It was also found that lapping the Si{sub 3}N{sub 4}, prior to Ti coating reduced the number of near-surface flaws and produced joints with higher average strength and lower scatter than those left in a ground condition. Specimens tested at 800C had very low strengths, and this behavior was related to the microstructure at the brazed Si{sub 3}N{sub 4} surfaces.

  1. Development of Zn50 Brazing Alloy for Joining Mild Steel to Mild Steel (SAE1018

    Directory of Open Access Journals (Sweden)

    S.C. Nwigbo

    2014-09-01

    Full Text Available This work has developed new brazing alloys for joining mild steel to mild steel (SAE1018 at a lower temperature. The alloys blends and error analysis were done by experimental design software (Design Expert 8.0.7.1. Design of experiments was done by Scheffe quadratic mixture method. The liquidus temperatures were predicted by calculation of phase diagrams of the alloying metals. The brazing alloys were produced by gravity technique and melted using silicon carbide graphite crucible. The quality of the brazing alloys was analyzed by optical microscopy (OM, atomic absorption spectroscopy (AAS and fourier transform infrared spectroscopy (FT-IR. Brazed joints were produced by torch method with a commercial flux. Brazing temperatures (liquidus were tracked by a digital infrared/laser pyrometer. Some mechanical properties studied were tensile strength and hardness. Finally, brazed joints produced from the developed brazing alloys were compared to that produced from muntz brass. Six (6 brazing alloys were successfully developed. Zinc and manganese were the main components, to which were added; 3 to 4 %wt silver and 11 to15 %wt modifying element. The microstructure showed a typical eutectic structure with zinc-rich phase distributed uniformly in the matrix with a combination of different sizes of dendrite, rounded blocks of compounds and hypoeutectic structures. AAS results indicated minimal out-gassing of zinc and FT-IR results indicated very low presence of atmospheric gas. The range of brazing temperature for best results was recorded from 690.90 to 735.10 0C. The joints produced from the developed brazing alloys had acceptable strengths with improved stress-strain behaviour compared to muntz brass.

  2. Low-Gold-Content Brazing Alloys

    Science.gov (United States)

    Brennan, A.; Mckown, R. D.

    1982-01-01

    Two new alloys for brazing at 1,760 degrees to 1,850 degrees F are stronger and have better gap-filling capability. Alloys have lower gold content than other gold brazes for their temperature range and therefore are far less expensive. They are produced in wire, foil, and powder and are excellent for brazing at temperatures where no suitable alloys existed--especially for step brazing copper.

  3. Weld-brazing - a new joining process. [combination resistance spot welding and brazing of titanium alloys

    Science.gov (United States)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1972-01-01

    A joining process designated weld brazing which combines resistance spot welding and brazing has been developed. Resistance spot welding is used to position and align the parts as well as to establish a suitable faying surface gap for brazing. Fabrication is then completed by capillary flow of the braze alloy into the joint. The process has been used successfully to fabricate Ti-6Al-4V titanium alloy joints using 3003 aluminum braze alloy. Test results obtained on single overlap and hat-stiffened structural specimens show that weld brazed joints are superior in tensile shear, stress rupture, fatigue, and buckling than joint fabricated by spotwelding or brazing. Another attractive feature of the process is that the brazed joints is hermetically sealed by the braze material.

  4. Structural Performance of Inconel 625 Superalloy Brazed Joints

    Science.gov (United States)

    Chen, Jianqiang; Demers, Vincent; Cadotte, Eve-Line; Turner, Daniel; Bocher, Philippe

    2017-02-01

    The purpose of this work was to investigate tensile and fatigue behaviors of Inconel 625 superalloy brazed joints after transient liquid-phase bonding process. Brazing was performed in a vacuum furnace using a nickel-based filler metal in a form of paste to join wrought Inconel 625 plates. Mechanical tests were carried out on single-lap joints under various lap distance-to-thickness ratios. The fatigue crack initiation and crack growth modes were examined via metallographic analysis, and the effect of local stress on fatigue life was assessed by finite element simulations. The fatigue results show that fatigue strength and endurance limit increase with overlap distance, leading to a relatively large scatter of results. Fatigue cracks nucleated in the high-stressed region of the weld fillets from brittle eutectic phases or from internal brazing cavities. The present work proposes to rationalize the results by using the local stress at the brazing fillet. When using this local stress, all fatigue-obtained results find themselves on a single S- N curve, providing a design curve for any joint configuration in fatigue solicitation.

  5. Brasagem da zircônia metalizada com titânio à liga Ti-6Al-4V Brazing of metalized zirconia with titanium to Ti-6Al-4V alloy

    Directory of Open Access Journals (Sweden)

    J. S. Pimenta

    2012-06-01

    Full Text Available Zircônia tetragonal estabilizada com ítria foi mecanicamente metalizada com titânio e a condição de molhamento avaliada com as ligas convencionais Ag-28Cu e Au-18Ni. Estas dissolveram o revestimento de titânio para uma completa distribuição deste metal ativo na superfície cerâmica, gerando uma liga ativa in situ e possibilitando adequadas ligações químicas ao metal base na temperatura de união. Os melhores resultados de molhamento foram selecionados para brasagem indireta em forno de alto-vácuo nas juntas ZrO2/Ti-6Al-4V. Testes de detecção de vazamento de gás hélio foram realizados na interface de união das juntas; amostras removidas na seção transversal de juntas estanques foram examinadas por técnicas de análise microestrutural. Formou-se uma camada escura adjacente à cerâmica metalizada, responsável pelo molhamento ocasionado pela liga Ag-28Cu. Entretanto, o uso da liga Au-18Ni resultou em precipitação de intermetálicos e microtrincamento interfacial. Perfis de microdureza através da interface resultante até onde a zircônia mostrou típico escurecimento não indicaram alternância significativa entre medições consecutivas; os resultados dos ensaios de resistência mecânica à flexão-3p foram considerados satisfatórios.Yttria tetragonal zirconia polycrystal was mechanically metallized with titanium and the wetting behavior on the ceramic surface was analyzed using the conventional fillers Ag-28Cu and Au-18Ni. These alloys had dissolved the active metal coating, which acts to zirconia reduction on its surface and promoting suitable chemical bonding to the metallic member. Better wetting results were selected for indirect brazing in a high-vacuum furnace for ZrO2/Ti-6Al-4V simple butt joints. Helium gas leak detection was made at the joints interface; samples were removed from the tight joints cross-section and examined by microstructural analysis techniques and EDX analysis. There was formation of a dark

  6. Experimental investigation of refractory metals in the premelting region during fast heating

    Science.gov (United States)

    Senchenko, V. N.; Belikov, R. S.; Popov, V. S.

    2015-11-01

    This work demonstrates experimental possibility of investigation of high refractory materials around its melting point, particularly in premelting region with high accuracy. In this article authors describe the developed experimental setup based on rapid resistive self-heating of a sample by a large current pulse generated by a capacitor discharge circuit that allow fast pulse interruption by temperature feedback signal. The sample temperature was measured with a two-channel microsecond radiation pyrometer. Preliminary experiments were conducted on tantalum and molybdenum at heating speed of 108 K/s. The method allows investigating thermophysical properties of refractory conductive materials such as melting temperature, melting heat, specific resistivity, specific enthalpy and specific heat capacity in solid and liquid phase, especially in premelting area.

  7. Diffusion Couple Alloying of Refractory Metals in Austenitic and Ferritic/Martensitic Steels

    Science.gov (United States)

    2012-03-01

    23]:   ) Dt4 /(x 2 e Dt4 N t,xC    (2) C(x,t) = concentration (wt%) of refractory element at a given position x from the “film” (taken from...as shown in Figure 21. This slope is then defined via Equation (2) as Dt4 1 m  (3) which can be rearranged to solve for

  8. Researches and studies regarding brazed aluminium alloys microstructure used in aeronautic industry

    Directory of Open Access Journals (Sweden)

    A. Dimitrescu

    2015-04-01

    Full Text Available Brazing is applied to the merge of the pieces which are most required, tensile strength of the solder can reach high values. By brazing there can be assembled pieces of most metals and ferrous and nonferrous alloys, with high melting temperature. This paper presents an analysis of the microstructure of materials from a brazed merge of aluminum alloy L103 which is often used to produce pieces of aeronautical industry. Brazing material was performed using several technologies, and after examination of the microstructure of materials from the merge area it was established as optimal technology the technology which consist of pickling in Aloclene 100 solution with the deposition of filler material on both sides of the base material and the use of spectral acetylene and neutral flame.

  9. Diffusion bonding and brazing of high purity copper for linear collider accelerator structures

    Directory of Open Access Journals (Sweden)

    J. W. Elmer

    2001-05-01

    Full Text Available Diffusion bonding and brazing of high purity copper were investigated to develop procedures for joining precision machined copper components for the Next Linear Collider (NLC. Diffusion bonds were made over a range of temperatures from 400 °C to 1000 °C, under two different loading conditions [3.45 kPa (0.5 psi and 3.45 MPa (500 psi], and on two different diamond machined surface finishes. Brazes were made using pure silver, pure gold, and gold-nickel alloys, and different heating rates produced by both radiation and induction heating. Braze materials were applied by both physical vapor deposition (PVD and conventional braze alloy shims. Results of the diffusion bonding experiments showed that bond strengths very near that of the copper base metal could be made at bonding temperatures of 700 °C or higher at 3.45 MPa bonding pressure. At lower temperatures, only partial strength diffusion bonds could be made. At low bonding pressures (3.45 kPa, full strength bonds were made at temperatures of 800 °C and higher, while no bonding (zero strength was observed at temperatures of 700 °C and lower. Observations of the fracture surfaces of the diffusion bonded samples showed the effects of surface finish on the bonding mechanism. These observations clearly indicate that bonding began by point asperity contact, and flatter surfaces resulted in a higher percentage of bonded area under similar bonding conditions. Results of the brazing experiments indicated that pure silver worked very well for brazing under both conventional and high heating rate scenarios. Similarly, pure silver brazed well for both the PVD layers and the braze alloy shims. The gold and gold-containing brazes had problems, mainly due to the high diffusivity of gold in copper. These problems led to the necessity of overdriving the temperature to ensure melting, the presence of porosity in the joint, and very wide braze joints. Based on the overall findings of this study, a two

  10. An evaluation of brazes for plasma facing component applications from a waste disposal perspective

    Energy Technology Data Exchange (ETDEWEB)

    Parish, T.A. (Texas A M Univ., College Station (USA)); Koski, J.A.

    1989-01-01

    Plasma facing components in fusion devices such as tokamaks must often sustain heat fluxes in the 2 to 40 MW/m{sup 2} range. In this environment, it is essential that armor tiles be affixed to an actively cooled substrate with a minimum of thermal contact resistance. For divertor plates, limiters, beam dumps, and other high-heat-flux components used in fusion devices, low Z armor tiles, such as graphite, or high Z armor tiles, such as tungsten, are often brazed to cooled, highly conductive substrates, such as copper. The brazes that are typically 2 to 3 mils thick are chosen for certain characteristics, including (a) the ability to wet the materials to be joined, (b) braze time and temperature and consequent effects on material properties, and (c) metallurgical considerations, such as the potential formation of intermetallic alloys. The effect, or lack of effect, that the braze filler metal has on the granular structure of the metal substrate (copper) is also a consideration. Brazes will be needed in experimental fusion reactors in order to fasten armor tiles to substrates with minimal thermal contact resistance. Calculations of the activation products formed when candidate brazes are irradiated rule out the use of those containing significant amounts of silver or palladium according to current low-level-waste disposal limits. Some of the brazes that are most promising from a waste-disposal perspective have rather small engineering data bases on which to predicate their performance and may have less advantageous metallurgical characteristics. Investigations are continuing to identify promising armor tile-braze-substrate combinations. 3 refs., 1 tab.

  11. Feasibility study of fluxless brazing cemented carbides to steel

    Science.gov (United States)

    Tillmann, W.; Sievers, N.

    2017-03-01

    One of the most important brazing processes is the joints between cemented carbides and steel for the tool industry such as in rotary drill hammers or saw blades. Even though this technique has already been used for several decades, defects in the joint can still occur and lead to quality loss. Mostly, the joining process is facilitated by induction heating and the use of a flux to enhance the wetting of the filler alloy on the surface of the steel and cemented carbide in an ambient atmosphere. However, although the use of flux enables successful joining, it also generates voids within the joint, which reduces the strength of the connection while the chemicals within the flux are toxic and polluting. In this feasibility study, a fluxless brazing process is used to examine the joint between cemented carbides and steel for the first time. For this, ultrasound is applied during induction heating to enable the wetting between the liquid filler metal and the surfaces of the cemented carbide and steel. The ultrasound generates cavitations within the liquid filler metal, which remove the oxides from the surface. Several filler metals such as a silver based alloy Ag449, pure Zn, and an AlSi-alloy were used to reduce the brazing temperature and to lower the thermal residual stresses within the joint. As a result, every filler metal successfully wetted both materials and led to a dense connection. The ultrasound has to be applied carefully to prevent a damage of the cemented carbide. In this regard, it was observed that single grains of the cemented carbide broke out and remained in the joint. This positive result of brazing cemented carbides to steel without a flux but using ultrasound, allows future studies to focus on the shear strength of these joints as well as the behavior of the thermally induced residual stresses.

  12. Fluxless Brazing of Large Structural Panels

    Science.gov (United States)

    Beuyukian, C. S.

    1982-01-01

    Fluxless brazing is used in fabricating aluminum structural panels that withstand high internal pressure. Aluminum sheet of structural thickness with 4045 aluminum/silicon-braze-alloy cladding is brazed to corrugated "fin stock" having channels 0.001 inch (0.03mm) high by same width. Process is carried out in an inert (argon) atmosphere in a retort furnace. Filler bars are used in some channels to prevent fin stock from collapsing as pressure is applied.

  13. Preliminary results on the development of vacuum brazed joints for cryogenic wind tunnel aerofoil models

    Science.gov (United States)

    Wigley, D. A.; Sandefur, P. G., Jr.; Lawing, P. L.

    1981-01-01

    The results of initial experiments show that high-strength void-free bonds can be formed by vacuum brazing of stainless steels using copper and nickel-based filler metals. In Nitronic 40, brazed joints have been formed with strengths in excess of the yield strength of the parent metal, and even at liquid nitrogen temperatures the excellent mechanical properties of the parent metal are only slightly degraded. The poor toughness of 15-5 P.H. stainless steel at cryogenic temperatures is lowered even further by the presence of the brazed bonds investigated. It is highly unlikely that the technique would be used for any critical areas of aerofoil models intended for low-temperature service. Nevertheless, the potential advantages of this simplified method of construction still have attractions for use at ambient temperatures.

  14. Refractory-Slag-Metal-Inclusion Multiphase Reactions Modeling Using Computational Thermodynamics: Kinetic Model for Prediction of Inclusion Evolution in Molten Steel

    Science.gov (United States)

    Shin, Jae Hong; Chung, Yongsug; Park, Joo Hyun

    2017-02-01

    The refractory-slag-metal-inclusion multiphase reaction model was developed by integrating the refractory-slag, slag-metal, and metal-inclusion elementary reactions in order to predict the evolution of inclusions during the secondary refining processes. The mass transfer coefficient in the metal and slag phase, and the mass transfer coefficient of MgO in the slag were employed in the present multiphase reactions modeling. The "Effective Equilibrium Reaction Zone (EERZ) Model" was basically employed. In this model, the reaction zone volume per unit step for metal and slag phase, which is dependent on the `effective reaction zone depth' in each phase, should be defined. Thus, we evaluated the effective reaction zone depth from the mass transfer coefficient in metal and slag phase at 1873 K (1600 °C) for the desulfurization reaction which was measured in the present study. Because the dissolution rate of MgO from the refractory to slag phase is one of the key factors affecting the slag composition, the mass transfer coefficient of MgO in the ladle slag was also experimentally determined. The calculated results for the variation of the composition of slag and molten steel as a function of reaction time were in good agreement with the experimental results. The MgAl2O4 spinel inclusion was observed at the early to middle stage of the reaction, whereas the liquid oxide inclusion was mainly observed at the final stage of the refining reaction. The content of CaO sharply increased, and the SiO2 content increased mildly with the increasing reaction time, while the content of Al2O3 in the inclusion drastically decreased. Even though there is slight difference between the calculated and measured results, the refractory-slag-metal multiphase reaction model constructed in the present study exhibited a good predictability of the inclusion evolution during ladle refining process.

  15. Cadmium hazard in silver brazing.

    Science.gov (United States)

    Gan, S L; Tan, S H; Pinnagoda, J; Tan, K T

    1995-03-01

    This study evaluates the usage of cadmium-containing silver brazing alloys in Singapore and the potential cadmium hazard from its use. Of the 137 factories which responded to the survey questionnaire, only 28 (20.4%) carried out brazing. Of these, only 7 factories used cadmium-containing filler alloys. One hundred and six out of 123 workers from one of these factories had cadmium-in-blood concentrations exceeding 10 mcg/l. Thirty-one (29.2%) of the workers with excessive cadmium absorption had urinary beta-2 microglobulin levels exceeding 28 mcg/g creat. Workers in the other factories who were intermittently exposed had cadmium-in-blood concentrations of 10 mcg/l and below.

  16. Brazing Alloys Indicate Turbomachinery Temperatures

    Science.gov (United States)

    Schlaff, J. W.

    1985-01-01

    Foils serve as consumable thermometers. Stainless-steel tab with circular window holds brazing-foil sample in place. Tab tacked to object to be tested with capacitive-discharge spot welder operating in range 10 + 1 joules. After measurements, tabs and samples chiseled off, leaving tested object fairly well intact. Technique used on objects made of alloys with iron, nickel, or cobalt as principal ingredients.

  17. Weld-brazing of titanium. [resistance spot welding combined with brazing

    Science.gov (United States)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1973-01-01

    A joining process, designated weld-brazing, which combines resistance spot-welding and brazing has been developed at the NASA Langley Research Center. Resistance spot-welding is employed to position and aline the parts and to establish a suitable faying surface gap for brazing and contributes to the integrity of the joint. Brazing enhances the properties of the joint and reduces the stress concentrations normally associated with spotwelds. Ti-6Al-4V titanium alloy joints have been fabricated using 3003 aluminum braze both in a vaccum furnace and in a retort containing an inert gas environment.

  18. Infrared Brazing of Ti50Ni50 Shape Memory Alloy and Inconel 600 Alloy with Two Ag-Cu-Ti Active Braze Alloys

    Science.gov (United States)

    Shiue, Ren-Kae; Wu, Shyi-Kaan; Yang, Sheng-Hao

    2017-02-01

    Infrared brazing of Ti50Ni50 SMA and Inconel 600 alloy using Cusil-ABA and Ticusil filler metals has been investigated. The joints were dominated by Ag-Cu eutectic with proeutectic Cu in the Cusil-ABA brazed joint and with proeutectic Ag in the Ticusil one. A continuous curved belt composed of a Ni3Ti layer and a (Cu x Ni1- x )2Ti layer formed in the brazed Ti50Ni50/Ticusil/Inconel 600 joint. On the Ti50Ni50 SMA side, an intermetallic layer of (Cu x Ni1- x )2Ti formed in all joints, with x values around 0.81 and 0.47. Layers of (Cu x Ni1- x )2Ti, Ni3Ti, and mixed Ni3Ti and Ni2Cr intermetallics were observed next to the Inconel 600 substrate in the brazed Ti50Ni50/Cusil-ABA/Inconel 600 joint. The maximum shear strengths of the joints using the Cusil-ABA filler metal and the Ticusil filler metal were 324 and 300 MPa, respectively. In the Cusil-ABA brazed joint, cracks with cleavage-dominated fracture propagated along the (Cu x Ni1- x )2Ti interfacial layer next to the Ti50Ni50 SMA substrate. In the Ticusil brazed joint, ductile dimple fracture occurred in the Ag-rich matrix near the Inconel 600 alloy substrate. The absence of a detrimental Ti-Fe-(Cu) layer on the Inconel 600 substrate side can effectively improve the shear strength of the joint.

  19. Braze Welding TIG of Titanium and Aluminium Alloy Type Al – Mg

    OpenAIRE

    Winiowski A.; Majewski D.

    2016-01-01

    The article presents the course and the results of technological tests related to TIG-based arc braze welding of titanium and AW-5754 (AlMg3) aluminium alloy. The tests involved the use of an aluminium filler metal (Al99.5) and two filler metals based on Al-Si alloys (AlSi5 and AlSi12). Braze welded joints underwent tensile tests, metallographic examinations using a light microscope as well as structural examinations involving the use of a scanning electron microscope and an X-ray energy disp...

  20. Effect of Filler and Heat Treatment on the Physical and Mechanical Properties of the Brazed Joint between Carbide Tip and Steel

    Science.gov (United States)

    Winardi, Y.; Triyono; Wijayanta, A. T.

    2017-02-01

    In this study, the effect of filler and heat treatment on the physical and mechanical properties of the brazed joint carbide tip and steel was investigated. Tip carbide YG6 and low carbon steel (SS400) is joining by torch brazing with two filler metals, silver, and copper filler. Heat treatment was performed in induction furnace. Microstructure and shear strength of the brazed joint have been investigated. Many silver filler layer are formed on the surface of the base metal rather then using copper filler. The highest shear strength is achieved using a silver filler metal at temperatur 725°C. The highest shear load is 18.62 kN.

  1. TETIG diagrams - a new way to optimise the design parameters and heat treatment of joints made in high-temperature brazing alloys. [LMFBR

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R. (UKAEA Springfields Nuclear Power Development Labs.)

    1982-12-01

    The applications and problems of brazing are reviewed. Phase studies with the braze filler metal chosen for the LMFBR 9% Cr 1% Mo tube-in-tube joint work (BNi4), are discussed, with special reference to the problem of how to eliminate the centre-line eutectics containing hard, brittle compounds. A TETIG diagram is explained with reference to the variables (1) temperature of brazing operation; (2) time of soaking at temperature; and (3) the gap within the joints. Experiments are reported on brazing specimens of AISI 321 stainless steel, using braze filler metals containing various proportions of boron and silicon as the melting point temperature depressant. TETIG diagrams are constructed and used to predict how to optimize further joints. Micrographs show the effects of the variables on the microstructures.

  2. Protecting brazing furnaces from air leaks

    Science.gov (United States)

    Armenoff, C. T.; Mckown, R. D.

    1980-01-01

    Inexpensive inert-atmosphere shielding protects vacuum brazing-furnace components that are likely to spring leak. Pipefittings, gages, and valves are encased in transparent plastic shroud inflated with argon. If leak develops, harmless argon will enter vacuum chamber, making it possible to finish ongoing brazing or heat treatment before shutting down for repair.

  3. Hand-Controlled Brazing-Paste Dispenser

    Science.gov (United States)

    Gilbert, Jeffrey L.

    1994-01-01

    Hand control proven superior to foot control. Hand-operated switch added to hand-held brazing-alloy-paste dispenser yields improved, more consistent brazing-alloy beads. Dispenser used to apply paste between adjacent tubes in heat exchanger. Switch reliable and safe, and removed and reattached easily.

  4. Compatibility of refractory metals and beryllium with molten Pb-17Li

    Energy Technology Data Exchange (ETDEWEB)

    Feuerstein, H. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany); Graebner, H. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany); Oschinski, J. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany); Horn, S. [Forschungszentrum Karlsruhe GmbH Technik und Umwelt (Germany)

    1996-10-01

    The compatibility of V, Nb, Ta, Mo, W and Re with static eutectic mixture Pb-17Li was investigated experimentally. All these metals are very stable in the eutectic up to 600 C. Dissolution rates as well as solubilities are low. Below 600 C, a chemical reaction zone caused by initiation of an intergranular corrosion was observed. There was a strong isothermal mass transfer to the crucible wall. Diffusion coefficients for vanadium were calculated. They are in the expected range. The behaviour of beryllium is included in this paper for comparison. Diffusion coefficients were determined. In spite of low dissolution rates a strong intergranular corrosion causes destruction of this metal. (orig.).

  5. 46 CFR 56.30-30 - Brazed joints.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Brazed joints. 56.30-30 Section 56.30-30 Shipping COAST... Selection and Limitations of Piping Joints § 56.30-30 Brazed joints. (a) General (refer also to subpart 56.75). Brazed socket-type joints shall be made with suitable brazing alloys. The minimum socket depth...

  6. Corrosion Behavior of MIG Brazed and MIG Welded Joints of Automotive DP600-GI Steel Sheet

    Science.gov (United States)

    Basak, Sushovan; Das, Hrishikesh; Pal, Tapan Kumar; Shome, Mahadev

    2016-12-01

    Galvanized dual-phase steel sheets are extensively used by the auto industry for their corrosion resistance property. Welding by the metal inert gas (MIG) process causes degradation of the steel in the vicinity of the joint due to excessive zinc evaporation. In order to minimize Zn loss, the MIG brazing process has been tried out in lap joint configuration over a heat input range of 136-204 J mm-1. The amount of zinc loss, intermetallic formation and corrosion properties in the joint area has been evaluated for both MIG brazing and MIG welding. Corrosion rate of 21 mm year-1 has been reduced to 2 mm year-1 by adopting MIGB in place MIGW. Impedance study has shown that the corrosion mechanism in base metal, MIG brazed and MIG welded joints is dominated by charge transfer, diffusion and mixed mode control processes, respectively.

  7. Dual-atmosphere tolerance of Ag-CuO-based air braze

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Yong; Hardy, John S.; Weil, Scott [Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

    2007-11-15

    Recently, a new braze filler metal based on the silver-copper oxide system was developed for use in sealing high-temperature, solid-state electrochemical devices such as solid oxide fuel cells. One of the concerns regarding the viability of this joining technique is the long-term stability of silver-based alloys under a high-temperature, dual oxidizing/reducing gas environment. This paper reports on an initial series of exposure experiments that were conducted to characterize the effects of (1) filler metal composition, (2) brazing temperature, and (3) exposure time on the microstructural stability of Ag-CuO-brazed Al{sub 2}O{sub 3}/Al{sub 2}O{sub 3} joints under a prototypic operating environment for an intermediate temperature solid oxide fuel cell stack. In general joints exposed simultaneously to air on one side and hydrogen on the other for short periods of time at 800 {sup circle} C (100 h) showed no signs of degradation with respect to hermeticity or joint microstructure. Samples exposed for longer periods of time (1000 h) displayed some internal porosity, which extends approximately halfway across the joint and is not interconnected. Little effect of the filler metal's composition on its tolerance to dual-atmosphere exposure was observed. However, brazing temperature was found to have a measurable effect. Higher brazing temperature leads to a more extensive formation of an interfacial reaction phase, copper aluminate, which tends to tie up some of the free CuO in the filler metal and minimize the formation of porosity in the air-brazed joints during long-term, dual-atmosphere exposure. The effect is due to the greater chemical stability of the copper aluminate relative to copper oxide. (author)

  8. An Investigation of the Irradiation Swelling Mechanisms in Refractory Metals at High Temperatures.

    Science.gov (United States)

    1985-02-01

    Kratos 1.2 MV high voltage transmission electron microscope, a National Electrostatics 2-MV Tandem type universal ion accelerator , and a Texas Nuclear... Electrostatics Type 2 UDHS 2.0-MV Tandem accelerator is equipped with one internal and two external negative ion sources for helium and metal ions...respectively. The specifications are given in Table VI. Table VI. Specifications of Tandem Accelerator Terminal Voltage 180-2000 kV Charging System 1 pelletron

  9. Refractory metal superalloys: Design of yttrium aluminum garnet passivating niobium alloys

    Science.gov (United States)

    Bryan, David

    A systems-based approach, integrating computational modeling with experimental techniques to approach engineering problems in a time and cost efficient manner, was employed to design a Nb-based refractory superalloy for use at 1300°C. Ashby-type selection criteria for both thermodynamic and kinetic parameters were employed to identify a suitable protective oxide for Nb alloys. Yttrium aluminum garnet (YAG) was selected as the most promising candidate for its excellent combination of desirable properties. The alloy microstructural concept was based upon the gamma - gamma' nickel-based superalloys in which the multifunctional gamma' phase serves as both a creep strengthening dispersion and a source of reactive elements for oxide passivation. Candidate ternary Pd-Y-Al and Pt-Y-Al compounds were fabricated and characterized by XRD and DTA. Of the intermetallics studied, only PtYAl had a high enough melting point (1580°C) for use in an alloy operating at 1300°C. The alloy matrix design was based upon Wahl's extension of Wagner's criterion for protective oxidation, requiring a reduction of the product N ODO/DAl by 5 orders of magnitude relative to binary Nb-Al. A thermodynamic and kinetic analysis identified elements with large oxygen affinities as the most beneficial for reducing the magnitude of the quantity NOD O. Construction of a combined thermodynamic and mobility database identified increased Al solubility as the best approach for increasing D Al. Utilizing the thermodynamic and mobility databases, obtained from a combination of model alloys, oxidation experiments, and first principles calculations, theoretical designs predicted the large changes in solubility and transport parameters were achievable. Several prototype alloys were then fabricated and evaluated via oxidation tests at both 1300°C and 1100°C. YAG formation was demonstrated as part of multicomponent oxide scales in the alloys that exhibited the greatest reduction in oxidation rates. The oxidation

  10. Comprehensive recovery of gold and base-metal sulfide minerals from a low-grade refractory ore

    Science.gov (United States)

    Li, Wen-juan; Liu, Shuang; Song, Yong-sheng; Wen, Jian-kang; Zhou, Gui-ying; Chen, Yong

    2016-12-01

    The comprehensive recovery of small amounts of valuable minerals such as gold and base-metal sulfide minerals from a low-grade refractory ore was investigated. The following treatment strategy was applied to a sample of this ore: gold flotation-gold concentrate leaching-lead and zinc flotation from the gold concentrate leaching residue. Closed-circuit trials of gold flotation yielded a gold concentrate that assayed at 40.23 g·t-1 Au with a recovery of 86.25%. The gold concentrate leaching rate was 98.76%. Two variants of lead-zinc flotation from the residue—preferential flotation of lead and zinc and bulk flotation of lead and zinc—were tested using the middling processing method. Foam from the reflotation was returned to the lead rougher flotation or lead-zinc bulk flotation, whereas middlings from reflotation were discarded. Sulfur concentrate was a byproduct. The combined strategy of flotation, leaching, and flotation is recommended for the treatment of this kind of ore.

  11. Braze alloy spreading on steel

    Science.gov (United States)

    Siewert, T. A.; Heine, R. W.; Lagally, M. G.

    1978-01-01

    Scanning electron microscopy (SEM) and Auger electron microscopy (AEM) were employed to observe elemental surface decomposition resulting from the brazing of a copper-treated steel. Two types of steel were used for the study, stainless steel (treated with a eutectic silver-copper alloy), and low-carbon steel (treated with pure copper). Attention is given to oxygen partial pressure during the processes; a low enough pressure (8 x 10 to the -5th torr) was found to totally inhibit the spreading of the filler material at a fixed heating cycle. With both types of steel, copper treatment enhanced even spreading at a decreased temperature.

  12. Dual atmosphere tolerance of Ag-CuO based air braze

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Yong Y.; Hardy, John S.; Weil, K. Scott

    2007-11-01

    Recently, a new braze filler metal based on the silver-copper oxide system was developed for use in sealing high-temperature, solid-state electrochemical devices such as solid oxide fuel cells. One of the concerns regarding the viability of this joining technique is the long-term stability of silver-based alloys under a high-temperature, dual oxidizing/reducing gas environment. This paper reports on an initial series of exposure experiments that were conducted to characterize the effects of (1) filler metal composition, (2) brazing temperature, and (3) exposure time on the microstructural stability of Ag-CuO brazed Al2O3/Al2O3 joints under a prototypic operating environment for an intermediate temperature solid oxide fuel cell stack. In general joints exposed simultaneously to air on one side and hydrogen on the other for short periods of time at 800°C (100 hrs) showed no signs of degradation with respect to hermeticity or joint microstructure. Samples exposed for longer periods of time (1000 hrs) displayed some internal porosity, which extends approximately halfway across the joint and is not interconnected. Little effect of the filler metal’s composition on its tolerance to dual atmosphere exposure was observed. However brazing temperature was found to have a measurable effect. Higher brazing temperature leads to a more extensive formation of an interfacial reaction phase, copper aluminate, which tends to tie up some of the free CuO in the filler metal and minimize the formation of porosity in the air brazed joints during long-term, dual-atmosphere exposure. The effect is due to the greater chemical stability of the copper aluminate relative to copper oxide.

  13. Influence of Exposure to Multiple Brazing Cycles on the Integrity of OFE Copper Brazed Joints

    Science.gov (United States)

    Ganesh, P.; Sandha, R. S.; Choudhary, R. S.; Nagpure, D. C.; Goswami, S. G.; Dwivedi, Jishnu; Kaul, R.; Singh, B.

    2017-11-01

    A 10 MeV, 5 kW S-band travelling wave electron linear accelerator has been developed at Raja Ramanna Centre for Advanced Technology for industrial applications. The electron accelerating structure is made of oxygen-free electronic (OFE) copper and comprises of fifty-six brazed joints and is fabricated in multiple stages, as per the process and testing requirements. The accelerating structure is often required to be repaired through an additional brazing cycle with the same filler. The present study evaluates possible microstructural and mechanical property degradation of OFE copper brazed joints, as a result of its exposure to multiple brazing cycles. The study was performed on an OFE copper cavity stack brazed assembly, made through a four-stage brazing using BVAg-8 as braze filler. The resultant brazed assembly did not exhibit any leak at a sensitivity of 1 × 10-10 mbar.L/s. The results of the study demonstrate that OFE copper brazements can be safely subjected to an additional brazing cycle without causing significant degradation in its microstructure and strength. However, brazed joint's exposure to any additional brazing cycles results in the formation of voids and cracks due to intergranular penetration of silver, with associated drop in tensile strength from about 210 MPa to about 150-180 MPa. Based on the results of study, it is recommended to qualify the accelerating structure, fabricated through multiple brazing cycles, by a suitable non-destructive technique. The results of the study are important for design, fabrication and maintenance of electron linear accelerator components.

  14. Influence of Exposure to Multiple Brazing Cycles on the Integrity of OFE Copper Brazed Joints

    Science.gov (United States)

    Ganesh, P.; Sandha, R. S.; Choudhary, R. S.; Nagpure, D. C.; Goswami, S. G.; Dwivedi, Jishnu; Kaul, R.; Singh, B.

    2017-10-01

    A 10 MeV, 5 kW S-band travelling wave electron linear accelerator has been developed at Raja Ramanna Centre for Advanced Technology for industrial applications. The electron accelerating structure is made of oxygen-free electronic (OFE) copper and comprises of fifty-six brazed joints and is fabricated in multiple stages, as per the process and testing requirements. The accelerating structure is often required to be repaired through an additional brazing cycle with the same filler. The present study evaluates possible microstructural and mechanical property degradation of OFE copper brazed joints, as a result of its exposure to multiple brazing cycles. The study was performed on an OFE copper cavity stack brazed assembly, made through a four-stage brazing using BVAg-8 as braze filler. The resultant brazed assembly did not exhibit any leak at a sensitivity of 1 × 10-10 mbar.L/s. The results of the study demonstrate that OFE copper brazements can be safely subjected to an additional brazing cycle without causing significant degradation in its microstructure and strength. However, brazed joint's exposure to any additional brazing cycles results in the formation of voids and cracks due to intergranular penetration of silver, with associated drop in tensile strength from about 210 MPa to about 150-180 MPa. Based on the results of study, it is recommended to qualify the accelerating structure, fabricated through multiple brazing cycles, by a suitable non-destructive technique. The results of the study are important for design, fabrication and maintenance of electron linear accelerator components.

  15. Deposition of thin film of titanium on ceramic substrate using the discharge for hollow cathode for Al2O3/Al2O3 indirect brazing

    Directory of Open Access Journals (Sweden)

    Mary Roberta Meira Marinho

    2009-01-01

    Full Text Available Thin films of titanium were deposited onto Al2O3 substrate by hollow cathode discharge method for the formation of a ceramic-ceramic joint using indirect brazing method. An advantage of using this technique is that a relatively small amount of titanium is required for the metallization of the ceramic surface when compared with other conventional methods. Rapidly solidified brazing filler of Cu49Ag45Ce6 in the form of ribbons was used. The thickness of deposited titanium layer and the brazing temperature/time were varied. The quality of the brazed joint was evaluated through the three point bending flexural tests. The brazed joints presented high flexural resistance values up to 176 MPa showing the efficiency of the technique.

  16. Closeout Report for the Refractory Metal Accelerated Heat Pipe Life Test Activity

    Science.gov (United States)

    Martin, J.; Reid, R.; Stewart, E.; Hickman, R.; Mireles, O.

    2013-01-01

    With the selection of a gas-cooled reactor, this heat pipe accelerated life test activity was closed out and its resources redirected. The scope of this project was to establish the long-term aging effects on Mo-44.5%Re sodium heat pipes when subjected to space reactor temperature and mass fluences. To date, investigators have demonstrated heat pipe life tests of alkali metal systems up to .50,000 hours. Unfortunately, resources have not been available to examine the effect of temperature, mass fluence, or impurity level on corrosion or to conduct post-test forensic examination of heat pipes. The key objective of this effort was to establish a cost/time effective method to systematically test alkali metal heat pipes with both practical and theoretical benefits. During execution of the project, a heat pipe design was established, a majority of the laboratory test equipment systems specified, and operating and test procedures developed. Procurements for the heat pipe units and all major test components were underway at the time the stop work order was issued. An extremely important outcome was the successful fabrication of an annular wick from Mo-5%Re screen (the single, most difficult component to manufacture) using a hot isostatic pressing technique. This Technical Publication (TP) includes specifics regarding the heat pipe calorimeter water-cooling system, vendor design for the radio frequency heating system, possible alternative calorimeter designs, and progress on the vanadium equilibration technique. The methods provided in this TP and preceding project documentation would serve as a good starting point to rapidly implement an accelerated life test. Relevant test data can become available within months, not years, and destructive examination of the first life test heat pipe might begin within 6 months of test initiation. Final conclusions could be drawn in less than a quarter of the mission duration for a long-lived, fission-powered, deep space probe.

  17. Testing of the wettability during brazing

    Directory of Open Access Journals (Sweden)

    Alin Asavei

    2008-10-01

    Full Text Available This paper aims to present the process of brazing using laser, with the goal of determining the wettability resulted from the brazing process. For the experimental work there was applied only one type of brasing alloy on two different zinc plated sheets. The results of the experiments carried out revealed that the quality of the zinc layer may lead to different behyaviour of the sample surface during the brazing process. Moreover, there was observed that the obtained contact angle is inversely proportional to the advancing speed of the table from the laser device.

  18. Brazing of SiC using Cu-Si non reactive alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gasse, A.; Chaumat, G. [CEA Centre d`Etudes de Grenoble, 38 (France). Dept. d`Etudes des Materiaux; Rado, C.; Eustathopoulos, N. [Institut National Polytechnique, 38 - Grenoble (France)

    1995-12-31

    Wetting and adherence of filler metals on ceramics used to be achieved with active elements such as titanium. However, sessile drop experiments had already showed that a Cu 24 at % Si alloy has excellent wetting and adherence properties on SiC substrates under high vacuum without any measurable reactivity. Despite this good wetting, incomplete filling of joints was sometimes observed with such alloys in certain brazing experiments. This discrepancy is explained by a detailed analysis of Cu-Si alloy wetting mechanisms on SiC and confirmed by brazing experiments in different geometries. (authors). 8 figs.

  19. The flow stress of high-purity refractory body-centred cubic metals and its modification by atomic defects

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, A. [Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany). Inst. fuer Physik

    1995-11-01

    The strong temperature and strain-rate dependence of the flow stress of high-purity refractory body-centred cubic metals has been shown to be an intrinsic property and is ascribed to a high Peierls barrier of a{sub o} left angle 111 right angle /2 screw dislocations. These barriers are overcome by the formation of kink pairs on the screw dislocations. The paper reports on recent, complete flow-stress data on ultra-high purity Mo crystals obtained by two different experimental techniques. The results are in accord with earlier work of Brunner and Diehl on {alpha}-Fe, who showed that below the so-called knee temperature, T{sub K}, three regimes in the temperature variation of the flow-stress should be distinguished. Two of them are fully accounted for by the same glide mechanism, namely elementary glide steps on {l_brace}211{r_brace} planes. The upper bend separating these two regimes in an inherent feature of the theory of kink-pair formation and does not indicate a change in the glide mechanism. There is strong evidence that the lower bend, separating the range of {l_brace}211{r_brace} elementary glide steps from the low-temperature flow-stress regime, is due to a change in the glide mechanism. It is argued that at the lower bend the screw-dislocation cores undergo a ``first-order phase transition`` from a low-temperature configuration that allows glide of a given screw dislocation on any of its three {l_brace}110{r_brace} glide planes to a high-temperature configuration that can glide only on one definite {l_brace}211{r_brace} plane. Between T{sub K} and the lower-bend temperature, T, bcc metals may show the unique phenomena of alloy and irradiation softening. With regard to the latter phenomenon, Brunner and Diehl distinguish between ``primary`` and ``secondary`` softening. It is shown that alloy softening and the ``secondary irradiation softening`` of bcc metals may be explained by an ``overheating`` of the phase transition in the dislocation core. (orig./WL).

  20. Microstructure evolution and mechanical properties of Ti−22Al−25Nb alloy joints brazed with Ti−Ni−Nb alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Cai, X.Q.; Yang, Z.W., E-mail: tjuyangzhenwen@163.com; Qiu, Q.W.; Wang, D.P.; Liu, Y.C.

    2016-10-01

    Ti{sub 45}Ni{sub 45}Nb{sub 10} (at.%) brazing alloy, fabricated by arc melting, was successfully used to braze Ti−22Al−25Nb (at.%) alloy. The microstructures of Ti{sub 45}Ni{sub 45}Nb{sub 10} brazing alloy and Ti−22Al−25Nb alloy brazed joints were analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), and micro-area X-ray diffraction (XRD). The effects of the brazing parameters on the interfacial microstructure and mechanical properties of the Ti−22Al−25Nb alloy brazed joints were investigated. The results showed that the joint was primarily comprised of two characteristic zones: diffusion zone I and central zone II, and the reaction phases formed in the brazed joint were the B2, O, τ{sub 3}, and Ti{sub 2}Ni phase. The crystal orientation of B2 phase in diffusion zone I was consistent with that in the Ti−22Al−25Nb substrate. The O phase was precipitated from the B2 phase. As the brazing temperature or holding time increased, τ{sub 3} was gradually replaced by the B2 phase, and the Ti{sub 2}Ni phase decreased and ultimately disappeared. The maximum shear strength achieved at room temperature was 318 MPa when the joint was brazed at 1180 °C for 20 min, whereas it was 278 MPa at 650 °C. Crack primarily propagated in the τ{sub 3} compound, which was extremely hard and brittle, and partially traversed the B2 and O phases. - Highlights: • Ti{sub 45}Ni{sub 45}Nb{sub 10} alloy was successfully developed to braze Ti−22Al−25Nb alloy. • Ti−22Al−25Nb alloy was transformed from B2 phase into the O + B2 duplex phase after brazing. • Crystal orientation of B2 in joint was dependent on metal substrate. • Correlation between joint microstructure and mechanical properties was revealed. • Ti−22Al−25Nb brazed joint had excellent ambient and high temperature strength.

  1. Brazing of Stainless Steels to Yttria Stabilized Zirconia (YSZ) for Solid Oxide Fuel Cells

    Science.gov (United States)

    Shpargel, Tarah P.; Needham, Robert J.; Singh, M.; Kung, Steven C.

    2005-01-01

    Recently, there has been a great deal of interest in research, development, and commercialization of solid oxide fuel cells. Joining and sealing are critical issues that will need to be addressed before SOFC's can truly perform as expected. Ceramics and metals can be difficult to join together, especially when the joint must withstand up to 900 C operating temperature of the SOFC's. The goal of the present study is to find the most suitable braze material for joining of yttria stabilized zirconia (YSZ) to stainless steels. A number of commercially available braze materials TiCuSil, TiCuNi, Copper-ABA, Gold-ABA, and Gold-ABA-V have been evaluated. The oxidation behavior of the braze materials and steel substrates in air was also examined through thermogravimetric analysis. The microstructure and composition of the brazed regions have been examined by optical and scanning electron microscopy and EDS analysis. Effect of braze composition and processing conditions on the interfacial microstructure and composition of the joint regions will be presented.

  2. Wetting and spreading behavior of Ti-based brazing filler on Ti64 substrate

    Science.gov (United States)

    Komolafe, Bolarinwa; Mostafa, Ahmad

    2017-06-01

    In this work, wetting behavior of Ti-20Zr-20Cu-20Ni brazing filler on Ti-6Al-4V substrate was studied using sessile drop technique. Effects of the substrate surface roughness, R a of ~0.40 and 0.08 µm, and heating scheme on wetting and spreading of the filler metal were evaluated. The wetting mechanism was investigated by the combination of cooling technique, thermal, compositional, and microstructural analysis. This was performed using a heat-flux DSC and an SEM equipped with EDS. The degree of wetting was evaluated by measuring the apparent dynamic contact angle between the filler drop and substrate surface and by calculating the drop spread ratio. The surface roughness of the substrate was found to have little or no effect on the final apparent contact angle. The wetting behavior of this system showed a reactive nature, because it involves dissolution of the substrate and formation of interfacial layers. Three heating schemes were used in the current study. While the high heating rate of 6.8 °C s-1 was found to limit the metallurgical reaction between the substrate and the brazing filler, in the low heating rate scheme of 1.7 °C s-1, more intense metallurgical reaction occurred between the brazing filler and the substrate. The high heating rate with soaking scheme is recommended for brazing, because it entails extensive spreading and limited metallurgical reaction between the brazing filler and the substrate.

  3. Application of Induction Heating for Brazing Parts of Solar Collectors

    Directory of Open Access Journals (Sweden)

    Kristína Demianová

    2012-01-01

    Full Text Available This paper reports on the application of induction heating for brazing parts of solar collectors made of Al alloys. The tube-flange joint is a part of the collecting pipe of a solar collector. The main task was to design an induction coil for this type of joint, and to select the optimum brazing parameters. Brazing was performed with AlSi12 brazing alloy, and corrosive and non-corrosive flux types were also applied. The optimum brazing parameters were determined on the basis of testing the fabricated brazed joints by visual inspection, by leakage tests, and by macro- and micro-analysis of the joint boundary. The following conditions can be considered to be the best for brazing Al materials: power 2.69 kW,brazing time 24 s, flux BrazeTec F32/80.

  4. Aging Thermal Treatment in the Inconel 725 Brazed Incorporating Tungsten Nanoparticles

    Directory of Open Access Journals (Sweden)

    H. M. Hdz-García

    2016-01-01

    Full Text Available Fractures in blade sections of Inconel 725 were impregnated with tungsten nanoparticles and jointed by the brazing process. In order to evaluate their effect over the microstructure, aging thermal treatments at 750°C for 2, 6, 10, and 14 h were done. BNi-9 was selected as brazing filler metal and was characterized by scanning electron microscopy and X-ray fluorescence. Before brazing, the fractures were impregnated with a mixture of tungsten NPs in ethanol. Measurements of Vickers microhardness showed an increase in the melting zone of samples with aging thermal treatment for 14 h, which is attributed to the precipitation of the γ′ phase with a typical size of ca. 100 nm. Likewise, the tungsten NPs modified the size and morphology of Cr-Ni eutectics into finer and uniformly distributed microstructures.

  5. Bonding Mechanisms and Shear Properties of Alumina Ceramic/Stainless Steel Brazed Joint

    Science.gov (United States)

    Liu, G. W.; Qiao, G. J.; Wang, H. J.; Wang, J. P.; Lu, T. J.

    2011-12-01

    Al2O3 ceramic/stainless steel joints were fabricated by activated molybdenum-manganese (Mo-Mn) sintering metallization plus vacuum brazing using Ag-28 wt.% Cu alloy. The bonding mechanisms including metallization and interfacial bonding were analyzed and discussed by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). Tests were also carried out to examine the influence of brazing on joint shear strength. The metallization mechanisms of glassy phase migration and chemical reaction were confirmed experimentally, while Ni coating was found to play a key role in the joining of metallized ceramic to metal via the Ag-Cu filler layer. As a result of the joining, the average shear strength of the joints exceeds 95 MPa, with the maximum reaching 110 MPa.

  6. Repairs of Damaged Castings Made of Graphitic Cast Iron by Means of Brazing

    Directory of Open Access Journals (Sweden)

    Mičian M.

    2017-09-01

    Full Text Available The article summarizes the theoretical knowledge from the field of brazing of graphitic cast iron, especially by means of conventional flame brazing using a filler metal based on CuZn (CuZn40SnSi – brass alloy. The experimental part of the thesis presents the results of performance assessment of brazed joints on other than CuZn basis using silicone (CuSi3Mn1 or aluminium bronze (CuAl10Fe. TIG electrical arc was used as a source of heat to melt these filler materials. The results show satisfactory brazed joints with a CuAl10Fe filler metal, while pre-heating is not necessary, which favours this method greatly while repairing sizeable castings. The technological procedure recommends the use of AC current with an increased frequency and a modified balance between positive and negative electric arc polarity to focus the heat on a filler metal without melting the base material. The suitability of the joint is evaluated on the basis of visual inspection, mechanic and metallographic testing.

  7. Improved corrosion resistance of aluminum brazing sheet by a post-brazing heat treatment

    NARCIS (Netherlands)

    Norouzi Afshar, F.; Tichelaar, F.D.; Glenn, A. M.; Taheri, P.; Sababi, M.; Terryn, H.A.; Mol, J.M.C.

    2017-01-01

    This work studies the influence of the microstructure on the corrosion mechanism and susceptibility of as-brazed aluminum sheet. Various microstructures are obtained using postbrazing heat treatments developed to enhance the corrosion resistance of an AA4xxx/AA3xxx brazing sheet. The heat

  8. Influence of the brazing parameters on microstructure and mechanical properties of brazed joints of Hastelloy B2 nickel base alloy; Influencia de los parametros de soldeo fuerte en la microestructura y propiedades mecanicas de la union de la aleacion base niquel Hastelloy B2

    Energy Technology Data Exchange (ETDEWEB)

    Sotelo, J. C.; Gonzalez, M.; Porto, E.

    2014-07-01

    A study of the high vacuum brazing process of solid solution strengthened Hastelloy B2 nickel alloy has been done. A first stage of research has focused on the selection of the most appropriate brazing filler metal to the base material and vacuum furnace brazing process. The influence of welding parameters on joint microstructure constituents, relating the microstructure of the joint to its mechanical properties, has been evaluated. Two gaps of 50 and 200 micrometers, and two dwell times at brazing temperature of 10 and 90 minutes were studied. The braze joint mainly consists of the nickel rich matrix, nickel silicide and ternary compounds. Finally, the results of this study have shown the high bond strength for small gaps and increased dwell times of 90 minutes. (Author)

  9. Design of a braze alloy for fast epitaxial brazing of superalloys

    Science.gov (United States)

    Piegert, S.; Laux, B.; Rösier, J.

    2012-07-01

    For the repair of directionally solidified turbine components made of nickel-based superalloys, a new high-temperature brazing method has been developed. Utilising heterogeneous nucleation on the crack surface, the microstructure of the base material can be reproduced, i.e. single crystallinity can be maintained. In contrast to commonly used eutectic braze alloys, such as nickel-boron or nickel-silicon systems, the process is not diffusion controlled but works with a consolute binary base system. The currently applied epitaxial brazing methods rely on isothermal solidification diffusing the melting point depressants into the base material until their concentration is reduced so that the liquid braze solidifies. Contrary, the identified Ni-Mn consolute system enables a temperature driven epitaxial solidification resulting in substantially reduced process duration. The development of the braze alloys was assisted using the CALPHAD software Thermo-Calc. The solidification behaviour was estimated by kinetic calculations with realistic boundary conditions. Finally, the complete system, including braze alloy as well as substrate material, was modelled by means of DICTRA. Subsequently, the thermodynamic properties of the braze alloys were experimentally analysed by DSC measurements. For brazing experiments 300 μm wide parallel gaps were used. Complete epitaxial solidification, i.e. the absence of high-angle grain boundaries, could be achieved within brazing times being up to two orders of magnitude shorter compared to diffusion brazing processes. Theoretically and experimentally evaluated process windows reveal similar shapes. However, a distinct shift has to be stated which can be ascribed to the limited accuracy of the underlying thermodynamic databases.

  10. Improving Casing Integrity by Induction Brazing of Casing Connections

    NARCIS (Netherlands)

    Ernens, Dennis; Hariharan, Hari; van Haaften, Willem Maarten; Pasaribu, Rihard; Jabs, Matthew; McKim, Richard

    2017-01-01

    Brazing technology allows metallurgical joining of dissimilar materials using a filler material. In this paper brazing technology applied to casing connections is presented. The initial application was triggered by challenges with mechanical and pressure integrity after expansion of casing

  11. Tensile strength and corrosion resistance of brazed and laser-welded cobalt-chromium alloy joints.

    Science.gov (United States)

    Zupancic, Rok; Legat, Andraz; Funduk, Nenad

    2006-10-01

    The longevity of prosthodontic restorations is often limited due to the mechanical or corrosive failure occurring at the sites where segments of a metal framework are joined together. The purpose of this study was to determine which joining method offers the best properties to cobalt-chromium alloy frameworks. Brazed and 2 types of laser-welded joints were compared for their mechanical and corrosion characteristics. Sixty-eight cylindrical cobalt-chromium dental alloy specimens, 35 mm long and 2 mm in diameter, were cast. Sixteen specimens were selected for electrochemical measurements in an artificial saliva solution and divided into 4 groups (n=4). In the intact group, the specimens were left as cast. The specimens of the remaining 3 groups were sectioned at the center, perpendicular to the long-axis, and were subsequently rejoined by brazing (brazing group) or laser welding using an X- or I-shaped joint design (X laser and I laser groups, respectively). Another 16 specimens were selected for electrochemical measurements in a more acidic artificial saliva solution. These specimens were also divided into 4 groups (n=4) as described above. Electrochemical impedance spectroscopy and potentiodynamic polarization were used to assess corrosion potentials, breakdown potentials, corrosion current densities, total impedances at lowest frequency, and polarization charge-transfer resistances. The remaining 36 specimens were used for tensile testing. They were divided into 3 groups in which specimen pairs (n=6) were joined by brazing or laser welding to form 70-mm-long cylindrical rods. The tensile strength (MPa) was measured using a universal testing machine. Differences between groups were analyzed using 1-way analysis of variance (alpha=.05). The fracture surfaces and corrosion defects were examined with a scanning electron microscope. The average tensile strength of brazed joints was 792 MPa and was significantly greater (Pcobalt-chromium alloy joints, but strength is

  12. Refractory vasculitis

    NARCIS (Netherlands)

    Rutgers, Bram; Kallenberg, Cees G. M.

    Refractory vasculitis occurs in 4-5% of patients with anti-neutrophil cytoplasmic antibody associated vasculitis (AAV). Differences between therapies used for refractory disease are mostly reflected in the percentages of complete and partial remissions, but also in the number of serious side

  13. Braze Development of Graphite Fiber for Use in Phase Change Material Heat Sinks

    Science.gov (United States)

    Quinn, Gregory; Beringer, Woody; Gleason, Brian; Stephan, Ryan

    2011-01-01

    Hamilton Sundstrand (HS), together with NASA Johnson Space Center, developed methods to metallurgically join graphite fiber to aluminum. The goal of the effort was to demonstrate improved thermal conductance, tensile strength and manufacturability compared to existing epoxy bonded techniques. These improvements have the potential to increase the performance and robustness of phase change material heat sinks that use graphite fibers as an interstitial material. Initial work focused on evaluating joining techniques from four suppliers, each consisting of a metallization step followed by brazing or soldering of one inch square blocks of Fibercore graphite fiber material to aluminum end sheets. Results matched the strength and thermal conductance of the epoxy bonded control samples, so two suppliers were down-selected for a second round of braze development. The second round of braze samples had up to a 300% increase in strength and up to a 132% increase in thermal conductance over the bonded samples. However, scalability and repeatability proved to be significant hurdles with the metallization approach. An alternative approach was pursued which used a nickel braze allow to prepare the carbon fibers for joining with aluminum. Initial results on sample blocks indicate that this approach should be repeatable and scalable with good strength and thermal conductance when compared with epoxy bonding.

  14. Investigation of the effect of contaminations and cleaning processes on the surface properties of brazing surfaces

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Wiesner, S.

    2017-03-01

    The quality of brazed joints is determined by different factors such as the atmosphere and the parameters during brazing as well as the condition of the brazing surfaces. Residues of lubricants used during machining of the components and the subsequent cleaning processes can contaminate the faying surfaces and can hence influence the flow ability of the molten filler metals. Besides their influence on the filler metal flow, the residues can result in the formation of carbonic phases in the joint leading to a possible reduction of the corrosion resistance and the mechanical properties. The first step of the current study with the aim of avoiding these defects is to identify the influence of critical contaminations and cleaning methods on the quality of the brazed joints. In a first step, contaminations on AISI304 and Inconel alloy 625 due to different cooling lubricants and the effect of several cleaning methods, in particular plasma cleaning, have been investigated. Information about the surface energy of contaminated and cleaned surfaces was gained by measuring contact angle of testing fluids. Additionally, the lubricants and the resulting contamination products have been analyzed considering the influence of a heat treatment.

  15. The Effect of Composition on the Wetting Behavior and Joint Strength of the Ag-CuO Reactive Air Braze

    Energy Technology Data Exchange (ETDEWEB)

    Weil, K. Scott; Coyle, Christopher A.; Kim, Jin Yong Y.; Hardy, John S.

    2003-05-15

    One of the challenges in manufacturing solid-state electrochemical devices is in joining the ceramic and metallic components such that the resulting joint is rugged, hermetic, and stable under continuous high temperature operation in an oxidizing atmosphere. A well proven method of joining dissimilar materials is by brazing. Unfortunately many of the commercially available ceramic-to-metal braze alloys exhibit oxidation behavior which is unacceptable for potential use in a high temperature electrochemical device. An alternative braze alloy composition designed for oxidation resistance has been developed to join ferritic stainless steel to a variety of electrochemically active ceramic membranes including YSZ, nickel oxide, and mixed conducting perovskite oxides. The results of this study to date will be discussed.

  16. The Brazing Behavior of Aluminum-Steel Cladding Strip with Pre-Cladded Brazing Layer Used in Air Cooling System of Power Plants

    OpenAIRE

    Sun Chang; Zhang Xiao-jun; Li Long; Zhou De-jing

    2016-01-01

    The brazing behavior of 3003 fin assemble with 4343(filler layer)/4A60(transition layer)/08Al(steel layer) brazing sheet (the ratio of filler layer thickness to transition thickness were constant 1:2) were investigated. This study elucidates the brazing results vary with the layer thickness and brazing temperatures. Results showed that keeping the holding time at brazing temperature constant (the holding time of this study was 10 minutes in all brazing progress), under the condition of brazin...

  17. Experimental fatigue curves for aluminium brazed areas

    Science.gov (United States)

    Dimitescu, A.; Babiş, C.; Niţoi, D. F.; Radu, C.

    2017-08-01

    An important factor for the quality of joints is the brazed area. The fatigue check occupies a major position among many test procedures and methods, especially by the joining technologies. The results of processing the fatigue data experiments for aluminium brazed samples are used to find the regression function and the response surface methodology. The fatigue process of mechanical components under service loading is stochastic in nature. The prediction of time-dependent fatigue reliability is critical for the design and maintenance planning of many structural components.

  18. Braze welding of cobalt with a silver–copper filler

    Directory of Open Access Journals (Sweden)

    Everett M. Criss

    2015-01-01

    Full Text Available A new method of joining cobalt by braze-welding it with a silver–copper filler was developed in order to better understand the residual stresses in beryllium–aluminum/silicon weldments which are problematic to investigate because of the high toxicity of Be. The base and filler metals of this new welding system were selected to replicate the physical properties, crystal structures, and chemical behavior of the Be–AlSi welds. Welding parameters of this surrogate Co–AgCu system were determined by experimentation combining 4-point bending tests and microscopy. Final welds are 5 pass manual TIG (tungsten inert gas, with He top gas and Ar back gas. Control of the welding process produces welds with full penetration melting of the cobalt base. Microscopy indicates that cracking is minimal, and not through thickness, whereas 4-point bending shows failure is not by base-filler delamination. These welds improve upon the original Be–AlSi welds, which do not possess full penetration, and have considerable porosity. We propose that utilization of our welding methods will increase the strength of the Be–AlSi weldments. The specialized welding techniques developed for this study may be applicable not only for the parent Be–AlSi welds, but to braze welds and welds utilizing brittle materials in general. This concept of surrogacy may prove useful in the study of many different types of exotic welds.

  19. Simulation model of Al-Ti dissimilar laser welding-brazing and its experimental verification

    Science.gov (United States)

    Behúlová, M.; Babalová, E.; Nagy, M.

    2017-02-01

    Formation of dissimilar weld joints of light metals and alloys including Al-Ti joints is interesting mainly due to demands on the weight reduction and corrosion resistance of components and structures in automotive, aircraft, aeronautic and other industries. Joining of Al-Ti alloys represents quite difficult problem. Generally, the fusion welding of these materials can lead to the development of different metastable phases and formation of brittle intermetallic compounds. The paper deals with numerical simulation of the laser welding-brazing process of titanium Grade 2 and EN AW 5083 aluminum alloy sheets using the 5087 aluminum filler wire. Simulation model for welding-brazing of testing samples with the dimensions of 50 × 100 × 2 mm was developed in order to perform numerical experiments applying variable welding parameters and to design proper combination of these parameters for formation of sound Al-Ti welded-brazed joints. Thermal properties of welded materials in the dependence on temperature were computed using JMatPro software. The conical model of the heat source was exploited for description of the heat input to the weld due to the moving laser beam source. The sample cooling by convection and radiation to the surrounding air and shielding argon gas was taken into account. Developed simulation model was verified by comparison of obtained results of numerical simulation with the temperatures measured during real experiments of laser welding-brazing by the TruDisk 4002 disk laser.

  20. Gaseous Shielding Gas Additives as Flux Substitute for TIG Arc Brazing

    Directory of Open Access Journals (Sweden)

    Uwe Reisgen

    2015-09-01

    Full Text Available Abstract Brazing is one of the key technologies in the field of joining of metal components. To improve the wetting of brazing material and work-piece surface, it is often required to fall back on the use of flux. The application of these substances requires accuracy and is often connected with considerable expenditure and it is, just as the removal of flux residues, often an additional working step which has to be carried out manually. Within the framework of a DFG research project it has been investigated to which degree gaseous substances as addition to the shielding gas may replace conventional flux in TIG arc brazing. To this end, investigations have been carried out using different combinations of base and filler materials. Mainly monosilane as a gaseous flux substitute has been added in low concentrations to the shielding gas volume flow. The resulting brazed joints have been quantified with regard to their geometry, their fusion conditions and their chemical compositions. These qualities were then correlated and evaluated with the provided quantity of monosilane in order to identify dependencies.

  1. Brazing of zirconia to titanium using Ag-Cu and Au-Ni filler alloys

    Directory of Open Access Journals (Sweden)

    Jean S. Pimenta

    2013-12-01

    Full Text Available Advanced ceramic is usually joined to metal by the well-known direct brazing process, where costly active filler alloys can be considered a limitation. Brazing using active-metal-free filler alloy as insert between the joint components is an attempt to overcome it. The active metal diffusion from the titanium member through the bulk of molten filler to the ceramic was responsible to produce an active filler alloy in loco and promote reduction of the zirconium oxide to improve wetting on the ceramic surface. Unalloyed titanium was joined in a high-vacuum furnace (<3x10-5 mbar to yttria-tetragonal zirconia polycristals (Y-TZP and zirconia partially stabilized with magnesia (Mg-PSZ, where commercial fillers Ag-28Cu and Au-18Ni with respective thermal cycles were evaluated. Helium gas leak detection test was performed at the ceramic/metal interface at room temperature; samples from reliable vacuum tight joints were examined by microstructural analysis techniques and energy dispersive X-ray analysis at the joint cross-section. Tight joints were produced with eutectic Ag-Cu filler, revealing an intermetallic layer and a dark reaction layer near the ceramic surface; titanium diffusion was efficient for superficial chemical interactions between individual components. Brazing joints were also tested using three-point flexure testing.

  2. Investigation of the effect of rapidly solidified braze ribbons on the microstructure of brazed joints

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Wiesner, S.; Rochala, P.; Mayer, J.; Aretz, A.; Iskandar, R.; Schwedt, A.

    2017-03-01

    Shrinkage and warpage due to melting and solidification are crucial for the geometric precision of related components. In order to assure a high geometric precision, the formation of the microstructure in the joint during brazing must be taken into consideration. An extensive interaction can occur between liquid melt and base material, resulting in the formation of distinctive phases. This interaction depends on the parameters of the brazing process. However, the consequences of the interaction between phase formation and process parameters in terms of geometric precision cannot be estimated yet. Insufficient quality of the joint can be a result. In this study, investigations focus on the process of solidification in terms of time dependent diffusion behavior of elements. Therefore, microcrystalline and amorphous braze ribbons based on Ti are produced by rapid solidification and are used for joining. The microstructure of the braze ribbons as well as the melting behavior and phase formation during brazing are considered to be of particular importance for the mechanical properties of the brazed components.

  3. -C Refractories

    Science.gov (United States)

    Xu, Yibiao; Sang, Shaobai; Li, Yawei; Ren, Bo; Zhao, Lei; Li, Yuanbing; Li, Shujing

    2014-06-01

    Al2O3-C refractories were first fabricated in a coke bed at 1673 K (1400 °C) using tabular corundum, reactive alumina, carbon black, silicon, and microsilica as the starting materials and phenol resin as the binder. Then the alkali attack resistance of those materials was conducted in the powder mixture of carbon black and potassium carbonate (1:1 wt pct) in a graphite crucible at 1273 K (1000 °C) for 10 hours. The correlation between pore size, permeability of Al2O3-C refractories, and their alkali (K2CO3) attack was investigated by means of mercury intrusion porosimetry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results showed that the pore structure of Al2O3-C refractories was controlled by the addition of silicon, ultrafine reactive alumina, and microsilica to in-situ form SiC whiskers and mullite in the preparation process. The mean pore size of Al2O3-C refractories was strongly associated with permeability. With the decrease of the mean pore size, the permeability of the Al2O3-C refractories reduced constantly. The alkali attack test also verified that the Al2O3-C refractories with lower permeability had better alkali corrosion resistance, because the penetration of K vapor into the materials could be restricted effectively. The corrosion mechanism of Al2O3-C refractories supposes that (1) K2CO3 was reduced to K vapor and penetrated into the specimen through the open pores and (2) K vapor reacted with SiC, SiO2, and alumina to form KAlSi2O6 and KAlSiO4, which is in agreement with the thermodynamic prediction.

  4. Quantitative characterization of brazing performance for Sn-plated silver alloy fillers

    Science.gov (United States)

    Wang, Xingxing; Peng, Jin; Cui, Datian

    2017-12-01

    Two types of AgCuZnSn fillers were prepared based on BAg50CuZn and BAg34CuZnSn alloy through a combinative process of electroplating and thermal diffusion. The models of wetting entropy and joint strength entropy of AgCuZnSn filler metals were established. The wetting entropy of the Sn-plated silver brazing alloys are lower than the traditional fillers, and its joint strength entropy value is slightly higher than the latter. The wetting entropy value of the Sn-plated brazing alloys and traditional filler metal are similar to the change trend of the wetting area. The trend of the joint strength entropy value with those fillers are consisted with the tensile strength of the stainless steel joints with the increase of Sn content.

  5. Welding/brazing for Space Station repair

    Science.gov (United States)

    Dickinson, David W.; Babel, H. W.; Conaway, H. R.; Hooper, W. H.

    1990-01-01

    Viewgraphs on welding/brazing for space station repair are presented. Topics covered include: fabrication and repair candidates; debris penetration of module panel; welded repair patch; mechanical assembly of utility fluid line; space station utility systems; Soviet aerospace fabrication - an overview; and processes under consideration.

  6. Gold-nickel-titanium brazing alloy

    Science.gov (United States)

    Mizuhara, Howard

    1990-07-03

    A brazing alloy in accordance with this invention has the following composition, by weight: 91 to 99% gold, 0.5 to 7% nickel; 0.10 to 2% titanium. Alternatively, with palladium present, the composition is as follows, by weight: 83 to 96% gold; 3 to 10% palladium; 0.5 to 5% nickel; 0.10 to 2% titanium.

  7. Holding Tubes in Place for Brazing

    Science.gov (United States)

    Ambrisco, D.; Arbino, P.

    1983-01-01

    Simple method prevents loosening due to thermal mismatch. Four segment die pushed outward against tubing wall by tapered ram. Boss on each segment of die produces dimple in wall. Ram driven by commercial pneumatic cylinder powered by air at 250 psi. Method applicable to brazing of heat exchanges, thrust chambers, and other assemblies in which thermal expansion coefficients of materials differ significantly.

  8. Diffusion brazing nickel-plated stainless steel

    Science.gov (United States)

    Beuyukian, C. S.; Mitchell, M. J.

    1976-01-01

    To bond parts, sandwich assembly is made up of aluminum core, aluminum face sheet with brazing alloy interface, and nickel plated stainless steel part. Sandwich is placed between bottom and top glide sheet that is placed in stainless steel retort where assembly is bonded at 580 C.

  9. Development of W-composites/EUROFER brazed joints for the first wall component of future fusion reactors

    Science.gov (United States)

    de Prado, J.; Sánchez, M.; Antusch, S.; Ureña, A.

    2017-12-01

    The present work describes a joining procedure between two different tungsten composite materials (W–2Y2O3 and W–1TiC) with reduced activation ferritic–martensitic steel (Eurofer). The results indicated the achievement, in both cases, of high quality W-composites/Eurofer joints using 80Cu–20Ti as filler material. The braze is constituted by several ternary Cu–Ti–Fe phases distributed along a Cu-matrix, which acts as ductile phase capable of relieving the residual stresses, which could be produced during the service life of the component. Some cracks growing from W–braze interface into the base material have been detected. They are originated by the stresses produced during the cooling stage of the brazing cycle. Regarding the strength of the joints, similar shear strengths of both joints were obtained (∼105 MPa). These values were slightly lower than the ones obtained when pure tungsten was used as the base metal.

  10. Phase analysis of fume during arc weld brazing of steel sheets with protective coatings

    Directory of Open Access Journals (Sweden)

    J. Matusiak

    2016-04-01

    Full Text Available The article presents the results of research of the phase identification and of the quantitative phase analysis of fume generated during Cold Metal Transfer (CMT, ColdArc and Metal Inert Gas / Metal Active Gas (MIG / MAG weld brazing. Investigations were conducted for hot - dip coated steel sheets with zinc (Zn and zinc-iron (Zn - Fe alloy coatings. Arc shielding gases applied during the research-related tests were Ar + O2, Ar + CO2, Ar + H2 and Ar + CO2 + H2 gas mixtures. The analysis of the results covers the influence of the chemical composition of shielding gas on the chemical composition of welding fume.

  11. Highly Refractory Porous Ceramics,

    Science.gov (United States)

    1979-03-14

    also highly refractory porous materials based on co- rundum and magnesite were released in a limited amount.(1,6). The technology of manufacturing...there is an effect of slags and 4and other molten substances ( glasses , metals, etc.), under conditions where there is an effect of gas flows at high...slags, metal, glass , ashes, etc. (Table 53). Table 53 Ta6.,Hua 53 A Upeue~mbuas TenepaTypa npNveneas aA$MocANAEnaTNX n AunacoMux aerolecubM

  12. Chromia refractory brick with carbon treatment

    Science.gov (United States)

    Bennett, James P.; Kwong, Kyei-Sing

    2017-03-21

    The disclosure provides a refractory brick system comprising a chromia refractory brick for operation in the slagging environment of an air-cooled gasifier. The chromia refractory brick comprises a ceramically-bonded porous chromia refractory having a porosity greater than 9% and having carbon deposits residing within the pores. The brick may be further comprised of Al.sub.2O.sub.3. The air-cooled gasifier generates a liquefied slag in contact with the refractory brick and generally operates at temperatures between 1250.degree. C. and 1575.degree. C. and pressures between 300 psi to 1000 psi, with oxygen partial pressures generally between 10.sup.-4 and 10.sup.-10 atm. The refractory brick performs without substantial chromium carbide or chromium metal formation in the low oxygen partial pressure environment. The inclusion of carbon without chromium carbide formation provides for significant mitigation of slag penetration and significantly reduced refractory wear.

  13. 46 CFR 56.75-5 - Filler metal.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Filler metal. 56.75-5 Section 56.75-5 Shipping COAST... Brazing § 56.75-5 Filler metal. (a) The filler metal used in brazing must be a nonferrous metal or alloy having a melting point above 1,000 °F. and below that of the metal being joined. The filler metal must...

  14. PROSES BRAZING Cu-Ag BERBAHAN BAKAR BIOGAS TERMURNIKAN

    Directory of Open Access Journals (Sweden)

    Ali Kusrijadi

    2015-01-01

    Full Text Available Pemanfaatan biogas sebagai salah satu alternatif bahan bakar  pada proses brazing merupakan langkah diversifikasi biogas, yang diharapkan dapat meningkatkan tingkat efisiensi dan keramahan teknologi. Permasalahan yang bersifat teknis dan menjadi kendala dalam pemanfaatan biogas ini adalah rendahnya konsentrasi CH4 dikarenakan adanya pengotor utama berupa air, karbondioksida dan asam disulfida. Penelitian dilakukan melalui dua tahap yaitu  tahap  pressureized storage process meliputi pemisahan komponen pengotor yang terdapat dalam biogas melalui teknik absorbsi sehingga dihasilkan biogas yang berkualitas gas alam terbarukan dan proses injeksi ke dalam suatu tangki penyimpanan, dan tahap selanjutnya adalah menggunakan biogas tersebut pada proses brazing logam Cu (tembaga dengan bahan tambah Ag (silver. Analisis hasil brazing dilakukan melalui analisis struktur mikro (metalografi untuk melihat kualitas tampak dari hasil brazing, serta analisis kekerasan mikro dan analisis parameter fisik standar terhadap hasil proses brazing. Penelitian ini telah menghasilkan perangkat alat pemurnian biogas yang dapat memurnikan biogas menjadi metana mendekati 100% dan sistem pengemasan (storage system  biogas bertekanan hingga 2 bar. Dari hasil analisis struktur mikro dan uji kekerasan mikro diketahui bahwa hasil proses brazing dengan biogas menghasilkan kualitas yang sama dengan hasil proses brazing dengan gas acetylene sehingga disimpulkan bahwa biogas dapat menjadi bahan bakar alternatif untuk proses brazing, khususnya untuk logam Cu dengan bahan tambah Ag.  Kata kunci : Biogas, Pressureized Storage, Brazing

  15. Intermediate layer, microstructure and mechanical properties of aluminum alloy/stainless steel butt joint using laser-MIG hybrid welding-brazing method

    Science.gov (United States)

    Zhu, Zongtao; Wan, Zhandong; Li, Yuanxing; Xue, Junyu; Hui, Chen

    2017-07-01

    Butt joining of AA6061 aluminum (Al) alloy and 304 stainless steel of 2-mm thickness was conducted using laser-MIG hybrid welding-brazing method with ER4043 filler metal. To promote the mechanical properties of the welding-brazing joints, two kinds of intermediate layers (Al-Si-Mg alloy and Ag-based alloy) are used to adjust the microstructures of the joints. The brazing interface and the tensile strength of the joints were characterized. The results showed that the brazing interface between Al alloy and stainless steel consisted of double layers of Fe2Al5 (near stainless steel) and Fe4Al13 intermetallic compounds (IMCs) with a total thickness of 3.7 μm, when using Al-Si-Mg alloy as the intermediate layer. The brazing interface of the joints using Ag-based alloy as intermediate layer also consists of double IMC layers, but the first layer near stainless steel was FeAl2 and the total thickness of these two IMC layers decreased to 3.1 μm. The tensile strength of the joints using Al-Si-Mg alloy as the intermediate layer was promoted to 149 MPa, which was 63 MPa higher than that of the joints using Al-Si-Mg alloy as the intermediate layer. The fractures occurred in the brazing interface between Al alloy and stainless steel.

  16. Crack repair welding by CMT brazing using low melting point filler wire for long-term used steam turbine cases of Cr-Mo-V cast steels

    Energy Technology Data Exchange (ETDEWEB)

    Kadoi, Kota, E-mail: kadoi@hiroshima-u.ac.jp [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Murakami, Aoi; Shinozaki, Kenji; Yamamoto, Motomichi [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Matsumura, Hideo [Chugoku Electric Power Co., 3-9-1 Kagamiyama, Higashi-Hiroshima 739-0046 (Japan)

    2016-06-01

    Surface melting by gas tungsten arc (GTA) welding and overlaying by cold metal transfer (CMT) brazing using low melting point filler wire were investigated to develop a repair process for cracks in worn cast steel of steam turbine cases. Cr-Mo-V cast steel, operated for 188,500 h at 566 °C, was used as the base material. Silver and gold brazing filler wires were used as overlaying materials to decrease the heat input into the base metal and the peak temperature during the welding thermal cycle. Microstructural analysis revealed that the worn cast steel test samples contained ferrite phases with intragranular precipitates of Cr{sub 7}C{sub 3}, Mo{sub 2}C, and CrSi{sub 2} and grain boundary precipitates of Cr{sub 23}C{sub 6} and Mo{sub 2}C. CMT brazing using low melting point filler wire was found to decrease the heat input and peak temperature during the thermal cycle of the process compared with those during GTA surface melting. Thus, the process helped to inhibit the formation of hardened phases such as intermetallics and martensite in the heat affected zone (HAZ). Additionally, in the case of CMT brazing using BAg-8, the change in the hardness of the HAZ was negligible even though other processes such as GTA surface melting cause significant changes. The creep-fatigue properties of weldments produced by CMT brazing with BAg-8 were the highest, and nearly the same as those of the base metal owing to the prevention of hardened phase formation. The number of fracture cycles using GTA surface melting and CMT brazing with BAu-4 was also quite small. Therefore, CMT brazing using low melting point filler wire such as BAg-8 is a promising candidate method for repairing steam turbine cases. However, it is necessary to take alloy segregation during turbine operation into account to design a suitable filler wire for practical use.

  17. Titanium Brazing for Structures and Survivability

    Science.gov (United States)

    2007-05-01

    first method ( Weld +HIP) was a tungsten inert gas ( TIG ) weld around the exterior of the Ti- 6Al-4V blocks followed by hot isostatic pressing (HIP) at...structural material is much less mature than both steel and aluminum alloys, especially in the area of joining. While welding is the typical joining...method for titanium, vacuum brazing is an option in areas that are difficult to access for welding as well as areas near other nonmetallic

  18. Brazing of Carbon Carbon Composites to Cu-clad Molybdenum for Thermal Management Applications

    Science.gov (United States)

    Singh, M.; Asthana, R.; Shpargel, T> P.

    2007-01-01

    Advanced carbon carbon composites were joined to copper-clad molybdenum (Cu/Mo) using four active metal brazes containing Ti (Cu ABA, Cusin-1 ABA, Ticuni, and Ticusil) for potential use in thermal management applications. The brazed joints were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Knoop microhardness measurements across the joint region. Metallurgically sound C-C/Cu/Mo joints, devoid of interfacial cracks formed in all cases. The joint interfaces were preferentially enriched in Ti, with Cu ABA joints exhibiting the largest interfacial Ti concentrations. The microhardness measurements revealed hardness gradients across the joint region, with a peak hardness of 300-350 KHN in Cusin-1 ABA and Ticusil joints and 200-250 KHN in Cu ABA and Ticuni joints, respectively.

  19. Brazing of SiC using Cu-Si non reactive alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gasse, A. [C.E.A., CEREM-DEM, Grenoble (France); Chaumat, G. [C.E.A., CEREM-DEM, Grenoble (France); Rado, C. [INPG/LTCM-ENSEEG, Saint Martin d`Heres (France); Eustathopoulos, N. [INPG/LTCM-ENSEEG, Saint Martin d`Heres (France)

    1995-12-31

    SiC was brazed with a Cu 24 at% Si alloy under high vacuum at 1473 K. This alloy well wets SiC without any measurable reactivity and after cooling, leads to an interface which appears to be strong. It was found that the degree of filling of the joint by the alloy depends mainly on the geometry of the ceramic-metal-vapour system. It is shown that geometrical factors influence the kinetics of deoxidation of both alloys and SiC surfaces and, as a consequence, considerably modify the wetting kinetics and filling of the joint. Successful helium-tight tube/plate brazed joints have been obtained. Nevertheless, thermal expansion mismatch remains considerable between the SiC and the Cu-Si alloy. Further work is needed to improve the mechanical behaviour of such junctions to avoid crack formation. (orig./MM)

  20. HIGHLY REFRACTORY CRUCIBLES OF STABILIZED ZIRCONIA FOR INDUCTION MELTING OF THE PLATINUM GROUP METALS, FABRICATED BY VIBROCASTING

    Directory of Open Access Journals (Sweden)

    V. V. Primachenko

    2012-01-01

    Full Text Available As the result of the studies at PJSC « UKRNIIO them. A.S.Berezhnogo» the technology and commercial production of crucibles from stabilized zirconia for the smelting of platinum group metals are develop

  1. Temporary metallic stent placement in the treatment of refractory benign esophageal strictures: results and factors associated with outcome in 55 patients

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Hyoung; Kim, Kyung Rae; Shin, Ji Hoon; Lim, Jin-Oh [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea); Song, Ho-Young [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea)]|[University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology, Seoul (Korea); Choi, Eugene K. [Weill Medical College of Cornell University, New York, NY (United States)

    2009-02-15

    The purpose of this study was to evaluate the effectiveness of temporary metallic stenting in 55 patients with treatment-resistant benign esophageal strictures and to identify factors associated with clinical outcomes. Under fluoroscopic guidance, covered retrievable stents were placed in 55 patients with benign esophageal strictures and were removed with retrieval hook 1 week to 6 months after placement. Stent placement was successful in all patients, and the mean dysphagia score was reduced from 2.8 to 1.3 (p<0.001). The most common complications were tissue hyperproliferation (31%), severe pain (24%), and stent migration (25%). During follow-up (mean: 38 months), recurrence of the stricture necessitating balloon dilation was seen in 38 (69%) of 55 patients. Maintained patency rates after temporary stenting at 1, 3, and 6 months and 1, 2, and 4 years were 58%, 43%, 38%, 33%, 26%, and 21%, respectively. In multivariate analysis, length (p=0.003) of the stricture was the only significant factor associated with maintained patency after temporary stenting. In conclusion, temporary metallic stenting for refractory benign esophageal strictures may be effective during the period of stent placement, but is disadvantaged by the high recurrence rates after stent removal, particularly in patients with a long length of stricture (>7cm). (orig.)

  2. 46 CFR 56.75-20 - Brazing qualification.

    Science.gov (United States)

    2010-10-01

    ... brazing operators shall be in accordance with the requirements of part C, Section IX of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see 46 CFR 56.01-2) and part 57 of this... 46 Shipping 2 2010-10-01 2010-10-01 false Brazing qualification. 56.75-20 Section 56.75-20...

  3. Microwave-assisted brazing of alumina ceramics for electron tube ...

    Indian Academy of Sciences (India)

    The brazed joints were characterizedby X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, Vickers microhardness evaluation, brazing strength measurement and helium leak test. X-ray diffraction analysis confirmed the formationof Ti-based compounds at the substrate-filler alloy interfaces of ...

  4. Liquid Film Migration in Warm Formed Aluminum Brazing Sheet

    Science.gov (United States)

    Benoit, M. J.; Whitney, M. A.; Wells, M. A.; Jin, H.; Winkler, S.

    2017-10-01

    Warm forming has previously proven to be a promising manufacturing route to improve formability of Al brazing sheets used in automotive heat exchanger production; however, the impact of warm forming on subsequent brazing has not previously been studied. In particular, the interaction between liquid clad and solid core alloys during brazing through the process of liquid film migration (LFM) requires further understanding. Al brazing sheet comprised of an AA3003 core and AA4045 clad alloy, supplied in O and H24 tempers, was stretched between 0 and 12 pct strain, at room temperature and 523K (250 °C), to simulate warm forming. Brazeability was predicted through thermal and microstructure analysis. The rate of solid-liquid interactions was quantified using thermal analysis, while microstructure analysis was used to investigate the opposing processes of LFM and core alloy recrystallization during brazing. In general, liquid clad was consumed relatively rapidly and LFM occurred in forming conditions where the core alloy did not recrystallize during brazing. The results showed that warm forming could potentially impair brazeability of O temper sheet by extending the regime over which LFM occurs during brazing. No change in microstructure or thermal data was found for H24 sheet when the forming temperature was increased, and thus warm forming was not predicted to adversely affect the brazing performance of H24 sheet.

  5. Disk Laser Weld Brazing of AW5083 Aluminum Alloy with Titanium Grade 2

    Science.gov (United States)

    Sahul, Miroslav; Sahul, Martin; Vyskoč, Maroš; Čaplovič, Ľubomír; Pašák, Matej

    2017-03-01

    Disk laser weld brazing of dissimilar metals was carried out. Aluminum alloy 5083 and commercially pure titanium Grade 2 with the thickness of 2.0 mm were used as experimental materials. Butt weld brazed joints were produced under different welding parameters. The 5087 aluminum alloy filler wire with a diameter of 1.2 mm was used for joining dissimilar metals. The elimination of weld metal cracking was attained by offsetting the laser beam. When the offset was 0 mm, the intermixing of both metals was too high, thus producing higher amount of intermetallic compounds (IMCs). Higher amount of IMCs resulted in poorer mechanical properties of produced joints. Grain refinement in the fusion zone occurred especially due to the high cooling rates during laser beam joining. Reactions at the interface varied in the dependence of its location. Continuous thin IMC layer was observed directly at the titanium-weld metal interface. Microhardness of an IMC island in the weld metal reached up to 452.2 HV0.1. The XRD analysis confirmed the presence of tetragonal Al3Ti intermetallic compound. The highest tensile strength was recorded in the case when the laser beam offset of 300 μm from the joint centerline toward aluminum alloy was utilized.

  6. In Situ Synthesis of Al-Si-Cu Alloy During Brazing Process and Mechanical Property of Brazing Joint

    OpenAIRE

    LONG Wei-min; LU Quan-bin; He, Peng; XUE Song-bai; Wu, Ming-Fang; Xue, Peng

    2016-01-01

    The Al-Si-Cu alloy system is considered to be a promising choice of filler metal for aluminium alloys brazing due to its high strength and low melting point. The greatest obstacle is its lack of plastic forming ability and being difficult to be processed by conventional methods. This disadvantage is ascribed to the considerable amount of brittle CuAl2 intermetallic compound which forms when alloy composition is around the ternary eutectic point. In order to overcome this deficiency, authors o...

  7. Effect of holding time on microstructure and mechanical properties of SiC/SiC joints brazed by Ag-Cu-Ti + B4C composite filler

    OpenAIRE

    Dai, Xiangyu; Cao, Jian; Tian, Yingtao; Chen, Zhe; Song, Xiaoguo; Feng, Jicai

    2016-01-01

    The composite fillers have a number of advantages comparing with the traditional filler metals, and have been widely used for brazing ceramics. However, previous researches mainly focus on the strengthening mechanism of either whiskers or particles. It is still of great interest to investigate the reinforcement effect with the presence of both whiskers and particles. In this study, Ag-Cu-Ti + B4C composite filler was developed to braze SiC ceramics, and effects of holding time on the microstr...

  8. Composition and method for brazing graphite to graphite

    Science.gov (United States)

    Taylor, A.J.; Dykes, N.L.

    1982-08-10

    A brazing material is described for joining graphite structures that can be used up to 2800/sup 0/C. The brazing material is formed of a paste-like composition of hafnium carbide and uranium oxide with a thermosetting resin. The uranium oxide is converted to uranium dicarbide during the brazing operation and then the hafnium carbide and uranium dicarbide form a liquid phase at a temperature about 2600/sup 0/C with the uranium diffusing and vaporizing from the joint area as the temperature is increased to about 2800/sup 0/C so as to provide a brazed joint consisting essentially of hafnium carbide. The resulting brazed joint is chemically and thermally compatible with the graphite structures.

  9. Active metal brazing of various metals on nitride ceramics

    OpenAIRE

    Pönicke, A.; Rost, A.; Schilm, J.; Michaelis, A.

    2013-01-01

    The development of new materials for thermoelectric generators (TEG) with higher operating temperatures requires improved metallised substrates. Commonly used alumina substrates with copper metallisation show low thermal conductivity and low stability against thermal cycles. Aluminum nitride (AlN) and silicon nitride (Si3N4) are very attractive alternative substrate materials due to their high thermal conductivity, electrical resistivity and mechanical strength. However, it is important to re...

  10. A Combined Brazing and Aluminizing Process for Repairing Turbine Blades by Thermal Spraying Using the Coating System NiCrSi/NiCoCrAlY/Al

    Science.gov (United States)

    Nicolaus, M.; Möhwald, K.; Maier, H. J.

    2017-10-01

    The repair and maintenance of components in the aerospace industry play an increasingly important role due to rising manufacturing costs. Besides welding, vacuum brazing is a well-established repair process for turbine blades made of nickel-based alloys. After the coating of the worn turbine blade has been removed, the manual application of the nickel-based filler metal follows. Subsequently, the hot gas corrosion-protective coating is applied by thermal spraying. The brazed turbine blade is aluminized to increase the hot gas corrosion resistance. The thermal spray technology is used to develop a two-stage hybrid technology that allows shortening the process chain for repair brazing turbine blades and is described in the present paper. In the first step, the coating is applied on the base material. Specifically, the coating system employed here is a layer system consisting of nickel filler metal, NiCoCrAlY and aluminum. The second step represents the combination of brazing and aluminizing of the coating system which is subjected to a heat treatment. The microstructure, which results from the combined brazing and aluminizing process, is characterized and the relevant diffusion processes in the coating system are illustrated. The properties of the coating and the ramifications with respect to actual applications will be discussed.

  11. Effects of Thermal Cycling and Thermal Aging on the Hermeticity and Strength of Silver-Copper Oxide Air-Brazed Seals

    Energy Technology Data Exchange (ETDEWEB)

    Weil, K. Scott; Coyle, Christopher A.; Darsell, Jens T.; Xia, Gordon; Hardy, John S.

    2005-12-01

    Thermal cycle and exposure tests were conducted on ceramic-to-metal joints prepared by a new sealing technique. Known as reactive air brazing, this joining method is currently being considered for use in sealing various high-temperature solid-state electrochemical devices, including planar solid oxide fuel cells (pSOFC). In order to simulate a typical pSOFC application, test specimens were prepared by joining ceramic anode/electrolyte bilayers to washers, of the same composition as the common frame materials employed in pSOFC stacks, using a filler metal composed of 4mol% CuO in silver. The brazed samples were exposure tested at 750°C for 200, 400, and 800hrs in both simulated fuel and air environments and thermally cycled at rapid rate (75°C/min) between room temperature and 750°C for as many as fifty cycles. Subsequent joint strength testing and microstructural analysis indicated that the samples exposure tested in air displayed little degradation with respect to strength, hermeticity, or microstructure out to 800hrs of exposure. Those tested in fuel showed no change in rupture strength or loss in hermeticity after 800hrs of high-temperature exposure, but did undergo microstructural change due to the dissolution of hydrogen into the silver-based braze material. Air brazed specimens subjected to rapid thermal cycling exhibited no loss in joint strength or hermeticity, but displayed initial signs of seal delamination along the braze/electrolyte interface after 50 cycles.

  12. Multiple-unit implant frames: one-piece casting vs. laser welding and brazing.

    Science.gov (United States)

    Costa, Elza Maria Valadares da; Neisser, Maximiliano Piero; Bottino, Marco Antônio

    2004-09-01

    The linear distortion of prostheses over implants, one-piece casting and cast in sections followed by laser welding by laser and brazing was evaluated in an edentulous mandibular model with five parallel abutments, with a distance of 10mm from center to center. Seventy five gold cylinders were tightened with screws on the abutments with 10Ncm torque. The cylinder/analogue assemblies were measured by microscopic examination (0.001mm accuracy) and the obtained results were compared with the GC (control group). Fifteen metal frames were waxed and cast in a gold alloy (Stabilor, Degussa Hulls, Brazil) and divided into three groups with five elements each, as followed: GM (one-piece casting), GB (section and brazing) and GL (section and laser welding). In all groups, measurements were taken at the right, left, buccal and lingual sides of the cylinder/analogue interface and the results were submitted to analysis of variance (ANOVA) and to the Tukey test (5%). The smallest amount of distortion was seen in the laser group (GL with a mean value of 13.58), followed by the brazing group (GB with a mean value of 24.33) and one-piece (GM with a mean value of 40.00). The greatest distortion was found in the one-piece group (GM).

  13. Environmental and energy gains from using molten magnesium–sodium–potassium chlorides for electro-metallisation of refractory metal oxides

    Directory of Open Access Journals (Sweden)

    Wei Li

    2015-12-01

    Full Text Available The molten eutectic mixture of magnesium, sodium and potassium chlorides (MgCl2–NaCl–KCl has inappreciable solubility for oxide ions, and can help disengage a carbon anode from the oxide ions generated at a metal oxide cathode, and effectively avoid carbon dioxide formation. This “disengaging strategy” was successfully demonstrated in electro-reduction of solid oxides of zirconium and tantalum. It has led to significantly higher current efficiency (93%, and lower energy consumption (1.4 kW h kg−1 in electrolysis of tantalum oxide to tantalum metal compared to the conventional electrolysis in molten calcium chloride (e.g. 78% and 2.4 kW h/kg-Ta.

  14. Control of Vacuum Induction Brazing System for Sealing of Instrumentation Feedthrough

    Science.gov (United States)

    Ahn, Sung Ho; Hong, Jintae; Joung, Chang Young; Heo, Sung Ho

    2017-04-01

    The integrity of instrumentation cables is an important performance parameter in the brazing process, along with the sealing performance. In this paper, an accurate control scheme for brazing of the instrumentation feedthrough in a vacuum induction brazing system was developed. The experimental results show that the accurate brazing temperature control performance is achieved by the developed control scheme. It is demonstrated that the sealing performances of the instrumentation feedthrough and the integrity of the instrumentation cables are to be acceptable after brazing.

  15. Furnace Brazing Parameters Optimized by Taguchi Method and Corrosion Behavior of Tube-Fin System of Automotive Condensers

    Science.gov (United States)

    Guía-Tello, J. C.; Pech-Canul, M. A.; Trujillo-Vázquez, E.; Pech-Canul, M. I.

    2017-08-01

    Controlled atmosphere brazing has a widespread industrial use in the production of aluminum automotive heat exchangers. Good-quality joints between the components depend on the initial condition of materials as well as on the brazing process parameters. In this work, the Taguchi method was used to optimize the brazing parameters with respect to corrosion performance for tube-fin mini-assemblies of an automotive condenser. The experimental design consisted of five factors (micro-channel tube type, flux type, peak temperature, heating rate and dwell time), with two levels each. The corrosion behavior in acidified seawater solution pH 2.8 was evaluated through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. Scanning electron microscope (SEM) and energy-dispersive x-ray spectroscopy (EDS) were used to analyze the microstructural features in the joint zone. The results showed that the parameters that most significantly affect the corrosion rate are the type of flux and the peak temperature. The optimal conditions were: micro-channel tube with 4.2 g/m2 of zinc coating, standard flux, 610 °C peak temperature, 5 °C/min heating rate and 4 min dwell time. The corrosion current density value of the confirmation experiment is in excellent agreement with the predicted value. The electrochemical characterization for selected samples gave indication that the brazing conditions had a more significant effect on the kinetics of the hydrogen evolution reaction than on the kinetics of the metal dissolution reaction.

  16. COMPARATION BETWEEN NONDESTRUCTIVE TESTING METHODS FOR THE ALUMINIUM BRAZED PIECES

    Directory of Open Access Journals (Sweden)

    Dan NIŢOI

    2014-05-01

    Full Text Available Presented paper refers to different control methods used in aluminium brazed joining because of possible defects. Low joining complexity permits exact damages position in relation with materials geometry.

  17. Quality assurance of brazed copper plates through advanced ultrasonic NDE

    OpenAIRE

    Segreto, T.; Caggiano, A.; Teti, R.

    2016-01-01

    Ultrasonic non-destructive methods have demonstrated great potential for the detection of flaws in a material under examination. In particular, discontinuities produced by welding, brazing, and soldering are regularly inspected through ultrasonic techniques. In this paper, an advanced ultrasonic non-destructive evaluation technique is applied for the quality control of brazed copper cells in order to realize an accelerometer prototype for cancer proton therapy. The cells are composed of two h...

  18. Interfacial reaction of intermetallic compounds of ultrasonic-assisted brazed joints between dissimilar alloys of Ti6Al4V and Al4Cu1Mg.

    Science.gov (United States)

    Ma, Zhipeng; Zhao, Weiwei; Yan, Jiuchun; Li, Dacheng

    2011-09-01

    Ultrasonic-assisted brazing of Al4Cu1Mg and Ti6Al4V using Zn-based filler metal (without and with Si) has been investigated. Before brazing, the Ti6Al4V samples were pre-treated by hot-dip aluminizing and ultrasonic dipping in a molten filler metal bath in order to control the formation of intermetallic compounds between the Ti6Al4V samples and the filler metal. The results show that the TiAl(3) phase was formed in the interface between the Ti6Al4V substrate and the aluminized coating. For the Zn-based filler metal without Si, the Ti6Al4V interfacial area of the brazed joint did not change under the effect of the ultrasonic wave, and only consisted of the TiAl(3) phase. For the Zn-based filler metal with Si, the TiAl(3) phase disappeared and a Ti(7)Al(5)Si(12) phase was formed at the interfacial area of the brazed joints under the effect of the ultrasonic wave. Due to the TiAl(3) phase completely changing to a Ti(7)Al(5)Si(12) phase, the morphology of the intermetallic compounds changed from a block-like shape into a lamellar-like structure. The highest shear strength of 138MPa was obtained from the brazed joint free of the block-like TiAl(3) phase. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Microstructural and Mechanical Characterization of Actively Brazed Alumina Specimens

    Energy Technology Data Exchange (ETDEWEB)

    Hosking, F.M.; Cadden, C.H.; Stephens, J.J.; Glass, S.J.; Yang, N.Y.C.; Vianco, P.V.; Walker, C.A.

    1999-08-26

    Alumina (94 and 99.8% grade compositions) was brazed directly to itself with gold-based active brazing alloys (ABA's) containing vanadium additions of 1,2 and 3 weight percent. The effects of brazing conditions on the joint properties were investigated. Wetting behavior, interfacial reactions, microstructure, hermeticity and tensile strength were determined. Wetting was fair to good for the ABA and base material combinations. Microanalysis identified a discontinuous Al-V-O spinel reaction product at the alumina-braze interface. Tensile strength results for 94% alumina were uniformly good and generally not sensitive to the vanadium concentration, with tensile values of 85-105 MPa. There was more variability in the 99.8% alumina strength results, with values ranging from 25-95 MPa. The highest vanadium concentration (3 wt. %) yielded the highest joint strength for the brazed 99.8% alumina. Failures in the 99.8% alumina samples occurred at the braze-alumina interface, while the 94% alumina specimens exhibited fracture of the ceramic substrate.

  20. Method For Brazing And Thermal Processing

    Science.gov (United States)

    Milewski, John O.; Dave, Vivek R.; Christensen, Dane; Carpenter, II, Robert W.

    2005-07-12

    The present invention includes a method for brazing of two objects or heat treatment of one object. First, object or objects to be treated are selected and initial conditions establishing a relative geometry and material characteristics are determined. Then, a first design of an optical system for directing heat energy onto the object or objects is determined. The initial conditions and first design of the optical system are then input into a optical ray-tracing computer program. The program is then run to produce a representative output of the heat energy input distribution to the object or objects. The geometry of the object or objects, material characteristics, and optical system design are then adjusted until an desired heat input is determined.

  1. Brazing open cell reticulated copper foam to stainless steel tubing with vacuum furnace brazed gold/indium alloy plating

    Science.gov (United States)

    Howard, Stanley R [Windsor, SC; Korinko, Paul S [Aiken, SC

    2008-05-27

    A method of fabricating a heat exchanger includes brush electroplating plated layers for a brazing alloy onto a stainless steel tube in thin layers, over a nickel strike having a 1.3 .mu.m thickness. The resultant Au-18 In composition may be applied as a first layer of indium, 1.47 .mu.m thick, and a second layer of gold, 2.54 .mu.m thick. The order of plating helps control brazing erosion. Excessive amounts of brazing material are avoided by controlling the electroplating process. The reticulated copper foam rings are interference fit to the stainless steel tube, and in contact with the plated layers. The copper foam rings, the plated layers for brazing alloy, and the stainless steel tube are heated and cooled in a vacuum furnace at controlled rates, forming a bond of the copper foam rings to the stainless steel tube that improves heat transfer between the tube and the copper foam.

  2. Influences of Nozzle Material on Laser Droplet Brazing Joints with Cu89Sn11 Preforms

    Science.gov (United States)

    Stein, Stefan; Heberle, Johannes; Gürtler, Franz Josef; Cvecek, Kristian; Roth, Stephan; Schmidt, Michael

    This paper presents latest results on the influences of nozzle material and geometry on the electromechanical contacting of sensitive piezoceramic actuator modules. Two nozzle types have been investigated,a standard WC/Co nozzle which is used for soldering applications and a novelceramic nozzle. Applications for active piezoceramic components integrated in structural parts are e.g. active damping, energy harvesting, or monitoring of vibrations and material failure. Anup to now unsolved problem is the electrical contacting of such components without damaging the conductor or the metallization of the ceramic substrate. Since piezoelectric components are to be integrated into structures made of casted aluminum, requirements are high mechanical strength and temperature resistance. Within this paper a method forcontacting piezoceramic modules is presented. A spherical braze preform of tin bronze Cu89Sn11 with a diameter of 600 μm is located in a ceramic nozzle and is subsequently melted by a laser pulse. The liquid solder is ejected from the nozzlevia nitrogen overpressure and wets the surface of the metallization pad and the Cu-wire, resulting in a brazing joint after solidification. The process is called laser droplet brazing (LDB). To asses the thermal evolution during one cycle WC/Co and ZTA have been simulated numerically for two different geometries enabling a proposition weather the geometry or the material properties have a significant influence on the thermal load during one cycle. To evaluate the influence of the nozzle on the joint the positioning accuracy, joint height and detachment times have been evaluated. Results obtained with the ZTA nozzle show comparable positioning accuracies to a WC/Co nozzle with a lower standard deviation of solder detachment time.

  3. Braze Alloy Development for Fast Epitaxial High-Temperature Brazing of Single-Crystalline Nickel-Based Superalloys

    Science.gov (United States)

    Laux, B.; Piegert, S.; Rösler, J.

    2009-01-01

    For the repair of single-crystalline turbine components, fabricated from nickel-based superalloys, a new high-temperature brazing technology has been developed. Cracks in single-crystalline parts can be repaired by reproducing the single-crystalline microstructure over the complete gap width within very short brazing times. Nickel-manganese-based alloys were identified as systems that provide very high, epitaxial solidification rates. In contrast to commonly used braze alloys, such as nickel-boron or nickel-silicon systems, the process is not completely diffusion controlled but works with consolute systems. For brazing experiments 300- μm-wide parallel gaps as well as V-shaped gaps with a maximum width of 250 μm were used. A complete epitaxial solidification, that is, the absence of large-angle grain boundaries, could be achieved within brazing times, being up to 100 times shorter compared to commonly used transient-liquid-phase bonding technologies. To quantify the misorientation relative to the base material and the composition within and near the filled gaps, the results of the brazing experiments were visualized by means of light microscopy and scanning electron microscopy (SEM). Furthermore, electron backscatter diffraction (EBSD) analyses and energy dispersive X-ray (EDX) analyses were conducted.

  4. Present situation of refractories in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Bittencourt, P. (Magnesita S.A., (Brazil))

    1992-11-10

    This paper outlines the present situation of refractories in Brazil, particularly the use of refractories in the steel industry which is one of the major industries in this country. Brazil is the 8th largest steel producer in the world, and about 64% of all the production is exported. Because of increasing competitions in the world market, high-level production techniques are required, and active improvements of refractories are also being carried out. The specific consumption of refractories in 1 ton of steel has gradually decreased to produce high-quality refractories. In Brazil, 95% of all demand except for special items such as submerged nozzles and blast furnace carbon blocks can be provided domestically. It is characteristic that raw materials for refractories, such as magnesite, bauxite, and graphite can also be self-supporting. Compositions and physical properties of typical refractories used for various purposes in iron and steel manufactures including blast furnaces, torpedo cars, BOF converters, electric are furnaces, and electric arc ladles are described, and the direction toward their conversion into new materials is shown. Moreover, the trends of refractories for the cement industry and for nonferrous metals such as aluminum are introduced. 6 figs., 15 tabs.

  5. REFRACTORY DIE FOR EXTRUDING URANIUM

    Science.gov (United States)

    Creutz, E.C.

    1959-08-11

    A die is presented for the extrusion of metals, said die being formed of a refractory complex oxide having the composition M/sub n/O/sub m/R/sub x/O/sub y/ where M is magnesium, zinc, manganese, or iron, R is aluminum, chromic chromium, ferric iron, or manganic manganese, and m, n, x, and y are whole numbers. Specific examples are spinel, magnesium aluminate, magnetite, magnesioferrite, chromite, and franklinite.

  6. In-process oxidation protection in fluxless brazing or diffusion bonding of aluminum alloys

    Science.gov (United States)

    Okelly, K. P.; Featherston, A. B.

    1974-01-01

    Aluminum is cleaned of its oxide coating and is sealed immediately with polymeric material which makes it suitable for fluxless brazing or diffusion bonding. Time involved between cleaning and brazing is no longer critical factor.

  7. THE INFLUENCE OF HIGH-TEMPERATURE BRAZING UPON INDICATORS OF MATERIAL BRAZEABILITY

    Directory of Open Access Journals (Sweden)

    Roman Koleňák

    2010-03-01

    Full Text Available The effect of both common and extreme parameters of AISI 321stainless steel high-temperature brazing using the NI 102 brazing alloy upon material brazeability indicators. The ascertainment of the wetting angle, the area over which Ni brazing alloy spreads, the width of AISI 321 steel's dissolubility band, and the width of Ni brazing alloy’s diffusion band into the basic material.

  8. Laser Droplet Brazing for the Electrical Contacting of Composite Materials with Integrated Active Elements

    Science.gov (United States)

    Held, Carolin; Quentin, Ulf; Heberle, Johannes; Gürtler, Franz-Josef; Weigl, Markus; Schmidt, Michael

    This paper describes a laser droplet brazing method for electrical contacting of sensitive piezoceramic actuator modules. In order to increase the reproducibility of the contacting process, the mass, the energy and the flight path of the braze droplets have to be controlled. For this reason, braze preforms are used which are molten by a single laser pulse. The system technology and first results will be presented, as well as a mechanical and metallurgical analysis of the brazed connections.

  9. Carbon Based Refractories

    National Research Council Canada - National Science Library

    EWAIS, Emad Mohamed M

    2004-01-01

    .... They are classified into two groups; carbon/bricks/blocks and carbon containing materials. Carbon containing materials are further classified into carbon containing basic refractories and non-basic refractories...

  10. Microstructural Changes in Brazing Sheet due to Solid-Liquid Interaction

    NARCIS (Netherlands)

    Wittebrood, A.J.

    2009-01-01

    Aluminium brazing sheet is the material of choice to produce automotive heat exchangers. Although in Dutch the official translation of aluminium brazing sheet is “aluminium hardsoldeerplaat” the English name is used in the industry. Aluminium brazing sheet is basically a sandwich material and

  11. Effects of thermal cycling and thermal aging on the hermeticity and strength of silver-copper oxide air-brazed seals

    Energy Technology Data Exchange (ETDEWEB)

    Scott Weil, K.; Coyle, Christopher A.; Hardy, John S. [Energy Science and Technology Division, Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Darsell, Jens T. [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States); Xia, Gordon G. [Environmental Technology Division, Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

    2005-12-01

    Thermal cycle and exposure tests were conducted on ceramic-to-metal joints prepared by a new sealing technique. Known as reactive air brazing, this joining method is currently being considered for use in sealing various high-temperature solid-state electrochemical devices, including planar solid oxide fuel cells (pSOFC). In order to simulate a typical pSOFC application, test specimens were prepared by joining ceramic anode/electrolyte bilayers to metal washers, of the same composition as the common frame materials employed in pSOFC stacks, using a filler metal composed of 4mol% CuO in silver. The brazed samples were exposure tested at 750{sup o}C for 200, 400, and 800h in both simulated fuel and air environments and thermally cycled at rapid rate (75{sup o}Cmin{sup -1}) between room temperature and 750{sup o}C for as many as 50 cycles. Subsequent joint strength testing and microstructural analysis indicated that the samples exposure tested in air displayed little degradation with respect to strength, hermeticity, or microstructure out to 800h of exposure. Those tested in fuel showed no change in rupture strength or loss in hermeticity after 800h of high-temperature exposure, but did undergo microstructural change due to the dissolution of hydrogen into the silver-based braze material. Air-brazed specimens subjected to rapid thermal cycling exhibited no loss in joint strength or hermeticity, but displayed initial signs of seal delamination along the braze-electrolyte interface after 50 cycles. (author)

  12. Direct use geothermal applications for brazed plate heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rafferty, K.

    1993-02-01

    Brazed plate heat exchanger were placed in three geothermal fluids (Klamath Falls, OR; Boise, ID; and Pagosa Springs, CO) in order to determine the effect of H[sub 2]S on braze material. Based on subsequent analysis, it appears that the rate of corrosion of the braze material is much slower than corrosion of copper tube materials in the same fluids. Minimum expected life of the heat exchangers based on these corrosion rates is reported to be 12 years in fluids of less than 1 ppm H[sub 2]S and 10 years in fluids of less than 5 ppm. Based on these expected lives, and using a 3% inflation rate and 8% discount rate, brazed plate heat exchangers are a clear economic choice in which the capital cost is 50% or less of the cost of a plate and frame heat exchanger for the same duty. Due to their single pass design, brazed plate heat exchangers are generally limited to approach temperatures of 10[degree] or greater. Size limitations restrict applications to 100 gpm and/or 200 ft[sup 2] heat transfer surface area.

  13. Direct use geothermal applications for brazed plate heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rafferty, K.

    1992-01-01

    Brazed plate heat exchanger were placed in three geothermal fluids (Klamath Falls, OR; Boise, ID; and Pagosa Springs, CO) to determine the effect of H[sub 2]S on braze material. Based on subsequent analysis, it appears that the rate of corrosion of the braze material is much slower than corrosion of copper tube materials in the same fluids. Minimum expected life of the heat exchangers based on these corrosion rates is reported to be 12 years in fluids of less than 1 ppm H[sub 2]S and 10 years in fluids of less than 5 ppm. Based on these expected lives, and using a 3% inflation rate and 8% discount rate, brazed plate heat exchangers are a clear economic choice in which the capital cost is 50% or less of the cost of a plate and frame heat exchanger for the same duty. Due to their single pass design, brazed plate heat exchangers are generally limited to approach temperatures of 10[degrees] or greater. Size limitations restrict applications to 100 gpm and/or 200 ft[sup 2] heat transfer surface area.

  14. Direct use geothermal applications for brazed plate heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rafferty, K.

    1993-02-01

    Brazed plate heat exchanger were placed in three geothermal fluids (Klamath Falls, OR; Boise, ID; and Pagosa Springs, CO) in order to determine the effect of H{sub 2}S on braze material. Based on subsequent analysis, it appears that the rate of corrosion of the braze material is much slower than corrosion of copper tube materials in the same fluids. Minimum expected life of the heat exchangers based on these corrosion rates is reported to be 12 years in fluids of less than 1 ppm H{sub 2}S and 10 years in fluids of less than 5 ppm. Based on these expected lives, and using a 3% inflation rate and 8% discount rate, brazed plate heat exchangers are a clear economic choice in which the capital cost is 50% or less of the cost of a plate and frame heat exchanger for the same duty. Due to their single pass design, brazed plate heat exchangers are generally limited to approach temperatures of 10{degree} or greater. Size limitations restrict applications to 100 gpm and/or 200 ft{sup 2} heat transfer surface area.

  15. Direct use geothermal applications for brazed plate heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rafferty, K.

    1992-12-31

    Brazed plate heat exchanger were placed in three geothermal fluids (Klamath Falls, OR; Boise, ID; and Pagosa Springs, CO) to determine the effect of H{sub 2}S on braze material. Based on subsequent analysis, it appears that the rate of corrosion of the braze material is much slower than corrosion of copper tube materials in the same fluids. Minimum expected life of the heat exchangers based on these corrosion rates is reported to be 12 years in fluids of less than 1 ppm H{sub 2}S and 10 years in fluids of less than 5 ppm. Based on these expected lives, and using a 3% inflation rate and 8% discount rate, brazed plate heat exchangers are a clear economic choice in which the capital cost is 50% or less of the cost of a plate and frame heat exchanger for the same duty. Due to their single pass design, brazed plate heat exchangers are generally limited to approach temperatures of 10{degrees} or greater. Size limitations restrict applications to 100 gpm and/or 200 ft{sup 2} heat transfer surface area.

  16. Microstructures of beta-titanium orthodontic wires joined by infrared brazing.

    Science.gov (United States)

    Iijima, Masahiro; Brantley, William A; Kawashima, Isao; Baba, Naoki; Alapati, Satish B; Yuasa, Toshihiro; Ohno, Hiroki; Mizoguchi, Itaru

    2006-10-01

    The microstructures and interdiffusion in brazed beta-titanium orthodontic wires were investigated by scanning electron microscopy and electron probe microanalysis, respectively. Beta-titanium wire (Ti-11Mo-6Zr-4Sn) with cross-section dimensions of 0.032 in. x 0.032 in., titanium-based braze alloy (Ti-30Ni-20Cu), and silver-based braze alloy (Ag-22Cu-17Zn-5Sn) were selected for the study. Brazing was performed using infrared radiation (RS-1) under an argon atmosphere. Specimens were etched with two solutions (2.5% HF + 2.5% HNO(3) + 95% H(2)O; 25% HN(4)OH + 30% H(2)O(2) + 45%H(2)O). It was found that the silver-based braze alloy has a eutectic structure. In the diffusion layer between the beta-titanium wire and this silver-based braze alloy, Cu and Ti were enriched on the wire side, and Sn and Ti were enriched on the braze alloy side. The titanium-based braze alloy has a dendritic structure. Beta-titanium wire specimens brazed with the titanium-based braze alloy had a thicker intermediate area compared to the silver alloy; Ti in the diffusion layer had an irregular concentration gradient, and the braze alloy side had higher Ti concentration. The original microstructure of the beta-titanium wire was not altered with the use of either braze alloy. Infrared brazing of beta-titanium orthodontic wire is acceptable for clinical use, since the wire microstructure did not deteriorate with either the titanium-based or silver-based braze alloy. The differing microstructures of the joint regions for the two braze alloys suggest that the joint strengths may also differ.

  17. The Effect of Palladium Additions on the Solidus/Liquidus Temperatures and Wetting Properties of Ag-CuO Based Air Brazes

    Energy Technology Data Exchange (ETDEWEB)

    Darsell, Jens T.; Weil, K. Scott

    2007-05-16

    As a means of increasing the use temperature of ceramic-ceramic and ceramic-metal air brazes, palladium was investigated as possible ternary addition to the currently employed silver - copper oxide system. The silver component was directly substituted with palladium to form the following series of alloys: (100-y)[(100-z)Pd - (z)Ag] - (y)CuOx where y = 0 - 34 mol% CuOx, z = 50 - 100 mol% silver, and x = 0, 0.5, and 1, denoting copper metal, Cu2O, or CuO. From differential scanning calorimetry, it was determined that the addition of palladium causes an increase in the solidus and liquidus temperatures of the resulting Pd-Ag-CuO brazes. In general, the liquidus was found to increase by approximately 220°C for the (100-y)(25Pd - 75Ag) - (z)CuOx filler metal compositions relative to comparable Ag-CuOx alloys. Likewise, the solidus was found to increase for these alloys, respectively by 185°C and 60°C, respectively for CuOx contents of y = 0 - 1mol% and 4 - 10 mol%. For the (100-y)(50Pd - 50Ag) - (y)CuOx alloys, the solidus increased between 280 - 390°C over a copper oxide compositional range of x = 0 to 8 mol%. It was determined from sessile drop experiments conducted on alumina substrates that in all cases the palladium causes an increase in the wetting angle relative to the corresponding binary braze. Alloy compositions of (100-y)(25Pd - 75Ag) - (y)CuOx displayed increased wetting angles of 5-20° relative to comparable binary compositions. (100-y)(50Pd - 50Ag) - (y)CuOx alloys exhibited an increase in contact angle of 10-60° and compositions containing less than 10 mol% CuOx were not able to wet the substrate. Scanning electron microscopy indicated that the microstructure of the braze consists of discrete CuOx precipitates in an alloyed silver-palladium matrix. In both the binary and ternary filler metal formulations, a reaction layer consisting of CuAlO2 was observed along the interface with the alumina substrate. This reaction product appears to be beneficial

  18. Multiphysics Simulation and Experimental Investigation of Aluminum Wettability on a Titanium Substrate for Laser Welding-Brazing Process

    Directory of Open Access Journals (Sweden)

    Morgan Dal

    2017-06-01

    Full Text Available The control of metal wettability is a key-factor in the field of brazing or welding-brazing. The present paper deals with the numerical simulation of the whole phenomena occurring during the assembly of dissimilar alloys. The study is realized in the frame of potential applications for the aircraft industry, considering the case of the welding-brazing of aluminum Al5754 and quasi-pure titanium Ti40. The assembly configuration, presented here, is a simplification of the real experiment. We have reduced the three-dimensional overlap configuration to a bi-dimensional case. In the present case, an aluminum cylinder is fused onto a titanium substrate. The main physical phenomena which are considered here are: the heat transfers, the fluid flows with free boundaries and the mass transfer in terms of chemical species diffusion. The numerical problem is implemented with the commercial software Comsol Multiphysics™, by coupling heat equation, Navier-Stokes and continuity equations and the free boundary motion. The latter is treated with the Arbitrary Lagrangian Eulerian method, with a particular focus on the contact angle implementation. The comparison between numerical and experimental results shows a very satisfactory agreement in terms of droplet shape, thermal field and intermetallic layer thickness. The model validates our numerical approach.

  19. Influence of different brazing and welding methods on tensile strength and microhardness of orthodontic stainless steel wire.

    Science.gov (United States)

    Bock, Jens Johannes; Fraenzel, Wolfgang; Bailly, Jacqueline; Gernhardt, Christian Ralf; Fuhrmann, Robert Andreas Werner

    2008-08-01

    The aim of this study was to compare the mechanical strength and microhardness of joints made by conventional brazing and tungsten inert gas (TIG) and laser welding. A standardized end-to-end joint configuration of the orthodontic wire material in spring hard quality was used. The joints were made using five different methods: brazing (soldering > 450 degrees C) with universal silver solder, two TIG, and two laser welders. Laser parameters and welding conditions were used according to the manufacturers' guidance. The tensile strengths were measured with a universal testing machine (Zwick 005). The microhardness measurements were carried out with a hardness tester (Zwick 3202). Data were analysed using one-way analysis of variance and Bonferroni's post hoc correction (P TIG or laser welding were found. The highest means were observed for TIG welding (699-754 MPa). Laser welding showed a significantly lower mean tensile strength (369-520 MPa) compared with TIG welding. Significant differences (P welded area. The mean microhardness differed significantly between brazing (1.99 GPa), TIG (2.22-2.39 GPa) and laser welding (2.21-2.68 GPa). For orthodontic purposes, laser and TIG welding are solder-free alternatives to joining metal. TIG welding with a lower investment cost is comparable with laser welding. However, while expensive, the laser technique is a sophisticated and simple method.

  20. Modification of Inclusions in Molten Steel by Mg-Ca Transfer from Top Slag: Experimental Confirmation of the `Refractory-Slag-Metal-Inclusion (ReSMI)' Multiphase Reaction Model

    Science.gov (United States)

    Shin, Jae Hong; Park, Joo Hyun

    2017-12-01

    High-temperature experiments and Refractory-Slag-Metal-Inclusion (ReSMI) multiphase reaction simulations were carried out to determine the effect of the ladle slag composition on the formation behavior of non-metallic inclusions in molten steel. Immediately after the slag-metal reaction, magnesium migrated to the molten steel and a MgAl2O4 spinel inclusion was formed due to a reaction between magnesium and alumina inclusions. However, the spinel inclusion changed entirely into a liquid oxide inclusion via the transfer of calcium from slag to metal in the final stage of the reaction. Calcium transfer from slag to metal was more enhanced for lower SiO2 content in the slag. Consequently, the spinel inclusion was modified to form a liquid CaO-Al2O3-MgO-SiO2 inclusion, which is harmless under steelmaking conditions. The modification reaction was more efficient as the SiO2 content in the slag decreases.

  1. Thermal Cyclability of Reactive Air Braze Seals in Anode Supported Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, John S.; Darsell, Jens T.; Coyle, Christopher A.; Birnbaum, Jerome C.; Weil, K. Scott

    2004-12-31

    The popularity of anode-supported solid oxide fuel cells (SOFC) has increased in tandem with the ability to fabricate thinner gas-tight yttrium-stabilized zirconia (YSZ) electrolyte layers, which can now be routinely produced on the order of 7 to 10 μm thick. While this has significantly improved power output and decreased the required fuel cell operating temperatures, the ability to reliably seal fuel cells remains a concern. The seals must be hermetic and be robust enough to retain their hermeticity even under the extreme operating conditions of SOFCs. Perhaps the largest contributor to stresses experienced by the seal is the fact that the SOFC is an assembly of many different materials with different thermal expansion properties. Although every effort is made to minimize thermal expansion mismatches across the seals, the stresses developed during thermal cycling still jeopardize seal integrity. Reactive air brazing (RAB), a method of joining that employs a metallic, and therefore non-brittle, seal material has been used to seal electrolyte/anode bilayers, such as those in anode-supported SOFCs, to Crofer-22 alloy. The results of rupture strength testing will be reported for as-brazed and thermally cycled samples and the effect of thermal cycling on the RAB seal microstructure will be shown

  2. Design, fabrication, and performance of brazed, graphite electrode, multistage depressed collectors with 500-W, continuous wave, 4.8- to 9.6-GHz traveling-wave tubes

    Science.gov (United States)

    Ramins, Peter; Ebihara, Ben

    1989-03-01

    A small, isotropic graphite electrode, multistage depressed collector (MDC) was designed, fabricated, and evaluated in conjunction with a 500-W, continuous wave (CW), 4.8- to 9.6-GHz traveling-wave tube (TWT). The carbon electrode surfaces were used to improve the TWT overall efficiency by minimizing the secondary electron emission losses in the MDC. The design and fabrication of the brazed graphite MDC assembly are described. The brazing technique, which used copper braze filler metal, is compatible with both vacuum and the more commonly available hydrogen atmosphere brazing furnaces. The TWT and graphite electrode MCC bakeout, processing, and outgassing characteristics were evaluated and found to be comparable to TWT's equipped with copper electrode MDC's. The TWT and MDC performance was optimized for broadband CW operation at saturation. The average radiofrequency (RF), overall, and MDC efficiencies were 14.9, 46.4, and 83.6 percent, respectively, across the octave operating band. A 1500-hr CW test, conducted without the use of an appendage ion pump, showed no gas buildup and excellent stability of the electrode surfaces.

  3. Corrosion Mechanisms in Brazed Al-Base Alloy Sandwich Structures as a Function of Braze Alloy and Process Variables

    Science.gov (United States)

    2013-02-01

    Welding , Brazing, and Soldering (ASM International: Materials Park, Ohio, 1993) p. 937. 3. A.K. Bhattamishra and K. Lai, "Microstructural studies on the...TCT6) condition, c) UNS A96061 T6 + UNS A94047 foil wedge. 47 ^ mtsst k\\ ’J%jry~z & ■^ KC t ^\\T iH ^^ >*^ .CH\\ WBSSS^SK ;s * iW >flLr4w...at an International Conference for Braze or Weld Sandwich work One A.B. Campbell Award for best paper for an author under 35 years of age iv

  4. Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

    Science.gov (United States)

    Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

    2017-05-01

    The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments.

  5. Microwave-assisted brazing of alumina ceramics for electron tube ...

    Indian Academy of Sciences (India)

    Microwave-assisted brazing of alumina ceramics for electron tube applications. MAYUR SHUKLA1,2, SUMANA GHOSH2,∗, NANDADULAL DANDAPAT2, ASHIS K MANDAL2 and VAMSI K BALLA2. 1Academy of Scientific and Innovative Research (AcSIR), CSIR—-Central Glass and Ceramic Research Institute,.

  6. Joining of beryllium by braze welding technique: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Banaim, P.; Abramov, E. [Ben-Gurion Univ. of the Negev, Beersheba (Israel); Zalkind, S.; Eden, S.

    1998-01-01

    Within the framework of some applications, there is a need to join beryllium parts to each other. Gas Tungsten Arc Braze Welds were made in beryllium using 0.3 mm commercially Aluminum (1100) shim preplaced at the joint. The welds exhibited a tendency to form microcracks in the Fusion Zone and Heat Affected Zone. All the microcracks were backfilled with Aluminum. (author)

  7. Enhanced corrosion protection by microstructural control of aluminium brazing sheet

    NARCIS (Netherlands)

    Norouzi Afshar, F.

    2013-01-01

    Aluminium brazing sheet is a sandwich material made out of two aluminium alloys (AA4xxx/AA3xxx) and is widely used in automotive heat exchangers. One of the main performance criteria for heat exchanger units is the lifetime of the product. The lifetime of the heat exchanger units is determined by

  8. Interfacial microstructure and strength of diffusion brazed joint ...

    Indian Academy of Sciences (India)

    TECS

    Abstract. Joining of composite, Al2O3–TiC, with heat-resistant 9Cr1MoV steel, was carried out by diffusion brazing technology, using a combination of Ti, Cu and Ti as multi-interlayer. The interfacial strength was measured by shear testing and the result was explained by the fracture morphology. Microstructural charac-.

  9. Corrosion in artificial saliva of a Ni-Cr-based dental alloy joined by TIG welding and conventional brazing.

    Science.gov (United States)

    Matos, Irma C; Bastos, Ivan N; Diniz, Marília G; de Miranda, Mauro S

    2015-08-01

    Fixed prosthesis and partial dental prosthesis frameworks are usually made from welded Ni-Cr-based alloys. These structures can corrode in saliva and have to be investigated to establish their safety. The purpose of this study was to evaluate the corrosion behavior of joints joined by tungsten inert gas (TIG) welding and conventional brazing in specimens made of commercial Ni-Cr alloy in Fusayama artificial saliva at 37°C (pH 2.5 and 5.5). Eighteen Ni-Cr base metal specimens were cast and welded by brazing or tungsten inert gas methods. The specimens were divided into 3 groups (base metal, 2 welded specimens), and the composition and microstructure were qualitatively evaluated. The results of potential corrosion and corrosion current density were analyzed with a 1-way analysis of variance and the Tukey test for pairwise comparisons (α=.05). Base metal and tungsten inert gas welded material showed equivalent results in electrochemical corrosion tests, while the air-torched specimens exhibited low corrosion resistance. The performance was worst at pH 2.5. These results suggest that tungsten inert gas is a suitable welding process for use in dentistry, because the final microstructure does not reduce the corrosion resistance in artificial saliva at 37°C, even in a corrosion-testing medium that facilitates galvanic corrosion processes. Moreover, the corrosion current density of brazed Ni-Cr alloy joints was significantly higher (Pwelded joints. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  10. Refractory Materials for Flame Deflector Protection System Corrosion Control: Refractory Ceramics Literature Survey

    Science.gov (United States)

    Calle, Luz Marina; Hintze, Paul E.; Parlier, Christopher R.; Curran, Jerome P.; Kolody, Mark; Perusich, Stephen; Whitten, Mary C.; Trejo, David; Zidek, Jason; Sampson, Jeffrey W.; hide

    2009-01-01

    Ceramics can be defmed as a material consisting of hard brittle properties produced from inorganic and nonmetallic minerals made by firing at high temperatures. These materials are compounds between metallic and nonmetallic elements and are either totally ionic, or predominately ionic but having some covalent character. This definition allows for a large range of materials, not all applicable to refractory applications. As this report is focused on potential ceramic materials for high temperature, aggressive exposure applications, the ceramics reviewed as part of this report will focus on refractory ceramics specifically designed and used for these applications. Ceramic materials consist of a wide variety of products. Callister (2000) 1 characterized ceramic materials into six classifications: glasses, clay products, refractories, cements, abrasives, and advanced ceramics. Figure 1 shows this classification system. This review will focus mainly on refractory ceramics and cements as in general, the other classifications are neither applicable nor economical for use in large structures such as the flame trench. Although much work has been done in advanced ceramics over the past decade or so, these materials are likely cost prohibitive and would have to be fabricated off-site, transported to the NASA facilities, and installed, which make these even less feasible. Although the authors reviewed the literature on advanced ceramic refractories 2 center dot 3 center dot 4 center dot 5 center dot 6 center dot 7 center dot 8 center dot 9 center dot 10 center dot 11 center dot 12 after the review it was concluded that these materials should not be ' the focus of this report. A review is in progress on materials and systems for prefabricated refractory ceramic panels, but this review is focusing more on typical refractory materials for prefabricated systems, which could make the system more economically feasible. Refractory ceramics are used for a wide variety of applications

  11. Development of improved refractories

    Energy Technology Data Exchange (ETDEWEB)

    Wereszczak, A.A.; Ferber, M.K.; Liu, K.C. [Oak Ridge National Lab., TN (United States); Moore, R.E. [Univ. of Missouri, Rolla, MO (United States)

    1997-04-01

    The goal of the proposed project is to provide expertise and facilities for the high temperature mechanical properties characterization of refractory materials which are of interest to the US DOE`s Office of Industrial Technologies Advanced Industrial Materials Project. Initially the project would establish dedicated refractory testing facilities which would be capable of generating representative engineering creep and high temperature modulus of elasticity (MOE) data to a temperature of 3300{degrees}F (1815{degrees}C) in ambient air. The generated engineering creep and MOE data would serve R&D requirements of refractories-manufacturers and its glass-manufacturer end-users and designers. The relevance of this effort to the refractory and glass-making industries would be ensured by coordinating the research activities through a membership with Alfred University`s Center for Glass Research (CGR) Satellite Center at the University of Missouri-Rolla (UMR), an NSF Center. Valid engineering creep and high temperature MOE data currently do not exist for almost all commercial refractories. Refractory end-users such as glass-manufacturers require such data for efficient and economical design of their various glass-melting furnace superstructures (e.g., furnace crowns). Refractories in glass production furnaces may be subjected to extreme temperatures as high as 3200{degrees}F (1760{degrees}C). With the simultaneous imposition of mechanical and thermal stresses, creep deformation of the refractory material will assuredly occur as a consequence. Designers must ensure that the structural integrity is maintained, so these high temperature deformations must be considered for successful glass furnace superstructure design. These criteria can only be satisfied with the utilization of representative engineering creep and high temperature MOE data for the refractory materials that are chosen for the design of the refractory superstructures.

  12. HIGH TEMPERATURE REFRACTORY COATING FOR GRAPHITE MOLDS

    Science.gov (United States)

    Stoddard, S.D.

    1958-10-21

    An improved foundry mold coating for use with graphite molds used in the casting of uranium is presented. The refractory mold coating serves to keep the molten uranium from contact with graphite of the mold and thus prevents carbon pickup by the molten metal. The refractory coating is made by dry mixing certain specific amounts of aluminum oxide, bentonite, Tennessee ball clay, and a soluble silicate salt. Water is then added to the mixture and the suspension thus formed is applied by spraying onto the mold.

  13. An unconventional set-up for fluxless brazing of aluminium

    CERN Document Server

    Loos, Robert

    1999-01-01

    In order to successfully braze aluminium alloy assemblies without the use of oxide-removing fluxes, an evironment with very low contaminant level is mandatory. This is mostly achieved by using a vacuum furnace. Brazing under inert gas of sufficient purity is also possible. The method reported upon here makes use of a stainless steel bag which can enter a traditional air furnace. The bag is evacuated, giving a well distributed mechanical pressure on the parts to join. The intrinsic handicap of poor vacuum is compensated by regular inert gas flushing, even at high temperatures. The set-up works rather well, and the idea is believed to yield a valuable strategic and economic option, for the realization of special equipment as well as for prototyping work. We intend to use the principle for the CMS Preshower cooling screens.

  14. Analysis of Laser-Brazed Diamond Particle Microstructures

    Directory of Open Access Journals (Sweden)

    Zhibo YANG

    2015-11-01

    Full Text Available Brazing diamond particles to a steel substrate using Ni-based filler alloy was carried out via laser in an argon atmosphere. The brazed diamond particles were detected by scanning electron microscope (SEM, X-ray diffraction (XRD, and energy dispersive X-ray spectroscopy (EDS. The formation mechanism of carbide layers was discussed. All the results indicated that a high-strength bond between the diamond particles and the steel substrate was successfully realized. The chromium in the Ni-based alloy segregated preferentially to the surfaces of the diamonds to form a chromium-rich reaction product, and the bond between the alloy and the steel substrate was established through a cross-diffusion of iron and Ni-based alloy.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9626

  15. Separation and Sealing of a Sample Container Using Brazing

    Science.gov (United States)

    Bar-Cohen, Yoseph; Rivellini, Tommaso P.; Wincentsen, James E.; Gershman, Robert

    2007-01-01

    A special double-wall container and a process for utilizing the container are being developed to enable (1) acquisition of a sample of material in a dirty environment that may include a biological and/or chemical hazard; (2) sealing a lid onto the inner part of the container to hermetically enclose the sample; (3) separating the resulting hermetic container from the dirty environment; and (4) bringing that hermetic container, without any biological or chemical contamination of its outer surface, into a clean environment. The process is denoted S(exp 3)B (separation, seaming, and sealing using brazing) because sealing of the sample into the hermetic container, separating the container from the dirty environment, and bringing the container with a clean outer surface into the clean environment are all accomplished simultaneously with a brazing operation.

  16. Development of reactive-air-brazing as a joining technology for material combinations of the high temperature solid oxide fuel cell; Weiterentwicklung des Reactive-Air-Brazing (Reaktionsloeten an Luft) als Fuegetechnik fuer Werkstoffkombinationen der Hochtemperaturbrennstoffzelle

    Energy Technology Data Exchange (ETDEWEB)

    Koppitz, T.; Federmann, D.; Reichle, S.; Reisgen, U.; Remmel, J.; Zerfass, H.R. [Forschungszentrum Juelich GmbH (Germany)

    2007-07-01

    REactive air brazing is a promising joining technology. A silver braze is used for brazing of the basic materials, i.e. ferritic Cr steel (Crofer22ALPU) and 8YSZ electrolyte resp. a ceramic Al2O3/MgO insulating layer. The silver braze contains additives to ensure wettability, to improve the solidification morphology, and to suppress weld porosity. The contribution presents current results of investigations in this field and outlines the potential of the technology. (orig.)

  17. Colectomy for refractory constipation

    DEFF Research Database (Denmark)

    Raahave, Dennis; Loud, Franck Bjørn; Christensen, Elsebeth

    2010-01-01

    OBJECTIVE: This study evaluated the type of colectomy, postoperative complications, functional results, and satisfaction in patients with constipation refractory to conservative therapy. Further, colonic transit time (CTT), faecal load (coprostasis), and colon length (redundancies) were compared...

  18. Gas Shielding Technology for Welding and Brazing

    Science.gov (United States)

    Nunes, Arthur J.; Gradl, Paul R.

    2012-01-01

    Welding is a common method that allows two metallic materials to be joined together with high structural integrity. When joints need to be leak-tight, light-weight, or free of contaminant-trapping seams or surface asperities, welding tends to be specified. There are many welding techniques, each with its own advantages and disadvantages. Some of these techniques include Forge Welding, Gas Tungsten Arc Welding, Friction Stir Welding, and Laser Beam Welding to name a few. Whichever technique is used, the objective is a structural joint that meets the requirements of a particular component or assembly. A key practice in producing quality welds is the use of shielding gas. This article discusses various weld techniques, quality of the welds, and importance of shielding gas in each of those techniques. Metallic bonds, or joints, are produced when metals are put into intimate contact. In the solid-state "blacksmith welding" process, now called Forge Welding (FOW), the site to be joined is pounded into intimate contact. The surfaces to be joined usually need to be heated to make it easier to deform the metal. The surfaces are sprinkled with a flux to melt surface oxides and given a concave shape so that surface contamination can be squeezed out of the joint as the surfaces are pounded together; otherwise the surface contamination would be trapped in the joint and would weaken the weld. In solid-state welding processes surface oxides or other contamination are typically squeezed out of the joint in "flash."

  19. 75 FR 52037 - Welding, Cutting and Brazing Standard; Extension of the Office of Management and Budget's (OMB...

    Science.gov (United States)

    2010-08-24

    ... Occupational Safety and Health Administration Welding, Cutting and Brazing Standard; Extension of the Office of... the information collection requirements contained in the Welding, Cutting and Brazing Standard (29 CFR..., cutting and brazing are performed. The purpose of the information is to ensure that employers evaluate...

  20. 78 FR 53159 - Standard for Welding, Cutting, and Brazing; Extension of the Office of Management and Budget's...

    Science.gov (United States)

    2013-08-28

    ... Occupational Safety and Health Administration Standard for Welding, Cutting, and Brazing; Extension of the..., Cutting, and Brazing (29 CFR Part 1910, Subpart Q). The information collected is used by employers and workers whenever welding, cutting, and brazing are performed. The purpose of the information is to ensure...

  1. 49 CFR 178.55 - Specification 4B240ET welded or brazed cylinders.

    Science.gov (United States)

    2010-10-01

    ... repairs to longitudinal joints is permitted. (3) Welding procedures and operators must be qualified in... 49 Transportation 2 2010-10-01 2010-10-01 false Specification 4B240ET welded or brazed cylinders... SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.55 Specification 4B240ET welded or brazed...

  2. Economic solar-panel production by infrared brazing; Wirtschaftliche Herstellung von Solarabsorbern durch Infrarotloeten

    Energy Technology Data Exchange (ETDEWEB)

    Fuessel, U.; Frenz, C.A.; Six, S. [Technische Univ. Dresden (Germany)

    2007-07-01

    Infrared brazing is a new technology for solar absorber construction which reduces the joining time and improves the heat transfer from the absorber sheet to the pipe register. The solar-selective layer remains undamaged, heat transfer into the absorber sheets is reduced, and production of full-surface absorbers becomes possible. In all, infrared brazing will improve the efficiency of the absorber. (orig.)

  3. Silica passivation layer on aluminium brazing sheets

    OpenAIRE

    Schäuble, Kathrin

    2010-01-01

    Abstract The request for more efficient fuel economy to save raw materials and to reduce air pollution becomes more and more crucial in the automotive industry. To fulfil this demand by weight reduction, conventional materials such as steel and copper are replaced by light metals. Due to its beneficial material properties e. g. low density, high strength, good formability and high thermal conductivity, aluminium becomes a frequently used candidate. Particularly in the heat-exchanger industry ...

  4. Experimental study of W-Eurofer laser brazing for divertor application

    Energy Technology Data Exchange (ETDEWEB)

    Munez, C.J., E-mail: claudio.munez@urjc.es [Dept. de Tecnologia Mecanica, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, Mostoles 28933, Madrid (Spain); Garrido, M.A. [Dept. de Tecnologia Mecanica, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, Mostoles 28933, Madrid (Spain); Rams, J.; Urena, A. [Dept. de Ciencia e Ingenieria de Materiales, ESCET, Universidad Rey Juan Carlos, C/Tulipan s/n, Mostoles 28933, Madrid (Spain)

    2011-11-15

    Highlights: > Laser brazing system as a suitable technique to joint W and Eurofer alloys. > High residual stresses at the bonding were produced. > Laser brazing of powder metallurgy W alloys added porosity in the solidified pool. > The CSM methodology as a suitable technique to discriminate zones of welding joints. - Abstract: This work can be considered as a preliminary evaluation of the potential of laser brazing for joining tungsten based alloys to reduced activation ferritic-martensitic steels (Eurofer). Brazing of tungsten and EUROFER alloys using a 55Ni-45Ti alloy as a brazer and a high power diode laser (HPDL) as a power source has been investigated. The brazed joints showed solidified pools with good superficial aspect and a high degree of wettability with the both parent sheets, presumably because of the active effect of titanium. Metallurgical brazeability was investigated and nanoindentation measurements were done to evaluate local hardening and stiffness effects associated to dilution phenomena.

  5. Experimental and thermodynamic assessment of beryllium-replacement materials for CANDU brazed joints

    Energy Technology Data Exchange (ETDEWEB)

    Potter, K.N.; Ferrier, G.A.; Corcoran, E.C., E-mail: Kieran.Potter@rmc.ca [Royal Military College of Canada, Kingston ON, (Canada); Dimayuga, F.C. [Canadian Nuclear Laboratories, Chalk River, ON (Canada)

    2015-07-01

    Currently, appendages are joined to CANDU fuel elements via a brazing process, with beryllium as the filler material. A potential reduction in the occupational limit on airborne beryllium particulates has motivated research into alternative brazing materials. To this end, the Canadian nuclear industry has funded an initiative to identify and evaluate the suitability of several candidate brazing materials. This work describes contributions toward the assessment of alternative brazing materials from the Royal Military College of Canada (RMCC). An impact testing method was developed to evaluate the mechanical strength of candidate braze joints.Thermodynamic modelling was performed to predict the aqueous behaviour of each candidate material in CANDU coolant conditions characteristic of reactor shutdown, and corrosion experiments are underway to support modelling predictions.The results of these activities will assist in selecting a suitable replacement material for beryllium. (author)

  6. Comparative Investigation on Brazing Behavior, Compressive Strength, and Wear Properties of Multicrystalline CBN Abrasive Grains

    Directory of Open Access Journals (Sweden)

    Wen-Feng Ding

    2014-05-01

    Full Text Available In order to fabricate the abrasive wheels with good grain self-sharpening capacity, two types of multicrystalline CBN grains, that is, polycrystalline CBN (PCBN and binderless CBN (BCBN, were brazed using Cu-Sn-Ti alloy, respectively. Comparative investigation on the brazing interface, compressive strength, and wear properties of the different grains was carried out. Results obtained show that the PCBN grains have more intricate reaction, more complicated resultants, and thicker reaction layer than the BCBN counterparts under the identical brazing conditions. Though the average compressive strength of the PCBN grains is similar to that of BCBN ones, stronger self-sharpening action by virtue of the microfracture behavior takes place with BCBN grains during grinding. As a consequence, compared to the brazed PCBN wheels and the conventional monocrystalline CBN (MCBN ones, longer service life is obtained for the brazed BCBN wheels.

  7. Management of refractory epilepsy.

    Science.gov (United States)

    Muñana, Karen R

    2013-05-01

    The term refractory epilepsy is utilized in veterinary medicine to describe a condition in which an animal with epilepsy fails to attain satisfactory seizure control or suffers intolerable side effects despite appropriate therapy with conventional antiepileptic drugs. Refractory epilepsy is an important problem in small animal practice as it occurs in approximately one-third of dogs with epilepsy. Consequently, there is much interest in identifying ways to more effectively treat this population of animals. More than a dozen new antiepileptic drugs have been approved for humans over the last 2 decades, and several of these drugs, including gabapentin, zonisamide, levetiracetam, and pregabalin, have been evaluated for the treatment of refractory seizures in veterinary patients. Nonmedical methods to treat poorly controlled epilepsy are also being explored. The 2 alternative forms of therapy that have shown the most promise in humans with epilepsy are electrical stimulation of the brain and dietary modification, both of which have also been evaluated in dogs. This overview summarizes the available data on pharmacologic as well as nonmedical treatment options for dogs and cats with refractory epilepsy. Although many forms of therapy are currently being utilized in clinical practice, our knowledge of the safety and efficacy of these treatments is limited. Additional randomized controlled trials are needed to better evaluate these novel therapies for refractory epilepsy in dogs and cats. © 2013 Elsevier Inc. All rights reserved.

  8. Refractory gastroesophageal reflux disease

    Directory of Open Access Journals (Sweden)

    Joaquim Prado P. Moraes-Filho

    2012-12-01

    Full Text Available CONTEXT: Gastroesophageal reflux disease (GERD is a condition which develops when the reflux of stomach contents causes troublesome symptoms and/or complications. Its pathophysiology, diagnosis and treatment have frequently been analyzed but it is interesting to review some aspects of the GERD refractory patients to the proton pump inhibitors treatment. The treatment encompasses behavioral measures and pharmacological therapy. The majority of the patients respond well to proton pump inhibitors treatment but 20%-42% of them may not do so well. Patients who are unresponsible to 4-8 weeks' treatment with proton pump inhibitors (omeprazole, pantoprazole, rabeprazole, lansoprazole, esomeprazole, pantoprazole-Mg might have so-called refractory GERD. RESULTS: In some cases the patients are not real refractory because either they do not have GERD or the disease was not correctly treated, but the term refractory is still employed. Although debatable, the Brazilian GERD Consensus based upon evidences recommends as first step in the diagnosis, the upper digestive endoscopy to exclude the diagnosis of peptic ulcer and cancer and in some cases identify the presence of esophageal mucosa erosions. CONCLUSIONS: The main causes of the so-called refractory GERD are: (1 functional heartburn; (2 low levels of adherence to proton pump inhibitors treatment; (3 inadequate proton pump inhibitors dosage; (4 wrong diagnosis; (5 co-morbidities and pill-induced esophagitis; (6 genotypic differences; (7 nonacid gastroesophageal reflux; (8 autoimmune skin diseases; (9 eosinophilic esophagitis.

  9. Compatibility of refractory materials for nuclear reactor poison control systems

    Science.gov (United States)

    Sinclair, J. H.

    1974-01-01

    Metal-clad poison rods have been considered for the control system of an advanced space power reactor concept studied at the NASA Lewis Research Center. Such control rods may be required to operate at temperatures of about 140O C. Selected poison materials (including boron carbide and the diborides of zirconium, hafnium, and tantalum) were subjected to 1000-hour screening tests in contact with candidate refractory metal cladding materials (including tungsten and alloys of tantalum, niobium, and molybdenum) to assess the compatibility of these materials combinations at the temperatures of interest. Zirconium and hafnium diborides were compatible with refractory metals at 1400 C, but boron carbide and tantalum diboride reacted with the refractory metals at this temperature. Zirconium diboride also showed promise as a reaction barrier between boron carbide and tungsten.

  10. High-Density Infrared Surface Treatments of Refractories

    Energy Technology Data Exchange (ETDEWEB)

    Tiegs, T.N.

    2005-03-31

    Refractory materials play a crucial role in all energy-intensive industries and are truly a crosscutting technology for the Industries of the Future (IOF). One of the major mechanisms for the degradation of refractories and a general decrease in their performance has been the penetration and corrosion by molten metals or glass. Methods and materials that would reduce the penetration, wetting, and corrosive chemistry would significantly improve refractory performance and also maintain the quality of the processed liquid, be it metal or glass. This report presents the results of an R&D project aimed at investigating the use of high-density infrared (HDI) heating to surface treat refractories to improve their performance. The project was a joint effort between Oak Ridge National Laboratory (ORNL) and the University of Missouri-Rolla (UMR). HDI is capable of heating the near-surface region of materials to very high temperatures where sintering, diffusion, and melting can occur. The intended benefits of HDI processing of refractories were to (1) reduce surface porosity (by essentially sealing the surface to prevent liquid penetration), (2) allow surface chemistry changes to be performed by bonding an adherent coating onto the underlying refractory (in order to inhibit wetting and/or improve corrosion resistance), and (3) produce noncontact refractories with high-emissivity surface coatings.

  11. Plasmonic properties of refractory titanium nitride

    Science.gov (United States)

    Catellani, Alessandra; Calzolari, Arrigo

    2017-03-01

    The development of plasmonic and metamaterial devices requires the research of high-performance materials alternative to standard noble metals. Renewed as a refractory stable compound for durable coatings, titanium nitride has recently been proposed as an efficient plasmonic material. Here, by using a first-principles approach, we investigate the plasmon dispersion relations of TiN bulk and we predict the effect of pressure on its optoelectronic properties. Our results explain the main features of TiN in the visible range and prove a universal scaling law which relates its mechanical and plasmonic properties as a function of pressure. Finally, we address the formation and stability of surface-plasmon polaritons at different TiN-dielectric interfaces proposed by recent experiments. The unusual combination of plasmonics and refractory features paves the way for the realization of plasmonic devices able to work at conditions not sustainable by the usual noble metals.

  12. Processes for preparing novel baddeleyite refractory articles

    Energy Technology Data Exchange (ETDEWEB)

    McGarry, Ch.N.; Stunis, J.; Wehrenberg, Th.M.

    1984-07-24

    A novel process for fabricating novel high zirconia content refractory articles directly from novel sinterable compositions including as the major ingredient thereof baddeleyite ore concentrates thereby reducing costs. Appropriate additives, particularly zircon, further provide enhanced resistance to thermal shock damage. Plasticizers, binders and other processing aids are identified for press forming exemplary compositions into continuous casting nozzles, shrouds and other ceramic products typically used in the processing of molten steel, specialty metals and glass.

  13. [Treatment of refractory ascites].

    Science.gov (United States)

    Martínez, Javier; Albillos, Agustín

    2014-07-01

    Ascites is a common complication of hepatic cirrhosis and portal hypertension. Patients present systemic and splanchnic circulation disorders, which cause central hypovolemia and arterial hypotension, with the subsequent activation of vasoconstrictor systems and increased renal reabsorption of sodium and water. Approximately 5%-10% of patients present refractory ascites. Refractory ascites is considered when it is not controllable with standard dietary (sodium restriction) and diuretic (furosemide up to 160 mg a day and spironolactone up to 400mg a day) treatment or when patients present adverse effects due to diuretics that impede their administration at optimum dosages. The current therapeutic options for these patients are repeated evacuative paracentesis and the percutaneous intrahepatic portosystemic shunt. Despite these treatments, refractory ascites has a poor prognosis; patients should therefore be assessed for liver transplantation. Copyright © 2014 Elsevier España, S.L. All rights reserved.

  14. The Joint Strength and Fracture Mechanisms of TC4/TC4 and TA0/TA0 Brazed with Ti-25Cu-15Ni Braze Alloy

    Science.gov (United States)

    Zou, Zhihuan; Zeng, Fanhao; Wu, Haobo; Liu, Jian; Li, Yi; Gu, Yi; Yuan, Tiechui; Zhang, Fuqin

    2017-05-01

    In this paper, Ti-25Cu-15Ni (mass ratio) braze alloys were prepared by vacuum arc melting. Additionally, the TA0 pure titanium and TC4 titanium alloy were brazed with the Ti-25Cu-15Ni braze alloy at 960, 980, 1000, 1020, and 1040 °C. The effects of the braze temperature on the tensile strength of the TA0 and TC4 joints and their fracture mechanisms were studied. The maximum tensile strength of the TA0 joints of 219.9 ± 0.1 MPa was achieved at a brazing temperature of 980 °C, and the maximum tensile strength of the TC4 joints of 832.9 ± 0.1 MPa was achieved at the same brazing temperature. These results indicate that their ideal joint strength is comparable. According to the fractography results of the TA0 joints, a mixed fracture morphology is indicated. The TA0 fracture surface is dominated by cleavage fracture with a small contribution from ductile fracture. The TC4 joint fracture arises from cleavage.

  15. "A High Speed Laser Profiling Device for Refractory Lininig Thickness Measurements In a Gasifier with Cross-Cut to the Metals, Forest Products, Chemical and Power Generation Industries"

    Energy Technology Data Exchange (ETDEWEB)

    Michel Bonin; Tom Harvill; Jared Hoog; Don Holve; Alan Alsing; Bob Clark; Steve Hrivnak

    2007-11-01

    Process Metrix began this project with the intent of modifying an existing ranging system and combining the same with a specially designed optical scanner to yield three dimensional range images that could be used to determine the refractory lining thickness in a gasifier. The goal was to make these measurements during short outages while the gasifier was at or near operating temperature. Our initial estimates of the photon counts needed for the modulation-based range finder were optimistic, and we were forced to undertake a redesign of the range finder portion of the project. This ultimately created significant and unanticipated time delays that were exacerbated when Acuity Technologies, the subcontractor responsible for delivering the redesigned range finder, failed to deliver electrical components capable of meeting the specific range error requirements needed for accurate lining thickness measurement. An extensive search for an alternate, off-the-shelf solution was unsuccessful, and Process Metrix was forced to undertake the electronics development internally without project funds. The positive outcome of this effort is a documented set of range finder electronics that have exceptional accuracy, simplicity, temperature stability and detection limit; in sum a package perfectly suited to the measurement requirements and within our control. It is unfortunate yet understandable, given the time delays involved in reaching this milestone, that the Department of Energy decided not to continue the project to completion. The integration of this electronics set into the optomechanical hardware also developed within the scope of the project remains as follow-on project that Process Metrix will finish within the calendar year 2008. Testing in the gasifier is, at this point, not certain pending the award of additional funding needed for field trials. Eastman, our industrial partner in this project, remains interested in evaluating a finished system, and working together we

  16. Research for Brazing Materials of High-Temperature Thermoelectric Modules with CoSb3 Thermoelectric Materials

    Science.gov (United States)

    Lee, Yu Seong; Kim, Suk Jun; Kim, Byeong Geun; Lee, Soonil; Seo, Won-Seon; Kim, Il-Ho; Choi, Soon-Mok

    2017-05-01

    Metallic glass (MG) can be a candidate for an alternative brazing material of high-temperature thermoelectric modules, since we can expect both a lower brazing temperature and a high operating temperature for the junction from the MG brazers. Another advantage of MG powders is their outstanding oxidation resistance, namely, high-temperature durability in atmosphere. We fabricated three compositions of Al-based MGs—Al-Y-Ni, Al-Y-Ni-Co, and Al-Y-Ni-Co-La—by using the melt spinning process, and their T gs were 273°C, 264°C, and 249°C, respectively. The electrical resistivity of the Al-Y-Ni MG ribbon dropped significantly after annealing at 300°C. The electrical resistivity of crystallized Al-Y-Ni reduced down to 0.03 mΩ cm, which is an order of magnitude lower than that of the amorphous one. After the MG ribbons were pulverized to sub-100 μm, the average particle size was about 400 μm.

  17. Metal-Matrix Composite Parts With Metal Inserts

    Science.gov (United States)

    Majkowski, T.; Kashalikar, U.

    1995-01-01

    Developmental fabrication process produces metal-matrix composite (MMC) parts with integral metal inserts. With inserts, MMC parts readily joined to similar parts by use of brazing, welding, or mechanical fasteners. Process conceived to make strong, lightweight components of structures erected in outer space. Also useful on Earth, in such automotive parts as rocker arms, cylinder liners, and pistons. Potential industrial applications include parts subjected to high stresses at high temperatures, as in power-generation, mining, and oil-drilling equipment.

  18. Dynamic Testing of Gasifier Refractory

    Energy Technology Data Exchange (ETDEWEB)

    Michael D. Mann; Wayne S. Seames; Devdutt Shukla; Xi Hong; John P. Hurley

    2005-12-01

    The University of North Dakota (UND) Chemical Engineering Department in conjunction with the UND Energy & Environmental Research Center (EERC) have initiated a program to examine the combined chemical (reaction and phase change) and physical (erosion) effects experienced by refractory materials under slagging coal gasification conditions. The goal of this work is to devise a mechanism of refractory loss under these conditions. The controlled-atmospheric dynamic corrodent application furnace (CADCAF) was utilized to simulate refractory/slag interactions under dynamic conditions that more realistically simulate the environment in a slagging coal gasifier than any of the static tests used previously by refractory manufacturers and researchers. High-alumina and high-chromia refractory bricks were tested using slags obtained from two solid fuel gasifiers. Testing was performed at 1475 C in a reducing atmosphere (2% H{sub 2} in N{sub 2}) The CADCAF tests show that high-chrome refractories have greater corrosion resistance than high-aluminum refractories; coal slag readily diffuses into the refractory through its grain boundaries; the refractory grains are more stable than the matrix in the tests, and the grains are the first line of defense against corrosion; calcium and alkali in the slag are more corrosive than iron; and silicon and calcium penetrate the deepest into the refractory. The results obtained from this study are preliminary and should be combined with result from other research programs. In particular, the refractory corrosion results from this study should be compared with refractories removed from commercial gasifiers.

  19. Refractory chronic migraine

    DEFF Research Database (Denmark)

    Martelletti, Paolo; Katsarava, Zaza; Lampl, Christian

    2014-01-01

    The debate on the clinical definition of refractory Chronic Migraine (rCM) is still far to be concluded. The importance to create a clinical framing of these rCM patients resides in the complete disability they show, in the high risk of serious adverse events from acute and preventative drugs...

  20. Brazed Diamond Micropowder Bur Fabricated by Supersonic Frequency Induction Heating for Precision Machining

    Science.gov (United States)

    Ma, Bojiang; Lou, Jianpeng; Pang, Qian

    2014-04-01

    The common brazed diamond micropowder bur fabricated in a vacuum furnace produces an even brazing alloy surface. The small brazed diamond grits show low outcropping from the brazing alloy surface, and the chip space between them is small. The bur shows a low grinding efficiency and poor heat dissipation. In this study, a brazed diamond micropowder bur was fabricated by supersonic frequency induction heating. The method afforded a fluctuant surface on the brazing alloy. The brazed diamond grits with an outcropping height distributed uniformly on the fluctuant surface. The fluctuant surface showed a certain chip space. These characteristics of the tool increased the grinding efficiency and decreased the temperature of the grinding arc area. The roughness R a of the ceramic tile surface trimmed by the tool cylinder was between 0.09 and 0.12 μm. In the first 90 min, the decrease in the weight of the ceramic tile ground by the tool cylinder was higher than that ground by the tool fabricated in a vacuum furnace. When the ceramic tile was cylindrically ground, the temperature of the grinding arc area measured using a thermocouple remained below 70 °C.

  1. Controlling phase formation during aluminium/steel Nd:YAG laser brazing

    Directory of Open Access Journals (Sweden)

    Rodriguez, L.

    2006-12-01

    Full Text Available The reduction of fuel consumption of internal combustion motors, imposed by the new anti-pollution and energy saving laws may be attained by reducing the weight of vehicles, introducing, for example, aluminium sections into the main steel car-body. Laser brazing is a process which can be used to perform such a junction. The main problem of welding this kind of materials combination with conventional processes is the potential formation of inter-metallic phases, which reduces the good performance of the joint. Laser brazing allows a very good control of the thermal development of the joint, with a limited precipitation of these brittle phases. This paper presents the results of a feasibility study made with ZnAl-30 as filler metal. The study shows that the type of configuration used for the assembly has a particular influence on the formation of brittle phases and consequently on the mechanical performance of the joint.

    La reducción en el consumo de combustibles fósiles y las emergentes leyes mundiales anti-contaminación, obligan a prever una reducción en el peso de los vehículos de transporte. Esta condición se puede cumplir por ejemplo, introduciendo componentes de Aluminio en el cuerpo de la carrocería principal de acero de los mencionados vehículos. El principal problema que se presenta al realizar este tipo de ensamblaje es la formación de fases íntermetálicas frágiles que pueden comprometer el buen desenvolvimiento de la unión. La soldadura con rayo láser permite un buen control de calor aportado y una formación muy limitada de este tipo de fases. Este trabajo presenta los resultados preliminares de los estudios realizados en uniones soldadas con ZnAl-30 como material de aportación. El estudio muestra que el tipo de configuración utilizada para realizar la soldadura tiene una influencia importante sobre la posibilidad de formación de estas fases ínter-metálicas.

  2. Determination of vanadium in refractory metals, steel, cast iron, alloys and silicates by extraction of an NBPHA complex from a sulphuric-hydrofluoric acid medium.

    Science.gov (United States)

    Donaldson, E M

    1970-07-01

    A method for determining up to 0.15% of vanadium in high-purity niobium and tantalum metals, cast iron, steel, non-ferrous alloys and silicates is described. The proposed method is based on the extraction of a red vanadium(V)-N-benzoyl-N-phenylhydroxylamine complex into chloroform from a sulphuric-hydrofluoric acid medium containing excess of ammonium persulphate as oxidant. The molar absorptivity of the complex is 428 l.mole(-1).mm(-5) at 475 nm, the wavelength of maximum absorption. Interference from chromium(VI) and cerium(IV) is eliminated by reduction with iron(II). Common ions, including large amounts of titanium, zirconium, molybdenum and tungsten, do not interfere.

  3. Status epilepticus: Refractory and super-refractory.

    Science.gov (United States)

    Dubey, Deepanshu; Kalita, Jayantee; Misra, Usha K

    2017-01-01

    Status epilepticus (SE) is an important neurological emergency. It is defined as seizures lasting for 5 minutes or more or recurrent seizures without recovery of consciousness to baseline between the attacks. Refractory SE (RSE) is defined as SE persisting despite sufficient dose of benzodiazepines and at least one antiepileptic drug (AED), irrespective of time. Super refractory SE (SRSE) is defined as SE that continues for 24 hours or more after the use of anesthetic therapy, including cases that recur on weaning of the anesthestic agent. RSE occurs in 23%-48% of the patients and SRSE in approximately 22% of the patients with SE. In general, RSE occurs in patients with new-onset seizures rather than in patients with chronic epilepsy. The etiology of RSE in developing countries is dominated by central nervous system (CNS) infections and head injury compared to stroke and drug withdrawal in the developed countries. The treatment of RSE and SRSE is not evidence based. Following benzodiazepines, the second line antiepileptic drugs include sodium valproate, phenytoin, levetiracetam, and anesthetic drugs such as midazolam, phenobarbital, and propofol. Most intravenous anesthetic drugs produce hypotension and respiratory suppression; therefore, patients with RSE are managed in intensive care units (ICUs). In RSE patients, electroencephalogram (EEG) burst suppression with interburst interval of 2-20 s or even flat EEG has been tried. Recently, concerns have been raised on the safety of burst suppression in RSE and SRSE. The paucity of ICUs in developing countries limits the use of these management protocols. There is a need to explore intravenous AEDs with safer cardiovascular and respiratory profile for the management of SE.

  4. Combined scale effects for effective brazing at low temperatures

    Directory of Open Access Journals (Sweden)

    Bartout D.

    2012-12-01

    Full Text Available In modern joining technology, the focus is on effective brazing and soldering of temperature sensitive materials. Here, as well as in diffusion welding processes the needed thermal energy is externally realized in the joint zone. This produces a heating of the whole joining parts, since in laminar joining the thermal energy is transported in interior by thermal conduction. An excess of critical temperatures or tolerable impact periods in wide parts of materials and respectively components is often not avoidable. This leads to thermal damages. In this point of view nanotechnology shows promising possibilities as scale effects and their resulting thermophysical effects such as melting temperature reduction and high diffusion rates can be used for providing a self-propagating high-temperature synthesis at room temperature. After ignition by an external energy source a self-propagating exothermic reaction is started. By producing a multilayer system with alternately arranged nanoscaled layers of e.g. Al and Ni the resulting thin foil can be used as heat source for melting the braze or solder material within the joining zone without any external preheating. Due to the high process velocities up to 30 m/s and the local heat input significant thermal influences on the joined parts are not detectable.

  5. Refractory rheumatoid vasculitis.

    Science.gov (United States)

    Kumar, Ashok; Goel, Anshul; Lapsiwala, Mehul; Singhal, Suman

    2016-11-01

    Systemic rheumatoid vasculitis (SRV) can develop in rheumatoid arthritis of long duration and high disease activity. It most commonly manifests as cutaneous vasculitis and mononeuritis multiplex. This can involve any organ of the body and carries very high mortality. We report a case of a young male who had rheumatoid arthritis for the past 15 years and became refractory to standard drugs and anti-TNF agents. He subsequently developed SRV, which started as mononeuritis multiplex. Disease progressed to result in gangrene of hands and feet despite receiving intravenous cyclophosphamide. Intravenous immunoglobulin and rituximab also could not provide any response. Prolonged ICU stay resulted in critical care neuromyopathy. Central nervous system vasculitis developed even after repeated infusions of intravenous immunoglobulins and at last he died of complications. In this case report, we have presented rare and chronic protracted presentation of rheumatoid vasculitis involving skin, nerves, brain and testis, which was refractory to the recommended therapies.

  6. Refractoriness in human atria

    DEFF Research Database (Denmark)

    Skibsbye, Lasse; Jespersen, Thomas; Christ, Torsten

    2016-01-01

    rhythm and chronic atrial fibrillation tissues and was neither affected by changes in frequency (1 vs. 3Hz). CONCLUSIONS: Our results suggest a preferentially voltage-dependent, rather than time-dependent, effect with respect to refractoriness at physiologically relevant rates in human atria. However...... drugs. Cardiomyocyte excitability depends on availability of sodium channels, which involves both time- and voltage-dependent recovery from inactivation. This study therefore aims to characterise how sodium channel inactivation affects refractoriness in human atria. METHODS AND RESULTS: Steady......-state activation and inactivation parameters of sodium channels measured in vitro in isolated human atrial cardiomyocytes were used to parameterise a mathematical human atrial cell model. Action potential data were acquired from human atrial trabeculae of patients in either sinus rhythm or chronic atrial...

  7. Periclase-chromite refractories from fused materials

    Energy Technology Data Exchange (ETDEWEB)

    Slovikovskii, V.V.; Eroshkina, V.I.; Kononenko, G.V.; Nechistykh, G.A.; Simonov, K.V.

    1985-11-01

    Experiments were carried out to obtain high-grade fused chromitepericlase. It is shown that during the melting of batch consisting of raw magnesite and chromite ore the process of reducing the chromite ore to metallic ferrochromium is eliminated, which adversely affects both the content of Cr/sub 2/O/sub 3/ in the fused material, and also the commercial appearance of the resulting refractories. The authors developed a technology for preparing periclase-chromite refractories with chrommite-periclase constituents. The goods obtained possess good physicoceramic properties and a low content of silicites. The articles thus prepared were used to make the linings of the most critical parts of the converters which allowed an increase to be made in the duration of campaigns for the Kivset units of 1.5-2 times.

  8. Characterization of intermetallics in aluminum to zinc coated interstitial free steel joining by pulsed MIG brazing for automotive application

    Energy Technology Data Exchange (ETDEWEB)

    Basak, Sushovan, E-mail: sushovanbasak@gmail.com [Metallurgical and Material Engineering Department, Jadavpur University, Kolkata–700032 (India); Das, Hrishikesh, E-mail: hrishichem@gmail.com [Metallurgical and Material Engineering Department, Jadavpur University, Kolkata–700032 (India); Pal, Tapan Kumar, E-mail: tkpal.ju@gmail.com [Metallurgical and Material Engineering Department, Jadavpur University, Kolkata–700032 (India); Shome, Mahadev, E-mail: mshome@tatasteel.com [Material Characterization & Joining Group, R & D, Tata Steel, Jamshedpur–831007 (India)

    2016-02-15

    In order to meet the demand for lighter and more fuel efficient vehicles, a significant attempt is currently being focused toward the substitution of aluminum for steel in the car body structure. It generates vital challenge with respect to the methods of joining to be used for fabrication. However, the conventional fusion joining has its own difficulty owing to formation of the brittle intermetallic phases. In this present study AA6061-T6 of 2 mm and HIF-GA steel sheet of 1 mm thick are metal inert gas (MIG) brazed with 0.8 mm Al–5Si filler wire under three different heat inputs. The effect of the heat inputs on bead geometry, microstructure and joint properties of MIG brazed Al-steel joints were exclusively studied and characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), electron probe micro analyzer (EPMA) and high resolution transmission electron microscopy (HRTEM) assisted X-ray spectroscopy (EDS) and selective area diffraction pattern. Finally microstructures were correlated with the performance of the joint. Diffusion induced intermetallic thickness measured by FESEM image and concentration profile agreed well with the numerically calculated one. HRTEM assisted EDS study was used to identify the large size FeAl{sub 3} and small size Fe{sub 2}Al{sub 5} type intermetallic compounds at the interface. The growth of these two phases in A2 (heat input: 182 J mm{sup −1}) is attributed to the slower cooling rate with higher diffusion time (~ 61 s) along the interface in comparison to the same for A1 (heat input: 155 J mm{sup −1}) with faster cooling rate and shorter diffusion time (~ 24 s). The joint efficiency as high as 65% of steel base metal is achieved for A2 which is the optimized parameter in the present study. - Highlights: • AA 6061 and HIF-GA could be successfully joined by MIG brazing. • Intermetallics are exclusively studied and characterized by XRD, FESEM and EPMA. • Intermetallic formation by diffusion is

  9. Refractory status epilepticus

    Directory of Open Access Journals (Sweden)

    Sanjay P Singh

    2014-01-01

    Full Text Available Refractory status epilepticus is a potentially life-threatening medical emergency. It requires early diagnosis and treatment. There is a lack of consensus upon its semantic definition of whether it is status epilepticus that continues despite treatment with benzodiazepine and one antiepileptic medication (AED, i.e., Lorazepam + phenytoin. Others regard refractory status epilepticus as failure of benzodiazepine and 2 antiepileptic medications, i.e., Lorazepam + phenytoin + phenobarb. Up to 30% patients in SE fail to respond to two antiepileptic drugs (AEDs and 15% continue to have seizure activity despite use of three drugs. Mechanisms that have made the treatment even more challenging are GABA-R that is internalized during status epilepticus and upregulation of multidrug transporter proteins. All patients of refractory status epilepticus require continuous EEG monitoring. There are three main agents used in the treatment of RSE. These include pentobarbital or thiopental, midazolam and propofol. RSE was shown to result in mortality in 35% cases, 39.13% of patients were left with severe neurological deficits, while another 13% had mild neurological deficits.

  10. Nano-Phase Powder Based Exothermic Braze Repair Technology For RCC Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Phase II project will advance innovative, cost effective and reliable nano-phase exothermic RCC joining processes (ExoBrazeTM) in order to be able to reinforce...

  11. Nano-Phase Powder Based Exothermic Braze Repair Technology For RCC Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — MRi is proposing, with its partner, Exotherm Corp (Camden, NJ) to demonstrate the feasibility of using exothermic brazing to join RCC (or C:SiC) composites to itself...

  12. An Investigation on Corrosion Behavior of a Multi-layer Modified Aluminum Brazing Sheet

    Directory of Open Access Journals (Sweden)

    Liu Wei

    2016-01-01

    Full Text Available The corrosion behavior of a multi-layer modified aluminum brazing sheet (AA4045/3003Mod./AA7072/AA4045 was investigated. The results shows that, the existence of BDP, which forms at the interface between clad and core layer during brazing, changes the corrosion form of the air side of the material from inter-granular corrosion to local exfoliation corrosion. The addition of anti-corrosion layer makes the corrosion form of the water side from inter-granular corrosion into uniform exfoliation corrosion. Compared to the normal triple-layer brazing sheet at the same thickness, the time to perforation of the modified four-layer brazing sheet is increased by more than 200%.

  13. Fluxless Brazing and Heat Treatment of a Plate-Fin Sandwich Actively Cooled Panel

    Science.gov (United States)

    Beuyukian, C. S.

    1978-01-01

    The processes and techniques used to fabricate plate-fin sandwich actively cooled panels are presented. The materials were 6061 aluminum alloy and brazing sheet having clad brazing alloy. The panels consisted of small scale specimens, fatigue specimens, and a large 0.61 m by 1.22 m test panel. All panels were fluxless brazed in retorts in heated platen presses while exerting external pressure to assure intimate contact of details. Distortion and damage normally associated with that heat treatment were minimized by heat treating without fixtures and solution quenching in an organic polymer solution. The test panel is the largest fluxless brazed and heat treated panel of its configuration known to exist.

  14. Combined Laser Beam Braze-Welding Process for Fluxless Al-Cu Connections

    OpenAIRE

    Solchenbach, Tobias; Plapper, Peter

    2013-01-01

    A combined laser beam welding and brazing process for Al-Cu connections in overlap configuration is investigated. Aluminium and copper for electric and electronic application is used for experiments without surface treatment or activation, e.g. by flux. Although Al and Cu have been considered as “not weldable”, the possibility of a thermal joining process, i.e., the weld-brazing, was proved. The inevitable formation of intermetallic compounds at the inter...

  15. Strength of vacuum brazed joints for repair; Haallfasthet hos reparationer utfoerda med vakuumloedning

    Energy Technology Data Exchange (ETDEWEB)

    Berglin, Leif [Siemens Industrial Turbomachinery AB, Finspaang (Sweden)

    2005-04-01

    Strength data are missing for braze joints. Repaired components cannot fully make use of the strength of the braze, and lifetime will be underestimated. The goal of the project was to generate material data to be able to prolong the lifetime of the components. Two different material combinations were tested, 12% Chromium steel brazed with BNi-2, and a nickel base alloy, IN792 brazed with BNi-5. Tensile testing at room temperature and elevated temperature was performed in the project. Target group is purchasers and suppliers of repaired components. A tensile test specimen with butt joint was developed in the project. The used test specimen worked well for the 12% Chromium steel. The results from testing show that proof stress and tensile strength are strongly depending on the joint gap, particularly at room temperature. High strength, close to base material strength, was achieved with joint gaps smaller than 50{mu}m. For wider joint gaps, strength was lower. Strength was approximately 25% of base material strength for joint gaps over 100{mu}m. The results can be explained by changes in microstructure. Joint gaps wider than 50{mu}m showed evidence of two-phase structure. At 500 deg C, the results also showed a connection between joint gap, microstructure and strength. The generated strength data can be used for calculations of lifetime for repaired components. Two different process errors were discovered in the manufacturing process of the brazed IN792 test specimens. The generated material data are therefor erroneous. The reason for this was two manufacturing errors. The tack welding was done with too high heat input. The surfaces of the joint gap became oxidised and the oxide hindered wetting of the braze. The second reason was that the brazing was done without the prescribed hold time at maximum temperature. The melting of the braze was therefor not completed when cooling started. As a result, the strength of the IN792 specimens was low at both temperatures.

  16. Flight/ground sample comparison relating to flight experiment M552, exothermic brazing

    Science.gov (United States)

    Heine, R. W.; Adams, C. M.; Siewert, T. A.

    1973-01-01

    Comparisons were made between Skylab and ground-based specimens of nickel and stainless steel which were vacuum brazed using silver-copper-lithium alloy with various joint configurations. It was established that the absence of gravity greatly extends the scope of brazing since capillary flow can proceed without gravity interference. There was also evidence of enhanced transport, primarily in that liquid silver copper alloy dissolves nickel to a much greater extent in the zero gravity environment.

  17. THE INFLUENCE OF BRAZING TEMPERATURE ON THE METALLOGRAPHIC MICROSTRUCTURE OF THE BONDED WELD

    Directory of Open Access Journals (Sweden)

    Andrei DIMITRESCU

    2013-05-01

    Full Text Available Since it was determined that as a result of fatigue on the brazed joints, the breakage occurs in thefiller material or in its immediate vicinity (Z.I.T.M., it is necessary to study the phenomenon in themicrostructure. The experiments have been made on alloys 3L59 samples, using as filler material the aluminumalloy L103. The brazing was made by gluing, overlapping nonstandard samples

  18. Mechanical properties of Inconel 718 and Nickel 201 alloys after thermal histories simulating brazing and high temperature service

    Science.gov (United States)

    James, W. F.

    1985-01-01

    An experimental investigation was made to evaluate two nickel base alloys (Nickel-201 and Inconel-718) in three heat treated conditions. These conditions were: (1) annealed; (2) after thermal exposure simulating a braze cycle; and (3) after a thermal exposure simulating a braze cycle plus one operational lifetime of high temperature service. For the Nickel-201, two different braze cycle temperatures were evaluated. A braze cycle utilizing a lower braze temperature resulted in less grain growth for Nickel-201 than the standard braze cycle used for joining Nickel-201 to Inconel-718. It was determined, however, that Nickel-201, was marginal for temperatures investigated due to large grain growth. After the thermal exposures described above, the mechanical properties of Nickel-201 were degraded, whereas similar exposure on Inconel-718 actually strengthened the material compared with the annealed condition. The investigation included tensile tests at both room temperature and elevated temperatures, stress-rupture tests, and metallographic examination.

  19. Investigation of the corrosion performance of different braze fillers fused onto stainless steel type 1.4401 (UNS S31600)

    Energy Technology Data Exchange (ETDEWEB)

    Wolfe, C.; Eklund, T.; Persson, O. [Alfa Laval Corporate AB, Tumba (Sweden)

    2004-07-01

    Corrosion measurements were performed on a new iron based braze filler, AlfaNova{sup 1} developed by Alfa Laval. The braze filler was fused onto stainless steel type EN 1.4401 (UNS S31600). The susceptibility to general corrosion, intergranular corrosion and pitting corrosion was evaluated by gravimetrical and electrochemical methods as well as metallographical examination of the samples. Different sample configurations were utilised, which simulate the geometry of a braze joint in a plate heat exchange. The results were compared with a selection of commercial nickel-based braze fillers. It was shown that the newly developed iron-based braze filler had similar corrosion resistance as the commercially available nickel-based fillers. It was seen that the precipitation of intermetallic phases due to melting point depressants had a governing effect on the corrosion resistance of the braze joint. (orig.)

  20. Projected Life of the SLAC Linac Braze Joints: Braze integrity and corrosion of cooling water hardware on accelerator sections

    Energy Technology Data Exchange (ETDEWEB)

    Glesener, W.F.; Garwin, E.L.; /SLAC

    2006-07-17

    The objective of this study was to ascertain the condition of braze joints and cooling water hardware from an accelerator section after prolonged use. Metallographic analysis was used to examine critical sites on an accelerator section that had been in use for more than 30 years. The end flange assembly showed no internal operational damage or external environmental effects. The cavity cylinder stack showed no internal operational damage however the internal surface was highly oxidized. The internal surface of the cooling water tubing was uniformly corroding at a rate of about 1 mil per year and showed no evidence of pitting. Tee fitting internal surfaces are corroding at non-uniform rates due to general corrosion and pitting. Remaining service life of the cooling water jacket is estimated to be about 20 years or year 2027. At this time, water supply pressure will exceed allowable fitting pressure due to corrosion of tubing walls.

  1. Refractory chronic cluster headache

    DEFF Research Database (Denmark)

    Mitsikostas, Dimos D; Edvinsson, Lars; Jensen, Rigmor H

    2014-01-01

    Chronic cluster headache (CCH) often resists to prophylactic pharmaceutical treatments resulting in patients' life damage. In this rare but pragmatic situation escalation to invasive management is needed but framing criteria are lacking. We aimed to reach a consensus for refractory CCH definition...... for clinical and research use. The preparation of the final consensus followed three stages. Internal between authors, a larger between all European Headache Federation members and finally an international one among all investigators that have published clinical studies on cluster headache the last five years...

  2. IMPROVED CORROSION RESISTANCE OF ALUMINA REFRACTORIES

    Energy Technology Data Exchange (ETDEWEB)

    John P. Hurley; Patty L. Kleven

    2001-09-30

    The initial objective of this project was to do a literature search to define the problems of refractory selection in the metals and glass industries. The problems fall into three categories: Economic--What do the major problems cost the industries financially? Operational--How do the major problems affect production efficiency and impact the environment? and Scientific--What are the chemical and physical mechanisms that cause the problems to occur? This report presents a summary of these problems. It was used to determine the areas in which the EERC can provide the most assistance through bench-scale and laboratory testing. The final objective of this project was to design and build a bench-scale high-temperature controlled atmosphere dynamic corrosion application furnace (CADCAF). The furnace will be used to evaluate refractory test samples in the presence of flowing corrodents for extended periods, to temperatures of 1600 C under controlled atmospheres. Corrodents will include molten slag, steel, and glass. This test should prove useful for the glass and steel industries when faced with the decision of choosing the best refractory for flowing corrodent conditions.

  3. Recent advances in refractories for steelmaking. Seikoyo taikabutsu no shinpo

    Energy Technology Data Exchange (ETDEWEB)

    Kasai, K. (Nippon Steel Corp., Tokyo (Japan))

    1994-05-07

    Advances and problems of refractories for steelmaking are explained. With the division of refining functions in the steel manufacturing process, and the development of new processes, functions which comply to them are being demanded for refractories. Progress related to the main refractories is summarized. Long-life refractories such as magnesite-carbon bricks, alumina-carbon silicate-carbon bricks, magnesite-chrome bricks were developed, and the unit requirement of furnace materials was reduced by 25% in 10 years. Labor-saving in furnace construction work also advanced by the development of the wall construction methods based on execution of casting process. For realization of high quality steel, ladles made of neutral alumina-spinel which does not contaminate the steel are used. For the preliminary treatment process of hot metal, ASC bricks and glass-added ASC bricks were developed as refractories, and the unit requirement was reduced. For converters, MgO-C bricks which have anticorrosion properties as well as antispalling properties are being broadly used. As for RH of secondary refining facility, magnesite-chrome type basic bricks which cope with the very severe conditions are used. For the ladle, alumina-spinel type casting material is used in order to save labor and to improve the quality of the steel. However, in the case of continuous casting, various types of refractories having special functions are used. 35 refs., 16 figs.

  4. Refractory Celiac Disease

    Directory of Open Access Journals (Sweden)

    K Khatami

    2014-04-01

    Full Text Available Refractory celiac disease (RCD is when malabsorption symptoms and villous atrophy persist despite strict adherence to a gluten free diet (GFD for more than 12 months and other causes of villous atrophy have been ruled out.  RCD is considered a rare disease and almost exclusively occurs in adults. Persistent diarrhea, abdominal pain, weight loss are the most common symptoms in RCD. Also, anemia, fatigue, malaise, thromboembolic events and coexisting autoimmune disorders are frequent. Diagnosis of RCD is based on other causes of unresponsiveness to the GFD, particularly collagenous sprue, ulcerative jejunitis, and enteropathy-associated T-cell lymphoma. Many disorders such as autoimmune enteropathy, tropical sprue, common variable immunodeficiency, and intolerance to non-gluten dietary proteins may have similar histological findings but not necessarily identical with CD and therefore should be excluded. Repeat intestinal biopsy may help to differentiate causes of non-responsive CD associated with ongoing villous atrophy (e.g., gluten contamination, small-bowel bacterial overgrowth, RCD. There are 2 subtypes of RCD according to absence (type I or presence (type II of an abnormal intraepithelial lymphocyte population. RCD type 1 usually becomes better with a combination of aggressive nutritional support, adherence to GFD, and pharmacologic therapies such as prednisone, budesonide and azathioprine. For RCD type 2, more aggressive therapeutic approach is needed since clinical response to therapies is less certain and may evolve into aggressive enteropathy associated T-cell lymphoma and the prognosis is poor.   Key words: Celiac Disease, Refractory.  

  5. Approaches to refractory epilepsy

    Directory of Open Access Journals (Sweden)

    Jerome Engel

    2014-01-01

    Full Text Available Epilepsy is one of the most common serious neurological conditions, and 30 to 40% of people with epilepsy have seizures that are not controlled by medication. Patients are considered to have refractory epilepsy if disabling seizures continue despite appropriate trials of two antiseizure drugs, either alone or in combination. At this point, patients should be referred to multidisciplinary epilepsy centers that perform specialized diagnostic testing to first determine whether they are, in fact, pharmacoresistant, and then, if so, offer alternative treatments. Apparent pharmacoresistance can result from a variety of situations, including noncompliance, seizures that are not epileptic, misdiagnosis of the seizure type or epilepsy syndrome, inappropriate use of medication, and lifestyle issues. For patients who are pharmacoresistant, surgical treatment offers the best opportunity for complete freedom from seizures. Surgically remediable epilepsy syndromes have been identified, but patients with more complicated epilepsy can also benefit from surgical treatment and require more specialized evaluation, including intracranial EEG monitoring. For patients who are not surgical candidates, or who are unwilling to consider surgery, a variety of other alternative treatments can be considered, including peripheral or central neurostimulation, ketogenic diet, and complementary and alternative approaches. When such alternative treatments are not appropriate or effective, quality of life can still be greatly improved by the psychological and social support services offered by multidisciplinary epilepsy centers. A major obstacle remains the fact that only a small proportion of patients with refractory epilepsy are referred for expert evaluation and treatment.

  6. [Lamotrigine in refractory epilepsy].

    Science.gov (United States)

    García-Escrivà, A; López-Hernández, N; Alvarez-Saúco, M; Pampliega-Pérez, A; Oliver-Navarrete, C; Asensio-Asensio, M; Moltó-Jordá, J M; Palao-Sánchez, A

    Lamotrigine (LTG) is a new antiepileptic drug indicated in all kinds of partial and generalised clonic-tonic seizures, both in monotherapy and polytherapy. Between 20 and 30% of epileptic patients have poor control over their seizures despite adequate treatment. We report on our experience regarding the long-term efficacy and tolerability of LTG in refractory seizures. We conducted a consecutive 10-year study of patients who began LTG therapy following poor control of their seizures, in spite of being treated with two or more antiepileptic drugs in monotherapy or in combination. Both their epidemiological and clinical data were collected for study. We studied the efficacy of the treatment, differentiating between remission (absence of seizures), improvement (reduction>50% of the seizures), inefficacy (reductionepilepsy, in 28.5% it was symptomatic and in the remaining 28.5% it was idiopathic. EEG readings and neuroimaging scans were pathological in 53.8% and 43.6%, respectively. After beginning therapy with LTG, 33% remained free of seizures, 43.6% improved, in 18.3% it was seen to be ineffective and 5.1% got worse. Dropout rate was 56.4%:23.1% due to insufficient control over the seizures, 17.9% owing to side effects and 15.4% because of non-compliance. Treatment with LTG offers a high degree of efficacy in the control of seizures in patients with refractory epilepsy, although it is limited by a high dropout rate.

  7. Platinum Group Coatings for Refractory Metals

    Science.gov (United States)

    1984-06-01

    molybdenum , tungsten, tantalum, niobium, rhenium or carbon/carbon must be used to fabricate the parts to withstand these temperatures. These materials and...layers (eg silicides, borides ) o Alloy coatings that form compact oxide layers (Ni and Co F based alloys) o Stable oxides that provide physical barriers...thermally etched) surface and seems to promote adhesion. Molybdenum rods 3mm in diameter were used as substrates during many of the runs where the

  8. REFRACTORY COATING FOR GRAPHITE MOLDS

    Science.gov (United States)

    Stoddard, S.D.

    1958-06-24

    Refractory coating for graphite molds used in the casting of uranium is described. The coating is an alumino-silicate refractory composition which may be used as a mold surface in solid form or as a coating applied to the graphite mold. The composition consists of a mixture of ball clay, kaolin, alumina cement, alumina, water, sodium silicate, and sodium carbonate.

  9. Wetting and Brazing of Alumina by Sn0.3Ag0.7Cu-Ti Alloy

    Science.gov (United States)

    Kang, J. R.; Song, X. G.; Hu, S. P.; Liu, D.; Guo, W. J.; Fu, W.; Cao, J.

    2017-12-01

    The wetting behavior of Sn0.3Ag0.7Cu (wt pct) with the addition of Ti on alumina was studied at 1273 K (1000 °C) using the sessile drop method. The wettability of Sn0.3Ag0.7Cu is significantly enhanced with the addition of Ti. Ti accumulates on the interface and reacts with O, producing TiO and yields good wetting. However, wetting is inhibited in high Ti containing droplets as intense Ti-Sn reactions take place. As a result of these competing reactions, the wettability of Sn0.3Ag0.7Cu-2Ti is the best, with the lowest equilibrium contact angle 24.6 deg. Thermodynamic calculations indicate that the value of the final contact angle cos θ varies linearly with Ti fraction in the Ti-Sn reaction-free case. The influence of the Ti-Sn reaction on wetting is quantitatively characterized by the deviation from the theoretical data. The adverse impact of Ti-Sn reaction on wetting increases in intensity with the droplets containing more Ti as the reaction between Ti and Sn becomes more intense and rapid. Alumina/alumina is brazed using different Ti containing Sn0.3Ag0.7Cu-Ti brazing metals at 1273 K (1000 °C) for 25 minutes. Pores are observed in joints prepared with Sn0.3Ag0.7Cu-0.7, 3, and 4Ti because of poor wettability. The highest joints shear strength of 28.6 MPa is obtained with Sn0.3Ag0.7Cu-2Ti.

  10. Monel Metal Castings

    Science.gov (United States)

    1935-07-17

    foot is adequate. A refractory , open sand should be used. Melting and Casting: The alloys are successfully produced from electro-nickel and copper...desirable if the charge is not chiefly Monel Metal scrap. About 0.1% magnesium should be ;ell stirred into the melt in the ladle before pouring. The addition...such as is used for the more refractory valve trim alloys. Carboloy tools probably can be used to advantage for the high silicon Monel Metal alloys

  11. Ciclosporin and refractory colitis.

    Science.gov (United States)

    Hawthorne, A Barney

    2003-03-01

    Intravenous ciclosporin 4 mg/kg daily is rapidly effective as a salvage therapy for patients with refractory colitis, who would otherwise face colectomy, but its use is controversial because of risk of toxicity, and long-term failure rate. Opportunistic infections remain a serious concern, with a number of reports of death related to ciclosporin. Renal and neurotoxicity are also well-recognized. The drug should not be continued for more than 3-6 months and its main role is as a bridge to azathioprine or 6-mercaptopurine. Risks of toxicity can be reduced by using lower doses (2 mg/kg/day intravenously), by oral microemulsion ciclosporin, or by monotherapy without corticosteroids. Preliminary evidence shows good response rates, but further studies are needed to confirm optimal use of this potent, but hazardous, therapy.

  12. Effects of two ergonomic improvements in brazing coils of air-handler units.

    Science.gov (United States)

    Loo, H S; Yeow, Paul H P

    2015-11-01

    The research aims to address the physically loading task and quality and productivity problems in the brazing of coils of air-handler units. Eight operators participated in two intervention studies conducted in a factory in Malaysia to compare the status quo brazing with (1) the use of a new twin-brazing torch that replaced the single-brazing gun and (2) brazing in a sitting position. The outcome measures are related to quality, productivity, monetary costs, body postures and symptoms. After baseline, Interventions I and II were applied for 3 months respectively. The results show a 58.9% quality improvement, 140% productivity increase and 113 times ROI. There was also a reduction in poor work postures e.g. in the raising of the arms and shoulders; bending, twisting and extending of the neck; and bending of left and right wrists, and the back. This research can be replicated in other factories that share similar processes. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  13. AA6082 to DX56-Steel Laser Brazing: Process Parameter-Intermetallic Formation Correlation

    Science.gov (United States)

    Narsimhachary, D.; Pal, S.; Shariff, S. M.; Padmanabham, G.; Basu, A.

    2017-09-01

    In the present study, laser-brazed AA6082 to DX56-galvanized steel joints were investigated to understand the influence of process parameters on joint strength in terms of intermetallic layer formation. 1.5-mm-thick sheet of aluminum alloy (AA6082-T6) and galvanized steel (DX56) sheet of 0.7 mm thickness were laser-brazed with 1.5-mm-diameter Al-12% Si solid filler wire. During laser brazing, laser power (4.6 kW) and wire feed rate (3.4 m/min) were kept constant with a varying laser scan speed of 3.5, 3, 2.5, 2, 1.5, and 1 m/min. Microstructure of brazed joint reveals epitaxial growth at the aluminum side and intermetallic layer formation at steel interface. Intermetallic layer formation was confirmed by EDS analysis and XRD study. Hardness profile showed hardness drop in filler region, and failure during tensile testing was initiated through the filler region near the steel interface. As per both experimental study and numerical analysis, it was observed that intermetallic layer thickness decreases with increasing brazing speed. Zn vaporization from galvanized steel interface also affected the joint strength. It was found that high laser scan speed or faster cooling rate can be chosen for suppressing intermetallic layer formation or at least decreasing the layer thickness which results in improved mechanical properties.

  14. An influence of a Glass Braze Composition on the Properties of Li-Ti Ferrite Joints

    Science.gov (United States)

    Lin, Panpan; Lin, Tiesong; He, Peng; Sekulic, Dusan P.; Zhao, Mengyuan; Wang, Shulei

    2017-04-01

    The influence of the chemical composition of Bi2O3-B2O3-SiO2-ZnO glass brazes on (i) the microstructure, (ii) the mechanical and (iii) the dielectric properties of Li-Ti ferrite joints was systematically investigated. The Bi5(Ti3Fe)O15 whisker and a white block phase consisting of Bi12SiO2 and Bi24B2O39 were observed in the joints of Li-Ti ferrite/Bi25-Ba and Li-Ti ferrite/glass brazes, respectively, containing a higher content of Bi2O3. No crystalline phase was detected in the Li-Ti ferrite/Bi25 and Li-Ti ferrite/Bi20 joints. The joint strength reached the maximum of 48 MPa in the Li-Ti ferrite/Bi25-Ba couples. It is assumed that this is mainly due to the strengthening effect of Bi5(Ti3Fe)O15 whiskers. The bonding temperature (700°C) had little effect on the dielectric properties of Li-Ti ferrite. Moreover, compared to the Bi25-Ba glass brazes, the Bi25 and Bi20 glass brazes had a less pronounced influence on the dielectric properties of joints. Different glass brazes can be tailored to different requirements depending on specific application and joint property requirements.

  15. Management of Refractory Vasodilatory Shock.

    Science.gov (United States)

    Jentzer, Jacob C; Vallabhajosyula, Saraschandra; Khanna, Ashish K; Chawla, Lakhmir S; Busse, Laurence W; Kashani, Kianoush B

    2018-01-09

    Refractory shock is a lethal manifestation of cardiovascular failure defined by an inadequate hemodynamic response to high doses of vasopressor medications. Approximately 7% of critically ill patients will develop refractory shock, with short-term mortality exceeding 50%. Refractory vasodilatory shock develops from uncontrolled vasodilation and vascular hyporesponsiveness to endogenous vasoconstrictors, causing failure of physiologic vasoregulatory mechanisms. Standard approaches to the initial management of shock include fluid resuscitation and initiation of norepinephrine. When these measures are inadequate to restore BP, vasopressin or epinephrine can be added. Few randomized studies exist to guide clinical management and hemodynamic stabilization in patients who do not respond to this standard approach. Adjunctive therapies, such as hydrocortisone, thiamine, and ascorbic acid, may increase BP in severe shock and should be considered when combination vasopressor therapy is needed. Novel vasopressor agents, such as synthetic human angiotensin II, can increase BP and reduce the need for high doses of catecholamine vasopressors in severe or refractory vasodilatory shock. Few effective rescue therapies exist for established refractory shock, which emphasizes the importance of aggressive intervention before refractory shock develops, including the earlier initiation of rational combination vasopressor therapy. The present review discusses the diagnosis and management of refractory shock to offer guidance for management of this important clinical problem and to provide a framework for future research. Copyright © 2018 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  16. Springback of aluminum alloy brazing sheet in warm forming

    Science.gov (United States)

    Han, Kyu Bin; George, Ryan; Kurukuri, Srihari; Worswick, Michael J.; Winkler, Sooky

    2017-10-01

    The use of aluminum is increasing in the automotive industry due to its high strength-to-weight ratio, recyclability and corrosion resistance. However, aluminum is prone to significant springback due to its low elastic modulus coupled with its high strength. In this paper, a warm forming process is studied to improve the springback characteristics of 0.2 mm thick brazing sheet with an AA3003 core and AA4045 clad. Warm forming decreases springback by lowering the flow stress. The parts formed have complex features and geometries that are representative of automotive heat exchangers. The key objective is to utilize warm forming to control the springback to improve the part flatness which enables the use of harder temper material with improved strength. The experiments are performed by using heated dies at several different temperatures up to 350 °C and the blanks are pre-heated in the dies. The measured springback showed a reduction in curvature and improved flatness after forming at higher temperatures, particularly for the harder temper material conditions.

  17. Investigation of Appropriate Refractory Material for Laboratory Electritic Resistrance Furnance

    Directory of Open Access Journals (Sweden)

    J.B Agboola

    2009-07-01

    Full Text Available There have been numerous efforts to increase the local content of furnaces; hence the choice of appropriate refractory material for lining of locally manufactured furnaces has remained a major concern. This research work investigates the choice of appropriate local refractory material for the lining of laboratory electric resistance furnace.Electric resistance furnaces are extensively used in the laboratory for heat treatment of metals and alloys. Refractory binders such as silicon carbide were experimented upon for strength and resistance to high temperature.The results obtained showed that Kankara fireclay containing 15% SiC ( 5.70 % linear shrinkage , 46.2% apparent porosity, 1.77gkm³ Bulk density, 18 cycles of spalling tests at 1300°C, 5.253KN/m² of cold strength has appropriate properties for producing grooved bricks for lining of laboratory electric resistance Furnace.

  18. Surface development of a brazing alloy during heat treatment–a comparison between UHV and APXPS

    Science.gov (United States)

    Rullik, L.; Johansson, N.; Bertram, F.; Evertsson, J.; Stenqvist, T.; Lundgren, E.

    2018-01-01

    In an attempt to bridge the pressure gap, APXPS was used to follow the surface development of an aluminum brazing sheet during heating in an ambient oxygen-pressure mimicking the environment of an industrial brazing furnace. The studied aluminum alloy brazing sheet is a composite material consisting of two aluminum alloy standards whose surface is covered with a native aluminum oxide film. To emphasize the necessity of studies of this system in ambient sample environments it is compared to measurements in UHV. Changes in thickness and composition of the surface oxide were followed after heating to 300 °C, 400 °C, and 500 °C. The two sets presented in this paper show that the surface development strongly depends on the environment the sample is heated in.

  19. Experimental and thermodynamic studies of beryllium replacement materials for CANDU brazed joints

    Energy Technology Data Exchange (ETDEWEB)

    Potter, K.N.; Ferrier, G.A.; Corcoran, E.C., E-mail: Kieran.Potter@rmc.ca [Royal Military College of Canada, Kingston, ON (Canada)

    2015-07-01

    Currently, appendages are joined to CANDU fuel elements via a brazing process, which uses beryllium as the filler material. A potential reduction in the occupational limit on airborne beryllium particulates has motivated research into alternative brazing materials. To this end, the Canadian nuclear industry has funded an initiative to identify and evaluate the suitability of several candidate materials. This work describes contributions toward the assessment of alternative brazing materials from the Royal Military College of Canada. Thermodynamic modelling was performed to predict the aqueous behaviour of each candidate material in CANDU coolant conditions characteristic of reactor shutdown, and experiments are underway to support modelling predictions. These results will assist in selecting a suitable replacement material for beryllium. (author)

  20. Surface development of a brazing alloy during heat treatment-a comparison between UHV and APXPS.

    Science.gov (United States)

    Rullik, L; Johansson, N; Bertram, F; Evertsson, J; Stenqvist, T; Lundgren, E

    2018-01-17

    In an attempt to bridge the pressure gap, APXPS was used to follow the surface development of an aluminum brazing sheet during heating in an ambient oxygen-pressure mimicking the environment of an industrial brazing furnace. The studied aluminum alloy brazing sheet is a composite material consisting of two aluminum alloy standards whose surface is covered with a native aluminum oxide film. To emphasize the necessity of studies of this system in ambient sample environments it is compared to measurements in UHV. Changes in thickness and composition of the surface oxide were followed after heating to 300 °C, 400 °C, and 500 °C. The two sets presented in this paper show that the surface development strongly depends on the environment the sample is heated in.

  1. Thermal Analysis of Brazing Seal and Sterilizing Technique to Break Contamination Chain for Mars Sample Return

    Science.gov (United States)

    Bao, Xiaoqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2015-01-01

    The potential to return Martian samples to Earth for extensive analysis is in great interest of the planetary science community. It is important to make sure the mission would securely contain any microbes that may possibly exist on Mars so that they would not be able to cause any adverse effects on Earth's environment. A brazing sealing and sterilizing technique has been proposed to break the Mars-to-Earth contamination chain. Thermal analysis of the brazing process was conducted for several conceptual designs that apply the technique. Control of the increase of the temperature of the Martian samples is a challenge. The temperature profiles of the Martian samples being sealed in the container were predicted by finite element thermal models. The results show that the sealing and sterilization process can be controlled such that the samples' temperature is maintained below the potentially required level, and that the brazing technique is a feasible approach to break the contamination chain.

  2. Nondestructive test of brazed cooling tubes of prototype bolometer camera housing using active infrared thermography.

    Science.gov (United States)

    Tahiliani, Kumudni; Pandya, Santosh P; Pandya, Shwetang; Jha, Ratneshwar; Govindarajan, J

    2011-01-01

    The active infrared thermography technique is used for assessing the brazing quality of an actively cooled bolometer camera housing developed for steady state superconducting tokamak. The housing is a circular pipe, which has circular tubes vacuum brazed on the periphery. A unique method was adopted to monitor the temperature distribution on the internal surface of the pipe. A stainless steel mirror was placed inside the pipe and the reflected IR radiations were viewed using an IR camera. The heat stimulus was given by passing hot water through the tubes and the temperature distribution was monitored during the transient phase. The thermographs showed a significant nonuniformity in the brazing with a contact area of around 51%. The thermography results were compared with the x-ray radiographs and a good match between the two was observed. Benefits of thermography over x-ray radiography testing are emphasized.

  3. Thermal analysis of brazing seal and sterilizing technique to break contamination chain for Mars sample return

    Science.gov (United States)

    Bao, Xiaoqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2015-03-01

    The potential to return Martian samples to Earth for extensive analysis is in great interest of the planetary science community. It is important to make sure the mission would securely contain any microbes that may possibly exist on Mars so that they would not be able to cause any adverse effects on Earth's environment. A brazing sealing and sterilizing technique has been proposed to break the Mars-to-Earth contamination chain. Thermal analysis of the brazing process was conducted for several conceptual designs that apply the technique. Control of the increase of the temperature of the Martian samples is a challenge. The temperature profiles of the Martian samples being sealed in the container were predicted by finite element thermal models. The results show that the sealing and sterilization process can be controlled such that the samples' temperature is maintained below the potentially required level, and that the brazing technique is a feasible approach to break the contamination chain.

  4. Intrathecal ziconotide for refractory pain.

    Science.gov (United States)

    Doggrell, Sheila A

    2004-07-01

    For cancer and AIDS patients, 10-30% of pain is refractory to strong opioids, requiring intraspinal administration for pain management. Ziconotide is a selective N-type calcium channel blocker, which inhibits neurotransmitter release, and following intrathecal administration will affect primary nociceptive afferents. In 108 patients with previously unmanaged refractory pain despite the use of systemic or intrathecal opioids, in the initial titration phase, the mean Visual Analogue Scale of Pain Intensity scores improved more in the ziconotide group (53%) than the placebo group (18%). Serious adverse effects were more common in the ziconotide group (31%) than placebo group (10%) in the initial titration phase. In the 48 patients receiving ziconotide, who proceeded to the maintenance phase, the benefit of ziconotide was continued. Until a new approach with a better effectiveness/adverse effects profile than ziconotide for refractory pain emerges, further optimisation of ziconotide for use in the treatment of refractory pain should be undertaken.

  5. Vacuum brazing of TiAl48Cr2Nb2 casting alloys based on TiAl (γ intermetallic compound

    Directory of Open Access Journals (Sweden)

    Z. Mirski

    2010-01-01

    Full Text Available A growing interest in modern engineering materials characterised by increasingly better operational parameters combined with a necessity to obtain joints of such materials representing good operation properties create important research and technological problems of today. These issues include also titanium joints or joints of titanium alloys based on intermetallic compounds. Brazing is one of the basic and sometimes even the only available welding method used for joining the aforesaid materials in production of various systems, heat exchangers and, in case of titanium alloys based on intermetallic compounds, turbine elements and space shuttle plating etc. This article presents the basic physical and chemical properties as well as the brazability of alloys based on intermetallic compounds. The work also describes the principle and mechanisms of diffusion-brazed joint formation as well as reveals the results of metallographic and strength tests involving diffusion-welded joints of TiAl48Cr3Nb2 casting alloy based on TiAl (γ phase with the use of sandwich-type layers of silver-based parent metal (grade B- Ag72Cu-780 (AG 401 and copper (grade CF032A. Structural examination was performed by means of light microscopy, scanning electron microscope (SEM and energy dispersion spectrometer (EDS. Furthermore, the article reveals the results of shear strength tests involving the aforementioned joints.

  6. Influence of laser power on microstructure and mechanical properties of laser welded-brazed Mg to Ni coated Ti alloys

    Science.gov (United States)

    Tan, Caiwang; Lu, Qingshuang; Chen, Bo; Song, Xiaoguo; Li, Liqun; Feng, Jicai; Wang, Yang

    2017-03-01

    AZ31B Magnesium (Mg) and Ti-6Al-4V titanium (Ti) alloys with Ni coating were joined by laser welding-brazing process using AZ92 Mg based filler. The influence of laser power on microstructure and mechanical properties were investigated. Ni coating was found to significantly promote good wetting-spreading ability of molten filler on the Ti sheet. Acceptable joints without obvious defects were obtained within a relatively wide processing window. In the process metallurgical bonding was achieved by the formation of Ti3Al phase at direct irradiation zone and Al-Ni phase followed by a layer of Mg-Al-Ni ternary compound adjacent to the fusion zone at the intermediate zone. The thickness of reaction layers increased slowly with the increasing laser power. The tensile-shear test indicated that joints produced at the laser power of 1300 W reached 2387 N fracture load, representing 88.5% joint efficiency with respect to the Mg base metal. The corresponding failure occurred in the fusion zone of the Mg base metal, while joints fractured at the interface at lower/higher laser power due to the crack or excessive intermetallic compound (IMC) formation along the interface.

  7. Bulk Vitrification Castable Refractory Block Protection Study

    Energy Technology Data Exchange (ETDEWEB)

    Hrma, Pavel R.; Bagaasen, Larry M.; Beck, Andrew E.; Brouns, Thomas M.; Caldwell, Dustin D.; Elliott, Michael L.; Matyas, Josef; Minister, Kevin BC; Schweiger, Michael J.; Strachan, Denis M.; Tinsley, Bronnie P.; Hollenberg, Glenn W.

    2005-05-01

    Bulk vitrification (BV) was selected for a pilot-scale test and demonstration facility for supplemental treatment to accelerate the cleanup of low-activity waste (LAW) at the Hanford U.S. DOE Site. During engineering-scale (ES) tests, a small fraction of radioactive Tc (and Re, its nonradioactive surrogate) were transferred out of the LAW glass feed and molten LAW glass, and deposited on the surface and within the pores of the castable refractory block (CRB). Laboratory experiments were undertaken to understand the mechanisms of the transport Tc/Re into the CRB during vitrification and to evaluate various means of CRB protection against the deposition of leachable Tc/Re. The tests used Re as a chemical surrogate for Tc. The tests with the baseline CRB showed that the molten LAW penetrates into CRB pores before it converts to glass, leaving deposits of sulfates and chlorides when the nitrate components decompose. Na2O from the LAW reacts with the CRB to create a durable glass phase that may contain Tc/Re. Limited data from a single CRB sample taken from an ES experiment indicate that, while a fraction of Tc/Re is present in the CRB in a readily leachable form, most of the Tc/Re deposited in the refractory is retained in the form of a durable glass phase. In addition, the molten salts from the LAW, mainly sulfates, chlorides, and nitrates, begin to evaporate from BV feeds at temperatures below 800 C and condense on solid surfaces at temperatures below 530 C. Three approaches aimed at reducing or preventing the deposition of soluble Tc/Re within the CRB were proposed: metal lining, sealing the CRB surface with a glaze, and lining the CRB with ceramic tiles. Metal liners were deemed unsuitable because evaluations showed that they can cause unacceptable distortions of the electric field in the BV system. Sodium silicate and a low-alkali borosilicate glaze were selected for testing. The glazes slowed down molten salt condensate penetration, but did little to reduce the

  8. Impact of alternate fuels on industrial refractories and refractory insulation applications. An Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Wei, G.C.; Tennery, V.J.

    1976-09-01

    The effects of use of alternate fuels such as distillate oils, residual oils, coal, producer gas, and electricity on refractory insulation are evaluated. Sections are included on alternate fuels for 1976 to 1980, assessment by industry of fuel conversion impact on industrial refractories in the period 1976 to 1980, interactions of alternate fuel combustion products with refractories and refractory insulation, and analysis of degradation mechanisms in refractories and refractory materials. (JRD)

  9. Benefit of wider gap at brazing aluminium alloys to stainless steels in the air using the flux containing zinc

    Energy Technology Data Exchange (ETDEWEB)

    Ikeshoji, T.T.; Liu, S.; Suzumura, A.; Yamazaki, T. [Tokyo Institute of Technology (Japan)

    2007-07-01

    The brazing of aluminum alloys to stainless steel was conducted using the aluminum-silicon brazing filler in the air under the existence of the flux. Aluminum alloys and stainless steel easily form the strong oxide layers on the surface and they are the obstacle to accomplish their dissimilar brazing joint in the air. To remove those oxide layers, the water soluble active corrosion chloride flux including zinc chloride was pasted. In this experiment, Zn simultaneously diffused fast in the aluminum bulk. The EDX mapping showed the diffusion of Zn into Al alloys, on the other hand silicon was condensed in the residual molten brazing filler. The fast isothermal solidification from the Al alloys surface before the breakage of the oxide film on the stainless surface is considered the obstacle of brazing them in the air. The wetting time of the stainless steel surface using the flux with zinc and the aluminum-silicon brazing filler was measured. The numerical simulations on the Fickian diffusion of the Si into aluminum alloys is also conducted to estimate the isothermal solidification time from the Al alloys' surface. Combining the results of the wetting time and the isothermal solidification simulations, the gap width required for accomplishment of the brazing Al alloys and stainless steel was proposed. (orig.)

  10. Welding, Cutting and Brazing Safety. Module SH-28. Safety and Health.

    Science.gov (United States)

    Center for Occupational Research and Development, Inc., Waco, TX.

    This student module on welding, cutting and brazing safety is one of 50 modules concerned with job safety and health. This module addresses safety precautions for oxyacetylene welding and gives information about handling compressed gases. Following the introduction, 17 objectives (each keyed to a page in the text) the student is expected to…

  11. 49 CFR 178.50 - Specification 4B welded or brazed steel cylinders.

    Science.gov (United States)

    2010-10-01

    ... cylinders over 18 inches long must be protected by footrings. Welding procedures and operators must be... may be used with proper welding procedure. (f) Wall thickness. The wall thickness of the cylinder must... 49 Transportation 2 2010-10-01 2010-10-01 false Specification 4B welded or brazed steel cylinders...

  12. Training Materials Sourcebook. Welding, Brazing, and Flame-Cutting. Voc./Tec. Resources Series Number 2.

    Science.gov (United States)

    Canadian Commission of Employment and Immigration, Ottawa (Ontario).

    Second in a resource series (see note), this annotated bibliography provides detailed information on training curriculum and instructional materials for welding, brazing, and flame-cutting. The materials are divided into thirty-fie sections by topic and type. Specific topic areas include gas and arc welding; arc welding; oxyacetylene welding and…

  13. CHOOSING THE BEST BRAZING TECHNOLOGY FOR ALUMINUM ALLOYS USING THE ELECTRE METHOD

    Directory of Open Access Journals (Sweden)

    Andrei DIMITRESCU

    2015-05-01

    Full Text Available This paper presents several methods of rationalizing group decisions under uncertainty. There are showed research and results from the use of multi-criteria decision optimization methods for the particular case of performing the brazing joints of aluminum alloy parts directly applicable in aeronautic industry.

  14. Effect of braze processing on the microstructure and mechanical properties of SCS-6/beta21S titanium matrix composites

    Science.gov (United States)

    Hoffman, Eric K.; Bird, R. K.; Dicus, Dennis L.

    1992-01-01

    An investigation is conducted of the effects of braze processing on the microstructure and tensile properties of SiC fiber-reinforced Ti-15Mo-2.7Nb-3Al-0.25Si-matrix composite (TMC) laminates; the brazing alloy was the commercial Ti-15Cu-15Ni, in both its conventional and metglass forms. Tensile tests conducted at room temperature, 1200 F, and 1500 F showed that the braze processes (1) had little effect on tensile properties, and (2) appeared to degrade neither the reinforcing fibers not the fiber/matrix interfacial bondline.

  15. Testing Requirements for Refractory Materials

    Science.gov (United States)

    Calle, Luz Marina; Hintze, Paul E.; Parlier, Christopher R.; Curran, Jerome P.; Kolody, Mark R.; Sampson, Jeffrey W,; Montgomery, Eliza M.

    2012-01-01

    Launch Pads 39A and 39B currently use refractory material (Fondu Fyre) in the flame trenches. This material was initially approved for the Saturn program. This material had a lifetime of 10years according to the manufacturer, and it has been used for over 40 years. As a consequence, the Fondu Fyre at Launch Complex 39 requires repair subsequent to almost every launch. A review of the literature indicates that the gunned Fondu Fyre refractory product (WA-1 G) was never tested prior to use. With the recent severe damage to the flame trenches, a new refractory material is sought to replace Fondu Fyre. In order to replace Fondu Fyre, a methodology to test and evaluate refractory products was developed. This paper outlines this methodology and discusses current testing requirements, as well as the laboratory testing that might be required. Furthermore, this report points out the necessity for subscale testing, the locations where this testing can be performed, and the parameters that will be necessary to qualify a product. The goal is to identify a more durable refractory material that has physical, chemical, and thermal properties suitable to withstand the harsh environment of the launch pads at KSC.

  16. Bulk Vitrification Performance Enhancement: Refractory Lining Protection Against Molten Salt Penetration

    Energy Technology Data Exchange (ETDEWEB)

    Hrma, Pavel R.; Bagaasen, Larry M.; Schweiger, Michael J.; Evans, Michael B.; Smith, Benjamin T.; Arrigoni, Benjamin M.; Kim, Dong-Sang; Rodriguez, Carmen P.; Yokuda, Satoru T.; Matyas, Josef; Buchmiller, William C.; Gallegos, Autumn B.; Fluegel, Alexander

    2007-08-06

    Bulk vitrification (BV) is a process that heats a feed material that consists of glass-forming solids and dried low-activity waste (LAW) in a disposable refractory-lined metal box using electrical power supplied through carbon electrodes. The feed is heated to the point that the LAW decomposes and combines with the solids to generate a vitreous waste form. This study supports the BV design and operations by exploring various methods aimed at reducing the quantities of soluble Tc in the castable refractory block portion of the refractory lining, which limits the effectiveness of the final waste form.

  17. Hermetic diamond capsules for biomedical implants enabled by gold active braze alloys.

    Science.gov (United States)

    Lichter, Samantha G; Escudié, Mathilde C; Stacey, Alastair D; Ganesan, Kumaravelu; Fox, Kate; Ahnood, Arman; Apollo, Nicholas V; Kua, Dunstan C; Lee, Aaron Z; McGowan, Ceara; Saunders, Alexia L; Burns, Owen; Nayagam, David A X; Williams, Richard A; Garrett, David J; Meffin, Hamish; Prawer, Steven

    2015-01-01

    As the field of biomedical implants matures the functionality of implants is rapidly increasing. In the field of neural prostheses this is particularly apparent as researchers strive to build devices that interact with highly complex neural systems such as vision, hearing, touch and movement. A retinal implant, for example, is a highly complex device and the surgery, training and rehabilitation requirements involved in deploying such devices are extensive. Ideally, such devices will be implanted only once and will continue to function effectively for the lifetime of the patient. The first and most pivotal factor that determines device longevity is the encapsulation that separates the sensitive electronics of the device from the biological environment. This paper describes the realisation of a free standing device encapsulation made from diamond, the most impervious, long lasting and biochemically inert material known. A process of laser micro-machining and brazing is described detailing the fabrication of hermetic electrical feedthroughs and laser weldable seams using a 96.4% gold active braze alloy, another material renowned for biochemical longevity. Accelerated ageing of the braze alloy, feedthroughs and hermetic capsules yielded no evidence of corrosion and no loss of hermeticity. Samples of the gold braze implanted for 15 weeks, in vivo, caused minimal histopathological reaction and results were comparable to those obtained from medical grade silicone controls. The work described represents a first account of a free standing, fully functional hermetic diamond encapsulation for biomedical implants, enabled by gold active alloy brazing and laser micro-machining. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Infliximab for refractory oral ulcers.

    Science.gov (United States)

    Ryu, Hee Jung; Seo, Mi Ryoung; Choi, Hyo Jin; Baek, Han Joo

    2014-01-01

    Recurrent oral ulcer (ROU) is a common condition that significantly impacts quality of life. It is often related to systemic diseases, such as Behçet's disease (BD), Crohn's disease, and ulcerative colitis. Treatment of ROU depends on its severity: from topical agents for mild cases to systemic agents, such as corticosteroids, azathioprine, or other immunosuppressants for severe cases. Recently, good results have been reported with infliximab in refractory ROU. However, the optimal dosage and treatment duration have not been determined and the cost and potential side effects should be considered. We report on four patients who received a single-dose infliximab for refractory ROU. Two patients had refractory ROU with no underlying disease; one of them had soft palate perforation accompanied by severe oral ulcers. The two other patients had ROU of BD without major organ involvement. All patients received a single infusion of infliximab and an additional infusion was given on demand in one patient. Infliximab showed a rapid, good response in three patients and was also effective in improving the acute inflammation in the perforation of the soft palate, which had been resistant to conventional therapies. These effects diminished over a few weeks, but the ROU were tolerable and it was not necessary to increase steroids or add another medicine for about 1 year. We suggest that a single infusion of infliximab can be considered for refractory ROU. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Dexmedetomidine for Refractory Intracranial Hypertension.

    Science.gov (United States)

    Schomer, Kendra J; Sebat, Christian M; Adams, Jason Y; Duby, Jeremiah J; Shahlaie, Kiarash; Louie, Erin L

    2017-01-01

    Dexmedetomidine (DEX) is a selective α2 adrenergic agonist that is commonly used for sedation in the intensive care unit (ICU). The role of DEX for adjunctive treatment of refractory intracranial hypertension is poorly defined. The primary objective of this study was to determine the effect of DEX on the need for rescue therapy (ie, hyperosmolar boluses, extraventricular drain [EVD] drainages) for refractory intracranial hypertension. Secondary objectives included the number of intracranial pressure (ICP) excursions, bradycardic, hypotensive, and compromised cerebral perfusion pressure episodes. This retrospective cohort study evaluated patients admitted to the neurosurgical ICU from August 1, 2009, to July 29, 2015, and who received DEX for refractory intracranial hypertension. The objectives were compared between the 2 time periods-before (pre-DEX) and during therapy (DEX). Twenty-three patients with 26 episodes of refractory intracranial hypertension met the inclusion criteria. The number of hyperosmolar boluses was decreased after DEX therapy was initiated. Mannitol boluses required were statistically reduced (1 vs 0.5, P = .03); however, reduction in hypertonic boluses was not statistically significant (1.3 vs 0.9, P = .2). The mean number of EVD drainages per 24 hours was not significantly different between the time periods (15.7 vs 14.0, P = .35). The rate of ICP excursions did not differ between the 2 groups (24.3 vs 22.5, P = .62). When compared to pre-DEX data, there was no difference in the median number of hypotensive (0 vs 0), bradycardic (0 vs 0), or compromised cerebral perfusion pressure episodes (0.5 vs 1.0). Dexmedetomidine may avoid increases in the need for rescue therapy when used as an adjunctive treatment of refractory intracranial hypertension without compromising hemodynamics.

  20. Mechanical properties of refractory concretes for boilers; Propriedades mecanicas de concretos refratarios para caldeiras

    Energy Technology Data Exchange (ETDEWEB)

    Angioletto, E.; Pelisser, F.; Peterson, M.; Angioletto, E.; Rocha, M.R.; Arnt, A.B.C. [Universidade do Estado de Santa Catarina (UDESC), Criciuma, SC (Brazil)], E-mail: ean@unesc.net; Coelho, R. [Tractebel Energia, Florianpolis, SC (Brazil)

    2010-07-01

    Refractory concretes are used in extremely physically demanding conditions. An important example is concretes used as sealing systems in boilers, where their dimensional stability at high temperatures is fundamental to durability and has a strong impact on maintenance costs and system idleness. In this work, refractory concretes with different compositions were characterized and then tested by dilatometry, for compressive strength and in assays involving adherence between tensile concrete/metal inserts, simulating the fixing system in boilers. Analysis of the results showed that refractory concretes do not present retraction due to air during drying, eliminating the possibility of cracking. While casting the plate/prototype with metal inserts, satisfactory concrete/metal adherence was verified and surface cracking occurred that did not influence the tensile bond strength between the insert and the concrete. (author)

  1. Microstructure Evolution During Stainless Steel-Copper Vacuum Brazing with a Ag/Cu/Pd Filler Alloy: Effect of Nickel Plating

    Science.gov (United States)

    Choudhary, R. K.; Laik, A.; Mishra, P.

    2017-03-01

    Vacuum brazing of stainless steel and copper plates was done using a silver-based filler alloy. In one set of experiments, around 30-µm-thick nickel coatings were electrochemically applied on stainless steel plates before carrying out the brazing runs and its effect in making changes in the braze-zone microstructure was studied. For brazing temperature of 830 °C, scanning electron microscopy examination of the braze-zone revealed that relatively sound joints were obtained when brazing was done with nickel-coated stainless steel than with uncoated one. However, when brazing of nickel-coated stainless steel and copper plates was done at 860 °C, a wide crack appeared in the braze-zone adjacent to copper side. Energy-dispersive x-ray analysis and electron microprobe analysis confirmed that at higher temperature, the diffusion of Cu atoms from copper plate towards the braze-zone was faster than that of Ni atoms from nickel coating. Helium leak rate of the order 10-11 Pa m3/s was obtained for the crack-free joint, whereas this value was higher than 10-4 Pa m3/s for the joint having crack. The shear strength of the joint was found to decrease considerably due to the presence of crack.

  2. Typical corrosion of alumina refractory in aluminum reflow oven; Corrosao tipica de refratarios aluminosos em forno de refusao de aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Baldo, Jaoa B., E-mail: baldo@ufscar.br [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil)

    2014-07-01

    The refractory linings of furnaces for secondary melting of aluminum, are exposed to intense attack by the molten metal. This occurs, because molten aluminum has a strong reducing power over the refractory oxide components, particularly Fe{sub 2}O{sub 3}, SiO{sub 2} and TiO{sub 2}. In this work, based on X-ray diffraction and scanning electron microscopy, it is presented a post mortem study of the mechanisms that lead to a premature wear of a 80% Al2O3 chemically bonded refractory bricks, used in the metal line of an aluminum re-melting furnace. The SEM analysis demonstrated that the oxides SiO{sub 2} and TiO{sub 2} contained in the refractory were reduced and transformed into their metallic elements causing an intense structural spalling. (author)

  3. Enhancement of the life of refractories through the operational experience of plasma torch melter

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Young Pyo [Technology Institute, Korea Radioactive waste Agency (KORAD), Daejeon (Korea, Republic of); Choi, Jaang Young [Chungnam National University, Daejeon (Korea, Republic of)

    2016-06-15

    The properties of wastes for melting need to be considered to minimize the maintenance of refractory and to discharge the molten slags smoothly from a plasma torch melter. When the nonflammable wastes from nuclear facilities such as concrete debris, glass, sand, etc., are melted, they become acid slags with low basicity since the chemical composition has much more acid oxides than basic oxides. A molten slag does not have good characteristics of discharge and is mainly responsible for the refractory erosion due to its low liquidity. In case of a stationary plasma torch melter with a slant tapping port on the wall, a fixed amount of molten slags remains inside of tapping hole as well as the melter inside after tapping out. Nonmetallic slags keep the temperature higher than melting point of metal because metallic slags located on the bottom of melter by specific gravity difference are simultaneously melted when dual mode plasma torch operates in transferred mode. In order to minimize the refractory erosion, the compatible refractories are selected considering the temperature inside the melter and the melting behavior of slags whether to contact or noncontact with molten slags. An acidic refractory shall not be installed in adjacent to a basic refractory for the resistibility against corrosion.

  4. High heat flux test of tungsten brazed mock-ups developed for KSTAR divertor

    Energy Technology Data Exchange (ETDEWEB)

    Song, J.H. [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, K.M., E-mail: kyungmin@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Hong, S.H.; Kim, H.T.; Park, S.H.; Park, H.K.; Ahn, H.J. [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, S.K.; Lee, D.W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-11-01

    The tungsten (W) brazed flat type mock-up which consists of W, OFHC-Cu (oxygen-free high conductive copper) and CuCrZr alloy has been designed for KSTAR divertor in preparation for KSTAR upgrade with 17 MW heating power. For verification of the W brazed mock-up, the high heat flux test is performed at KoHLT-EB (Korea High Heat Load Test Facility-Electron Beam) in KAERI (Korea Atomic Energy Research Institute). Three mock-ups are tested for several thousand thermal cycles with absorbed heat flux up to 5 MW/m{sup 2} for 20 s duration. There is no evidence of the failure at the bonding joints of all mock-ups after HHF test. Finite element analysis (FEA) is performed to interpret the result of the test. As a result, it is considered that the local area in the water is in the subcooled boiling regime.

  5. Effect of dual laser beam on dissimilar welding-brazing of aluminum to galvanized steel

    Science.gov (United States)

    Mohammadpour, Masoud; Yazdian, Nima; Yang, Guang; Wang, Hui-Ping; Carlson, Blair; Kovacevic, Radovan

    2018-01-01

    In this investigation, the joining of two types of galvanized steel and Al6022 aluminum alloy in a coach peel configuration was carried out using a laser welding-brazing process in dual-beam mode. The feasibility of this method to obtain a sound and uniform brazed bead with high surface quality at a high welding speed was investigated by employing AlSi12 as a consumable material. The effects of alloying elements on the thickness of intermetallic compound (IMC) produced at the interface of steel and aluminum, surface roughness, edge straightness and the tensile strength of the resultant joint were studied. The comprehensive study was conducted on the microstructure of joints by means of a scanning electron microscopy and EDS. Results showed that a dual-beam laser shape and high scanning speed could control the thickness of IMC as thin as 3 μm and alter the failure location from the steel-brazed interface toward the Al-brazed interface. The numerical simulation of thermal regime was conducted by the Finite Element Method (FEM), and simulation results were validated through comparative experimental data. FEM thermal modeling evidenced that the peak temperatures at the Al-steel interface were around the critical temperature range of 700-900 °C that is required for the highest growth rate of IMC. However, the time duration that the molten pool was placed inside this temperature range was less than 1 s, and this duration was too short for diffusion-control based IMC growth.

  6. Synchronous separation, seaming, sealing and sterilization (S4) using brazing for sample containerization and planetary protection

    Science.gov (United States)

    Bar-Cohen, Yoseph; Badescu, Mircea; Bao, Xiaoqi; Lee, Hyeong Jae; Sherrit, Stewart; Freeman, David; Campos, Sergio

    2017-04-01

    The potential return of samples back to Earth in a future NASA mission would require protection of our planet from the risk of bringing uncontrolled biological materials back with the samples. In order to ensure this does not happen, it would be necessary to "break the chain of contact (BTC)", where any material reaching Earth would have to be inside a container that is sealed with extremely high confidence. Therefore, it would be necessary to contain the acquired samples and destroy any potential biological materials that may contaminate the external surface of their container while protecting the sample itself for further analysis. A novel synchronous separation, seaming, sealing and sterilization (S4) process for sample containerization and planetary protection has been conceived and demonstrated. A prototype double wall container with inner and outer shells and Earth clean interstitial space was used for this demonstration. In a potential future mission, the double wall container would be split into two halves and prepared on Earth, while the potential on-orbit execution would consist of inserting the sample into one of the halves and then mating to the other half and brazing. The use of brazing material that melts at temperatures higher than 500°C would assure sterilization of the exposed areas since all carbon bonds are broken at this temperature. The process would be executed in two-steps, Step-1: the double wall container halves would be fabricated and brazed on Earth; and Step-2: the containerization and sterilization process would be executed on-orbit. To prevent potential jamming during the process of mating the two halves of the double wall container and the extraction of the brazed inner container, a cone-within-cone approach has been conceived and demonstrated. The results of this study will be described and discussed.

  7. Experimental results for hydrocarbon refrigerant vaporization in brazed plate heat exchangers at high pressure

    OpenAIRE

    Desideri, Adriano; Rhyl Kaern, Martin; Ommen Schmidt, Torben; Wronski, Jorrit; Quoilin, Sylvain; Lemort, Vincent; Haglind, Fredrik

    2016-01-01

    In recent years the interest in small capacity organic Rankine cycle (ORC) power systems for harvesting low quality waste thermal energy from industrial processes has been steadily growing. Micro ORC systems are normally equipped with brazed plate heat exchangers which allows for efficient heat transfer with a compact design. An accurate prediction of the heat transfer process characterizing these devices is required from the design phase to the development of model- based control strategies....

  8. Corrosion Investigation of Laser Brazed Aluminium-Steel Joints Using the Scanning Kelvin Probe

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo-Martinez, C.A.; Vrenken, J.; Hannour, F. [Corus Research, Development and Technology, IJmuiden (Netherlands)

    2004-07-01

    Full text of publication follows: Given the increased interest of the automotive and transport industry in using aluminium-steel combinations to produce lighter vehicles, with reduced pollutant emissions, joining technologies such as laser brazing appear promising. However, in this type of joint, aluminium and steel become in electrical contact, increasing the susceptibility to galvanic corrosion. This depends on the electrochemical properties of the alloys to be joined and the joint itself. Differences in microstructure and composition resulting from such joint configurations during the brazing process also influence significantly the corrosion properties of the joint. In this paper, the corrosion behaviour of AA6016/ steel joints was studied using scanning Kelvin probe on bare, zinc phosphated and electro-coated specimens. In addition, for comparison, panels were subjected to accelerated cyclic corrosion tests, including the Hoogovens cyclic test (HCT) and the VDA 621-415. Kelvin probe potential mapping showed that corrosion and coating delamination initiate locally at the interface galvanized steel/joint. However, relative long exposures were required during accelerated testing (i.e. 10 weeks VDA) to achieve detectable corrosion and coating delamination at the joint. This indicates that the galvanic coupling effect is only moderate and it can be controlled with an appropriate coating system. In conclusion, AA6016/galvanized steel laser-brazed joints certainly appear to be applicable for car bodies (i.e. roof type applications). (authors)

  9. Heating and thermal control of brazing technique to break contamination path for potential Mars sample return

    Science.gov (United States)

    Bao, Xiaoqi; Badescu, Mircea; Sherrit, Stewart; Bar-Cohen, Yoseph; Campos, Sergio

    2017-04-01

    The potential return of Mars sample material is of great interest to the planetary science community, as it would enable extensive analysis of samples with highly sensitive laboratory instruments. It is important to make sure such a mission concept would not bring any living microbes, which may possibly exist on Mars, back to Earth's environment. In order to ensure the isolation of Mars microbes from Earth's Atmosphere, a brazing sealing and sterilizing technique was proposed to break the Mars-to-Earth contamination path. Effectively, heating the brazing zone in high vacuum space and controlling the sample temperature for integrity are key challenges to the implementation of this technique. The break-thechain procedures for container configurations, which are being considered, were simulated by multi-physics finite element models. Different heating methods including induction and resistive/radiation were evaluated. The temperature profiles of Martian samples in a proposed container structure were predicted. The results show that the sealing and sterilizing process can be controlled such that the samples temperature is maintained below the level that may cause damage, and that the brazing technique is a feasible approach to breaking the contamination path.

  10. Investigation of tungsten/steel brazing using Ta and Cu interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wensheng; Wang, Zixuan; Ma, Yunzhu, E-mail: zhuzipm@csu.edu.cn; Cai, Qingshan

    2016-12-15

    The brazing processes, using Ta and Cu interlayer respectively, were carried out to study the joining of W and steel with Ni–based amorphous foil filler. The W/Ta/steel and W/Cu/steel joints were conducted in vacuum at 1050 °C for 1 h. The interfacial microstructure and mechanical properties of joints were investigated by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and tensile strength measurement. The results show that a reliable bonding between W and steel could be obtained by using both Ta and Cu interlayer. The fracture sources of W/steel brazing joints were predominantly in the tungsten substrate near the brazing seam, which agrees reasonable well with the calculation result of finite element method (FEM). The average tensile strength of W/Ta/steel and W/Cu/steel joints were 257.8 MPa and 276.7 MPa respectively. Comparing with hard interlayer Ta, soft interlayer Cu could reduce residual tress in W substrate and improve the mechanical property more effectively.

  11. Mechanical Design, Brazing and Assembly Procedures of the LINAC4 RFQ

    CERN Document Server

    Mathot, S; Briswalter, A; Callamand, Th; Carosone, J; Favre, N; Geisser, J M; Lombardi, A; Maire, V; Malabaila, M; Pugnat, D; Richerot, Ph; Riffaut, B; Rossi, C; Timmins, M; Vacca, A; Vandoni, G; Vretenar, M

    2010-01-01

    The Linac4 RFQ will accelerate the H- beam from the ion source to the energy of 3 MeV. The RFQ is composed of three sections of one meter each, assembled by means of ultra high vacuum flanges and adjustable centring rings. The complete 3-m long RFQ will be supported isostatically over 3 points like a simple beam in order to minimise the maximum deflection. The ridge line, used to feed the RF power into the RFQ, will be supported via springs and its position adjusted in such way that no strain is introduced into the RFQ at the moment of its connection. The mechanical design has been done at CERN where the modules are completely manufactured, heat treated and brazed also. In that way, all of the processes are carefully controlled and the influence, notably of the heat treatments, has been understood in a better way. Since 2002 several four vanes RFQ modules have been brazed at CERN for the TRASCO and IPHI projects. A two-step brazing procedure has been tested. This technique is actually used for the assembly of...

  12. A Study of Deposition Coatings Formed by Electroformed Metallic Materials.

    Directory of Open Access Journals (Sweden)

    Shoji Hayashi

    Full Text Available Major joining methods of dental casting metal include brazing and laser welding. However, brazing cannot be applied for electroformed metals since heat treatment could affect the fit, and, therefore, laser welding is used for such metals. New methods of joining metals that do not impair the characteristics of electroformed metals should be developed. When new coating is performed on the surface of the base metal, surface treatment is usually performed before re-coating. The effect of surface treatment is clinically evaluated by peeling and flex tests. However, these testing methods are not ideal for deposition coating strength measurement of electroformed metals. There have been no studies on the deposition coating strength and methods to test electroformed metals. We developed a new deposition coating strength test for electroformed metals. The influence of the negative electrolytic method, which is one of the electrochemical surface treatments, on the strength of the deposition coating of electroformed metals was investigated, and the following conclusions were drawn: 1. This process makes it possible to remove residual deposits on the electrodeposited metal surface layer. 2. Cathode electrolysis is a simple and safe method that is capable of improving the surface treatment by adjustments to the current supply method and current intensity. 3. Electrochemical treatment can improve the deposition coating strength compared to the physical or chemical treatment methods. 4. Electro-deposition coating is an innovative technique for the deposition coating of electroformed metal.

  13. Detached Melt Nucleation during Diffusion Brazing of a Technical Ni-based Superalloy: A Phase-Field Study

    Science.gov (United States)

    Böttger, B.; Apel, M.; Laux, B.; Piegert, S.

    2015-06-01

    Advanced solidification processes like welding, soldering, and brazing are often characterized by their specific solidification conditions. But they also may include different types of melting processes which themselves are strongly influenced by the initial microstructures and compositions of the applied materials and therefore are decisive for the final quality and mechanical properties of the joint. Such melting processes are often not well- understood because - compared to other fields of solidification science - relatively little research has been done on melting by now. Also, regarding microstructure simulation, melting has been strongly neglected in the past, although this process is substantially different from solidification due to the reversed diffusivities of the involved phases. In this paper we present phase-field simulations showing melting, solidification and precipitation of intermetallic phases during diffusion brazing of directionally solidified and heat-treated high-alloyed Ni- based gas turbine blade material using different boron containing braze alloys. Contrary to the common belief, melting of the base material is not always planar and can be further accompanied by detached nucleation and growth of a second liquid phase inside the base material leading to polycrystalline morphologies of the joint after solidification. These findings are consistent with results from brazed laboratory samples, which were characterized by EDX and optical microscopy, and can be explained in terms of specific alloy thermodynamics and inter-diffusion kinetics. Consequences of the gained new understanding for brazing of high- alloyed materials are discussed.

  14. An Ag based brazing system with a tunable thermal expansion for the use as sealant for solid oxide cells

    DEFF Research Database (Denmark)

    Kiebach, Wolff-Ragnar; Engelbrecht, Kurt; Grahl-Madsen, Laila

    2016-01-01

    An Ag-Al2TiO5 composite braze was developed and successfully tested as seal for solid oxide cells. The thermo-mechanical properties of the Ag-Al2TiO5 system and the chemical compatibility between this composite braze and relevant materials used in stacks were characterized and the leak rates...... as a function of the operation temperature were measured. The thermal expansion coefficient in the Ag-Al2TiO5 system can be tailored by varying the amount of the ceramic filler. The brazing process can be carried out in air, the joining partners showed a good chemical stability and sufficient low leak rates...... were demonstrated. Furthermore, the long-term stability of the Ag-Al2TiO5 composite braze was studied under relevant SOFC and SOEC conditions. The stability of brazed Crofer/Ag-Al2TiO5/NiO-YSZ assemblies in reducing atmosphere and in pure oxygen was investigated over 500 h at 850 °C. Additionally...

  15. Interface microstructure of the brazed zirconia and Ti-6Al-4V using Ti-based amorphous filler

    Directory of Open Access Journals (Sweden)

    Liu Y.

    2013-01-01

    Full Text Available The polycrystalline ZrO2−3mol.%Y2O3 was brazed to Ti-6Al-4V using a Ti47Zr28Cu14Ni11 (at.% amorphous ribbon at 1123 K in a high vacuum. The microstructure of the interface and evolution mechanism of the joint was investigated. The experimental result showed that the typical interfacial microstructures of the joints consisted of ZrO2/TiO+TiO2+Cu2Ti4O+Ni2Ti4O/α-Ti+(Ti,Zr2(Cu,Ni eutectic/(Ti,Zr2(Cu,Ni/acicular Widmanstäten structure/Ti-6Al-4V alloy. The microstructure of the brazed joint was related to the solution and chemical reaction among atoms during brazing. According to the mechanical property tests the joint brazed at 1123 K for 30 min obtained the maximum shear strength 63 MPa. Both the white block intermetallic compound (Ti,Zr2(Cu,Ni and the coarse α-Ti+(Ti,Zr2(Cu,Ni eutectic structure should be avoided forming in the brazed joint.

  16. Synthesis and characterization of Ni-Mo filler brazing alloy for Mo-W joining for microwave tube technology

    Directory of Open Access Journals (Sweden)

    Frank Ferrer Sene

    2013-04-01

    Full Text Available A brazing process based on Ni-Mo alloy was developed to join porous tungsten cathode bottom and dense molybdenum cathode body for microwave tubes manufacture. The Ni-Mo alloy was obtained by mixing and milling powders in the eutectic composition, and applied on the surface of the components. The brazing was made at 1400 °C by using induction heating in hydrogen for 5 minutes. Alumina surfaces were coated with the binder and analyzed by Energy Dispersive X-rays Fluorescence. The brazed samples were analyzed by Scanning Electron Microscopy coupled to Energy Dispersive Spectroscopy. Stress-strain tests were performed to determine the mechanical behavior of the joining. The quality of the brazing was evaluated by assuring the presence of a "meniscus" formed by the Ni-Mo alloy on the border of the tungsten and molybdenum joint, the absence of microstructural defects in the interface between the tungsten and molybdenum alloys, and the adhesion of the brazed components.

  17. Wettability between molten slag and dolomitic refractory

    OpenAIRE

    Shen, Ping; Zhang, Lifeng; Wang, Yi; Sridhar, Seetharaman; Wang, Qiangqiang

    2016-01-01

    In the current study, the wettability between molten slag and dolomitic refractory materials used in the ladle during steel refining was investigated. The contact angle between molten slag and dolomitic substrate decreased with increasing temperature. The slag with lower basicity spread on the substrate more easily and penetrated deeper into the substrate. The penetration depth of slag into the refractory increased with the extension of holding time. The CaO in the refractory dissolved into s...

  18. Interfacial Behavior and Its Effect on Mechanical Properties of Cf/SiC Composite/TiAl6V4 Joint Brazed with TiZrCuNi

    Science.gov (United States)

    Fan, Dongyu; Huang, Jihua; Cui, Bing; Yang, Jian; Chen, Shuhai; Zhao, Xingke

    2017-03-01

    In order to characterize the interfacial behavior of brazed joints and offer theoretical basis for the applications of TiZrCuNi-based composite fillers, Cf/SiC composite and TC4 were brazed by TiZrCuNi filler, and the microstructures of joints versus temperature and versus holding time were systematically studied in this paper. The mechanical properties of brazed joints were measured and analyzed. The results showed that Ti(Zr)C, Ti5Si3, Ti2Cu, TiNi, TiZrCu2, Ti2(Cu,Ni) and Ti(s,s) were the predominant compounds in the joints. Brazing temperature had a distinct effect on the microstructures of joints: with the increase of brazing temperature, the structure of brazed joints was reduced from four parts to three parts, and the wavy reaction layer became continuous and much thicker. While holding time had a similar but weaker effect on microstructures: with the extension of holding time, the reaction layer became thicker, but it was difficult to induce the decrease in the structural parts of joint. The thickness of reaction layer determined the mechanical properties of joints. The results were beneficial for the selection of reinforced phases and the design of composite fillers to obtain better mechanical performances. When the brazing temperature was 940 °C and the holding time was 25 min, the maximum shear strength of brazed joints attained a value of 143.2 MPa.

  19. Refractory, Abrasive and Other Industrial Mineral Operations

    Data.gov (United States)

    Department of Homeland Security — This map layer includes refractory, abrasive, and other industrial minerals operations in the United States. The data represent commodities covered by the Minerals...

  20. Refractory organic substances in the environment

    National Research Council Canada - National Science Library

    Frimmel, F. H

    2002-01-01

    ... and its Quality Control in Fractions of Refractory Organic Substances and the Corresponding Original Water Samples 39 Introduction 39 Description of Analytical Methods 41 Sample Treatment 41 Fl...

  1. The improvement of slagging gasifier refractories

    Energy Technology Data Exchange (ETDEWEB)

    Kwong, K.-S.; Bennett, J.P.; Powell, C.A.; Krabbe, R.A.

    2006-03-01

    Refractories play a vital role in slagging gasifier on-line availability and profitability for the next clean power generation system. A recent survey of gasifier users by USDOE indicated that a longer service life of refractories is the highest need among gasifier operators. Currently, Cr2O3 based refractories, the best of commercially available materials for use in slagging gasifiers, last between 3 and 24 months. Researchers at Albany Research Center (ARC) have identified structural spalling, caused by slag penetration, as one of the major failure mechanisms of Cr2O3 refractories through postmortem analysis. New Cr2O3 refractories with phosphate additives have been developed by ARC to decrease slag penetration and thus structural spalling. Laboratory physical property tests indicated that ARC developed refractories are superior to other commercial bricks. One of the ARC developed phosphate containing refractories has been installed in a slagging gasifier. Preliminary results of the performance of this refractory in the gasifier will be reported along with research to develop non-chromia refractories.

  2. Bonding Diamond To Metal In Electronic Circuits

    Science.gov (United States)

    Jacquez, Andrew E.

    1993-01-01

    Improved technique for bonding diamond to metal evolved from older technique of soldering or brazing and more suitable for fabrication of delicate electronic circuits. Involves diffusion bonding, developed to take advantage of electrically insulating, heat-conducting properties of diamond, using small diamond bars as supports for slow-wave transmission-line structures in traveling-wave-tube microwave amplifiers. No fillets or side coats formed because metal bonding strips not melted. Technique also used to mount such devices as transistors and diodes electrically insulated from, but thermally connected to, heat sinks.

  3. Iron refractory iron deficiency anemia

    Science.gov (United States)

    De Falco, Luigia; Sanchez, Mayka; Silvestri, Laura; Kannengiesser, Caroline; Muckenthaler, Martina U.; Iolascon, Achille; Gouya, Laurent; Camaschella, Clara; Beaumont, Carole

    2013-01-01

    Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in adulthood. The disease is refractory to oral iron treatment but shows a slow response to intravenous iron injections and partial correction of the anemia. To date, 40 different Matriptase-2 mutations have been reported, affecting all the functional domains of the large ectodomain of the protein. In vitro experiments on transfected cells suggest that Matriptase-2 cleaves Hemojuvelin, a major regulator of hepcidin expression and that this function is altered in this genetic form of anemia. In contrast to the low/undetectable hepcidin levels observed in acquired iron deficiency, in patients with Matriptase-2 deficiency, serum hepcidin is inappropriately high for the low iron status and accounts for the absent/delayed response to oral iron treatment. A challenge for the clinicians and pediatricians is the recognition of the disorder among iron deficiency and other microcytic anemias commonly found in pediatric patients. The current treatment of iron refractory iron deficiency anemia is based on parenteral iron administration; in the future, manipulation of the hepcidin pathway with the aim of suppressing it might become an alternative therapeutic approach. PMID:23729726

  4. Effect of welding speed on microstructural evolution and mechanical properties of laser welded-brazed Al/brass dissimilar joints

    Science.gov (United States)

    Zhou, L.; Luo, L. Y.; Tan, C. W.; Li, Z. Y.; Song, X. G.; Zhao, H. Y.; Huang, Y. X.; Feng, J. C.

    2018-01-01

    Laser welding-brazing process was developed for joining 5052 aluminum alloy and H62 brass in butt configuration with Zn-15%Al filler. Effect of welding speed on microstructural characteristics and mechanical properties of joints were investigated. Acceptable joints without obvious defect were obtained with the welding speed of 0.5-0.6 m/min, while lower and higher welding speed caused excessive back reinforcement and cracking, respectively. Three reaction layers were observed at welding speed of 0.3 m/min, which were Al4.2Cu3.2Zn0.7 (τ‧)/Al4Cu9/CuZn from weld seam side to brass side; while at welding speed of 0.4-0.6 m/min, two layers Al4.2Cu3.2Zn0.7 and CuZn formed. The thickness of interfacial reaction layers increased with the decrease of welding speed, but varied little at different interfacial positions from top to bottom in one joint. Tensile test results indicated that the maximum joint tensile strength of 128 MPa was obtained at 0.5 m/min, which was 55.7% of that of Al base metal. All the joints fractured along the weld seam/brass interface. Some differences were found regarding fracture locations with three and two reaction layers. The joint fractured between Al4Cu9 and τ‧ IMC layer when the interface had three layers, while the crack occurred between CuZn and τ‧ phase in the case of two layers.

  5. Electrochemical depth profiling of multilayer metallic structures: An aluminum brazing sheet

    DEFF Research Database (Denmark)

    Afshar, F. Norouzi; Ambat, R.; Kwakernaak, C.

    2012-01-01

    potential, cathodic and anodic reactivities, and tracking their changes as a function of depth, the evolution of electrochemical responses through out the material thickness were analyzed and correlated to the corresponding microstructural features. Polarization curves in 1wt% NaCl solution at pH 2.8 were...... obtained at different depths from the surface using controlled sputtering in a glow discharge optical emission spectrometer as a sample preparation technique. The anodic and cathodic reactivity of the top surface areas were significantly higher than that of the bulk, thus indicating these areas to be more...... susceptible to localized attack. Consistent with this, optical microscopy and scanning electron microscope analysis revealed a relatively high density of fine intermetallic and silicon particles at these areas. The corrosion mechanism of the top layers was identified to be intergranular and pitting corrosion...

  6. Effect of ultrasonic transmission rate on microstructure and properties of the ultrasonic-assisted brazing of Cu to alumina.

    Science.gov (United States)

    Ji, Hongjun; Chen, Hao; Li, Mingyu

    2017-01-01

    Fluxless brazing of bare alumina with Cu was conducted with an ultrasonic-assisted brazing technique by a Zn-14wt.%Al filler. The shear strength of Cu/alumina joints (84MPa) exhibited 27% larger than the alumina/Cu joints (66MPa) due to different intermetallic phases and their morphologies formed in the seam under the same parameters, which are probably attributed to the transmission rate of ultrasonic energy varying with density of the ultrasonic horn-contacted materials. Overgrowth of stalactite-like CuZn5 contributes to better thermal dissipation of the ultrasonic-assisted brazed Cu/alumina joints. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Effect of Microstructural Evolution on Sagging Behavior of Cold-Rolled Aluminum Foil During the Brazing Thermal Cycle

    Science.gov (United States)

    Liu, Canwei; Xue, Xili; Chen, Xin; Li, Long; Xia, Chengdong; Zhong, Zhaojun; Zhou, Dejing

    2017-11-01

    Effect of microstructural evolution on sagging behavior of aluminum foil was investigated during the brazing thermal cycle. During the brazing thermal cycle, the sagging behavior consists of three stages: slight sagging stage, accelerative sagging stage and slow sagging stage. The sagging of cold-rolled aluminum foil mainly occurs in the accelerative sagging stage, which is governed by recovery under external stress in the sagging test. The coarse recrystallized grain is responsible for the slow sagging stage by reducing grain boundary sliding. Increasing cold-rolled reduction and addition of final annealing heat treatment can improve sagging resistance by shortening recovery process during the brazing thermal cycle. Dissolution of dispersoids has few effects on sagging deformation.

  8. Joining of aluminum and stainless steel using AlSi10 brazing filler: Microstructure and mechanical properties

    Science.gov (United States)

    Fedorov, Vasilii; Uhlig, Thomas; Wagner, Guntram

    2017-07-01

    Joining of dissimilar materials like stainless steel and aluminum is of special interest for automotive applications. Due to the different properties of these materials, suitable joining techniques are required. Brazing offers the possibilities to manufacture high performance joints in one step and at low joining temperatures. However, these joints often need to withstand a high number of high cyclic loads during application. Therefore, in addition to the monotonic properties, the fatigue behavior of the produced joints must be considered and evaluated. In the present work, specimens are manufactured by induction brazing using an AlSi10 filler and a non-corrosive flux. The mechanical properties are determined by tensile shear tests as well as in fatigue tests at ambient and elevated temperatures. The microstructure of the brazed joints and the fracture surfaces of the tested samples are investigated by SEM.

  9. Genetics Home Reference: iron-refractory iron deficiency anemia

    Science.gov (United States)

    ... refractory iron deficiency anemia Iron-refractory iron deficiency anemia Printable PDF Open All Close All Enable Javascript ... expand/collapse boxes. Description Iron-refractory iron deficiency anemia is one of many types of anemia , which ...

  10. Microstructure of the Transitional Area of the Connection of a High-temperature Ni-based Brazing Alloy and Stainless Steel AISI 321 (X6CrNiTi 18–10)

    OpenAIRE

    R. Augustin; R. Koleňák

    2010-01-01

    This paper presents a detailed examination of the structure of the transitional area between a brazing alloy and the parent material, the dimensions of the diffusion zones that are created, and the influence on them of a change in the brazing parameters. Connections between Ni-based brazing alloys (NI 102) with a small content of B and AISI 321 stainless steel (X6CrNiTi 18–10) were created in a vacuum (10−2 Pa) at various brazing temperatures and for various holding times at the brazing tempe...

  11. An Ag based brazing system with a tunable thermal expansion for the use as sealant for solid oxide cells

    Science.gov (United States)

    Kiebach, Ragnar; Engelbrecht, Kurt; Grahl-Madsen, Laila; Sieborg, Bertil; Chen, Ming; Hjelm, Johan; Norrman, Kion; Chatzichristodoulou, Christodoulos; Hendriksen, Peter Vang

    2016-05-01

    An Ag-Al2TiO5 composite braze was developed and successfully tested as seal for solid oxide cells. The thermo-mechanical properties of the Ag-Al2TiO5 system and the chemical compatibility between this composite braze and relevant materials used in stacks were characterized and the leak rates as a function of the operation temperature were measured. The thermal expansion coefficient in the Ag-Al2TiO5 system can be tailored by varying the amount of the ceramic filler. The brazing process can be carried out in air, the joining partners showed a good chemical stability and sufficient low leak rates were demonstrated. Furthermore, the long-term stability of the Ag-Al2TiO5 composite braze was studied under relevant SOFC and SOEC conditions. The stability of brazed Crofer/Ag-Al2TiO5/NiO-YSZ assemblies in reducing atmosphere and in pure oxygen was investigated over 500 h at 850 °C. Additionally, a cell component test was performed to investigate the durability of the Ag-Al2TiO5 seal when exposed to dual atmosphere. The seals performed well over 900 h under electrolysis operation conditions (-0.5 A cm2, 850 °C), and no cell degradation related to the Ag-Al2TiO5 sealing was found, indicating that the developed braze system is applicable for the use in SOFC/SOEC stacks.

  12. Neuroimaging evaluation in refractory epilepsy.

    Science.gov (United States)

    Granados, Ana M; Orejuela, Juan F; Rodriguez-Takeuchi, Sara Y

    2015-10-01

    To describe the application of neuroimaging analysis, compared to neuropsychological tests and video-electroencephalogram, for the evaluation of refractory epilepsy in a reference centre in Cali, Colombia. Between March 2013 and November 2014, 29 patients, 19 men and 10 women, aged 9-65 years and with refractory epilepsy, were assessed by structural and functional magnetic resonance imaging while performing tasks related to language, verbal and non-verbal memory. Also, volumetric evaluation was performed. A 1.5 Tesla magnetic resonance imaging scanner was used in all cases. Neuroimaging evaluation identified 13 patients with mesial temporal sclerosis. The remaining patients were classified as: 10 patients with neoplastic masses, two patients with cortical atrophy, two patients with scarring lesions and two patients with non-structural aetiology. Among patients with mesial temporal sclerosis, comparison between techniques for lateralising the epileptogenic foci was made; the κ index between functional magnetic resonance imaging and hippocampi volumetry was κ=1.00, agreement between neuroimaging and video-electroencephalogram was good (κ=0.78) and comparison with a neuropsychological test was mild (κ=0.24). Neuroimaging studies allow the assessment of functional and structural damage related to epileptogenic lesions and foci, and are helpful to select surgical treatment, conduct intraoperative neuronavigation techniques, predict surgical deficits and evaluate patient recovery. © The Author(s) 2015.

  13. Mechanisms of wetting and brazing of silicon carbide by Cu-Si non reactive alloys for high temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Gasse, A.; Chaumat, G. [Association Euratom-CEA, Centre d`Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Rado, C.; Eustathopoulos, N. [Institut National Polytechnique, 38 - Grenoble (France)

    1995-12-31

    Sessile drop experiments were carried out with a non reactive Cu 24 at % Si alloy on {alpha}-SiC single crystals and polycrystalline substrates under high vacuum or a commercial argon atmosphere. Experiments led to contact angles as low as 30 deg. and to a non reactive and strong interface. Wetting kinetics observed in this system has been identified to depend greatly on temperature and atmosphere. Brazing experiments were then performed using informations from sessile drop experiments. Influence of the brazing configuration is discussed. (author) 11 refs.

  14. Studies and research on the crack testing for brazed aluminium alloys specimens

    Science.gov (United States)

    Dimitescu, A.; Babiş, C.; Niţoi, D. F.; Radu, C.

    2017-08-01

    The scope of this paper is the identification of an optimum technological solution for brazing aluminum alloys using crack tested specimens. To obtain conclusive results, these tests are conducted on two sets of different specimens. Thus, we get two sets of data which we will compare. These tests are part of the standardized series of tests required by the ASME standards. These are called exfoliation tests. They are used to determine where the crack occurs: in the base material or in the filler material. Thus, we can determine whether the cracking is cohesive or adhesive.

  15. Automating a precision braze paste dispensing operation using non- contact sensing

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, D; Novak, J [Sandia National Labs., Albuquerque, NM (United States); Maslakowski, J; Thiele, A [Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.

    1993-01-01

    This paper describes a collaborative effort between Sandia National Laboratories and the Rocketdyne Division of Rockwell International Corporation to develop an automated braze paste dispensing system for rocket engine nozzle manufacturing. The motivation for automating this manufacturing process is to reduce the amount of labor and excess material required. A critical requirement for this system is the automatic location of key nozzle features using non-contact sensors. Sandia has demonstrated that the low-cost Multi-Axis Seam Tracking (MAST) capacitive sensor can be used to accurately locate the nozzle surface and tube gaps.

  16. Note: Magnification of a polarization angle with a Littrow layout brazed grating

    Energy Technology Data Exchange (ETDEWEB)

    Sasao, H., E-mail: sasao.hajime@jaea.go.jp; Kubo, H.; Kawano, Y.; Itami, K. [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-shi, Ibaraki 311-0193 (Japan); Arakawa, H., E-mail: arakawa@fmt.teikyo-u.ac.jp [Faculty of Fukuoka Medical Technology, Teikyo University, 6-22 Misaki-machi, Omuta-shi, Fukuoka 836-8505 (Japan)

    2014-08-15

    A new method to magnify a small polarization angle with brazed gratings has been developed. In the method, difference in diffraction efficiency for S and P polarization components is used. The magnification dependence on the incident angle can be small by arranging the grating in Littrow layout. A magnification with a factor ∼2.7 has been demonstrated for a 10.6 μm CO{sub 2} laser beam as expected from a calculation. The method is applicable in many polarimetry fields.

  17. Effect of Ni-P alloy coating on microstructures and properties of vacuum brazed joints of SiCp/Al composites

    Science.gov (United States)

    Wang, Peng; Gao, Zeng; Cheng, Dongfeng; Xu, Dongxia; Niu, Jitai

    2017-03-01

    Compared without electroless Ni-P alloy coating on the SiCp/Al composites, the paper describes the effect of Ni-P deposited layer on the microstructure evolution, shear strength, airtightness and fracture behavior of vacuum brazed joints. Void free and compact reaction layers along the 6063Al/Ni-P deposited layer/filler metal interfaces indicated that the joints exhibit high airtightness with He-leakage less than 2.0 × 10-8 Pa ṡm3/s. Energy Dispersive X-ray Spectroscopy (EDS) analysis showed that the reaction layers mainly included brittle Al-Ni and Al-Cu-Ni intermetallics, where fracture occurred in priority and the shear strength was less than 90 MPa. However, without Ni-P alloy coating, sound joints with high shear strength of 100.1 MPa but low airtightness with He-leakage higher than 1.45 × 10-7Pa ṡm3/s were also obtained at 590∘C for soaking time of 30 min. In this case, a few holes that occurred along the filler metal/SiC particle interface significantly decreased the compactness of the joints. Therefore, according to the requirements in practical applications, suitable choice was provided in this research.

  18. Refractory for Black Liquor Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Musa Karakus; Xiaoting Laing

    2005-10-01

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  19. REFRACTORY FOR BLACK LIQUOR GASIFIERS

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Musa Karakus; Jun Wei

    2005-03-01

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  20. Evaluation of mechanically alloyed Cu-based powders as filler alloy for brazing tungsten to a reduced activation ferritic-martensitic steel

    Science.gov (United States)

    de Prado, J.; Sánchez, M.; Ureña, A.

    2017-07-01

    80Cu-20Ti powders were evaluated for their use as filler alloy for high temperature brazing of tungsten to a reduced activation ferritic/martensitic steel (Eurofer), and its application for the first wall of the DEMO fusion reactor. The use of alloyed powders has not been widely considered for brazing purposes and could improve the operational brazeability of the studied system due to its narrower melting range, determined by DTA analysis, which enhances the spreading capabilities of the filler. Ti contained in the filler composition acts as an activator element, reacting and forming several interfacial layers at the Eurofer-braze, which enhances the wettability properties and chemical interaction at the brazing interface. Brazing thermal cycle also activated the diffusion phenomena, which mainly affected to the Eurofer alloying elements causing in it a softening band of approximately 400 μm of thickness. However, this softening effect did not degrade the shear strength of the brazed joints (94 ± 23 MPa), because failure during testing was always located at the tungsten-braze interface.

  1. NASA research on refractory compounds.

    Science.gov (United States)

    Gangler, J. J.

    1971-01-01

    The behavior and properties of the refractory carbides, nitrides, and borides are being investigated by NASA as part of its research aimed at developing superior heat resistant materials for aerospace applications. Fundamental studies on the electronic and defect structures of the carbides indicate that there is promise for improving the strength and ductility of these materials. Studies of the zirconium-carbon-oxygen system show that zirconium oxycarbides of different compositions and lattice parameters can be formed between 1500 and 1900 C and are stable below 1500 C. More applied studies show that hot working generally improves the microstructure and therefore the strength of TiC and NbC. Sintering studies on UN indicate that very high densities can be achieved. Hot pressing of cermets of HfN and HfC produces good mechanical properties for high temperature bearing applications.

  2. REFRACTORY FOR BLACK LIQUOR GASIFIERS

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Musa Karakus; Xiaoting Liang; Alireza Rezaie

    2004-07-01

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  3. REFRACTORY FOR BLACK LIQUOR GASIFIERS

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Musa Karakus; Xiaoting Liang; Alireza Rezaie

    2004-10-01

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  4. Refractory for Black Liquor Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Musa Karakus; Xiaoting Liang

    2005-10-01

    The University of Missouri-Rolla identified materials that permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project was to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study attempted to define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials were selected/developed that either react with the gasifier environment to form protective surfaces in

  5. REFRACTORY FOR BLACK LIQUOR GASIFIERS

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Musa Karakus; Xiaoting Liang

    2005-07-01

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  6. REFRACTORY FOR BLACK LIQUOR GASIFIERS

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Musa Karakus; Xiaoting Liang; Jun Wei

    2005-01-01

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  7. Refractory for Black Liquor Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Alireza Rezaie; Xiaoting Liang; Musa Karakus; Jun Wei

    2005-12-01

    The University of Missouri-Rolla identified materials that permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project was to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study attempted to define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials were selected or developed that reacted with the gasifier environment to form protective surfaces in

  8. REFRACTORY FOR BLACK LIQUOR GASIFIERS

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Musa Karakus; Xiaoting Liang; Jun Wei

    2005-04-01

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the material problems encountered during the operation of low-pressure high-temperature (LPHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  9. REFRACTORY FOR BLACK LIQUOR GASIFIERS

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr.; Alireza Rezaie

    2003-12-01

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the materials problems encountered during the operation of low-pressure high-temperature (LFHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  10. Refractory for Black Liquor Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Alireza Rezaie

    2003-08-01

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the materials problems encountered during the operation of low-pressure high-temperature (LFHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  11. Refractory for Black Liquor Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    William L. Headrick Jr; Alireza Rezaie

    2003-12-01

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the materials problems encountered during the operation of low-pressure high-temperature (LFHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  12. Refractory for Black Liquor Gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    Robert E. Moore; William L. Headrick; Alireza Rezaie

    2003-03-31

    The University of Missouri-Rolla will identify materials that will permit the safe, reliable and economical operation of combined cycle gasifiers by the pulp and paper industry. The primary emphasis of this project will be to resolve the materials problems encountered during the operation of low-pressure high-temperature (LFHT) and low-pressure low-temperature (LPLT) gasifiers while simultaneously understanding the materials barriers to the successful demonstration of high-pressure high-temperature (HPHT) black liquor gasifiers. This study will define the chemical, thermal and physical conditions in current and proposed gasifier designs and then modify existing materials and develop new materials to successfully meet the formidable material challenges. Resolving the material challenges of black liquor gasification combined cycle technology will provide energy, environmental, and economic benefits that include higher thermal efficiencies, up to three times greater electrical output per unit of fuel, and lower emissions. In the near term, adoption of this technology will allow the pulp and paper industry greater capital effectiveness and flexibility, as gasifiers are added to increase mill capacity. In the long term, combined-cycle gasification will lessen the industry's environmental impact while increasing its potential for energy production, allowing the production of all the mill's heat and power needs along with surplus electricity being returned to the grid. An added benefit will be the potential elimination of the possibility of smelt-water explosions, which constitute an important safety concern wherever conventional Tomlinson recovery boilers are operated. Developing cost-effective materials with improved performance in gasifier environments may be the best answer to the material challenges presented by black liquor gasification. Refractory materials may be selected/developed that either react with the gasifier environment to form protective

  13. Primordial Compositions of Refractory Inclusions

    Energy Technology Data Exchange (ETDEWEB)

    Grossman, L; Simon, S B; Rai, V K; Thiemens, M H; Hutcheon, I D; Williams, R W; Galy, A; Ding, T; Fedkin, A V; Clayton, R N; Mayeda, T K

    2008-02-20

    Bulk chemical and oxygen, magnesium and silicon isotopic compositions were measured for each of 17 Types A and B refractory inclusions from CV3 chondrites. After bulk chemical compositions were corrected for non-representative sampling in the laboratory, the Mg and Si isotopic compositions of each inclusion were used to calculate its original chemical composition assuming that the heavy-isotope enrichments of these elements are due to Rayleigh fractionation that accompanied their evaporation from CMAS liquids. The resulting pre-evaporation chemical compositions are consistent with those predicted by equilibrium thermodynamic calculations for high-temperature nebular condensates but only if different inclusions condensed from nebular regions that ranged in total pressure from 10{sup -6} to 10{sup -1} bar, regardless of whether they formed in a system of solar composition or in one enriched in OC dust relative to gas by a factor of ten relative to solar composition. This is similar to the range of total pressures predicted by dynamic models of the solar nebula for regions whose temperatures are in the range of silicate condensation temperatures. Alternatively, if departure from equilibrium condensation and/or non-representative sampling of condensates in the nebula occurred, the inferred range of total pressure could be smaller. Simple kinetic modeling of evaporation successfully reproduces observed chemical compositions of most inclusions from their inferred pre-evaporation compositions, suggesting that closed-system isotopic exchange processes did not have a significant effect on their isotopic compositions. Comparison of pre-evaporation compositions with observed ones indicates that 80% of the enrichment in refractory CaO + Al{sub 2}O{sub 3} relative to more volatile MgO + SiO{sub 2} is due to initial condensation and 20% due to subsequent evaporation for both Type A and Type B inclusions.

  14. Reduction of Liquid Clad Formation Due to Solid State Diffusion in Clad Brazing Sheet

    Science.gov (United States)

    Benoit, Michael J.; Whitney, Mark A.; Wells, Mary A.; Winkler, Sooky

    2016-12-01

    Warm forming operations have shown promise in expanding automotive heat exchanger designs by increasing forming limits of clad brazing sheet. The impact of isothermal holds below the clad melting temperature on subsequent brazeability has not previously been studied in detail. The effect of these holds on brazeability, as measured by the clad thickness loss due to solid state diffusion of Si out of the clad layer prior to clad melting, was assessed through parallel DSC and optical microscopy measurements, as well as through the use of a previously developed model. EPMA measurements were also performed to support the other measures. Overall, the same trends were predicted by DSC, microscopy, and the theoretical model; however, the DSC predictions were unable to accurately predict remaining clad thickness prior to melting, even after correcting the data for clad-core interactions. Microscopy measurements showed very good agreement with the model predictions, although there were slight discrepancies at short hold times due to the inability of the model to account for clad loss during heating to the brazing temperature. Further microscopy measurements showed that when the heating rate is set below a critical value, there is a reduction in the clad thickness from the as-received condition.

  15. Effects of different brazing and welding methods on the fracture load of various orthodontic joining configurations.

    Science.gov (United States)

    Bock, Jens J; Bailly, Jacqueline; Fuhrmann, Robert A

    2009-06-01

    The aim of this study was to compare the fracture load of different joints made by conventional brazing, tungston inert gas (TIG) and laser welding. Six standardized joining configurations of spring hard quality orthodontic wire were investigated: end-to-end, round, cross, 3 mm length, 9 mm length and 6.5 mm to orthodontic band. The joints were made by five different methods: brazing with universal silver solder, two TIG and two laser welding devices. The fracture loads were measured with a universal testing machine (Zwick 005). Data were analysed with the Mann-Whitney-Wilcoxon and Kruskal-Wallis tests. The significance level was set at PTIG or laser welding (Pwelding (826 N). No differences between the various TIG or laser welding devices were demonstrated, although it was not possible to join an orthodontic wire to an orthodontic band using TIG welding. For orthodontic purposes laser and TIG welding are solder free alternatives. TIG welding and laser welding showed similar results. The laser technique is an expensive, but sophisticated and simple method.

  16. Study on the Microstructure and Wettability of an Al-Cu-Si Braze Containing Small Amounts of Rare Earth Erbium

    Science.gov (United States)

    Shi, Yaowu; Yu, Yang; Li, Yapeng; Xia, Zhidong; Lei, Yongping; Li, Xiaoyan; Guo, Fu

    2009-04-01

    The effect of adding small amounts of rare earth Er on the microstructure of an Al-Cu-Si braze alloy has been investigated. Several Al-20Cu-7Si braze alloys containing various contents of Er were prepared, and their melting temperature, microstructure, hardness, and wettability in contact with 3003 aluminum alloy substrates were determined. The results indicate that the constituents of the microstructure of Al-20Cu-7Si-Er braze alloys are similar to those in the Al-20Cu-7Si alloy, and comprise of solid solutions of aluminum, silicon, and the intermetallic compound CuAl2. When the Er content increases, the size of the Al phase decreases, and the needle-like Si phase is thickened, and transformed to a blocky shape. Moreover, small amounts of Er can improve the wettability and hardness of the Al-20Cu-7Si braze alloy; however, the melting temperature of the Al-20Cu-7Si alloy does not change.

  17. Elevated Temperature Creep Properties of Conventional 50Au-50Cu and 47Au 50Cu-3Ni Braze Alloys

    Energy Technology Data Exchange (ETDEWEB)

    STEPHENS JR.,JOHN J.; SCHMALE,DAVID T.

    2000-12-18

    The elevated temperature creep properties of the 50Au-50Cu wt% and 47Au-50Cu-3Ni braze alloys have been evaluated over the temperature range 250-850 C. At elevated temperatures, i.e., 450-850 C, both alloys were tested in the annealed condition (2 hrs. 750 C/water quenched). The minimum strain rate properties over this temperature range are well fit by the Garofalo sinh equation. At lower temperatures (250 and 350 C), power law equations were found to characterize the data for both alloys. For samples held long periods of time at 375 C (96 hrs.) and slowly cooled to room temperature, an ordering reaction was observed. For the case of the 50Au-50Cu braze alloy, the stress necessary to reach the same, strain rate increased by about 15% above the baseline data. The limited data for ordered 47Au-50Cu-3Ni alloy reflected a,smaller strength increase. However, the sluggishness of this ordering reaction in both alloys does not appear to pose a problem for braze joints cooled at reasonable rates following brazing.

  18. Mechanical characterization and modeling of brazed tungsten and Cu-Cr-Zr alloy using stress relief interlayers

    Science.gov (United States)

    Qu, Dandan; Zhou, Zhangjian; Yum, Youngjin; Aktaa, Jarir

    2014-12-01

    A rapidly solidified foil-type Ti-Zr based amorphous filler with a melting temperature of 850 °C was used to braze tungsten to Cu-Cr-Zr alloy for water cooled divertors and plasma facing components application. Brazed joints of dissimilar materials suffer from a mismatch in coefficients of thermal expansion. In order to release the residual stress caused by the mismatch, brazed joints of tungsten and Cu-Cr-Zr alloy using different interlayers were studied. The shear strength tests of brazed W/Cu joints show that the average strength of the joint with a W70Cu30 composite plate interlayer reached 119.8 MPa, and the average strength of the joint with oxygen free high conductivity copper (OFHC Cu)/Mo multi-interlayers reached 140.8 MPa, while the joint without interlayer was only 16.6 MPa. Finite element method (FEM) has been performed to investigate the stress distribution and effect of stress relief interlayers. FEM results show that the maximum von Mises stress occurs in the tungsten/filler interface and that the filler suffers the peak residual stresses and becomes the weakest zone. And the use of OFHC Cu/Mo multi-interlayers can reduce the residual stress significantly, which agrees with the mechanical experiment data.

  19. Advanced high temperature brazing to extend life of single crystal turbine components; Hochtemperaturloeten als Reparaturverfahren zur Erweiterung der Lebensdauer einkristalliner Turbinenkomponenten

    Energy Technology Data Exchange (ETDEWEB)

    Bobzin, K.; Ernst, F.; Roesing, J.; Schlegel, A.; Rojas, Y. [RWTH Aachen (Germany)

    2007-07-01

    The reduction of the boron concentration by introducing hafnium as a further melting point reducing alloy element in the repair braze was successful. Both the mixtures with NiCrHfB brazes and with Amdry775+Hf brazes were capable of reconditioning turbine components made of the superbase alloy CMSX4. In all cases, DSR142 superalloy powder was used as additive material. With all repair mixtures investigated, care was taken to keep the upper limits of the mass fractions of the alloying elements boron (2 percent by weight) and hafnium (7 percent by weight). (orig.)

  20. Brazed multilayer material compounds for operation in stationary Solid Oxide Fuel Cells (SOFC); Geloetete Multilayerwerkstoffverbunde fuer den Einsatz in stationaeren Hochtemperatur-Brennstoffzellen (SOFC)

    Energy Technology Data Exchange (ETDEWEB)

    Kuprin, C.; Meyer, L.W. [Technische Univ. Chemnitz (Germany); Mueller, J.U. [Saxobraze GmbH, Chemnitz (Germany); Krueger, L. [Technische Univ. Freiberg (Germany). Inst. fuer Werkstofftechnik; Reichel, I.; Dautert, T.; Posdziech, O. [EBZ Entwicklungs- und Vertriebsgesellschaft Brennstoffzelle mbH, Dresden (Germany)

    2007-07-01

    Using the example of a modular power supply system on the basis of SOFC high-temperature fuel cells for decentral, stationary or quasistationary applications, vacuum-brazed components are discussed here, i.e. heat transfer units, evaporators, gas distribution systems and adapter plates. The particular requirements of high-temperature components and the function in operating conditions of the 3D composites constructed and brazed by the multilayer principle are discussed. For applications in high-temperature fuel cell systems, brazed multilayer structures make it possible to construct components that cannot be constructed by conventional welding processes. (orig.)

  1. Refractories for Industrial Processing. Opportunities for Improved Energy Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Hemrick, James G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hayden, H. Wayne [Metals Manufacture Process and Controls Technology, Inc., Oak Ridge, TN (United States); Angelini, Peter [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Moore, Robert E. [R.E. Moore Associates, Maricopa, AZ (United States); Headrick, William L. [R.E. Moore Associates, Maricopa, AZ (United States)

    2005-01-01

    Refractories are a class of materials of critical importance to manufacturing industries with high-temperature unit processes. This study describes industrial refractory applications and identifies refractory performance barriers to energy efficiency for processing. The report provides recommendations for R&D pathways leading to improved refractories for energy-efficient manufacturing and processing.

  2. Effect of Injection Smelting Jet Characteristics on Refractory Wear in the Mitsubishi Process

    Science.gov (United States)

    Goto, Moto; Echigoya, Takumi

    1980-11-01

    The Mitsubishi Process is a multi-furnace continuous copper smelting and converting process developed by Mitsubishi Metal Corporation. Developing a furnace lining system to minimize refractory wear in smelting and converting furnaces was one of the major objectives since the pilot plant started operation in 1968. Many efforts were directed toward developing techniques such as thickness control of slag layer, application of water-cooled jackets, fuel combustion control to avoid hot spots, and modification of furnace configuration. These efforts prolonged furnace life by a year, and are expected to extend it to several years in the near future. This paper discusses developments which have reduced refractory wear, and current refractory practice based on recent operating data.

  3. Prognostic Factors for Refractory Status Epilepticus

    Directory of Open Access Journals (Sweden)

    J. Gordon Millichap

    2013-03-01

    Full Text Available Researchers at the Mayo Clinic, Rochester, MN studied the outcome and identified prognostic factors for refractory status epilepticus (RSE in 54 adult patients, median age 52 years [range 18-93].

  4. Testing Consent Order on Refractory Ceramic Fibers

    Science.gov (United States)

    This notice announces that EPA has signed signed an enforceable testing consent order under the Toxic Substances Control Act (TSCA), 15 U.S.C. section 2601 at seq., with three of the primary producers of refractory ceramic fibers (RCF).

  5. Ultra High Temperature Refractory Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Legacy refractory materials that have origins dating to the original Saturn program are commonly used in current launch facilities. Although they failure to meet the...

  6. Ultra High Temperature Refractory Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Legacy refractory materials that have origins dating to the original Saturn program are commonly used in current launch facilities. Although they fail to meet the...

  7. Emergency coronary angioplasty in refractory unstable angina

    NARCIS (Netherlands)

    P.J. de Feyter (Pim); P.W.J.C. Serruys (Patrick); M.J.B.M. van den Brand (Marcel); K. Balakumaran (Kulasekaram); A.L. Soward; P.G. Hugenholtz (Paul); A.E.R. Arnold (Alfred); B. Mochtar (Bas)

    1985-01-01

    textabstractWe performed percutaneous transluminal coronary angioplasty as an emergency procedure in 60 patients with unstable angina pectoris that was refractory to treatment with maximally tolerated doses of beta-blockers, calcium antagonists, and intravenous nitroglycerin. The initial success

  8. Functional outcome of prolonged refractory status epilepticus

    OpenAIRE

    Lai, Alexandre; Outin, Hervé D.; Jabot, Julien; Mégarbane, Bruno; Gaudry, Stéphane; Coudroy, Rémi; Louis, Guillaume; Schneider, Francis; Barbarot, Nicolas; Roch, Antoine; Lerolle, Nicolas; Luis, David; Fourrier, François; Renault, Anne; Argaud, Laurent

    2015-01-01

    International audience; Introduction:To characterize etiology, clinical course and outcomes of patients in prolonged refractory status epilepticus (PRSE) and looking for prognostic factors.Methods:Retrospective study conducted in patients hospitalized from January 1, 2001 to December 31, 2011 in 19 polyvalent intensive care units in French university and general hospitals. Patients were adults with a generalized convulsive refractory status epilepticus that lasted more than seven days, despit...

  9. Molecular Determinants of Hormone Refractory Prostate Cancer

    Science.gov (United States)

    2017-07-01

    Award Number: W81XWH-12-1-0062 TITLE: Molecular Determinants of Hormone Refractory Prostate Cancer PRINCIPAL INVESTIGATOR: Atish Choudhury...CONTRACTING ORGANIZATION: Dana-Farber Cancer Institute Boston, MA 02215 REPORT DATE: July 2017 TYPE OF REPORT: Annual PREPARED FOR: U.S. Army...Determinants of Hormone Refractory Prostate Cancer 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-12-1-0062 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Atish

  10. The Modified Atkins Diet in Refractory Epilepsy

    Directory of Open Access Journals (Sweden)

    Suvasini Sharma

    2014-01-01

    Full Text Available The modified Atkins diet is a less restrictive variation of the ketogenic diet. This diet is started on an outpatient basis without a fast, allows unlimited protein and fat, and does not restrict calories or fluids. Recent studies have shown good efficacy and tolerability of this diet in refractory epilepsy. In this review, we discuss the use of the modified Atkins diet in refractory epilepsy.

  11. REFRACTORY THROMBOCYTOPENIA AND NEUTROPENIA: A DIAGNOSTIC CHALLENGE

    Directory of Open Access Journals (Sweden)

    Emmanuel Gyan

    2015-02-01

    Full Text Available Background. The 2008 WHO classification identified refractory cytopenia with unilineage dysplasia (RCUD as a composite entity encompassing refractory anemia, refractory thrombocytopenia (RT, and refractory neutropenia (RN, characterized by 10% or more dysplastic cells in the bone marrow respective lineage. The diagnosis of RT and RN is complicated by several factors.  Diagnosing RT first requires exclusion of familial thrombocytopenia, chronic auto-immune thrombocytopenia, concomitant medications, viral infections, or hypersplenism. Diagnosis of RN should also be made after ruling out differential diagnoses such as ethnic or familial neutropenia, as well as acquired, drug-induced, infection-related or malignancy-related neutropenia. An accurate quantification of dysplasia should be performed in order to distinguish RT or RN from the provisional entity named idiopathic cytopenia of unknown significance (ICUS. Cytogenetic analysis, and possibly in the future somatic mutation analysis (of genes most frequently mutated in MDS, and flow cytometry analysis aberrant antigen expression on myeloid cells may help in this differential diagnosis. Importantly, we and others found that, while isolated neutropenia and thrombocytopenia are not rare in MDS, those patients can generally be classified (according to WHO 2008 classification as refractory cytopenia with multilineage dysplasia or refractory anemia with excess blasts, while RT and RN (according to WHO 2008 are quite rare.These results suggest in particular that identification of RT and RN as distinct entities could be reconsidered in future WHO classification updates.

  12. Microstructure and mechanical properties of SiO2-BN ceramic and Invar alloy joints brazed with Ag–Cu–Ti+TiH2+BN composite filler

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2016-03-01

    Full Text Available Ag–Cu–Ti + TiH2+BN composite filler was prepared to braze SiO2-BN ceramic and Invar alloy. The interfacial microstructure, mechanical properties, and residual stress distribution of the brazed joints were investigated. The results show that a wave-like Fe2Ti–Ni3Ti structure appears in the Invar substrate and a thin TiN–TiB2 reaction layer forms adjacent to the SiO2-BN ceramic. The added BN particles react with Ti to form TiN–TiB fine-particles, which is beneficial to refine the microstructure of the brazing seam and to greatly inhibit the brittle compounds formation. The interfacial microstructure at various brazing temperatures was analyzed, and the mechanism for the interfacial reactions responsible for the bonding was proposed. The maximum shear strength of the joints brazed with the composite filler at 880 °C for 10 min is 39 MPa, which is 30% greater than that brazed with Ag–Cu–Ti alloy. The improvement of the joint strength is attributed to the variation of joint microstructure and the reduction of tensile stresses induced in the SiO2-BN ceramic. The finite element analysis indicates that the peak tensile stress decreases from 230 to 142 MPa due to the addition of BN particles in the ceramic.

  13. Experimental results for hydrocarbon refrigerant vaporization inside brazed plate heat exchangers at high pressure

    DEFF Research Database (Denmark)

    Desideri, Adriano; Ommen, Torben Schmidt; Wronski, Jorrit

    2016-01-01

    In recent years the interest in small capacity organic Rankine cycle (ORC) power systems for harvesting low qualitywaste thermal energy from industrial processes has been steadily growing. Micro ORC systems are normally equippedwith brazed plate heat exchangers which allows for efficient heat...... transfer with a compact design. An accurate prediction of the heat transfer process characterizing these devices is required from the design phase to the development of modelbased control strategies. The current literature is lacking experimental data and validated correlations for vaporization of organic...... fluids at typical working conditions of ORC systems for low temperature waste heat recovery (WHR) applications. Based on these premises, a novel testrig has been recently designed and built at the Technical University of Denmark to simulate the evaporating condition occurring in a small capacity ORC...

  14. Refractory of Furnaces to Reduce Environmental Impact

    Energy Technology Data Exchange (ETDEWEB)

    Hanzawa, Shigeru, E-mail: hanzawa@ngk.co.jp [NGK Insulators, LTD., Mizuho, Nagoya (Japan)

    2011-10-29

    The energy load of furnaces used in the manufacturing process of ceramics is quite large. Most of the environmental impact of ceramics manufacturing is due to the CO{sub 2} produced from this high energy load. To improve this situation, R and D has focused on furnace systems and techniques of control in order to reduce energy load. Since furnaces are comprised of refractory, consideration of their mechanical and thermal characteristics is important. Herein are described several refractory types which were chosen through comparison of the characteristics which contribute to heat capacity reduction, heat insulating reinforcement and high emissivity, thereby improving thermal radiation heat transfer efficiency to the ceramic articles. One selected refractory material which will reduce the environmental impact of a furnace, chosen considering low heat capacity and high emissivity characteristics, is SiC. In this study, thermal radiation heat transfer efficiency improvement and its effect on ceramic articles in the furnace and oxidation behaviour were investigated at 1700K. A high density SiC refractory, built into the furnace at construction, has relatively high oxidation durability and has the ability to reduce environmental impact-CO{sub 2} by 10 percent by decreasing the furnace's energy load. However, new oxidation prevention techniques for SiC will be necessary for long-term use in industrial furnaces, because passive to active oxidation transition behaviour of commercial SiC refractory is coming to close ideal.

  15. Rational use of refractories in regenerator checkers

    Energy Technology Data Exchange (ETDEWEB)

    Popov, O.N.; Borovkova, L.B.; Izosenkova, A.V.; Shatova, N.P.

    1985-09-01

    The thermal efficiency of regenerators in glass furnaces depends on the rational choice of the checker system and the refractory materials used in their construction. In order to develop practical recommendations for the rational use of refractories in checkers for sheet glass, container, and medical-glass furnaces, the authors carried out an all-around investigation of the resistance of aluminosilicate and magnesia refractories in laboratory conditions, modelling the actual service conditions of the material in the checkers. Magnesite, ordinary MO-89, compressed magnesite MU-91, magnesitechromite ordinary, MKhSO, periclase-spinel ordinary, PShSO, forsterite F, unfired magnesite-chromite BMKh, chamotte ShN-38, and highalumina DV-12 were selected as refractories. The use in checkers of magnesia refractories, bearing in mind their corrosion resistance, and with the elimination of the factors in the damaging action, will enable one to ensure prolonged service for the checkers without carrying out hot repairs during the campaign of furnaces producing sheet, container, and medical glasses.

  16. Roasting of refractory gold and silver concentrate; Tostacion de un concentrado refractario de oro y plata

    Energy Technology Data Exchange (ETDEWEB)

    Coraonado, J. H.; Encinas, M. A.; Leyva, M. A.; Valenzuela, J. L.; Valenzuela, A.; Munive, G. T.

    2012-11-01

    In processing of precious metal ores with high pyrite content, refractory concentrates are obtained, which are difficult to process. A refractory gold and silver concentrate was leached with sodium cyanide. Results show low extraction percentages, being 34 % of gold and 40 % of silver. A roasting method to oxidize the concentrate was used, making it more susceptible to cyanidation, hence a more efficient way to extract precious metals. The variables include roasting temperature and roasting and cyanidation time. In addition, the hot calcine was added to the leaching solution at room temperature to analyze the effect on particle size and recovery. The best results, although not entirely satisfactory (50 % of gold and 61 % of silver) were obtained by roasting the concentrate for 4 h at 600 degree centigrade, followed by cyanidation for 20 h. The lime consumption to raise the pH to about 11.3 was increased markedly to 25 kg/m{sup 3}. (Author) 11 refs.

  17. Modelling Simulation and Comparison of Refractory Corrosion at RHI's Technology Center

    Science.gov (United States)

    Gregurek, Dean; Ressler, Angelika; Franzkowiak, Anna; Spanring, Alfred

    In order to determine the most suitable refractory products and improve the lining lifetime for the diverse furnaces used in the nonferrous metal industry, corrosion tests are performed at RHF's Technology Center. The practical facilities include the cup test, induction furnace, rotary kiln, and drip slag test described in this paper, which enable a comprehensive understanding of the chemo-thermal brick wear on a pilot scale. The corrosion trials are performed with actual slags generated during operations at a customer's plant. To determine the highest influencing wear parameter, every single test is combined with a detailed mineralogical investigation and thermochemical calculations performed using FactSage. Based on the results, tailored refractory solutions for the nonferrous metal industry can be provided in combination with trials conducted at the customer's site.

  18. Analytical and experimental evaluation of joining silicon nitride to metal and silicon carbide to metal for advanced heat engine applications. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kang, S.; Selverian, J.H.; O`Neil, D.; Kim, H. [GTE Labs., Inc., Waltham, MA (US); Kim, K. [Brown Univ., Providence, RI (US). Div. of Engineering

    1993-05-01

    This report summarizes the results of Phase 2 of Analytical and Experimental Evaluation of Joining Silicon Nitride to Metal and Silicon Carbide to Metal for Advanced Heat Engine Applications. A general methodology was developed to optimize the joint geometry and material systems for 650{degrees}C applications. Failure criteria were derived to predict the fracture of the braze and ceramic. Extensive finite element analyses (FEA) were performed to examine various joint geometries and to evaluate the affect of different interlayers on the residual stress state. Also, material systems composed of coating materials, interlayers, and braze alloys were developed for the program based on the chemical stability and strength of the joints during processing, and service. The FEA results were compared with experiments using two methods: (1) an idealized strength relationship of the ceramic, and (2) a probabilistic analysis of the ceramic strength (NASA CARES). The results showed that the measured strength of the joint reached 30--80% of the strength predicted by FEA. Also, potential high-temperature braze alloys were developed and evaluated for the high-temperature application of ceramic-metal joints. 38 tabs, 29 figs, 20 refs.

  19. Fatigue properties of 6061-T6 aluminum alloy butt joints processed by vacuum brazing and tungsten inert gas welding

    Directory of Open Access Journals (Sweden)

    Huei Lin

    2016-04-01

    Full Text Available Tungsten inert gas welding and vacuum brazing butt joints of Al–Mg–Si alloy 6061 in the artificially aged condition T6 were studied. Constant amplitude and variable amplitude fatigue loading tests were performed. The experimental S-N curves were compared with the fatigue design curves recommended by the International Institute of Welding, British Standard, and Eurocode 9. Two mean stress correction methods, Goodman and Gerber, were evaluated. In terms of the size effect on the fatigue life, this article proposed an innovational thickness correction method based on the ratio of the ultimate tensile strengths of specimens with different thickness. For vacuum brazing components, the tensile strength–based thickness correction method was better than the thickness correction methods recommended by the International Institute of Welding and Eurocode 9.

  20. Dramatic response to infliximab in refractory neurosarcoidosis

    Directory of Open Access Journals (Sweden)

    Chintamaneni Sreekanth

    2010-01-01

    Full Text Available Sarcoidosis is a systemic disease characterized by noncaseating granulomas in the involved organs. Neurologic manifestations involving the central and/or peripheral nervous system occur in about 5% of patients. Neurosarcoidosis is often refractory to conventional treatment and therefore more effective treatment options are needed. While the etiology of the disease is still unknown, there is now a better understanding of its pathogenesis on a molecular level. It is clear that tumor necrosis factor-α (TNFα plays a pivotal role in the development of the granulomas and it is believed to be a key cytokine involved in the pathogenesis of the disease. Taking advantage of this better understanding of disease pathogenesis, anti-TNFα agents are being increasingly used to treat refractory sarcoidosis. We report a patient with refractory neurosarcoidosis who showed dramatic improvement in the clinical and radiological manifestations following treatment with infliximab; he suffered a relapse upon discontinuation of the medication.

  1. Treatment of refractory neonatal seizures with topiramate.

    Science.gov (United States)

    Riesgo, Rudimar; Winckler, Maria Isabel; Ohlweiler, Lygia; Ranzan, Josiane; Becker, Michele; Salvador, Socrates; Magalhaes, Luiza; Ribeiro, Ricardo

    2012-12-01

    The objective of this study is to describe the usefulness of topiramate in refractory neonatal seizures. We reported the clinical off-label use of topiramate in three cases of refractory neonatal seizures of unclear origin with no response to conventional antiepileptic drugs. In all cases, the seizures were completely controlled with adding topiramate. All patients became seizure free during hospitalization and were followed by approximately 1 year after hospital discharge, with monotherapy with topiramate. The clinical off-label use of topiramate in neonatal seizures is still incipient. When searching publications in this matter, only one report was identified. Because of its efficacy for both seizures and neuroprotection, topiramate could be a useful choice in refractory neonatal seizures. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  2. Refractory Behaviors of Magnetite-Kaolin Bricks

    Science.gov (United States)

    Adeosun, S. O.; Akpan, E. I.; Gbenebor, O. P.; Taiwo, O. O.; Eke, I. J.

    2016-11-01

    In this work, the suitability of using kaolin-magnetite-plastic clay to produce refractory bricks has been experimentally explored. Thirty bricks of different compositions were produced and fired at 1200°C. The density, shrinkage moisture content, loss on ignition, porosity and permeability of the bricks were examined. Results show that the bricks remained stable during firing and thus possess good insulating characteristics. The highest (2.23 g/cm3) and lowest (2.00 g/cm3) bulk densities obtained in this study are higher than the highest bulk density reported for Al dross-filled refractories (1.23 g/cm3). The bricks also possessed very low effective moisture content (10-23%) and very high compression modulus (16-100 MPa) desirable in insulating refractory bricks with high resistance to abrasion.

  3. Influence of Laser Power on the Microstructure and Mechanical Properties of a Laser Welded-Brazed Mg Alloy/Ni-Coated Steel Dissimilar Joint

    Science.gov (United States)

    Tan, Caiwang; Xiao, Liyuan; Liu, Fuyun; Chen, Bo; Song, Xiaoguo; Li, Liqun; Feng, Jicai

    2017-05-01

    In this work, we describe a method to improve the bonding of an immiscible Mg/steel system using Ni as an interlayer by coating it on the steel surface. Laser welding-brazing of AZ31B Mg alloy to Ni-coated Q235 steel using Mg-based filler was performed in a lap configuration. The influence of laser power on the weld characteristics, including joint appearance, formation of interfacial reaction layers and mechanical properties was investigated. The results indicated that the presence of the Ni-coating promoted the wetting of the liquid filler metal on the steel surface. A thermal gradient along the interface led to the formation of heterogeneous interfacial reaction layers. When using a low laser power of 1600 W, the reaction products were an FeAl phase in the direct laser irradiation zone, an AlNi phase close to the intermediate zone and mixtures of AlNi phase and an (α-Mg + Mg2Ni) eutectic structure near the interface at the seam head zone. For high powers of more than 2000 W, the FeAl phase grew thicker in the direct laser irradiation zone and a new Fe(Ni) transition layer formed at the interface of the intermediate zone and the seam head zone. However, the AlNi phase and (α-Mg + Mg2Ni) eutectic structure were scattered at the Mg seam. All the joints fractured at the fusion zone, indicating that the improved interface was not the weakest joint region. The maximum tensile-shear strength of the Mg/Ni-coated steel joint reached 190 N/mm, and the joint efficiency was 70% with respect to the Mg alloy base metal.

  4. Thermal and hydraulic performance of compact brazed plate heat exchangers operating as evaporators in domestic heat pumps

    OpenAIRE

    Claesson, Joachim

    2005-01-01

    This thesis investigates the performance of compact brazed plate heat exchangers (CBE) operating as evaporator in heat pump applications. The thesis, and the performances investigated, has been divided into three main sections; One zone evaporator performance; Two zone evaporator performance; and finally Local performance. The 'One zone evaporator performance' section considers the evaporator as one "black box". It was found that "approaching terminal temperatures" were obtained as low overal...

  5. Design of Refractory Metal Life Test Heat Pipe and Calorimeter

    Science.gov (United States)

    Martin, J. J.; Reid, R. S.; Bragg-Sitton, S. M.

    2010-01-01

    Heat pipe life tests have seldom been conducted on a systematic basis. Typically, one or more heat pipes are built and tested for an extended period at a single temperature with simple condenser loading. Results are often reported describing the wall material, working fluid, test temperature, test duration, and occasionally the nature of any failure. Important information such as design details, processing procedures, material assay, power throughput, and radial power density are usually not mentioned. We propose to develop methods to generate carefully controlled data that conclusively establish heat pipe operating life with material-fluid combinations capable of extended operation. The test approach detailed in this Technical Publication will use 16 Mo-44.5%Re alloy/sodium heat pipe units that have an approximate12-in length and 5/8-in diameter. Two specific test series have been identified: (1) Long-term corrosion rates based on ASTM-G-68-80 (G-series) and (2) corrosion trends in a cross-correlation sequence at various temperatures and mass fluences based on a Fisher multifactor design (F-series). Evaluation of the heat pipe hardware will be performed in test chambers purged with an inert purified gas (helium or helium/argon mixture) at low pressure (10-100 torr) to provide thermal coupling between the heat pipe condenser and calorimeter. The final pressure will be selected to minimize the potential for voltage breakdown between the heat pipe and radio frequency (RF) induction coil (RF heating is currently the planned method of powering the heat pipes). The proposed calorimeter is constructed from a copper alloy and relies on a laminar flow water-coolant channel design to absorb and transport energy

  6. Office Procedures in Refractory Chronic Rhinosinusitis.

    Science.gov (United States)

    Thamboo, Andrew; Patel, Zara M

    2017-02-01

    Office procedures in chronic rhinosinusitis (CRS) can be considered before and after medical management, as well as before and after surgical management. This article focuses specifically on refractory CRS, meaning those patients who have failed medical and surgical management already. The options available in the management of refractory CRS depend on the personnel, equipment, and instrumentation available in the office setting; surgeon experience; and patient suitability and tolerability. This article provides readers with possible procedural options that can be done in their clinics with indications, patient selection, potential complications, and postoperative considerations. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Magnesite and chromium-magnesite refractories

    Energy Technology Data Exchange (ETDEWEB)

    Campos Loriz, D.

    1981-01-01

    The fifth part of the series, is concerned with a study on magnesite refractories, essential to the basic steelplant and starts with both traditional (natural carbonates and hydroxides) and recently-used (sea-water hydroxide) raw materials. Following a discussion on the fundamental system MgO-CaO-Si/sub 2/ consideration is given, among others, to baked, tarred and chemically-bonded refractories; their properties and use, ending with a brief examination of conventional and direct-bond chromium-magnesite materials.

  8. Double sequential defibrillation for refractory ventricular fibrillation.

    Science.gov (United States)

    El Tawil, Chady; Mrad, Sandra; Khishfe, Basem F

    2017-12-01

    A 54-year-old suffered from an out-of-hospital cardiac arrest. Compressions were started within minutes and the patient was in refractory ventricular fibrillation despite multiple asynchronized shocks and maximal doses of antiarrhythmic agents. Double sequential defibrillation was attempted with successful Return Of Spontaneous Circulation (ROSC) after a total of 61min of cardiac arrest. The patient was discharged home neurologically intact. Double sequential defibrillation could be a simple effective approach to patients with refractory ventricular fibrillation. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Reduced-Temperature Transient-Liquid-Phase Bonding of AluminaUsing a Ag-Cu-Based Brazing Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Moo; Glaeser, Andreas M.

    2005-12-19

    The mechanical properties and microstructural evolution ofmetal-ceramic bonds produced using a transient liquid phase (TLP) aredescribed. Alumina (Al2O3) was joined at 500 degrees C, 600 degrees C,and 700 degrees C using a multilayer In/Cusil-ABA (R) (commercialcopper-silver eutectic brazing alloy)/In interlayer. The introduction ofthin In cladding layers allows the system to bond at much lowertemperatures than those typically used for brazing with Cusil-ABA (R),thereby protecting temperature-sensitive components. After chemicalhomogenization, the interlayers retain an operating temperature rangesimilar to that of the brazed joints. TLP bonds made at 500 degrees C,600 degrees C, and 700 degrees C with holding times ranging from as lowas 1.5 h to 24 h had average fracture strengths above 220 MPa. Theeffects of bonding temperature and time on fracture strength aredescribed. Preliminary analysis of the interlayers shows that the Ag-Inor Cu-In intermetallic phases do not form. Considerations unique tosystems with two-phase core layers are discussed. Experiments usingsingle-crystal sapphire indicate rapid formation of a reaction layer at700 degrees C, suggesting the possibility of making strong bonds usinglower temperatures and/or shorter processing times.

  10. Preparation of W/CuCrZr mono-block test mock-up using vacuum brazing technique

    Science.gov (United States)

    Premjit Singh, K.; Khirwadkar, S.; Bhope, Kedar; Patel, Nikunj; Mokaria, Prakash

    2017-04-01

    Development of the joining for W/CuCrZr mono-block PFC test mock-up is an interesting area in Fusion R&D. W/Cu bimetallic material has been prepared using OFHC Copper casting approach on the radial surface of W mono-block tile surface. The W/Cu bimetallic material has been joined with CuCrZr tube (heat sink) material with the vacuum brazing route. Vacuum brazing of W/Cu-CuCrZr has been performed @ 970°C for 10 min using NiCuMn-37 filler material under deep vacuum environment (10-6 mbar). Graphite fixture was used for OFHC Copper casting and vacuum brazing experiments. The joint integrity of W/Cu-CuCrZr mono-block mock-up of W/Cu and Cu-CuCrZr interface has been checked using ultrasonic immersion technique. The result of the experimental work is presented in the paper.

  11. Two-beam Laser Brazing of Thin Sheet Steel for Automotive Industry Using Cu-base Filler Material

    Science.gov (United States)

    Mittelstädt, C.; Seefeld, T.; Reitemeyer, D.; Vollertsen, F.

    This work shows the potential of two-beam laser brazing for joining both Zn-coated steel and 22MnB5. Brazing of Zn-coated steel sheets using Cu-Si filler wire is already state of the art in car manufacturing. New press-hardened steels like 22MnB5 are more and more used in automotive industry, offering high potential to save costs and improve structural properties (reduced weight / higher stiffness). However, for joining of these ultra-high strength steels investigations are mandatory. In this paper, a novel approach using a two-beam laser brazing process and Cu-base filler material is presented. The use of Cu-base filler material leads to a reduced heat input, compared to currently applied welding processes, which may result in benefits concerning distortion, post processing and tensile strength of the joint. Reliable processing at desired high speeds is attained by means of laser-preheating. High feed rates prevent significant diffusion of copper into the base material.

  12. Refractory disease in antineutrophil cytoplasmic antibodies associated vasculitis

    NARCIS (Netherlands)

    Rutgers, Abraham; Kallenberg, Cornelis

    Purpose of review Induction treatment of antineutrophil cytoplasmic antibodies (ANCA) associated vasculitis (AAV) is not always successful and nonresponding patients are considered refractory. Recent findings Refractory disease should be subdefined to the treatment that was received.

  13. Characterization and testing of refractories for glass tank melters

    OpenAIRE

    Velez,M.; Karakus,M.; Reidmeyer,M. R.; Headrick,W. D.; Moore,R. E.

    2001-01-01

    Current and future research goals in our laboratories include the study of the attack of glass-contact refractories and of crown refractories in glass tank melters, under either air-gas or oxyfuel conditions. There is an emphasis on evaluation and characterization of critical parameters of commercial refractories such as microstructure, porosity and mechanical properties. A second focus is the evaluation of the performance of refractory alternatives to traditional crown and superstructure ref...

  14. Recent advances in silica-alumina refractory: A review

    OpenAIRE

    Sadik, Chaouki; El Amrani, Iz-Eddine; Albizane, Abderrahman

    2014-01-01

    In this article, the elaboration and the characterization of silica-alumina refractory have been reviewed. Refractory oxides encompass a broad range of unary, binary, and ternary ceramic compounds that can be used in structural, insulating, and other applications. This paper provides a historical perspective on the elaboration and the use of silica-alumina refractory, reviews applications for refractory oxides, describes typical processing routes, overviews fundamental structure–property rela...

  15. Recent advances in silica-alumina refractory: A review

    Directory of Open Access Journals (Sweden)

    Chaouki Sadik

    2014-06-01

    Full Text Available In this article, the elaboration and the characterization of silica-alumina refractory have been reviewed. Refractory oxides encompass a broad range of unary, binary, and ternary ceramic compounds that can be used in structural, insulating, and other applications. This paper provides a historical perspective on the elaboration and the use of silica-alumina refractory, reviews applications for refractory oxides, describes typical processing routes, overviews fundamental structure–property relations, and summarizes the properties of these materials.

  16. Iatrogenic colorectal Kaposi sarcoma complicating a refractory ...

    African Journals Online (AJOL)

    Kaposi sarcoma is a mesenchymal tumor associated to a human herpes virus-8. It often occurs in human immunodeficiency virus-positive subjects. Colorectal localization is rare. We report the case of a colorectal Kaposi sarcoma complicating a refractory ulcerative colitis treated with surgery after the failure of ...

  17. Emerging therapeutics in refractory renal cell carcinoma.

    Science.gov (United States)

    Koshkin, Vadim S; Rini, Brian I

    2016-06-01

    Metastatic renal cell carcinoma (mRCC) has seen the introduction of numerous new treatments over the past decade. However, the efficacy of these therapies has plateaued, and new treatment options are needed for the majority of patients with mRCC whose disease inevitably progresses through one or more standard therapies ('refractory' mRCC). Recently approved agents in this space have shown great promise. This article reviews the evidence behind current management strategies for mRCC. After reviewing clinical trials that established current first-line therapies and agents used in the refractory setting, we address new ideas for the treatment of refractory disease including combination therapies and novel targeted agents. In particular, we focus on targeted immunotherapy in refractory mRCC. We conclude by considering future directions in combination treatments utilizing these novel agents. Numerous approaches have produced tangible benefits for the treatment of patients with mRCC. These include development of next generation VEGFR/TKIs, targeted immunotherapy agents, and the development of combined regimens. In particular, immunotherapy agents targeting the PD1/PD-L1 pathway have shown great promise with a robust survival advantage seen in patients treated with nivolumab. A tolerable side effect profile of immunotherapy agents makes them amenable for use in combination therapies and ongoing trials are addressing this question.

  18. Materials design considerations involved in the fabrication of implantable bionics by metallization of ceramic substrates.

    Science.gov (United States)

    Patel, Sunil; Guenther, Thomas; Dodds, Christopher W D; Kolke, Sergej; Privat, Karen L; Matteucci, Paul B; Suaning, Gregg J

    2013-01-01

    The Pt metallization of co-fired Al2O3/SiO2 substrates containing Pt feedthroughs was shown to be a suitable means to construct implantable bionics. The use of forge welding to join an electrode to such a metallized feedthrough was demonstrated and subsequently evaluated through the use of metallography and electron microscopy. Metallurgical phenomena involved in forge welding relevant to the fabrication of all types of biomedical implants are discussed within this paper. The affect of thermal profiles used in brazing or welding to build implantable devices from metal components is analysed and the case for considered selection of alloys in implant design is put forward.

  19. Clinical Features of Refractory Ascites in Outpatients

    Directory of Open Access Journals (Sweden)

    Wanda Regina Caly

    Full Text Available OBJECTIVES: To present the clinical features and outcomes of outpatients who suffer from refractory ascites. METHODS: This prospective observational study consecutively enrolled patients with cirrhotic ascites who submitted to a clinical evaluation, a sodium restriction diet, biochemical blood tests, 24 hour urine tests and an ascitic fluid analysis. All patients received a multidisciplinary evaluation and diuretic treatment. Patients who did not respond to the diuretic treatment were controlled by therapeutic serial paracentesis, and a transjugular intrahepatic portosystemic shunt was indicated for patients who required therapeutic serial paracentesis up to twice a month. RESULTS: The most common etiology of cirrhosis in both groups was alcoholism [49 refractory (R and 11 non-refractory ascites (NR]. The majority of patients in the refractory group had Child-Pugh class B cirrhosis (p=0.034. The nutritional assessment showed protein-energy malnutrition in 81.6% of the patients in the R group and 35.5% of the patients in the NR group, while hepatic encephalopathy, hernia, spontaneous bacterial peritonitis, upper digestive hemorrhage and type 2 hepatorenal syndrome were present in 51%, 44.9%, 38.8%, 38.8% and 26.5% of the patients in the R group and 9.1%, 18.2%, 0%, 0% and 0% of the patients in the NR group, respectively (p=0.016, p=0.173, p=0.012, p=0.012, and p=0.100, respectively. Mortality occurred in 28.6% of the patients in the R group and in 9.1% of the patients in the NR group (p=0.262. CONCLUSION: Patients with refractory ascites were malnourished, suffered from hernias, had a high prevalence of complications and had a high postoperative death frequency, which was mostly due to infectious processes.

  20. Comprehensive Utilization of Iron and Phosphorus from High-Phosphorus Refractory Iron Ore

    Science.gov (United States)

    Sun, Yongsheng; Zhang, Qi; Han, Yuexin; Gao, Peng; Li, Guofeng

    2018-02-01

    An innovative process of coal-based reduction followed by magnetic separation and dephosphorization was developed to simultaneously recover iron and phosphorus from one typical high-phosphorus refractory iron ore. The experimental results showed that the iron minerals in iron ore were reduced to metallic iron during the coal-based reduction and the phosphorus was enriched in the metallic iron phase. The CaO-SiO2-FeO-Al2O3 slag system was used in the dephosphorization of metallic iron. A hot metal of 99.17% Fe and 0.10% P was produced with Fe recovery of 84.41%. Meanwhile, a dephosphorization slag of 5.72% P was obtained with P recovery of 67.23%. The contents of impurities in hot metal were very low, and it could be used as feedstock for steelmaking after a secondary refining. Phosphorus in the dephosphorization slag mainly existed in the form of a 5CaO·P2O5·SiO2 solid solution where the P2O5 content is 13.10%. At a slag particle size of 20.7 μm (90% passing), 94.54% of the P2O5 could be solubilized in citric acid, indicating the slag met the feedstock requirements in phosphate fertilizer production. Consequently, the proposed process achieved simultaneous Fe and P recovery, paving the way to comprehensive utilization of high-phosphorus refractory iron ore.