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Sample records for in-can melting process

  1. In-can melting process and equipment development from 1974 to 1978

    International Nuclear Information System (INIS)

    Blair, H.T.

    1979-08-01

    Both the defense HLLW stores in tanks presently and the HLLW from proposed reprocessing of commercial LWR fuel can be vitrified as borosilicate glass in containers made of 300-series stainless steel by the ICM (in-can melting) process. Melting rates of 50 kg/h in 12-in.-dia cans and 117 kg/h in 28-in.-dia cans can be achieved in the ICM by using the rising-level charging method and internal heat-transfer plate assemblies in the cans. The ICM process can be monitored and remotely controlled without the aid of instrumentation attached to the waste can. The ICM process is compatible with both heated-wall spray calciners and fluidized-bed calciners. The ICM process causes residual tensile stresses as high as the yield strength in vitrified product containers made of 300-series stainless steel. Spall due to oxidation of the exterior of the can during an ICM process can be prevented by using an inert cover gas, by putting a protective coating on the can surface, or by using an oxidation-resistant alloy. Processing problems are minimized and product quality is improved when the complete can is located inside the furnace chamber by setting it on the hearth. A maximum of 24 kW and an average of 15 kW is required per 15-in.-high furnace zone to melt waste borosilicate glass at a rate of 117 kg/h in a 28-in.-dia ICM

  2. In-can melting demonstration of wastes from the Idaho Chemical Processing Plant

    International Nuclear Information System (INIS)

    Bjorklund, W.J.; Chick, L.A.; Hollis, H.H.; Mellinger, G.B.; Nelson, T.A.; Petkus, L.L.

    1980-07-01

    The immobilization of Idaho Chemical Processing Plant (ICPP) zirconia calcine using Idaho glass composition (ICPP-127) was evaluated at Pacific Northwest Laboratory (PNL) in two engineering-scale in-can melter tests. The glass was initially characterized in the laboratory to verify processing parameters. Glass was then produced in a pilot-scale melter and then in a full-scale melter to evaluate the processing and the resultant product. Potential corrosion problems were identified with the glass and some processing problems were encountered, but neither is insurmountable. The product is a durable leach-resistant glass. The glass appears to be nonhomogeneous, but chemically it is quite uniform

  3. Monitoring of polymer melt processing

    International Nuclear Information System (INIS)

    Alig, Ingo; Steinhoff, Bernd; Lellinger, Dirk

    2010-01-01

    The paper reviews the state-of-the-art of in-line and on-line monitoring during polymer melt processing by compounding, extrusion and injection moulding. Different spectroscopic and scattering techniques as well as conductivity and viscosity measurements are reviewed and compared concerning their potential for different process applications. In addition to information on chemical composition and state of the process, the in situ detection of morphology, which is of specific interest for multiphase polymer systems such as polymer composites and polymer blends, is described in detail. For these systems, the product properties strongly depend on the phase or filler morphology created during processing. Examples for optical (UV/vis, NIR) and ultrasonic attenuation spectra recorded during extrusion are given, which were found to be sensitive to the chemical composition as well as to size and degree of dispersion of micro or nanofillers in the polymer matrix. By small-angle light scattering experiments, process-induced structures were detected in blends of incompatible polymers during compounding. Using conductivity measurements during extrusion, the influence of processing conditions on the electrical conductivity of polymer melts with conductive fillers (carbon black or carbon nanotubes) was monitored. (topical review)

  4. Melt processed high-temperature superconductors

    CERN Document Server

    1993-01-01

    The achievement of large critical currents is critical to the applications of high-temperature superconductors. Recent developments have shown that melt processing is suitable for producing high J c oxide superconductors. Using magnetic forces between such high J c oxide superconductors and magnets, a person could be levitated.This book has grown largely out of research works on melt processing of high-temperature superconductors conducted at ISTEC Superconductivity Research Laboratory. The chapters build on melt processing, microstructural characterization, fundamentals of flux pinning, criti

  5. Melt processing of polymer biocomposites

    Directory of Open Access Journals (Sweden)

    Juliana França Marinho

    2015-04-01

    Full Text Available A coupled device extruder and injection moulding were used to prepare biocomposites in order to provide a continuous and large-scale production, and overcome the fiber degradation inside the extruder. Two types of biocomposites were prepared, Sisal/poly(buthylene adipate-co-terephthlate – PBAT and Juta/poly(lactide acid/poly(buthylene adipate-co-terephthlate blend. The biocomposites were prepared with fiber as-received and alkaline treated. The mechanical properties of biocomposites were increased by the fibers content; and the alkaline treatment was efficient to promote a good adhesion between fiber and polymer. In the case of the Juta fiber, the alkaline treatment used was too strong and led to fiber degradation. The results presented here show an alternative and continuous process to obtain biocomposites with relevant mechanical properties using fiber roving and avoiding fiber degradation.

  6. Melt processing of Yb-123 tapes

    International Nuclear Information System (INIS)

    Athur, S. P.; Balachandran, U.; Salama, K.

    2000-01-01

    The innovation of a simple, scalable process for manufacturing long-length conductors of HTS is essential to potential commercial applications such as power cables, magnets, and transformers. In this paper the authors demonstrate that melt processing of Yb-123 tapes made by the PIT route is an alternative to the coated conductor and Bi-2223 PIT tape fabrication techniques. Ag-clad Yb-123 tapes were fabricated by groove rolling and subsequently, melt processed in different oxygen partial pressures in a zone-melting furnace with a gradient of 140 C/cm. The transition temperatures measured were found to be around 81 K undermost processing conditions. EPMA of the tapes processed under different conditions show the 123 phase to be Ba deficient and Cu and Yb rich. Critical current was measured at various temperatures from 77 K to 4.2 K. The J c increased with decrease in pO 2 . The highest I c obtained was 52 A at 4.2 K

  7. Polymer-organoclay nanocomposites by melt processing

    Science.gov (United States)

    Cui, Lili

    2009-12-01

    Polymer-layered silicate nanocomposites based on a variety of polymer matrices and several organoclays were prepared by melt processing. A detailed characterization of the thermal degradation of several commercial and experimental organoclays often used to form polymer nanocomposites was reported. The surfactant type, loading, and purification level of organoclay significantly affect their thermal stability; however, broadly speaking, the results suggest that these differences in thermal stability do not appear to have much effect on the morphology and properties of the nanocomposites formed from them. It seems that the thermal stability of organoclays is not the key factor in organoclay exfoliation in melt processed polymer nanocomposites, since the exfoliation/dispersion process may have been completed on a time scale before the degradation of surfactant progresses to a detrimental level. Polymer nanocomposites have been made from a variety of polymers; however, few matrices have demonstrated the ability to readily exfoliate the organoclay as well as nylon 6, especially for highly hydrophobic materials like polyolefins. Hence, a significant part of this research work was devoted to explore various routes to improve polyolefin-organoclay interactions, and thus, organoclay exfoliation in these systems. Amine grafted polypropylenes and a conventionally used maleic anhydride grafted polypropylene were used as compatibilizers for polypropylene based nanocomposites to improve the organoclay exfoliation. A series of ethylene vinyl acetate copolymers, the polarity of which can be adjusted by varying their vinyl acetate contents, based nanocomposites were prepared as the model system to address the relationship between the polarity of the polymers and their preferences over various organoclay structures. Attempts were made to explore the effect of degree of neutralization of acid groups in ionomers on the morphology and properties of nanocomposites, and it seems that the

  8. A multi-component evaporation model for beam melting processes

    Science.gov (United States)

    Klassen, Alexander; Forster, Vera E.; Körner, Carolin

    2017-02-01

    In additive manufacturing using laser or electron beam melting technologies, evaporation losses and changes in chemical composition are known issues when processing alloys with volatile elements. In this paper, a recently described numerical model based on a two-dimensional free surface lattice Boltzmann method is further developed to incorporate the effects of multi-component evaporation. The model takes into account the local melt pool composition during heating and fusion of metal powder. For validation, the titanium alloy Ti-6Al-4V is melted by selective electron beam melting and analysed using mass loss measurements and high-resolution microprobe imaging. Numerically determined evaporation losses and spatial distributions of aluminium compare well with experimental data. Predictions of the melt pool formation in bulk samples provide insight into the competition between the loss of volatile alloying elements from the irradiated surface and their advective redistribution within the molten region.

  9. Numerical Model based Reliability Estimation of Selective Laser Melting Process

    DEFF Research Database (Denmark)

    Mohanty, Sankhya; Hattel, Jesper Henri

    2014-01-01

    Selective laser melting is developing into a standard manufacturing technology with applications in various sectors. However, the process is still far from being at par with conventional processes such as welding and casting, the primary reason of which is the unreliability of the process. While...... of the selective laser melting process. A validated 3D finite-volume alternating-direction-implicit numerical technique is used to model the selective laser melting process, and is calibrated against results from single track formation experiments. Correlation coefficients are determined for process input...... parameters such as laser power, speed, beam profile, etc. Subsequently, uncertainties in the processing parameters are utilized to predict a range for the various outputs, using a Monte Carlo method based uncertainty analysis methodology, and the reliability of the process is established....

  10. Energy asymmetry in melting and solidifying processes of PCM

    International Nuclear Information System (INIS)

    Jin, Xing; Hu, Huoyan; Shi, Xing; Zhang, Xiaosong

    2015-01-01

    Highlights: • The melting process and the solidifying process of PCM were asymmetrical. • The enthalpy and state of PCM were affected by its previous state. • The main reason for energy asymmetry of PCM was supercooling. - Abstract: The solidifying process of phase change material (PCM) was usually recognized as the exact inverse process of its melting process, especially when building the heat transfer model of PCM. To figure out that whether the melting process and the solidifying process of PCM were symmetrical, several kinds of PCMs were tested by a differential scanning calorimeter (DSC) in this paper. The experimental results showed that no matter using the DSC dynamic measurement method or the DSC step measurement method, the melting process and the solidifying process of PCM were asymmetrical. Because of the energy asymmetry in the melting and solidifying processes of PCM, it was also found that the enthalpy and the state of PCM were not only dependent on its temperature, but also affected by its “previous state”.

  11. Research of Snow-Melt Process on a Heated Platform

    Directory of Open Access Journals (Sweden)

    Vasilyev Gregory P.

    2016-01-01

    Full Text Available The article has shown the results of experimental researches of the snow-melt on a heated platform-near building heat-pump snow-melt platform. The near-building (yard heat pump platforms for snow melt with the area up to 10-15 m2 are a basis of the new ideology of organization of the street cleaning of Moscow from snow in the winter period which supposes the creation in the megalopolis of the «distributed snow-melt system» (DSMS using non-traditional energy sources. The results of natural experimental researches are presented for the estimation of efficiency of application in the climatic conditions of Moscow of heat pumps in the snow-melt systems. The researches were conducted on a model sample of the near-building heat-pump platform which uses the low-potential thermal energy of atmospheric air. The conducted researches have confirmed experimentally in the natural conditions the possibility and efficiency of using of atmospheric air as a source of low-potential thermal energy for evaporation of the snow-melt heat pump systems in the climatic conditions of Moscow. The results of laboratory researches of snow-melt process on a heated horizontal platform are presented. The researches have revealed a considerable dependence of efficiency of the snow-melt process on its piling mode (form-building and the organization of the process of its piling mode (form-building and the organization of the process of its (snow mass heat exchange with the surface of the heated platform. In the process of researches the effect of formation of an «ice dome» under the melting snow mass called by the fact that in case of the thickness of snow loaded on the platform more than 10 cm the water formed from the melting snow while the contact with the heating surface don’t spread on it, but soaks into the snow, wets it due to capillary effect and freezes. The formation of «ice dome» leads to a sharp increase of snow-melt period and decreases the operating

  12. Additive Manufacturing Processes: Selective Laser Melting, Electron Beam Melting and Binder Jetting-Selection Guidelines.

    Science.gov (United States)

    Gokuldoss, Prashanth Konda; Kolla, Sri; Eckert, Jürgen

    2017-06-19

    Additive manufacturing (AM), also known as 3D printing or rapid prototyping, is gaining increasing attention due to its ability to produce parts with added functionality and increased complexities in geometrical design, on top of the fact that it is theoretically possible to produce any shape without limitations. However, most of the research on additive manufacturing techniques are focused on the development of materials/process parameters/products design with different additive manufacturing processes such as selective laser melting, electron beam melting, or binder jetting. However, we do not have any guidelines that discuss the selection of the most suitable additive manufacturing process, depending on the material to be processed, the complexity of the parts to be produced, or the design considerations. Considering the very fact that no reports deal with this process selection, the present manuscript aims to discuss the different selection criteria that are to be considered, in order to select the best AM process (binder jetting/selective laser melting/electron beam melting) for fabricating a specific component with a defined set of material properties.

  13. Additive Manufacturing Processes: Selective Laser Melting, Electron Beam Melting and Binder Jetting—Selection Guidelines

    Science.gov (United States)

    Konda Gokuldoss, Prashanth; Kolla, Sri; Eckert, Jürgen

    2017-01-01

    Additive manufacturing (AM), also known as 3D printing or rapid prototyping, is gaining increasing attention due to its ability to produce parts with added functionality and increased complexities in geometrical design, on top of the fact that it is theoretically possible to produce any shape without limitations. However, most of the research on additive manufacturing techniques are focused on the development of materials/process parameters/products design with different additive manufacturing processes such as selective laser melting, electron beam melting, or binder jetting. However, we do not have any guidelines that discuss the selection of the most suitable additive manufacturing process, depending on the material to be processed, the complexity of the parts to be produced, or the design considerations. Considering the very fact that no reports deal with this process selection, the present manuscript aims to discuss the different selection criteria that are to be considered, in order to select the best AM process (binder jetting/selective laser melting/electron beam melting) for fabricating a specific component with a defined set of material properties. PMID:28773031

  14. Residence time modeling of hot melt extrusion processes.

    Science.gov (United States)

    Reitz, Elena; Podhaisky, Helmut; Ely, David; Thommes, Markus

    2013-11-01

    The hot melt extrusion process is a widespread technique to mix viscous melts. The residence time of material in the process frequently determines the product properties. An experimental setup and a corresponding mathematical model were developed to evaluate residence time and residence time distribution in twin screw extrusion processes. The extrusion process was modeled as the convolution of a mass transport process described by a Gaussian probability function, and a mixing process represented by an exponential function. The residence time of the extrusion process was determined by introducing a tracer at the extruder inlet and measuring the tracer concentration at the die. These concentrations were fitted to the residence time model, and an adequate correlation was found. Different parameters were derived to characterize the extrusion process including the dead time, the apparent mixing volume, and a transport related axial mixing. A 2(3) design of experiments was performed to evaluate the effect of powder feed rate, screw speed, and melt viscosity of the material on the residence time. All three parameters affect the residence time of material in the extruder. In conclusion, a residence time model was developed to interpret experimental data and to get insights into the hot melt extrusion process. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Stability of inflation processes with polymer melts

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Eriksson, Torbjörn Gerhard; Hassager, Ole

    2002-01-01

    The production process Blow-moulding is used to produce different kinds of bottles in plastic. The final stage in this process is the inflation of some kind of (extruded or injection moulded) cylinder outward against the wall of the mould. This creates the final shape of the product. The inflation...... is performed applying a gas pressure into the core of the cylinder, which press the molten plastic cylinder outward. During the inflation the plastic may burst. The occurrence of this burst, or break, puts a limit on the possibility to produce a specified product at some, or all, processing conditions. Here...

  16. Fundamental studies on cavitation melt processing

    Science.gov (United States)

    Tzanakis, I.; Hodnett, M.; Lebon, G. S. B.; Eskin, D. G.; Pericleous, K.

    2016-05-01

    The application of ultrasound to industrial casting processes has attracted research interest during the last 50 years. However, the transfer and scale-up of this advanced and promising technology to industry has been hindered by difficulties in treating large volumes of liquid metal due to the lack of understanding of certain fundamentals. In the current study experimental results on ultrasonic processing in deionised water and in liquid aluminium (Al) are reported. Cavitation activity was determined in both liquid environments and acoustic pressures were successfully measured using an advanced high-temperature cavitometer sensor. Results showed that highest cavitation intensity in the liquid bulk is achieved at lower amplitudes of the sonotrode tip than the maximum available, suggesting nonlinearity in energy transfer to the liquid, while the location of the sonotrode is seen to substantially affect cavitation activity within the liquid. Estimation of real-time acoustic pressures distributed inside a crucible with liquid Al was performed for the first time.

  17. Melting process by means of the hollow electrode melting system. Einschmelzverfahren mit dem Hohlelektroden-Schmelzsystem

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, F. (Mannesmann Anlagenbau AG, Duesseldorf (Germany)); Schubert, J. (Mannesmann Anlagenbau AG, Duesseldorf (Germany)); Staeubner, H. (Mannesmann Demag AG, Duisburg (Germany)); Lembgen, E. (Mannesmann Demag AG, Duisburg (Germany))

    1994-10-01

    It is shown that the proven hollow electrode melting system permits conversion of flue ash from waste incineration plants to reusable materials in full complience with the legal regulations, thus providing its recirculation as a raw or final product in the materials flow. This not only reduces the disposal of toxic substances, i.e., counteracts the practice of putting off problems, but also permits the recovery of a large fraction of the reusable materials. Moreover, it helps conserve resources. The glass-like product of this process is similar in composition to natural products and environmentally neutral. The process also provides a sink for toxic substances such as dioxins, which otherwise persist beyond disposal. The specific costs of a complete plant with all the necessary components for melting and cleaning systems are low. (orig./EF)

  18. Fundamental Aspects of Selective Melting Additive Manufacturing Processes

    Energy Technology Data Exchange (ETDEWEB)

    van Swol, Frank B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Miller, James E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-12-01

    Certain details of the additive manufacturing process known as selective laser melting (SLM) affect the performance of the final metal part. To unleash the full potential of SLM it is crucial that the process engineer in the field receives guidance about how to select values for a multitude of process variables employed in the building process. These include, for example, the type of powder (e.g., size distribution, shape, type of alloy), orientation of the build axis, the beam scan rate, the beam power density, the scan pattern and scan rate. The science-based selection of these settings con- stitutes an intrinsically challenging multi-physics problem involving heating and melting a metal alloy, reactive, dynamic wetting followed by re-solidification. In addition, inherent to the process is its considerable variability that stems from the powder packing. Each time a limited number of powder particles are placed, the stacking is intrinsically different from the previous, possessing a different geometry, and having a different set of contact areas with the surrounding particles. As a result, even if all other process parameters (scan rate, etc) are exactly the same, the shape and contact geometry and area of the final melt pool will be unique to that particular configuration. This report identifies the most important issues facing SLM, discusses the fundamental physics associated with it and points out how modeling can support the additive manufacturing efforts.

  19. DU Processing Efficiency and Reclamation: Plasma Arc Melting

    Energy Technology Data Exchange (ETDEWEB)

    Imhoff, Seth D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aikin, Jr., Robert M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Swenson, Hunter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Solis, Eunice Martinez [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-26

    The work described here corresponds to one piece of a larger effort to increase material usage efficiency during DU processing operations. In order to achieve this goal, multiple technologies and approaches are being tested. These technologies occupy a spectrum of technology readiness levels (TRLs). Plasma arc melting (PAM) is one of the technologies being investigated. PAM utilizes a high temperature plasma to melt materials. Depending on process conditions, there are potential opportunities for recycling and material reclamation. When last routinely operational, the LANL research PAM showed extremely promising results for recycling and reclamation of DU and DU alloys. The current TRL is lower due to machine idleness for nearly two decades, which has proved difficult to restart. This report describes the existing results, promising techniques, and the process of bringing this technology back to readiness at LANL.

  20. Effects of Melt Processing on Evolution of Structure in PEEK

    Science.gov (United States)

    Georgiev, Georgi; Dai, Patrick Shuanghua; Oyebode, Elizabeth; Cebe, Peggy; Capel, Malcolm

    1999-01-01

    We report on the effects of melt processing temperature on structure formation in Poly(ether-ether-ketone), PEEK. Real time Small Angle X-ray Scattering, SAXS, and thermal analysis are used to follow the melting behavior after various stages of processing. Assignment of peaks to structural entities within the material, the relative perfection of the crystals, and the possibility of their reorganization, are all influenced by the melt processing history. With the advent of high intensity synchrotron sources of X-radiation, polymer scientists gain a research tool which, when used along with thermal analysis, provides additional structural information about the crystals during growth and subsequent melting. PEEK is an engineering thermoplastic polymer with a very high glass transition temperature (145 C) and crystal melting point (337 C). PEEK has been the subject of recent studies by X-ray scattering in which melt and cold crystallization were followed in real-time. X-ray scattering and thermal studies have been used to address the formation of dual endothermic response which has been variously ascribed to lamellar insertion, dual crystal populations, or melting followed by re-crystallization. Another important issue is whether all of the amorphous phase is located in interlamellar regions, or alternatively whether some is located in "pockets" away from the crystalline lamellar stacks. The interpretation of scattering from lamellar stacks varies depending upon whether such amorphous pockets are formed. Some groups believe all of the amorphous phase is interlamellar. This leads to selection of a smaller thickness for the crystals. Other groups suggest that most amorphous phase is not interlamellar, and this leads to the suggestion that the crystal thickness is larger than the amorphous layer within the stacks. To investigate these ideas, we used SAXS and Differential Scanning Calorimetry to compare results of single and dual stage melt crystallization of PEEK using a

  1. Recycling melting process of the zirconium alloy chips

    International Nuclear Information System (INIS)

    Reis, Luis A.M. dos; Mucsi, Cristiano S.; Tavares, Luiz A.P.; Alencar, Maicon C.; Gomes, Maurilio P.; Barbosa, Luzinete P.; Rossi, Jesualdo L.

    2017-01-01

    Pressurized water reactors (PWR) commonly use 235 U enriched uranium dioxide pellets as a nuclear fuel, these are assembled and stacked in zirconium alloy tubes and end caps (M5, Zirlo, Zircaloy). During the machining of these components large amounts of chips are generated which are contaminated with cutting fluid. Its storage presents safety and environmental risks due to its pyrophoric and reactive nature. Recycling industry shown interest in its recycling due to its strategic importance. This paper presents a study on the recycling process and the results aiming the efficiency in the cleaning process; the quality control; the obtaining of the pressed electrodes and finally the melting in a Vacuum Arc Remelting furnace (VAR). The recycling process begins with magnetic separation of possible ferrous alloys chips contaminant, the washing of the cutting fluid that is soluble in water, washing with an industrial degreaser, followed by a rinse with continuous flow of water under high pressure and drying with hot air. The first evaluation of the process was done by an Energy Dispersive X-rays Fluorescence Spectrometry (EDXRFS) showed the presence of 10 wt. % to 17 wt. % of impurities due the mixing with stainless steel machining chips. The chips were then pressed in a custom-made matrix of square section (40 x 40 mm - 500 mm in length), resulting in electrodes with 20% of apparent density of the original alloy. The electrode was then melted in a laboratory scale VAR furnace at the CCTM-IPEN, producing a massive ingot with 0.8 kg. It was observed that the samples obtained from Indústrias Nucleares do Brasil (INB) are supposed to be secondary scrap and it is suggested careful separation in the generation of this material. The melting of the chips is possible and feasible in a VAR furnace which reduces the storage volume by up to 40 times of this material, however, it is necessary to correct the composition of the alloy for the melting of these ingots. (author)

  2. NANOSTRUCTURAL PROCESSES OF MELTING AND MOULDING OF HYPOEUTECTIC SILUMIN

    Directory of Open Access Journals (Sweden)

    V. Yu. Stetsenko

    2016-01-01

    Full Text Available It is shown that melting and molding of hypoeutectic silumin are difficult physical and chemical nanostructural processes. In them the major role is played by the centers of crystallization of primary dendrites of aluminum, aluminum nanocrystals, the dissolved and adsorbed hydrogen. The role of the modifying crystals of an intermetallid of TiAl3 is reduced to absorption of the dissolved hydrogen and an intensification of process of a koalestsention of nanocrystals of aluminum in the centers of crystallization of primary dendrites of aluminum.

  3. Methodology of Fault Diagnosis in Ductile Iron Melting Process

    Directory of Open Access Journals (Sweden)

    Perzyk M.

    2016-12-01

    Full Text Available Statistical Process Control (SPC based on the Shewhart’s type control charts, is widely used in contemporary manufacturing industry, including many foundries. The main steps include process monitoring, detection the out-of-control signals, identification and removal of their causes. Finding the root causes of the process faults is often a difficult task and can be supported by various tools, including data-driven mathematical models. In the present paper a novel approach to statistical control of ductile iron melting process is proposed. It is aimed at development of methodologies suitable for effective finding the causes of the out-of-control signals in the process outputs, defined as ultimate tensile strength (Rm and elongation (A5, based mainly on chemical composition of the alloy. The methodologies are tested and presented using several real foundry data sets. First, correlations between standard abnormal output patterns (i.e. out-of-control signals and corresponding inputs patterns are found, basing on the detection of similar patterns and similar shapes of the run charts of the chemical elements contents. It was found that in a significant number of cases there was no clear indication of the correlation, which can be attributed either to the complex, simultaneous action of several chemical elements or to the causes related to other process variables, including melting, inoculation, spheroidization and pouring parameters as well as the human errors. A conception of the methodology based on simulation of the process using advanced input - output regression modelling is presented. The preliminary tests have showed that it can be a useful tool in the process control and is worth further development. The results obtained in the present study may not only be applied to the ductile iron process but they can be also utilized in statistical quality control of a wide range of different discrete processes.

  4. Micropatterning of a Bipolar Plate Using Direct Laser Melting Process

    Science.gov (United States)

    Jang, Jeong-hwan; Joo, Byeong-don; Mun, Sung-min; Moona, Young-hoon

    2010-06-01

    Direct laser melting (DLM) technology has been used to fabricate the micro-pattern of the bipolar plate in a direct methanol fuel cell (DMFC). A suitable approach to enhance the performance of the bipolar plate has been performed to optimize the DLM process. To fabricate the micro pattern, a DLM process with 316L stainless steel powder has been used. For the melted height of 1 mm, the DLM process conditions were optimized such as; laser power of 200 W, scan rate of 36.62 mm/s and the 8-layer structures. To characterize the effect of material type, the bipolar plates of various types were analyzed. In case of the 316L stainless steel DLM patterning, a current density of 297 mA/cm2 was achieved but the case of the 316L stainless steel plate, 248 mA/cm2 current density that is lower than that of other materials was achieved. The overall cell performance of 316L stainless steel DLM patterning bipolar plate was better than that of the 316L stainless steel plate. This has significant advantages for the micropatterning using DLM process. The use of 316L stainless steel powder material as micro pattern material will reduce the machining cost as well as volume of the fuel cell stack.

  5. Thermal Modeling of Direct Digital Melt-Deposition Processes

    Science.gov (United States)

    Cooper, K. P.; Lambrakos, S. G.

    2011-02-01

    Additive manufacturing involves creating three-dimensional (3D) objects by depositing materials layer-by-layer. The freeform nature of the method permits the production of components with complex geometry. Deposition processes provide one more capability, which is the addition of multiple materials in a discrete manner to create "heterogeneous" objects with locally controlled composition and microstructure. The result is direct digital manufacturing (DDM) by which dissimilar materials are added voxel-by-voxel (a voxel is volumetric pixel) following a predetermined tool-path. A typical example is functionally gradient material such as a gear with a tough core and a wear-resistant surface. The inherent complexity of DDM processes is such that process modeling based on direct physics-based theory is difficult, especially due to a lack of temperature-dependent thermophysical properties and particularly when dealing with melt-deposition processes. In order to overcome this difficulty, an inverse problem approach is proposed for the development of thermal models that can represent multi-material, direct digital melt deposition. This approach is based on the construction of a numerical-algorithmic framework for modeling anisotropic diffusivity such as that which would occur during energy deposition within a heterogeneous workpiece. This framework consists of path-weighted integral formulations of heat diffusion according to spatial variations in material composition and requires consideration of parameter sensitivity issues.

  6. Recycling melting process of the zirconium alloy chips

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Luis A.M. dos; Mucsi, Cristiano S.; Tavares, Luiz A.P.; Alencar, Maicon C.; Gomes, Maurilio P.; Barbosa, Luzinete P.; Rossi, Jesualdo L., E-mail: luisreis.09@gmail.com, E-mail: csmucsi@gmail.com [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

    2017-07-01

    Pressurized water reactors (PWR) commonly use {sup 235}U enriched uranium dioxide pellets as a nuclear fuel, these are assembled and stacked in zirconium alloy tubes and end caps (M5, Zirlo, Zircaloy). During the machining of these components large amounts of chips are generated which are contaminated with cutting fluid. Its storage presents safety and environmental risks due to its pyrophoric and reactive nature. Recycling industry shown interest in its recycling due to its strategic importance. This paper presents a study on the recycling process and the results aiming the efficiency in the cleaning process; the quality control; the obtaining of the pressed electrodes and finally the melting in a Vacuum Arc Remelting furnace (VAR). The recycling process begins with magnetic separation of possible ferrous alloys chips contaminant, the washing of the cutting fluid that is soluble in water, washing with an industrial degreaser, followed by a rinse with continuous flow of water under high pressure and drying with hot air. The first evaluation of the process was done by an Energy Dispersive X-rays Fluorescence Spectrometry (EDXRFS) showed the presence of 10 wt. % to 17 wt. % of impurities due the mixing with stainless steel machining chips. The chips were then pressed in a custom-made matrix of square section (40 x 40 mm - 500 mm in length), resulting in electrodes with 20% of apparent density of the original alloy. The electrode was then melted in a laboratory scale VAR furnace at the CCTM-IPEN, producing a massive ingot with 0.8 kg. It was observed that the samples obtained from Indústrias Nucleares do Brasil (INB) are supposed to be secondary scrap and it is suggested careful separation in the generation of this material. The melting of the chips is possible and feasible in a VAR furnace which reduces the storage volume by up to 40 times of this material, however, it is necessary to correct the composition of the alloy for the melting of these ingots. (author)

  7. Connecting section and associated systems concept for the spray calciner/in-can melter process

    International Nuclear Information System (INIS)

    Petkus, L.L.; Gorton, P.S.; Blair, H.T.

    1981-06-01

    For a number of years, researchers at the Pacific Northwest Laboratory have been developing processes and equipment for converting high-level liquid wastes to solid forms. One of these processes is the Spray Calciner/In-Can Melter system. To immobilize high-level liquid wastes, this system must be operated remotely, and the calcine must be reliably conveyed from the calciner to the melting furnace. A concept for such a remote conveyance system was developed at the Pacific Northwest Laboratory, and equipment was tested under full-scale, nonradioactive conditions. This concept and the design of demonstration equipment are described, and the results of equipment operation during experimental runs of 7 d are presented. The design includes a connecting section and its associated systems - a canister sypport and alignment concept and a weight-monitoring system for the melting furnace. Overall, the runs demonstrated that the concept design is an acceptable method of connecting the two pieces of process equipment together. Although the connecting section has not been optimized in all areas of concern, it provides a first-generation design of a production-oriented system

  8. A slow atomic diffusion process in high-entropy glass-forming metallic melts

    Science.gov (United States)

    Chen, Changjiu; Wong, Kaikin; Krishnan, Rithin P.; Embs, Jan P.; Chathoth, Suresh M.

    2018-04-01

    Quasi-elastic neutron scattering has been used to study atomic relaxation processes in high-entropy glass-forming metallic melts with different glass-forming ability (GFA). The momentum transfer dependence of mean relaxation time shows a highly collective atomic transport process in the alloy melts with the highest and lowest GFA. However, a jump diffusion process is the long-range atomic transport process in the intermediate GFA alloy melt. Nevertheless, atomic mobility close to the melting temperature of these alloy melts is quite similar, and the temperature dependence of the diffusion coefficient exhibits a non-Arrhenius behavior. The atomic mobility in these high-entropy melts is much slower than that of the best glass-forming melts at their respective melting temperatures.

  9. Modern electrochemical processes and technologies in ionic melts

    Directory of Open Access Journals (Sweden)

    Omelchuk A.

    2003-01-01

    Full Text Available An analysis of the known methods for the electrochemical purification of non-ferrous metals in ionic melts is presented. A comparative estimation of the results of the electrochemical purification of non-ferrous metals by different methods has been performed. The main regularities of the electrochemical behavior of non-ferrous metals in conventional and electrode micro-spacing electrolysis are presented. It has been found that when electrolyzing some metals, e. g. bismuth, gallium, there is either no mass exchange between the electrodes, or it occurs under filtration conditions. It has been shown that the electrode micro-spacing processes provide a high quality of non-ferrous metals purification at low specific consumption of electric power and reagents. The use of bipolar electrodes and β-alumina diaphragms hinders the transfer of metallic impurities from the anode to the cathode. The effects revealed were used to develop new processes for the separation of non-ferrous metal alloys in ionic melts; most of them have been put into practice in non-ferrous metallurgy.

  10. Numerical simulation of hot-melt extrusion processes for amorphous solid dispersions using model-based melt viscosity.

    Science.gov (United States)

    Bochmann, Esther S; Steffens, Kristina E; Gryczke, Andreas; Wagner, Karl G

    2018-03-01

    Simulation of HME processes is a valuable tool for increased process understanding and ease of scale-up. However, the experimental determination of all required input parameters is tedious, namely the melt rheology of the amorphous solid dispersion (ASD) in question. Hence, a procedure to simplify the application of hot-melt extrusion (HME) simulation for forming amorphous solid dispersions (ASD) is presented. The commercial 1D simulation software Ludovic ® was used to conduct (i) simulations using a full experimental data set of all input variables including melt rheology and (ii) simulations using model-based melt viscosity data based on the ASDs glass transition and the physical properties of polymeric matrix only. Both types of HME computation were further compared to experimental HME results. Variation in physical properties (e.g. heat capacity, density) and several process characteristics of HME (residence time distribution, energy consumption) among the simulations and experiments were evaluated. The model-based melt viscosity was calculated by using the glass transition temperature (T g ) of the investigated blend and the melt viscosity of the polymeric matrix by means of a T g -viscosity correlation. The results of measured melt viscosity and model-based melt viscosity were similar with only few exceptions, leading to similar HME simulation outcomes. At the end, the experimental effort prior to HME simulation could be minimized and the procedure enables a good starting point for rational development of ASDs by means of HME. As model excipients, Vinylpyrrolidone-vinyl acetate copolymer (COP) in combination with various APIs (carbamazepine, dipyridamole, indomethacin, and ibuprofen) or polyethylene glycol (PEG 1500) as plasticizer were used to form the ASDs. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Impregnation of a glass fibre roving with a polypropylene melt in a pin assisted process

    NARCIS (Netherlands)

    Gaymans, R.J.; Wevers, E.

    1998-01-01

    The impregnation of a glass fibre bundle with a polypropylene (PP) melt is studied with a pin assisted process. A fibre is pulled over a pin, which is positioned in a chamber filled with a melt. The melt is at atmospheric pressure. The impregnation rate is studied as a function of size of the pin,

  12. Optimization of the melting process of electrical furnaces in drenas

    Directory of Open Access Journals (Sweden)

    A. Haxhiaj

    2012-10-01

    Full Text Available The weight, composition and loads are the main parameters of the melting process in electrical furnace. The charge is roasted in rotary furnace. Roasting of charge which consists of Drenas and Albanians ore is done at about 950°C. Also, article has the experimental analyses that modify some parameters of the production which are the reduction of quantity of limestone and the increase of quantity of quartz in the charge. The paper analysis the possibility of mixing the ore from Kosova with lateritic ore from Albania with the aim of reducing the acidity of weight which is loaded in the electrical furnace. The composition of the furnace must satisfy the ratio 1:10 of ore from Kosova and Albania.

  13. Applications of nonequilibrium melting concept to damage-accumulation processes

    International Nuclear Information System (INIS)

    Lam, N.Q.; Okamoto, P.R.

    1998-01-01

    The authors recent study of crystalline-to-amorphous transformation led to the successful development of a unified thermodynamic description of disorder-induced amorphization and heat-induced melting, based on a generalized version of the Lindemann melting criterion. The generalized criterion requires that the melting temperature of a defective crystal decreases with increasing static atomic disorder. Hence, any crystal can melt at temperatures below the melting point of its perfect crystalline state when driven far from equilibrium by introducing critical amounts of misfitting solute atoms and lattice imperfections, radiation damage, and/or tensile stresses. This conceptual approach to nonequilibrium melting provides new insight into long-standing materials problems such as brittle fracture, embrittlement, and environmentally-induced cracking, for example irradiation-assisted stress corrosion cracking

  14. Applications of nonequilibrium melting concept to damage-accumulation processes

    Energy Technology Data Exchange (ETDEWEB)

    Lam, N.Q.; Okamoto, P.R.

    1998-01-01

    The authors recent study of crystalline-to-amorphous transformation led to the successful development of a unified thermodynamic description of disorder-induced amorphization and heat-induced melting, based on a generalized version of the Lindemann melting criterion. The generalized criterion requires that the melting temperature of a defective crystal decreases with increasing static atomic disorder. Hence, any crystal can melt at temperatures below the melting point of its perfect crystalline state when driven far from equilibrium by introducing critical amounts of misfitting solute atoms and lattice imperfections, radiation damage, and/or tensile stresses. This conceptual approach to nonequilibrium melting provides new insight into long-standing materials problems such as brittle fracture, embrittlement, and environmentally-induced cracking, for example irradiation-assisted stress corrosion cracking.

  15. Evaluation of feeds for melt and dilute process using an analytical hierarchy process

    International Nuclear Information System (INIS)

    Krupa, J.F.

    2000-01-01

    Westinghouse Savannah River Company was requested to evaluate whether nuclear materials other than aluminum-clad spent nuclear fuel should be considered for treatment to prepare them for disposal in the melt and dilute facility as part of the Treatment and Storage Facility currently projected for construction in the L-Reactor process area. The decision analysis process used to develop this analysis considered many variables and uncertainties, including repository requirements that are not yet finalized. The Analytical Hierarchy Process using a ratings methodology was used to rank potential feed candidates for disposition through the Melt and Dilute facility proposed for disposition of Savannah River Site aluminum-clad spent nuclear fuel. Because of the scoping nature of this analysis, the expert team convened for this purpose concentrated on technical feasibility and potential cost impacts associated with using melt and dilute versus the current disposition option. This report documents results of the decision analysis

  16. Evaluation of feeds for melt and dilute process using an analytical hierarchy process

    Energy Technology Data Exchange (ETDEWEB)

    Krupa, J.F.

    2000-03-22

    Westinghouse Savannah River Company was requested to evaluate whether nuclear materials other than aluminum-clad spent nuclear fuel should be considered for treatment to prepare them for disposal in the melt and dilute facility as part of the Treatment and Storage Facility currently projected for construction in the L-Reactor process area. The decision analysis process used to develop this analysis considered many variables and uncertainties, including repository requirements that are not yet finalized. The Analytical Hierarchy Process using a ratings methodology was used to rank potential feed candidates for disposition through the Melt and Dilute facility proposed for disposition of Savannah River Site aluminum-clad spent nuclear fuel. Because of the scoping nature of this analysis, the expert team convened for this purpose concentrated on technical feasibility and potential cost impacts associated with using melt and dilute versus the current disposition option. This report documents results of the decision analysis.

  17. Melt-processed all-polymer distributed Bragg reflector laser.

    Science.gov (United States)

    Singer, Kenneth D; Kazmierczak, Tomasz; Lott, Joseph; Song, Hyunmin; Wu, Yeheng; Andrews, James; Baer, Eric; Hiltner, Anne; Weder, Christoph

    2008-07-07

    We have assembled and studied melt-processed all-polymer lasers comprising distributed Bragg reflectors that were fabricated in large sheets using a co-extrusion process and define the cavities for dye-doped compression-molded polymer gain core sheets. Distributed Bragg reflector (DBR) resonators consisting of 128 alternating poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) layers were produced by multilayer co-extrusion. Gain media were fabricated by compression-molding thermoplastic host poly notmers doped with organic laser dyes. Both processing methods can be used in high-throughput roll-to-roll manufacturing. Optically pumped DBR lasers assembled from these components display single and multimode lasing in the reflection band of the resonators, with a slope efficiency of nearly 19% and lasing thresholds as low as 90microJ/cm(2). The lasing wavelength can be controlled via the layer thickness of the DBR resonator films, and variation of the laser dye. Studies of threshold and efficiency are in agreement with models for end-pumped lasers.

  18. Remote Handling Devices for Disposition of Enriched Uranium Reactor Fuel Using Melt-Dilute Process

    International Nuclear Information System (INIS)

    Heckendorn, F.M.

    2001-01-01

    Remote handling equipment is required to achieve the processing of highly radioactive, post reactor, fuel for the melt-dilute process, which will convert high enrichment uranium fuel elements into lower enrichment forms for subsequent disposal. The melt-dilute process combines highly radioactive enriched uranium fuel elements with deleted uranium and aluminum for inductive melting and inductive stirring steps that produce a stable aluminum/uranium ingot of low enrichment

  19. Evaluation of feeds for melt and dilute process using an Analytical Hierarchy Process

    International Nuclear Information System (INIS)

    Krupa, J.F.

    2000-01-01

    WSRC was requested to evaluate whether nuclear materials other than aluminum-clad spent nuclear fuel should be considered for treatment to prepare them for disposal in the melt and dilute facility as part of the Treatment and Storage Facility (TSF) currently projected for construction in the L-Reactor process area. The Analytical Hierarchy Process using a ratings methodology was used to rank potential feed candidates for disposition through the Melt and Dilute facility proposed for disposition of Savannah River Site aluminum-clad spent nuclear fuel. Because of the scoping nature of this analysis, the expert team convened for this purpose concentrated on technical feasibility and potential cost impacts associated with using melt and dilute versus the current disposition option

  20. On melting dynamics and the glass transition. II. Glassy dynamics as a melting process.

    Science.gov (United States)

    Krzakala, Florent; Zdeborová, Lenka

    2011-01-21

    There are deep analogies between the melting dynamics in systems with a first-order phase transition and the dynamics from equilibrium in super-cooled liquids. For a class of Ising spin models undergoing a first-order transition--namely p-spin models on the so-called Nishimori line--it can be shown that the melting dynamics can be exactly mapped to the equilibrium dynamics. In this mapping the dynamical--or mode-coupling--glass transition corresponds to the spinodal point, while the Kauzmann transition corresponds to the first-order phase transition itself. Both in mean field and finite dimensional models this mapping provides an exact realization of the random first-order theory scenario for the glass transition. The corresponding glassy phenomenology can then be understood in the framework of a standard first-order phase transition.

  1. Gamma titanium aluminide production using the Induction Skull Melting (ISM) process

    International Nuclear Information System (INIS)

    Reed, S.

    1995-01-01

    Since 1985, more than 2,000 titanium aluminide heats have been produced using the Induction Skull Melting (ISM) process. The history of ISM/Gamma production will be discussed in this paper. Gamma titanium aluminide processing with Induction Skull Melting offers many advantages over other types of reactive alloy melting methods. These advantages will be discussed as well as drawbacks. Also, potential markets and applications for ISM/Gamma will be presented

  2. Applications of disorder-induced melting concept to critical-solute-accumulation processes

    International Nuclear Information System (INIS)

    Lam, N.Q.; Okamoto, P.R.; Heuer, J.K.

    2001-01-01

    A generalized version of the Lindemann melting criterion has recently been used to develop a unified thermodynamic description of disorder-induced amorphization and heat-induced melting. This concept of amorphization as a melting process is based on the fact that the melting temperature of a defective crystal driven far from equilibrium will decrease relative to that of its defect-free equilibrium state. The broader view of melting provides a new perspective of damage-accumulation processes such as radiation damage, ion implantation, ion beam mixing, plastic deformation, and fracture. For example, within this conceptual framework, disorder-induced amorphization is simply polymorphous melting of a critically disordered crystal at temperatures below the glass transition temperature. In the present communication, we discuss the application of the concept to two specific cases: amorphous phase formation during ion implantation and solute segregation-induced intergranular fracture

  3. Study of the melt pelletization process focusing on the micromeritic property of pellets.

    Science.gov (United States)

    Wong, T W; Chan, L W; Heng, P W

    2000-11-01

    Melt pelletization of lactose 450 M was carried out in an 8-l high shear mixer using PEG 3000 as the meltable binder. The pore size and size distribution of the melt pellets were determined using mercury intrusion porosimetry. The pore size distribution of melt pellets was found to be bimodal. With a higher binder concentration, post-melt impeller speed or longer post-melt processing time, the fraction of large pores in the agglomerates was reduced but the tendency of the agglomerates to develop sub-micron pores increased. The extent of formation of large pores was dependent on the interplay between the inter-particle distance of lactose particles and the contraction property of molten binder. High process temperature was associated with a greater amount of water loss from the melt agglomerates. The water vapor liberated from the lactose particles, was trapped in the molten PEG during the pelletization process. The formation of sub-micron pores was a result of escape of this water vapor on solidification of the molten PEG as well as agglomerate densification. The quantity of sub-micron pores produced was found to be related to the level of water loss. The melt agglomeration gave rise to large agglomerates when long post-melt processing time, high post-melt impeller speed or binder concentration was used.

  4. Experimental investigation of ice and snow melting process on pavement utilizing geothermal tail water

    International Nuclear Information System (INIS)

    Wang Huajun; Zhao Jun; Chen Zhihao

    2008-01-01

    Road ice and snow melting based on low temperature geothermal tail water is of significance to realize energy cascading utilization. A small scale ice and snow melting system is built in this work. Experiments of dynamic melting processes of crushed ice, solid ice, artificial snow and natural snow are conducted on concrete pavement. The results show that the melting process of ice and snow includes three phases: a starting period, a linear period and an accelerated period. The critical value of the snow free area ratio between the linear period and the accelerated period is about 0.6. The physical properties of ice and snow, linked with ambient conditions, have an obvious effect on the melting process. The difference of melting velocity and melting time between ice and snow is compared. To reduce energy consumption, the formation of ice on roads should be avoided if possible. The idling process is an effective pathway to improve the performance of melting systems. It is feasible to utilize geothermal tail water of about 40 deg. C for melting ice and snow on winter roads, and it is unnecessary to keep too high fluid temperatures during the practical design and applications. Besides, with the exception of solid ice, the density and porosity of snow and ice tend to be decreasing and increasing, respectively, as the ambient temperature decreases

  5. Processing and microstructure of melt spun NiAl alloys

    Science.gov (United States)

    Locci, I. E.; Noebe, R. D.; Moser, J. A.; Lee, D. S.; Nathal, M.

    1989-01-01

    The influence of various melt spinning parameters and the effect of consolidation on the microstructure of melt spun NiAl and NiAl + W alloys have been examined by optical and electron microscopy techniques. It was found that the addition of 0.5 at. pct W to NiAl results in a fine dispersion of W particles after melt spinning which effectively controls grain growth during annealing treatments or consolidation at temperatures between 1523 and 1723 K. Increased wheel speeds are effective at reducing both the ribbon thickness and grain size, such that proper choice of both composition and casting parameters can produce structures with grain sizes as small as 2 microns. Finally, fabrication of continuous fiber-reinforced composites which used pulverized ribbon as the matrix material was demonstrated.

  6. Heat and mass transfer in semiconductor melts during single-crystal growth processes

    Science.gov (United States)

    Kakimoto, Koichi

    1995-03-01

    The quality of large semiconductor crystals grown from melts is significantly affected by the heat and mass transfer in the melts. The current understanding of the phenomena, especially melt convection, is reviewed starting from the results of visualization using model fluids or silicon melt, and continuing to the detailed numerical calculations needed for quantitative modeling of processing with solidification. The characteristics of silicon flows are also reviewed by focusing on the Coriolis force in the rotating melt. Descriptions of flow instabilities are included that show the level of understanding of melt convection with a low Prandtl number. Based on hydrodynamics, the origin of the silicon flow structure is reviewed, and it is discussed whether silicon flow is completely turbulent or has an ordered structure. The phase transition from axisymmetric to nonaxisymmetric flow is discussed using different geometries. Additionally, surface-tension-driven flow is reviewed for Czochralski crystal growth systems.

  7. Mathematical modeling of quartz particle melting process in plasma-chemical reactor

    Energy Technology Data Exchange (ETDEWEB)

    Volokitin, Oleg, E-mail: volokitin-oleg@mail.ru; Volokitin, Gennady, E-mail: vgg-tomsk@mail.ru; Skripnikova, Nelli, E-mail: nks2003@mai.ru; Shekhovtsov, Valentin, E-mail: shehovcov2010@yandex.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Vlasov, Viktor, E-mail: rector@tsuab.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Ave., 634050, Tomsk (Russian Federation)

    2016-01-15

    Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ r{sub p} ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ r{sub p} ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature.

  8. Multiseeding with (100)/(100) Grain Junctions in Top Seeded Melt Growth Processed YBCO Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, C.J.; Gee, Y.A.; Hong, G.W. [Korea Atomic Energy Research Institute, Taejon (Korea); Kim, H.J.; Joo, J.H. [Sungkyunkwan University, Suwon (Korea); Han, S.C.; Han, Y.H.; Sung, T.H.; Kim, S.J. [Korea Electric Power Research Institute, Taejon (Korea)

    2000-06-01

    Multiseeding with (100)/(100) grain junctions of top-seeded melt growth (TSMG) processed YBCO superconductors was studied. Multiple seeding shortened the processing time for the fabrication of TSMG-processed YBCO superconductors. The relationship among the number of seeds, the levitation forces and the trapped magnetic fields of the TSMG-processed YBCO samples is reported. The characteristic of the (100)/(100) grain junction is discussed in terms of a wetting angle of a melt. (author). 25 refs., 7 figs.

  9. Research on Melt Degassing Processes of High Conductivity Hard Drawn Aluminum Wire

    Science.gov (United States)

    Xu, Xuexia; Feng, Yanting; Wang, Qing; Li, Wenbin; Fan, Hui; Wang, Yong; Li, Guowei; Zhang, Daoqian

    2018-03-01

    Degassing effects of ultrasonic and vacuum processes on high conductivity hard drawn aluminum melt were studied. Results showed that the degassing efficiency improved with the increase of ultrasonic power within certain range, stabilizing at 70% with 240W. For vacuum degassing process, hydrogen content of aluminum melt decreased with the loading time and was linear with logarithm of vacuum degree. Comparison of degassing effects of ultrasonic, vacuum, vacuum-ultrasonic degassing process showed that vacuum-ultrasonic process presented optimal effect.

  10. Melt-spun polylactic acid fibers: effect of cellulose nanowhiskers on processing and properties

    CSIR Research Space (South Africa)

    John, MJ

    2012-04-01

    Full Text Available Bio-based continuous fibers were processed from polylactic acid (PLA) and cellulose nanowhiskers (CNWs) by melt spinning. Melt compounding of master batches of PLA with 10 wt % CNWs and pure PLA was carried out using a twin-screw extruder in which...

  11. Melting processes of oligomeric α and β isotactic polypropylene crystals at ultrafast heating rates

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Xiaojing [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); He, Xuehao, E-mail: xhhe@tju.edu.cn, E-mail: scjiang@tju.edu.cn [Department of Chemistry, School of Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Jiang, Shichun, E-mail: xhhe@tju.edu.cn, E-mail: scjiang@tju.edu.cn [School of Material, Tianjin University, Tianjin 300072 (China)

    2014-02-07

    The melting behaviors of α (stable) and β (metastable) isotactic polypropylene (iPP) crystals at ultrafast heating rates are simulated with atomistic molecular dynamics method. Quantitative information about the melting processes of α- and β-iPP crystals at atomistic level is achieved. The result shows that the melting process starts from the interfaces of lamellar crystal through random dislocation of iPP chains along the perpendicular direction of lamellar crystal structure. In the melting process, the lamellar crystal gradually expands but the corresponding thickness decreases. The analysis shows that the system expansion lags behind the crystallinity decreasing and the lagging extents for α- and β-iPP are significantly different. The apparent melting points of α- and β-iPP crystals rise with the increase of the heating rate and lamellar crystal thickness. The apparent melting point of α-iPP crystal is always higher than that of β-iPP at differently heating rates. Applying the Gibbs-Thomson rule and the scaling property of the melting kinetics, the equilibrium melting points of perfect α- and β-iPP crystals are finally predicted and it shows a good agreement with experimental result.

  12. Cladding hull decontamination and densification process. Part 2. Densification by inductoslag melting

    International Nuclear Information System (INIS)

    Nelson, R.G.; Montgomery, D.R.

    1980-04-01

    The Inductoslag melting process was developed to densify Zircaloy-4 cladding hulls. It is a cold crucible process that uses induction heating, a segmented water-cooled copper crucible, and a calcium fluoride flux. Metal and flux are fed into the furnace through the crucible, located at the top of the furnace, and the finished ingot is withdrawn from the bottom of the furnace. Melting rates of 40 to 50 kg/h are achieved, using 100 to 110 kW at an average energy use of 2.5 kWh/kg. The quality of ingots produced from factory supplied cladding tubing is sufficient to satisfy nuclear grade standards. An ingot of Zircaloy-4, made from melted cladding tubing that had been autoclaved to near reactor exposure and then descaled by the hydrogen fluoride decontamination process prior to Inductoslag melting, did not meet nuclear grade standards because the hydrogen, nitrogen, and hardness levels were too high. Melting development work is described that could possibly be used to test the capability of the Inductoslag process to satisfactorily melt a variety and mix of materials from LWR reprocessing, decontamination, and storage options. Results of experiments are also presented that could be used to improve remote operation of the melting process

  13. Modeling of heat and mass transfer processes during core melt discharge from a reactor pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, T.N.; Bui, V.A.; Nourgaliev, R.R. [Royal Institute of Technology, Stockholm (Sweden)] [and others

    1995-09-01

    The objective of the paper is to study heat and mass transfer processes related to core melt discharge from a reactor vessel is a severe light water reactor accident. The phenomenology of the issue includes (1) melt convection in and heat transfer from the melt pool in contact with the vessel lower head wall; (2) fluid dynamics and heat transfer of the melt flow in the growing discharge hole; and (3) multi-dimensional heat conduction in the ablating lower head wall. A program of model development, validation and application is underway (i) to analyse the dominant physical mechanisms determining characteristics of the lower head ablation process; (ii) to develop and validate efficient analytic/computational methods for estimating heat and mass transfer under phase-change conditions in irregular moving-boundary domains; and (iii) to investigate numerically the melt discharge phenomena in a reactor-scale situation, and, in particular, the sensitivity of the melt discharge transient to structural differences and various in-vessel melt progression scenarios. The paper presents recent results of the analysis and model development work supporting the simulant melt-structure interaction experiments.

  14. Isotope enrichment of metal in the process of zone melting

    International Nuclear Information System (INIS)

    Troitskij, O.A.

    1976-01-01

    The possibility of using the zone melting technique with the purpose of isotope enrichment of metal has been checked. The experiments have been carried out with zinc and cadmium wires. After the experiment the long wire has been sectioned by 15 mm and in such a state has been subjected to mass spectrometric and neutron activation analysis. The dependence of isotope enrichment with zone passage is shown. The light isotopes 64 Zn in zinc and 106 Cd and 108 Cd in cadmium move following the zone enriching at the wire end

  15. Development of Physics-Based Numerical Models for Uncertainty Quantification of Selective Laser Melting Processes

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the proposed research is to characterize the influence of process parameter variability inherent to Selective Laser Melting (SLM) and performance effect...

  16. Downstream processing from melt granulation towards tablets: In-depth analysis of a continuous twin-screw melt granulation process using polymeric binders.

    Science.gov (United States)

    Grymonpré, W; Verstraete, G; Vanhoorne, V; Remon, J P; De Beer, T; Vervaet, C

    2018-03-01

    The concept of twin-screw melt granulation (TSMG) has steadily (re)-gained interest in pharmaceutical formulation development as an intermediate step during tablet manufacturing. However, to be considered as a viable processing option for solid oral dosage forms there is a need to understand all critical sources of variability which could affect this granulation technique. The purpose of this study was to provide an in-depth analysis of the continuous TSMG process in order to expose the critical process parameters (CPP) and elucidate the impact of process and formulation parameters on the critical quality attributes (CQA) of granules and tablets during continuous TSMG. A first part of the study dealt with the screening of various amorphous polymers as binder for producing high-dosed melt granules of two model drug (i.e. acetaminophen and hydrochlorothiazide). The second part of this study described a quality-by-design (QbD) approach for melt granulation of hydrochlorothiazide in order to thoroughly evaluate TSMG, milling and tableting stage of the continuous TSMG line. Using amorphous polymeric binders resulted in melt granules with high milling efficiency due to their brittle behaviour without producing excessive amounts of fines, providing high granule yields with low friability. Therefore, it makes them extremely suitable for further downstream processing. One of the most important CPP during TSMG with polymeric binders was the granulation-torque, which - in case of polymers with high T g - increased during longer granulation runs to critical levels endangering the continuous process flow. However, by optimizing both screw speed and throughput or changing to polymeric binders with lower T g it was possible to significantly reduce this risk. This research paper highlighted that TSMG must be considered as a viable option during formulation development of solid oral dosage forms based on the robustness of the CQA of both melt granules and tablets. Copyright © 2017

  17. Properties of melt processed chitosan and aliphatic polyester blends

    Energy Technology Data Exchange (ETDEWEB)

    Correlo, V.M. [3B' s Research Group-Biomaterials, Biodegradables and Biomimetics, Department of Polymer Engineering, University of Minho, Campus de Gualtar, Braga 4710-057 (Portugal); Boesel, L.F. [3B' s Research Group-Biomaterials, Biodegradables and Biomimetics, Department of Polymer Engineering, University of Minho, Campus de Gualtar, Braga 4710-057 (Portugal); Bhattacharya, M. [3B' s Research Group-Biomaterials, Biodegradables and Biomimetics, Department of Polymer Engineering, University of Minho, Campus de Gualtar, Braga 4710-057 (Portugal)]. E-mail: bhatt002@umn.edu; Mano, J.F. [3B' s Research Group-Biomaterials, Biodegradables and Biomimetics, Department of Polymer Engineering, University of Minho, Campus de Gualtar, Braga 4710-057 (Portugal); Neves, N.M. [3B' s Research Group-Biomaterials, Biodegradables and Biomimetics, Department of Polymer Engineering, University of Minho, Campus de Gualtar, Braga 4710-057 (Portugal); Reis, R.L. [3B' s Research Group-Biomaterials, Biodegradables and Biomimetics, Department of Polymer Engineering, University of Minho, Campus de Gualtar, Braga 4710-057 (Portugal)

    2005-08-25

    Chitosan was melt blended with poly-{epsilon}-caprolactone (PCL), poly(butylene succinate) (PBS), poly(lactic acid) (PLA), poly(butylene terephthalate adipate) (PBTA), and poly(butylene succinate adipate) (PBSA). For the chitosan/PBS blend, the amount of chitosan was varied from 25% to 70% by weight. The remaining polyesters had 50% of chitosan by weight. Addition of chitosan to PBS or PBSA tends to depress the melting temperature of the polyester. The crystallinity of the polyesters (PCL, PBS, PBSA) containing 50% chitosan decreased. Adding chitosan to the blends decreased the tensile strength but increased the tensile modulus. Chitosan displayed intermediate adhesion to the polyester matrix. Microscopic results indicate that the skin layer is polyester rich, while the core is a blend of chitosan and polyester. Fractured surface of chitosan blended with a high T {sub g} polymer, such as PLA, displayed a brittle fracture. Blends of chitosan with PCL, PBTA, or PBSA display fibrous appearances at the fractured surface due to the stretching of the polymer threads. Increasing the amount of chitosan in the blends also reduced the ductility of the fractured surface. The chitosan phase agglomerated into spherical domains or were clustered into sheaths. Pull-out of chitosan particles is evident in tensile-fractured surfaces for blends of chitosan with ductile polymers but absent in the blends with PLA. PBS displays a less lamellar orientation when compared to PCL or PBSA. The orientation of the polyesters (PCL, PBSA) does not seem to be affected by the addition of chitosan. The two main diffraction peaks observed using WAXS are unaffected by the addition of chitosan.

  18. Influence of different melt processings upon the microstructure and critical current of textured Y123

    Science.gov (United States)

    Monot, I.; Wang, J.; Delamare, M. P.; Provost, J.; Desgardin, G.

    1996-02-01

    Since directional solidification has been shown to be a successful way for achieving high critical current densities in bulk YBCO, many different ways have been developed for the sample preparation. In this study, the microstructure and superconducting properties of several processing routes (melt powder melt growth, powder melt processing, solid liquid melt growth) have been comparatively investigated. These processings are distinguished essentially from the combination of different starting precursors. It is shown that Y 2BaCuO 5 (Y211) excess in the nominal composition and/or 0.5 wt.% platinum doping strongly influence the shape of the Y211 formed during the high temperature melting stage of the texturing process. Spherical or thin needle-shaped Y211 grains can be obtained and their size controlled. Microstructural correaltions have shown that the nucleation and growth mechanisms of Y211 grains determine the further YBa 2Cu 3O 7-δ (Y123) formation. Thus, MPMG and SLMG processes appear to be governed by the diffusion of yttrium and also the dissolution mechanism of acicular Y211, while PMP process is mainly controlled by the diffusion of yttrium in the liquid phase to the Y123 growth front. However, the best Bean critical current densities between 0 and 1 T are obtained for the MPMG samples, but with improved processing conditions, the PMP process might be promising.

  19. Simulation of Hardening and Cooling Processes for Moving Melts in Special Casting Technologies

    Directory of Open Access Journals (Sweden)

    R. I. Esman

    2008-01-01

    Full Text Available A mathematical model and an algorithm for numerical solution of conjugate problem concerning hydrodynamics and heat transfer of hardening and cooling processes with liquid metal flow is given in the paper.Quantitative relationships between heating and hydrodynamic parameters of moving melts in the channels of metallic molds of special casting technologies have been determined in the paper. The analysis of temperature pattern and velocity field makes it possible to reveal an influence of boundary conditions on melt flow structure.

  20. A Novel Heat Treatment Process for Surface Hardening of Steel: Metal Melt Surface Hardening

    Science.gov (United States)

    Fu, Yong-sheng; Zhang, Wei; Xu, Xiaowei; Li, Jiehua; Li, Jun; Xia, Mingxu; Li, Jianguo

    2017-09-01

    A novel heat treatment process for surface hardening of steel has been demonstrated and named as "metal melt surface hardening (MMSH)." A surface layer with a thickness of about 400 μm and a hardness of about 700 HV has been achieved by ejecting AISI 304 stainless steel melt at a temperature of about 1783 K (1510 °C) onto the 40Cr steel surface. This proposed MMSH provides a very promising application for surface hardening of steel.

  1. Process to Continuously Melt, Refine and Cast High Quality Steel

    Energy Technology Data Exchange (ETDEWEB)

    None

    2005-09-01

    The purpose of this project is to conduct research and development targeted at designing a revolutionary steelmaking process. This process will deliver high quality steel from scrap to the casting mold in one continuous process and will be safer, more productive, and less capital intensive to build and operate than conventional steelmaking. The new process will produce higher quality steel faster than traditional batch processes while consuming less energy and other resources.

  2. STUDIES ON WETTABILITY OF STAINLESS STEEL 316L POWDER IN LASER MELTING PROCESS

    Directory of Open Access Journals (Sweden)

    KURIAN ANTONY

    2014-10-01

    Full Text Available Laser sintering is one of the techniques used in additive manufacturing processes. The main objective of the work is to study the effects of process parameters on wetting phenomenon and interfacial energy during laser melting of stainless steel powder. This paper reports wetting of laser melted powder particles and its use for the determination of surface energy of stainless steel powder under laser beam exposure. Process parameters such as laser power, scan speed and beam diameter are considered for study. This study also identifies the process parameters for better wettability which produces smooth surfaces.

  3. Vacuum Arc Melting Processes for Biomedical Ni-Ti Shape Memory Alloy

    Directory of Open Access Journals (Sweden)

    Tsai De-Chang

    2015-01-01

    Full Text Available This study primarily involved using a vacuum arc remelting (VAR process to prepare a nitinol shape-memory alloy with distinct ratios of alloy components (nitinol: 54.5 wt% to 57 wt%. An advantage of using the VAR process is the adoption of a water-cooled copper crucible, which effectively prevents crucible pollution and impurity infiltration. Optimising the melting production process enables control of the alloy component and facilitates a uniformly mixed compound during subsequent processing. This study involved purifying nickel and titanium and examining the characteristics of nitinol alloy after alloy melt, including its microstructure, mechanical properties, phase transition temperature, and chemical components.

  4. Melt state behaviour of PEEK and processing window interpretation for fast compression moulding process

    International Nuclear Information System (INIS)

    Bessard, Emeline; De Almeida, Olivier; Bernhart, Gerard

    2011-01-01

    Fast mould heating is nowadays possible by using induction technology for example with the Cage System registered developed by RocTool. It allows heating and cooling kinetics of about 100 deg. C per minute and new perspectives are thus possible to optimize the compression moulding process of long fibre reinforced thermoplastic composites. Indeed, a high forming temperature may favour polymer creep and so on composite consolidation. Nevertheless, the processing time of PEEK composite above melt temperature must be reduced to a few minutes due to the fast thermal degradation of the matrix. On the other hand, high cooling rates may have negative effect on matrix crystallinity. The proposed procedure consist in performing a few minutes isotherm around 300 deg. C during the fast cooling. It would favour a high degree of crystallinity of PEEK without extending the cycle time.

  5. Rheology as a tool for evaluation of melt processability of innovative dosage forms

    DEFF Research Database (Denmark)

    Aho, Johanna Maaria; Boetker, Johan P; Baldursdottir, Stefania

    2015-01-01

    Future manufacturing of pharmaceuticals will involve innovative use of polymeric excipients. Hot melt extrusion (HME) is an already established manufacturing technique and several products based on HME are on the market. Additionally, processing based on, e.g., HME or three dimensional (3D...... mixtures is highly dependent on the rheological properties of these systems, and rheological measurements should be considered as a more central part of the material characterization tool box when selecting suitable candidates for melt processing by, e.g., HME or 3D printing. The polymer processing......) printing, will have an increasingly important role when designing products for flexible dosing, since dosage forms based on compacting of a given powder mixture do not enable manufacturing of optimal pharmaceutical products for personalized treatments. The melt processability of polymers and API-polymer...

  6. A microscopic picture of the fast process in a polymer melt

    CERN Document Server

    Schmidt, W

    2002-01-01

    The picosecond process in a polymer melt is interpreted in terms of modes with a localized core, having an elastic dipole coupling to the viscoelastic medium. Fits of recent neutron scattering measurements of the fast process in (1,4)-polybutadiene at room temperature provide the dipole strength, together with a core diameter of about 0.6 nm. The result for the dipole strength is in good agreement with soft-potential fits of the low-temperature anomalies of polybutadiene. The finding suggests similar eigenvectors for the modes of the fast picosecond process in the melt and the tunneling modes in the glass phase. (orig.)

  7. Time and temperature dependence of the re-equilibration processes in plagioclase-hosted melt inclusions

    Science.gov (United States)

    Drignon, M. J.; Nielsen, R. L.; Tepley, F. J., III

    2015-12-01

    Interpretation of compositional data from melt inclusions and their host requires that we understand the effects of the two main post-entrapment processes. First, the crystals grow from the melt inclusion at the time the host lava erupts and cools. Second, the melt inclusion and its host undergo diffusive re-equilibration. These processes have been well established for olivine in olivine-hosted melt inclusions (Danyushevsky et al., 2000; 2004). No similar study has been done for plagioclase-hosted inclusions. To better understand post entrapment crystallization in these crystals, we have conducted a set of time-series experiments on plagioclases in Plagioclase Ultraphyric Basalts (PUBs, Nielsen et al., 1995; 1998; 2011; Sours-Page et al., 2000; Lange et al., 2012; 2013). Plagioclase crystals were heated near the entrapment temperature (1200-1230°C) for 30 min, 1h, 4 h and 4 days. Based on the S content of the melt inclusions, ~80% of the melt inclusions retain their integrity with respect to S after homogenization. It is based on the assumption that S will degas if the inclusion has ruptured, that all S is present as S=, and that the melts are initially sulfide saturated. This is not true for the major element composition of the melt inclusions. For run times of 30 min to 4 hours, the melt inclusions do not show significant compositional changes. However, after 4 days, the average composition of the re-homogenized melt inclusions is shifted toward higher MgO values and lower Al2O3 concentrations regardless of run temperature. These results suggest that re-homogenization techniques held at high temperature for less than 4 hours will return information that is most relevant to the re-homogenization of the post-entrapment crystals. The long term "drift" of the major elements suggests that diffusive re-equilibration with the host crystal takes place at a rate that is too slow to be seen during typical re-homogenization times used (e.g. 20 min-2 hrs.). Key words

  8. METAL-CERAMIC INTERFACES PRODUCED BY LASER MELT INJECTION PROCESSING

    NARCIS (Netherlands)

    DEHOSSON, JTM; VANDENBURG, M; Burg, M. van den

    1995-01-01

    This paper concentrates on the mechanical performance of various ceramic coatings of Cr2O3 on steel (SAF2205), as produced by CO2 laser processing. It is concluded that a firmly bonded coating of Cr2O3 on steel could be produced by high power laser processing. The actual interface strength of a

  9. Study of Using Solar Thermal Power for the Margarine Melting Heat Process.

    Science.gov (United States)

    Sharaf Eldean, Mohamed A; Soliman, A M

    2015-04-01

    The heating process of melting margarine requires a vast amount of thermal energy due to its high melting point and the size of the reservoir it is contained in. Existing methods to heat margarine have a high hourly cost of production and use fossil fuels which have been shown to have a negative impact on the environment. Thus, we perform an analytical feasibility study of using solar thermal power as an alternative energy source for the margarine melting process. In this study, the efficiency and cost effectiveness of a parabolic trough collector (PTC) solar field are compared with that of a steam boiler. Different working fluids (water vapor and Therminol-VP1 heat transfer oil (HTO)) through the solar field are also investigated. The results reveal the total hourly cost ($/h) by the conventional configuration is much greater than the solar applications regardless of the type of working fluid. Moreover, the conventional configuration causes a negative impact to the environment by increasing the amount of CO 2 , CO, and NO 2 by 117.4 kg/day, 184 kg/day, and 74.7 kg/day, respectively. Optimized period of melt and tank volume parameters at temperature differences not exceeding 25 °C are found to be 8-10 h and 100 m 3 , respectively. The solar PTC operated with water and steam as the working fluid is recommended as a vital alternative for the margarine melting heating process.

  10. Analysis of elementary process steps in industrial glass melting tanks: some ideas on innovations in industrial glass melting

    NARCIS (Netherlands)

    Beerkens, R.G.C.

    2008-01-01

    Conventional industrial glass furnaces show broad glass melt residence time distributions in the melting tanks and average residence times may be up to more than two days for high quality glass products, such as float glass or TV glass, despite the minimum residence times of 8-10 hours (or even less

  11. A process to produce effervescent tablets: fluidized bed dryer melt granulation.

    Science.gov (United States)

    Yanze, F M; Duru, C; Jacob, M

    2000-11-01

    The purpose of the present study was to apply melt granulation in a fluidized bed dryer (fluidized bed dryer melt granulation) to manufacture one-step effervescent granules composed of anhydrous citric acid and sodium bicarbonate to make tablets. This study permitted us to establish that such process parameters as concentrations of polyethylene glycol (PEG) 6000, residence times in the fluidized bed dryer, fineness of PEG6000, fineness of initial mixture effervescent systems, and efficiency of two lubricants markedly affect some granule and tablet characteristics. It is a dry process that is simple, rapid, effective, economical, reproducible, and particularly adapted to produce effervescent granules that are easily compressed into effervescent tablets.

  12. Possibilities of rationalization of the melting process proceeding in Ø 700 cupola

    OpenAIRE

    M.S. Soiński; A. Derda; A. Skoczylas; B. Zatoń; P. Mierzwa

    2010-01-01

    An attempt of rationalization of the cast iron melting process proceeding in a cupola has been taken on, based on the working parameters recorded during the first several hours of the cupola work. Examinations have been centred around the melting process taking place in a Ø 700 hot-blast cupola with a fixed receiver (forehearth). It has been found that a significant reduction in coke consumption is possible due to changes in cupola burdening without a detriment to furnace efficiency or the te...

  13. Possibilities of rationalization of the melting process proceeding in Ø 700 cupola

    Directory of Open Access Journals (Sweden)

    M.S. Soiński

    2010-01-01

    Full Text Available An attempt of rationalization of the cast iron melting process proceeding in a cupola has been taken on, based on the working parameters recorded during the first several hours of the cupola work. Examinations have been centred around the melting process taking place in a Ø 700 hot-blast cupola with a fixed receiver (forehearth. It has been found that a significant reduction in coke consumption is possible due to changes in cupola burdening without a detriment to furnace efficiency or the temperature of molten cast iron.

  14. Characterization of the melting process of PTFE using positron annihilation spectroscopy

    International Nuclear Information System (INIS)

    Honda, Y; Nishijima, S

    2015-01-01

    Poly(tetrafluoroethylene) (PTFE) is a semi-crystalline polymer and the lifetime of ortho-positronium(o-Ps) is known to be able to be separated into two components due to annihilation in the crystal region and in the amorphous region. The melting process of PTFE was investigated using positron annihilation spectroscopy and X-ray diffraction. The results indicated that volume expansion with an increase of temperature is dominantly due to the expansion of the amorphous region and a Ps bubble is formed at melting in both regions. The o-Ps relating to the crystal region definitely remains on the surface of crystal at the time of annihilation. The production of lower energy electrons at melting was deduced by the analysis of the Doppler broadened annihilation photopeak, and the increase in the number of such electrons was found to have great influence on the formation of the o-Ps and annihilation processes of positron and o-Ps. (paper)

  15. Microstructure and associated properties of YBa2Cu3Ox superconductors prepared by melt-processing techniques

    International Nuclear Information System (INIS)

    Balachandran, U.; Zhong, W.; Youngdahl, C.A.; Poeppel, R.B.

    1993-03-01

    From the standpoint of applications, melt-processed bulk YBa 2 Cu 3 O x (YBCO) superconductors are of considerable interest. We have studied the microstructure and levitation force of melt-processed YBCO, YBCO plus Y 2 BaCuO 5 , and YBCO plus Pt samples. Large single crystalline samples, grown using a seeding technique, were also studied. The levitation force is highest in melt-processed samples made by the seeding technique. 6 figs, 24 refs

  16. Melt pelletization in high shear mixer using a hydrophobic melt binder: influence of some apparatus and process variables.

    Science.gov (United States)

    Voinovich, D; Moneghini, M; Perissutti, B; Franceschinis, E

    2001-11-01

    The effects of process conditions and the apparatus variables on the granulometric characteristics of a formulation containing a hydrophobic binder (stearic acid), lactose and paracetamol prepared by melt pelletization process were investigated in a 10-litre high shear mixer. The factors under investigation were: impeller speed, massing time, type of impeller blades and presence of the deflector and their reciprocal interactions. Two granule characteristics were analysed: the percentage of aggregates larger than 3000 microm (Y(1)) and the yield of the 2000-microm pellet size fraction (Y(2)). In order to estimate simultaneously the above-mentioned factors, a particular experimental design was adopted, that allowed the reduction of the number of trials from 378 to 35 and took into consideration other uncontrolled factors with the aid of a block variable. Using the postulated model, we found the optimal operating conditions to minimize Y(1) and increase Y(2) by selecting the type of impeller, and by using an impeller speed lower than 300 rpm, a massing time of 8-9 min and by not using the deflector. Finally, the validity of the adopted strategy has been proved with an additional check point.

  17. Melt expulsion during ultrasonic vibration-assisted laser surface processing of austenitic stainless steel.

    Science.gov (United States)

    Alavi, S Habib; Harimkar, Sandip P

    2015-05-01

    Simultaneous application of ultrasonic vibrations during conventional materials processing (casting, welding) and material removal processes (machining) has recently been gaining widespread attention due to improvement in metallurgical quality and efficient material removal, respectively. In this paper, ultrasonic vibration-assisted laser surface melting of austenitic stainless steel (AISI 316) is reported. While the application of ultrasonic vibrations during laser processing delays the laser interaction with material due to enhancement of surface convection, it resulted in expulsion of melt from the irradiated region (forming craters) and transition from columnar to equiaxed dendritic grain structure in the resolidified melt films. Systematic investigations on the effect of ultrasonic vibrations (with vibrations frequency of 20 kHz and power output in the range of 20-40%) on the development of microstructure during laser surface melting (with laser power of 900 W and irradiation time in the range of 0.30-0.45 s) are reported. The results indicate that the proposed ultrasonic vibration-assisted laser processing can be designed for efficient material removal (laser machining) and improved equiaxed microstructure (laser surface modifications) during materials processing. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Effect of controlled crucible movement on melting process and carbon contamination in Czochralski silicon crystal growth

    Science.gov (United States)

    Liu, Xin; Han, Xue-Feng; Nakano, Satoshi; Kakimoto, Koichi

    2018-02-01

    In Czochralski silicon (CZ-Si) crystal growth, packed Si chunks experience collapse and volume shrinkage during the melting process. The axial movements of the crucible and the melting of the Si feedstock lead to dynamic thermal and flow fields and affect mass transport. To study the effect of crucible movement on the melting process and carbon (C) contamination, the cases of fixed and lifting crucible were investigated by the transient global simulation with dynamic mesh deformation. The gap width between the gas-guide and the top surface of Si feedstock was kept constant during the crucible lifting process. Impurity and species transport in Si feedstock and argon gas was investigated for the cases with the fixed and lifting crucibles. The comparison of C accumulation processes indicated that the lifting crucible case resulted in higher C contamination than that found in the fixed crucible case. Furthermore, lifting crucible cases with different gap widths were investigated to elaborate strategies for controlling the crucible movement for its effect on the melting process and C contamination in CZ-Si crystal growth. It was observed that the optimum gap width for C reduction results from the trade-off between the back diffusion and gas convection.

  19. Optimization of the caldasite processing conditions by alcaline melting

    International Nuclear Information System (INIS)

    Brown, A.E.P.

    1976-01-01

    A study has been done to recover economically the uranium and zirconium values of the ores at Pocos de Caldas Plateau in the state of Minas Gerais, Brazil. In a preliminar study, it was investigated the opening of the ore by alcaline fusion that were carried out in a temperature controlled furnace and the variables studied were the time, temperature and NaOH/ore ratio. The optimization procedure was based on the steepest Ascent Method developed by Box and Wilson, utilizing a complete 2 3 factorial design. The analysis of the data indicated the response optimum for the process in: time 1.52 +-0.1 hour; temperature 805 +-15degC; NaOH/ore ratio 1.7 ton/ton. Solubilizations higher than 97%ZrO 2 and recuperations nearly of 100%U 3 O 8 are obtained arouns this point [pt

  20. Solidification and Re-melting Phenomena During Slurry Preparation Using the RheoMetal™ Process

    Science.gov (United States)

    Payandeh, M.; Sabzevar, Mohsen Haddad; Jarfors, A. E. W.; Wessén, M.

    2017-12-01

    The melting sequence of the enthalpy exchange material (EEM) and formation of a slurry in the RheoMetal™ process was investigated. The EEM was extracted and quenched, together with a portion of the slurry at different processing times before complete melting. The EEM initially increased in size/diameter due to melt freezing onto its surface, forming a freeze- on layer. The initial growth of this layer was followed by a period of a constant diameter of the EEM with subsequent melting and decrease of diameter. Microstructural characterization of the size and morphology of different phases in the EEM and in the freeze-on layer was made. Dendritic equiaxed grains and eutectic regions containing Si particles and Cu-bearing particles and Fe-rich particles were observed in the as-cast EEM. The freeze-on layer consisted of dendritic aluminum tilted by about 30 deg in the upstream direction, caused by the rotation of the EEM. Energy dispersion spectroscopy analysis showed that the freeze-on layer had a composition corresponding to an alloy with higher melting point than the EEM and thus shielding the EEM from the surrounding melt. Microstructural changes in the EEM showed that temperature rapidly increased to 768 K (495 °C), indicated by incipient melting of the lowest temperature melting eutectic in triple junction grain boundary regions with Al2Cu and Al5Mg8Si6Cu2 phases present. As the EEM temperature increased further the binary Al-Si eutectic started to melt to form a region of a fully developed coherent mushy state. Experimental results and a thermal model indicated that as the dendrites spheroidized near to the interface at the EEM/freeze-on layer reached a mushy state with 25 pct solid fraction, coherency was lost and disintegration of the freeze-on layer took place. Subsequently, in the absence of the shielding effect from the freeze-on Layer, the EEM continued to disintegrate with a coherency limit of a solid fraction estimated to be 50 pct.

  1. Soy matrix drug delivery systems obtained by melt-processing techniques

    NARCIS (Netherlands)

    Vaz, C.M.; Doeveren, van P.F.N.M.; Reis, R.L.; Cunha, A.M.

    2003-01-01

    The aim of this study was to develop new soy protein drug delivery matrix systems by melt-processing techniques, namely, extrusion and injection moulding. The soy matrix systems with an encapsulated drug (theophylline, TH) were previously compounded by extrusion performed at two different pH values,

  2. Degradation of l-polylactide during melt processing with layered double hydroxides

    DEFF Research Database (Denmark)

    Gerds, Nathalie; Katiyar, Vimal; Koch, Christian Bender

    2012-01-01

    PLA was melt compounded in small-scale batches with two forms of laurate-modified magnesium–aluminum layered double hydroxide (Mg-Al-LDH-C12), the corresponding carbonate form (Mg-Al-LDH-CO3) and a series of other additives. Various methods were then adopted to characterize the resulting compounds...... in an effort to gain greater insights into PLA degradation during melt processing. PLA molecular weight reduction was found to vary according to the type of LDH additive. It is considered that the degree of particle dispersion and LDH exfoliation, and hence the accessibility of the hydroxide layer surfaces...

  3. A novel process for production of spherical PBT powders and their processing behavior during laser beam melting

    International Nuclear Information System (INIS)

    Schmidt, Jochen; Sachs, Marius; Fanselow, Stephanie; Wirth, Karl-Ernst; Peukert, Wolfgang; Zhao, Meng; Wudy, Katrin; Drexler, Maximilian; Drummer, Dietmar

    2016-01-01

    Additive manufacturing processes like laser beam melting of polymers are established for production of prototypes and individualized parts. The transfer to other areas of application and to serial production is currently hindered by the limited availability of polymer powders with good processability. Within this contribution a novel process route for the production of spherical polymer micron-sized particles of good flowability has been established and applied to produce polybutylene terephthalate (PBT) powders. Moreover, the applicability of the PBT powders in selective laser beam melting and the dependencies of process parameters on device properties will be outlined. First, polymer micro particles are produced by a novel wet grinding method. To improve the flowability the produced particles the particle shape is optimized by rounding in a heated downer reactor. A further improvement of flowability of the cohesive spherical PBT particles is realized by dry coating. An improvement of flowability by a factor of about 5 is achieved by subsequent rounding of the comminution product and dry-coating as proven by tensile strength measurements of the powders. The produced PBT powders were characterized with respect to their processability. Therefore thermal, rheological, optical and bulk properties were analyzed. Based on these investigations a range of processing parameters was derived. Parameter studies on thin layers, produced in a selective laser melting system, were conducted. Hence appropriate parameters for processing the PBT powders by laser beam melting, like building chamber temperature, scan speed and laser power have been identified.

  4. Effects of nanoparticles on melting process with phase-change using the lattice Boltzmann method

    Directory of Open Access Journals (Sweden)

    Ahmed M. Ibrahem

    Full Text Available In this work, the problem of nanoparticles dispersion effects on coupled heat transfer and solid-liquid phase change has been studied. The lattice Boltzmann method (LBM enthalpy-based is employed. The collision model of lattice Bhatnagar-Gross-Krook (LBGK is used to solve the problem of 1D melting by conduction. On the other hand, we use the model of multi-distribution functions (MDF to calculate the density, the velocity and the temperature for the problem of 2D melting by free convection, associated with different boundary conditions. In these simulations, the volume fractions of copper nanoparticles (0–2% added to water-base fluid and Rayleigh numbers of 103–105. We use the Chapman-Enskog expansion to derive the governing macroscopic quantities from the mesoscopic lattice Boltzmann equation. The results obtained by these models have been compared to an analytical solution or other numerical methods. The effects of nanoparticles on conduction and natural convection during the melting process have been investigated. Moreover, the influences of nanoparticles on moving of the phase change front, the thermal conductivity and the latent heat of fusion are also studied. Keywords: Lattice Boltzmann method, Nanofluids, Conduction melting, Convection melting, BGK collision model

  5. Percolation blockage: A process that enables melt pond formation on first year Arctic sea ice

    Science.gov (United States)

    Polashenski, Chris; Golden, Kenneth M.; Perovich, Donald K.; Skyllingstad, Eric; Arnsten, Alexandra; Stwertka, Carolyn; Wright, Nicholas

    2017-01-01

    Melt pond formation atop Arctic sea ice is a primary control of shortwave energy balance in the Arctic Ocean. During late spring and summer, the ponds determine sea ice albedo and how much solar radiation is transmitted into the upper ocean through the sea ice. The initial formation of ponds requires that melt water be retained above sea level on the ice surface. Both theory and observations, however, show that first year sea ice is so highly porous prior to the formation of melt ponds that multiday retention of water above hydraulic equilibrium should not be possible. Here we present results of percolation experiments that identify and directly demonstrate a mechanism allowing melt pond formation. The infiltration of fresh water into the pore structure of sea ice is responsible for blocking percolation pathways with ice, sealing the ice against water percolation, and allowing water to pool above sea level. We demonstrate that this mechanism is dependent on fresh water availability, known to be predominantly from snowmelt, and ice temperature at melt onset. We argue that the blockage process has the potential to exert significant control over interannual variability in ice albedo. Finally, we suggest that incorporating the mechanism into models would enhance their physical realism. Full treatment would be complex. We provide a simple temperature threshold-based scheme that may be used to incorporate percolation blockage behavior into existing model frameworks.

  6. Induction skull melting facility: an advanced system for electromagnetic processing of metals and alloys

    International Nuclear Information System (INIS)

    Sugilal, G.; Agarwal, K.

    2017-01-01

    Induction Skull Melting (ISM) is an advanced technology for processing highly refractory and extremely reactive metals and their alloys to produce ultra-high purity products. In ISM, the metallic charge is melted in a water-cooled, copper crucible. The crucible is segmented so that the magnetic field can penetrate into the metallic charge to be melted. By virtue of the strong electromagnetic stirring, the ISM technology can also be used to homogenize alloys of metals, which are difficult to be combined uniformly in composition due to large difference in specific gravity. In view of various important applications in frontier areas of material research, development and production, Bhabha Atomic Research Centre developed the ISM technology indigenously

  7. Cellular scanning strategy for selective laser melting: Generating reliable, optimized scanning paths and processing parameters

    DEFF Research Database (Denmark)

    Mohanty, Sankhya; Hattel, Jesper Henri

    2015-01-01

    method based uncertainty and reliability analysis. The reliability of the scanning paths are established using cumulative probability distribution functions for process output criteria such as sample density, thermal homogeneity, etc. A customized genetic algorithm is used along with the simulation model......Selective laser melting is yet to become a standardized industrial manufacturing technique. The process continues to suffer from defects such as distortions, residual stresses, localized deformations and warpage caused primarily due to the localized heating, rapid cooling and high temperature...... gradients that occur during the process. While process monitoring and control of selective laser melting is an active area of research, establishing the reliability and robustness of the process still remains a challenge.In this paper, a methodology for generating reliable, optimized scanning paths...

  8. High-density Bi-Pb-Sr-Ca-Cu-O superconductor prepared by rapid thermal melt processing

    Science.gov (United States)

    Moon, B. M.; Lalevic, B.; Kear, B. H.; McCandlish, L. E.; Safari, A.; Meskoob, M.

    1989-10-01

    A high quality, dense Bi-Pb-Sr-Ca-Cu-O superconductor has been successfully synthesized by rapid thermal melt processing. Conventionally sintered pellets were melted at 1200 °C, cooled rapidly, and then annealed. As-melted samples exhibited semiconductor behavior, which upon annealing became superconducting at 115 K [Tc(zero)=105 K]. A detailed study of various processing techniques has been carried out.

  9. Evaluating Acoustic Emission Signals as an in situ process monitoring technique for Selective Laser Melting (SLM)

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Karl A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Candy, Jim V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Guss, Gabe [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mathews, M. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-14

    In situ real-time monitoring of the Selective Laser Melting (SLM) process has significant implications for the AM community. The ability to adjust the SLM process parameters during a build (in real-time) can save time, money and eliminate expensive material waste. Having a feedback loop in the process would allow the system to potentially ‘fix’ problem regions before a next powder layer is added. In this study we have investigated acoustic emission (AE) phenomena generated during the SLM process, and evaluated the results in terms of a single process parameter, of an in situ process monitoring technique.

  10. Linear and nonlinear characterization of surfaces from a laser beam melt ablation process

    Energy Technology Data Exchange (ETDEWEB)

    Bube, Kevin [Institut fuer Chemie und Biologie des Meeres, Carl-von-Ossietzky Universitaet Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Neto, Camilo Rodrigues [Institut fuer Chemie und Biologie des Meeres, Carl-von-Ossietzky Universitaet Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); University of Sao Paulo, Av. Arlindo Bettio 1000, EACH, 03828-000 Sao Paulo (Brazil); Donner, Reik [Department of Physics, University of Potsdam, Am Neuen Palais 10, D-14469 Potsdam (Germany); Schwarz, Udo [Department of Physics, University of Potsdam, Am Neuen Palais 10, D-14469 Potsdam (Germany); Feudel, Ulrike [Institut fuer Chemie und Biologie des Meeres, Carl-von-Ossietzky Universitaet Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany)

    2006-04-07

    We apply linear and nonlinear methods to study the properties of surfaces generated by a laser beam melt ablation process. As a result we present a characterization and ordering of the surfaces depending on the adjusted process parameters. Our findings give some insight into the performance of two widely applied multifractal analysis methods-the detrended fluctuation analysis and the wavelet transform modulus maxima method-on short real world data.

  11. Rheology as a tool for evaluation of melt processability of innovative dosage forms.

    Science.gov (United States)

    Aho, Johanna; Boetker, Johan P; Baldursdottir, Stefania; Rantanen, Jukka

    2015-10-30

    Future manufacturing of pharmaceuticals will involve innovative use of polymeric excipients. Hot melt extrusion (HME) is an already established manufacturing technique and several products based on HME are on the market. Additionally, processing based on, e.g., HME or three dimensional (3D) printing, will have an increasingly important role when designing products for flexible dosing, since dosage forms based on compacting of a given powder mixture do not enable manufacturing of optimal pharmaceutical products for personalized treatments. The melt processability of polymers and API-polymer mixtures is highly dependent on the rheological properties of these systems, and rheological measurements should be considered as a more central part of the material characterization tool box when selecting suitable candidates for melt processing by, e.g., HME or 3D printing. The polymer processing industry offers established platforms, methods, and models for rheological characterization, and they can often be readily applied in the field of pharmaceutical manufacturing. Thoroughly measured and calculated rheological parameters together with thermal and mechanical material data are needed for the process simulations which are also becoming increasingly important. The authors aim to give an overview to the basics of rheology and summarize examples of the studies where rheology has been utilized in setting up or evaluating extrusion processes. Furthermore, examples of different experimental set-ups available for rheological measurements are presented, discussing each of their typical application area, advantages and limitations. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Friction Melt Bonding: An innovative process for aluminium-steel lap joints

    Directory of Open Access Journals (Sweden)

    Simar Aude

    2013-11-01

    Full Text Available A new process based on Friction Stir Welding has been developed to weld dissimilar metals, particularly steel and aluminum, in a lap-joint configuration. In this Friction Melt Bonding process, frictional heat generated by the rotating and translating tool brings about local and transient melting (Figure 1. Welding then occurs owing to controlled reactivity and solidification at the interface between the two plates. With an adequate choice of the welding parameters, low alloy steel and aluminium alloys have been successfully welded. Characterisation of the microstructure was systematically performed to highlight the influence of the process parameters, particularly the temperature cycle, on the steel-Al interface. The thickness of the intermetallic layer varies from a couple of micrometers to tens of micrometers depending on the advancing speed of the tool (Fig. 2. The lap shear properties of the joints were also investigated and analysed based on the morphology of the intermetallic layer.

  13. Challenges in Laser Sintering of Melt-Processable Thermoset Imide Resin

    Science.gov (United States)

    Chuang, Kathy C.; Gornet, Timothy; Koerner, Hilmar

    2016-01-01

    Polymer Laser Sintering (LS) is an additive manufacturing technique that builds 3D models layer by layer using a laser to selectively melt cross sections in powdered polymeric materials, following sequential slices of the CAD model. LS generally uses thermoplastic polymeric powders, such as polyamides (i.e. Nylon), and the resultant 3D objects are often weaker in their strength compared to traditionally processed materials, due to the lack of polymer inter-chain connection in the z-direction. The objective of this project is to investigate the possibility of printing a melt-processable RTM370 imide resin powder terminated with reactive phenylethynyl groups by LS, followed by a postcure in order to promote additional crosslinking to achieve higher temperature (250-300 C) capability. A preliminary study to build tensile specimens by LS and the corresponding DSC and rheology study of RTM370 during LS process is presented.

  14. Effect of the packing structure of silicon chunks on the melting process and carbon reduction in Czochralski silicon crystal growth

    Science.gov (United States)

    Liu, Xin; Nakano, Satoshi; Kakimoto, Koichi

    2017-06-01

    Carbon (C) contamination in Czochralski silicon (CZ-Si) crystal growth mainly originates from carbon monoxide (CO) generation on the graphite components, which reaches a maximum during the melting stage. Loading a crucible with poly-Si feedstock includes many technical details for optimization of the melting and growth processes. To investigate the effect of the packing structure of Si chunks on C accumulation in CZ-Si crystal growth, transient global simulations of heat and mass transport were performed for the melting process with different packing structures of poly-Si. The heat transport modeling took into account the effective thermal conductivity (ETC) of the Si feedstock, which is affected by the packing structure. The effect of the chunk size on the melting process and C accumulation were investigated by parametric studies of different packing structures. The heat transport and melting process in the crucible were affected by the ETC and the emissivity of the Si feedstock. It was found that smaller Si chunks packed in the upper part could speed up the melting process and smooth the power profile. Decreasing the duration of the melting process is favorable for reduction of C contamination in the Si feedstock. Parametric studies indicated that optimization of the melting process by the packing structure is possible and essential for C reduction in CZ-Si crystal growth.

  15. Investigation of melt agglomeration process with a hydrophobic binder in combination with sucrose stearate.

    Science.gov (United States)

    Heng, Paul Wan Sia; Wong, Tin Wui; Cheong, Wai See

    2003-08-01

    The melt agglomeration process of lactose powder with hydrogenated cottonseed oil (HCO) as the hydrophobic meltable binder was investigated by studying the physicochemical properties of molten HCO modified by sucrose stearates S170, S770 and S1570. The size, size distribution, micromeritic and adhesion properties of agglomerates as well as surface tension, contact angle, viscosity and specific volume of molten HCO, with and without sucrose stearates, were examined. The viscosity, specific volume and surface tension of molten HCO were found to be modified to varying extents by sucrose stearates which are available in different HLB values and melt properties. The growth of melt agglomerates was promoted predominantly by an increase in viscosity, an increase in specific volume or a decrease in surface tension of the molten binding liquid. The agglomerate growth propensity was higher with an increase in inter-particulate binding strength, agglomerate surface wetness and extent of agglomerate consolidation which enhanced the liquid migration from agglomerate core to periphery leading to an increased surface plasticity for coalescence. The inclusion of high concentrations of completely meltable sucrose stearate S170 greatly induced the growth of agglomerates through increased specific volume and viscosity of the molten binding liquid. On the other hand, the inclusion of incompletely meltable sucrose stearates S770 and S1570 promoted the agglomeration mainly via the reduction in surface tension of the molten binding liquid with declining agglomerate growth propensity at high sucrose stearate concentrations. In addition to being an agglomeration modifier, sucrose stearate demonstrated anti-adherent property in melt agglomeration process. The properties of molten HCO and melt agglomerates were dependent on the type and concentration of sucrose stearate added.

  16. Itraconazole formulation studies of the melt-extrusion process with mixture design.

    Science.gov (United States)

    Rambali, B; Verreck, G; Baert, L; Massart, D L

    2003-07-01

    Itraconazole is a poorly water soluble compound. One method to increase the aqueous solubility of itraconazole is through formation of a solid dispersion. The purpose of this study is to develop a 40% w/w itraconazole formulation through solid dispersion formation, using hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and hydroxypropylmethyl-cellulose (HPMC) as mixture components. The solid dispersion was obtained by melt-extrusion using a twin-screw corotating melt extruder. A D-optimal mixture design was applied for the development of the optimal itraconazole formulation. The itraconazole fraction varied between 20% w/w and 50% w/w in the mixture design and the HPMC and HP-beta-CD fractions varied between 10% w/w and 60% w/w. The itraconazole formulation was optimized by producing clear extrudates, minimizing the torque, and maximizing the glass transition temperature and the apparent itraconazole solubility in 0.1 N HCl. Regression models were developed for the torque, glass transition temperature, and apparent solubility of itraconazole. High itraconazole fraction in the mixture promoted a better melt processing (minimizes torque). High HPMC fraction (>33% w/w) resulted in clear extrudates, indicating a solid dispersion and resulted in high glass transition temperature of the melt. High HP-beta-CD fraction resulted in increased apparent itraconazole solubility in 0.1 N HCl. The optimal itraconazole formulation consisted of 45% w/w HPMC and 15% HP-beta-CD w/w.

  17. Degradation of PLA/ZnO and PHBV/ZnO composites prepared by melt processing

    Directory of Open Access Journals (Sweden)

    Alojz Anžlovar

    2018-03-01

    Full Text Available Composites of polylactide (PLA or poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV and ZnO nanoparticles (nZnO were prepared by melt processing. During extrusion and moulding nano ZnO formed aggregates with sizes between 0.5 and 5 μm in PLA and between 0.5 and 15 μm in PHBV. Nano ZnO acted as a disruptor of PLA crystallization process and shifted the polymer glass transition temperature to lower temperatures. This was explained by degradation of PLA polymer chains during melt processing. SEC, FTIR and 1H NMR confirmed that PLA degradation was correlated to nZnO concentration. The effect of nZnO on crystallization of PHBV matrix was much less intense which was shown by TGA. On the other hand, PHBV showed significantly lower thermal stability than PLA. ZnO participated as a reactant and an accelerator in the degradation reaction of PLA and at a smaller extent with PHBV. The results of this study revealed that addition of pure nZnO in concentrations higher than 0.1 wt.% is not recommended for the preparation of PLA/nZnO composites by melt processing while in the case of PHBV the nZnO concentration may be higher but it should not exceed 1.0 wt.%. The exposure time of these materials to high temperatures during melt processing should also be minimized.

  18. Submerged combustion melting processes for producing glass and similar materials, and systems for carrying out such processes

    Science.gov (United States)

    Charbonneau, Mark William

    2015-08-04

    Processes of controlling submerged combustion melters, and systems for carrying out the methods. One process includes feeding vitrifiable material into a melter vessel, the melter vessel including a fluid-cooled refractory panel in its floor, ceiling, and/or sidewall, and heating the vitrifiable material with a burner directing combustion products into the melting zone under a level of the molten material in the zone. Burners impart turbulence to the molten material in the melting zone. The fluid-cooled refractory panel is cooled, forming a modified panel having a frozen or highly viscous material layer on a surface of the panel facing the molten material, and a sensor senses temperature of the modified panel using a protected thermocouple positioned in the modified panel shielded from direct contact with turbulent molten material. Processes include controlling the melter using the temperature of the modified panel. Other processes and systems are presented.

  19. Microstructure within domains of melt-processed YBa2Cu3O7-x superconductors

    International Nuclear Information System (INIS)

    Alexander, K.B.; Goyal, A.; Kroeger, D.M.; Selvamanickam, V.; Salama, K.

    1992-01-01

    The microstructure within single domains of melt-processed YBa 2 Cu 3 O 7-x (1:2:3) material has been examined. Rather than composing a ''brick-wall'' structure, the stacked, parallel platelets within the domains are actually portions of a single crystal. A growth mechanism is proposed that is consistent with the observed microstructural features. The anisotropic nature of the growth of 1:2:3 results in gaps separating the platelets. The gaps, however, terminate within domains, resulting in interconnected single-crystalline material. The absence of weak-link behavior for current flow along the c axis and the high critical-current densities observed within domains of melt-processed 1:2:3 material are readily explained by the fact that current flow is solely through single-crystalline material

  20. Effect Of Turbulence Modelling In Numerical Analysis Of Melting Process In An Induction Furnace

    Directory of Open Access Journals (Sweden)

    Buliński P.

    2015-09-01

    Full Text Available In this paper, the velocity field and turbulence effects that occur inside a crucible of a typical induction furnace were investigated. In the first part of this work, a free surface shape of the liquid metal was measured in a ceramic crucible. Then a numerical model of aluminium melting process was developed. It took into account coupling of electromagnetic and thermofluid fields that was performed using commercial codes. In the next step, the sensitivity analysis of turbulence modelling in the liquid domain was performed. The obtained numerical results were compared with the measurement data. The performed analysis can be treated as a preliminary approach for more complex mathematical modelling for the melting process optimisation in crucible induction furnaces of different types.

  1. Processing of a metastable titanium alloy (Ti-5553 by selective laser melting

    Directory of Open Access Journals (Sweden)

    C. Zopp

    2017-09-01

    Material densities above 99.93% were achieved by optimisation of energy input during selective laser melting process. However, the use of reference fraction (10–63 μm allowed the highest material density. Regarding to surface quality, an impact of coarse grain (53–63 μm was identified and an optimised grain size distribution derived. An optimum averaged surface roughness could be calculated, using a grain size between 25–32 μm.

  2. The Remote Sensing and Measurement of Melting Processes on Greenland and Antarctica

    Science.gov (United States)

    Steiner, Nicholas

    We report measurements of melt-related processes for Antarctic and Greenland made using novel remote sensing algorithms and in-situ measurement techniques. First, persistent melting is mapped over Antarctica at high resolution using a novel melt-detection algorithm, based on wavelet-theory and multiscale analysis for the duration of the QuikSCAT satellite record (1999 through 2009). This novel approach is compared with threshold based methods, where melting is detected at 3dB below the winter mean backscatter, indicating an agreement to within 7 percent accuracy in yearly melt index [days-km2] and within 10 percent accuracy based automated weather station (AWS) comparisons due to the omission of short-duration melting events. In further comparison with Special Sensor Microwave/Image (SSMI) melting records, a higher degree of agreement (9 percent relative difference) is obtained by employing the wavelet-based approach than threshold-based (11 percent relative difference) methods. Secondly, we assess the validity of remote sensing based multispectral bathymetry from the analysis of concurrent in-situ multi-spectral and depth measurements collected over a supraglacial lake during early July 2010 in West Greenland (Lake Olivia, 69º36'35"N, 49º29'40"W). In particular, we evaluate lake bottom albedo and the water attenuation coefficient. Analysis of in-situ data (using a remotely controlled boat equipped with a GPS, sonar and a spectrometer) illustrates the exponential trend of the water-leaving reflectance with lake depth. The attenuation factors obtained are compared with those proposed in the literature. Finally, measured ablation rates at the bottom of the two lakes, collected during the summers of 2010 and 2011, are on the order of ˜ 6 cm/day, versus a rate of ˜ 2.5 - 3 cm/day in the case of bare ice of surrounding areas. These measurements are compared with a thermodynamic model forced with the outputs of a regional climate model. In general, the model is able

  3. Transient High-Temperature Processing of Silicates in Fulgurites as Analogues for Meteorite and Impact Melts

    Science.gov (United States)

    Parnell, J.; Thackrey, S.; Muirhead, D. K.; Wright, A. J.

    2008-03-01

    A fulgurite from the Sahara yielded petrographic data valuable as an analogue for highly reduced meteorite and impact melts, including iron silicide formation, devolatilization features, zircon melting and extreme melt heterogeneity.

  4. Modeling and Experimental Validation of the Electron Beam Selective Melting Process

    Directory of Open Access Journals (Sweden)

    Wentao Yan

    2017-10-01

    Full Text Available Electron beam selective melting (EBSM is a promising additive manufacturing (AM technology. The EBSM process consists of three major procedures: ① spreading a powder layer, ② preheating to slightly sinter the powder, and ③ selectively melting the powder bed. The highly transient multi-physics phenomena involved in these procedures pose a significant challenge for in situ experimental observation and measurement. To advance the understanding of the physical mechanisms in each procedure, we leverage high-fidelity modeling and post-process experiments. The models resemble the actual fabrication procedures, including ① a powder-spreading model using the discrete element method (DEM, ② a phase field (PF model of powder sintering (solid-state sintering, and ③ a powder-melting (liquid-state sintering model using the finite volume method (FVM. Comprehensive insights into all the major procedures are provided, which have rarely been reported. Preliminary simulation results (including powder particle packing within the powder bed, sintering neck formation between particles, and single-track defects agree qualitatively with experiments, demonstrating the ability to understand the mechanisms and to guide the design and optimization of the experimental setup and manufacturing process.

  5. Prolonged release matrix pellets prepared by melt pelletization. I. Process variables

    DEFF Research Database (Denmark)

    Thomsen, L.J.; Schaefer, T.; Sonnergaard, Jørn

    1993-01-01

    A melt pelletization process was investigated in an 8 litre laboratory scale high shear mixer using a formulation with paracetamol, glyceryl monostearate 40-50, and microcrystalline wax. The effects of jacket temperature, product temperature during massing, product load, massing time and impeller...... speed were investigated by means of factorially designed experiments. The maximum yield of pellets in the range of 500-1400 μm was found to approx. 90%. For process conditions preventing deposition of moist mass, the process was found to be reproducible. Impeller speed and massing time were found...

  6. Advanced Modeling of Cold Crucible Induction Melting for Process Control and Optimization

    Energy Technology Data Exchange (ETDEWEB)

    J. A. Roach; D. B. Lopukh; A. P. Martynov; B. S. Polevodov; S. I. Chepluk

    2008-02-01

    The Idaho National Laboratory (INL) and the St. Petersburg Electrotechnical University “LETI” (ETU) have collaborated on development and validation of an advanced numerical model of the cold crucible induction melting (CCIM) process. This work was conducted in support of the Department of Energy (DOE) Office of Environmental Management Technology and Engineering (EM-20) International Program. The model predicts quasi-steady state temperature distributions, convection cell configurations, and flow field velocities for a fully established melt of low conductivity non-magnetic materials at high frequency operations. The INL/ETU ANSYS© finite element model is unique in that it has been developed specifically for processing borosilicate glass (BSG) and other glass melts. Specifically, it accounts for the temperature dependency of key material properties, some of which change by orders of magnitude within the temperature ranges experienced (temperature differences of 500oC are common) in CCIM processing of glass, including density, viscosity, thermal conductivity, specific heat, and electrical resistivity. These values, and their responses to temperature changes, are keys to understanding the melt characteristics. Because the model has been validated, it provides the capability to conduct parametric studies to understand operational sensitivities and geometry effects. Additionally, the model can be used to indirectly determine difficult to measure material properties at higher temperatures such as resistivity, thermal conductivity and emissivity. The model can also be used to optimize system design and to predict operational behavior for specific materials and system configurations, allowing automated feedback control. This becomes particularly important when designing melter systems for full-scale industrial applications.

  7. Fabrication, properties and microstructure of the YBCO superconductor prepared by the powder melting process

    International Nuclear Information System (INIS)

    Lian, Zhou; Pingxiang, Zhang; Keguang, Wang; Jingrong, Wang; Zehua, Du; Ping, Ji

    1992-01-01

    Many studies of critical current density (Jc) from the point of view of application in liquid nitrogen have been made since the discovery of 90K YBa 2 Cu 3 O y (YBCO) superconductor. It is believed that the weak links between grains are responsible for the low Jc of sintered YBCO at magnetic fields. In this work, the authors propose a new approach -- the powder melting process (PMP) -- through which high Jc YBCO conductor have been fabricated using precursor powders of 211 and Ba-Cu-O phase, instead of 123 phase, as starting materials. The current density of PMP YBCO sample has been over 71000A/cm 2 at 1T, 77K without quench. The SEM and TEM study revealed the microstructural characteristics of PMP YBCO sample, well distributed fine 211 phase particles, microcracks-free, very clean grain boundaries and high density of crystal defects, which are believed to be responsible for its high Jc(B) values. Another direction to develop PMP is to reduce the melting temperature, which is essential for the fabrication of YBCO tape with metal substrate. A discussion is given of effects of processing parameters and microstructure on the technological advantages of this method. The YBCO conductors were fabricated via the continuously partial melting and unidirectional resolidification steps of the process using precursor powders of Y 2 BaCuO 5 and Ba-Cu-O phase as starting materials. Since the process enables the liquid phase to react fully with the fine 211 particles during the peritectic, no CuO and BaCuO 2 phase remained in 123 matrix. Strong flux pinning effect was introduced by the fine well-dispersive 211 particles via the very dense crystal defects induced around them. This new approach has potential for the fabrication of oxide conductor with metal substrates since its melting temperature is lower than that of other melting process by 50-70 degrees C. The authors have fabricated YBCO/Ag tape via PMP in N 2 atmosphere

  8. Processing thermally labile drugs by hot-melt extrusion: The lesson with gliclazide.

    Science.gov (United States)

    Huang, Siyuan; O'Donnell, Kevin P; Delpon de Vaux, Sophie M; O'Brien, John; Stutzman, John; Williams, Robert O

    2017-10-01

    The formation of molecularly dispersed amorphous solid dispersions by the hot-melt extrusion technique relies on the thermal and mechanical energy inputs, which can cause chemical degradation of drugs and polymeric carriers. Additionally, drug degradation may be exacerbated as drugs convert from a more stable crystalline form to a higher energy amorphous form. Therefore, it is imperative to study how drug degrades and evaluate methods to minimize drug degradation during the extrusion process. In this work, gliclazide was used as a model thermally labile drug for the degradation kinetics and process optimization studies. Preformulation studies were conducted using thermal analyses, and liquid chromatography-mass spectroscopy to identify drug degradation pathways and to determine initial extrusion conditions. Formulations containing 10% drug and 90% AFFINISOL™ HPMC HME 100LV were then extruded using a twin screw extruder, and the extrudates were characterized using X-ray powder diffraction, modulated dynamic scanning calorimetry, and potency testing to evaluate physicochemical properties. The energies of activation for both amorphous gliclazide, crystalline gliclazide, and gliclazide solution were calculated using the Arrhenius equation to further guide the extrusion optimization process. Preformulation studies identify two hydrolysis degradation pathways of gliclazide at elevated temperatures. The activation energy study indicates a significantly higher degradation rate for the amorphous gliclazide compared to the crystalline form. After optimization of the hot-melt extrusion process, including improved screw designs, machine setup, and processing conditions, gliclazide amorphous solid dispersion with ∼95% drug recovery was achieved. The ability to process thermally labile drugs and polymers using hot-melt extrusion will significantly expand the possible applications of this manufacturing process. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. An analogue model of melt segregation and accumulation processes in the Earth’s crust

    Directory of Open Access Journals (Sweden)

    Soesoo, Alvar

    2007-03-01

    Full Text Available An analogue experiment was carried out to model melt segregation from the solid rock matrix and its subsequent transport. Carbon dioxide gas and sand were used as analogue materials of crustal partial melt and host rock, respectively. The analogue model displays the diffusional transport mode at low flux rates and the transition to the ballistical mode as the response of the system to a higher gas flux. The ballistical mode is characterized by discontinuous transport and extraction of the gas phase in separate batches, which leads to the development of power law batch size distribution in the system. The gas is extracted preferentially in large batches and does not influence the state of the system and size distribution of remaining batches. The implications of the analogue model to real magmatic processes are supported by power law leucosome width distributions measured in several migmatite localities. The emergence of fractality and 1/f power spectrum of system fluctuations provide evidence of possible self-organized critical nature of melt segregation processes.

  10. Laser post-processing of Inconel 625 made by selective laser melting

    Science.gov (United States)

    Witkin, David; Helvajian, Henry; Steffeney, Lee; Hansen, William

    2016-04-01

    The effect of laser remelting of surfaces of as-built Selective Laser Melted (SLM) Inconel 625 was evaluated for its potential to improve the surface roughness of SLM parts. Many alloys made by SLM have properties similar to their wrought counterparts, but surface roughness of SLM-made parts is much higher than found in standard machine shop operations. This has implications for mechanical properties of SLM materials, such as a large debit in fatigue properties, and in applications of SLM, where surface roughness can alter fluid flow characteristics. Because complexity and netshape fabrication are fundamental advantages of Additive Manufacturing (AM), post-processing by mechanical means to reduce surface roughness detracts from the potential utility of AM. Use of a laser to improve surface roughness by targeted remelting or annealing offers the possibility of in-situ surface polishing of AM surfaces- the same laser used to melt the powder could be amplitude modulated to smooth the part during the build. The effects of remelting the surfaces of SLM Inconel 625 were demonstrated using a CW fiber laser (IPG: 1064 nm, 2-50 W) that is amplitude modulated with a pulse profile to induce remelting without spallation or ablation. The process achieved uniform depth of melting and improved surface roughness. The results show that with an appropriate pulse profile that meters the heat-load, surface features such as partially sintered powder particles and surface connected porosity can be mitigated via a secondary remelting/annealing event.

  11. Lead recovery from waste CRT funnel glass by high-temperature melting process.

    Science.gov (United States)

    Hu, Biao; Hui, Wenlong

    2018-02-05

    In this research, a novel and effective process for waste CRT funnel glass treatment was developed. The key to this process is removal of lead from the CRT funnel glass by high-temperature melting process. Sodium carbonate powder was used as a fusion agent, sodium sulfide serves as a catalytic agent and carbon powder acts as reducing agent. Experimental results showed that lead recovery rate increased with an increase in the amount of added sodium carbonate, sodium sulfide, carbonate, temperature and holding time initially, and then reached a stable value. The maximum lead recovery rate was approximately 94%, when the optimum adding amount of sodium carbonate, sodium sulfide, carbonate, temperature and holding time were 25%, 8%, 3.6%, 1200°C and 120min, respectively. In the high-temperature melting process, lead silicate in the funnel glass was firstly reduced, and then removed. The glass slag can be made into sodium and potassium silicate by hydrolysis process. This study proposed a practical and economical process for recovery of lead and utilization of waste glass slag. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Effects of Nanoparticles on Melting Process with Phase-Change Using the Lattice Boltzmann Method

    KAUST Repository

    Ibrahem, Ahmed M.

    2017-05-04

    In this work, the problem of nanoparticles dispersion effects on coupled heat transfer and solid-liquid phase change has been studied. The lattice Boltzmann method (LBM) enthalpy-based is employed. The collision model of lattice Bhatangar-Gross-Krook (LBGK) is used to solve the problem of 1D melting by conduction. On the other hand, we use the model of multi-distribution functions (MDF) to calculate the density, the velocity and the temperature for the problem of 2D melting by free convection, associated with different boundary conditions. In these simulations, the volume fractions of copper nanoparticles (0-2%) added to water-base fluid and Rayleigh numbers of 103to105. We use the Chapman-Enskog expansion to derive the governing macroscopic quantities from the mesoscopic lattice Boltzmann equation. The results obtained by these models have been compared to an analytical solution or other numerical methods. The effects of nanoparticles on conduction and natural convection during the melting process have been investigated. Moreover, the influences of nanoparticles on moving of the phase change front, the thermal conductivity and the latent heat of fusion are also studied.

  13. Aging Behaviour and Mechanical Performance of 18-Ni 300 Steel Processed by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Riccardo Casati

    2016-09-01

    Full Text Available An 18-Ni 300 grade maraging steel was processed by selective laser melting and an investigation was carried out on microstructural and mechanical behaviour as a function of aging condition. Owing to the rapid cooling rate, the as-built alloy featured a full potential for precipitate strengthening, without the need of a solution treatment prior to aging. The amount of reversed austenite found in the microstructure increased after aging and revealed to depend on aging temperature and time. Similarly to the corresponding wrought counterpart, also in the selective laser-melted 18-Ni 300 alloy, aging promoted a dramatic increase in strength with respect to the as-built condition and a drop in tensile ductility. No systematic changes were found in tensile properties as a function of measured amount of austenite. It is proposed that the submicrometric structure and the phase distribution inherited by the rapid solidification condition brought by selective laser melting are such that changes in tensile strength and ductility are mainly governed by the effects brought by the strengthening precipitates, whereas the concurrent reversion of the γ-Fe phase in different amounts seems to play a minor role.

  14. Melt-processable, radiation cross-linkable E--CTFE copolymer compositions

    International Nuclear Information System (INIS)

    Robertson, A.B.; Schaffhauser, R.J.

    1976-01-01

    Melt-processable, radiation cross-linkable ethylene/chlorotrifluoroethylene copolymer compositions are provided which contain about 0.1 to 5 percent by weight of the copolymer of a radiation cross-linking promoter, about 0.01 to 5 percent by weight of an anti-oxidant and about 0.1 to 30 precent by weight of an acid scavenger. Such compositions do not give off odors when irradiated to cross-link the copolymer and do not develop bubbles after irradiation. 15 claims, no drawings

  15. Modeling of the Melting Process in an AdBlue Tank

    OpenAIRE

    Klinga, Emil

    2015-01-01

    This master thesis is covering the modeling of the melting process in a tank filled with AdBlue. Due to AdBlue freezing at temperatures below -11 degree there is a need to add heat to be able to secure dosing in all situations. A rig for simulating freezing conditions is created with the possibility to store AdBlue in temperatures down to -40 degree. Temperatures are measured in and around the tank containing AdBlue and in the equipment used for adding heat. Two models are created from physic...

  16. Numerical simulation of complex part manufactured by selective laser melting process

    Science.gov (United States)

    Van Belle, Laurent

    2017-10-01

    Selective Laser Melting (SLM) process belonging to the family of the Additive Manufacturing (AM) technologies, enable to build parts layer by layer, from metallic powder and a CAD model. Physical phenomena that occur in the process have the same issues as conventional welding. Thermal gradients generate significant residual stresses and distortions in the parts. Moreover, the large and complex parts to manufacturing, accentuate the undesirable effects. Therefore, it is essential for manufacturers to offer a better understanding of the process and to ensure production reliability of parts with high added value. This paper focuses on the simulation of manufacturing turbine by SLM process in order to calculate residual stresses and distortions. Numerical results will be presented.

  17. Energy Saving Melting and Revert Reduction Technology: Innovative Semi-Solid Metal (SSM) Processing

    Energy Technology Data Exchange (ETDEWEB)

    Diran Apelian

    2012-08-15

    Semi-solid metal (SSM) processing has emerged as an attractive method for near-net-shape manufacturing due to the distinct advantages it holds over conventional near-net-shape forming technologies. These advantages include lower cycle time, increased die life, reduced porosity, reduced solidification shrinkage, improved mechanical properties, etc. SSM processing techniques can not only produce the complex dimensional details (e.g. thin-walled sections) associated with conventional high-pressure die castings, but also can produce high integrity castings currently attainable only with squeeze and low-pressure permanent mold casting processes. There are two primary semi-solid processing routes, (a) thixocasting and (b) rheocasting. In the thixocasting route, one starts from a non-dendritic solid precursor material that is specially prepared by a primary aluminum manufacturer, using continuous casting methods. Upon reheating this material into the mushy (a.k.a. "two-phase") zone, a thixotropic slurry is formed, which becomes the feed for the casting operation. In the rheocasting route (a.k.a. "slurry-on-demand" or "SoD"), one starts from the liquid state, and the thixotropic slurry is formed directly from the melt via careful thermal management of the system; the slurry is subsequently fed into the die cavity. Of these two routes, rheocasting is favored in that there is no premium added to the billet cost, and the scrap recycling issues are alleviated. The CRP (Trade Marked) is a process where the molten metal flows through a reactor prior to casting. The role of the reactor is to ensure that copious nucleation takes place and that the nuclei are well distributed throughout the system prior to entering the casting cavity. The CRP (Trade Marked) has been successfully applied in hyper-eutectic Al-Si alloys (i.e., 390 alloy) where two liquids of equal or different compositions and temperatures are mixed in the reactor and creating a SSM slurry. The process has been mostly

  18. Solidification process in melt spun Nd-Fe-B type magnets

    Energy Technology Data Exchange (ETDEWEB)

    Li, Changping [Iowa State Univ., Ames, IA (United States)

    1998-02-23

    A generalized solidification model has been developed based on a systematic investigation on the microstructure of melt spun Nd-Fe-B alloys. Melt spinning was conducted on initial stoichiometric and TiC added Nd2Fe14B (2-14-1) compositions to produce under, optimally and over quenched microstructures. Microstructural characterization was carried out by TEM, SEM, Optical microscopy, XRD, DTA, VSM and DC SQUID techniques. By taking the dendritic breakup during recalescence into consideration, this generalized model has successfully explained the solidification process of the melt spun Nd-Fe-B alloys. Challenging the conventional homogeneous nucleation models, the new model explains the fine and uniform equiaxed 2-14-1 microstructure in optimally quenched ribbons as a result of the breakup of the 2-14-1 dendrites which nucleate heterogeneously from the wheel surface and grow dendritically across the ribbon thickness due to the recalescence. Besides this dendritic breakup feature, the under quenched microstructure is further featured with another growth front starting with the primary solidification of Fe phase near the free side, which results in a coarsely grained microstructure with Fe dendritic inclusions and overall variation in microstructure across the ribbon thickness. In addition, because a epitaxy exists between the Fe phase and the 2-14-1, the so-formed coarse 2-14-1 grains may be textured. C-axis texturing was observed in under quenched ribbons. As a constraint to solidification models in this system, the cause and characteristics of this phenomenon has been studied in detail to test the authors proposed model, and agreement has been found. An extension has also been made to understand the solidification process when TiC is added, which suggests that Ti and C slow down the growth front of both Fe and 2-14-1 phase.

  19. A contribution to the electron-beam surface-melting process of metallic materials. Numerical simulation and experimental verification

    International Nuclear Information System (INIS)

    Bruckner, A.

    1996-08-01

    For the optimization of the surface melting process it is necessary to make many different experiments. Therefore, the simulation of the surface melting process becomes a major role for the optimization. Most of the simulations, developed for the laser surface melting process, are not usable for the electron-beam surface melting process, because of the different energy input and the possibility of high frequent movement of the electron-beam. In this thesis, a calculation model for electron-beam surface melting is presented. For this numerical simulation a variable volume source is used, which moves in axial direction with the same velocity as the vapor cavity into the material. With this calculation model also the high frequent movement of the electron-beam may be taken into account. The electron-beam diameter is measured with a method of drilling holes with short electron-beam pulses in thin foils. The diameter of the holes depends on the pulse length and reaches a maximal value, which is used for the diameter of the volume source in the calculation. The crack-formation, seen in many treated surfaces, is examined with the Acoustic-Emission Testing. The possibilities of the electron-beam surface melting process are shown with some experiments for different requirements of the treated surfaces, like increasing the hardness, reducing the porosity of a sintered material and the alloying of tin in an aluminium-silicon surface. (author)

  20. Strong isotope effects on melting dynamics and ice crystallisation processes in cryo vitrification solutions.

    Directory of Open Access Journals (Sweden)

    Oleg Kirichek

    Full Text Available The nucleation and growth of crystalline ice during cooling, and further crystallization processes during re-warming are considered to be key processes determining the success of low temperature storage of biological objects, as used in medical, agricultural and nature conservation applications. To avoid these problems a method, termed vitrification, is being developed to inhibit ice formation by use of high concentration of cryoprotectants and ultra-rapid cooling, but this is only successful across a limited number of biological objects and in small volume applications. This study explores physical processes of ice crystal formation in a model cryoprotective solution used previously in trials on vitrification of complex biological systems, to improve our understanding of the process and identify limiting biophysical factors. Here we present results of neutron scattering experiments which show that even if ice crystal formation has been suppressed during quench cooling, the water molecules, mobilised during warming, can crystallise as detectable ice. The crystallisation happens right after melting of the glass phase formed during quench cooling, whilst the sample is still transiting deep cryogenic temperatures. We also observe strong water isotope effects on ice crystallisation processes in the cryoprotectant mixture. In the neutron scattering experiment with a fully protiated water component, we observe ready crystallisation occurring just after the glass melting transition. On the contrary with a fully deuteriated water component, the process of crystallisation is either completely or substantially supressed. This behaviour might be explained by nuclear quantum effects in water. The strong isotope effect, observed here, may play an important role in development of new cryopreservation strategies.

  1. Reduction of carbon contamination during the melting process of Czochralski silicon crystal growth

    Science.gov (United States)

    Liu, Xin; Gao, Bing; Nakano, Satoshi; Kakimoto, Koichi

    2017-09-01

    Generation, incorporation, and accumulation of carbon (C) were investigated by transient global simulations of heat and mass transport during the melting process of Czochralski silicon (CZ-Si) crystal growth. Contact reaction between the quartz crucible and graphite susceptor was introduced as an extra origin of C contamination. The contribution of the contact reaction on C accumulation is affected by the back diffusion of C monoxide (CO) from the gap between the gas-guide and the crucible. The effect of the gas-guide coating on C reduction was elucidated by taking the reaction between the silicon carbide (SiC) coating and gaseous Si monoxide (SiO) into account. Application of the SiC coating on the gas-guide could effectively reduce the C contamination because of its higher thermochemical stability relative to that of graphite. Gas flow control on the back diffusion of the generated CO was examined by the parametric study of argon gas flow rate. Generation and back diffusion of CO were both effectively suppressed by the increase in the gas flow rate because of the high Péclet number of species transport. Strategies for C content reduction were discussed by analyzing the mechanisms of C accumulation process. According to the elucidated mechanisms of C accumulation, the final C content depends on the growth duration and contamination flux at the gas/melt interface.

  2. Numerical Simulations of Melting-Crystallisation Processes at the Boundaries Between Magma Oceans and Solid Mantle

    Science.gov (United States)

    Bolrão, D. P.; Rozel, A.; Morison, A.; Labrosse, S.; Tackley, P. J.

    2017-12-01

    The idea that the Earth had a global magma ocean, mostly created by impacts, core formation, radiogenic and tidal heating, is well accepted nowadays. When this ocean starts to crystallise, if the melt is denser than the solid, a basal magma ocean is created below the solid part. These two magma oceans influence the dynamics and evolution of solid mantle. Near the boundaries, the vertical flow in the solid part creates a topography. If this topography is destroyed by melting/crystallisation processes in a time scale much shorter than the time needed to adjust the topography by viscous relaxation, then matter can cross the boundary. In this case, the boundary is said to be permeable. On the other hand, if this time is longer, matter cannot cross and the boundary is said impermeable. This permeability is defined by a non-dimensional phase change number, φ, introduced by Deguen, 2013. This φ is the ratio of the two timescales mentioned, and defines a permeable boundary when φ « 1, and an impermeable one when φ » 1. To understand the impact of magma oceans on the dynamics of the solid mantle, we use the convection code StagYY, with a 2D spherical annulus geometry, to compute the convection of the solid part. Our results show different convection behaviours depending on the type of boundary chosen. For the permeable case, we investigate the thermo-compositional evolution of the solid domain, explicitly taking into account the compositional evolution of the magma oceans. Reference: Deguen, R. Thermal convection in a spherical shell with melting/freezing at either or both of its boundaries. Journal of Earth Science, Vol. 24, No. 5, p. 669-682, 2013. doi: 10.1007/s12583-013-0364-8

  3. Microstructures, hardness and bioactivity of hydroxyapatite coatings deposited by direct laser melting process

    Energy Technology Data Exchange (ETDEWEB)

    Tlotleng, Monnamme, E-mail: MTlotleng@csir.co.za [Laser Materials Processing Group, National Laser Center CSIR, Pretoria 0001 (South Africa); Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park, Kingsway Campus, Johannesburg 2006 (South Africa); Akinlabi, Esther [Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park, Kingsway Campus, Johannesburg 2006 (South Africa); Shukla, Mukul [Department of Mechanical Engineering Technology, University of Johannesburg, Doornfontein Campus, Johannesburg 2006 (South Africa); Department of Mechanical Engineering, MNNIT, Allahabad, UP 211004 (India); Pityana, Sisa [Laser Materials Processing Group, National Laser Center CSIR, Pretoria 0001 (South Africa); Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria 0001 (South Africa)

    2014-10-01

    Hydroxyapatite (HAP) coatings on bioinert metals such as Ti–6Al–4V are necessary for biomedical applications. Together, HAP and Ti–6Al–4V are biocompatible and bioactive. The challenges of depositing HAP on Ti–6Al–4V with traditional thermal spraying techniques are well founded. In this paper, HAP was coated on Ti–6Al–4V using direct laser melting (DLM) process. This process, unlike the traditional coating processes, is able to achieve coatings with good metallurgical bonding and little dilution. The microstructural and mechanical properties, chemical composition and bio-activities of the produced coatings were studied with optical microscopy, scanning electron microscope equipped with energy dispersive X-ray spectroscopy, and Vickers hardness machine, and by immersion test in Hanks' solution. The results showed that the choice of the laser power has much influence on the evolving microstructure, the mechanical properties and the retainment of HAP on the surface of the coating. Also, the choice of laser power of 750 W led to no dilution. The microhardness results inferred a strong intermetallic–ceramic interfacial bonding; which meant that the 750 W coating could survive long in service. Also, the coating was softer at the surface and stronger in the heat affected zones. Hence, this process parameter setting can be considered as an optimal setting. The soak tests revealed that the surface of the coating had unmelted crystals of HAP. The CaP ratio conducted on the soaked coating was 2.00 which corresponded to tetra calcium phosphate. This coating seems attractive for metallic implant applications. - Highlights: • Characteristics of HAP coatings produced on Ti-6Al-4V achieved with direct laser melting are reported. • Optimal process parameters necessary to achieve biocompatible coating are reported. • The SEM micrograph of the soaked HAP coating revealed partially melted crystals of HAP. • The HAP coating was retained at the surface of

  4. Physico-chemical Processes on the Heterogeneous Boundary of Oxides Melts and Molten Iron with the Sacrificed Materials

    International Nuclear Information System (INIS)

    Udalov, Yu.P.; Lavrov, B.A.

    2004-01-01

    Interaction of oxides melts and iron with iron oxide (the main component of sacrificial materials) is studied. The interaction on the boundary of Fe 2 O 3 and melts of PbO, Pb 2 SiO 4 , PbSiO 3 , Na 2 SiO 3 , Na 4 SiO 4 , Na 2 Si2O 5 , iron melt is considered. Comparison is given of the results obtained with data acquired in investigating the interaction on the boundary of Fe 2 O 3 and corium. Ablation for all the types of melts is found to get started with diffusion dissolution of Fe 2 O 3 in the melt followed by redox reaction accompanied by evolution of molecular oxygen. The molecular oxygen disconnects SM grains in the zone of the reaction and due to it the ablation is displaced from diffusion range to kinetic range and becomes pulsating. The rate of the redox reaction is dependent on the oxygen ion concentration (the higher concentration of oxygen ions in melt the higher speed of molecular oxygen evolution is). It is shown that molten Fe does not wet Fe 2 O 3 at 1600-1800 deg C that makes the ablation process slow. To accelerate the Fe 2 O 3 interaction with the iron melt it is necessary to add oxides of 3d- elements (CuO, MnO, NiO, CoO ) into Fe 2 O 3 . (authors)

  5. Depolymerization of post-consumer PET with multifunctional alcohol through melt processing

    International Nuclear Information System (INIS)

    Lessa, Tathiane C.R.F.; Mendes, Luis C.; Dias, Marcos L.

    2009-01-01

    The purpose of this study was to prepare oligomers from post-consumer PET with multifunctional alcohol, through melt processing, aiming to develop a new material, able to play a role as filler or property modifier. Maintaining constants the process conditions, content and kind of catalyst, the influence of the solvolysis agent on the PET depolymerization was investigated. The products were evaluated by wide-angle X-ray diffraction (WAXD) and thermogravimetry (TG/DTG). The changes in the WAXD curves and the shift of the maximum degradation temperature suggested that the ester linkages were broken being the ethylene glycol moieties replaced with hydroxyl-terminal groups of the multifunctional alcohol, as result of a transesterification reaction. The chemical structure of the new ester was named 'star-branching polymer'. (author)

  6. Structural evolution process of isotactic polypropylene in the isothermal crystallization from the melt

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Kummetha Raghunatha; Tashiro, Kohji; Hanesaka, Makoto [Department of Future Industry-Oriented Basic Science and Materials, Graduate School of Engineering, Toyota Technological Institute, Tempaku, Nagoya 468-8511 (Japan); Sakurai, Takashi; Yamaguchi, Noburu [Petrochemical Research Laboratory, Sumitomo Chemical Co. Ltd., Chiba 299-0295 (Japan); Sasaki, Sono; Masunaga, Hiroyasu; Takata, Masaki, E-mail: ktashiro@toyota-ti.ac.j [Japan Synchrotron Radiation Research Institute (JASRI), Kouto, Sayo-gun, Hyogo, 679-5198 (Japan)

    2009-08-01

    The melt-isothermal crystallization behaviour has been investigated for isotactic polypropylene (iPP) by means of time-resolved simultaneous measurements of small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) using synchrotron radiation source in SPring-8. The time-resolved Fourier-transform infrared spectral (FTIR) measurements were also performed to clarify the formation process of helices. The SAXS data were analyzed on the basis of Guinier (isolated domains) and Debye-Bueche (correlated domains) theories and correlation function (stacked lamellae). The results were combined with the FTIR data, allowing us to draw the concrete structural evolution process including the formation of regular helices and their growth, the correlation of higher density domains consisting of these helices, and the increment of correlation between the neighbouring lamellae to build up the stacked lamellar structure of higher crystallinity.

  7. Tailoring Selective Laser Melting Process Parameters for NiTi Implants

    Science.gov (United States)

    Bormann, Therese; Schumacher, Ralf; Müller, Bert; Mertmann, Matthias; de Wild, Michael

    2012-12-01

    Complex-shaped NiTi constructions become more and more essential for biomedical applications especially for dental or cranio-maxillofacial implants. The additive manufacturing method of selective laser melting allows realizing complex-shaped elements with predefined porosity and three-dimensional micro-architecture directly out of the design data. We demonstrate that the intentional modification of the applied energy during the SLM-process allows tailoring the transformation temperatures of NiTi entities within the entire construction. Differential scanning calorimetry, x-ray diffraction, and metallographic analysis were employed for the thermal and structural characterizations. In particular, the phase transformation temperatures, the related crystallographic phases, and the formed microstructures of SLM constructions were determined for a series of SLM-processing parameters. The SLM-NiTi exhibits pseudoelastic behavior. In this manner, the properties of NiTi implants can be tailored to build smart implants with pre-defined micro-architecture and advanced performance.

  8. Semi-solid process of 2024 wrought aluminum alloy by strain induced melt activation

    Directory of Open Access Journals (Sweden)

    Surachai Numsarapatnuk

    2013-10-01

    Full Text Available The aim of this study is to develop a production process of a fine globular structure feedstock of the 2024 aluminumalloy suitable for subsequent semi-solid forming. The 2024 wrought aluminum alloy was first annealed to reduce the effect ofwork hardening. Then, strain was induced in the alloy by cold compression. After that the microstructural evolution duringpartial melting was investigated. The samples were subjected to full annealing at 415°C for 3 hrs prior to cold compression of40% reduction of area (RA with 3 mm/min strain rate. After that samples were partially melted at 620°C with varying holdingtime from 0 to 60 min followed by water quenching. The grain size and the average grain diameter of solid grains weremeasured using the linear intercept method. The globularization was interpreted in terms of shape factor. Liquid fraction andthe distribution of the eutectic liquid was also investigated. It was found that during partial melting, the globular morphologywas formed by the liquid wetting and fragmentation of high angle boundaries of recrystallized grains. The suitable semi-solidmicrostructure was obtained from a condition of full annealing, 40% cold working and partial melting at 620°C for 6 minholding time. The near globular grains obtained in the range of 0-60 min consisted of uniform spheroid grains with an averagegrain diameter ranged from 73 to 121 m, quenched liquid fraction was approximately 13–27% and the shape factor was greaterthan 0.6. At a holding time of less than 6 min, grain coarsening was dominant by the immigration of high-angle grainboundaries. At a longer holding time, liquid fraction increased and Ostwald ripening was dominant. The coarsening rateconstant for the 2024 Al alloy was 400.36 mm3.s-1. At a soaking time of 60 min, it was found that a minimum diameter differencewas 1.06% with coarsening index n=3 in a power law equation. The non-dendritic slug of 2024 alloy was rapid compressedinto a disc with 90%RA

  9. Synthesis and Characterization of Solution and Melt Processible Poly(Acrylonitrile-Co-Methyl Acrylate) Statistical Copolymers

    Science.gov (United States)

    Pisipati, Padmapriya

    Polyacrylonitrile (PAN) and its copolymers are used in a wide variety of applications ranging from textiles to purification membranes, packaging material and carbon fiber precursors. High performance polyacrylonitrile copolymer fiber is the most dominant precursor for carbon fibers. Synthesis of very high molecular weight poly(acrylonitrile-co-methyl acrylate) copolymers with weight average molecular weights of at least 1.7 million g/mole were synthesized on a laboratory scale using low temperature, emulsion copolymerization in a closed pressure reactor. Single filaments were spun via hybrid dry-jet gel solution spinning. These very high molecular weight copolymers produced precursor fibers with tensile strengths averaging 954 MPa with an elastic modulus of 15.9 GPa (N = 296). The small filament diameters were approximately 5 im. Results indicated that the low filament diameter that was achieved with a high draw ratio, combined with the hybrid dry-jet gel spinning process lead to an exponential enhancement of the tensile properties of these fibers. Carbon fibers for polymer matrix composites are currently derived from polyacrylonitrile copolymer fiber precursors where solution spinning accounts for ˜40 % of the total fiber production cost. To expand carbon fiber applications into the automotive industry, the cost of the carbon fiber needs to be reduced from 8 to ˜3-5. In order to develop an alternative melt processing route several benign plasticizers have been investigated. A low temperature, persulfate-metabisulfite initiated emulsion copolymerization was developed to synthesize poly(acrylonitrile-co-methyl acrylate) copolymers with acrylonitrile contents between 91-96 wt% with a molecular weight range of 100-200 kg/mol. This method was designed for a potential industrial scale up. Furthermore, water was investigated as a potential melting point depressant for these copolymers. Twenty-five wt% water lead to a decrease in the Tm of a 93/7 wt/wt % poly

  10. Development and evaluation of prolonged release pellets obtained by the melt pelletization process.

    Science.gov (United States)

    Hamdani, Jamila; Moës, André J; Amighi, Karim

    2002-10-01

    This study was performed in order to evaluate the possibility of obtaining prolonged release matrix pellets by a melt pelletization process in a laboratory high shear mixer (Mi-Pro, Pro-C-epT). Phenylephrine hydrochloride pellet formulations based on lactose 450 mesh and a mixture of Compritol 888 and Precirol ATO 5 as melting binders were evaluated. The fatty binder content of pellets was substantially increased (from 18 to 80% w/w). The effects of jacket temperature, massing time (MT) and impeller speed (IS) on the pellet characteristics were investigated. It was shown that pellets of narrow size distribution can be produced by using an IS of 800 rpm, a chopper speed of 4000 rpm and a MT of 8 min. On the other hand, the applicability of this technique for the production of sustained-release pellets using ciprofloxacin hydrochloride, ketoprofen and theophylline as less water soluble model drugs than phenylephrine hydrochloride was also studied. This study demonstrated that formulations based on an appropriate mixture of Precirol and Compritol can be used to produce in a short time prolonged release pellets for very hydrosoluble drugs like phenylephrine hydrochloride as well as for the other drugs tested.

  11. Effect of Orifice Diameter on Bubble Generation Process in Melt Gas Injection to Prepare Aluminum Foams

    Science.gov (United States)

    Yuan, Jianyu; Li, Yanxiang; Wang, Ningzhen; Cheng, Ying; Chen, Xiang

    2016-06-01

    The bubble generation process in conditioned A356 alloy melt through submerged spiry orifices with a wide diameter range (from 0.07 to 1.0 mm) is investigated in order to prepare aluminum foams with fine pores. The gas flow rate and chamber pressure relationship for each orifice is first determined when blowing gas in atmospheric environment. The effects of chamber pressure ( P c) and orifice diameter ( D o) on bubble size are then analyzed separately when blowing gas in melt. A three-dimensional fitting curve is obtained illustrating both the influences of orifice diameter and chamber pressure on bubble size based on the experimental data. It is found that the bubble size has a V-shaped relationship with orifice diameter and chamber pressure neighboring the optimized parameter ( D o = 0.25 mm, P c = 0.4 MPa). The bubble generation mechanism is proposed based on the Rayleigh-Plesset equation. It is found that the bubbles will not be generated until a threshold pressure difference is reached. The threshold pressure difference is dependent on the orifice diameter, which determines the time span of pre-formation stage and bubble growth stage.

  12. Monitoring of a Hot Melt Coating Process via a Novel Multipoint Near-Infrared Spectrometer.

    Science.gov (United States)

    Hohl, Roland; Scheibelhofer, Otto; Stocker, Elena; Behzadi, Sharareh Salar; Haack, Detlev; Koch, Kai; Kerschhaggl, Peter; Lochmann, Dirk; Sacher, Stephan; Zimmer, Andreas

    2017-01-01

    The aim of the present work was to develop a PAT strategy for the supervision of hot melt coating processes. Optical fibers were placed at various positions in the process chamber of a fluid bed device. Experiments were performed to determine the most suitable position for in-line process monitoring, taking into account such requirements as a good signal to noise ratio, the mitigation of dead zones, the ability to monitor the product over the entire process, and reproducibility. The experimental evidence suggested that the position at medium fluid bed height, looking towards the center, i.e., normal to particle movement, proved to be the most reliable position. In this study, the advantages of multipoint monitoring are shown, and an in-line-implementation was created. This enabled the real-time supervision of the process, including the fast detection of inhomogeneities and disturbances in the process chamber, and the compensation of sensor malfunction. In addition, a model for estimating the particle size distribution via NIR was successfully created. This ensures that the quality of the product and the endpoint of the coating process can be determined correctly.

  13. Heat and mass transfer during the inductive skull melting process of glasses and oxides; Waerme- und Stofftransport beim induktiven Skull-Schmelzen von Glaesern und Oxiden

    Energy Technology Data Exchange (ETDEWEB)

    Nacke, Bernard; Niemann, Benjamin [Leibniz Univ. Hannover (Germany). Inst. fuer Elektroprozesstechnik; Schlesselmann, Dirk [Auer Lighting GmbH, Bad Gandersheim (Germany)

    2013-03-15

    The skull melting technology is a melting process for innovative materials in the range of glasses. A hitherto unknown problem under glass melting by means of this technology is the fact that the processes in the interior of the molten mass are still unknown. Under this aspect, the authors of the contribution under consideration present an overview of the inductive melting process for glasses in an inductor crucible developed at the Institute for Electrotechnology (Hanover, Federal Republic of Germany). A newly developed numerical model is presented in order to simulate the heat and mass transfer in a molten glass. This simulation enables a future optimization of the design of the inductor crucible and the melting process. The transient three-dimensional melting flow during the melting of glasses and oxides by means of the skull meeting process also can be simulated by the newly developed numerical model.

  14. The influence of melting processes and parameters on the structure and homogeneity of titanium-tantalum alloys

    International Nuclear Information System (INIS)

    Dunn, P.S.; Korzekwa, D.; Garcia, F.; Damkroger, B.K.; Avyle, J.A. Van Den; Tissot, R.G.

    1996-01-01

    Alloys of titanium with refractory metals are attractive materials for applications requiring high temperature strength and corrosion resistance. However, the widely different characteristics of the component elements have made it difficult to produce sound, compositionally homogeneous ingots using traditional melting techniques. This is particularly critical because the compositional ranges spanned by the micro- and macrosegregation in theses systems can easily encompass a number of microconstituents which are detrimental to mechanical properties. This paper presents the results of a study of plasma (PAM) and vacuum-arc (VAR) melting of a 60 wt% tantalum, 40 wt% titanium binary alloy. The structural and compositional homogeneity of PAM consolidated +PAM remelted, and PAM consolidated +VAR remelted ingots were characterized and compared using optical and electron microscopy and x-ray fluorescence microanalysis. Additionally, the effect of melting parameter, including melt rate and magnetic stirring, was studied. The results indicated the PAM remelting achieves more complete dissolution of the starting electrode, due to greater local superheat, than does VAR remelting. PAM remelting also produces a finer as solidified grain structure, due to the smaller molten pool and lower local solidification times. Conversely, VAR remelting produces an ingot with a more uniform macrostructure, due to the more stable movement of the solidification interface and more uniform material feed rate. Based on these results, a three-step process of PAM consolidation, followed by a PAM intermediate melt and a VAR final melt, has been selected for further development of the alloy and processing sequence

  15. Recent progress in the melt-process technique of high-temperature superconductors

    CERN Document Server

    Ikuta, H; Mizutani, U

    1999-01-01

    Recently, the performance of high-temperature super conductors prepared by the melt-process technique has been greatly improved. This progress was accomplished by the addition of Ag into the starting materials of the Sm-Ba-CuO $9 system, which prevents the formation of severe macro-sized cracks in the finished samples. The magnetic flux density trapped by this material has now reached 9 T at 25 K, which is comparable to the magnetic flux density produced by $9 ordinary superconducting magnets. The amount of magnetic flux density that can be trapped by the sample is limited by the mechanical strength rather than superconducting properties of the material. The increase in the mechanical $9 strength of the material is important both for further improvement of the material properties and for ensuring reliability of the material in practical applications. (20 refs).

  16. Effect of Build Angle on Surface Properties of Nickel Superalloys Processed by Selective Laser Melting

    Science.gov (United States)

    Covarrubias, Ernesto E.; Eshraghi, Mohsen

    2017-12-01

    Aerospace, automotive, and medical industries use selective laser melting (SLM) to produce complex parts through solidifying successive layers of powder. This additive manufacturing technique has many advantages, but one of the biggest challenges facing this process is the resulting surface quality of the as-built parts. The purpose of this research was to study the surface properties of Inconel 718 alloys fabricated by SLM. The effect of build angle on the surface properties of as-built parts was investigated. Two sets of sample geometries including cube and rectangular artifacts were considered in the study. It was found that, for angles between 15° and 75°, theoretical calculations based on the "stair-step" effect were consistent with the experimental results. Downskin surfaces showed higher average roughness values compared to the upskin surfaces. No significant difference was found between the average roughness values measured from cube and rectangular test artifacts.

  17. Effect of Build Angle on Surface Properties of Nickel Superalloys Processed by Selective Laser Melting

    Science.gov (United States)

    Covarrubias, Ernesto E.; Eshraghi, Mohsen

    2018-03-01

    Aerospace, automotive, and medical industries use selective laser melting (SLM) to produce complex parts through solidifying successive layers of powder. This additive manufacturing technique has many advantages, but one of the biggest challenges facing this process is the resulting surface quality of the as-built parts. The purpose of this research was to study the surface properties of Inconel 718 alloys fabricated by SLM. The effect of build angle on the surface properties of as-built parts was investigated. Two sets of sample geometries including cube and rectangular artifacts were considered in the study. It was found that, for angles between 15° and 75°, theoretical calculations based on the "stair-step" effect were consistent with the experimental results. Downskin surfaces showed higher average roughness values compared to the upskin surfaces. No significant difference was found between the average roughness values measured from cube and rectangular test artifacts.

  18. Reactive nanophase oxide additions to melt-processed high-{Tc} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Goretta, K.C.; Brandel, B.P.; Lanagan, M.T.; Hu, J.; Miller, D.J.; Sengupta, S. [Argonne National Lab., IL (United States); Parker, J.C.; Ali, M.N. [Nanophase Technologies Corp., Darien, IL (United States); Chen, Nan [Illinois Superconductor Corp., Evanston, IL (United States)

    1994-10-01

    Nanophase TiO{sub 2} and Al{sub 2}O{sub 3} powders were synthesized by a vapor-phase process and mechanically mixed with stoichiometric YBa{sub 2}Cu{sub 3}O{sub x} and TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} powders in 20 mole % concentrations. Pellets produced from powders with and without nanophase oxides were heated in air or O{sub 2} above the peritectic melt temperature and slow-cooled. At 4.2 K, the intragranular critical current density (J{sub c}) increased dramatically with the oxide additions. At 35--50 K, effects of the oxide additions were positive, but less pronounced. At 77 K, the additions decreased J{sub c}, probably because of inducing a depresion of the transition temperature.

  19. New Evidences on the Process Sensitivity of Some Renewable Blends Based on Starch considering Their Melt Rheological Properties

    Directory of Open Access Journals (Sweden)

    Doina Dimonie

    2016-01-01

    Full Text Available The degradability and processability of new renewable materials based on starch and PVOH were studied using the melt flow index (MFI method by measuring the melt rheological properties which depend not only on the extrusion conditions and material formulation but also on the macromolecule characteristics which can be modified by chemical degradation. These results were correlated with other material properties like color and cross-linking degree. The obtained results show that flowing in the melted state of the studied materials is accompanied by a second process of chains chemical degradation. It was observed that, at the same level of additivation, under identical extrusion conditions, the melted blends with corn starch as main component are highly mechanically sensitive and degrade mostly by chains scission and those with PVOH as major component are highly temperature sensitive and degrade mainly by cross-linking. The obtained results show also that each PVOH-starch blend requires particular formulation and individual windows of melt processing conditions. These results are a good proof that the MFI method is a good path to study the degradability and moldability of process sensitive polymeric materials like those based on starch and PVOH.

  20. Process Optimization and Microstructure Characterization of Ti6Al4V Manufactured by Selective Laser Melting

    Science.gov (United States)

    junfeng, Li; zhengying, Wei

    2017-11-01

    Process optimization and microstructure characterization of Ti6Al4V manufactured by selective laser melting (SLM) were investigated in this article. The relative density of sampled fabricated by SLM is influenced by the main process parameters, including laser power, scan speed and hatch distance. The volume energy density (VED) was defined to account for the combined effect of the main process parameters on the relative density. The results shown that the relative density changed with the change of VED and the optimized process interval is 55˜60J/mm3. Furthermore, compared with laser power, scan speed and hatch distance by taguchi method, it was found that the scan speed had the greatest effect on the relative density. Compared with the microstructure of the cross-section of the specimen at different scanning speeds, it was found that the microstructures at different speeds had similar characteristics, all of them were needle-like martensite distributed in the β matrix, but with the increase of scanning speed, the microstructure is finer and the lower scan speed leads to coarsening of the microstructure.

  1. Experimental Research on Selective Laser Melting AlSi10Mg Alloys: Process, Densification and Performance

    Science.gov (United States)

    Chen, Zhen; Wei, Zhengying; Wei, Pei; Chen, Shenggui; Lu, Bingheng; Du, Jun; Li, Junfeng; Zhang, Shuzhe

    2017-12-01

    In this work, a set of experiments was designed to investigate the effect of process parameters on the relative density of the AlSi10Mg parts manufactured by SLM. The influence of laser scan speed v, laser power P and hatch space H, which were considered as the dominant parameters, on the powder melting and densification behavior was also studied experimentally. In addition, the laser energy density was introduced to evaluate the combined effect of the above dominant parameters, so as to control the SLM process integrally. As a result, a high relative density (> 97%) was obtained by SLM at an optimized laser energy density of 3.5-5.5 J/mm2. Moreover, a parameter-densification map was established to visually select the optimum process parameters for the SLM-processed AlSi10Mg parts with elevated density and required mechanical properties. The results provide an important experimental guidance for obtaining AlSi10Mg components with full density and gradient functional porosity by SLM.

  2. Study of Raw Materials Treatment by Melting and Gasification Process in Plasma Arc Reactor

    Directory of Open Access Journals (Sweden)

    Peter KURILLA

    2010-12-01

    Full Text Available The world consumption of metals and energy has increased in last few decades and it is still increasing. Total volume production results to higher waste production. Raw material basis of majority metals and fossil fuels for energy production is more complex and current waste treatment has long term tendency. Spent power cells of different types have been unneeded and usually they are classified as dangerous waste. This important issue is the main topic of the thesis, in which author describes pyrometallurgical method for storage batteries – power cells and catalysts treatment. During the process there were tested a trial of spent NiMH, Li – ion power cells and spent copper catalysts with metal content treatment by melting and gasification process in plasma arc reactor. The synthetic gas produced from gasification process has been treated by cogenerations micro turbines units for energy recovery. The metal and slag from treatment process are produced into two separately phases and they were analyzing continually.

  3. Rates and processes of crystallization in on-axis and off-axis MOR basaltic melts

    Science.gov (United States)

    Zellmer, Georg F.; Dulski, Peter; Iizuka, Yoshiyuki; Perfit, Michael R.

    2012-12-01

    Residence times of olivine and plagioclase phenocrysts and xenocrysts in mid-ocean ridge (MOR) basaltic melts have been studied since the mid 1980s using geospeedometric techniques (i.e. using diffusion of major and trace elements) in order to constrain the processes of melt ascent and differentiation in this important magmatic setting. Residence times range from a few hours to several years, but potential links between these timescales and specific tectonomagmatic variables such as spreading rate and relative locations of eruption site and ridge axis have remained elusive. Here we demonstrate how incomplete chemical diffusion of Sr within plagioclase crystals from MOR basalts erupted in on- and off-axis settings on a number of ridges with variable spreading rates provide geospeedometric constraints. We combine electron probe microanalytical crystal maps with detailed laser ablation profiles of almost 70 plagioclase crystals from the fast spreading East Pacific Rise (EPR) at 9-10°N, the intermediate spreading Gorda and Juan de Fuca (JdF) ridges, and the ultraslow spreading Gakkel ridge to calculate crystal residence times. These range from a few days to several months. The scarcity of residence times exceeding years corroborates previous data indicating that most of the growth of plagioclase phenocrysts occurs within the conduit at the onset of and during eruption on the sea floor, and extends this result to the fast-spreading EPR. Further, statistical analysis is employed to show for the first time that residence times are systematically longer at slower spreading rates, in off-axis samples, and samples sourced from laterally distal axial melt lenses. Plagioclase textures and residence time variations appear to be linked to differences in the dynamics of late-stage, pre-eruptive magma storage and ascent in the different tectonomagmatic settings investigated. In the future, geospeedometric work on MOR samples will be required to assess if the effect of spreading

  4. Downstream processing from hot-melt extrusion towards tablets: A quality by design approach.

    Science.gov (United States)

    Grymonpré, W; Bostijn, N; Herck, S Van; Verstraete, G; Vanhoorne, V; Nuhn, L; Rombouts, P; Beer, T De; Remon, J P; Vervaet, C

    2017-10-05

    Since the concept of continuous processing is gaining momentum in pharmaceutical manufacturing, a thorough understanding on how process and formulation parameters can impact the critical quality attributes (CQA) of the end product is more than ever required. This study was designed to screen the influence of process parameters and drug load during HME on both extrudate properties and tableting behaviour of an amorphous solid dispersion formulation using a quality-by-design (QbD) approach. A full factorial experimental design with 19 experiments was used to evaluate the effect of several process variables (barrel temperature: 160-200°C, screw speed: 50-200rpm, throughput: 0.2-0.5kg/h) and drug load (0-20%) as formulation parameter on the hot-melt extrusion (HME) process, extrudate and tablet quality of Soluplus ® -Celecoxib amorphous solid dispersions. A prominent impact of the formulation parameter on the CQA of the extrudates (i.e. solid state properties, moisture content, particle size distribution) and tablets (i.e. tabletability, compactibility, fragmentary behaviour, elastic recovery) was discovered. The resistance of the polymer matrix to thermo-mechanical stress during HME was confirmed throughout the experimental design space. In addition, the suitability of Raman spectroscopy as verification method for the active pharmaceutical ingredient (API) concentration in solid dispersions was evaluated. Incorporation of the Raman spectroscopy data in a PLS model enabled API quantification in the extrudate powders with none of the DOE-experiments resulting in extrudates with a CEL content deviating>3% of the label claim. This research paper emphasized that HME is a robust process throughout the experimental design space for obtaining amorphous glassy solutions and for tabletting of such formulations since only minimal impact of the process parameters was detected on the extrudate and tablet properties. However, the quality of extrudates and tablets can be optimized

  5. Comparison of structure, morphology, and leach characteristics of multi-phase ceramics produced via melt processing and hot isostatic pressing

    Science.gov (United States)

    Dandeneau, Christopher S.; Hong, Tao; Brinkman, Kyle S.; Vance, Eric R.; Amoroso, Jake W.

    2018-04-01

    Melt processing of multi-phase ceramic waste forms offers potential advantages over traditional solid-state synthesis methods given both the prevalence of melters currently in use and the ability to reduce the possibility of airborne radionuclide contamination. In this work, multi-phase ceramics with a targeted hollandite composition of Ba1.0Cs0.3Cr1.0Al0.3Fe1.0Ti5.7O16 were fabricated by melt processing at 1675 °C and hot isostatic pressing (HIP) at 1250 and 1300 °C. X-ray diffraction analysis (XRD) confirmed hollandite as the major phase in all specimens. Zirconolite/pyrochlore peaks and weaker perovskite reflections were observed after melt processing, while HIP samples displayed prominent perovskite peaks and low-intensity zirconolite reflections. Melt processing produced specimens with large (>50 μm) well-defined hollandite grains, while HIP yielded samples with a more fine-grained morphology. Elemental analysis showed "islands" rich in Cs and Ti across the surface of the 1300 °C HIP sample, suggesting partial melting and partitioning of Cs into multiple phases. Photoemission data revealed multiple Cs 3d spin-orbit pairs for the HIP samples, with the lower binding energy doublets likely corresponding to Cs located in more leachable phases. Among all specimens examined, the melt-processed sample exhibited the lowest fractional release rates for Rb and Cs. However, the retention of Sr and Mo was greater in the HIP specimens.

  6. Anode process on platinum in CaCl2-CaO-based melt

    Directory of Open Access Journals (Sweden)

    K. V. Tatarenko

    2014-12-01

    Full Text Available Methods potentiostatic polarization and cyclic voltammetry obtained new data on the mechanism and kinetics of anodic processes on platinum in the molten CaCl2-KCl-CaO when 725–775 °C. Given thermodynamic values of potential difference probable total reactions in the range of the studied temperature. Using potentiostatic polarization and cyclic voltammetry obtained new data on the mechanism and kinetics of anodic process on platinum in the molten CaCl2-KCl-CaO when 725–775 °C thermodynamic assessment of the probability of occurrence total reactions during electrolysis melt on the basis of CaCl2-CaO using non-carbon anode. It is shown that at high current densities anodic process takes place mainly in the conditions of slow diffusion of electrically active particles to the anode, and at low densities (up to 10 mA/cm2 to their discharge to the atomic and lecular oxygen is preceded by a stage, which can be associated with adsorption of atoms of oxygen or with the formation of an oxide film on the surface of platinum. To detect the nature of this stage, further research is needed.

  7. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Daniel Koutny

    2018-02-01

    Full Text Available This paper deals with various selective laser melting (SLM processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material.

  8. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting

    Science.gov (United States)

    Palousek, David; Pantelejev, Libor; Hoeller, Christian; Pichler, Rudolf; Tesicky, Lukas; Kaiser, Jozef

    2018-01-01

    This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material. PMID:29443912

  9. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting.

    Science.gov (United States)

    Koutny, Daniel; Palousek, David; Pantelejev, Libor; Hoeller, Christian; Pichler, Rudolf; Tesicky, Lukas; Kaiser, Jozef

    2018-02-14

    This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material.

  10. Double Ion Implantation and Pulsed Laser Melting Processes for Third Generation Solar Cells

    Directory of Open Access Journals (Sweden)

    Eric García-Hemme

    2013-01-01

    Full Text Available In the framework of the third generation of photovoltaic devices, the intermediate band solar cell is one of the possible candidates to reach higher efficiencies with a lower processing cost. In this work, we introduce a novel processing method based on a double ion implantation and, subsequently, a pulsed laser melting (PLM process to obtain thicker layers of Ti supersaturated Si. We perform ab initio theoretical calculations of Si impurified with Ti showing that Ti in Si is a good candidate to theoretically form an intermediate band material in the Ti supersaturated Si. From time-of-flight secondary ion mass spectroscopy measurements, we confirm that we have obtained a Ti implanted and PLM thicker layer of 135 nm. Transmission electron microscopy reveals a single crystalline structure whilst the electrical characterization confirms the transport properties of an intermediate band material/Si substrate junction. High subbandgap absorption has been measured, obtaining an approximate value of 104 cm−1 in the photons energy range from 1.1 to 0.6 eV.

  11. Novel melt-processable nylon-6/inorganic fullerene-like WS2 nanocomposites for critical applications

    International Nuclear Information System (INIS)

    Naffakh, Mohammed; Marco, Carlos; Gomez, Marian A.; Jimenez, Ignacio

    2011-01-01

    Highlights: → Environmentally-friendly IF-WS 2 is used to produce advanced nylon-6 NCPs. → Novel IF-WS 2 improves the thermal and mechanical performances of nylon-6. → IF-WS 2 is effective in reducing the friction coefficient of nylon-6. → New insights into polymorphic behaviour of nylon-6 in NCPs. - Abstract: Environmentally-friendly inorganic fullerene-like tungsten disulfide nanoparticles (IF-WS 2 ) were used to produce new nylon-6 nanocomposites. The addition of IF-WS 2 is an effective way to improve the thermal, mechanical and tribological properties of polymeric materials. In the present work, the nylon-6/IF-WS 2 nanocomposites were processed by advantageously traditional melt processing technique. The IF-WS 2 nanoparticles do not require exfoliation or modification, making it possible to obtain stronger and lighter materials without the complexity and processing cost associated with these treatments. The thermo-oxidative stability of nylon-6/IF-WS 2 nanocomposites was studied using thermogravimetric analysis. The thermal behaviour and crystalline phase transition of nylon-6 were investigated using DSC and time-resolved synchrotron X-ray diffraction in order to obtain a picture describing the physico-chemical transformation of nylon-6 molecules from the non-ordered state to the ordered state. Dynamic mechanical analysis and tribological tests had been carried out to evaluate the effect of IF-WS 2 on the mechanical performance, friction and wear behaviour of nylon-6/IF-WS 2 nanocomposites. The results showed that significant improvement can be achieved in the thermal, mechanical and tribological properties of nylon-6 nanocomposites. In addition, the incorporation of IF-WS 2 nanoparticles has shown to be an effective way to promote the crystallization process of nylon-6, which also influences the crystalline transformation of nylon-6 (i.e. Brill transition) observed during both cooling and heating processes.

  12. Influence of the oxygen partial pressure on the phase evolution during Bi-2212 wire melt processing

    CERN Document Server

    Scheuerlein, C.; Rikel, M.O.; Kadar, J.; Doerrer, C.; Di Michiel, M.; Ballarino, A.; Bottura, L.; Jiang, J.; Kametani, F.; Hellstrom, E.E.; Larbalestier, D.C.

    2016-01-01

    We have studied the influence of the oxygen partial pressure pO2 up to 5.5 bar on the phase changes that occur during melt processing of a state-of-the-art Bi-2212 multifilamentary wire. Phase changes have been monitored in situ by high energy synchrotron X-ray diffraction (XRD). We found that the stability of Bi-2212 phase is reduced with increasing pO2. For pO2>1 bar a significant amount of Bi-2212 phase decomposes upon heating in the range 400 to 650 °C. The extent of decomposition strongly increases with increasing pO2, and at pO2=5.5 bar Bi-2212 decomposes completely in the solid state. Textured Bi-2212 can be formed during solidification when pO2 is reduced to 0.45 bar when the precursor is molten. Since the formation of current limiting second phases is very sensitive to pO2 when it exceeds 1 bar, we recommend to reduce the oxygen partial pressure below the commonly used pO2=1 bar, in order to increase the pO2 margins and to make the overpressure process more robust.

  13. An integrated approach of topology optimized design and selective laser melting process for titanium implants materials.

    Science.gov (United States)

    Xiao, Dongming; Yang, Yongqiang; Su, Xubin; Wang, Di; Sun, Jianfeng

    2013-01-01

    The load-bearing bone implants materials should have sufficient stiffness and large porosity, which are interacted since larger porosity causes lower mechanical properties. This paper is to seek the maximum stiffness architecture with the constraint of specific volume fraction by topology optimization approach, that is, maximum porosity can be achieved with predefine stiffness properties. The effective elastic modulus of conventional cubic and topology optimized scaffolds were calculated using finite element analysis (FEA) method; also, some specimens with different porosities of 41.1%, 50.3%, 60.2% and 70.7% respectively were fabricated by Selective Laser Melting (SLM) process and were tested by compression test. Results showed that the computational effective elastic modulus of optimized scaffolds was approximately 13% higher than cubic scaffolds, the experimental stiffness values were reduced by 76% than the computational ones. The combination of topology optimization approach and SLM process would be available for development of titanium implants materials in consideration of both porosity and mechanical stiffness.

  14. Regularities of the chlorination process of phosphates and tungstates of some actinide and fission elements in chloride melts

    International Nuclear Information System (INIS)

    Kryukova, A.I.; Chernikov, A.A.; Skiba, O.V.; Kazantsev, G.N.

    1988-01-01

    Results of kinetic studies of chlorination process of crystal phosphates and tungstates of uranium, cerium, zirconium, plutonium by vapours of carbon tetrachloride in the melts of alkali element chlorides at of 973-1073 K have been analyzed. Mathematical models for the process description are suggested. Analysis of adequate models of regression type permitted to solve the problem of statistical evaluation of affecting factors and to predict within factor space studied the conditions for the optimal process course

  15. Microstructure of reaction zone in WCp/duplex stainless steels matrix composites processing by laser melt injection

    NARCIS (Netherlands)

    Do Nascimento, A. M.; Ocelik, V.; Ierardi, M. C. F.; De Hosson, J. Th. M.

    2008-01-01

    The laser melt injection (LMI) process has been used to create a metal matrix composite consisting of 80gm sized multi-grain WC particles embedded in three cast duplex stainless steels. The microstruture was investigated by scanning electron microscopy with integrated EDS and electron back-scatter

  16. submitter Comparison of microstructure, second phases and texture formation during melt processing of Bi-2212 mono- and multifilament wires

    CERN Document Server

    Kadar, J; Rikel, MO; Di Michiel, M; Huang, Y

    2016-01-01

    Based on simultaneous in situ high energy synchrotron micro-tomography and x-ray diffraction (XRD) measurements we compare the microstructural changes and the formation of second phases and texture during the processing of Bi-2212 round wires with 15 μm filament diameter (multifilament) and 650 μm filament diameter (monofilament) fabricated using identical Bi-2212 precursor. The monofilament tomograms show in unprecedented detail how the distributed porosity agglomerates well before Bi-2212 melting decomposition to form lenticular voids that completely interrupt the filament connectivity along the wire axis. When the Bi-2212 phase completely melts connectivity in the axial wire direction is established via the changes in the void morphology from the lenticular voids to bubbles that remain when Bi-2212 crystallises out of the melt. By measuring the attenuation of the monochromatic x-ray beam, the associated Bi-2212 mass density changes have been monitored during the entire heat cycle. The XRD results reveal ...

  17. Melt processing of the Bi2Sr2CaCu2Oy superconductor in oxygen and argon atmospheres

    International Nuclear Information System (INIS)

    Holesinger, T.G.; Miller, D.J.; Chumbley, L.S.

    1992-08-01

    Solidification and subsequent annealing of Bi 2 Sr 2 CaCu 2 O y (2212) in oxygen and argon atmospheres were investigated in order to identify alternative processing routes for controlling microstructures and superconducting properties. In addition to 2212, several other phases formed on cooling in O 2 and did not disappear upon subsequent annealing. Crystallization in Ar resulted in a divorced eutetic structure of Bi 2 Sr 3-x Ca x O y and Cu 2 O/CuO. The superconductor was formed on subsequent anneals. Samples melted in Ar and then annealed generally possessed a more uniform microstructure compared with samples that were melted in oxygen and annealed. Compositional measurements of the 2212 phase suggest that CaO segregation in the melt may be minimized with an overall composition such as Bi 2.15 Sr 2 Ca 0.85 Cu 2 O y

  18. Mechanical and physical properties of AlSi10Mg processed through selective laser melting

    Science.gov (United States)

    Raus, A. A.; Wahab, M. S.; Ibrahim, M.; Kamarudin, K.; Ahmed, Aqeel; Shamsudin, S.

    2017-04-01

    In the past few decade, Additive Manufacturing (AM) has become popular and substantial to manufacture direct functional parts in varieties industrial applications even in very challenging like aerospace, medical and manufacturing sectors. Selective Laser Melting (SLM) is one of the most efficient technique in the additive Manufacturing (AM) which able to manufacture metal component directly from Computer Aided Design (CAD) file data. Accuracy, mechanical and physical properties are essentials requirement in order to meet the demand of those engineering components. In this paper, the mechanical properties of SLM manufactured AlSi10Mg samples such as hardness, tensile strength, and impact toughness are investigated and compared to conventionally high pressure die cast A360 alloy. The results exposed that the hardness and the yield strength of AlSi10Mg samples by SLM were increased by 42% and 31% respectively to those of conventionally high pressure die cast A360 alloy even though without comprehensive post processing methods. It is also discovered that AlSi10Mg parts fabricated by SLM achieved the highest density of 99.13% at the best setting parameters from a previous study of 350 watts laser power, 1650 mm/s scanning speed and hatching distance 0.13 mm.

  19. Numerical simulation of heat transfer and melting of Fe-based powders in SLM processing

    Science.gov (United States)

    Ankudinov, V.; Gordeev, G. A.; Krivilyov, M. D.

    2017-04-01

    Modelling of selective laser melting (SLM) of Fe and stainless steel powders has been performed to analyze unsteady heat transfer in a porous medium under conditions of rapid phase transformations. The pulsed laser heat source develops high temperature gradients that lead to large solidification velocities, which can be used in acquisition of complex microstructures in SLM manufacturing. First, the effective thermal conductivity as a function of the local porosity which is a dynamically varying parameter in SLM was evaluated numerically. It showed a high role of heat transfer through the gas phase in powders with low thermal conductivity, i.e. in stainless steel. At the porosity 65% and above, the mechanism of heat transfer drastically changed and a linear dependence of thermal conductivity on porosity frequently used in literature becomes incorrect. Second, the obtained dependence was accounted for modelling of thermal fields and powder consolidation in the powder bed. The results of simulation agree well with the obtained experimental data and show the importance of correct dynamical evaluation of the thermophysical properties in SLM processes.

  20. Polymer-melt interactions during casting formation in the lost foam process

    Energy Technology Data Exchange (ETDEWEB)

    Shivkumar, S.; Yao, X.; Makhlouf, M. [Worcester Polytechnic Inst., MA (United States). Dept. of Mechanical Engineering

    1995-07-01

    The lost foam casting process utilizes injection modeled polymeric foam patterns for the production of metallic components. Foamed polymer patterns of the desired shape are coated with a water-based refractory slurry, dried and embedded in unbonded sand. Molten metal is poured directly on the coated polymer. The polymer undergoes thermal degradation and is gradually replaced by the liquid metal to yield the casting after solidification. Expanded polystyrene (EPS) is the most common pattern material used in commercial practice. The use of EPS patterns with ferrous castings may result in the formation of carbonaceous defects in the casting. Consequently, polymethylmethacrylate (PMMA) and copolymers of EPS and PMMA have been developed for ferrous castings. The thermal degradation of the foamed pattern results in the formation of gaseous degradation products and of a partially depolymerized viscous residue. The fraction of viscous residue increased with temperature and is essentially constant above about 650 C. During the filling of EPS patterns, nearly 60% of the polymer is converted to the viscous residue and 40% is transformed to gaseous products. In the case of PMM, almost 60% of the polymer undergoing degradation at the metal front is transformed to gaseous products. The melt flow velocity during the filling of the mold generally increases with temperature.

  1. In vitro and in vivo evaluation of floating riboflavin pellets developed using the melt pelletization process.

    Science.gov (United States)

    Hamdani, J; Goole, J; Moës, A J; Amighi, K

    2006-10-12

    Floating pellets were prepared using the melt pelletization process in a Mi-Pro high shear mixer (Pro-C-epT, Belgium). Formulations were based on a mixture of Compritol and Precirol as meltable binders and on the use of sodium bicarbonate and tartaric acid as gas-generating agents. Good floating abilities were obtained by using the gas-generating agents in both the inner matrix and the outer coating layer of the pellets. In vitro evaluation of floating capability was performed both by using the resultant weight apparatus and by counting floating pellets at the surface of beakers containing 0.1N HCl solution, in vivo evaluation of floating pellets capabilities was also performed. Riboflavin-containing floating pellets (FRF) were administered orally to nine healthy volunteers versus non-floating pellets (NFRF). Volunteers were divided in two groups, fasted group (n=4) 729 kcal and fed group (n=5) 1634 kcal as the total calorie intake on the testing day. An increase of urinary excretion of riboflavin was observed when the volunteers were dosed with the floating pellets, especially after feeding. As riboflavin has a narrow window of absorption in the upper part of small intestine, this phenomenon could be attributable to the gastric retention of floating pellets.

  2. Influence of Annealing on Mechanical Properties of Al-20Si Processed by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Pan Ma

    2014-01-01

    Full Text Available The microstructure and mechanical properties of Al-20Si produced by selective laser melting (SLM are investigated for different heat treatment conditions. As a result of the high cooling rate during processing, the as-built SLM material displays a microstructure consisting of a supersaturated Al(Si solid solution along with heavily refined eutectic Si and Si particles. The Si particles become coarser, and the eutectic Si gradually changes its morphology from fibrous to plate-like shape with increasing annealing temperature. The microstructural variations occurring during heat treatment significantly affect the mechanical behavior of the samples. The yield and ultimate strengths decrease from 374 and 506 MPa for the as-built SLM material to 162 and 252 MPa for the sample annealed at 673 K, whereas the ductility increases from 1.6 to 8.7%. This offers the possibility to tune microstructure and corresponding properties of the Al-20Si SLM parts to meet specific requirements.

  3. Development Algorithm of the Technological Process of Manufacturing Gas Turbine Parts by Selective Laser Melting

    Science.gov (United States)

    Sotov, A. V.; Agapovichev, A. V.; Smelov, V. G.; Kyarimov, R. R.

    2018-01-01

    The technology of the selective laser melting (SLM) allows making products from powders of aluminum, titanium, heat-resistant alloys and stainless steels. Today the use of SLM technology develops at manufacture of the functional parts. This in turn requires development of a methodology projection of technological processes (TP) for manufacturing parts including databases of standard TP. Use of a technique will allow to exclude influence of technologist’s qualification on made products quality, and also to reduce labor input and energy consumption by development of TP due to use of the databases of standard TP integrated into a methodology. As approbation of the developed methodology the research of influence of the modes of a laser emission on a roughness of a surface of synthesized material was presented. It is established that the best values of a roughness of exemplars in the longitudinal and transversal directions make 1.98 μm and 3.59 μm respectively. These values of a roughness were received at specific density of energy 6.25 J/mm2 that corresponds to power and the speed of scanning of 200 W and 400 mm/s, respectively, and a hatch distance of 0.08 mm.

  4. Development of a Novel Melt Spinning-Based Processing Route for Oxide Dispersion-Strengthened Steels

    Science.gov (United States)

    Hong, Zuliang; Morrison, Alasdair P. C.; Zhang, Hongtao; Roberts, Steve G.; Grant, Patrick S.

    2018-02-01

    Melt spinning of an Fe-5Y and Fe-1Y-1Ti (wt pct) alloy produced a relatively uniform spatial distribution of Y and Ti in solid solution and ribbons with consistent yield (> 60 pct by weight), fast processing time ( 100 g feedstock material), and repeatability. Heat treatment in the presence of Fe2O3 as an oxygen source (Rhines pack method) at 973 K validated the potential of forming consolidated to bulk using the field-assisted sintering technique (FAST) incorporating nano-sized Fe3O4 powder as the oxygen source. After FAST at 1273 K, 50 MPa, and 30 minutes, a comparatively high number density of sub-micron Y and/or Ti-rich oxides were developed. Further formation of fine-scale oxides took place during post-FAST annealing, resulting in an approximate 20 pct increase in hardness at temperatures below 573 K, but with a reduced hardening effect above 673 K due to a small fraction of persistent porosity and mechanically weak prior ribbon boundaries that were decorated with Ti-rich oxides.

  5. Selective Laser Melting Produced Ti-6Al-4V: Post-Process Heat Treatments to Achieve Superior Tensile Properties

    Directory of Open Access Journals (Sweden)

    Gerrit M. Ter Haar

    2018-01-01

    Full Text Available Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α’/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples.

  6. Investigating the Use of Polymeric Binders in Twin Screw Melt Granulation Process for Improving Compactibility of Drugs.

    Science.gov (United States)

    Batra, Amol; Desai, Dipen; Serajuddin, Abu T M

    2017-01-01

    Traditionally, the melt granulation for pharmaceutical products was performed at low temperature (granulators using low-melting waxy binders, and tablets produced using such granules were not amenable to large-scale manufacturing. The situation has changed in recent years by the use of twin screw extruder where the processing temperature could be increased to as high as 180°C and polymers with high T g could be used as binders. In this study, different polymeric binders were screened for their suitability in improving compactibility of 2 drugs, metformin hydrochloride and acetaminophen, by twin screw melt granulation. Processing temperatures for the 2 drugs were set at 180°C and 130°C, respectively. Screw configuration, screw speed, and feed rate were optimized such that all polymeric binders used produced granules. Several hydroxypropyl cellulose, hydroxypropyl methylcellulose, polyvinylpyrrolidone, and methacrylate-based polymers, including Klucel ® EXF, Eudragit ® EPO, and Soluplus ® , demonstrated good tablet tensile strength (>2 MPa) when granules were produced using only 10% wt/wt polymer concentration. Certain polymers provided acceptable compactibility even at 5% wt/wt. Thus, twin screw melt granulation process may be used with different polymers at a wide range of temperature. Due to low excipient concentration, this granulation method is especially suitable for high-dose tablets. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  7. Selective Laser Melting Produced Ti-6Al-4V: Post-Process Heat Treatments to Achieve Superior Tensile Properties.

    Science.gov (United States)

    Ter Haar, Gerrit M; Becker, Thorsten H

    2018-01-17

    Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α'/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples.

  8. Pretreatment of Process Condensate with Ammonia Degassing in CAN Fertilizer Production

    Directory of Open Access Journals (Sweden)

    Leaković, S.

    2011-10-01

    Full Text Available In the production process of calcium ammonium nitrate (CAN fertilizer, process-condensate is generated with a high content of ammonium nitrogen. Such high mass concentration of ammonium nitrogen (approximately 2 g L-1 significantly burdens the operation of the wastewater treatment plant, where the process condensate is treated by method of ion exchange. At CAN 1 Plant, a degassing system for process condensate was built. After pretreatment, the concentration of ammonium nitrogen in the process condensate was reduced to less than 500 mg L-1.Before upgrading with degassing system, the process condensate from CAN 1 Plant was collected in tank TK 17 301, from which it was pumped to the wastewater treatment plant to be treated by the method of ion exchange. When CAN 1 Plant is in normal operation, 10 m3h-1 of process condensate is formed with pH around 10, and temperatures around 50 °C. The degassing system of process condensate consists of a new tank, TK 17 504, which is connected with new pipeline to the tank TK 17 301. The process condensate input was transferred from the old to the new tank, TK 17 504. A new pump was installed for regulation of process condensate and bursting above the condensate level.Additional stimulation for ammonia degassing followed, after the return of 12 bar steam condensate into the tank TK 17 504. Consequently, the process condensate temperature increased to 80 C. Degassed ammonia is introduced into the existing system for washing gases and returns into the process of fertilizer production.By degassing ammonia from the process condensate at CAN 1 Plant, 10.7 kg h-1of ammonia returns into the fertilizer production process.Additionally, there has been an improved performance of the wastewater treatment plant, so that in December 2010, the volume of treated wastewater was almost 80 000 m3 which is an increase of 86 %.

  9. January 2016 West Antarctic Melt Event: Large Scale Forcing and Local Processes

    Science.gov (United States)

    Bromwich, D. H.; Nicolas, J. P.

    2017-12-01

    A huge surface melt event occurred in January 2016 that affected a large portion of the Ross Ice Shelf and adjacent parts of Marie Byrd Land of West Antarctica. It coincided with one of the strongest El Niño events on record in the tropical Pacific Ocean. The El Niño teleconnection pattern in the South Pacific Ocean favors the advection of warm, moist air into the western part of West Antarctica. At the same time strong westerly winds over the Southern Ocean, captured by the Southern Annular Mode or SAM, were strong before, during, and after the melting episode, and these tend to limit the transport of marine air into the Ross Ice Shelf region. This prominent melt event demonstrates that extensive melting can happen regardless of the state of the SAM when the El Niño forcing is strong. Furthermore, because climate models project more frequent major El Niños in the future with a warming climate, we can expect more major surface melt events in West Antarctica as the 21st century unfolds. The melting event occurred in part of the West Antarctic Ice Sheet that the ice sheet modeling study of DeConto and Pollard (2016) suggests is prone to collapse as a result of extreme greenhouse warming. This melt event happened while an important field campaign, the Atmospheric Radiation Measurement West Antarctic Radiation Experiment (AWARE), was ongoing in central West Antarctica. The observations collected during this campaign provided unique insight into some of the physical mechanisms governing surface melting in this otherwise data-sparse region. In particular, these observations highlighted the presence of low-level liquid-water clouds, which aided the radiative heating of the snow surface from both shortwave and longwave radiation, reminiscent of summer melting conditions in Greenland. The resulting large flux of energy into the snow pack was reflected in increased satellite microwave brightness temperatures that were used to follow the evolution of the widespread

  10. Single phase melt processed powellite (Ba,Ca)MoO4 for the immobilization of Mo-rich nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, Kyle [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Fox, Kevin [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Marra, James [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Reppert, Jason [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Crum, Jarrod [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tang, Ming [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2013-02-01

    Cs is one of the more problematic fission product radionuclides to immobilize due to its high volatility at elevated temperatures, ability to form water soluble compounds, and its mobility in many host materials. The hollandite structure is a promising crystalline host for Cs immobilization and has been traditionally fabricated by solid state sintering methods. This study presents the structure and performance of Ba{sub 1.0}Cs{sub 0.3}A{sub 2.3}Ti{sub 5.7}O{sub 16}; A = Cr, Fe, Al hollandite fabricated by melt processing. Melt processing is considered advantageous given that melters are currently in use for High Level Waste (HLW) vitrification in several countries. This work details the impact of Cr additions that were demonstrated to i) promote the formation of a Cs containing hollandite phase and ii) maintain the stability of the hollandite phase in reducing conditions anticipated for multiphase waste form processing.

  11. Microstructural and mechanical approaches of the selective laser melting process applied to a nickel-base superalloy

    International Nuclear Information System (INIS)

    Vilaro, T.; Colin, C.; Bartout, J.D.; Nazé, L.; Sennour, M.

    2012-01-01

    Highlights: ► We examine the as-fabricated microstructure of the Nimonic 263 processed by selective laser melting. ► We optimized heat treatments to modify the microstructure and improve the mechanical properties. ► We tested through tensile tests the various microstructures in order to compare the effects of the heat treatments. - Abstract: This article aims at presenting the Nimonic 263 as-processed microstructure of the selective laser melting which is an innovative process. Because the melting pool is small and the scanning speed of the laser beam is relatively high, the as-processed microstructure is out-of-equilibrium and very typical to additive manufacturing processes. To match the industrial requirement, the microstructures are modified through heat treatments in order to either produce precipitation hardening or relieve the thermal stresses. Tensile tests at room temperature give rise to high mechanical properties close or above those presented by Wang et al. . However, it is noted a strong anisotropy as a function of the building direction of the samples because of the columnar grain growth.

  12. Characterization of frictional melting processes in subduction zone faults by trace element and isotope analyses

    Science.gov (United States)

    Ishikawa, T.; Ujiie, K.

    2017-12-01

    Pseudotachylytes found in exhumed accretionary complexes, which are considered to be formed originally at seismogenic depths, are of great importance for elucidating frictional melting and concomitant dynamic weakening of the fault during earthquake in subduction zones. However, fluid-rich environment of the subduction zone faults tends to cause extensive alteration of the pseudotachylyte glass matrix in later stages, and thus it has been controversial that pseudotachylytes are rarely formed or rarely preserved. Chemical analysis of the fault rocks, especially on fluid-immobile trace elements and isotopes, can be a useful means to identify and quantify the frictional melting occurred in subduction zone faults. In this paper, we report major and trace element and Sr isotope compositions for pseudotachylyte-bearing dark veins and surrounding host rocks from the Mugi area of the Shimanto accretionary complex (Ujiie et al., J. Struct. Geol. 2007). Samples were collected from a rock chip along the microstructure using a micro-drilling technique, and then analyzed by ICP-MS and TIMS. Major element compositions of the dark veins showed a clear shift from the host rock composition toward the illite composition. The dark veins, either unaltered or completely altered, were also characterized by extreme enrichment in some of the trace elements such as Ti, Zr, Nb and Th. These results are consistent with disequilibrium melting of the fault zone. Model calculations revealed that the compositions of the dark veins can be produced by total melting of clay-rich matrix in the source rock, leaving plagioclase and quartz grains almost unmolten. The calculations also showed that the dark veins are far more enriched in melt component than that expected from the source rock compositions, suggesting migration and concentration of frictional melt during the earthquake faulting. Furthermore, Sr isotope data of the dark veins implied the occurrence of frictional melting in multiple stages

  13. A numerical study of zone-melting process for the thermoelectric material of Bi2Te3

    Science.gov (United States)

    Chen, W. C.; Wu, Y. C.; Hwang, W. S.; Hsieh, H. L.; Huang, J. Y.; Huang, T. K.

    2015-06-01

    In this study, a numerical model has been established by employing a commercial software; ProCAST, to simulate the variation/distribution of temperature and the subsequent microstructure of Bi2Te3 fabricated by zone-melting technique. Then an experiment is conducted to measure the temperature variation/distribution during the zone-melting process to validate the numerical system. Also, the effects of processing parameters on crystallization microstructure such as moving speed and temperature of heater are numerically evaluated. In the experiment, the Bi2Te3 powder are filled into a 30mm diameter quartz cylinder and the heater is set to 800°C with a moving speed 12.5 mm/hr. A thermocouple is inserted in the Bi2Te3 powder to measure the temperature variation/distribution of the zone-melting process. The temperature variation/distribution measured by experiment is compared to the results of numerical simulation. The results show that our model and the experiment are well matched. Then the model is used to evaluate the crystal formation for Bi2Te3 with a 30mm diameter process. It's found that when the moving speed is slower than 17.5 mm/hr, columnar crystal is obtained. In the end, we use this model to predict the crystal formation of zone-melting process for Bi2Te3 with a 45 mm diameter. The results show that it is difficult to grow columnar crystal when the diameter comes to 45mm.

  14. A numerical study of zone-melting process for the thermoelectric material of Bi2Te3

    International Nuclear Information System (INIS)

    Chen, W C; Wu, Y C; Hwang, W S; Hsieh, H L; Huang, J Y; Huang, T K

    2015-01-01

    In this study, a numerical model has been established by employing a commercial software; ProCAST, to simulate the variation/distribution of temperature and the subsequent microstructure of Bi 2 Te 3 fabricated by zone-melting technique. Then an experiment is conducted to measure the temperature variation/distribution during the zone-melting process to validate the numerical system. Also, the effects of processing parameters on crystallization microstructure such as moving speed and temperature of heater are numerically evaluated. In the experiment, the Bi 2 Te 3 powder are filled into a 30mm diameter quartz cylinder and the heater is set to 800°C with a moving speed 12.5 mm/hr. A thermocouple is inserted in the Bi 2 Te 3 powder to measure the temperature variation/distribution of the zone-melting process. The temperature variation/distribution measured by experiment is compared to the results of numerical simulation. The results show that our model and the experiment are well matched. Then the model is used to evaluate the crystal formation for Bi 2 Te 3 with a 30mm diameter process. It's found that when the moving speed is slower than 17.5 mm/hr, columnar crystal is obtained. In the end, we use this model to predict the crystal formation of zone-melting process for Bi 2 Te 3 with a 45 mm diameter. The results show that it is difficult to grow columnar crystal when the diameter comes to 45mm. (paper)

  15. Influence of Process Parameters on the Quality of Aluminium Alloy EN AW 7075 Using Selective Laser Melting (SLM)

    Science.gov (United States)

    Kaufmann, N.; Imran, M.; Wischeropp, T. M.; Emmelmann, C.; Siddique, S.; Walther, F.

    Selective laser melting (SLM) is an additive manufacturing process, forming the desired geometry by selective layer fusion of powder material. Unlike conventional manufacturing processes, highly complex parts can be manufactured with high accuracy and little post processing. Currently, different steel, aluminium, titanium and nickel-based alloys have been successfully processed; however, high strength aluminium alloy EN AW 7075 has not been processed with satisfying quality. The main focus of the investigation is to develop the SLM process for the wide used aluminium alloy EN AW 7075. Before process development, the gas-atomized powder material was characterized in terms of statistical distribution: size and shape. A wide range of process parameters were selected to optimize the process in terms of optimum volume density. The investigations resulted in a relative density of over 99%. However, all laser-melted parts exhibit hot cracks which typically appear in aluminium alloy EN AW 7075 during the welding process. Furthermore the influence of processing parameters on the chemical composition of the selected alloy was determined.

  16. Investigation of the Dynamic Melting Process in a Thermal Energy Storage Unit Using a Helical Coil Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Xun Yang

    2017-08-01

    Full Text Available In this study, the dynamic melting process of the phase change material (PCM in a vertical cylindrical tube-in-tank thermal energy storage (TES unit was investigated through numerical simulations and experimental measurements. To ensure good heat exchange performance, a concentric helical coil was inserted into the TES unit to pipe the heat transfer fluid (HTF. A numerical model using the computational fluid dynamics (CFD approach was developed based on the enthalpy-porosity method to simulate the unsteady melting process including temperature and liquid fraction variations. Temperature measurements using evenly spaced thermocouples were conducted, and the temperature variation at three locations inside the TES unit was recorded. The effects of the HTF inlet parameters were investigated by parametric studies with different temperatures and flow rate values. Reasonably good agreement was achieved between the numerical prediction and the temperature measurement, which confirmed the numerical simulation accuracy. The numerical results showed the significance of buoyancy effect for the dynamic melting process. The system TES performance was very sensitive to the HTF inlet temperature. By contrast, no apparent influences can be found when changing the HTF flow rates. This study provides a comprehensive solution to investigate the heat exchange process of the TES system using PCM.

  17. First results of in-can microwave processing experiments for radioactive liquid wastes at the Oak Ridge National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    White, T.L.; Youngblood, E.L.; Berry, J.B.; Mattus, A.J.

    1990-01-01

    The Oak Ridge National Laboratory (ORNL) Waste Handling and Packaging Plant is developing a microwave process to reduce and solidify remote-handled transuranic (RH-TRU) liquids and sludges presently stored in large tanks at ORNL. Testing has recently begun on an in drum microwave process using nonradioactive RH-TRU surrogates. The microwave process development effort has focused on an in-drum process to dry the RH-TRU liquids and sludges in the final storage container and then melt the salt residues to form a solid monolith. A 1/3-scale proprietary microwave applicator was designed, fabricated, and tested to demonstrate the essential features of the microwave design and to provide input into the design of the full-scale applicator. Conductivity cell measurements suggest that the microwave energy heats near the surface of the surrogate over a wide range of temperatures. The final wasteform meets the waste acceptance criteria for the Waste Isolation Pilot Plant, a federal repository for defense transuranic wastes near Carlsbad, New Mexico. 7 refs., 3 figs., 1 tab.

  18. First results of in-can microwave processing experiments for radioactive liquid wastes at the Oak Ridge National Laboratory

    International Nuclear Information System (INIS)

    White, T.L.; Youngblood, E.L.; Berry, J.B.; Mattus, A.J.

    1990-01-01

    The Oak Ridge National Laboratory (ORNL) Waste Handling and Packaging Plant is developing a microwave process to reduce and solidify remote-handled transuranic (RH-TRU) liquids and sludges presently stored in large tanks at ORNL. Testing has recently begun on an in drum microwave process using nonradioactive RH-TRU surrogates. The microwave process development effort has focused on an in-drum process to dry the RH-TRU liquids and sludges in the final storage container and then melt the salt residues to form a solid monolith. A 1/3-scale proprietary microwave applicator was designed, fabricated, and tested to demonstrate the essential features of the microwave design and to provide input into the design of the full-scale applicator. Conductivity cell measurements suggest that the microwave energy heats near the surface of the surrogate over a wide range of temperatures. The final wasteform meets the waste acceptance criteria for the Waste Isolation Pilot Plant, a federal repository for defense transuranic wastes near Carlsbad, New Mexico. 7 refs., 3 figs., 1 tab

  19. Microstructure and tensile properties of Ti-6Al-4V alloys manufactured by selective laser melting with optimized processing parameters

    Science.gov (United States)

    Wang, L.; Ma, C.; Huang, J.; Ding, H. Y.; Chu, M. Q.

    2017-11-01

    Selective laser melting (SLM) is a precise additive manufacturing process that the metallic powders without binder are melted layer by layer to complex components using a high bright fiber laser. In the paper, Ti-6Al-4V alloy was fabricated by SLM and its microstructure and mechanical properties were investigated in order to evaluate the SLM process. The results show that the microstructure exists anisotropy between the horizontal and vertical section due to the occurrence of epitaxial growth, and the former microstructure seems equal-axis and the latter is column. Moreover, there is little difference in tensile test between the horizontal and vertical sections. Furthermore, the tensile properties of fabricated Ti-6Al-4V alloy by SLM are higher than the forged standard ones. However, the fatigue results show that there are some scatters, which need further investigation to define the fatigue initiation.

  20. SIMULATING OF A HEAT TRANSFER PROCESS IN ROAD STRUCTURE EQUIPPED WITH A SNOW MELTING SYSTEM

    OpenAIRE

    V. P. Podolsky

    2009-01-01

    A non-stationary mathematical model of a heat transfer in the road structure equipped with the embedded hydraulic system preventing the formation of snow and ice coating of the road surface is numerically investigated and formu-lated. The mathematical model allows designing the energy saving modes of operating for snow melting systems taking into account various mechanical and meteorological factors.

  1. Laser melt injection of ceramic particles in metals : Processing, microstructure and properties

    NARCIS (Netherlands)

    Ocelík, V.; De Hosson, J.Th.M.

    2010-01-01

    The objective of this paper is to present an overview of the possibilities of the laser melt injection (LMI) methodology to enhance the surface of light-weighted metals by adding hard ceramic particles in the top layer, with the aim to enhance the wear resistance and to increase the hardness. In

  2. Melt compositions and processes in the kimberlite provience of southern West Greenland

    DEFF Research Database (Denmark)

    Pilbeam, Llewellyn; Nielsen, Troels; Waight, Tod Earle

    2011-01-01

    The kimberlite province of southern West Greenland (600- 560Ma) comprises kimberlite sensu stricto on the Archean craton and aillikites on the paleoproterzoic sheild to the North. Carbonatite melt and xenocrystic olivine dominate the kimberlite sensu stricto occurrences of the Manitsoq region [1]...

  3. Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

    International Nuclear Information System (INIS)

    Zou, Wei; Chen, Rongyuan; Zhang, Haichen; Qu, Jinping

    2016-01-01

    Poly (lactic acid) (PLA)/Poly (propylene carbonate) (PPC) blends were prepared by vane extruder which is a type of novel polymer processing extruder based on elongation force field. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric (TG) were used respectively to analyze the compatibility, the melting behavior and thermal stability properties of PLA/PPC blends affected by the different content of PPC. The results showed that with the increase of the PPC content, the glass transition temperature of PLA was reduced, and the glass transition temperature of PPC was increased, which indicated that PLA and PPC had partial compatibility. The cold crystallization temperature of PLA increased with the increase of the PPC content, which showed that PPC hindered the cold crystallization process of PLA. The addition of PPC had little impact on the melting process of PLA, and the melting temperature of PLA was almost kept the same value. Thermogravimetric analysis showed that the thermal stability of PPC was worse than that of PLA, the addition of PPC reduced the thermal stability of PLA.

  4. A low-cost batch process for high-performance melt-textured GdBaCuO pellets

    Science.gov (United States)

    Muralidhar, M.; Tomita, M.; Suzuki, K.; Jirsa, M.; Fukumoto, Y.; Ishihara, A.

    2010-04-01

    High-Tc superconducting magnets promise a variety of industrial, medical, public, and research applications. However, the potential large-scale applications of these materials need excellent and uniform properties and a cheap production method. The batch process developed for the fabrication of GdBa2Cu3Oy pellets in air fulfils all of these requirements. The samples were melt-processed using a cold seeding method with thin film Nd-123 seeds grown on MgO crystals. We used self-made Gd-123 and Gd-211 powders mixed with 0.1 wt% of Pt. Up to 1-1.5 kg of melt-grown Gd-123 bulks could be prepared in one run. XRD analysis confirmed that all of the bulks were c-axis oriented. The superconducting and magnetic performance of the pellets was checked on several small test samples cut out at various standard positions within the bulk. The values were reasonably uniform and the performance was similar to the oxygen-controlled melt-grown Gd-123 samples. The average trapped field at 77 K in the 24 mm diameter batch samples was between 0.8 and 0.9 T, close to the maximum value of 1 T reported so far for Gd-123 single grains processed in air. The present results prove that a high-performance good-quality LREBa2Cu3Oy material can be scaled up from laboratory to industrial production.

  5. Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Wei, E-mail: zw55624@163.com; Chen, Rongyuan; Zhang, Haichen; Qu, Jinping, E-mail: jpqu@scut.edu.cn [National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640 (China)

    2016-03-09

    Poly (lactic acid) (PLA)/Poly (propylene carbonate) (PPC) blends were prepared by vane extruder which is a type of novel polymer processing extruder based on elongation force field. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric (TG) were used respectively to analyze the compatibility, the melting behavior and thermal stability properties of PLA/PPC blends affected by the different content of PPC. The results showed that with the increase of the PPC content, the glass transition temperature of PLA was reduced, and the glass transition temperature of PPC was increased, which indicated that PLA and PPC had partial compatibility. The cold crystallization temperature of PLA increased with the increase of the PPC content, which showed that PPC hindered the cold crystallization process of PLA. The addition of PPC had little impact on the melting process of PLA, and the melting temperature of PLA was almost kept the same value. Thermogravimetric analysis showed that the thermal stability of PPC was worse than that of PLA, the addition of PPC reduced the thermal stability of PLA.

  6. Rheology Guided Rational Selection of Processing Temperature To Prepare Copovidone-Nifedipine Amorphous Solid Dispersions via Hot Melt Extrusion (HME).

    Science.gov (United States)

    Yang, Fengyuan; Su, Yongchao; Zhang, Jingtao; DiNunzio, James; Leone, Anthony; Huang, Chengbin; Brown, Chad D

    2016-10-03

    The production of amorphous solid dispersions via hot melt extrusion (HME) relies on elevated temperature and prolonged residence time, which can result in potential degradation and decomposition of thermally sensitive components. Herein, the rheological properties of a physical mixture of polymer and an active pharmaceutical ingredient (API) were utilized to guide the selection of appropriate HME processing temperature. In the currently studied copovidone-nifedipine system, a critical temperature, which is substantially lower (∼13 °C) than the melting point of crystalline API, was captured during a temperature ramp examination and regarded as the critical point at which the API could molecularly dissolve into the polymer. Based on the identification of this critical point, various solid dispersions were prepared by HME processing below, at, and above the critical temperature (both below and above the melting temperature (T m ) of crystalline API). In addition, the resultant extrudates along with two control solid dispersions prepared by physical mixing and cryogenic milling were assessed by X-ray diffraction, differential scanning calorimetry, hot stage microscopy, rheology, and solid-state NMR. Physicochemical properties of resultant solid dispersions indicated that the identified critical temperature is sufficient for the polymer-API system to reach a molecular-level mixing, manifested by the transparent and smooth appearance of extrudates, the absence of API crystalline diffraction and melting peaks, dramatically decreased rheological properties, and significantly improved polymer-API miscibility. Once the critical temperature has been achieved, further raising the processing temperature only results in limited improvement of API dispersion, reflected by slightly reduced storage modulus and complex viscosity and limited improvement in miscibility.

  7. The effects of polymer carrier, hot melt extrusion process and downstream processing parameters on the moisture sorption properties of amorphous solid dispersions.

    Science.gov (United States)

    Feng, Xin; Vo, Anh; Patil, Hemlata; Tiwari, Roshan V; Alshetaili, Abdullah S; Pimparade, Manjeet B; Repka, Michael A

    2016-05-01

    The aim of this study was to evaluate the effect of polymer carrier, hot melt extrusion and downstream processing parameters on the water uptake properties of amorphous solid dispersions. Three polymers and a model drug were used to prepare amorphous solid dispersions utilizing the hot melt extrusion technology. The sorption-desorption isotherms of solid dispersions and their physical mixtures were measured by the dynamic vapour sorption system, and the effects of polymer hydrophobicity, hygroscopicity, molecular weight and the hot melt extrusion process were investigated. Fourier transform infrared (FTIR) imaging was performed to understand the phase separation driven by the moisture. Solid dispersions with polymeric carriers with lower hydrophilicity, hygroscopicity and higher molecular weight could sorb less moisture under the high relative humidity (RH) conditions. The water uptake ability of polymer-drug solid dispersion systems were decreased compared with the physical mixture after hot melt extrusion, which might be due to the decreased surface area and porosity. The FTIR imaging indicated that the homogeneity of the drug molecularly dispersed within the polymer matrix was changed after exposure to high RH. Understanding the effect of formulation and processing on the moisture sorption properties of solid dispersions is essential for the development of drug products with desired physical and chemical stability. © 2015 Royal Pharmaceutical Society.

  8. Numerical simulation and parametric analysis of selective laser melting process of AlSi10Mg powder

    Science.gov (United States)

    Pei, Wei; Zhengying, Wei; Zhen, Chen; Junfeng, Li; Shuzhe, Zhang; Jun, Du

    2017-08-01

    A three-dimensional numerical model was developed to investigate effects of laser scanning speed, laser power, and hatch spacing on the thermodynamic behaviors of the molten pool during selective laser melting of AlSi10Mg powder. A randomly distributed packed powder bed was achieved using discrete element method (DEM). The powder bed can be treated as a porous media with interconnected voids in the simulation. A good agreement between numerical results and experimental results establish the validity of adopted method. The numerical results show that the Marangoni flow within the molten pool was significantly affected by the processing parameters. An intense Marangoni flow leads to a perturbation within the molten pool. In addition, a relatively high scanning speed tends to cause melt instability. The perturbation or the instability within the molten pool results in the formation of pores during SLM, which have a direct influence on the densification level.

  9. The peculiarities of water crystallization and ice melting processes in the roots of one-year plants (Plantago major L.).

    Science.gov (United States)

    Bakradze, N; Kiziria, E; Sokhadze, V; Gogichaishvili, S

    2008-01-01

    Results are presented of a water phase transition study in plantain (Plantago major L.) roots, which were used as a model system to research the peculiarities of water crystallization and ice melting processes in complex heterogeneous biological systems. It was confirmed that water in such systems is crystallized in two clearly distinguished temperature ranges: -10 to -25 degree capital ES, Cyrillic and -25 to -45 degree capital ES, Cyrillic. These water fractions are conditionally attributed to extracellular (-10 to -25 degree capital ES, Cyrillic) and intracellular (-25 to -45 degree capital ES, Cyrillic) solutions. A possible explanation is given for such significant supercooling of the intracellular solution. The values of osmotic pressures of extra- and intracellular solutions were determined according to ice melting curves. It is noted that the intracellular solution, which crystallized at lower temperatures, had a lower osmotic pressure.

  10. Tensile properties of LDPE/electrical cable waste blends prepared by melt extrusion process

    OpenAIRE

    Franco-Urquiza, Edgar; Camacho, N.; Maspoch Rulduà, Mª Lluïsa

    2017-01-01

    In this study low density poly-ethylene (LDPE)/electrical cable waste blends were prepared using asingle-screw extruder at pilot plant level. The cable waste was mainly composed of LDPE, synthetic rubbers, flexible poly-vinyl chloride (PVC) and traces of conductive metal. Recycled LDPE was recovered by using the gravimetric separation approach. Heterogeneous extruded filaments were obtained because of the presence of not-melted waste particles that caused the interruption of the extrusion pro...

  11. Effect of process parameters on formability of laser melting deposited 12CrNi2 alloy steel

    Science.gov (United States)

    Peng, Qian; Dong, Shiyun; Kang, Xueliang; Yan, Shixing; Men, Ping

    2018-03-01

    As a new rapid prototyping technology, the laser melting deposition technology not only has the advantages of fast forming, high efficiency, but also free control in the design and production chain. Therefore, it has drawn extensive attention from community.With the continuous improvement of steel performance requirements, high performance low-carbon alloy steel is gradually integrated into high-tech fields such as aerospace, high-speed train and armored equipment.However, it is necessary to further explore and optimize the difficult process of laser melting deposited alloy steel parts to achieve the performance and shape control.This article took the orthogonal experiment on alloy steel powder by laser melting deposition ,and revealed the influence rule of the laser power, scanning speed, powder gas flow on the quality of the sample than the dilution rate, surface morphology and microstructure analysis were carried out.Finally, under the optimum technological parameters, the Excellent surface quality of the alloy steel forming part with high density, no pore and cracks was obtained.

  12. Characterization of high-purity niobium structures fabricated using the electron beam melting process

    Science.gov (United States)

    Terrazas Najera, Cesar Adrian

    Additive Manufacturing (AM) refers to the varied set of technologies utilized for the fabrication of complex 3D components from digital data in a layer-by-layer fashion. The use of these technologies promises to revolutionize the manufacturing industry. The electron beam melting (EBM) process has been utilized for the fabrication of fully dense near-net-shape components from various metallic materials. This process, catalogued as a powder bed fusion technology, consists of the deposition of thin layers (50 - 120microm) of metallic powder particles which are fused by the use of a high energy electron beam and has been commercialized by Swedish company Arcam AB. Superconducting radio frequency (SRF) cavities are key components that are used in linear accelerators and other light sources for studies of elemental physics. Currently, cavity fabrication is done by employing different forming processes including deep-drawing and spinning. In both of the latter techniques, a feedstock high-purity niobium sheet with a thickness ranging from 3-4 mm is mechanically deformed and shaped into the desired geometry. In this manner, half cavities are formed that are later joined by electron beam welding (EBW). The welding step causes variability in the shape of the cavity and can also introduce impurities at the surface of the weld interface. The processing route and the purity of niobium are also of utmost importance since the presence of impurities such as inclusions or defects can be detrimental for the SRF properties of cavities. The focus of this research was the use of the EBM process in the manufacture of high purity niobium parts with potential SRF applications. Reactor grade niobium was plasma atomized and used as the precursor material for fabrication using EBM. An Arcam A2 system was utilized for the fabrication. The system had all internal components of the fabrication chamber replaced and was cleaned to prevent contamination of niobium powder. A mini-vat, developed at

  13. Interaction mechanism between niobium-silicide-based alloy melt and Y2O3 refractory crucible in vacuum induction melting process

    Directory of Open Access Journals (Sweden)

    Gao Ming

    2011-05-01

    Full Text Available The Y2O3 crucibles were introduced in the study as an alternative to the traditional ceramic ones in vacuum induction melting of multi-component Nb-16Si-22Ti-2Al-2Hf-17Cr (at.% alloys, to reveal the possible interactions between the alloy melt and the refractory crucible. Multiple melting time lengths and two cooling schemes were designed and used for the experiments. The chemical composition and microstructure of the tested alloy and the melt-crucible interaction were investigated and evaluated. In the experiments, Y2O3 crucible displays good physical-chemical compatibility. The results indicate that the increment of O element in the as-cast ingot is 0.03at.%-0.04at.% (72-97 ppm and the increment of Y element is very insignificant. The key features of the alloy melt interacting with Y2O3 ceramics are analyzed and concluded in the paper. As a result of the dissolution reaction xY2O3 (in molten alloy + (1-xHfO2 (impurity →Hf1-xY2xO2-x, a continuous double-layer solid film consisted of HfO2 solid solution (~2 μm and pure HfO2 (~5 μm is formed on the surface of the test ingot after cooled down in the crucible. The experimental results show that the Y2O3 crucible is applicable to the vacuum induction melting of Nb-Si based alloys.

  14. Melt-processable hydrophobic acrylonitrile-based copolymer systems with adjustable elastic properties designed for biomedical applications.

    Science.gov (United States)

    Cui, J; Trescher, K; Kratz, K; Jung, F; Hiebl, B; Lendlein, A

    2010-01-01

    Acrylonitrile-based polymer systems (PAN) are comprehensively explored as versatile biomaterials having various potential biomedical applications, such as membranes for extra corporal devices or matrixes for guided skin reconstruction. The surface properties (e.g. hydrophilicity or charges) of such materials can be tailored over a wide range by variation of molecular parameters such as different co-monomers or their sequence structure. Some of these materials show interesting biofunctionalities such as capability for selective cell cultivation. So far, the majority of AN-based copolymers, which were investigated in physiological environments, were processed from the solution (e.g. membranes), as these materials are thermo-sensitive and might degrade when heated. In this work we aimed at the synthesis of hydrophobic, melt-processable AN-based copolymers with adjustable elastic properties for preparation of model scaffolds with controlled pore geometry and size. For this purpose a series of copolymers from acrylonitrile and n-butyl acrylate (nBA) was synthesized via free radical copolymerisation technique. The content of nBA in the copolymer varied from 45 wt% to 70 wt%, which was confirmed by 1H-NMR spectroscopy. The glass transition temperatures (Tg) of the P(AN-co-nBA) copolymers determined by differential scanning calorimetry (DSC) decreased from 58 degrees C to 20 degrees C with increasing nBA-content, which was in excellent agreement with the prediction of the Gordon-Taylor equation based on the Tgs of the homopolymers. The Young's modulus obtained in tensile tests was found to decrease significantly with rising nBA-content from 1062 MPa to 1.2 MPa. All copolymers could be successfully processed from the melt with processing temperatures ranging from 50 degrees C to 170 degrees C, whereby thermally induced decomposition was only observed at temperatures higher than 320 degrees C in thermal gravimetric analysis (TGA). Finally, the melt processed P

  15. ANALYSIS OF THERMAL CONDUCTION AT MELTING OF METAL BRICKS IN LIQUID BATH. MESSAGE 2. MODELING AND CALCULATION OF PROCESS OF THE ALLOYED STEEL BRICKS MELTING IN MODEM MELTING AGGREGATES

    Directory of Open Access Journals (Sweden)

    V. I. Timoshpolskij

    2006-01-01

    Full Text Available The methods of calculation of duration of the metallic bricks heating and melting in liquid bath, taking into account variability of thermal-physical characteristics of metal due to temperature, is developed.

  16. A combined experimental and theoretical approach to establish the relationship between shear force and clay platelet delamination in melt-processed polypropylene nanocomposites

    CSIR Research Space (South Africa)

    Bandyopadhyay, J

    2014-04-01

    Full Text Available In this article, a combined experimental and theoretical approach has been proposed to establish a relationship between the required shear force and the degree of delamination of clay tactoids during the melt-processing of polymer nanocomposites...

  17. On the Selective Laser Melting (SLM of the AlSi10Mg Alloy: Process, Microstructure, and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Francesco Trevisan

    2017-01-01

    Full Text Available The aim of this review is to analyze and to summarize the state of the art of the processing of aluminum alloys, and in particular of the AlSi10Mg alloy, obtained by means of the Additive Manufacturing (AM technique known as Selective Laser Melting (SLM. This process is gaining interest worldwide, thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical properties related to a very fine microstructure. However, SLM is very complex, from a physical point of view, due to the interaction between a concentrated laser source and metallic powders, and to the extremely rapid melting and the subsequent fast solidification. The effects of the main process variables on the properties of the final parts are analyzed in this review: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power and speed, layer thickness, and scanning strategy. Furthermore, a detailed overview on the microstructure of the AlSi10Mg material, with the related tensile and fatigue properties of the final SLM parts, in some cases after different heat treatments, is presented.

  18. On the Selective Laser Melting (SLM) of the AlSi10Mg Alloy: Process, Microstructure, and Mechanical Properties.

    Science.gov (United States)

    Trevisan, Francesco; Calignano, Flaviana; Lorusso, Massimo; Pakkanen, Jukka; Aversa, Alberta; Ambrosio, Elisa Paola; Lombardi, Mariangela; Fino, Paolo; Manfredi, Diego

    2017-01-18

    The aim of this review is to analyze and to summarize the state of the art of the processing of aluminum alloys, and in particular of the AlSi10Mg alloy, obtained by means of the Additive Manufacturing (AM) technique known as Selective Laser Melting (SLM). This process is gaining interest worldwide, thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical properties related to a very fine microstructure. However, SLM is very complex, from a physical point of view, due to the interaction between a concentrated laser source and metallic powders, and to the extremely rapid melting and the subsequent fast solidification. The effects of the main process variables on the properties of the final parts are analyzed in this review: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power and speed, layer thickness, and scanning strategy. Furthermore, a detailed overview on the microstructure of the AlSi10Mg material, with the related tensile and fatigue properties of the final SLM parts, in some cases after different heat treatments, is presented.

  19. Usage of Thermodynamic Activity for Optimization of Power Expenses in Respect of Casting Process in Arc Steel-Melting Furnace

    Directory of Open Access Journals (Sweden)

    A. N. Chichko

    2006-01-01

    Full Text Available The equilibrium between carbon and oxygen has been investigated during oxidizing refining in an arc steel-melting furnace. It is shown that there is a possibility to apply an equilibrium thermodynamic. It has been established that during oxidizing refining FeO concentration in slag practically does not depend on C concentration in metal. It is demonstrated that in a number of cases metal carbon oxidation is characterized by the presence of a transit period that may be attributed to incomplete slag-formation process.

  20. Process design and control of a twin screw hot melt extrusion for continuous pharmaceutical tamper-resistant tablet production.

    Science.gov (United States)

    Baronsky-Probst, J; Möltgen, C-V; Kessler, W; Kessler, R W

    2016-05-25

    Hot melt extrusion (HME) is a well-known process within the plastic and food industries that has been utilized for the past several decades and is increasingly accepted by the pharmaceutical industry for continuous manufacturing. For tamper-resistant formulations of e.g. opioids, HME is the most efficient production technique. The focus of this study is thus to evaluate the manufacturability of the HME process for tamper-resistant formulations. Parameters such as the specific mechanical energy (SME), as well as the melt pressure and its standard deviation, are important and will be discussed in this study. In the first step, the existing process data are analyzed by means of multivariate data analysis. Key critical process parameters such as feed rate, screw speed, and the concentration of the API in the polymers are identified, and critical quality parameters of the tablet are defined. In the second step, a relationship between the critical material, product and process quality attributes are established by means of Design of Experiments (DoEs). The resulting SME and the temperature at the die are essential data points needed to indirectly qualify the degradation of the API, which should be minimal. NIR-spectroscopy is used to monitor the material during the extrusion process. In contrast to most applications in which the probe is directly integrated into the die, the optical sensor is integrated into the cooling line of the strands. This saves costs in the probe design and maintenance and increases the robustness of the chemometric models. Finally, a process measurement system is installed to monitor and control all of the critical attributes in real-time by means of first principles, DoE models, soft sensor models, and spectroscopic information. Overall, the process is very robust as long as the screw speed is kept low. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Processing and characterization of Al–Cu–Li alloy AA2195 undergoing scale up production through the vacuum induction melting technique

    International Nuclear Information System (INIS)

    Nayan, Niraj; Murty, S.V.S. Narayana; Jha, Abhay K.; Pant, Bhanu; Sharma, S.C.; George, Koshy M.; Sastry, G.V.S.

    2013-01-01

    The inherent properties of lithium, such as high reactivity and toxicity, relatively low density, low melting point, along with its high cost requires a special technological approach to cast Al–Cu–Li alloy AA2195 as compared to the conventional Direct Chill (DC) casting of aluminum alloys. This paper describes the processing requirements for melting and casting of 200 kg of Al–Cu–Li alloy in a Vacuum Induction Melting (VIM) furnace under dynamic inert atmosphere. The as-cast billets have been homogenized to remove microsegregation as well as to avoid incipient melting, and subsequently subjected for secondary metal processing operations viz., forging and rolling. The product in the form of 4 mm thick sheets was subjected to various heat treatments in T8 (Solution Treatment+WQ+CW+Aging) condition. Mechanical properties were evaluated at room temperature and were correlated with microstructures of the sheets processed under different conditions using transmission electron microscopy (TEM)

  2. Analysis of grain growth process in melt spun Fe-B alloys under the initial saturated grain boundary segregation condition

    International Nuclear Information System (INIS)

    Chen, Z.; Liu, F.; Yang, X.Q.; Fan, Y.; Shen, C.J.

    2012-01-01

    Highlights: → We compared pure kinetic, pure thermodynamic and extended thermo-kinetic models. → An initial saturated GB segregation condition of nanoscale Fe-B alloys was determined. → The controlled-mechanism was proposed using two characteristic times (t 1 and t 2 ). - Abstract: A grain growth process in the melt spun low-solid-solubility Fe-B alloys was analyzed under the initial saturated grain boundary (GB) segregation condition. Applying melt spinning technique, single-phase supersaturated nanograins were prepared. Grain growth behavior of the single-phase supersaturated nanograins was investigated by performing isothermal annealing at 700 deg. C. Combined with the effect of GB segregation on the initial GB excess amount, the thermo-kinetic model [Chen et al., Acta Mater. 57 (2009) 1466] was extended to describe the initial GB segregation condition of nanoscale Fe-B alloys. In comparison of pure kinetic model, pure thermodynamic model and the extended thermo-kinetic model, an initial saturated GB segregation condition was determined. The controlled-mechanism of grain growth under initial saturated GB segregation condition was proposed using two characteristic annealing times (t 1 and t 2 ), which included a mainly kinetic-controlled process (t ≤ t 1 ), a transition from kinetic-mechanism to thermodynamic-mechanism (t 1 2 ) and pure thermodynamic-controlled process (t ≥ t 2 ).

  3. [Energy dispersive spectrum analysis of surface compositions of selective laser melting cobalt-chromium alloy fabricated by different processing parameters].

    Science.gov (United States)

    Qian, Liang; Zeng, Li; Wei, Bin; Gong, Yao

    2015-06-01

    To fabricate selective laser melting cobalt-chromium alloy samples by different processing parameters, and to analyze the changes of energy dispersive spectrum(EDS) on their surface. Nine groups were set up by orthogonal experimental design according to different laser powers,scanning speeds and powder feeding rates(laser power:2500-3000 W, scanning speed: 5-15 mm/s, powder feeding rate: 3-6 r/min). Three cylinder specimens(10 mm in diameter and 3 mm in thickness) were fabricated in each group through Rofin DL 035Q laser cladding system using cobalt-chromium alloy powders which were developed independently by our group.Their surface compositions were then measured by EDS analysis. Results of EDS analysis of the 9 groups fabricated by different processing parameters(Co:62.98%-67.13%,Cr:25.56%-28.50%,Si:0.49%-1.23%) were obtained. They were similar to the compositions of cobalt-chromium alloy used in dental practice. According to EDS results, the surface compositions of the selective laser melting cobalt-chromium alloy samples are stable and controllable, which help us gain a preliminary sight into the range of SLM processing parameters. Supported by "973" Program (2012CB910401) and Research Fund of Science and Technology Committee of Shanghai Municipality (12441903001 and 13140902701).

  4. FeAl-TiC and FeAl-WC composites - melt infiltration processing, microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, R.; Schneibel, J.H.

    1997-04-01

    TiC-based and WC-based cermets were processed with iron aluminide, an intermetallic, as a binder by pressureless melt infiltration to near full density (> 97 % theoretical density). Phase equilibria calculations in the quaternary Fe-Al-Ti-C and Fe-Al-W-C systems at 145{degrees}C were performed to determine the solubility of the carbide phases in liquid iron aluminide. This was done by using Thermocalc{trademark} and the results show that molten Fe-40 at.% Al in equilibrium with Ti{sub 0.512}C{sub 0.488} and graphite, dissolves 4.9 at% carbon and 64 atomic ppm titanium. In the Fe-Al-W-C system, liquid Fe-40 at.% Al in equilibrium with graphite dissolves about 5 at.% carbon and 1 at.% tungsten. Due to the low values for the solubility of the carbide phases in liquid iron aluminide, liquid phase sintering of mixed powders does not yield a dense, homogeneous microstructure for carbide volume fractions greater than 0.70. Melt infiltration of molten FeAl into TiC and WC preforms serves as a successful approach to process cermets with carbide contents ranging from 70 to 90 vol. %, to greater than 97% of theoretical density. Also, the microstructures of cermets prepared by melt infiltration were very homogeneous. Typical properties such as hardness, bend strength and fracture toughness are reported. SEM observations of fracture surfaces suggest the improved fracture toughness to result from the ductility of the intermetallic phase. Preliminary experiments for the evaluation of the oxidation resistance of iron aluminide bonded cermets indicate that they are more resistant than WC-Co cermets.

  5. Study of Processing and Mechanical Behavior of Pp/clay Nanocomposites Prepared by Melt Blending

    Science.gov (United States)

    Shirazi, Sareh Mosleh; Janghorban, Kamal

    In this research, the melt blending technique was used to prepare various polypropylene (PP) based nanocomposites containing 1,3,5,7 wt% montmorillonite (MMT). A commercial organoclay (denoted K-10) served as the filler for PP matrix and the polypropylene grafted maleic anhydride (PP-g-MA) was used as compatibalizer. The morphology of the nanocomposites was studied by X-ray diffraction (XRD), results of which showed that the nanocomposites are best described as intercalated-exfoliated systems. PP/MMT nanocomposites showed good thermal stability in the TGA analysis. Introducion of 3% MMT in the nanocomposites increased the onset temperature of the degradation by 27.5 °C compared to that of pure PP. Test results showed that PP/clay nanocomposites had an enhanced tensile strength, hardness and decreased wear rates.

  6. Influence of Pressure Field in Melts on the Primary Nucleation in Solidification Processing

    Science.gov (United States)

    Rakita, Milan; Han, Qingyou

    2017-10-01

    It is well known that external fields applied to melts can cause nucleation at lower supercoolings, fragmentation of growing dendrites, and forced convection around the solidification front. All these effects contribute to a finer microstructure of solidified material. In this article, we analyze how the pressure field created with ultrasonic vibrations influences structure refinement in terms of supercooling. It is shown that only high cavitation pressures of the order of 104 atmospheres are capable of nucleating crystals at minimal supercoolings. We demonstrate the possibility of sononucleation even in superheated liquid. Simulation and experiments with water samples show that very high cavitation pressures occur in a relatively narrow zone where the drive acoustic field has an appropriate combination of pressure amplitude and frequency. In order to accurately predict the microstructure formed by ultrasonically assisted solidification of metals, this article calls for the development of equations of state that would describe the pressure-dependent behavior of molten metals.

  7. X-ray Tomography Characterisation of Lattice Structures Processed by Selective Electron Beam Melting

    Directory of Open Access Journals (Sweden)

    Everth Hernández-Nava

    2017-08-01

    Full Text Available Metallic lattice structures intentionally contain open porosity; however, they can also contain unwanted closed porosity within the structural members. The entrained porosity and defects within three different geometries of Ti-6Al-4V lattices, fabricated by Selective Electron Beam Melting (SEBM, is assessed from X-ray computed tomography (CT scans. The results suggest that horizontal struts that are built upon loose powder show particularly high (~20 × 10−3 vol % levels of pores, as do nodes at which many (in our case 24 struts meet. On the other hand, for struts more closely aligned (0° to 54° to the build direction, the fraction of porosity appears to be much lower (~0.17 × 10−3% arising mainly from pores contained within the original atomised powder particles.

  8. Microstructure of Semi-Solid 6063 Alloy Fabricated by Radial Forging Combined with Unidirectional Compression Recrystallization and Partial Melting Process

    Directory of Open Access Journals (Sweden)

    Wang Yongfei

    2017-01-01

    Full Text Available Radial forging combined with unidirectional compression (RFCUM is introduced in recrystallization and partial melting (RAP to fabricate semi-solid 6063 aluminum alloy, which can be defined as a process of RFCUM-RAP. In this study, the microstructures of semi-solid 6063 alloy prepared by semi-solid isothermal treatment (SSIT and RFCUM-RAP processes are investigated. The results show that, the solid grains of semi-solid alloy prepared by SSIT are large and irregular. However, solid grains of semi-solid billet prepared by RFCUC-RAP are fine and spherical. Additionally, during RFCUC-RAP process, with the increase of isothermal holding time, the shape of solid grain is more and more spherical, but the size of solid grain is gradually increased. To obtain ideal semi-solid microstructure, the optimal isothermal holding temperature and time are 630 °C and 5~10 min, respectively.

  9. Crystallization of nuclear glass under a thermal gradient: application to the self-crucible produced in the skull melting process

    International Nuclear Information System (INIS)

    Delattre, O.

    2013-01-01

    In the context of the vitrification of high level nuclear waste, a new industrial process has been launched in 2010 at the La Hague factory: The skull melting process. This setup applies thermal gradients to the melt, which leads to the formation of a solid layer of glass: the 'self-crucible'. The question would be to know whether these thermal gradients have an impact or not on the crystallization behaviour of the considered glasses in the self crucible. In order to answer that question, the crystallization of two glass compositions of nuclear interest has been investigated with an image analysis based method in isothermal and thermal gradient heat treatments conditions. The isothermal experiments allow for the quantification (growth speed, nucleation, crystallized fraction) of the crystallization of apatites (660 C-900 C) and powellites (630 C-900 C). The comparison of the results obtained through these two types of experimentations allows us to conclude that there is no impact of the thermal gradient on the crystallization of the studied glass compositions. In order to complete the image analysis study (based on surfaces), in and ex situ microtomography experiments have been performed at ESRF (Grenoble) on the ID19 beamline. This study allowed us to follow the crystallization of apatites in a simplified glass and to confirm the reliability of the image analysis method based on the analysis of surfaces. (author) [fr

  10. Fabrication and heat treatment of high strength Al-Cu-Mg alloy processed using selective laser melting

    Science.gov (United States)

    Zhang, Hu; Zhu, Haihong; Nie, Xiaojia; Qi, Ting; Hu, Zhiheng; Zeng, Xiaoyan

    2016-04-01

    The proposed paper illustrates the fabrication and heat treatment of high strength Al-Cu-Mg alloy produced by selective laser melting (SLM) process. Al-Cu-Mg alloy is one of the heat treatable aluminum alloys regarded as difficult to fusion weld. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, 3D Al-Cu-Mg parts with relative high density of 99.8% are produced by SLM from gas atomized powders. Room temperature tensile tests reveal a remarkable mechanical behavior: the samples show yield and tensile strengths of about 276 MPa and 402 MPa, respectively, along with fracture strain of 6%. The effect of solution treatment on microstructure and related tensile properties is examined and the results demonstrate that the mechanical behavior of the SLMed Al-Cu-Mg samples can be greatly enhanced through proper heat treatment. After T4 solution treatment at 540°C, under the effect of precipitation strengthening, the tensile strength and the yield strength increase to 532 MPa and 338 MPa, respectively, and the elongation increases to 13%.

  11. Influence of electron beam Irradiation on PP/Piassava fiber composite prepared by melt extrusion process

    International Nuclear Information System (INIS)

    Gomes, Michelle G.; Ferreira, Maiara S.; Oliveira, Rene R.; Silva, Valquiria A.; Teixeira, Jaciele G.; Moura, Esperidiana A.B.

    2013-01-01

    In the latest years, the interest for the use of natural fibers in materials composites polymeric has increased significantly due to their environmental and technological advantages. Piassava fibers (Attalea funifera) have been used as reinforcement in the matrix of thermoplastic and thermoset polymers. In the present work (20%, in mass), piassava fibers with particle sizes equal or smaller than 250 μm were incorporated in the polypropylene matrix (PP) no irradiated and polypropylene matrix containing 10 % and 30 % of polypropylene treated by electron-beam radiation at 40 kGy (PP/PPi/Piassava). The composites PP/Piassava and PP/PPi/Piassava were prepared by using a twin screw extruder, followed by injection molding. The composite material samples obtained were treated by electron-beam radiation at 40 kGy, using a 1.5 MeV electron beam accelerator, at room temperature, in presence of air. After irradiation treatment, the irradiated and non-irradiated specimens tests samples were submitted to thermo-mechanical tests, melt flow index (MFI), sol-gel analysis, X-Ray diffraction (XRD) and scanning electron microscopy (SEM). (author)

  12. Alternating-current transport losses of melt-cast processed Bi-2212 bulk superconductor bars

    International Nuclear Information System (INIS)

    Tsukamoto, T; Inada, R; Inagaki, N; Andoh, H; Sugiura, T; Oota, A

    2003-01-01

    Using a melt-casting method, we have fabricated two pieces of Bi-2212 bulk superconductor bar with square and rectangular cross-sections, and we have investigated the alternating-current (ac) transport self-field losses at 77 K. Despite the main contribution of hysteresis loss of the superconductor, there is some difference in the loss behaviour between these two samples. To elucidate the origin, we make numerical calculations on the ac transport self-field losses as a function of current amplitude I 0 below the critical current I c . At a fixed I 0 , the calculated values using the uniform J c distribution and the actual cross-sectional geometry are much higher than the experimental data for the sample with a square cross-section 7.5 x 7.5 mm 2 , while there is good agreement between the calculation and the experiment for the sample with a rectangular cross-section 4.5 x 13.6 mm 2 . The discrepancy appearing in the sample with a square cross-section is ascribed to the actual J c distribution, which is confirmed by critical current measurements when scraping off the sample. The local J c value decreases significantly in going from the surface to the interior of the sample. This suppresses the extension of the flux-penetration region to the interior under ac current transmission and lowers the loss generation compared with the calculated results obtained by the uniform J c distribution

  13. Initial crystallization and growth in melt processing of large-domain YBa2Cu3Ox for magnetic levitation

    International Nuclear Information System (INIS)

    Shi, D.

    1994-10-01

    Crystallization temperature in YBa 2 Cu 3 O x (123) during peritectic reaction has been studied by differential thermal analysis (DTA) and optical microscopy. It has been found that YBa 2 Cu 3 O x experiences partial melting near 1,010 C during heating while crystallization takes place at a much lower temperature range upon cooling indicating a delayed nucleation process. A series of experiments have been conducted to search for the initial crystallization temperature in the Y 2 BaCuO x + liquid phase field. The authors have found that the slow-cool period (1 C/h) for the 123 grain texturing can start at as low as 960 C. This novel processing has resulted in high-quality, large-domain, strongly pinned 123 magnetic levitators

  14. Studies on Al-Cu-Li-Mg-Ag-Zr alloy processed through vacuum induction melting (VIM) technique

    International Nuclear Information System (INIS)

    Nayan, Niraj; Govind; Nair, K. Suseelan; Mittal, M.C.; Sudhakaran, K.N.

    2007-01-01

    A new technique of lithium addition has been adapted for the processing of Al-Cu-Li-Ag-Mg-Zr alloy, which gives more than 90% recovery of lithium throughout the billet. Processing studies on this alloy include casting, three step homogenization, to avoid incipient melting, and mechanical working particularly forging and rolling. The products in the form of sheets were subjected to various T6 (solution treatment + water quenching + aging) tempers. Mechanical properties were evaluated at room temperature and correlated with microstructure. Characterizations using optical microscope and post-fracture analysis have been carried out using Scanning electron microscope (SEM). Experimental investigation shows highest mechanical properties for the Al-1.3%Li alloy in T6 (500 deg. C/1 h + WQ + 190 deg. C/24 h) condition

  15. The 2011 eruption of Nabro volcano, Eritrea: perspectives on magmatic processes from melt inclusions

    Science.gov (United States)

    Donovan, Amy; Blundy, Jon; Oppenheimer, Clive; Buisman, Iris

    2018-01-01

    The 2011 eruption of Nabro volcano, Eritrea, produced one of the largest volcanic sulphur inputs to the atmosphere since the 1991 eruption of Mt. Pinatubo, yet has received comparatively little scientific attention. Nabro forms part of an off-axis alignment, broadly perpendicular to the Afar Rift, and has a history of large-magnitude explosive silicic eruptions, as well as smaller more mafic ones. Here, we present and analyse extensive petrological data obtained from samples of trachybasaltic tephra erupted during the 2011 eruption to assess the pre-eruptive magma storage system and explain the large sulphur emission. We show that the eruption involved two texturally distinct batches of magma, one of which was more primitive and richer in sulphur than the other, which was higher in water (up to 2.5 wt%). Modelling of the degassing and crystallisation histories demonstrates that the more primitive magma rose rapidly from depth and experienced degassing crystallisation, while the other experienced isobaric cooling in the crust at around 5 km depth. Interaction between the two batches occurred shortly before the eruption. The eruption itself was likely triggered by recharge-induced destabilisation of vertically extensive mush zone under the volcano. This could potentially account for the large volume of sulphur released. Some of the melt inclusions are volatile undersaturated, and suggest that the original water content of the magma was around 1.3 wt%, which is relatively high for an intraplate setting, but consistent with seismic studies of the Afar plume. This eruption was smaller than some geological eruptions at Nabro, but provides important insights into the plumbing systems and dynamics of off-axis volcanoes in Afar.

  16. Melt Processing and Characterization of Al-SiC Nanocomposite, Al, and Mg Foam Materials

    Directory of Open Access Journals (Sweden)

    Ahmed M. Nabawy

    2016-05-01

    Full Text Available In the present work, metallic foams of Al, Mg and an Al-SiC nanocomposite (MMNC have been fabricated using a new manufacturing technique by employing melt infiltration assisted with an electromagnetic force. The aim of this investigation was to study and to develop a reliable manufacturing technique consisting of different types of metallic foams. In this technique, an electromagnetic force was used to assist the infiltration of Al-SiC slurry and of pure liquid metal into a leachable pattern of NaCl, thus providing perfect cellular structures with micro-sized porosities. A high frequency induction coil unit equipped with a vacuum chamber and a hydraulic press was used to manufacture the foam materials. Microstructures of the produced foam materials were explored by using Field Emission Scanning Electron Microscopy (FESEM. The mechanical behavior of the manufactured foams was investigated by applying compression testing. The results indicate a high applicability of the new technique in producing metallic foams of pure metals and of a metal matrix nanocomposite . The produced foam materials displayed isotropic cellular structures with excellent compressive behaviors. Microstructure measurements indicate that the average pore size and strut thickness that can be achieved are in the ranges of 100–500 μm and 50–100 μm, respectively. The produced foam of the Al-SiC nanocomposite material provided the highest strength of 50 MPa prior to the densification stage, which equates to 25 times, and 10 times higher than the strength levels that were obtained by Al, and Mg foams, respectively.

  17. GLASS MELTING PHENOMENA, THEIR ORDERING AND MELTING SPACE UTILISATION

    Directory of Open Access Journals (Sweden)

    Němec L.

    2013-12-01

    Full Text Available Four aspects of effective glass melting have been defined – namely the fast kinetics of partial melting phenomena, a consideration of the melting phenomena ordering, high utilisation of the melting space, and effective utilisation of the supplied energy. The relations were defined for the specific melting performance and specific energy consumption of the glass melting process which involve the four mentioned aspects of the process and indicate the potentials of effective melting. The quantity “space utilisation” has been treated in more detail as an aspect not considered in practice till this time. The space utilisation was quantitatively defined and its values have been determined for the industrial melting facility by mathematical modelling. The definitions of the specific melting performance and specific energy consumption have been used for assessment of the potential impact of a controlled melt flow and high space utilisation on the melting process efficiency on the industrial scale. The results have shown that even the partial control of the melt flow, leading to the partial increase of the space utilisation, may considerably increase the melting performance, whereas a decrease of the specific energy consumption was determined to be between 10 - 15 %.

  18. Melt processing and property testing of a model system of plastics contained in waste from electrical and electronic equipment.

    Science.gov (United States)

    Triantou, Marianna I; Tarantili, Petroula A; Andreopoulos, Andreas G

    2015-05-01

    In the present research, blending of polymers used in electrical and electronic equipment, i.e. acrylonitrile-butadiene-styrene terpolymer, polycarbonate and polypropylene, was performed in a twin-screw extruder, in order to explore the effect process parameters on the mixture properties, in an attempt to determine some characteristics of a fast and economical procedure for waste management. The addition of polycarbonate in acrylonitrile-butadiene-styrene terpolymer seemed to increase its thermal stability. Also, the addition of polypropylene in acrylonitrile-butadiene-styrene terpolymer facilitates its melt processing, whereas the addition of acrylonitrile-butadiene-styrene terpolymer in polypropylene improves its mechanical performance. Moreover, the upgrading of the above blends by incorporating 2 phr organically modified montmorillonite was investigated. The prepared nanocomposites exhibit greater tensile strength, elastic modulus and storage modulus, as well as higher melt viscosity, compared with the unreinforced blends. The incorporation of montmorillonite nanoplatelets in polycarbonate-rich acrylonitrile-butadiene-styrene terpolymer/polycarbonate blends turns the thermal degradation mechanism into a two-stage process. Alternatively to mechanical recycling, the energy recovery from the combustion of acrylonitrile-butadiene-styrene terpolymer/polycarbonate and acrylonitrile-butadiene-styrene terpolymer/polypropylene blends was recorded by measuring the gross calorific value. Comparing the investigated polymers, polypropylene presents the higher gross calorific value, followed by acrylonitrile-butadiene-styrene terpolymer and then polycarbonate. The above study allows a rough comparative evaluation of various methodologies for treating plastics from waste from electrical and electronic equipment. © The Author(s) 2015.

  19. Investigation of the interactions of enteric and hydrophilic polymers to enhance dissolution of griseofulvin following hot melt extrusion processing.

    Science.gov (United States)

    Bennett, Ryan C; Keen, Justin M; Bi, Yunxia Vivian; Porter, Stuart; Dürig, Thomas; McGinity, James W

    2015-07-01

    This study focuses on the application of hot melt extrusion (HME) to produce solid dispersions containing griseofulvin (GF) and investigates the in-vitro dissolution performance of HME powders and resulting tablet compositions containing HME-processed dispersions. Binary, ternary and quaternary dispersions containing GF, enteric polymer (Eudragit L100-55 or AQOAT-LF) and/or vinyl pyrrolidone-based polymer (Plasdone K-12 povidone or S-630 copovidone) were processed by HME. Two plasticizers, triethyl citrate (TEC) and acetyl tributyl citrate (ATBC), were incorporated to aid in melt processing and to modify release of GF in neutral media following a pH-change in dissolution. Products were characterized for GF recovery, degrees of compositional amorphous character, intermolecular interactions and non-sink dissolution performance. Binary dispersions exhibited lower maximum observed concentration values and magnitudes of supersaturated GF in neutral media dissolution in comparison with the ternary dispersions. The quaternary HME products, 1 : 2 : 1 : 0.6 GF : L100-55 : S-630 : ATBC and GF : AQOAT-LF : K-12 : ATBC, were determined as the most optimal concentration-enhancing compositions due to increased hydrogen bonding of enteric functional groups with carbonyl/acetate groups of vinyl pyrrolidone-based polymers, reduced compositional crystallinity and presence of incorporated hydrophobic plasticizer. HME products containing combinations of concentration-enhancing polymers can supersaturate and sustain GF dissolution to greater magnitudes in neutral media following the pH-transition and be compressed into immediate-release tablets exhibiting similar dissolution profiles. © 2015 Royal Pharmaceutical Society.

  20. Determination of the melting threshold of TiO{sub 2} thin films processed by excimer laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Van Overschelde, O. [Chimie des Interactions Plasma-Surface, Universite de Mons, 23, Place du Parc, 7000 Mons (Belgium); Delsate, T. [Service de Physique Theorique et Mathematique, Universite de Mons, 6 Avenue du champ de Mars, 7000 Mons (Belgium); Snyders, R. [Chimie des Interactions Plasma-Surface, Universite de Mons, 23, Place du Parc, 7000 Mons (Belgium); Materia Nova Research Center, 1 Avenue Copernic, 7000 Mons (Belgium)

    2012-06-15

    Processing surfaces by laser needs an understanding of the mechanisms generated by irradiation. In this work, to gain understanding of the mechanisms occurring during irradiation of TiO{sub 2} thin films by means of KrF excimer laser, we have performed infrared time resolved reflectivity measurements. This experimental investigation revealed modifications of the heating/cooling cycle as a function of the fluence (F). These modifications start appearing for a fluence value of about {approx}0.25 J/cm{sup 2} which is associated with the melting threshold of the film. Additionally, we have solved numerically the heat equation of the system with specific boundary conditions. From these calculations, we have established the thermal history of the film during the 25 ns irradiation pulse. The data reveal that a part of the medium liquefies around a fluence of 0.23 J/cm{sup 2} in good agreement with the experimental data.

  1. Experimental Study of the Melting and Reduction Behaviour of Ore Used in the HIsarna Process

    NARCIS (Netherlands)

    Qu, Y.

    2013-01-01

    The HIsarna is a coal-based smelting reduction process for ironmaking to drastically reduce CO2 emission and is one of the most promising alternative ironmaking processes under development in the world. The furnace consists of two inter-connected reactors: i) a smelting cyclone, ii) a smelting

  2. Investigation of the crystallization process of titanium alloy ingots produced by vacuum arc melting method

    International Nuclear Information System (INIS)

    Tetyukhin, V.V.; Kurapov, V.N.; Trubin, A.N.; Demchenko, M.V.; Lazarev, V.G.; Ponedilko, S.V.; Dubrovina, N.T.; Kurapova, L.A.

    1978-01-01

    The process of crystallization and hardening of the VT3-1 and VT9 titanium alloys ingots during the vacuum-arc remelting (VAR) has been studied. In order to investigate the kinetics of the hole shape changing and the peculiarities of the ingot formation during the VAR, the radiography method has been used. It is established that the VAR of the titanium alloy ingots is basically a continuous process. An intense heating of the liquid bath mirror and the availability of high temperature gradients in the hole are the typical features of the VAR process

  3. Morphology of Near- and Semispherical Melted Chips after the Grinding Processes Using Sol-Gel Abrasives Based on SEM-Imaging and Analysis

    Directory of Open Access Journals (Sweden)

    W. Kapłonek

    2016-01-01

    Full Text Available Selected issues related to SEM-imaging and image analysis of spherical melted chips formed during the grinding process are presented and discussed. The general characteristics of this specific group of machining products are given. Chip formation phenomena, as well as their overall morphology, are presented using selected examples of near- and semispherical melted chips occurring singly or concentrated in clusters on the grinding wheel surface after the machining process. Observation of the spherical melted chips and acquisition of their images were carried out for grinding wheel active surfaces with microcrystalline sintered corundum abrasive grains SG™ after the internal cylindrical grinding process of a 100Cr6 steel and Titanium Grade 2® alloy by use of a scanning electron microscope, JEOL JSM-5500LV. Analysis of the obtained SEM micrographs was carried out by Image-Pro® Plus 5.0 software to determine the selected geometrical parameters describing the morphological features of the assessed chips.

  4. Effects of Processing Parameters on Surface Roughness of Additive Manufactured Ti-6Al-4V via Electron Beam Melting.

    Science.gov (United States)

    Wang, Pan; Sin, Wai Jack; Nai, Mui Ling Sharon; Wei, Jun

    2017-09-22

    As one of the powder bed fusion additive manufacturing technologies, electron beam melting (EBM) is gaining more and more attention due to its near-net-shape production capacity with low residual stress and good mechanical properties. These characteristics also allow EBM built parts to be used as produced without post-processing. However, the as-built rough surface introduces a detrimental influence on the mechanical properties of metallic alloys. Thereafter, understanding the effects of processing parameters on the part's surface roughness, in turn, becomes critical. This paper has focused on varying the processing parameters of two types of contouring scanning strategies namely, multispot and non-multispot, in EBM. The results suggest that the beam current and speed function are the most significant processing parameters for non-multispot contouring scanning strategy. While for multispot contouring scanning strategy, the number of spots, spot time, and spot overlap have greater effects than focus offset and beam current. The improved surface roughness has been obtained in both contouring scanning strategies. Furthermore, non-multispot contouring scanning strategy gives a lower surface roughness value and poorer geometrical accuracy than the multispot counterpart under the optimized conditions. These findings could be used as a guideline for selecting the contouring type used for specific industrial parts that are built using EBM.

  5. Registration of melting and crystallization process of MCMgLi8Ca5 alloy with use of ATND method

    Directory of Open Access Journals (Sweden)

    J. Pezda

    2009-04-01

    Full Text Available Among lightweight metal alloys, magnesium is the lightest structural material with density of 1.74 g/cm3, having many attractive physical and mechanical properties combined with processing advantages. Therefore, it represents very attractive material for large amountof applications starting from automotive industry as the main user, up to other industry fields like sports, robotic electronics, armaments, and textile ones, or production of audio-video equipment. Furthermore, addition of lithium, that has density of 0,53 g/cm3, reduces density of the resulting Mg-Li alloys to the same level as polymeric materials. On metallic matrix of magnesium alloys with lithium are also manufactured composites reinforced with e.g. ceramic fiber, which are used as a lightweight and resistant structure materials. Therefore, Mg-Li alloys become an alternative material assuring low density, improved ductility and corrosion resistance.The paper presents an attempt of implementation of the ATND method to monitoring of crystallization process of MCMgLi8Ca5 alloys.Investigated magnesium alloys were produced in the Foundry Research Institute. Registration of melting and crystallization processes wasmade with use of the ATND method. Results of the preliminary tests are shown in a graphical form.

  6. Exploiting Process-Related Advantages of Selective Laser Melting for the Production of High-Manganese Steel.

    Science.gov (United States)

    Haase, Christian; Bültmann, Jan; Hof, Jan; Ziegler, Stephan; Bremen, Sebastian; Hinke, Christian; Schwedt, Alexander; Prahl, Ulrich; Bleck, Wolfgang

    2017-01-11

    Metal additive manufacturing has strongly gained scientific and industrial importance during the last decades due to the geometrical flexibility and increased reliability of parts, as well as reduced equipment costs. Within the field of metal additive manufacturing methods, selective laser melting (SLM) is an eligible technique for the production of fully dense bulk material with complex geometry. In the current study, we addressed the application of SLM for processing a high-manganese TRansformation-/TWinning-Induced Plasticity (TRIP/TWIP) steel. The solidification behavior was analyzed by careful characterization of the as-built microstructure and element distribution using optical and scanning electron microscopy (SEM). In addition, the deformation behavior was studied using uniaxial tensile testing and SEM. Comparison with conventionally produced TRIP/TWIP steel revealed that elemental segregation, which is normally very pronounced in high-manganese steels and requires energy-intensive post processing, is reduced due to the high cooling rates during SLM. Also, the very fast cooling promoted ε- and α'-martensite formation prior to deformation. The superior strength and pronounced anisotropy of the SLM-produced material was correlated with the microstructure based on the process-specific characteristics.

  7. Microstructures and mechanical properties of Co-29Cr-6Mo alloy fabricated by selective laser melting process for dental applications.

    Science.gov (United States)

    Takaichi, Atsushi; Suyalatu; Nakamoto, Takayuki; Joko, Natsuka; Nomura, Naoyuki; Tsutsumi, Yusuke; Migita, Satoshi; Doi, Hisashi; Kurosu, Shingo; Chiba, Akihiko; Wakabayashi, Noriyuki; Igarashi, Yoshimasa; Hanawa, Takao

    2013-05-01

    The selective laser melting (SLM) process was applied to a Co-29Cr-6Mo alloy, and its microstructure, mechanical properties, and metal elution were investigated to determine whether the fabrication process is suitable for dental applications. The microstructure was evaluated using scanning electron microscopy with energy-dispersed X-ray spectroscopy (SEM-EDS), X-ray diffractometry (XRD), and electron back-scattered diffraction pattern analysis. The mechanical properties were evaluated using a tensile test. Dense builds were obtained when the input energy of the laser scan was higher than 400 J mm⁻³, whereas porous builds were formed when the input energy was lower than 150 J mm⁻³. The microstructure obtained was unique with fine cellular dendrites in the elongated grains parallel to the building direction. The γ phase was dominant in the build and its preferential orientation was confirmed along the building direction, which was clearly observed for the builds fabricated at lower input energy. Although the mechanical anisotropy was confirmed in the SLM builds due to the unique microstructure, the yield strength, UTS, and elongation were higher than those of the as-cast alloy and satisfied the type 5 criteria in ISO22764. Metal elution from the SLM build was smaller than that of the as-cast alloy, and thus, the SLM process for the Co-29Cr-6Mo alloy is a promising candidate for fabricating dental devices. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Exploiting Process-Related Advantages of Selective Laser Melting for the Production of High-Manganese Steel

    Directory of Open Access Journals (Sweden)

    Christian Haase

    2017-01-01

    Full Text Available Metal additive manufacturing has strongly gained scientific and industrial importance during the last decades due to the geometrical flexibility and increased reliability of parts, as well as reduced equipment costs. Within the field of metal additive manufacturing methods, selective laser melting (SLM is an eligible technique for the production of fully dense bulk material with complex geometry. In the current study, we addressed the application of SLM for processing a high-manganese TRansformation-/TWinning-Induced Plasticity (TRIP/TWIP steel. The solidification behavior was analyzed by careful characterization of the as-built microstructure and element distribution using optical and scanning electron microscopy (SEM. In addition, the deformation behavior was studied using uniaxial tensile testing and SEM. Comparison with conventionally produced TRIP/TWIP steel revealed that elemental segregation, which is normally very pronounced in high-manganese steels and requires energy-intensive post processing, is reduced due to the high cooling rates during SLM. Also, the very fast cooling promoted ε- and α’-martensite formation prior to deformation. The superior strength and pronounced anisotropy of the SLM-produced material was correlated with the microstructure based on the process-specific characteristics.

  9. Mechanical properties of melt-processed polymer blend of amorphous corn flour composite filler and styrene-butadiene rubber

    Science.gov (United States)

    The corn flour composite fillers were prepared by blending corn flour with rubber latex, dried, and cryogenically ground into powders, which were then melt-blended with rubber polymers in an internal mixer to form composites with enhanced mechanical properties. The composites prepared with melt-blen...

  10. Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

    International Nuclear Information System (INIS)

    Baldenebro-Lopez, F.J.; Herrera-Ramírez, J.M.; Arredondo-Rea, S.P.; Gómez-Esparza, C.D.; Martínez-Sánchez, R.

    2015-01-01

    Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying

  11. Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Baldenebro-Lopez, F.J. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Herrera-Ramírez, J.M. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Arredondo-Rea, S.P. [Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Gómez-Esparza, C.D. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Martínez-Sánchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico)

    2015-09-15

    Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying.

  12. Investigations on Temperature Fields during Laser Beam Melting by Means of Process Monitoring and Multiscale Process Modelling

    Directory of Open Access Journals (Sweden)

    J. Schilp

    2014-07-01

    Full Text Available Process monitoring and modelling can contribute to fostering the industrial relevance of additive manufacturing. Process related temperature gradients and thermal inhomogeneities cause residual stresses, and distortions and influence the microstructure. Variations in wall thickness can cause heat accumulations. These occur predominantly in filigree part areas and can be detected by utilizing off-axis thermographic monitoring during the manufacturing process. In addition, numerical simulation models on the scale of whole parts can enable an analysis of temperature fields upstream to the build process. In a microscale domain, modelling of several exposed single hatches allows temperature investigations at a high spatial and temporal resolution. Within this paper, FEM-based micro- and macroscale modelling approaches as well as an experimental setup for thermographic monitoring are introduced. By discussing and comparing experimental data with simulation results in terms of temperature distributions both the potential of numerical approaches and the complexity of determining suitable computation time efficient process models are demonstrated. This paper contributes to the vision of adjusting the transient temperature field during manufacturing in order to improve the resulting part's quality by simulation based process design upstream to the build process and the inline process monitoring.

  13. Corrosion Behavior in 3.5% NaCl Solutions of γ-TiAl Processed by Electron Beam Melting Process

    Directory of Open Access Journals (Sweden)

    Asiful Hossain Seikh

    2015-12-01

    Full Text Available In this work, the corrosion behavior of γ-TiAl alloy produced by electron beam melting (EBM process in 3.5% NaCl solution was reported. The study has been performed using potentiodynamic polarization resistance and electrochemical impedance spectroscopy techniques and complemented by scanning electron microscopy investigations. All measurements were carried out after different periods of alloy exposure in the chloride solutions and at different temperatures. The results showed that the EBM produced γ-TiAl alloy has excellent corrosion resistance confirmed by the high values of polarization resistance and the low values of corrosion current and corrosion rate. With increase in immersion time, the corrosion potential moved to a higher positive value with a decrease in corrosion current and corrosion rate, which suggests an improvement in corrosion resistance. On the other hand, the increase of temperature was found to significantly increase the corrosion of the processed γ-TiAl alloy.

  14. Magnetic separation technique for groundwater by five HTS melt-processed bulk magnets arranged in a line

    International Nuclear Information System (INIS)

    Oka, T.; Seki, H.; Kimura, T.; Mimura, D.; Fukui, S.; Ogawa, J.; Sato, T.; Ooizumi, M.; Fujishiro, H.; Hayashi, H.; Yokoyama, K.; Stiehler, C.

    2011-01-01

    A magnetic separation was practically conducted by 10-pole HTS bulk magnets. The HTS bulk magnets were activated to 2.5 T by feeding pulsed fields of 6 T. The separation ratio of actual groundwater exceeded 70% at less than 4.8 l/min. The flocks without magnetite powder were obviously attracted to the magnetic poles. A magnetic separation study for groundwater purification has been practically conducted by using the multi-pole magnet system. The magnetic pole was composed of 10 open magnetic spaces by arranging five HTS melt-processed bulk magnets in a line in a vacuum sheath. The individual bulk magnets were activated by feeding intense pulsed magnetic fields up to 6 T. The magnetic field distribution was estimated with respect to various pole arrangements. The actual groundwater samples of Sanjo City were processed so as to form large precipitates by adding the coagulant and pH controlling. The maximum separation ratio of the iron-bearing precipitates has exceeded over 70% when slurry water was exposed to 10 magnetic poles of up to 2.5 T at a flowing rate of less than 4.8 l/min. An obvious attraction of flocks to the magnetic poles was observed even when the water contains no magnetite powder at the flow rate of 1.01 l/min. This implies the validity of the multi-pole magnet system with respect to the actual application to water purification.

  15. A comparison of corrosion resistance of cobalt-chromium-molybdenum metal ceramic alloy fabricated with selective laser melting and traditional processing.

    Science.gov (United States)

    Zeng, Li; Xiang, Nan; Wei, Bin

    2014-11-01

    A cobalt-chromium-molybdenum alloy fabricated by selective laser melting is a promising material; however, there are concerns about the change in its corrosion behavior. The purpose of this study was to evaluate the changes in corrosion behavior of a cobalt-chromium-molybdenum alloy fabricated by the selective laser melting technique before and after ceramic firing, with traditional processing of cobalt-chromium-molybdenum alloy serving as a control. Two groups of specimens were designated as group selective laser melting and group traditional. For each group, 20 specimens with a cylindrical shape were prepared and divided into 4 cells: selective laser melting as-cast, selective laser melting fired in pH 5.0 and 2.5, traditional as-cast, and traditional fired in pH 5.0 and 2.5. Specimens were prepared with a selective laser melting system for a selective laser melting alloy and the conventional lost wax technique for traditional cast alloy. After all specimen surfaces had been wet ground with silicon carbide paper (1200 grit), each group of 10 specimens was put through a series of ceramic firing cycles. Microstructure, Vickers microhardness, surface composition, oxide film thickness, and corrosion behavior were examined for specimens before and after ceramic firing. Three-way ANOVA was used to evaluate the effect of porcelain firing and pH values on the corrosion behavior of the 2 alloys (α=.05). Student t tests were used to compare the Vickers hardness. Although porcelain firing changed the microstructure, microhardness, and x-ray photoelectron spectroscopy results, it showed no significant influence on the corrosion behavior of the selective laser melting alloy and traditional cast alloy (P>.05). No statistically significant influence was found on the corrosion behavior of the 2 alloys in different pH value solutions (P>.05). The porcelain firing process had no significant influence on the corrosion resistance results of the 2 alloys. Compared with traditional

  16. Processing of aluminum matrix composites by electroless plating and melt infiltration

    International Nuclear Information System (INIS)

    Leon, C.A.; Bourassa, A.-M.; Drew, R.A.L.

    2000-01-01

    Reduction of the SiC/ Al interaction and enhancement of wetting between reinforcements and molten aluminum was obtained by modifying the ceramic surface with deposition of nickel and copper coatings. The preparation of nickel- and copper-coated ceramic particles as precursors for MMC fabrication was studied. Al 2 O 3 and SiC powders were successfully coated with Ni and Cu using electroless metal plating. Uniform and continuous metal films were deposited on both, alumina and silicon carbide powders XRD showed that the Ni-P deposit was predominantly amorphous, while the copper deposit was essentially polycrystalline. Infiltration results showed that the use of the coated powders enhances the wettability between the matrix and ceramic phase when processing particulate MMCs by a vacuum infiltration technique, giving a porosity-free composite with a homogeneously distributed reinforcing phase. The coating promoted easy metal flow through the preform, compared to the non-infiltration behavior of the uncoated counterpart samples XRD microstructural analysis of the composites indicates the formation of intermetallic phases such as CuAl 2 , in the case of copper coating, and NiAl and NiAl 3 when nickel-coated powders are infiltrated. Metallization of the ceramics minimizes the interfacial reaction of the SiC/Al composites and promotes wetting of Al 2 O 3 reinforcements with liquid aluminum. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

  17. The effect of starch amylose content on the morphology andproperties of melt-processed butyl-etherified starch/poly[(butylenesuccinate)-co-adipate] blends

    CSIR Research Space (South Africa)

    Maubane, Lesego T

    2017-01-01

    Full Text Available In this study, butyl-etherified waxy and high amylose starches were melt-processed with biodegradable poly[(butylene succinate)-co-adipate] (PBSA) to improve the long-term stability of the starch-based materials. Butyl-etherification was believed...

  18. A numerical study of the influence of feeding polycrystalline silicon granules on melt temperature in the continuous Czochralski process

    Science.gov (United States)

    Ono, Naoki; Kida, Michio; Arai, Yoshiaki; Sahira, Kensho

    1993-09-01

    Temperature change was simulated using a solid body rotating melt model when solid polycrystalline silicon granules were supplied to a melt in a double-crucible method. Only heat conduction was considered in the analysis. The influence of the crucible rotation rates and of the initial temperature of the supplied silicon was investigated systematically and quantitatively. The influence of the crucible rotation rate was stronger than expected, which suggests that the crucible rotation rate cannot be lowered too much because of the possibility of the melt solidifying between the inner and outer crucibles.

  19. Stainless steels with low contents in residual elements for nitric acid environments. Influence of melting processes

    International Nuclear Information System (INIS)

    Desestret, A.; Gay, G.; Soulignac, P.

    1983-01-01

    Nitric acid solutions, as they are for instance employed in the chemical treatment of nuclear fuels, do not apparently pose any more corrosion problems and the safe use of the several steels is well documented. The most difficult corrosion problems are next those related to ''tunnel'' penetrations, in the hot-rolling direction (longitudinal). This phenomenon can be quite important such as to imperial complex structures. Up to the last few years, the only manner to eliminate such ''tunnel'' corrosions was to carry out special operations of remelting and refining under careful selected slag (Electro Slag Remelting or ESR). It turns out indeed that non metallic inclusions are the prime factors in this type of corrosion. Well adapted ladle refining processes made possible to obtain equivalent results at lower costs, while purity and cleanliness are improved to such a degree that a steel of type Cr 18 - Ni 10 thus produced exhibit a nearly absolute resistance to intergranular corrosion in the 14 N (65%) boiling nitric acid (the Huey test) whatever the ''sensitization'' treatment, between 1000 0 C and 600 0 C. In view of its very high tolerance to varied thermal cycles and of the near complete disappearance of any ''tunnel'' corrosion, such a steel is of great interest when complex parts are produced, by machining forged or rolled metal, which is then assembled by welding techniques or procedures which would be forbidden in the case of usual Cr 18 -Ni 10 steels. Similar improvements are also obtained on the two other special steels used in nitric environments: Cr 25 - Ni 20 - C [fr

  20. Development and Performance of a Highly Sensitive Model Formulation Based on Torasemide to Enhance Hot-Melt Extrusion Process Understanding and Process Development.

    Science.gov (United States)

    Evans, Rachel C; Kyeremateng, Samuel O; Asmus, Lutz; Degenhardt, Matthias; Rosenberg, Joerg; Wagner, Karl G

    2018-02-27

    The aim of this work was to investigate the use of torasemide as a highly sensitive indicator substance and to develop a formulation thereof for establishing quantitative relationships between hot-melt extrusion process conditions and critical quality attributes (CQAs). Using solid-state characterization techniques and a 10 mm lab-scale co-rotating twin-screw extruder, we studied torasemide in a Soluplus® (SOL)-polyethylene glycol 1500 (PEG 1500) matrix, and developed and characterized a formulation which was used as a process indicator to study thermal- and hydrolysis-induced degradation, as well as residual crystallinity. We found that torasemide first dissolved into the matrix and then degraded. Based on this mechanism, extrudates with measurable levels of degradation and residual crystallinity were produced, depending strongly on the main barrel and die temperature and residence time applied. In addition, we found that 10% w/w PEG 1500 as plasticizer resulted in the widest operating space with the widest range of measurable residual crystallinity and degradant levels. Torasemide as an indicator substance behaves like a challenging-to-process API, only with higher sensitivity and more pronounced effects, e.g., degradation and residual crystallinity. Application of a model formulation containing torasemide will enhance the understanding of the dynamic environment inside an extruder and elucidate the cumulative thermal and hydrolysis effects of the extrusion process. The use of such a formulation will also facilitate rational process development and scaling by establishing clear links between process conditions and CQAs.

  1. Investigation of Performance and Residual Stress Generation of AlSi10Mg Processed by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Lianfeng Wang

    2018-01-01

    Full Text Available During the selective laser melting (SLM process, the scanned layers are subjected to rapid thermal cycles. By working on the mechanical properties, residual stress, and microstructure, the high-temperature gradients can have significant effect on the proper functioning and the structural integrity of built parts. This work presents a comprehensive study on the scanning path type and preheating temperature for AlSi10Mg alloy during SLM. According to the results, SLM AlSi10Mg parts fabricated in chessboard scanning strategy have higher mechanical properties or at least comparable to the parts fabricated in uniformity scanning strategy. In the SLM processing, the residual stress in different parts of the specimen varies with temperature gradient, and the residual stress at the edge of the specimen is obviously larger than that at the center. Under the chessboard scanning and preheating temperature 160°C, the residual stress in each direction of the specimens reaches the minimum. Under different forming processes, the morphology of the microstructure is obviously different. With the increase of preheating temperature, the molten pool in the side surface is obviously elongated and highly unevenly distributed. From the coupling relationship between the residual stress and microstructure, it can be found that the microstructure of top surface is affected by residual stresses σx and σy. But the side surface is mainly governed by residual stress σy; moreover, the greater the residual stress, the more obvious the grain tilt. In the XY and XZ surfaces, the scanning strategy has little influence on the tilt angle of the grain. But, the tilt angle and morphology of the microstructure are obviously affected by the preheating temperature. The results show that the residual stresses can effectively change the properties of the materials under the combined influence of scanning strategy and preheating temperature.

  2. Development of cube textured Ni-5 at.%W alloy substrates for coated conductor application using a melting process

    International Nuclear Information System (INIS)

    Zhao Yue; Suo Hongli; Liu Min; Liu Danmin; Zhang Yingxiao; Zhou Meiling

    2006-01-01

    Biaxially textured Ni-5 at.%W substrates have been prepared by cold rolling, followed by three different annealing routes. In this paper, the processes of melting Ni and W metals, flat rolling, various annealing methods are described in detail. The Ni-5 at.%W tapes annealed under either high vacuum or flowing Ar (7% H 2 ) gas were characterized by X-ray pole figures, ODF, EBSD as well as AFM analysis. The texture analysis indicated that as fabricated tapes have a sharp cube texture formed after annealing at a wide temperature range of 800-1100 o C. The high quality of cube orientation on tapes was obtained after a two-step annealing (TSA), where the percentage of the cube texture component was as high as 93.5% within a misorientation angle smaller than 8 o from EBSD analysis. Furthermore, it was also observed that the number of twin boundaries in this tape decreased with respect to that of tapes annealed both in vacuum and one-step gas annealing. From AFM on 1 μm 2 areas, it was concluded that the roughness (RMS) on the tape surface reached 0.98 nm

  3. Electrical, Mechanical, and Thermal Properties of LDPE Graphene Nanoplatelets Composites Produced by Means of Melt Extrusion Process

    Directory of Open Access Journals (Sweden)

    Karolina Gaska

    2017-01-01

    Full Text Available Composites of LDPE filled with different amounts of graphene nanoplatelets (GnP were prepared in form of films by means of precoating technique and single screw melt-extrusion using two types of screws, compression and mixing. This manufacturing process imposes strong anisotropy on the sample’s morphology, in which the nanoplatelets become oriented along the extrusion direction. Such orientation of GnP in LDPE matrix is confirmed by scanning electron microscopy observations and it yields unique electrical properties. As compared to pure LDPE, significant reductions of the through-plane conductivity are found for the composites at relatively low electric fields (<20 kV/mm at low filler concentrations. Above the field level of 20 kV/mm, a crossover effect is observed that results in a strong field dependency of the conductivity where the non-linear behavior starts to dominate. Moreover, differential scanning calorimetry (DSC results indicate a decrease in polymer crystallinity of the composite matrix with increasing filler content, whereas thermogravimetric (TG analysis shows a slight increase in the material’s thermal stability. Application of GnP also leads to improvement of mechanical properties, manifested by the increase of Young’s modulus and tensile strength in both types of samples.

  4. Application of X-ray radioscopic methods for characterization of two-phase phenomena and solidification processes in metallic melts

    Science.gov (United States)

    Shevchenko, Natalia; Boden, Stefan; Eckert, Sven; Borin, Dmitry; Heinze, Michael; Odenbach, Stefan

    2013-03-01

    X-ray attenuation techniques are an important diagnostic tool for investigating liquid metal two-phase flows or solidification studies in metallic alloys. X-ray visualization enables a general, intuitive understanding of flow phenomena or pattern formation in opaque liquid metal systems. Real-time and in-situ observations of the density distribution within thin solidifying samples achieve a spatial resolution of a few microns and contribute significantly to an improved understanding of dendritic growth processes. Moreover, X-ray radioscopy is a useful tool for a non-invasive, in-situ visualization and characterization of gas bubbles in nontransparent melts or for observations of the formation of metal foams. In this paper we consider three different fields of application which are under intensive investigation at HZDR and TUD: the bottom-up solidification of Ga-In alloys under the influence of buoyancy-driven and electromagnetically driven convection, the injection of Ar gas into liquid GaInSn, the study of Al foams with respect to foam formation and the characterization of their internal structure.

  5. Influence of Y2BaCuO5 precipitates on the current density of melt processed YBa2Cu3Ox superconductor

    International Nuclear Information System (INIS)

    Salama, K.; Selvamanickam, V.

    1992-01-01

    YBa 2 Cu 3 O x superconductors fabricated by melt processing methods have been shown to exhibit current density around 10 5 A/cm 2 at 77 K. Since YBa 2 Cu 3 O x decomposes peritectically above 1000 C, more than 50 vol. % of Y 2 BaCuO 5 (211) precipitates are formed during the incongruent melting. Even under stringent slow cooling conditions, a significant amount of these precipitates remain unreacted with the liquid and are left embedded in the long 123 grains. The potential of these precipitates as flux pinning sites has been investigated extensively, but remains controversial. In this study, we have performed transport current density measurements on melt processed YBa 2 Cu 3 O x superconductor prepared with varying amount of 211 precipitates. The current density measurements were performed in magnetic fields up to 1.5 T at 77 K with the field aligned at different angles to the a-b plane. The results provided in this paper show that Jc decreases monotonically with increasing amount of 211, irrespective of the angle between the field and the a-b plane indicating the absence of significant pinning by 211 precipitates in melt processed YBa 2 Cu 3 O x superconductor

  6. Study of critical free-area ratio during the snow-melting process on pavement using low-temperature heating fluids

    International Nuclear Information System (INIS)

    Wang Huajun; Chen Zhihao

    2009-01-01

    Critical free-area ratio (CFR) is an interesting phenomenon during the snow-melting process on pavement using low-temperature heating fluids such as geothermal tail water and industrial waste water. This paper is performed to further investigate the mechanism of CFR and its influencing factors. A simplified theoretical model is presented to describe the heat and mass transfer process on pavement. Especially the variation of thermal properties and the capillary effect of snow layer are considered. Numerical computation shows that the above theoretical model is effective for the prediction of CFR during the snow-melting process. Furthermore, the mechanism of CFR is clarified in detail. CFR is independent of the layout of hydronic pipes, the fluid temperature, the idling time, and weather conditions. It is both the non-uniform temperature distribution and complicated porous structure of snow layer that lead to the occurrence of CFR. Besides, the influences of operation parameters including the fluid temperature, the idling time, the pipe spacing and buried depths on snow melting are analyzed, which are helpful for the next optimal design of snow-melting system

  7. Emerging melt quality control solution technologies for aluminium melt

    Directory of Open Access Journals (Sweden)

    Arturo Pascual, Jr

    2009-11-01

    Full Text Available The newly developed “MTS 1500” Melt Treatment System is performing the specifi cally required melt treatment operations like degassing, cleaning, modification and/or grain refinement by an automated process in one step and at the same location. This linked process is saving time, energy and metal losses allowing - by automated dosage of the melt treatment agents - the production of a consistent melt quality batch after batch. By linking the MTS Metal Treatment System with sensors operating on-line in the melt, i.e., with a hydrogen sensor “Alspek H”, a fully automated control of parts of the process chain like degassing is possible. This technology does guarantee a pre-specifi ed and documented melt quality in each melt treatment batch. Furthermore, to ensure that castings are consistent and predictable there is a growing realization that critical parameters such as metal cleanliness must be measured prior to casting. There exists accepted methods for measuring the cleanliness of an aluminum melt but these can be both slow and costly. A simple, rapid and meaningful method of measuring and bench marking the cleanliness of an aluminum melt has been developed to offer the foundry a practical method of measuring melt cleanliness. This paper shows the structure and performance of the integrated MTS melt treatment process and documents achieved melt quality standards after degassing, cleaning, modifi cation and grain refi nement operations under real foundry conditions. It also provides an insight on a melt cleanliness measuring device “Alspek MQ” to provide foundry men better tools in meeting the increasing quality and tighter specifi cation demand from the industry.

  8. Energy Saving Melting and Revert Reduction Technology: Improved Die Casting Process to Preserve the Life of the Inserts

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam, PI; Xuejun Zhu, Sr. Research Associate

    2012-09-30

    The goal of this project was to study the combined effects of die design, proper internal cooling and efficient die lubricants on die life. The project targeted improvements in die casting insert life by: Optomized Die Design for Reduced Surface Temperature: The life of die casting dies is significantly shorter when the die is exposed to elevated temperature for significant periods of time. Any die operated under conditions leading to surface temperature in excess of 1050oF undergoes structural changes that reduce its strength. Optimized die design can improve die life significantly. This improvement can be accomplished by means of cooling lines, baffles and bubblers in the die. A key objective of the project was to establish criteria for the minimal distance of the cooling lines from the surface. This effort was supported with alloys and machining by BohlerUddeholm, Dunn Steel, HH Stark and Rex Buckeye. In plant testing and evaluation was conducted as in-kind cost share at St. Clair Die Casting. The Uddeholm Dievar steel evaluated in this program showed superior resistance to thermal fatigue resistance. Based on the experimental evidence, cooling lines could be placed as close as 0.5" from the surface. Die Life Extension by Optimized Die Lubrication: The life of die casting dies is affected by additions made to its surface with the proper lubricants. These lubricants will protect the surface from the considerable temperature peaks that occur when the molten melt enters the die. Dies will reach a significantly higher temperature without this lubricant being applied. The amount and type of the lubricant are critical variables in the die casting process. However, these lubricants must not corrode the die surface. This effort was supported with alloys and machining by BohlerUddeholm, Dunn Steel, HH Stark and Rex Buckeye. In plant testing and evaluation was conducted as in-kind cost share at St. Clair Die Casting. Chem- Trend participated in the program with die

  9. Microbial processes in glaciers and permafrost. A literature study on microbiology affecting groundwater at ice sheet melting

    International Nuclear Information System (INIS)

    Hallbeck, Lotta

    2009-10-01

    A repository for spent nuclear fuel will remain for hundred thousands of years. During this period, several ice ages will most likely take place. To understand the effect of melt water from ice sheets on the repository, the microbiological processes of oxygen reduction has to be elucidated. This report is a compilation of the present knowledge about biological activity in glacier environments. These environments consist of many different parts which have their own biological character depending on the prevailing physical and chemical conditions. There are, for example, ice sheets and glaciers, glacial streams and rivers, soil and water beneath the ice, soil and water in front of and beside ice sheets and glacier and deep groundwater beneath the ice. The microbiological processes of importance are consumption of oxygen by aerobic microorganisms, anaerobic organisms and their reduced metabolites, like sulphide, acetate and methane, which can act as reducing agents in biological or chemical oxygen reduction. The lithotrophic type (inorganic energy source) of metabolism is important in these cold environments. There are also microbiological processes important to radionuclide transport and the production of complexing agents, biological colloids and biofilms. The study of microbial processes in glacier and ice sheet environments is still a young scientific niche. The studies have so far mostly been concentrated to ice surfaces and the subglacial environment. The most important findings from the literature study are as follows. Primary production is ongoing in snow cover and on ice surfaces of glaciers and ice sheets. The production is dependent on the location, because of temperature and solar radiation, but also on the prevailing state of the glacier. On surfaces and in the snow cover, heterotrophic microorganisms consume oxygen and organic material. In surface ice structures anaerobic conditions may occur. The subglacial environment is very active with several types

  10. Microbial processes in glaciers and permafrost. A literature study on microbiology affecting groundwater at ice sheet melting

    Energy Technology Data Exchange (ETDEWEB)

    Hallbeck, Lotta (Microbial Analytics Sweden AB, Moelnlycke (Sweden))

    2009-10-15

    A repository for spent nuclear fuel will remain for hundred thousands of years. During this period, several ice ages will most likely take place. To understand the effect of melt water from ice sheets on the repository, the microbiological processes of oxygen reduction has to be elucidated. This report is a compilation of the present knowledge about biological activity in glacier environments. These environments consist of many different parts which have their own biological character depending on the prevailing physical and chemical conditions. There are, for example, ice sheets and glaciers, glacial streams and rivers, soil and water beneath the ice, soil and water in front of and beside ice sheets and glacier and deep groundwater beneath the ice. The microbiological processes of importance are consumption of oxygen by aerobic microorganisms, anaerobic organisms and their reduced metabolites, like sulphide, acetate and methane, which can act as reducing agents in biological or chemical oxygen reduction. The lithotrophic type (inorganic energy source) of metabolism is important in these cold environments. There are also microbiological processes important to radionuclide transport and the production of complexing agents, biological colloids and biofilms. The study of microbial processes in glacier and ice sheet environments is still a young scientific niche. The studies have so far mostly been concentrated to ice surfaces and the subglacial environment. The most important findings from the literature study are as follows. Primary production is ongoing in snow cover and on ice surfaces of glaciers and ice sheets. The production is dependent on the location, because of temperature and solar radiation, but also on the prevailing state of the glacier. On surfaces and in the snow cover, heterotrophic microorganisms consume oxygen and organic material. In surface ice structures anaerobic conditions may occur. The subglacial environment is very active with several types

  11. MELTED BUTTER TECHNOLOGY DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    L. V. Golubeva

    2014-01-01

    Full Text Available Summary. Melted butter is made from dairy butter by rendering the fat phase. It has specific taste and aroma, high-calorie content and good assimilability. Defects of butter which appeared during the storage causes by the development of microbiological processes or by the chemical oxidation. On the development of these processes influence quality and composition of fresh butter, its physical structure, content of the increased amount of gas phase and content of heavy metals, storage conditions. Microbiological spoilage of butter occurs generally due to damage of plasma which is good environment for the development of microorganisms. Defects of microbiological origin include: unclean, sour, moldy, yeasty, cheesy, bitter taste. Defects of test and smell chemical origin are formed due to hydrolytic digestion of lipids. It's prevailed at long storage of butter in the conditions of freezing temperatures. It's picked out the following main processes of spoiling: souring, acidifying and sallowness. Often these processes take place simultaneously.It has been investigated melted butter with lactated additive. The latter improves the microbiological and toxicological safety, prolongs the storage condition of the products. Technological efficiency of the additives is achieved by a multilayer products formation from the inactive bound water, preventing microorganisms growth and by the barrier layer with lactate inhibiting hydrolytic reactions. Oil samples were obtained with the batch-type butter maker application, then they were melted and after that lactated additive were supplemented. It has been studied organoleptic and physico-chemical indices of the melted butter samples. The fatty-acid composition of melted butter were studied. Comparative analysis of fatty-acid composition of cow's milk fat and produced melted butter has shown their similarity. Also in the last sample there is increased weight fraction of linoleic and linolenic acids. The obtained

  12. Evaluating the Effect of Processing Parameters on Porosity in Electron Beam Melted Ti-6Al-4V via Synchrotron X-ray Microtomography

    Science.gov (United States)

    Cunningham, Ross; Narra, Sneha P.; Ozturk, Tugce; Beuth, Jack; Rollett, A. D.

    2016-03-01

    Electron beam melting (EBM) is one of the subsets of direct metal additive manufacturing (AM), an emerging manufacturing method that fabricates metallic parts directly from a three-dimensional (3D) computer model by the successive melting of powder layers. This family of technologies has seen significant growth in recent years due to its potential to manufacture complex components with shorter lead times, reduced material waste and minimal post-processing as a "near-net-shape" process, making it of particular interest to the biomedical and aerospace industries. The popular titanium alloy Ti-6Al-4V has been the focus of multiple studies due to its importance to these two industries, which can be attributed to its high strength to weight ratio and corrosion resistance. While previous research has found that most tensile properties of EBM Ti-6Al-4V meet or exceed conventional manufacturing standards, fatigue properties have been consistently inferior due to a significant presence of porosity. Studies have shown that adjusting processing parameters can reduce overall porosity; however, they frequently utilize methods that give insufficient information to properly characterize the porosity (e.g., Archimedes' method). A more detailed examination of the result of process parameter adjustments on the size and spatial distribution of gas porosity was performed utilizing synchrotron-based x-ray microtomography with a minimum feature resolution of 1.5 µm. Cross-sectional melt pool area was varied systematically via process mapping. Increasing melt pool area through the speed function variable was observed to significantly reduce porosity in the part.

  13. Process and plant for the processing of slag from aluminium scrap and waste melting, recovery of components thereof and treatment of gasses generated

    Energy Technology Data Exchange (ETDEWEB)

    Olper, M.; Corsini, T.; Fracchia, P.

    1990-08-28

    Aluminum scrap is generally melted with a saline flux which absorbs the residues in the scrap and which protects the molten aluminum from oxidation. After tapping out the aluminum from the furnace, a saline slag is formed which creates serious disposal problems in that traditional methods for processing this slag (hot water leaching to dissolve the salts) releases gases developed from the decomposition of residues in the slag. Hydrogen, methane, and ammonia are the major components of these gases, and minor components include highly toxic substances such as phosphine and hydrogen sulfides. An object of this invention is to propose a treatment plant for saline slag arising from the processing of aluminum scrap, in which hazardous products are not emitted. According to the invention, the slag is leached with water, the solution is filtered and concentrated for recovery of chlorides, and the gases developed during leaching are burnt with the addition of fuel in order to reach their self-ignition temperature. The combustion heat produced by combusting these gases is recovered, preferably in a venturi-type apparatus, and used to concentrate the leach solution produced from the slag. 1 fig.

  14. Thermally conductive, electrically insulating and melt-processable polystyrene/boron nitride nanocomposites prepared by in situ reversible addition fragmentation chain transfer polymerization

    International Nuclear Information System (INIS)

    Huang, Xingyi; Wang, Shen; Zhu, Ming; Yang, Ke; Jiang, Pingkai; Bando, Yoshio; Golberg, Dmitri; Zhi, Chunyi

    2015-01-01

    Thermally conductive and electrically insulating polymer/boron nitride (BN) nanocomposites are highly attractive for various applications in many thermal management fields. However, so far most of the preparation methods for polymer/BN nanocomposites have usually caused difficulties in the material post processing. Here, an in situ grafting approach is designed to fabricate thermally conductive, electrically insulating and post-melt processable polystyrene (PS)/BN nanosphere (BNNS) nanocomposites by initiating styrene (St) on the surface functionalized BNNSs via reversible addition fragmentation chain transfer polymerization. The nanocomposites exhibit significantly enhanced thermal conductivity. For example, at a St/BN feeding ratio of 5:1, an enhancement ratio of 1375% is achieved in comparison with pure PS. Moreover, the dielectric properties of the nanocomposites show a desirable weak dependence on frequency, and the dielectric loss tangent of the nanocomposites remains at a very low level. More importantly, the nanocomposites can be subjected to multiple melt processing to form different shapes. Our method can become a universal approach to prepare thermally conductive, electrically insulating and melt-processable polymer nanocomposites with diverse monomers and nanofillers. (paper)

  15. Microstructure Evolution and High-Temperature Compressibility of Modified Two-Step Strain-Induced Melt Activation-Processed Al-Mg-Si Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Chia-Wei Lin

    2016-05-01

    Full Text Available A two-step strain-induced melt activation (TS-SIMA process that omits the cold working step of the traditional strain-induced melt activation (SIMA process is proposed for 6066 Al-Mg-Si alloy to obtain fine, globular, and uniform grains with a short-duration salt bath. The results show that increasing the salt bath temperature and duration leads to a high liquid phase fraction and a high degree of spheroidization. However, an excessive salt bath temperature leads to rapid grain growth and generates melting voids. The initial degree of dynamic recrystallization, which depends on the extrusion ratio, affects the globular grain size. With an increasing extrusion ratio, the dynamic recrystallization becomes more severe and the dynamic recrystallized grain size becomes smaller. It results in the globular grains becomes smaller. The major growth mechanism of globular grains is Ostwald ripening. Furthermore, high-temperature compressibility can be improved by the TS-SIMA process. After a 4 min salt bath at 620 °C, the high-temperature compression ratio become higher than that of a fully annealed alloy. The results show that the proposed TS-SIMA process has great potential.

  16. Predictive modeling, simulation, and optimization of laser processing techniques: UV nanosecond-pulsed laser micromachining of polymers and selective laser melting of powder metals

    Science.gov (United States)

    Criales Escobar, Luis Ernesto

    One of the most frequently evolving areas of research is the utilization of lasers for micro-manufacturing and additive manufacturing purposes. The use of laser beam as a tool for manufacturing arises from the need for flexible and rapid manufacturing at a low-to-mid cost. Laser micro-machining provides an advantage over mechanical micro-machining due to the faster production times of large batch sizes and the high costs associated with specific tools. Laser based additive manufacturing enables processing of powder metals for direct and rapid fabrication of products. Therefore, laser processing can be viewed as a fast, flexible, and cost-effective approach compared to traditional manufacturing processes. Two types of laser processing techniques are studied: laser ablation of polymers for micro-channel fabrication and selective laser melting of metal powders. Initially, a feasibility study for laser-based micro-channel fabrication of poly(dimethylsiloxane) (PDMS) via experimentation is presented. In particular, the effectiveness of utilizing a nanosecond-pulsed laser as the energy source for laser ablation is studied. The results are analyzed statistically and a relationship between process parameters and micro-channel dimensions is established. Additionally, a process model is introduced for predicting channel depth. Model outputs are compared and analyzed to experimental results. The second part of this research focuses on a physics-based FEM approach for predicting the temperature profile and melt pool geometry in selective laser melting (SLM) of metal powders. Temperature profiles are calculated for a moving laser heat source to understand the temperature rise due to heating during SLM. Based on the predicted temperature distributions, melt pool geometry, i.e. the locations at which melting of the powder material occurs, is determined. Simulation results are compared against data obtained from experimental Inconel 625 test coupons fabricated at the National

  17. The influence of oxide on the electrochemical processes in K2NbF7-NaCl-KCl melts

    DEFF Research Database (Denmark)

    Lantelme, F.; Berghoute, Y.; Barner, Jens H. Von

    1995-01-01

    Transient electrochemical techniques showed that in NaCl-KCl melts the reduction of K2NbF7 occurs through atwo-step reaction Nb(V) --> Nb(IV) --> Nb. When oxide ions were introduced, cyclic voltammetry indicated that the wavescorresponding to reduction of the complex NbF72- progressively...

  18. Effect of strain rate on mechanical properties of melt-processed soy flour composite filler and styrene-butadiene blends

    Science.gov (United States)

    Polymer composites were prepared by melt-mixing polymer and soy flour composite fillers in an internal mixer. Soy flour composite fillers were prepared by blending aqueous dispersion of soy flour with styrene-butadiene rubber latex, dried, and cryogenically ground into powders. Upon crosslinking, th...

  19. The Impact of Hydrodynamics in Erosion - Deposition Process in Can Gio Mangrove Biosphere Reserve, South Viet Nam

    Science.gov (United States)

    Vo-Luong, H. P.

    2014-12-01

    Can Gio Mangrove Biosphere Reserve is always considered as a friendly green belt to protect and bring up the habitants. However, recently some mangrove areas in the Dong Tranh estuary are being eroded seriously. Based on the field measurements in SW and NE monsoons as well as data of topography changes in 10 years, it is proved that hydrodynamics of waves, tidal currents and riverine currents are the main reasons for erosion-deposition processes at the studied site. The erosion-deposition process changes due to monsoon. The analysed results show that high waves and tidal oscillation cause the increase of the erosion rate in NE monsoon. However, high sediment deposition occurs in SW monsoon due to weak waves and more alluvium from upstream. Many young mangrove trees grow up and develop in the SW monsoon. From the research, it is strongly emphasized the role of mangrove forests in soil retention and energy dissipation.

  20. Melting of contaminated metallic waste

    International Nuclear Information System (INIS)

    Lee, Y.-S.; Cheng, S.-Y.; Kung, H.-T.; Lin, L.-F.

    2004-01-01

    Approximately 100 tons of contaminated metallic wastes were produced each year due to maintenance for each TPC's nuclear power reactor and it was roughly estimated that there will be 10,000 tons of metallic scraps resulted from decommissioning of each reactor in the future. One means of handling the contaminated metal is to melt it. Melting process owns not only volume reduction which saves the high cost of final disposal but also resource conservation and recycling benefits. Melting contaminated copper and aluminum scraps in the laboratory scale have been conducted at INER. A total of 546 kg copper condenser tubes with a specific activity of about 2.7 Bq/g was melted in a vacuum induction melting facility. Three types of products, ingot, slag and dust were derived from the melting process, with average activities of 0.10 Bq/g, 2.33 Bq/g and 84.3 Bq/g respectively. After the laboratory melting stage, a pilot plant with a 500 kg induction furnace is being designed to melt the increasingly produced contaminated metallic scraps from nuclear facilities and to investigate the behavior of different radionuclides during melting. (author)

  1. Anionic Pt in Silicate Melts at Low Oxygen Fugacity: Speciation, Partitioning and Implications for Core Formation Processes on Asteroids

    Science.gov (United States)

    Medard, E.; Martin, A. M.; Righter, K.; Malouta, A.; Lee, C.-T.

    2017-01-01

    Most siderophile element concentrations in planetary mantles can be explained by metal/ silicate equilibration at high temperature and pressure during core formation. Highly siderophile elements (HSE = Au, Re, and the Pt-group elements), however, usually have higher mantle abundances than predicted by partitioning models, suggesting that their concentrations have been set by late accretion of material that did not equilibrate with the core. The partitioning of HSE at the low oxygen fugacities relevant for core formation is however poorly constrained due to the lack of sufficient experimental constraints to describe the variations of partitioning with key variables like temperature, pressure, and oxygen fugacity. To better understand the relative roles of metal/silicate partitioning and late accretion, we performed a self-consistent set of experiments that parameterizes the influence of oxygen fugacity, temperature and melt composition on the partitioning of Pt, one of the HSE, between metal and silicate melts. The major outcome of this project is the fact that Pt dissolves in an anionic form in silicate melts, causing a dependence of partitioning on oxygen fugacity opposite to that reported in previous studies.

  2. Study of hybrid laser / MAG welding process: characterization of the geometry and the hydrodynamics of the melt pool and development of a 3D thermal model

    International Nuclear Information System (INIS)

    Le Guen, E.

    2010-11-01

    Hybrid laser/MIG-MAG welding shows high advantages compared to laser welding or GMAW arc welding used separately. Thanks to this process, higher productivity can be gained through higher welding speed, higher squeeze tolerance moreover possible improvement of the metallurgical properties of the weld seam can be obtained. However, many operating parameters have to be set up in order to achieve optimal process. The complex physical phenomena, which govern welding process, have to be understood in order to use efficiently this technique in mass production. Understanding of these phenomena is also necessary to program numerical simulations which fit to this process. In the first step, experimental studies have been carried out with GMAW, laser and hybrid welding on samples of S355 steel. Influence of operating parameters has been analyzed through films performed with speed camera and macro-graphies of weld seam cross section. Surface deformations of the melt pool, induced by the arc pressure, weld pool length, droplet detachment and welding speed, have been analyzed precisely from images of the surface melt pool. In a second step, a numerical model was developed using the COMSOL Multiphysics software for MAG, laser and hybrid laser/MAG welding processes. A 3D quasi-stationary model has been calculated from the temperature field within the metal. The originality of the MAG and hybrid model lies in the prediction of the melt pool surface profile used to determine the 3D geometry, by taking into account the material input. The influence of different parameters such as arc power and speed welding on the efficiency as well as the distribution radius of the arc power and the arc pressure are analyzed through validations with different experimental results and different calculation configurations. (author)

  3. Role of melt percentage on characteristics of Al-Zn-Mg/3 wt.% Al2O3 nanostructured composite modified through semi-solid thermomechanical processing

    Science.gov (United States)

    Hajizamani, Mohsen; Alizadeh, Mostafa; Alizadeh, Ali; Jenabali-Jahromi, Seyed Ahmad

    2018-02-01

    A thermomechanical processing (TMP) method was employed to modify the characteristics of Al-Zn-Mg/3 wt% Al2O3 composite including the microstructure and the mechanical properties. The composite powders were subsequently cold pressed at 115 MPa and solid state sintered at 550 °C for 90 min under argon atmosphere. The TMP was then performed on the samples consisting of an additional cold pressing at 250 MPa followed by a partial remelting stage in the semi-solid state for 30 min under argon atmosphere. Four different temperatures corresponding to four percentages of melt content were chosen to apply in the TMP to study the role of the melt content on the microstructure and mechanical properties of the modified samples. The observations obtained from the characterizations and mechanical tests showed that drastic alteration in the solid sintered microstructure occurred by reducing the porosity level and creating a solidified network as grain boundaries. However, with increasing the melt percentage up to 20%, decreasing the average grain diameter along with increasing the microhardness and compressive strength was observed.

  4. Constraining Open-System Processes in the Generation of Basaltic Magma Using 87Sr/86Sr of Individual Minerals and Melt Inclusions, Pisgah Crater, Ca

    Science.gov (United States)

    Ramos, F. C.; Wolff, J. A.

    2002-12-01

    Basaltic magmas have been extensively used to infer the geochemical nature of mantle sources. Studies which make such inferences typically focus on basalts that are characterized by assumed primary magma characteristics such as high MgO contents. Such characteristics are typically used as justification to discount or suggest only a minimal influence of open-system modifications, such as those resulting from crustal assimilation. Often, very little effort is made to more thoroughly eliminate this possibility because it is very difficult to identify and constrain such effects especially if the assimilated crust is mafic in character. Alkali basalts and hawaiities erupted at Pisgah Crater in the Mojave Desert of California result from open-system processes yet still retain high MgO (6-8%) contents. The specific processes responsible for extensive trace element and isotopic variations in these basalts, however, are in dispute. Glazner et al. (1991) suggest that Pisgah Crater trace element and isotopic variations originate from assimilation of mafic crust while Reiners (2002) suggests that such variations result from mixing of mantle-derived garnet peridotite and garnet pyroxenite magmas. Large 87Sr/86Sr variations among and within individual plagioclase, clinopyroxene, amphibole, groundmass, and melt inclusions in olivine attest to the effects of open-system processes and indicate a complex mixing process (i.e., not two-component mixing) that occurred up to the time of eruption (Ramos et al, in prep). 87Sr/86Sr of minerals indicate that early and intermediate erupted lavas retain relatively uncontaminated signatures while the latest erupted lavas reflect much higher 87Sr/86Sr, consistent with contamination at crustal pressures (i.e., within the plagioclase stability field). Major element compositions of melt inclusions hosted in olivine confirm the presence of highly evolved magmas (e.g., MgO: 0.5 to 3%, SiO2: 52-57%) in later erupted lavas. Whole grain olivine

  5. Thermodynamics of the melting process in Au nano-clusters: Phenomenology, energy, entropy and quasi-chemical modeling

    Science.gov (United States)

    Bertoldi, Dalía S.; Millán, Emmanuel N.; Guillermet, Armando Fernández

    2017-12-01

    The paper presents a thermodynamic study of the melting transition in Au nano-clusters with a number of atoms (N) in the range 103 means of a formalism involving an isomerization-type reaction between the atoms in the SPL and the LPL is explored. To this aim, an equilibrium constant (Keq) involving the concentration of such types of atoms is introduced. Finally, it is shown that a thermodynamic, van't Hoff analysis of the size-dependence of Keq yields values of the T0 temperature which are in very good agreement with those obtained from the energy and entropy values.

  6. Physics-based simulation modeling and optimization of microstructural changes induced by machining and selective laser melting processes in titanium and nickel based alloys

    Science.gov (United States)

    Arisoy, Yigit Muzaffer

    Manufacturing processes may significantly affect the quality of resultant surfaces and structural integrity of the metal end products. Controlling manufacturing process induced changes to the product's surface integrity may improve the fatigue life and overall reliability of the end product. The goal of this study is to model the phenomena that result in microstructural alterations and improve the surface integrity of the manufactured parts by utilizing physics-based process simulations and other computational methods. Two different (both conventional and advanced) manufacturing processes; i.e. machining of Titanium and Nickel-based alloys and selective laser melting of Nickel-based powder alloys are studied. 3D Finite Element (FE) process simulations are developed and experimental data that validates these process simulation models are generated to compare against predictions. Computational process modeling and optimization have been performed for machining induced microstructure that includes; i) predicting recrystallization and grain size using FE simulations and the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model, ii) predicting microhardness using non-linear regression models and the Random Forests method, and iii) multi-objective machining optimization for minimizing microstructural changes. Experimental analysis and computational process modeling of selective laser melting have been also conducted including; i) microstructural analysis of grain sizes and growth directions using SEM imaging and machine learning algorithms, ii) analysis of thermal imaging for spattering, heating/cooling rates and meltpool size, iii) predicting thermal field, meltpool size, and growth directions via thermal gradients using 3D FE simulations, iv) predicting localized solidification using the Phase Field method. These computational process models and predictive models, once utilized by industry to optimize process parameters, have the ultimate potential to improve performance of

  7. Solidification observations and sliding wear behavior of vacuum arc melting processed Ni–Al–TiC composites

    International Nuclear Information System (INIS)

    Karantzalis, A.E.; Lekatou, A.; Tsirka, K.

    2012-01-01

    Monolithic Ni 3 Al and Ni–25 at.%Al intermetallic matrix TiC-reinforced composites were successfully produced by vacuum arc melting. TiC crystals were formed through a dissolution–reprecipitation mechanism and their final morphology is explained by means of a) Jackson's classical nucleation and growth phenomena and b) solidification rate considerations. The TiC presence altered the matrix microconstituents most likely due to specific melt–particle interactions and crystal plane epitaxial matching. TiC particles caused a significant decrease on the specific wear rate of the monolithic Ni 3 Al alloy and the possible wear mechanisms are approached by means of a) surface oxidation, b) crack/flaws formation, c) material detachment and d) debris–counter surfaces interactions. - Highlights: ► Vacuum arc melting (VAM) of Ni-Al based intermetallic matrix composite materials. ► Solidification phenomena examination. ► TiC crystal formation and growth mechanisms. ► Sliding wear examination.

  8. Bioactive glass-ceramic coatings prepared by pulsed laser deposition from RKKP targets (sol-gel vs melt-processing route)

    Energy Technology Data Exchange (ETDEWEB)

    Rau, J.V., E-mail: giulietta.rau@ism.cnr.it [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Teghil, R. [Universita della Basilicata, Dipartimento di Chimica ' A.M. Tamburro' , Via dell' Ateneo Lucano, 10-85100 Potenza (Italy); CNR-IMIP U.O.S. di Potenza, Zona Industriale di Tito scalo (PZ) (Italy); Fosca, M. [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Universita di Roma ' La Sapienza' , Dipartimento di Chimica, Piazzale Aldo Moro, 5-00185 Rome (Italy); De Bonis, A. [Universita della Basilicata, Dipartimento di Chimica ' A.M. Tamburro' , Via dell' Ateneo Lucano, 10-85100 Potenza (Italy); CNR-IMIP U.O.S. di Potenza, Zona Industriale di Tito scalo (PZ) (Italy); Cacciotti, I.; Bianco, A. [Universita di Roma ' Tor Vergata' , Dipartimento di Ingegneria Industriale, UR INSTM ' Roma Tor Vergata' , Via del Politecnico, 1-00133 Rome (Italy); Albertini, V. Rossi [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Caminiti, R. [Universita di Roma ' La Sapienza' , Dipartimento di Chimica, Piazzale Aldo Moro, 5-00185 Rome (Italy); Ravaglioli, A. [Parco Torricelli delle Arti e delle Scienze, Via Granarolo, 64-48018 Faenza (Ra) (Italy)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Bioactive glass-ceramic coatings for bone tissue repair and regeneration. Black-Right-Pointing-Pointer Pulsed Lased Deposition allowed congruent transfer of target composition to coating. Black-Right-Pointing-Pointer Target was prepared by sol-gel process suitable for compositional tailoring. Black-Right-Pointing-Pointer Titanium, widely used for orthopaedics and dental implants, was used as substrate. Black-Right-Pointing-Pointer The physico-chemical properties of the prepared coatings are reported. -- Abstract: The deposition of innovative glass-ceramic composition (i.e. RKKP) coatings by Pulsed Lased Deposition (PLD) technique is reported. RKKP was synthesised following two methodologies: melt-processing and sol-gel, the latter being particularly suitable to tailor the compositional range. The PLD advantage with respect to other deposition techniques is the congruent transfer of the target composition to the coating. The physico-chemical properties of films were investigated by Scanning Electron and Atomic Force Microscopies, Fourier Transform Infrared Spectroscopy, Angular and Energy Dispersive X-ray Diffraction, and Vickers microhardness. The deposition performed at 12 J/cm{sup 2} and 500 Degree-Sign C allows to prepare crystalline films with the composition that replicates rather well that of the initial targets. The 0.6 {mu}m thin melt-processing RKKP films, possessing the hardness of 25 GPa, and the 4.3 {mu}m thick sol-gel films with the hardness of 17 GPa were obtained.

  9. Bioactive glass–ceramic coatings prepared by pulsed laser deposition from RKKP targets (sol–gel vs melt-processing route)

    International Nuclear Information System (INIS)

    Rau, J.V.; Teghil, R.; Fosca, M.; De Bonis, A.; Cacciotti, I.; Bianco, A.; Albertini, V. Rossi; Caminiti, R.; Ravaglioli, A.

    2012-01-01

    Highlights: ► Bioactive glass–ceramic coatings for bone tissue repair and regeneration. ► Pulsed Lased Deposition allowed congruent transfer of target composition to coating. ► Target was prepared by sol–gel process suitable for compositional tailoring. ► Titanium, widely used for orthopaedics and dental implants, was used as substrate. ► The physico-chemical properties of the prepared coatings are reported. -- Abstract: The deposition of innovative glass–ceramic composition (i.e. RKKP) coatings by Pulsed Lased Deposition (PLD) technique is reported. RKKP was synthesised following two methodologies: melt-processing and sol–gel, the latter being particularly suitable to tailor the compositional range. The PLD advantage with respect to other deposition techniques is the congruent transfer of the target composition to the coating. The physico-chemical properties of films were investigated by Scanning Electron and Atomic Force Microscopies, Fourier Transform Infrared Spectroscopy, Angular and Energy Dispersive X-ray Diffraction, and Vickers microhardness. The deposition performed at 12 J/cm 2 and 500 °C allows to prepare crystalline films with the composition that replicates rather well that of the initial targets. The 0.6 μm thin melt-processing RKKP films, possessing the hardness of 25 GPa, and the 4.3 μm thick sol–gel films with the hardness of 17 GPa were obtained.

  10. Drop-on-Demand System for Manufacturing of Melt-based Solid Oral Dosage: Effect of Critical Process Parameters on Product Quality.

    Science.gov (United States)

    Içten, Elçin; Giridhar, Arun; Nagy, Zoltan K; Reklaitis, Gintaras V

    2016-04-01

    The features of a drop-on-demand-based system developed for the manufacture of melt-based pharmaceuticals have been previously reported. In this paper, a supervisory control system, which is designed to ensure reproducible production of high quality of melt-based solid oral dosages, is presented. This control system enables the production of individual dosage forms with the desired critical quality attributes: amount of active ingredient and drug morphology by monitoring and controlling critical process parameters, such as drop size and product and process temperatures. The effects of these process parameters on the final product quality are investigated, and the properties of the produced dosage forms characterized using various techniques, such as Raman spectroscopy, optical microscopy, and dissolution testing. A crystallization temperature control strategy, including controlled temperature cycles, is presented to tailor the crystallization behavior of drug deposits and to achieve consistent drug morphology. This control strategy can be used to achieve the desired bioavailability of the drug by mitigating variations in the dissolution profiles. The supervisor control strategy enables the application of the drop-on-demand system to the production of individualized dosage required for personalized drug regimens.

  11. Numerical Study on the Thermal Performance of a Shell and Tube Phase Change Heat Storage Unit during Melting Process

    Directory of Open Access Journals (Sweden)

    Wei Li

    2014-11-01

    Full Text Available This work presents a numerical study of the thermal performance in a shell and tube phase change heat storage unit. Paraffin wax as phase change material (PCM is filled in the shell space. The heat transfer fluids (HTFs: air and water flow through the tube and transfer the heat to PCM. A mathematical model involving HTF and PCM is developed to analyze the thermal performance of the phase change heat storage unit and is validated with experimental data. Numerical investigation is conducted to evaluate the effect of HTF inlet velocity on the HTF outlet temperature, Nu, and melt fraction when air or water is used as HTF. Results indicate that the air inlet velocity has a great effect on the air outlet temperature and heat transfer rate, and the water inlet velocity has little effect on the water outlet temperature. The investigated results can provide a reference for designing phase change heat storage system.

  12. Noble gas solubility in silicate melts:a review of experimentation and theory, and implications regarding magma degassing processes

    Directory of Open Access Journals (Sweden)

    A. Paonita

    2005-06-01

    Full Text Available Noble gas solubility in silicate melts and glasses has gained a crucial role in Earth Sciences investigations and in the studies of non-crystalline materials on a micro to a macro-scale. Due to their special geochemical features, noble gases are in fact ideal tracers of magma degassing. Their inert nature also allows them to be used to probe the structure of silicate melts. Owing to the development of modern high pressure and temperature technologies, a large number of experimental investigations have been performed on this subject in recent times. This paper reviews the related literature, and tries to define our present state of knowledge, the problems encountered in the experimental procedures and the theoretical questions which remain unresolved. Throughout the manuscript I will also try to show how the thermodynamic and structural interpretations of the growing experimental dataset are greatly improving our understanding of the dissolution mechanisms, although there are still several points under discussion. Our improved capability of predicting noble gas solubilities in conditions closer to those found in magma has allowed scientists to develop quantitative models of magma degassing, which provide constraints on a number of questions of geological impact. Despite these recent improvements, noble gas solubility in more complex systems involving the main volatiles in magmas, is poorly known and a lot of work must be done. Expertise from other fields would be extremely valuable to upcoming research, thus focus should be placed on the structural aspects and the practical and commercial interests of the study of noble gas solubility.

  13. Influence of processing medium on frictional wear properties of ball bearing steel prepared by laser surface melting coupled with bionic principles

    International Nuclear Information System (INIS)

    Zhou Hong; Wang Chengtao; Guo Qingchun; Yu Jiaxiang; Wang Mingxing; Liao Xunlong; Zhao Yu; Ren Luquan

    2010-01-01

    Coupling with bionic principles, an attempt to improve the wear resistance of ball bearing steel (GCr15) with biomimetic units on the surface was made using a pulsed Nd: YAG laser. Air and water film was employed as processing medium, respectively. The microstructures of biomimeitc units were examined by scanning electron microscope and X-ray diffraction was used to describe the microstructure and identify the phases as functions of different mediums as well as water film with different thicknesses. The results indicated that the microstructure zones in the biomimetic specimens processed with water film were more refined and had better wear resistance increased by 55.8% in comparison with that processed in air; a significant improvement in microhardness was achieved by laser surface melting. The application of water film provided considerable microstructural changes and much more regular grain shape in biomimetic units, which played a key role in improving the wear resistance of ball bearing steel.

  14. Tuning the processability, morphology and biodegradability of clay incorporated PLA/LLDPE blends via selective localization of nanoclay induced by melt mixing sequence

    Directory of Open Access Journals (Sweden)

    S. H. Jafari

    2013-01-01

    Full Text Available Polylactic acid (PLA/linear low density polyethylene (LLDPE blend nanocomposites based on two different commercial-grade nanoclays, Cloisite® 30B and Cloisite® 15A, were produced via different melt mixing procedures in a counter-rotating twin screw extruder. The effects of mixing sequence and clay type on morphological and rheological behaviors as well as degradation properties of the blends were investigated. The X-ray diffraction (XRD results showed that generally the level of exfoliation in 30B based nanocomposites was better than 15A based nanocomposites. In addition, due to difference in hydrophilicity and kind of modifiers in these two clays, the effect of 30B on refinement of dispersed phase and enhancement of biodegradability of PLA/LLDPE blend was much more remarkable than that of 15A nanoclay. Unlike the one step mixing process, preparation of nanocomposites via a two steps mixing process improved the morphology. Based on the XRD and TEM (transmission electron microscopic results, it is found that the mixing sequence has a remarkable influence on dispersion and localization of the major part of 30B nanoclay in the PLA matrix. Owing to the induced selective localization of nanoclays in PLA phase, the nanocomposites prepared through a two steps mixing sequence exhibited extraordinary biodegradability, refiner morphology and better melt elasticity.

  15. Development of crystal texture in R-lean RFeCoNbB (R = Nd, Pr) alloy during melt spinning processes

    International Nuclear Information System (INIS)

    Li, Wei; Li, Lanlan; Liu, Yanguo; Zhang, Xiangyi

    2012-01-01

    Highlights: ► We study the texture development during the melt spinning processes of R-lean alloys. ► A strong (0 0 l) texture parallel to the ribbon plane for (Nd,Pr) 2 Fe 14 B is obtained. ► The texture for R 2 Fe 14 B crystals can develop by a seeding effect of α-Fe texture. ► The anisotropic nanocomposite magnet yields M r = 0.78M s and large (BH) max = 25.2 MGOe. - Abstract: The formation of crystal texture of R 2 Fe 14 B nanocrystals in R–Fe–B (R = rare earth) alloys with low R content ( 2 Fe 14 B nanocrystals during the melt spinning processes of Nd 3.6 Pr 5.4 Fe 80 Co 3 NbB 7 by effectively employing the seeding effect of α-Fe nanocrystal texture. The (Nd,Pr) 2 Fe 14 B nanocrystals produced from the R-lean alloy at a wheel speed of 18 m/s show a strong (0 0 l) texture parallel to the ribbon plane, which yields a high remanence M r = 0.78M s and a large energy product (BH) max = 25.2 MGOe for the α-Fe/(Nd,Pr) 2 Fe 14 B nanocomposite ribbons. The present study provides a promising approach to prepare anisotropic nanocomposite magnets from R-lean alloys.

  16. Micro-scale prediction method for API-solubility in polymeric matrices and process model for forming amorphous solid dispersion by hot-melt extrusion.

    Science.gov (United States)

    Bochmann, Esther S; Neumann, Dirk; Gryczke, Andreas; Wagner, Karl G

    2016-10-01

    A new predictive micro-scale solubility and process model for amorphous solid dispersions (ASDs) by hot-melt extrusion (HME) is presented. It is based on DSC measurements consisting of an annealing step and a subsequent analysis of the glass transition temperature (Tg). The application of a complex mathematical model (BCKV-equation) to describe the dependency of Tg on the active pharmaceutical ingredient (API)/polymer ratio, enables the prediction of API solubility at ambient conditions (25°C). Furthermore, estimation of the minimal processing temperature for forming ASDs during HME trials could be defined and was additionally confirmed by X-ray powder diffraction data. The suitability of the DSC method was confirmed with melt rheological trials (small amplitude oscillatory system). As an example, ball milled physical mixtures of dipyridamole, indomethacin, itraconazole and nifedipine in poly(vinylpyrrolidone-co-vinylacetate) (copovidone) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus®) were used. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Bubble Formation within Filaments of Melt-Processed Bi2212 wires and its strongly negative effect on the Critical Current Density

    CERN Document Server

    Kametani, F; Jiang, J; Scheuerlein, C; Malagoli, A; Di Michiel, M; Huang, Y; Miao, H; Parrell, J A; Hellstrom, E E; Larbalestier, D C

    2011-01-01

    Most studies of Bi2Sr2CaCu2Ox (Bi2212) show that the critical current density Jc is limited by the connectivity of the filaments, but what determines the connectivity is still elusive. Here we report on the role played by filament porosity in limiting Jc. By a microstructural investigation of wires quenched from the melt state, we find that porosity in the unreacted wire agglomerates into bubbles that segment the Bi2212 melt within the filaments into discrete sections. These bubbles do not disappear during subsequent processing because they are only partially filled by Bi2212 grains as the Bi2212 forms on cooling. Correlating the microstructure of quenched wires to their final, fully processed Jc values shows an inverse relation between Jc and bubble density. Bubbles are variable between conductors and perhaps from sample to sample, but they occur frequently and almost completely fill the filament diameter, so they exert a strongly variable but always negative effect on Jc. Bubbles reduce the continuous Bi221...

  18. Surface Roughness of a 3D-Printed Ni-Cr Alloy Produced by Selective Laser Melting: Effect of Process Parameters.

    Science.gov (United States)

    Hong, Min-Ho; Son, Jun Sik; Kwon, Tae-Yub

    2018-03-01

    The selective laser melting (SLM) process parameters, which directly determine the melting behavior of the metallic powders, greatly affect the nanostructure and surface roughness of the resulting 3D object. This study investigated the effect of various laser process parameters (laser power, scan rate, and scan line spacing) on the surface roughness of a nickel-chromium (Ni-Cr) alloy that was three-dimensionally (3D) constructed using SLM. Single-line formation tests were used to determine the optimal laser power of 200 W and scan rate of 98.8 mm/s, which resulted in beads with an optimal profile. In the subsequent multi-layer formation tests, the 3D object with the smoothest surface (Ra = 1.3 μm) was fabricated at a scan line spacing of 60 μm (overlap ratio = 73%). Narrow scan line spacing (and thus large overlap ratios) was preferred over wide scan line spacing to reduce the surface roughness of the 3D body. The findings of this study suggest that the laser power, scan rate, and scan line spacing are the key factors that control the surface quality of Ni-Cr alloys produced by SLM.

  19. Depolymerization of post-consumer PET with multifunctional alcohol through melt processing; Despolimerizacao de PET pos-consumo com alcool multifuncional atraves de processamento por fusao

    Energy Technology Data Exchange (ETDEWEB)

    Lessa, Tathiane C.R.F.; Mendes, Luis C.; Dias, Marcos L., E-mail: tathianecr@ima.ufrj.b [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Professora Eloisa Mano. Centro de Tecnologia

    2009-07-01

    The purpose of this study was to prepare oligomers from post-consumer PET with multifunctional alcohol, through melt processing, aiming to develop a new material, able to play a role as filler or property modifier. Maintaining constants the process conditions, content and kind of catalyst, the influence of the solvolysis agent on the PET depolymerization was investigated. The products were evaluated by wide-angle X-ray diffraction (WAXD) and thermogravimetry (TG/DTG). The changes in the WAXD curves and the shift of the maximum degradation temperature suggested that the ester linkages were broken being the ethylene glycol moieties replaced with hydroxyl-terminal groups of the multifunctional alcohol, as result of a transesterification reaction. The chemical structure of the new ester was named 'star-branching polymer'. (author)

  20. Analysis of glass and glass melts during the vitrification of fly and bottom ashes by laser-induced plasma spectroscopy. Part II. Process analysis

    Science.gov (United States)

    Panne, U.; Clara, M.; Haisch, C.; Niessner, R.

    1998-12-01

    Laser-induced plasma spectroscopy (LIPS) is employed for in situ and on-line process analysis of major glass constituents during a vitrification process for fly and bottom ashes from waste incineration. The system is based on an Nd:YAG laser for plasma ignition, while the elemental emissions from the plasma are detected time-resolved by an intensified multichannel analyzer. The perpendicular, single axis, imaging optics allow a remote sensing of the composition of the hot glass melt. Taking into account the plasma characteristics for calibration, good agreement between the LIPS analysis and the established reference analysis is achieved for the concentration ratios of SiO 2, Al 2O 3, and CaO. In addition, LIPS is applied to the analysis of aerosols generated by homogeneous nucleation during the heating-up of the investigated fly ashes. A distinctive temperature dependence of the heavy metal concentration of the aerosols is observed.

  1. Petrological Geodynamics of Mantle Melting I. AlphaMELTS + Multiphase Flow: Dynamic Equilibrium Melting, Method and Results

    Directory of Open Access Journals (Sweden)

    Massimiliano Tirone

    2017-10-01

    Full Text Available The complex process of melting in the Earth's interior is studied by combining a multiphase numerical flow model with the program AlphaMELTS which provides a petrological description based on thermodynamic principles. The objective is to address the fundamental question of the effect of the mantle and melt dynamics on the composition and abundance of the melt and the residual solid. The conceptual idea is based on a 1-D description of the melting process that develops along an ideal vertical column where local chemical equilibrium is assumed to apply at some level in space and time. By coupling together the transport model and the chemical thermodynamic model, the evolution of the melting process can be described in terms of melt distribution, temperature, pressure and solid and melt velocities but also variation of melt and residual solid composition and mineralogical abundance at any depth over time. In this first installment of a series of three contributions, a two-phase flow model (melt and solid assemblage is developed under the assumption of complete local equilibrium between melt and a peridotitic mantle (dynamic equilibrium melting, DEM. The solid mantle is also assumed to be completely dry. The present study addresses some but not all the potential factors affecting the melting process. The influence of permeability and viscosity of the solid matrix are considered in some detail. The essential features of the dynamic model and how it is interfaced with AlphaMELTS are clearly outlined. A detailed and explicit description of the numerical procedure should make this type of numerical models less obscure. The general observation that can be made from the outcome of several simulations carried out for this work is that the melt composition varies with depth, however the melt abundance not necessarily always increases moving upwards. When a quasi-steady state condition is achieved, that is when melt abundance does not varies significantly

  2. Estimation of the Temperature-Dependent Nitrogen Solubility in Stainless Fe-Cr-Mn-Ni-Si-C Steel Melts During Processing

    Science.gov (United States)

    Wendler, Marco; Hauser, Michael; Sandig, Eckhard Frank; Volkova, Olena

    2018-04-01

    The influence of chemical composition, temperature, and pressure on the nitrogen solubility of various high alloy stainless steel grades, namely Fe-14Cr-(0.17-7.77)Mn-6Ni-0.5Si-0.03C [wt pct], Fe-15Cr-3Mn-4Ni-0.5Si-0.1C [wt pct], and Fe-19Cr-3Mn-4Ni-0.5Si-0.15C [wt pct], was studied in the melt. The temperature-dependent N-solubility was determined using an empirical approach proposed by Wada and Pehlke. The thus calculated N-concentrations overestimate the actual N-solubility of all the studied Fe-Cr-Mn-Ni-Si-C steel melts at a given temperature and pressure. Consequently, the calculation model has to be modified by Si and C because both elements are not recognized in the original equation. The addition of the 1st and 2nd order interaction parameters for Si and C to the model by Wada and Pehlke allows a precise estimation of the temperature-dependent nitrogen solubility in the liquid steel bath, and fits very well with the measured nitrogen concentrations during processing of the steels. Moreover, the N-solubility enhancing effect of Cr- and Mn-additions has been demonstrated.

  3. Selective laser melting of an Al86Ni6Y4.5Co2La1.5 metallic glass: Processing, microstructure evolution and mechanical properties

    International Nuclear Information System (INIS)

    Li, X.P.; Kang, C.W.; Huang, H.; Zhang, L.C.; Sercombe, T.B.

    2014-01-01

    In this study, single line scans at different laser powers were carried out using selective laser meting (SLM) equipment on a pre-fabricated porous Al 86 Ni 6 Y 4.5 Co 2 La 1.5 metallic glass (MG) preform. The densification, microstructural evolution, phase transformation and mechanical properties of the scan tracks were systematically investigated. It was found that the morphology of the scan track was influenced by the energy distribution of the laser beam and the heat transfer competition between convection and conduction in the melt pool. Due to the Gaussian distribution of laser energy and heat transfer process, different regions of the scan track experienced different thermal histories, resulting in a gradient microstructure and mechanical properties. Higher laser powers caused higher thermal stresses, which led to the formation of cracks; while low power reduced the strength of the laser track, also inducing cracking. The thermal fluctuation at high laser power produced an inhomogeneous chemical distribution which gave rise to severe crystallization of the MG, despite the high cooling rate. The crystallization occurred both within the heat affected zone (HAZ) and at the edge of melt pool. However, by choosing an appropriate laser power crack-free scan tracks could be produced with no crystallization. This work provides the necessary fundamental understanding that will lead to the fabrication of large-size, crack-free MG with high density, controllable microstructure and mechanical properties using SLM

  4. Nitrogen Control in VIM Melts

    Science.gov (United States)

    Jablonski, P. D.; Hawk, J. A.

    NETL has developed a design and control philosophy for the addition of nitrogen to austenitic and ferritic steels. The design approach uses CALPHAD as the centerpiece to predict the level to which nitrogen is soluble in both the melt and the solid. Applications of this technique have revealed regions of "exclusion" in which the alloy, while within specification limits of prescribed, cannot be made by conventional melt processing. Furthermore, other investigations have found that substantial retrograde solubility of nitrogen exists, which can become problematic during subsequent melt processing and/or other finishing operations such as welding. Additionally, the CALPHAD method has been used to adjust primary melt conditions. To that end, nitrogen additions have been made using chrome nitride, silicon nitride, high-nitrogen ferrochrome as well as nitrogen gas. The advantages and disadvantages of each approach will be discussed and NETL experience in this area will be summarized with respect to steel structure.

  5. Design and Evaluation of Topical Diclofenac Sodium Gel Using Hot Melt Extrusion Technology as a Continuous Manufacturing Process with Kolliphor® P407.

    Science.gov (United States)

    Pawar, Jaywant; Narkhede, Rajkiran; Amin, Purnima; Tawde, Vaishali

    2017-08-01

    The aim of the present context was to develop and evaluate a Kolliphor® P407-based transdermal gel formulation of diclofenac sodium by hot melt extrusion (HME) technology; central composite design was used to optimize the formulation process. In this study, we have explored first time ever HME as an industrially feasible and continuous manufacturing technology for the manufacturing of gel formulation using Kolliphor® P407 and Kollisolv® PEG400 as a gel base. Diclofenac sodium was used as a model drug. The HME parameters such as feeding rate, screw speed, and barrel temperature were crucial for the semisolid product development, and were optimized after preliminary trials. For the processing of the gel formulation by HME, a modified screw design was used to obtain a uniform product. The obtained product was evaluated for physicochemical characterization such as differential scanning calorimetry (DSC), X-ray diffraction (XRD), pH measurement, rheology, surface tension, and texture profile analysis. Moreover, it was analyzed for general appearance, spreadibility, surface morphology, and drug content. The optimized gel formulation showed homogeneity and transparent film when applied on a glass slide under microscope, pH was 7.02 and uniform drug content of 100.04 ± 2.74 (SD = 3). The DSC and XRD analysis of the HME gel formulation showed complete melting of crystalline API into an amorphous form. The Kolliphor® P407 and Kollisolv® PEG400 formed excellent gel formulation using HME with consistent viscoelastic properties of the product. An improved drug release was found for the HME gel, which showed a 100% drug release than that of a marketed product which showed only 88% of drug release at the end of 12 h. The Flux value of the HME gel was 106 than that of a marketed formulation, which showed only about 60 value, inferring a significant difference (P < 0.05) at the end of 1 h. This study demonstrates a novel application of the hot melt extrusion

  6. Effect of Heat Treatment on Microstructure and Impact Toughness of Ti-6Al-4V Manufactured by Selective Laser Melting Process

    Directory of Open Access Journals (Sweden)

    Lee K.-A.

    2017-06-01

    Full Text Available This study manufactured Ti-6Al-4V alloy using one of the powder bed fusion 3D-printing processes, selective laser melting, and investigated the effect of heat treatment (650°C/3hrs on microstructure and impact toughness of the material. Initial microstructural observation identified prior-β grain along the building direction before and after heat treatment. In addition, the material formed a fully martensite structure before heat treatment, and after heat treatment, α and β phase were formed simultaneously. Charpy impact tests were conducted. The average impact energy measured as 6.0 J before heat treatment, and after heat treatment, the average impact energy increased by approximately 20% to 7.3 J. Fracture surface observation after the impact test showed that both alloys had brittle characteristics on macro levels, but showed ductile fracture characteristics and dimples at micro levels.

  7. Basal melt, seasonal water mass transformation, ocean current variability, and deep convection processes along the Amery Ice Shelf calving front, East Antarctica}

    Science.gov (United States)

    Herraiz Borreguero, Laura; Church, John A.; Alison, Ian; Peña Molino, Beatriz; Coleman, Richard; Tomczak, Mathias; Craven, Mike

    2017-04-01

    Despite the Amery Ice Shelf (AIS) being the third largest ice shelf in Antarctica, the seasonal variability of the physical processes involved in the AIS-ocean interaction remains undocumented and a robust observational, oceanographic-based basal melt rate estimate has been lacking. Here we use year-long time series of water column temperature, salinity, and horizontal velocities measured along the ice shelf front from 2001 to 2002. Our results show strong zonal variations in the distribution of water masses along the ice shelf front: modified Circumpolar Deep Water (mCDW) arrives in the east, while in the west, Ice Shelf Water (ISW) and Dense Shelf Water (DSW) formed in the Mackenzie polynya dominate the water column. Baroclinic eddies, formed during winter deep convection (down to 1100 m), drive the inflow of DSW into the ice shelf cavity. Our net basal melt rate estimate is 57.4±25.3 Gt yr?1 (1±0.4 m yr?1), larger than previous modeling-based and glaciological-based estimates, and results from the inflow of DSW (0.52±0.38 Sv; 1 Sv=106 m3 s?1) and mCDW (0.22±0.06 Sv) into the cavity. Our results highlight the role of the Mackenzie polynya in the seasonal exchange of water masses across the ice shelf front, and the role of the ISW in controlling the formation rate and thermohaline properties of DSW. These two processes directly impact on the ice shelf mass balance, and on the contribution of DSW/ISW to the formation of Antarctic Bottom Water.

  8. Melt processing of poly(L‐lactic acid) in the presence of organomodified anionic or cationic clays

    DEFF Research Database (Denmark)

    Katiyar, Vimal; Gerds, Nathalie; Koch, Christian Bender

    2011-01-01

    . Although this reduction in molecular weight was still very significant, it was less when a PLA/LDH‐C12 masterbatch was processed. In contrast, there was no significant reduction in PLA molecular weight when processing with Cloisite® 30B. However, film transparency was compromised when either LDH or MMT...

  9. Oxidation-reduction processes upon interaction of aluminum oxide melt with molybdenum and tungsten in a hydrogen-containing atmosphere

    Science.gov (United States)

    Kostomarov, D. V.

    2017-07-01

    A thermodynamic analysis of the processes occurring in the Mo-W-Al2O3 system at T = 2400 K and a total pressure of 1 bar, set by controlled reducing Ar + H2 atmosphere, has been performed. It is found that the basic components of the system do not interact directly, although may be actively involved in chemical reactions with participation of other components to undergo numerous cyclic oxidation-reduction processes. Particular attention is paid to the processes involving such chemically active reagents as H2O2, HO2, H2 (H), gaseous Al, and its hydrides (AlH, AlH2, AlH3).

  10. Dimensional accuracy of internal cooling channel made by selective laser melting (SLM And direct metal laser sintering (DMLS processes in fabrication of internally cooled cutting tools

    Directory of Open Access Journals (Sweden)

    Ghani S. A. C.

    2017-01-01

    Full Text Available Selective laser melting(SLM and direct metal laser sintering(DMLS are preferred additive manufacturing processes in producing complex physical products directly from CAD computer data, nowadays. The advancement of additive manufacturing promotes the design of internally cooled cutting tool for effectively used in removing generated heat in metal machining. Despite the utilisation of SLM and DMLS in a fabrication of internally cooled cutting tool, the level of accuracy of the parts produced remains uncertain. This paper aims at comparing the dimensional accuracy of SLM and DMLS in machining internally cooled cutting tool with a special focus on geometrical dimensions such as hole diameter. The surface roughness produced by the two processes are measured with contact perthometer. To achieve the objectives, geometrical dimensions of identical tool holders for internally cooled cutting tools fabricated by SLM and DMLS have been determined by using digital vernier calliper and various magnification of a portable microscope. In the current study, comparing internally cooled cutting tools made of SLM and DMLS showed that generally the higher degree of accuracy could be obtained with DMLS process. However, the observed differences in surface roughness between SLM and DMLS in this study were not significant. The most obvious finding to emerge from this study is that the additive manufacturing processes selected for fabricating the tool holders for internally cooled cutting tool in this research are capable of producing the desired internal channel shape of internally cooled cutting tool.

  11. Phase interaction in the metal-oxide melts-gas system the modeling of structure, properties and processes

    CERN Document Server

    Boronenkov, V; Leontiev, L

    2012-01-01

    This monograph describes mathematical models that enable prediction of phase compositions for various technological processes, as developed on the base of a complex physico-chemical analysis of reaction. It studies thermodynamics and kinetics of specific stages of complex pyrometallurgical processes involving boron, carbon, sulfur, tungsten, phosphorus, and many more, as well as their exposure to all sorts of factors. First and foremost, this enables to optimize processes and technologies at the stage of design, while traditional empirical means of development of new technologies are basically incapable of providing an optimal solution. Simulation results of metals and alloys production, welding and coating technologies allow obtaining materials with pre-given composition, structure and properties in a cost-saving and conscious manner. Moreover, a so-called "inverse problem", i.e., selecting source materials which would ensure the required results, cannot be solved by any other means.

  12. Control of Y-211 content in bulk YBCO superconductors fabricated by a buffer-aided, top seeded infiltration and growth melt process

    International Nuclear Information System (INIS)

    Namburi, Devendra K; Shi, Yunhua; Palmer, Kysen G; Dennis, Anthony R; Durrell, John H; Cardwell, David A

    2016-01-01

    Bulk (RE)–Ba–Cu–O ((RE)BCO, where RE stands for rare-earth), single grain superconductors can trap magnetic fields of several tesla at low temperatures and therefore can function potentially as high field magnets. Although top seeded melt growth (TSMG) is an established process for fabricating relatively high quality single grains of (RE)BCO for high field applications, this technique suffers from inherent problems such as sample shrinkage, a large intrinsic porosity and the presence of (RE) 2 BaCuO 5 (RE-211)-free regions in the single grain microstructure. Seeded infiltration and growth (SIG), therefore, has emerged as a practical alternative to TSMG that overcomes many of these problems. Until now, however, the superconducting properties of bulk materials processed by SIG have been inferior to those fabricated using the TSMG technique. In this study, we identify that the inferior properties of SIG processed bulk superconductors are related to the presence of a relatively large Y-211 content (∼41.8%) in the single grain microstructure. Controlling the RE-211 content in SIG bulk samples is particularly challenging because it is difficult to regulate the entry of the liquid phase into the solid RE-211 preform during the infiltration process. In an attempt to solve this issue, we have investigated the effect of careful control of both the infiltration temperature and the quantity of liquid phase powder present in the sample preforms prior to processing. We conclude that careful control of the infiltration temperature is the most promising of these two process variables. Using this knowledge, we have fabricated successfully a YBCO bulk single grain using the SIG process of diameter 25 mm that exhibits a trapped field of 0.69 T at 77 K, which is the largest value reported to date for a sample fabricated by the SIG technique. (paper)

  13. A low-cost batch process for high-performance melt-textured GdBaCuO pellets

    Czech Academy of Sciences Publication Activity Database

    Muralidhar, M.; Tomita, M.; Suzuki, K.; Jirsa, Miloš; Fukumoto, .Y.; Ishihara, A.

    2010-01-01

    Roč. 23, č. 4 (2010), 045033/1-045033/7 ISSN 0953-2048 Institutional research plan: CEZ:AV0Z10100520 Keywords : superconducting magnet * GdBaCuO * batch process * high-Tc bulk Subject RIV: BM - Solid Matter Physics ; Magnet ism Impact factor: 2.402, year: 2010

  14. Low-complexity full-melt laser-anneal process for fabrication of low-leakage implanted ultrashallow junctions

    NARCIS (Netherlands)

    Biasotto, C.; Gonda, V.; Nanver, L.K.; Scholtes, T.L.M.; Van der Cingel, J.; Vidal, D.; Jovanovic, V.

    2011-01-01

    Good-quality ultrashallow n + p junctions are formed using 5-keV amorphizing As+ implantations followed by a single-shot excimer laser anneal for dopant activation. By using an implant that is self-aligned to the contact windows etched in an oxide isolation layer, straightforward processing of the

  15. Investigating the links between the process parameters and their influence on the aesthetic evaluation of selective laser melted parts

    NARCIS (Netherlands)

    Galimberti, G.; Doubrovski, E.L.; Guagliano, M.; Previtali, B.; Verlinden, J.C.; Bourell, David L.; Crawford, Richard H.; Seepersad, Carolyn C.; Beaman, Joseph J.; Fish, Scott; Marcus, Harris

    2016-01-01

    This study is a precursor to gaining a deeper understanding of how each parameter of the Additive Manufacturing (AM) process influences the aesthetic properties of 3D printed products. Little research has been conducted on this specific aspect of AM. Using insights from the work presented in this

  16. New Development in Selective Laser Melting of Ti-6Al-4V: A Wider Processing Window for the Achievement of Fully Lamellar α + β Microstructures

    Science.gov (United States)

    Lui, E. W.; Xu, W.; Pateras, A.; Qian, M.; Brandt, M.

    2017-12-01

    Recent progress has shown that Ti-6Al-4V fabricated by selective laser melting (SLM) can achieve a fully lamellar α + β microstructure using 60 µm layer thickness in the as-built state via in situ martensite decomposition by manipulating the processing parameters. The potential to broaden the processing window was explored in this study by increasing the layer thickness to the less commonly used 90 µm. Fully lamellar α + β microstructures were produced in the as-built state using inter-layer times in the range of 1-12 s. Microstructural features such as the α-lath thickness and morphology were sensitive to both build height and inter-layer time. The α-laths produced using the inter-layer time of 1 s were much coarser than those produced with the inter-layer time of 12 s. The fine fully lamellar α + β structure resulted in tensile ductility of 11% and yield strength of 980 MPa. The tensile properties can be further improved by minimizing the presence of process-induced defects.

  17. Scaleable Clean Aluminum Melting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Han, Q.; Das, S.K. (Secat, Inc.)

    2008-02-15

    The project entitled 'Scaleable Clean Aluminum Melting Systems' was a Cooperative Research and Development Agreements (CRADAs) between Oak Ridge National Laboratory (ORNL) and Secat Inc. The three-year project was initially funded for the first year and was then canceled due to funding cuts at the DOE headquarters. The limited funds allowed the research team to visit industrial sites and investigate the status of using immersion heaters for aluminum melting applications. Primary concepts were proposed on the design of furnaces using immersion heaters for melting. The proposed project can continue if the funding agency resumes the funds to this research. The objective of this project was to develop and demonstrate integrated, retrofitable technologies for clean melting systems for aluminum in both the Metal Casting and integrated aluminum processing industries. The scope focused on immersion heating coupled with metal circulation systems that provide significant opportunity for energy savings as well as reduction of melt loss in the form of dross. The project aimed at the development and integration of technologies that would enable significant reduction in the energy consumption and environmental impacts of melting aluminum through substitution of immersion heating for the conventional radiant burner methods used in reverberatory furnaces. Specifically, the program would couple heater improvements with furnace modeling that would enable cost-effective retrofits to a range of existing furnace sizes, reducing the economic barrier to application.

  18. Retrieving original melt compositions in migmatites

    Science.gov (United States)

    Kriegsman, L. M.; Nyström, A. I.

    2003-04-01

    The final textures and mineral modes of anatectic migmatites are affected by four successive processes: (i) prograde partial melting and small-scale segregation into melt-rich domains and restitic domains; (ii) partial melt extraction; (iii) partial retrograde reactions (back reaction) between in situ crystallizing melt and the restite; (iv) crystallization of remaining melt at the water-saturated solidus, releasing volatiles (Kriegsman, 2001). These processes are investigated using mass balance calculations in the KFMASH chemical system. Starting from a fixed bulk composition, fluid-absent melting reactions are considered along an isobaric heating path, followed by mineral-melt reactions during isobaric cooling (path 1), and uplift (path 2). Variables in the model are the restite fraction X and the melt fraction Y involved in back reaction, the melt fraction Z extracted from the system, and the melt fraction 1-Y-Z crystallized in situ at the water-saturated solidus. Incongruent phases are considered to be part of the restite. To facilitate calculations, mineral and melt compositions are taken to be constant. It is shown that melanosome, leucosome, and mesosome compositions generally do not show linear compositional trends in a closed system. Instead, mesosome, neosome, protolith and melt compositions lie on a hyperplane and form linear trends in any compositional diagram. Several methods are proposed to retrieve the melt composition from neosome and mesosome compositions. Applications to natural examples (dataset of Ashworth, 1976; and our new data from SW Finland) strengthen the migmatite-to-granite connection which may notably be obscured by the back reaction process. References: Kriegsman, L.M., 2001, Lithos 56, 75-96 Ashworth, J.R., 1976. Mineralogical Magazine 40, 661-682

  19. Water, lithium and trace element compositions of olivine from Lanzo South replacive mantle dunites (Western Alps): New constraints into melt migration processes at cold thermal regimes

    Science.gov (United States)

    Sanfilippo, Alessio; Tribuzio, Riccardo; Ottolini, Luisa; Hamada, Morihisa

    2017-10-01

    Replacive mantle dunites are considered to be shallow pathways for extraction of mantle melts from their source region. Dunites offer a unique possibility to unravel the compositional variability of the melts produced in the upper mantle, before mixing and crystal fractionation modify their original signature. This study includes a quantification of H2O, Li and trace elements (Ni, Mn, Co, Sc, V, Ti, Zr, Y and HREE) in olivine from large replacive dunite bodies (>20 m) within a mantle section exposed in the Western Italian Alps (Lanzo South ophiolite). On the basis of olivine, clinopyroxene and spinel compositions, these dunites were previously interpreted to be formed by melts with a MORB signature. Variations in Ni, Mn, Co and Ca contents in olivine from different dunite bodies suggested formation by different melt batches. The variable H2O and Li contents of these olivines agree with this idea. Compared to olivine from residual peridotites and olivine phenocrysts in MORB (both having H2O 1 ppm), the Lanzo South dunite olivine has high H2O (18-40 ppm) and low Li (0.35-0.83 ppm) contents. Geochemical modelling suggests that the dunite-forming melts were produced by low melting degrees of a mixed garnet-pyroxenite-peridotite mantle source, with a contribution of a garnet pyroxenite component variable from 20 to 80%. The Lanzo dunites experienced migration of melts geochemically enriched and mainly produced in the lowermost part of the melting region. Extraction of enriched melts through dunite channels are probably characteristic of cold thermal regimes, where low temperatures and a thick mantle lithosphere inhibit mixing with melts produced at shallower depths.

  20. Raman spectroscopy for the in-line polymer-drug quantification and solid state characterization during a pharmaceutical hot-melt extrusion process.

    Science.gov (United States)

    Saerens, L; Dierickx, L; Lenain, B; Vervaet, C; Remon, J P; De Beer, T

    2011-01-01

    The aim of this study was to evaluate the suitability of Raman spectroscopy as a Process Analytical Technology (PAT) tool for the in-line determination of the active pharmaceutical ingredient (API) concentration and the polymer-drug solid state during a pharmaceutical hot-melt extrusion process. For in-line API quantification, different metoprolol tartrate (MPT)--Eudragit® RL PO mixtures, containing 10%, 20%, 30% and 40% MPT, respectively, were extruded and monitored in-line in the die using Raman spectroscopy. A PLS model, regressing the MPT concentrations versus the in-line collected Raman spectra, was developed and validated, allowing real-time API concentration determination. The correlation between the predicted and real MPT concentrations of the validation samples is acceptable (R(2)=0.997). The predictive performance of the calibration model is rated by the root mean square error of prediction (RMSEP), which is 0.59%. Two different polymer-drug mixtures were prepared to evaluate the suitability of Raman spectroscopy for in-line polymer-drug solid state characterization. Mixture 1 contained 90% Eudragit® RS PO and 10% MPT and was extruded at 140°C, hence producing a solid solution. Mixture 2 contained 60% Eudragit® RS PO and 40% MPT and was extruded at 105°C, producing a solid dispersion. The Raman spectra collected during these extrusion processes provided two main observations. First, the MPT Raman peaks in the solid solution broadened compared to the corresponding solid dispersion peaks, indicating the presence of amorphous MPT. Second, peak shifts appeared in the spectra of the solid dispersion and solid solution compared to the physical mixtures, suggesting interactions between Eudragit® RS PO and MPT, most likely hydrogen bonds. These shifts were larger in the spectra of the solid solution. DSC analysis confirmed these Raman solid state observations and the interactions seen in the spectra. Raman spectroscopy is a potential PAT-tool for in

  1. Hanford Waste Vitrification Program process development: Melt testing subtask, pilot-scale ceramic melter experiment, run summary

    International Nuclear Information System (INIS)

    Nakaoka, R.K.; Bates, S.O.; Elmore, M.R.; Goles, R.W.; Perez, J.M.; Scott, P.A.; Westsik, J.H.

    1996-03-01

    Hanford Waste Vitrification Program (HWVP) activities for FY 1985 have included engineering and pilot-scale melter experiments HWVP-11/HBCM-85-1 and HWVP-12/PSCM-22. Major objectives designated by HWVP fo these tests were to evaluate the processing characteristics of the current HWVP melter feed during actual melter operation and establish the product quality of HW-39 borosilicate glass. The current melter feed, defined during FY 85, consists of reference feed (HWVP-RF) and glass-forming chemicals added as frit

  2. Hanford Waste Vitrification Program process development: Melt testing subtask, pilot-scale ceramic melter experiment, run summary

    Energy Technology Data Exchange (ETDEWEB)

    Nakaoka, R.K.; Bates, S.O.; Elmore, M.R.; Goles, R.W.; Perez, J.M.; Scott, P.A.; Westsik, J.H.

    1996-03-01

    Hanford Waste Vitrification Program (HWVP) activities for FY 1985 have included engineering and pilot-scale melter experiments HWVP-11/HBCM-85-1 and HWVP-12/PSCM-22. Major objectives designated by HWVP fo these tests were to evaluate the processing characteristics of the current HWVP melter feed during actual melter operation and establish the product quality of HW-39 borosilicate glass. The current melter feed, defined during FY 85, consists of reference feed (HWVP-RF) and glass-forming chemicals added as frit.

  3. Effects of process parameters on properties of porous foams formed by laser-assisted melting of steel powder (AISI P21)/foaming agent (ZrH2) mixture

    Science.gov (United States)

    Seo, Ja-Ye; Lee, Ki-Yong; Shim, Do-Sik

    2018-01-01

    This paper describes the fabrication of lightweight metal foams using the directed energy deposition (DED) method. DED is a highly flexible additive manufacturing process wherein a metal powder mixed with a foaming agent is sprayed while a high-power laser is used to simultaneously melt the powder mixture into layered metal foams. In this study, a mixture of a carbon steel material (P21 powder) and a widely used foaming agent, ZrH2, is used to fabricate metal foams. The effects of various process parameters, such as the laser power, powder feed rate, powder gas flow rate, and scanning speed, on the deposition characteristics (porosity, pore size, and pore distribution) are investigated. The synthesized metal foams exhibit porosities of 10% or lower, and a mean pore area of 7 × 105 μm2. It is observed that the degree of foaming increases in proportion to the laser power to a certain extent. The results also show that the powder feed rate has the most pronounced effect on the porosity of the metal foams, while the powder gas flow rate is the most suitable parameter for adjusting the size of the pores formed within the foams. Further, the scanning speed, which determines the amounts of energy and powder delivered, has a significant effect on the height of the deposits as well as on the properties of the foams. Thus, during the DED process for fabricating metal foams, the pore size and distribution and hence the foam porosity can be tailored by varying the individual process parameters. These findings should be useful as reference data for the design of processes for fabricating porous metallic materials that meet the specific requirements for specialized parts.

  4. Integrated hot-melt extrusion - injection molding continuous tablet manufacturing platform: Effects of critical process parameters and formulation attributes on product robustness and dimensional stability.

    Science.gov (United States)

    Desai, Parind M; Hogan, Rachael C; Brancazio, David; Puri, Vibha; Jensen, Keith D; Chun, Jung-Hoon; Myerson, Allan S; Trout, Bernhardt L

    2017-10-05

    This study provides a framework for robust tablet development using an integrated hot-melt extrusion-injection molding (IM) continuous manufacturing platform. Griseofulvin, maltodextrin, xylitol and lactose were employed as drug, carrier, plasticizer and reinforcing agent respectively. A pre-blended drug-excipient mixture was fed from a loss-in-weight feeder to a twin-screw extruder. The extrudate was subsequently injected directly into the integrated IM unit and molded into tablets. Tablets were stored in different storage conditions up to 20 weeks to monitor physical stability and were evaluated by polarized light microscopy, DSC, SEM, XRD and dissolution analysis. Optimized injection pressure provided robust tablet formulations. Tablets manufactured at low and high injection pressures exhibited the flaws of sink marks and flashing respectively. Higher solidification temperature during IM process reduced the thermal induced residual stress and prevented chipping and cracking issues. Polarized light microscopy revealed a homogeneous dispersion of crystalline griseofulvin in an amorphous matrix. DSC underpinned the effect of high tablet residual moisture on maltodextrin-xylitol phase separation that resulted in dimensional instability. Tablets with low residual moisture demonstrated long term dimensional stability. This study serves as a model for IM tablet formulations for mechanistic understanding of critical process parameters and formulation attributes required for optimal product performance. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Interaction processes between vacancies and dislocations in molybdenum in the temperature range around 0.3 of the melting temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zelada-Lambri, G.I. [Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Laboratorio de Materiales, Escuela de Ingenieria Electrica, Avenida Pellegrini 250, 2000 Rosario (Argentina); Lambri, O.A. [Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Laboratorio de Materiales, Escuela de Ingenieria Electrica, Avenida Pellegrini 250, 2000 Rosario (Argentina); Instituto de Fisica Rosario, Member of the CONICET' s Research Staff (Argentina)], E-mail: olambri@fceia.unr.edu.ar; Bozzano, P.B. [Laboratorio de Microscopia Electronica, Unidad de Actividad Materiales, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Avenida General Paz 1499, 1650 San Martin (Argentina); Garcia, J.A. [Departamento de Fisica Aplicada II, Facultad de Ciencias y Tecnologia, Universidad del Pais Vasco, Apartado 644, 48080 Bilbao, Pais Vasco (Spain); Celauro, C.A. [Reactor Nuclear RA-4, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Riobamba y Berruti, 2000 Rosario (Argentina)

    2008-10-15

    Mechanical spectroscopy, electrical resistivity and transmission electron microscopy studies have been performed on pre-strained neutron irradiated single crystalline molybdenum in order to check the interaction processes between vacancies and dislocations in the temperature range between room temperature and 1273 K. The anelastic relaxation in molybdenum which appears between 800 K and 1273 K has been separated in two different physical mechanisms depending on the temperature of appearance of the relaxation peak. The physical mechanism which controls the damping peak appearing at around 800 K was related with the dragging of jogs by the dislocation under movement assisted by vacancy diffusion. The damping peak which appears at higher temperatures of about 1000 K was more consistent with the formation and diffusion of vacancies assisted by the dislocation movement.

  6. Characteristics of Optical Diffusers for Light-Emitting Diodes Backlight Unit Prepared by Melt-Extrusion Process

    Science.gov (United States)

    Kim, Hyo Jin; Kim, Dong Won; Kim, Seong Woo

    2013-10-01

    Using extrusion compounding followed by compression molding processes, polycarbonate-based optical diffusers with uniform dispersion of diffusing particles could be prepared for application in direct-lit LED backlight unit. Inorganic porous silica and organic silicone microsphere particles were employed as diffusing agents. The inclusion of diffusing particles up to 3 wt % substantially improved the luminance uniformity with respect to both location and viewing angle, and the effect was shown to be more prominent for the silicone particles. Alternatively, inorganic silica particles could yield diffusers with enhanced absolute luminance and thermal resistance property. The thermo-mechanical property of the elastic modulus was revealed to be improved upon addition of diffusing particles of silica and silicone with cross-linked structure.

  7. Direct writing by way of melt electrospinning.

    Science.gov (United States)

    Brown, Toby D; Dalton, Paul D; Hutmacher, Dietmar W

    2011-12-15

    Melt electrospun fibers of poly(ϵ-caprolactone) are accurately deposited using an automated stage as the collector. Matching the translation speed of the collector to the speed of the melt electrospinning jet establishes control over the location of fiber deposition. In this sense, melt electrospinning writing can be seen to bridge the gap between solution electrospinning and direct writing additive manufacturing processes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Impact-melt origin for the Simondium, Pinnaroo, and Hainholz mesosiderites: implicatiions for impact processes beyond the Earth--Moon system

    International Nuclear Information System (INIS)

    Floran, R.J.; Caulfield, J.B.D.; Harlow, G.E.; Prinz, M.

    1978-05-01

    The Simondium, Pinnaroo, and Hainholz mesosiderites are interpreted to be clast-laden impact melts that crystallized from immiscible silicate, metallic (Fe-FeS) liquids. The existence of silicate melts is shown by intergranular basaltic textures. Metallic melts are inferred on the basis of smooth boundaries between metal and troilite and the occurrence of troilite as anastomosing areas that radiate outward into the silicate fractions. These relations suggest that troilite crystallized after silicates, concentrating as a late-stage residuum. Evidence for impact melting includes: diversity and abundance of clast types (mineral, metal, lithic) in various stages of recrystallization and assimilation; differences in mineral chemistries between clasts and igneous-textured matrix silicates; unusual metal plus silicate bulk composition. Silicate clasts consist primarily of orthopyroxene and minor olivine with a range of Fe/Fe + Mg ratios, anorthitic plagioclase, and rare orthopyroxenite (diogenite) fragments. Substantial amounts of Fe-Ni metal were melted during the impact events and minor amounts were incorporated into the melts as clasts. The clast populations suggest that at least four rock types were melted and mixed: (a) diogenite, (b) a plagioclase-rich source, possibly cumulate eucrite, (c) dunite, and (d) metal. Most orthopyroxene appears to have been derived from fragmentation of diogenites. Orthopyroxene (En/sub 82-61/) and olivine (Fo/sub 86-67/) clasts include much material unsampled as individual meteorites and probably represent a variety of source rocks

  9. Melting under shock compression

    International Nuclear Information System (INIS)

    Bennett, B.I.

    1980-10-01

    A simple model, using experimentally measured shock and particle velocities, is applied to the Lindemann melting formula to predict the density, temperature, and pressure at which a material will melt when shocked from room temperature and zero pressure initial conditions

  10. Use of fine-grained shredder dust as a cement admixture after a melting, rapid-cooling and pulverizing process

    International Nuclear Information System (INIS)

    Kakimoto, Kohji; Nakano, Yasuko; Yamasaki, Takehiro; Shimizu, Keisuke; Idemitsu, Takashi

    2004-01-01

    Shredder dust is a residue, which is removed from valuable ferrous metals found in scrap automobile and electronic waste. It is also an industrial waste byproduct which, under legislation in place since April 1996, must be disposed of in landfill sites. One method of disposing shredder dust is by scorification, however, this is a costly process and therefore impractical. Costs could be reduced if the shredder dust had a valuable use, and, in this paper, the authors examine its effectiveness as a cement admixture. First, molten shredder dust was crushed for use as a cement admixture. However, it was difficult to crush it completely because metallic grains were mixed in with molten shredder dust. These particles were removed by sifting and the molten shredder dust was crushed once again. Eventually, a fine 75 μm and less powder type of slag was obtained. This slag was mixed with Ordinary Portland Cement (OPC) to form a cement mortar and subsequently a mortar test was conducted. From the test results, it was found that the long-term strength of the cement did not deteriorate even when it included 30% by weight of the pulverized molten shredder dust

  11. Migration of additive molecules in a polymer filament obtained by melt spinning: Influence of the fiber processing steps

    Science.gov (United States)

    Gesta, E.; Skovmand, O.; Espuche, E.; Fulchiron, R.

    2015-12-01

    The purpose of this study is to understand the influence of the yarn processing on the migration of additives molecules, especially insecticide, within polyethylene (PE) yarns. Yarns were manufactured in the laboratory focusing on three key-steps (spinning, post-stretching and heat-setting). Influence of each step on yarn properties was investigated using tensile tests, differential scanning calorimetry and wide-angle X-ray diffraction. The post-stretching step was proved to be critical in defining yarn mechanical and structural properties. Although a first orientation of polyethylene crystals was induced during spinning, the optimal orientation was only reached by post-stretching. The results also showed that the heat-setting did not significantly change these properties. The presence of additives crystals at the yarn surface was evidenced by scanning-electron microscopy. These studies performed at each yarn production step allowed a detailed analysis of the additives' ability to migrate. It is concluded that while post-stretching decreased the migration rate, heat-setting seems to boost this migration.

  12. Migration of additive molecules in a polymer filament obtained by melt spinning: Influence of the fiber processing steps

    Energy Technology Data Exchange (ETDEWEB)

    Gesta, E. [Ingénierie des Matériaux Polymères - UMR CNRS 5223, Université de Lyon - Université Lyon 1, Bâtiment POLYTECH Lyon - 15 boulevard Latarjet, 69622, Villeurbanne (France); Intelligent Insect Control, 118 Chemin des Alouettes, Castelnau-le-Lez, 34170 (France); Skovmand, O., E-mail: osk@insectcontrol.net [Intelligent Insect Control, 118 Chemin des Alouettes, Castelnau-le-Lez, 34170 (France); Espuche, E., E-mail: eliane.espuche@univ-lyon1.fr; Fulchiron, R., E-mail: rene.fulchiron@univ-lyon1.fr [Ingénierie des Matériaux Polymères - UMR CNRS 5223, Université de Lyon - Université Lyon 1, Bâtiment POLYTECH Lyon - 15 boulevard Latarjet, 69622, Villeurbanne (France)

    2015-12-17

    The purpose of this study is to understand the influence of the yarn processing on the migration of additives molecules, especially insecticide, within polyethylene (PE) yarns. Yarns were manufactured in the laboratory focusing on three key-steps (spinning, post-stretching and heat-setting). Influence of each step on yarn properties was investigated using tensile tests, differential scanning calorimetry and wide-angle X-ray diffraction. The post-stretching step was proved to be critical in defining yarn mechanical and structural properties. Although a first orientation of polyethylene crystals was induced during spinning, the optimal orientation was only reached by post-stretching. The results also showed that the heat-setting did not significantly change these properties. The presence of additives crystals at the yarn surface was evidenced by scanning-electron microscopy. These studies performed at each yarn production step allowed a detailed analysis of the additives’ ability to migrate. It is concluded that while post-stretching decreased the migration rate, heat-setting seems to boost this migration.

  13. Migration of additive molecules in a polymer filament obtained by melt spinning: Influence of the fiber processing steps

    International Nuclear Information System (INIS)

    Gesta, E.; Skovmand, O.; Espuche, E.; Fulchiron, R.

    2015-01-01

    The purpose of this study is to understand the influence of the yarn processing on the migration of additives molecules, especially insecticide, within polyethylene (PE) yarns. Yarns were manufactured in the laboratory focusing on three key-steps (spinning, post-stretching and heat-setting). Influence of each step on yarn properties was investigated using tensile tests, differential scanning calorimetry and wide-angle X-ray diffraction. The post-stretching step was proved to be critical in defining yarn mechanical and structural properties. Although a first orientation of polyethylene crystals was induced during spinning, the optimal orientation was only reached by post-stretching. The results also showed that the heat-setting did not significantly change these properties. The presence of additives crystals at the yarn surface was evidenced by scanning-electron microscopy. These studies performed at each yarn production step allowed a detailed analysis of the additives’ ability to migrate. It is concluded that while post-stretching decreased the migration rate, heat-setting seems to boost this migration

  14. Use of fine-grained shredder dust as a cement admixture after a melting, rapid-cooling and pulverizing process

    Energy Technology Data Exchange (ETDEWEB)

    Kakimoto, K. [Kyushu Institute of Technology, Fukuoka (Japan). Department of Applied Chemistry; Nakano, Y. [Kyushu Institute of Technology, Fukuoka (Japan). Graduate School, Department of Engineering; Yamasaki, T.; Shimuzu, K.; Idemitsu, T. [Kyushu Institute of Technology, Fukyoka (Japan). Department of Civil Engineering

    2004-12-01

    Shredder dust is a residue, which is removed from valuable ferrous metals found in scrap automobile and electronic waste. It is also an industrial waste byproduct which, under legislation in place since April 1996, must be disposed of in landfill sites. One method of disposing shredder dust is by scorification, however, this is a costly process and therefore impractical. Costs could be reduced if the shredder dust had a valuable use, and, in this paper, the authors examine its effectiveness as a cement admixture. First, molten shredder dust was crushed for use as a cement admixture. However, it was difficult to crush it completely because metallic grains were mixed in with molten shredder dust. These particles were removed by sifting and the molten shredder dust was crushed once again. Eventually, a fine 75 {mu}m and less powder type of slag was obtained. This slag was mixed with Ordinary Portland Cement (OPC) to form a cement mortar and subsequently a mortar test was conducted. From the test results, it was found that the long-term strength of the cement did not deteriorate even when it included 30% by weight of the pulverized molten shredder dust. (author)

  15. Melt Rate Improvement for DWPF MB3: Melt Rate Furnace Testing

    Energy Technology Data Exchange (ETDEWEB)

    Stone, M.E.

    2001-07-24

    The Defense Waste Processing Facility (DWPF) would like to increase its canister production rate. The goal of this study is to improve the melt rate in DWPF specifically for Macrobatch 3. However, the knowledge gained may result in improved melting efficiencies translating to future DWPF macrobatches and in higher throughput for other Department of Energy's (DOE) melters. Increased melting efficiencies decrease overall operational costs by reducing the immobilization campaign time for a particular waste stream. For melt rate limited systems, a small increase in melting efficiency translates into significant hard dollar savings by reducing life cycle operational costs.

  16. Effect of Energy Input on Microstructure and Mechanical Properties of Titanium Aluminide Alloy Fabricated by the Additive Manufacturing Process of Electron Beam Melting

    Directory of Open Access Journals (Sweden)

    Ashfaq Mohammad

    2017-02-01

    Full Text Available Titanium aluminides qualify adequately for advanced aero-engine applications in place of conventional nickel based superalloys. The combination of high temperature properties and lower density gives an edge to the titanium aluminide alloys. Nevertheless, challenges remain on how to process these essentially intermetallic alloys in to an actual product. Electron Beam Melting (EBM, an Additive Manufacturing Method, can build complex shaped solid parts from a given feedstock powder, thus overcoming the shortcomings of the conventional processing techniques such as machining and forging. The amount of energy supplied by the electron beam has considerable influence on the final build quality in the EBM process. Energy input is decided by the beam voltage, beam scan speed, beam current, and track offset distance. In the current work, beam current and track offset were varied to reflect three levels of energy input. Microstructural and mechanical properties were evaluated for these samples. The microstructure gradually coarsened from top to bottom along the build direction. Whereas higher energy favored lath microstructure, lower energy tended toward equiaxed grains. Computed tomography analysis revealed a greater amount of porosity in low energy samples. In addition, the lack of bonding defects led to premature failure in the tension test of low energy samples. Increase in energy to a medium level largely cancelled out the porosity, thereby increasing the strength. However, this trend did not continue with the high energy samples. Electron microscopy and X-ray diffraction investigations were carried out to understand this non-linear behavior of the strength in the three samples. Overall, the results of this work suggest that the input energy should be considered primarily whenever any new alloy system has to be processed through the EBM route.

  17. [Solder melting torches].

    Science.gov (United States)

    Cubero Postigo, G

    1988-11-01

    In this study about melting and torchs employed in solder in fixed prosthodontics, it's analysed the accurate melting, adequate quantity, as well as protection of adjacent tissues with an accurate anti-melting. The torch chosen is the oxyacetylene burner, because its greater calorific power.

  18. Interplay between cellular activity and three-dimensional scaffold-cell constructs with different foam structure processed by electron beam melting.

    Science.gov (United States)

    Nune, Krishna C; Misra, R Devesh K; Gaytan, Sara M; Murr, Lawrence E

    2015-05-01

    The cellular activity, biological response, and consequent integration of scaffold-cell construct in the physiological system are governed by the ability of cells to adhere, proliferate, and biomineralize. In this regard, we combine cellular biology and materials science and engineering to fundamentally elucidate the interplay between cellular activity and interconnected three-dimensional foamed architecture obtained by a novel process of electron beam melting and computational tools. Furthermore, the organization of key proteins, notably, actin, vinclulin, and fibronectin, involved in cellular activity and biological functions and relationship with the structure was explored. The interconnected foamed structure with ligaments was favorable to cellular activity that includes cell attachment, proliferation, and differentiation. The primary rationale for favorable modulation of cellular functions is that the foamed structure provided a channel for migration and communication between cells leading to highly mineralized extracellular matrix (ECM) by the differentiating osteoblasts. The filopodial interaction amongst cells on the ligaments was a governing factor in the secretion of ECM, with consequent influence on maturation and mineralization. © 2014 Wiley Periodicals, Inc.

  19. Single Phase Melt Processed Powellite (Ba,Ca) MoO{sub 4} For The Immobilization Of Mo-Rich Nuclear Waste

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, Kyle [Savannah River Site (SRS), Aiken, SC (United States); Marra, James [Savannah River Site (SRS), Aiken, SC (United States); Fox, Kevin [Savannah River Site (SRS), Aiken, SC (United States); Reppert, Jason [Savannah River Site (SRS), Aiken, SC (United States); Crum, Jarrod [Paci fic Northwest National Laboratory , Richland, WA (United States); Tang, Ming [Los Alamos National Laboratory , Los Alamos, NM (United States)

    2012-09-17

    Crystalline and glass composite materials are currently being investigated for the immobilization of combined High Level Waste (HLW) streams resulting from potential commercial fuel reprocessing scenarios. Several of these potential waste streams contain elevated levels of transition metal elements such as molybdenum (Mo). Molybdenum has limited solubility in typical silicate glasses used for nuclear waste immobilization. Under certain chemical and controlled cooling conditions, a powellite (Ba,Ca)MoO{sub 4} crystalline structure can be formed by reaction with alkaline earth elements. In this study, single phase BaMoO{sub 4} and CaMoO{sub 4} were formed from carbonate and oxide precursors demonstrating the viability of Mo incorporation into glass, crystalline or glass composite materials by a melt and crystallization process. X-ray diffraction, photoluminescence, and Raman spectroscopy indicated a long range ordered crystalline structure. In-situ electron irradiation studies indicated that both CaMoO{sub 4} and BaMoO{sub 4} powellite phases exhibit radiation stability up to 1000 years at anticipated doses with a crystalline to amorphous transition observed after 1 X 10{sup 13} Gy. Aqueous durability determined from product consistency tests (PCT) showed low normalized release rates for Ba, Ca, and Mo (<0.05 g/m{sup 2}).

  20. Preferred Orientation Contribution to the Anisotropic Normal State Resistivity in Superconducting Melt-Cast Processed Bi2Sr2CaCu2O8+δ

    Directory of Open Access Journals (Sweden)

    Aline Dellicour

    2017-05-01

    Full Text Available We describe how the contribution of crystallographic texture to the anisotropy of the resistivity of polycrystalline samples can be estimated by averaging over crystallographic orientations through a geometric mean approach. The calculation takes into account the orientation distribution refined from neutron diffraction data and literature values for the single crystal resistivity tensor. The example discussed here is a melt-cast processed Bi2Sr2CaCu2O8+δ (Bi-2212 polycrystalline tube in which the main texture component is a <010> fiber texture with relatively low texture strength. Experimentally-measured resistivities along the longitudinal, radial, and tangential directions of the Bi-2212 tube were compared to calculated values and found to be of the same order of magnitude. Calculations for this example and additional simulations for various texture strengths and single crystal resistivity anisotropies confirm that in the case of highly anisotropic phases such as Bi-2212, even low texture strengths have a significant effect on the anisotropy of the resistivity in polycrystalline samples.

  1. Preferred Orientation Contribution to the Anisotropic Normal State Resistivity in Superconducting Melt-Cast Processed Bi₂Sr₂CaCu₂O8+δ.

    Science.gov (United States)

    Dellicour, Aline; Vertruyen, Benedicte; Rikel, Mark O; Lutterotti, Luca; Pautrat, Alain; Ouladdiaf, Bachir; Chateigner, Daniel

    2017-05-15

    We describe how the contribution of crystallographic texture to the anisotropy of the resistivity of polycrystalline samples can be estimated by averaging over crystallographic orientations through a geometric mean approach. The calculation takes into account the orientation distribution refined from neutron diffraction data and literature values for the single crystal resistivity tensor. The example discussed here is a melt-cast processed Bi₂Sr₂CaCu₂O 8+δ (Bi-2212) polycrystalline tube in which the main texture component is a fiber texture with relatively low texture strength. Experimentally-measured resistivities along the longitudinal, radial, and tangential directions of the Bi-2212 tube were compared to calculated values and found to be of the same order of magnitude. Calculations for this example and additional simulations for various texture strengths and single crystal resistivity anisotropies confirm that in the case of highly anisotropic phases such as Bi-2212, even low texture strengths have a significant effect on the anisotropy of the resistivity in polycrystalline samples.

  2. Challenges in Melt Furnace Tests

    Science.gov (United States)

    Belt, Cynthia

    2014-09-01

    Measurement is a critical part of running a cast house. Key performance indicators such as energy intensity, production (or melt rate), downtime (or OEE), and melt loss must all be understood and monitored on a weekly or monthly basis. Continuous process variables such as bath temperature, flue temperature, and furnace pressure should be used to control the furnace systems along with storing the values in databases for later analysis. While using measurement to track furnace performance over time is important, there is also a time and place for short-term tests.

  3. Fatigue behavior of thin-walled grade 2 titanium samples processed by selective laser melting. Application to life prediction of porous titanium implants.

    Science.gov (United States)

    Lipinski, P; Barbas, A; Bonnet, A-S

    2013-12-01

    Because of its biocompatibility and high mechanical properties, the commercially pure grade 2 titanium (CPG2Ti) is largely used for fabrication of patient specific implants or hard tissue substitutes with complex shape. To avoid the stress-shielding and help their colonization by bone, prostheses with a controlled porosity are designed. The selective laser melting (SLM) is well adapted to manufacture such geometrically complicated structures constituted by struts with rough surfaces and relatively small diameters. Few studies were dedicated to characterize the fatigue properties of SLM processed samples and bulk parts. They followed conventional or standard protocols. The fatigue behavior of standard samples is very different from the one of porous raw structures. In this study, the SLM made "as built" (AB) and "heat treated" (HT) tubular samples were tested in fatigue. Wöhler curves were determined in both cases. The obtained endurance limits were equal to σD(AB)=74.5MPa and σD(HT)=65.7MPa, respectively. The heat treatment worsened the endurance limit by relaxation of negative residual stresses measured on the external surface of the samples. Modified Goodman diagram was established for raw specimens. Porous samples, based on the pattern developed by Barbas et al. (2012), were manufactured by SLM. Fatigue tests and finite element simulations performed on these samples enabled the determination of a simple rule of fatigue assessment. The method based on the stress gradient appeared as the best approach to take into account the notch influence on the fatigue life of CPG2Ti structures with a controlled porosity. The direction dependent apparent fatigue strength was found. A criterion based on the effective, or global, nominal stress was proposed taking into account the anisotropy of the porous structures. Thanks to this criterion, the usual calculation methods can be used to design bone substitutes, without a precise modelling of their internal fine porosity.

  4. Quasi-equilibrium melting of quartzite upon extreme friction

    Science.gov (United States)

    Lee, Sung Keun; Han, Raehee; Kim, Eun Jeong; Jeong, Gi Young; Khim, Hoon; Hirose, Takehiro

    2017-06-01

    The friction on fault planes that controls how rocks slide during earthquakes decreases significantly as a result of complex fault-lubrication processes involving frictional melting. Fault friction has been characterized in terms of the preferential melting of minerals with low melting points--so-called disequilibrium melting. Quartz, which has a high melting temperature of about 1,726 °C and is a major component of crustal rocks, is not expected to melt often during seismic slip. Here we use high-velocity friction experiments on quartzite to show that quartz can melt at temperatures of 1,350 to 1,500 °C. This implies that quartz within a fault plane undergoing rapid friction sliding could melt at substantially lower temperatures than expected. We suggest that depression of the melting temperature is caused by the preferential melting of ultra-fine particles and metastable melting of β-quartz at about 1,400 °C during extreme frictional slip. The results for quartzite are applicable to complex rocks because of the observed prevalence of dynamic grain fragmentation, the preferential melting of smaller grains and the kinetic preference of β-quartz formation during frictional sliding. We postulate that frictional melting of quartz on a fault plane at temperatures substantially below the melting temperature could facilitate slip-weakening and lead to large earthquakes.

  5. The infidelity of melt inclusions?

    Science.gov (United States)

    Kent, A. J.

    2008-12-01

    Melt inclusions provide important information about magmatic systems and represent unique records of magma composition and evolution. However, it is also clear that melt inclusions do not necessarily constitute a petrological 'magic bullet', and potential exists for trapped melt compositions to be modified by a range of inclusion-specific processes. These include trapping of diffusional boundary layers, crystallization of the host mineral after trapping and dissolution of co-trapped minerals during homogenization, diffusional exchange between trapped liquid and the host mineral and external melt, and cryptic alteration of trapped material during weathering or hydrothermal alteration. It clearly important to identify when melt inclusions are unmodified, and which compositional indices represent the most robust sources of petrogenetic information. In this presentation I review and discuss various approaches for evaluating compositions and compositional variations in inclusion suites. An overriding principle is that the variations evident in melt inclusions should be able to be understood in terms of petrological processes that are known, or can be reasonably inferred to also effect bulk magma compositions. One common approach is to base petrological conclusions on species that should be more robust, and many workers use variations in incompatible trace elements for this purpose. However important information may also be obtained from a comparison of variations in melt inclusions and the lavas that host them, and in most cases this comparison is the key to identifying inclusions and suites that are potentially suspect. Comparisons can be made between individual inclusions and lavas, although comparison of average inclusion composition and the host lava, after correction for differences in crystal fractionation, may also be valuable. An important extension of this is the comparison of the variability of different species in inclusions and host lavas. This also provides

  6. Behavior of metals in ash melting and gasification-melting of municipal solid waste (MSW).

    Science.gov (United States)

    Jung, C H; Matsuto, T; Tanaka, N

    2005-01-01

    In this study, metal behavior in ash-melting and municipal solid waste (MSW) gasification-melting facilities were investigated. Eight ash-melting and three MSW gasification-melting facilities with a variety of melting processes and feedstocks were selected. From each facility, melting furnace fly ash (MFA) and molten slag were sampled, and feedstock of the ash-melting processes was also taken. For the ash melting process, the generation rate of MFA was well correlated with the ratio of incineration fly ash (IFA) in feedstock, and this was because MFA was formed mostly by mass transfer from IFA and a limited amount from bottom ash (BA). Distribution ratios of metal elements to MFA were generally determined by volatility of the metal element, but chlorine content in feedstock had a significant effect on Cu and a marginal effect on Pb. Distribution ratio of Zn to MFA was influenced by the oxidizing atmosphere in the furnace. High MFA generation and distribution ratio of non-volatile metals to MFA in gasification-melting facilities was probably caused by carry-over of fine particles to the air pollution control system due to large gas volume. Finally, dilution effect was shown to have a significant effect on metal concentration in MFA.

  7. ESR melting under constant voltage conditions

    Energy Technology Data Exchange (ETDEWEB)

    Schlienger, M.E.

    1997-02-01

    Typical industrial ESR melting practice includes operation at a constant current. This constant current operation is achieved through the use of a power supply whose output provides this constant current characteristic. Analysis of this melting mode indicates that the ESR process under conditions of constant current is inherently unstable. Analysis also indicates that ESR melting under the condition of a constant applied voltage yields a process which is inherently stable. This paper reviews the process stability arguments for both constant current and constant voltage operation. Explanations are given as to why there is a difference between the two modes of operation. Finally, constant voltage process considerations such as melt rate control, response to electrode anomalies and impact on solidification will be discussed.

  8. Selective Laser Ablation and Melting, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In this project Advratech will develop a new additive manufacturing (AM) process called Selective Laser Ablation and Melting (SLAM). The key innovation in this...

  9. Dynamics of Melting and Melt Migration as Inferred from Incompatible Trace Element Abundance in Abyssal Peridotites

    Science.gov (United States)

    Peng, Q.; Liang, Y.

    2008-12-01

    To better understand the melting processes beneath the mid-ocean ridge, we developed a simple model for trace element fractionation during concurrent melting and melt migration in an upwelling steady-state mantle column. Based on petrologic considerations, we divided the upwelling mantle into two regions: a double- lithology upper region where high permeability dunite channels are embedded in a lherzolite/harzburgite matrix, and a single-lithology lower region that consists of partially molten lherzolite. Melt generated in the single lithology region migrates upward through grain-scale diffuse porous flow, whereas melt in the lherzolite/harzburgite matrix in the double-lithology region is allowed to flow both vertically through the overlying matrix and horizontally into its neighboring dunite channels. There are three key dynamic parameters in our model: degree of melting experienced by the single lithology column (Fd), degree of melting experienced by the double lithology column (F), and a dimensionless melt suction rate (R) that measures the accumulated rate of melt extraction from the matrix to the channel relative to the accumulated rate of matrix melting. In terms of trace element fractionation, upwelling and melting in the single lithology column is equivalent to non-modal batch melting (R = 0), whereas melting and melt migration in the double lithology region is equivalent to a nonlinear combination of non-modal batch and fractional melting (0 abyssal peridotite, we showed, with the help of Monte Carlo simulations, that it is difficult to invert for all three dynamic parameters from a set of incompatible trace element data with confidence. However, given Fd, it is quite possible to constrain F and R from incompatible trace element abundances in residual peridotite. As an illustrative example, we used the simple melting model developed in this study and selected REE and Y abundance in diopside from abyssal peridotites to infer their melting and melt migration

  10. Nanotexturing of surfaces to reduce melting point.

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Ernest J.; Zubia, David (University of Texas at El Paso El Paso, TX); Mireles, Jose (Universidad Aut%C3%94onoma de Ciudad Ju%C3%94arez Ciudad Ju%C3%94arez, Mexico); Marquez, Noel (University of Texas at El Paso El Paso, TX); Quinones, Stella (University of Texas at El Paso El Paso, TX)

    2011-11-01

    This investigation examined the use of nano-patterned structures on Silicon-on-Insulator (SOI) material to reduce the bulk material melting point (1414 C). It has been found that sharp-tipped and other similar structures have a propensity to move to the lower energy states of spherical structures and as a result exhibit lower melting points than the bulk material. Such a reduction of the melting point would offer a number of interesting opportunities for bonding in microsystems packaging applications. Nano patterning process capabilities were developed to create the required structures for the investigation. One of the technical challenges of the project was understanding and creating the specialized conditions required to observe the melting and reshaping phenomena. Through systematic experimentation and review of the literature these conditions were determined and used to conduct phase change experiments. Melting temperatures as low as 1030 C were observed.

  11. Melt processed crystalline ceramic waste forms for advanced nuclear fuel cycles: CRP T21027 1813: Processing technologies for high level waste, formulation of matrices and characterization of waste forms, Task 17208: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Amoroso, J. W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Marra, J. C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-08-26

    A multi-phase ceramic waste form is being developed at the Savannah River National Laboratory (SRNL) for treatment of secondary waste streams generated by reprocessing commercial spent nuclear. The envisioned waste stream contains a mixture of transition, alkali, alkaline earth, and lanthanide metals. Ceramic waste forms are tailored (engineered) to incorporate waste components as part of their crystal structure based on knowledge from naturally found minerals containing radioactive and non-radioactive species similar to the radionuclides of concern in wastes from fuel reprocessing. The ability to tailor ceramics to mimic naturally occurring crystals substantiates the long term stability of such crystals (ceramics) over geologic timescales of interest for nuclear waste immobilization [1]. A durable multi-phase ceramic waste form tailored to incorporate all the waste components has the potential to broaden the available disposal options and thus minimize the storage and disposal costs associated with aqueous reprocessing. This report summarizes results from three years of work on the IAEA Coordinated Research Project on “Processing technologies for high level waste, formulation of matrices and characterization of waste forms” (T21027), and specific task “Melt Processed Crystalline Ceramic Waste Forms for Advanced Nuclear Fuel Cycles” (17208).

  12. Melt processed crystalline ceramic waste forms for advanced nuclear fuel cycles: CRP T21027 1813: Processing technologies for high level waste, formulation of matrices and characterization of waste forms, task 17208: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Amoroso, J. W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Marra, J. C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-08-26

    A multi-phase ceramic waste form is being developed at the Savannah River National Laboratory (SRNL) for treatment of secondary waste streams generated by reprocessing commercial spent nuclear. The envisioned waste stream contains a mixture of transition, alkali, alkaline earth, and lanthanide metals. Ceramic waste forms are tailored (engineered) to incorporate waste components as part of their crystal structure based on knowledge from naturally found minerals containing radioactive and non-radioactive species similar to the radionuclides of concern in wastes from fuel reprocessing. The ability to tailor ceramics to mimic naturally occurring crystals substantiates the long term stability of such crystals (ceramics) over geologic timescales of interest for nuclear waste immobilization [1]. A durable multi-phase ceramic waste form tailored to incorporate all the waste components has the potential to broaden the available disposal options and thus minimize the storage and disposal costs associated with aqueous reprocessing. This report summarizes results from three years of work on the IAEA Coordinated Research Project on “Processing technologies for high level waste, formulation of matrices and characterization of waste forms” (T21027), and specific task “Melt Processed Crystalline Ceramic Waste Forms for Advanced Nuclear Fuel Cycles” (17208).

  13. Preparation and optimization of thermoelectric properties of Bi2Te3 based alloys using the waste particles as raw materials from the cutting process of the zone melting crystal rods

    Science.gov (United States)

    Xiang, Qiusheng; Fan, Xi'an; Han, Xuewu; Zhang, Chengcheng; Hu, Jie; Feng, Bo; Jiang, Chengpeng; Li, Guangqiang; Li, Yawei; He, Zhu

    2017-12-01

    The p-type Bi2Te3 alloys were prepared using the waste particles from the cutting process of the zone melting crystal rods as the main raw materials by impurity removal process including washing, carbon monoxide reduction and vacuum metallurgical process. The thermoelectric properties of the Bi2Te3 based bulk materials were optimized by component adjustment, second smelting and resistance pressing sintering (RPS) process. All evidences confirmed that most of impurities from the line cutting process and the oxidation such as Sb2O3, Bi2O3 and Bi2Te4O11 could be removed by carbon monoxide reduction and vacuum metallurgical process adopted in this work, and the recycling yield was higher than 97%. Appropriate component adjustment treatment was used to optimize the carrier content and corresponding thermoelectric properties. Lastly, a Bi0.36Sb1.64Te3 bulk was obtained and its power factor (PF) could reach 4.24 mW m-1 K-2 at 300 K and the average PF value was over 3.2 mW m-1 K-2 from 300 K to 470 K, which was equivalent with the thermoelectric performance of the zone melting products from high purity elements Bi, Te and Sb. It was worth mentioning that the recovery process introduced here was a simple, low-cost, high recovery rate and green recycling technology.

  14. Petrogenesis of ultramafic rocks from the eastern Orhaneli ophiolite, NW Turkey: Hints on the initiation and evolution of melt-peridotite interaction processes within a heterogeneously depleted mantle section

    Science.gov (United States)

    Uysal, Ibrahim; Dokuz, Abdurrahman; Kapsiotis, Argyrios; Saka, Samet; Karslı, Orhan; Kaliwoda, Melanie; Müller, Dirk

    2017-10-01

    The eastern Orhaneli ophiolite in NW Anatolia (Turkey) consists of voluminous dunite and minor harzburgite intruded by clinopyroxenite veins. Harzburgite contains spinel of low Cr# [100 × Cr/(Cr + Al) = 40-45] and diopside of low Al2O3 and TiO2 contents, whereas dunite contains spinel of higher Cr# (62-82) and diopside (blebs) (even more) depleted in Al2O3 and TiO2 (than harzburgite). The concentrations of Heavy Rare Earth Elements (HREE) in harzburgite are consistent with derivation of this type of peridotite from 19% dry melting of a fertile mantle protolith at a MOR regime. Dunites have lower concentrations of HREE than harzburgite implying that dunites were generated by higher degrees (>30%) of (cumulative) melting of the same protolith. Furthermore, the characteristic U-shapes of the chondrite-normalized REE-patterns of dunites indicate the involvement of hydrous melt-peridotite interaction processes in their genesis. Nevertheless, a set of mosaic-in-texture dunite samples contain olivine that has lower Fo# [100 × Mg/(Mg + Fe2+)] and NiO contents than olivine in harzburgite. These dunites are probably of cumulate origin as it is also indicated by their enrichment in Pt and Pd (≤17.92 ppb). Micro-textural and Re-Os isotopic data support that clinopyroxenite intrusions do not have a pure magmatic origin and their formation was partly controlled by metasomatic processes. Overall data indicate that the eastern Orhaneli ultramafic rocks have a complex petrological history including various stages of partial melting, metasomatism and magmatism in an evolving from MOR to SSZ geotectonic setting.

  15. Melt Cast High Explosives

    Directory of Open Access Journals (Sweden)

    Stanisław Cudziło

    2014-12-01

    Full Text Available [b]Abstract[/b]. This paper reviews the current state and future developments of melt-cast high explosives. First the compositions, properties and methods of preparation of trinitrotoluene based (TNT conventional mixtures with aluminum, hexogen (RDX or octogen (HMX are described. In the newer, less sensitive explosive formulations, TNT is replaced with dinitroanisole (DNANDNANDNAN and nitrotriazolone (NTONTONTO, nitroguanidine (NG or ammonium perchlorate (AP are the replacement for RDRDX and HMX. Plasticized wax or polymer-based binder systems for melt castable explosives are also included. Hydroxyl terminated polybutadiene (HPTB is the binder of choice, but polyethylene glycol, and polycaprolactone with energetic plasticizers are also used. The most advanced melt-cast explosives are compositions containing energetic thermoplastic elastomers and novel highly energetic compounds (including nitrogen rich molecules in whose particles are nanosized and practically defect-less.[b]Keywords[/b]: melt-cast explosives, detonation parameters

  16. Melt fracture revisited

    Energy Technology Data Exchange (ETDEWEB)

    Greenberg, J. M.

    2003-07-16

    In a previous paper the author and Demay advanced a model to explain the melt fracture instability observed when molten linear polymer melts are extruded in a capillary rheometer operating under the controlled condition that the inlet flow rate was held constant. The model postulated that the melts were a slightly compressible viscous fluid and allowed for slipping of the melt at the wall. The novel feature of that model was the use of an empirical switch law which governed the amount of wall slip. The model successfully accounted for the oscillatory behavior of the exit flow rate, typically referred to as the melt fracture instability, but did not simultaneously yield the fine scale spatial oscillations in the melt typically referred to as shark skin. In this note a new model is advanced which simultaneously explains the melt fracture instability and shark skin phenomena. The model postulates that the polymer is a slightly compressible linearly viscous fluid but assumes no slip boundary conditions at the capillary wall. In simple shear the shear stress {tau}and strain rate d are assumed to be related by d = F{tau} where F ranges between F{sub 2} and F{sub 1} > F{sub 2}. A strain rate dependent yield function is introduced and this function governs whether F evolves towards F{sub 2} or F{sub 1}. This model accounts for the empirical observation that at high shears polymers align and slide more easily than at low shears and explains both the melt fracture and shark skin phenomena.

  17. Nanoparticle-induced unusual melting and solidification behaviours of metals

    Science.gov (United States)

    Ma, Chao; Chen, Lianyi; Cao, Chezheng; Li, Xiaochun

    2017-01-01

    Effective control of melting and solidification behaviours of materials is significant for numerous applications. It has been a long-standing challenge to increase the melted zone (MZ) depth while shrinking the heat-affected zone (HAZ) size during local melting and solidification of materials. In this paper, nanoparticle-induced unusual melting and solidification behaviours of metals are reported that effectively solve this long-time dilemma. By introduction of Al2O3 nanoparticles, the MZ depth of Ni is increased by 68%, while the corresponding HAZ size is decreased by 67% in laser melting at a pulse energy of 0.18 mJ. The addition of SiC nanoparticles shows similar results. The discovery of the unusual melting and solidification of materials that contain nanoparticles will not only have impacts on existing melting and solidification manufacturing processes, such as laser welding and additive manufacturing, but also on other applications such as pharmaceutical processing and energy storage.

  18. Radioactive waste melting furnace

    International Nuclear Information System (INIS)

    Nakayama, Junpei.

    1997-01-01

    The present invention provides a radioactive waste melting furnace excellent in heat insulating property, capable of exchanging only refractory materials with lesser amount of contamination. Namely, an heat insulation layer is disposed on the outer wall of the melting furnace. A refractory layer is disposed on the inner wall being in contact with molten materials in the melting furnace. A metal vessel covering the refractory layer is interposed between the heat insulation layer and the refractory layer. In addition, a metal outer shell covering the heat insulation layer is disposed on the heat insulation layer on the outer wall of the melting furnace. Bricks comprising, for example, alumina, carbon, zircon, magnesia or chromia having a low heat conductivity are used for the outer wall heat insulation layer irrespective of the melting performance. The refractory layer on the inner wall is made of bricks comprising chromia, alumina and zircon as molten materials of low basicity and chromia and magnesia as molten materials of high basicity. The materials of the metal vessel may be ordinary carbon steels, cast irons, or stainless steels. The refractory layer is taken out from the melting furnace together with the metal vessel, and only the refractory layer can be removed. Radiation contamination is eliminated. The metal vessel can be used again. (I.S.)

  19. Mid Ocean Ridge Processes at Very Low Melt Supply : Submersible Exploration of Smooth Ultramafic Seafloor at the Southwest Indian Ridge, 64 degree E

    Science.gov (United States)

    Cannat, M.; Agrinier, P.; Bickert, M.; Brunelli, D.; Hamelin, C.; Lecoeuvre, A.; Lie Onstad, S.; Maia, M.; Prampolini, M.; Rouméjon, S.; Vitale Brovarone, A.; Besançon, S.; Assaoui, E. M.

    2017-12-01

    Mid-ocean ridges are the Earth's most extensive and active volcanic chains. They are also, particularly at slow spreading rates, rift zones, where plate divergence is in part accommodated by faults. Large offset normal faults, also called detachments, are characteristic of slow-spreading ridges, where they account for the widespread emplacement of mantle-derived rocks at the seafloor. In most cases, these detachments occur together with ridge magmatism, with melt injection and faulting interacting to shape the newly formed oceanic lithosphere. Here, we seek to better understand these interactions and their effects on oceanic accretion by studying the end-member case of a ridge where magmatism is locally almost absent. The portion of the Southwest Indian ridge we are studying has an overal low melt supply, focused to discrete axial volcanoes, leaving almost zero melt to intervening sections of the axial valley. One of these nearly amagmatic section of the ridge, located at 64°E, has been the focus of several past cruises (sampling, mapping and seismic experiments). Here we report on the most recent cruise to the area (RV Pourquoi Pas? with ROV Victor; dec-jan 2017), during which we performed high resolution mapping, submersible exploration and sampling of the ultramafic seafloor and of sparse volcanic formations. Our findings are consistent with the flip-flop detachment hypothesis proposed for this area by Sauter et al. (Nature Geosciences, 2013; ultramafic seafloor forming in the footwall of successive detachment faults, each cutting into the footwall of the previous fault, with an opposite polarity). Our observations also document the extent and geometry of deformation in the footwall of a young axial detachment, the role of mass-wasting for the evolution of this detachment, and provide spectacular evidence for serpentinization-related hydrothermal circulation and for spatial links between faults and volcanic eruptions.

  20. Terrestrial impact melt rocks and glasses

    Science.gov (United States)

    Dressler, B. O.; Reimold, W. U.

    2001-12-01

    The effects of meteorite and comet impact on Earth are rock brecciation, the formation of shock metamorphic features, rock melting, and the formation of impact structures, i.e. simple craters, complex craters, and multi-ring basins. Large events, such as the 65-Ma Chicxulub impact, are believed to have had catastrophic environmental effects that profoundly influenced the development of life on Earth. In this review, an attempt is made to summarize some of the voluminous literature on impact melting, one important aspect of planetary impact, provide some comments on this process, and to make suggestions for future research. The products of impact melting are glasses, impact melt rocks, and pseudotachylites. Our treatise deals mainly with the geological setting, petrography, and major-element chemistry of melt rocks and glasses. Impact glasses, in several petrographic aspects, are similar to volcanic glasses, but they are associated with shock metamorphosed mineral and rock fragments and, in places, with siderophile element anomalies suggestive of meteoritic contamination. They are found in allogenic breccia deposits within (fall-back 'suevite') and outside (fall-out 'suevite') impact craters and, as spherules, in distal ejecta. Large events, such as the K/T boundary Chicxulub impact, are responsible for the formation of worldwide ejecta horizons which are associated with siderophile element anomalies and shock metamorphosed mineral and rock debris. Impact glasses have a bulk chemical composition that is homogeneous but exemptions to this rule are common. On a microscopic scale, however, impact glasses are commonly strikingly heterogeneous. Tektites are glasses ejected from craters over large distances. They are characterized by very low water and volatile contents and element abundances and ratios that are evidence that tektites formed by melting of upper crustal, sedimentary rocks. Four tektite strewn-fields are known, three of which can be tied to specific impact

  1. Vanadium, sulfur, and iron valences in melt inclusions as a window into magmatic processes: A case study at Nyamuragira volcano, Africa

    Science.gov (United States)

    Head, Elisabet; Lanzirotti, Antonio; Newville, Matthew; Sutton, Stephen

    2018-04-01

    This study describes microscale sulfur (S), vanadium (V), and iron (Fe) K-edge X-ray absorption near edge structure (μ-XANES) spectroscopy measurements on olivine-hosted melt inclusions (MI) preserved in tephras (1986 and 2006) and lavas (1938 and 1948) erupted from Nyamuragira volcano (D.R. Congo, Africa). The S, V, and Fe spectroscopic data are used to constrain the evolution of oxygen fugacity (fO2) and sulfur speciation for the entrapped melts. Melt inclusions from lavas show evidence of post-entrapment crystallization and were thus reheated prior to μ-XANES analysis. The MI from tephra show no evidence of post-entrapment crystallization and were, therefore, not reheated. Sulfur, V, and Fe μ-XANES results from 1938, 1948, and 2006 eruptive materials are all similar within analytical uncertainty and provide similar average calculated melt fO2's based on XANES oxybarometry. However, olivine-hosted MI from the 1986 tephras yield significantly different S, V, and Fe XANES spectra when compared to MI from the other eruptions, with disagreement between calculated fO2's from the three valence state oxybarometers beyond the uncertainty of the calibration models. Their V μ-XANES spectra are also significantly more ordered and yield more reduced average V valence. The S μ-XANES spectra display a significantly more intense low-energy spectral resonance, which indicates differences in Fe-S bonding character, and greater variability in their measured sulfate content. These V and S spectroscopic features are best explained by crystallization of sub-micrometer magnetite and sulfide crystallites within the 1986 inclusions. The sensitivity of XANES spectroscopy to short-range order allows these crystallites to be recognized even though they are not easily detected by imaging analysis. This shows that V and S μ-XANES are potentially highly sensitive tools for identifying the presence of volumetrically minor amounts of spinel and sulfide within inclusions extracted from

  2. Scrap uranium recycling via electron beam melting

    International Nuclear Information System (INIS)

    McKoon, R.

    1993-11-01

    A program is underway at the Lawrence Livermore National Laboratory (LLNL) to recycle scrap uranium metal. Currently, much of the material from forging and machining processes is considered radioactive waste and is disposed of by oxidation and encapsulation at significant cost. In the recycling process, uranium and uranium alloys in various forms will be processed by electron beam melting and continuously cast into ingots meeting applicable specifications for virgin material. Existing vacuum processing facilities at LLNL are in compliance with all current federal and state environmental, safety and health regulations for the electron beam melting and vaporization of uranium metal. One of these facilities has been retrofitted with an auxiliary electron beam gun system, water-cooled hearth, crucible and ingot puller to create an electron beam melt furnace. In this furnace, basic process R ampersand D on uranium recycling will be performed with the goal of eventual transfer of this technology to a production facility

  3. An investigation into the effect of formulation variables and process parameters on characteristics of granules obtained by in situ fluidized hot melt granulation.

    Science.gov (United States)

    Mašić, Ivana; Ilić, Ilija; Dreu, Rok; Ibrić, Svetlana; Parojčić, Jelena; Durić, Zorica

    2012-02-28

    The aim of this study was to investigate the influence of binder content, binder particle size, granulation time and inlet air flow rate on granule size and size distribution, granule shape and flowability, as well as on drug release rate. Hydrophilic (polyethyleneglycol 2000) and hydrophobic meltable binder (glyceryl palmitostearate) were used for in situ fluidized hot melt granulation. Granule size was mainly influenced by binder particle size. Binder content was shown to be important for narrow size distribution and good flow properties. The results obtained indicate that conventional fluid bed granulator may be suitable for production of highly spherical agglomerates, particularly when immersion and layering is dominant agglomeration mechanism. Granule shape was affected by interplay of binder content, binder particle size and granulation time. Solid state analysis confirmed unaltered physical state of the granulate components and the absence of interactions between the active and excipients. Besides the nature and amount of binder, the mechanism of agglomerate formation seems to have an impact on drug dissolution rate. The results of the present study indicate that fluidized hot melt granulation is a promising powder agglomeration technique for spherical granules production. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Investigation of Melting Dynamics of Hafnium Clusters.

    Science.gov (United States)

    Ng, Wei Chun; Lim, Thong Leng; Yoon, Tiem Leong

    2017-03-27

    Melting dynamics of hafnium clusters are investigated using a novel approach based on the idea of the chemical similarity index. Ground state configurations of small hafnium clusters are first derived using Basin-Hopping and Genetic Algorithm in the parallel tempering mode, employing the COMB potential in the energy calculator. These assumed ground state structures are verified by using the Low Lying Structures (LLS) method. The melting process is carried out either by using the direct heating method or prolonged simulated annealing. The melting point is identified by a caloric curve. However, it is found that the global similarity index is much more superior in locating premelting and total melting points of hafnium clusters.

  5. Melting temperature of graphite

    International Nuclear Information System (INIS)

    Korobenko, V.N.; Savvatimskiy, A.I.

    2001-01-01

    Full Text: Pulse of electrical current is used for fast heating (∼ 1 μs) of metal and graphite specimens placed in dielectric solid media. Specimen consists of two strips (90 μm in thick) placed together with small gap so they form a black body model. Quasy-monocrystal graphite specimens were used for uniform heating of graphite. Temperature measurements were fulfilled with fast pyrometer and with composite 2-strip black body model up to melting temperature. There were fulfilled experiments with zirconium and tungsten of the same black body construction. Additional temperature measurements of liquid zirconium and liquid tungsten are made. Specific heat capacity (c P ) of liquid zirconium and of liquid tungsten has a common feature in c P diminishing just after melting. It reveals c P diminishing after melting in both cases over the narrow temperature range up to usual values known from steady state measurements. Over the next wide temperature range heat capacity for W (up to 5000 K) and Zr (up to 4100 K) show different dependencies of heat capacity on temperature in liquid state. The experiments confirmed a high quality of 2-strip black body model used for graphite temperature measurements. Melting temperature plateau of tungsten (3690 K) was used for pyrometer calibration area for graphite temperature measurement. As a result, a preliminary value of graphite melting temperature of 4800 K was obtained. (author)

  6. DWPF Macrobatch 2 Melt Rate Tests

    Energy Technology Data Exchange (ETDEWEB)

    Stone, M.E.

    2001-01-03

    The Defense Waste Processing Facility (DWPF) canister production rate must be increased to meet canister production goals. Although a number of factors exist that could potentially increase melt rate, this study focused on two: (1) changes in frit composition and (2) changes to the feed preparation process to alter the redox of the melter feed. These two factors were investigated for Macrobatch 2 (sludge batch 1B) utilizing crucible studies and a specially designed ''melt rate'' furnace. Other potential factors that could increase melt rate include: mechanical mixing via stirring or the use of bubblers, changing the power skewing to redistribute the power input to the melter, and elimination of heat loss (e.g. air in leakage). The melt rate testing in FY00 demonstrated that melt rate can be improved by adding a different frit or producing a much more reducing glass by the addition of sugar as a reductant. The frit that melted the fastest in the melt rate testing was Frit 165. A paper stud y was performed using the Product Composition Control System (PCCS) to determine the impact on predicted glass viscosity, liquidus, durability, and operating window if the frit was changed from Frit 200 to Frit 165. PCCS indicated that the window was very similar for both frits. In addition, the predicted viscosity of the frit 165 glass was 46 poise versus 84 poise for the Frit 200 glass. As a result, a change from Frit 200 to Frit 165 is expected to increase the melt rate in DWPF without decreasing waste loading.

  7. Effect of the strain-induced melt activation (SIMA) process on the tensile properties of a new developed super high strength aluminum alloy modified by Al-5Ti-1B grain refiner

    Energy Technology Data Exchange (ETDEWEB)

    Haghparast, Amin [School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nourimotlagh, Masoud [Young Researchers Club, Dareshahr Branch, Islamic Azad university (Iran, Islamic Republic of); Alipour, Mohammad, E-mail: Alipourmo@ut.ac.ir [School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2012-09-15

    In this study, the effect of Al-5Ti-1B grain refiners and modified strain-induced melt activation process on an Al-Zn-Mg-Cu alloy was studied. The optimum level of Ti was found to be 0.1 wt.%. The specimens subjected to deformation ratio of 40% (at 300 Degree-Sign C) and various heat treatment times (10-40 min) and temperature (550-600 Degree-Sign C) regimes were characterized in this study. Reheating condition to obtain a fine globular microstructure was optimized. Microstructural examinations were conducted by optical and scanning electron microscopy coupled with an energy dispersive spectrometry. The optimum temperature and time in strain-induced melt activation process are 575 Degree-Sign C and 20 min, respectively. T6 heat treatment including quenching to room temperature and aging at 120 Degree-Sign C for 24 h was employed to reach to the maximum strength. Significant improvements in mechanical properties were obtained with the addition of grain refiner combined with T6 heat treatment. After the T6 heat treatment, the average tensile strength increased from 283 MPa to 587 and 332 MPa to 617 for samples refined with 2 wt.% Al-5Ti-1B before and after strain-induced melt activation process and extrusion process, respectively. Ultimate strength of Ti-refined specimens without SIMA process has a lower value than globular microstructure specimens after SIMA and extrusion process. - Highlights: Black-Right-Pointing-Pointer The effect of Al-5Ti-1B on the aluminum alloy produced by SIMA process was studied. Black-Right-Pointing-Pointer Al-5Ti-1B is an effective in reducing the grain and reagent fine microstructure. Black-Right-Pointing-Pointer Reheating condition to obtain a fine globular microstructure was optimized. Black-Right-Pointing-Pointer The optimum temperature and time in SIMA process are 575 Degree-Sign C and 20 min respectively. Black-Right-Pointing-Pointer UTS of globular structure specimens have a more value than Ti-refined specimens.

  8. Entangled Polymer Melts in Extensional Flow

    DEFF Research Database (Denmark)

    Hengeller, Ludovica

    . On the other hand, addition of low-volatility solvents to polymers is also a common industrial practice that others a means for lowering the Tg of the polymers. Moreover industrial polymers present a wide distribution of chain lengths and/or branched architectures that strongly influence their response....... Understanding the behaviour of polymer melts and solutions in complex non-linearflows is crucial for the design of polymeric materials and polymer processes. Through rheological characterization, in shear and extensional flow, of model polymer systems,i.e. narrow molar mass distribution polymer melts......Many commercial materials derived from synthetic polymers exhibit a complex response under different processing operations such as fiber formation, injection moulding,film blowing, film casting or coatings. They can be processed both in the solid or in the melted state. Often they may contain two...

  9. Experimental study of thermocapillary convection in a germanium melt

    Science.gov (United States)

    Gorbunov, Leonid A.

    1996-08-01

    The present paper is dedicated to the experimental investigation of thermocapillary convection (TCC) in semiconductor melts. The investigation showed that in the process of single crystal growth under terrestrial conditions TCC could be compared to thermogravity convection (TGC) for a number of semiconductor melts such as Ge, Si, GaAs. But in comparatively thin layers with H container radius) it can dominate over TGC. The experiments were conducted with a Ge melt. Oxide particle tracers were used to measure the melt motion rate. The results obtained emphasize the significance of TCC in the process of single crystal growth under terrestrial conditions.

  10. Viscosity Measurement for Tellurium Melt

    Science.gov (United States)

    Lin, Bochuan; Li, Chao; Ban, Heng; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2006-01-01

    The viscosity of high temperature Te melt was measured using a new technique in which a rotating magnetic field was applied to the melt sealed in a suspended ampoule, and the torque exerted by rotating melt flow on the ampoule wall was measured. Governing equations for the coupled melt flow and ampoule torsional oscillation were solved, and the viscosity was extracted from the experimental data by numerical fitting. The computational result showed good agreement with experimental data. The melt velocity transient initiated by the rotating magnetic field reached a stable condition quickly, allowing the viscosity and electrical conductivity of the melt to be determined in a short period.

  11. Hydrological scenarios for two selected Alpine catchments for the 21st century using a stochastic weather generator and enhanced process understanding for modelling of seasonal snow and glacier melt for improved water resources management

    Science.gov (United States)

    Strasser, Ulrich; Schneeberger, Klaus; Dabhi, Hetal; Dubrovsky, Martin; Hanzer, Florian; Marke, Thomas; Oberguggenberger, Michael; Rössler, Ole; Schmieder, Jan; Rotach, Mathias; Stötter, Johann; Weingartner, Rolf

    2016-04-01

    The overall objective of HydroGeM³ is to quantify and assess both water demand and water supply in two coupled human-environment mountain systems, i.e. Lütschine in Switzerland and Ötztaler Ache in Austria. Special emphasis is laid on the analysis of possible future seasonal water scarcity. The hydrological response of high Alpine catchments is characterised by a strong seasonal variability with low runoff in winter and high runoff in spring and summer. Climate change is expected to cause a seasonal shift of the runoff regime and thus it has significant impact on both amount and timing of the release of the available water resources, and thereof, possible future water conflicts. In order to identify and quantify the contribution of snow and ice melt as well as rain to runoff, streamflow composition will be analysed with natural tracers. The results of the field investigations will help to improve the snow and ice melt and runoff modules of two selected hydrological models (i.e. AMUNDSEN and WaSiM) which are used to investigate the seasonal water availability under current and future climate conditions. Together, they comprise improved descriptions of boundary layer and surface melt processes (AMUNDSEN), and of streamflow runoff generation (WaSiM). Future meteorological forcing for the modelling until the end of the century will be provided by both a stochastic multi-site weather generator, and downscaled climate model output. Both approches will use EUROCORDEX data as input. The water demand in the selected study areas is quantified for the relevant societal sectors, e.g. agriculture, hydropower generation and (winter) tourism. The comparison of water availability and water demand under current and future climate conditions will allow the identification of possible seasonal bottlenecks of future water supply and resulting conflicts. Thus these investigations can provide a quantitative basis for the development of strategies for sustainable water management in

  12. MELT-IIIB: an updated version of the melt code

    International Nuclear Information System (INIS)

    Tabb, K.K.; Lewis, C.H.; O'Dell, L.D.; Padilla, A. Jr.; Smith, D.E.; Wilburn, N.P.

    1979-04-01

    The MELT series is a reactor modeling code designed to investigate a wide variety of hypothetical accident conditions, particularly the transient overpower sequence. MELT-IIIB is the latest in the series

  13. What olivine and clinopyroxene mineral chemistry and melt inclusion study can tell us about magmatic processes in a post-collisional setting. Examples from the Miocene-Quaternary East Carpathian volcanic chain, Romania

    Science.gov (United States)

    Seghedi, Ioan; Mason, Paul R. D.

    2015-04-01

    Calc-alkaline magmatism occurred along the easternmost margin of Tisia-Dacia at the contact with East European Platform forming the Călimani-Gurghiu- Harghita volcanic chain. Its northern part represented by Călimani-Gurghiu-North Harghita (CGNH hereafter) is showing a diminishing age and volume southwards at 10-3.9 Ma. This marks the end of subduction-related magmatism along the post-collision front of the European convergent plate margin. Magma generation was associated with progressive break-off of a subducted slab and asthenosphere uprise. Fractionation and crustal assimilation were typical CGNH volcanic chain. The rocks show homogeneous 87Sr/86Sr, but a linear trend of Th/Y vs Nb/Y that reflects a common mantle source considered to be the metasomatized lithospheric mantle wedge. Fractionation and/or assimilation-fractional crystallization are characteristic for each main volcanic area, suggestive of lower to middle crust magma chamber processes. The South Harghita (SH) volcanic area represents direct continuation of the CGNH volcanic chain. Here at ca. 3 Ma following a time-gap, magma compositions changed to adakite-like calc-alkaline and continued until recent times (< 0.03 Ma). This volcanism was interrupted at ~1.6-1.8 Ma by simultaneous generation of Na- and K-alkalic varieties in nearby areas, suggestive of various sources and melting mechanisms, closely related to the hanging block beneath Vrancea seismic zone. The specific geochemistry is revealed by higher Nb/Y and Th/Y ratios and lower 87Sr/86Sr as compared to the CGNH chain. Identification of primitive magmas has been difficult despite the fact that this volcanic area contains more basalts than any other in the Carpathian-Pannonian region. Since the most primitive rocks represent the best opportunity to identify the trace element composition of the mantle source beneath the East Carpathian volcanic chain we use mineral and melt inclusions in olivine and composition of the most primitive

  14. Melting tests for recycling of radioactive metal wastes

    International Nuclear Information System (INIS)

    Nakamura, Hisashi; Kanazawa, Katsuo; Fujiki, Kazuo

    1995-01-01

    To allow the future recycling of decommissioning wastes to promote smoothly, melting tests were conducted using metal wastes and simulated wastes with radioisotopes. The test results indicate that the transfer behavior of radionuclides during melting is basically understood by considering the volatility and oxidizable tendency of each radionuclide. The partitioning of some radionuclides into products was influenced by the melting process of wastes. The radioactivity distribution in ingots was uniform regardless of the kinds of radionuclide. (author)

  15. Melting of peridotite to 140 gigapascals.

    Science.gov (United States)

    Fiquet, G; Auzende, A L; Siebert, J; Corgne, A; Bureau, H; Ozawa, H; Garbarino, G

    2010-09-17

    Interrogating physical processes that occur within the lowermost mantle is a key to understanding Earth's evolution and present-day inner composition. Among such processes, partial melting has been proposed to explain mantle regions with ultralow seismic velocities near the core-mantle boundary, but experimental validation at the appropriate temperature and pressure regimes remains challenging. Using laser-heated diamond anvil cells, we constructed the solidus curve of a natural fertile peridotite between 36 and 140 gigapascals. Melting at core-mantle boundary pressures occurs at 4180 ± 150 kelvin, which is a value that matches estimated mantle geotherms. Molten regions may therefore exist at the base of the present-day mantle. Melting phase relations and element partitioning data also show that these liquids could host many incompatible elements at the base of the mantle.

  16. Melt spun aluminium alloys for moulding optics

    Science.gov (United States)

    Gubbels, G.; Tegelaers, L.; Senden, R.

    2013-09-01

    Melt spinning is a rapid quenching process that makes it possible to create materials with a very fine microstructure. Due to this very fine microstructure the melt spinning process is an enabler for diamond turning optics and moulds without the need of post-polishing. Using diamond turning of melt spun aluminium one can achieve coating concept RSA-905 can be upgraded to a competitive alternative to steel in terms of price, performance and logistics. This paper presents some recent developments for improved mould performance of such concept. Hardness, wear resistance and adhesion are topics of interest and they can be applied by special coatings such as diamond-like carbon (DLC) and chromium nitride (CrN). These coatings make the aluminium alloy suitable for moulding mass production of small as well as larger optics, such as spectacle lenses.

  17. Chemical decontamination and melt densification

    International Nuclear Information System (INIS)

    Dillon, R.L.; Griggs, B.; Kemper, R.S.; Nelson, R.G.

    1976-01-01

    Preliminary studies on the chemical decontamination and densification of Zircaloy, stainless steel, and Inconel undissolved residues remaining after dissolution of the UO 2 --PuO 2 spent fuel material from sheared fuel bundles are reported. The studies were made on cold or very small samples to demonstrate the feasibility of the processes developed before proceeding to hot cell demonstrations with kg level of the sources. A promising aqueous decontamination method for Zr alloy cladding was developed in which oxidized surfaces are conditioned with HF prior to leaching with ammonium oxalate, ammonium citrate, ammonium fluoride, and hydrogen peroxide. Feasibility of molten salt decontamination of oxidized Zircaloy was demonstrated. A low melting alloy of Zircaloy, stainless steel, and Inconel was obtained in induction heated graphite crucibles. Segregated Zircaloy cladding sections were directly melted by the inductoslag process to yield a metal ingot suitable for storage. Both Zircaloy and Zircaloy--stainless steel--Inconel alloys proved to be highly satisfactory getters and sinks for recovered tritium

  18. FY 1998 annual report on the study on solidification process of hot, heat-resistant metal melts; 1998 nendo tainetsu kinzoku koon yueki no gyoko katei no kenkyu chosa hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    Described herein are results of the studies on basic aspects of solidification process of hot, heat-resistant metal melts under a microgravity atmosphere, its applicability to industrial purposes, production of new metallic structures by precision casting and supercooling solidification of the heat-resistant, metal alloy parts, and evaluation techniques therefor. In the supercooling solidification of Al, its purity greatly determines the crystal morphology. The single crystal can be produced under a microgravity when it is 99.9% pure. The supercooling solidification under a microgravity can give an Al-Pb alloy structure of uniform dendrite structure both on the surface and inside, free of gravity-caused segregation of Pb. The welding problems caused by Al{sub 2}O{sub 3} present in the Al are solved. The study also clarifies the effects of the microgravity atmosphere in the spot welding by a pulsed YAG laser on, e.g., melting characteristics, welding phenomena and formation of welding defects. The basic knowledge obtained is expected to contribute to, e.g., precision casting and welding of heat-resistant alloys, and creation of new alloys. (NEDO)

  19. Melt electrospinning of biodegradable polyurethane scaffolds.

    Science.gov (United States)

    Karchin, Ari; Simonovsky, Felix I; Ratner, Buddy D; Sanders, Joan E

    2011-09-01

    Electrospinning from a melt, in contrast to from a solution, is an attractive tissue engineering scaffold manufacturing process as it allows for the formation of small diameter fibers while eliminating potentially cytotoxic solvents. Despite this, there is a dearth of literature on scaffold formation via melt electrospinning. This is likely due to the technical challenges related to the need for a well-controlled high-temperature setup and the difficulty in developing an appropriate polymer. In this paper, a biodegradable and thermally stable polyurethane (PU) is described specifically for use in melt electrospinning. Polymer formulations of aliphatic PUs based on (CH(2))(4)-content diisocyanates, polycaprolactone (PCL), 1,4-butanediamine and 1,4-butanediol (BD) were evaluated for utility in the melt electrospinning process. The final polymer formulation, a catalyst-purified PU based on 1,4-butane diisocyanate, PCL and BD in a 4/1/3M ratio with a weight-average molecular weight of about 40kDa, yielded a nontoxic polymer that could be readily electrospun from the melt. Scaffolds electrospun from this polymer contained point bonds between fibers and mechanical properties analogous to many in vivo soft tissues. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  20. Laser-based microbonding using hot melt adhesives

    Science.gov (United States)

    Hemken, G.; Böhm, S.

    2009-02-01

    This paper presents an alternative adhesive bonding system which is able to join very small parts as well as relatively large parts with high accuracy requirements. The main advantages are the possibility to apply small volumes, to preapply the adhesive with a temporarily delayed joining procedure and extremely short set cycles. The center of micro joining develops suitable joining techniques on the basis of non-viscous adhesive systems (hot melts). The process development focuses on the suitability for automation, process times and the applicability of batch processes. The article discusses certain hot melt application techniques that are suitable for batch production e. g. the laser-sintering of hot melt powder, presents an adapted assembly system and shows an example of an automated assembly process for hot melt coated micro components. Therefore, using hot melts can be a technologically and economically interesting alternative for the assembly and packaging of MEMS.

  1. Crystallization, recrystallization, and melting lines in syndiotactic polypropylene crystallized from quiescent melt and semicrystalline state due to stress-induced localized melting and recrystallization.

    Science.gov (United States)

    Lu, Ying; Wang, Yaotao; Fu, Lianlian; Jiang, Zhiyong; Men, Yongfeng

    2014-11-13

    Crystalline lamellar thickness in syndiotactic polypropylene (sPP) during crystallization from either isothermal molten or stretching induced localized melt states and during subsequent heating was investigated by means of temperature dependent small-angle X-ray scattering techniques. Well-defined crystallization lines where the reciprocal lamellar thickness is linearly dependent on crystallization temperature were observed. Unlike in the case of polybutene-1 where stretching crystallization line was shifted to direction of much smaller lamellar thickness (Macromolecules 2013, 46, 7874), the stretching induced crystallization line for sPP deviates from its corresponding isothermal crystallization line only slightly. Such phenomenon could be attributed to the fact that both crystallization processes from quiescent melt and stress induced localized melt are mediated in a mesomorphic phase in sPP. Subsequent heating of sPP after crystallization revealed the same melting behavior in both systems for the two kinds of crystallites obtained from either quiescent melt or stretching induced localized melt. Both of them underwent melting and recrystallization when the lamellar thickness was smaller than a critical value and melting directly without changing in thickness when the lamellar thickness was larger than the critical value. The melting behavior in sPP systems can be understood by considering the chain relaxation ability within crystalline phase and also can be used as evidence that the crystallization from molten state and stress-induced crystallization passed through the intermediate phase before forming crystallites.

  2. Effect of fluoride content on ion release from cast and selective laser melting-processed Co-Cr-Mo alloys.

    Science.gov (United States)

    Yang, Xu; Xiang, Nan; Wei, Bin

    2014-11-01

    Selective laser melting (SLM) alloy is gaining popularity in prosthetic dentistry. However, its biocompatibility has been of some concern because of long-term exposure to fluoride in the oral environment. The purpose of this study was to examine the effect of fluoride concentration on ion release from Co-Cr-Mo alloy specimens fabricated using either SLM or lost-wax casting when immersed in an artificial saliva solution containing fluoride. Specimens were prepared with either a SLM system for the SLM alloy or conventional lost-wax techniques for the cast alloy. The specimen surfaces were wet ground with silicon carbide paper (400, 800, and 1200 grit) and immersed in modified artificial saliva solutions, the pH of which had been adjusted to 5.0 with lactic acid and which contained NaF at concentrations of 0.00%, 0.05%, 0.1%, or 0.2%. The metal ion content of the solution was determined with an inductively coupled plasma mass spectrometer. The results were submitted to 2-way ANOVA and regression analysis (α=.05). Fluoride concentration significantly influenced the elemental ion release from both the SLM and cast alloys. The quantity of ions released increased significantly with increasing fluoride concentration. The ion release from the cast specimens was significantly greater than that from the SLM specimens. The performance of the SLM alloy in immersion tests demonstrates that this new technique is a superior choice because of its good biocompatibility. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  3. Melting graft wound syndrome

    Directory of Open Access Journals (Sweden)

    Shiou-Mei Chen

    2017-09-01

    Full Text Available Melting graft wound syndrome is characterized by progressive epidermal loss from a previously well-taken skin graft, healed burn, or donor site. It may result in considerable morbidity and require prolonged treatment. We report a 23-year-old flame-burned patient with second- to third-degree burns involving more than 70% of the total body surface area, whose condition was complicated with septic shock. The patient presented with erosions and ulcers occurring on previously well-taken skin graft recipient sites over both legs and progressive epidermal loss on donor sites over the back. The patient's presentation was compatible with the diagnosis of melting graft wound syndrome, and we successfully treated the patient with debridement and supportive treatment.

  4. Influence of treatments using different magnesium ferroalloys on the melt quality and the solidification processes of ductile irons; Influencia de los tratamientos realizados con diferentes ferroaleaciones de magnesio en la evolucion de la calidad metalurgica y los procesos de solidificacion de las funciones esferoidales

    Energy Technology Data Exchange (ETDEWEB)

    Loizaga, A.; Sertucha, J.; Suarez, R.

    2008-07-01

    In this work the metallurgical consequences of treatments applied on ductile irons using ferroalloys with different magnesium contents are analysed. The solidification processes have an important influence on the mechanical properties and the functionality of the iron castings along their service period. Consequently, the comparison of the characterstics of the cooling curves recorded from the melt and the active oxygen and sulphur contents have been used for quantifying the effects of treatments performed utilizing different types of commercial FeSiMg. The addition of magnesium into the melt strongly removes sulphur and oxygen contents and important degradations of the metallurgical quality are finally obtained as a consequence of them. On the other hand, the composition of the resulting slags and the evolution of the melt characteristics as a function of the remaining time into the pouring device is investigated. The magnesium content in ferroalloys becomes a critical parameters in the evolution of the melt quality of treated irons. (Author) 18 refs.

  5. Introduction of Electrostatically Charged Particles into Metal Melts

    Science.gov (United States)

    Kudryashova, Olga; Vorozhtsov, Sergey; Stepkina, Maria; Khrustalev, Anton

    2017-12-01

    One of the possible methods to produce composite alloys with improved mechanical characteristics is the modification of metal melts using submicron- or nanosized particles. Different methods, like ultrasonic or vibration processing, have been used to introduce these particles into the metal melt. The introduction of particles into a metal melt is prevented by the poor wettability of the liquid metal. The present study explores the use of electrostatic charge for increasing the wettability of the particles and preventing their agglomeration. The wettability of electrostatically charged particles by the metal melt under the impact of ultrasound has been studied. The relationships between the impact time and the physical and chemical properties of the particles and the melt along with the characteristics of the acoustic radiation have been studied. It was experimentally demonstrated that the introduction of electrostatically charged particles into the metal melt reduces the porosity and the crystal grain size.

  6. Reaction between YBCO/Ag superconductor and melted silver

    International Nuclear Information System (INIS)

    Maeda, Junya; Izumi, Teruo; Shiohara, Yuh

    1999-01-01

    In order to study the feasibility of applying liquid phase processing using melted silver to fabricate YBCO/silver contacts, the chemical reaction at the boundaries between the Y-Ba-Cu-O (YBCO) superconducting matrix and melted silver was observed. YBCO superconducting current leads prepared by the unidirectional solidification method were dipped into liquid silver melted by an electric furnace. Copper-poor layers were formed at the boundary between the YBCO matrix and melted silver, although the temperatures were lower than the YBCO/Ag melting temperature (∼970 deg. C). It was considered that melted silver took up copper from the YBa 2 Cu 3 O x (Y123) crystal, and it is considered that the phase equilibrium at the boundary between the YBCO matrix and molten silver was changed from Y 2 Ba 1 Cu 1 O 5 (Y211)-Y123 to another phase. (author)

  7. Investigation of the core melt accident in light water reactors

    International Nuclear Information System (INIS)

    Koerber, H.

    1980-01-01

    In the thesis the core melt accident, heating up and collapsing of the reactor core were investigated. The most important parameters of influence were found and their effect on the development of the accident were shown. A causal diagram was developed representing the great number of events occurring in the course of the core melt accident as well as their mutual dependences. Models were developed and applied for a detailed description of the collapse process, melting of materials, heat and material transport at flow-off of the melted mass and for taking into account steam blocking in the destroyed core sections. (orig.) [de

  8. Vacuum induction melting of uranium ingots

    International Nuclear Information System (INIS)

    Hussain, M.M.; Bagchi, S.N.; Singh, S.P.

    1992-01-01

    Massive uranium ingot is produced from green salt (UF 4 ) using calciothermic reduction (CTR) or magnesiothermic reduction (MTR) process. CTR process has been replaced by MTR process at Trombay due to economic considerations. This paper highlights problems associated with the vacuum induction melting of MTR ingots and the remedial measures taken to produce good quality billets. Details of metallographic examination of inclusions in ingots and billets have been incorporated. (author). 3 figs

  9. A melt evolution model for Kerimasi volcano, Tanzania: Evidence from carbonate melt inclusions in jacupirangite

    Science.gov (United States)

    Káldos, Réka; Guzmics, Tibor; Mitchell, Roger H.; Dawson, John Barry; Milke, Ralf; Szabó, Csaba

    2015-12-01

    This study presents compositional data for a statistically significant number (n = 180) of heated and quenched (recreated) carbonate melt inclusions trapped in magnetite and clinopyroxene in jacupirangite from Kerimasi volcano (Tanzania). On the basis of homogenization experiments for clinopyroxene-hosted melt inclusions and forsterite-monticellite-calcite phase relations, a range of 1000 to 900 °C is estimated for their crystallization temperatures. Petrographic observations and geochemical data show that during jacupirangite crystallization, a CaO-rich and alkali-"poor" carbonate melt (relative to Oldoinyo Lengai natrocarbonatite) existed and was entrapped in the precipitating magnetite, forming primary melt inclusions, and was also enclosed in previously crystallized clinopyroxene as secondary melt inclusions. The composition of the trapped carbonate melts in magnetite and clinopyroxene is very similar to the parental melt of Kerimasi calciocarbonatite; i.e., enriched in Na2O, K2O, F, Cl and S, but depleted in SiO2 and P2O5 relative to carbonate melts entrapped at an earlier stage and higher temperature (1050-1100 °C) during the formation of Kerimasi afrikandite. Significant compositional variation is shown by the major minerals of Kerimasi plutonic rocks (afrikandite, jacupirangite and calciocarbonatite). Magnetite and clinopyroxene in the jacupirangite are typically transitional in composition between those of afrikandite and calciocarbonatite. These data suggest that the jacupirangite represents an intermediate stage between the formation of afrikandite and calciocarbonatite. Jacupirangite most probably formed when immiscible silicate and carbonate melts separated from the afrikandite body, although the carbonate melt was not separated completely from the silicate melt fraction. In general, during the evolution of the carbonate melt at Kerimasi, concentrations of P2O5 and SiO2 decreased, whereas volatile content (alkalis, S, F, Cl and H2O) increased

  10. Numerical Study Of Melted Particles Crush Metallic Substrates And The Interaction Between Particles And A Plasma Beam In The Thermal Projection Process

    International Nuclear Information System (INIS)

    Kriba, Ilhem; Djebaili, A.

    2008-01-01

    Plasma spray processes have been widely used to produce high performance coatings of a wide range of Materials (metallic, non-metallic, ceramics), offering protection from, eg. wear, extreme temperature, chemical attack and environmental corrosion. To obtain good quality coatings, spray parameters must be carefully selected. Due to the large variety in process parameters, it is difficult to optimize the process for each specific coating and substrate combinations. Furthermore modelling the spray process allows a better understanding of the process sequences during thermal spraying. Good agreement of the virtual spraying process with the real coating formation is achieved by modelling the particular process steps. The simulation of coating formation to estimate the process parameters is an important tool to develop new coating structures with defined properties. In this work, the process of plasma sprayed coating has been analyzed by numerical simulation. Commercial code is used to predict the plasma jet characteristics, plasma--particle interaction, and coating formation. Using this model we can obtain coating microstructure and characteristics which form a foundation for further improvement of an advanced ceramic coating build up model.

  11. Effect of stirring on striae in glass melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Yue, Yuanzheng

    2012-01-01

    Chemical striae have often negative effect on the glass properties, and hence, elimination of striae has been a key issue in glass science and technology. To produce highly homogeneous glasses, it is necessary to stir melts during the melting process. To explore the physical origin of the stria...

  12. Incorporation of Certain Hydrophobic Excipients in the Core of Melt ...

    African Journals Online (AJOL)

    Purpose: A process of melt granulation whereby the drug powder is mixed with a melted wax has been used to modify the dissolution rates of drug particles. The present study investigated how the incorporation of hydrophobic materials (talc or magnesium stearate) in the core of such granules may further retard drug ...

  13. Incorporation of Certain Hydrophobic Excipients in the Core of Melt ...

    African Journals Online (AJOL)

    Patrick Erah

    Objective - A process of melt granulation whereby the drug powder is mixed with a melted wax has been used to modify the dissolution rates of drug particles. The present study investigated how the incorporation of hydrophobic materials (talc or magnesium stearate) in the core of such granules may further retard drug ...

  14. Single scan vector prediction in selective laser melting

    NARCIS (Netherlands)

    Wits, Wessel Willems; Bruins, R.; Terpstra, L.; Huls, R.A.; Geijselaers, Hubertus J.M.

    2015-01-01

    In selective laser melting (SLM) products are built by melting layers of metal powder successively. Optimal process parameters are usually obtained by scanning single vectors and subsequently determining which settings lead to a good compromise between product density and build speed. This paper

  15. Fatigue behavior and microstructural characterization of nickel-base superalloy Inconel 939 produced by laser melting process; Ermuedungsverhalten und mikrostrukturelle Charakterisierung der im Laserschmelzverfahren hergestellten Nickelbasis-Superlegierung Inconel 939

    Energy Technology Data Exchange (ETDEWEB)

    Kanagarajah, Pirabagini

    2016-07-01

    The present study investigated the microstructural characteristics and its impact on the resulting mechanical properties of the nickel-based superalloy lnconel 939 processed by selective laser melting (SLM) and data are compared to an lnconel 939 cast alloy. The monotonic and microstructural results demonstrate a strong dependency on the building direction of the SLM-processed material and a distinct difference to the cast alloy, particularly relating to the microstructure. Strain-controlled isothermal and thermomechanical fatigue in combination with the digital-imagecorrelation (DIC) describe the mechanical behavior and the critical area in the structure. Whether the SLM- or the cast alloy achieves a higher lifetime during isothermal fatigue, depends on the strain amplitude. For low strain amplitudes, the aged SLM-material has a higher lifetime in the temperature range from room temperature to 750 C and shows a better fatigue characteristic compared to the cast alloy. By increasing the amplitude, the existing pores become dominant and a fast failure occurs. However, the porosity was reduced drastically in the HIP-condition. [German] In der vorliegenden Arbeit wurden die mikrostrukturellen Eigenschaften und das dadurch resultierende mechanische Verhalten der im SLM-Verfahren (Selective Laser Melting) hergestellten Nickelbasis-Superlegierung Inconel 939 untersucht und einer Inconel 939 Gusslegierung gegenuebergestellt. Die monotonen und mikrostrukturellen Untersuchungsergebnisse zeigen eine eindeutige Abhaengigkeit der Herstellungsrichtung und deutliche Unterschiede zur Gusslegierung, insbesondere in der Mikrostruktur. Dehnungsgeregelte isotherme und thermomechanische Ermuedungsversuche in Kombination mit der Methode der digitalen Bildkorrelation (DIC) beschreiben das mechanische Verhalten sowie die kritischen Bereiche im Gefuege. Ob beim SLM- oder Gusswerkstoff eine hoehere Lebensdauer bei der isothermen Ermuedung erreicht wird, ist von der Hoehe der Beanspruchung

  16. Hot-melt extrusion--basic principles and pharmaceutical applications.

    Science.gov (United States)

    Lang, Bo; McGinity, James W; Williams, Robert O

    2014-09-01

    Originally adapted from the plastics industry, the use of hot-melt extrusion has gained favor in drug delivery applications both in academia and the pharmaceutical industry. Several commercial products made by hot-melt extrusion have been approved by the FDA, demonstrating its commercial feasibility for pharmaceutical processing. A significant number of research articles have reported on advances made regarding the pharmaceutical applications of the hot-melt extrusion processing; however, only limited articles have been focused on general principles regarding formulation and process development. This review provides an in-depth analysis and discussion of the formulation and processing aspects of hot-melt extrusion. The impact of physicochemical properties of drug substances and excipients on formulation development using a hot-melt extrusion process is discussed from a material science point of view. Hot-melt extrusion process development, scale-up, and the interplay of formulation and process attributes are also discussed. Finally, recent applications of hot-melt extrusion to a variety of dosage forms and drug substances have also been addressed.

  17. Numerical study of melted particles crush metallic substrates and the interaction between particles and a plasma beam in the thermal projection process

    International Nuclear Information System (INIS)

    Kriba, Ilhem; Djebaili, A.

    2009-01-01

    Plasma spray processes have been widely used to produce high performance coatings of a wide range of materials (metallic, non-metallic, and ceramics), offering protection from, e.g. wear, extreme temperature, chemical attack and environmental corrosion. To obtain good quality coatings, spray parameters must be carefully selected. Due to the large variety in process parameters, it is difficult to optimize the process for each specific coating and substrate combinations. Furthermore modelling the spray process allows a better understanding of the process sequences during thermal spraying. The simulation of coating formation to estimate the process parameters is an important tool to develop new coating structures with defined properties. In this work, the process of plasma sprayed coating has been analyzed by numerical simulation. Commercial code is used to predict the plasma jet characteristics, plasma-particle interaction, and coating formation. Using this model we can obtain coating microstructure and characteristics which form a foundation for further improvement of an advanced ceramic coating build up model

  18. Numerical study of melted particles crush metallic substrates and the interaction between particles and a plasma beam in the thermal projection process

    Energy Technology Data Exchange (ETDEWEB)

    Kriba, Ilhem [Plasma Laboratory, Faculty of Sciences, Department of Physics, University of Ouargla, Ouargla (Algeria)], E-mail: ilhem_kriba@yahoo.fr; Djebaili, A. [Laboratory of Chemistry and Environment Chemistry L.C.C.E, University of Batna (Algeria)

    2009-03-01

    Plasma spray processes have been widely used to produce high performance coatings of a wide range of materials (metallic, non-metallic, and ceramics), offering protection from, e.g. wear, extreme temperature, chemical attack and environmental corrosion. To obtain good quality coatings, spray parameters must be carefully selected. Due to the large variety in process parameters, it is difficult to optimize the process for each specific coating and substrate combinations. Furthermore modelling the spray process allows a better understanding of the process sequences during thermal spraying. The simulation of coating formation to estimate the process parameters is an important tool to develop new coating structures with defined properties. In this work, the process of plasma sprayed coating has been analyzed by numerical simulation. Commercial code is used to predict the plasma jet characteristics, plasma-particle interaction, and coating formation. Using this model we can obtain coating microstructure and characteristics which form a foundation for further improvement of an advanced ceramic coating build up model.

  19. Characterisation and modelling of the thermorheological properties of pharmaceutical polymers and their blends using capillary rheometry: Implications for hot melt processing of dosage forms.

    Science.gov (United States)

    Jones, David S; Margetson, Daniel N; McAllister, Mark S; Andrews, Gavin P

    2015-09-30

    Given the growing interest in thermal processing methods, this study describes the use of an advanced rheological technique, capillary rheometry, to accurately determine the thermorheological properties of two pharmaceutical polymers, Eudragit E100 (E100) and hydroxypropylcellulose JF (HPC) and their blends, both in the presence and absence of a model therapeutic agent (quinine, as the base and hydrochloride salt). Furthermore, the glass transition temperatures (Tg) of the cooled extrudates produced using capillary rheometry were characterised using Dynamic Mechanical Thermal Analysis (DMTA) thereby enabling correlations to be drawn between the information derived from capillary rheometry and the glass transition properties of the extrudates. The shear viscosities of E100 and HPC (and their blends) decreased as functions of increasing temperature and shear rates, with the shear viscosity of E100 being significantly greater than that of HPC at all temperatures and shear rates. All platforms were readily processed at shear rates relevant to extrusion (approximately 200-300 s(-1)) and injection moulding (approximately 900 s(-1)). Quinine base was observed to lower the shear viscosities of E100 and E100/HPC blends during processing and the Tg of extrudates, indicative of plasticisation at processing temperatures and when cooled (i.e. in the solid state). Quinine hydrochloride (20% w/w) increased the shear viscosities of E100 and HPC and their blends during processing and did not affect the Tg of the parent polymer. However, the shear viscosities of these systems were not prohibitive to processing at shear rates relevant to extrusion and injection moulding. As the ratio of E100:HPC increased within the polymer blends the effects of quinine base on the lowering of both shear viscosity and Tg of the polymer blends increased, reflecting the greater solubility of quinine within E100. In conclusion, this study has highlighted the importance of capillary rheometry in

  20. Mechanical properties of melt-derived erbium oxide

    International Nuclear Information System (INIS)

    Neuman, A.D.; Blacic, M.J.; Platero, M.; Romero, R.S.; McClellan, K.J.; Petrovic, J.J.

    1998-01-01

    Erbium oxide (Er 2 O 3 ) is a rare earth oxide that is chemically and thermally stable and has a melting point of 2,430 C. There is relatively little information available regarding single crystal growth of erbia or the properties of erbia. In this study, erbia single crystals have been grown in a Xenon Optical Floating Zone Unit (XeOFZ) capable of melting materials at temperatures up to 3,000 C. Erbia was melt synthesized in the XeOFZ unit in a container less fashion, proving for little chance of contamination. Crystals were grown in compressed air and in reducing atmospheres. A recurring problem with melt synthesis of erbia is the appearance of flakes at the edges of the melt zone during growth; these flakes disrupt the growth process. The processing details and an initial survey of the physical properties of erbia single crystals is discussed

  1. The influence of partial melting and melt migration on the rheology of the continental crust

    Science.gov (United States)

    Cavalcante, Geane Carolina G.; Viegas, Gustavo; Archanjo, Carlos José; da Silva, Marcos Egydio

    2016-11-01

    The presence of melt during deformation produces a drastic change in the rheological behavior of the continental crust; rock strength is decreased even for melt fractions as low as ∼7%. At pressure/temperature conditions typical of the middle to lower crust, melt-bearing systems may play a critical role in the process of strain localization and in the overall strength of the continental lithosphere. In this contribution we focus on the role and dynamics of melt flow in two different mid-crustal settings formed during the Brasiliano orogeny: (i) a large-scale anatectic layer in an orthogonal collision belt, represented by the Carlos Chagas anatexite in southeastern Brazil, and (ii) a strike-slip setting, in which the Espinho Branco anatexite in the Patos shear zone (northeast Brazil) serves as an analogue. Both settings, located in eastern Brazil, are part of the Neoproterozoic tectonics that resulted in widespread partial melting, shear zone development and the exhumation of middle to lower crustal layers. These layers consist of compositionally heterogeneous anatexites, with variable former melt fractions and leucosome structures. The leucosomes usually form thick interconnected networks of magma that reflect a high melt content (>30%) during deformation. From a comparison of previous work based on detailed petrostructural and AMS studies of the anatexites exposed in these areas, we discuss the rheological implications caused by the accumulation of a large volume of melt ;trapped; in mid-crustal levels, and by the efficient melt extraction along steep shear zones. Our analyses suggest that rocks undergoing partial melting along shear settings exhibit layers with contrasting competence, implying successive periods of weakening and strengthening. In contrast, regions where a large amount of magma accumulates lack clear evidence of competence contrast between layers, indicating that they experienced only one major stage of dramatic strength drop. This comparative

  2. Elastic properties of silicate melts

    DEFF Research Database (Denmark)

    Clark, Alisha N.; Lesher, Charles E.

    2017-01-01

    Low seismic velocity regions in the mantle and crust are commonly attributed to the presence of silicate melts. Determining melt volume and geometric distribution is fundamental to understanding planetary dynamics. We present a new model for seismic velocity reductions that accounts for the anoma......Low seismic velocity regions in the mantle and crust are commonly attributed to the presence of silicate melts. Determining melt volume and geometric distribution is fundamental to understanding planetary dynamics. We present a new model for seismic velocity reductions that accounts...... for the anomalous compressibility of silicate melt, rendering compressional wave velocities more sensitive to melt fraction and distribution than previous estimates. Forward modeling predicts comparable velocity reductions for compressional and shear waves for partially molten mantle, and for low velocity regions...

  3. Model of the process with piecewise-constant extremals to minimize losses of vitamins during the melting of melons and gourds

    Directory of Open Access Journals (Sweden)

    E. V. Inochkina

    2017-01-01

    Full Text Available The extension of periods of storage of fruits of gourds is an urgent task processing industry. The most developed and available for injection is a method of dehydration of raw materials due to supply of heat transfer fluids. In addition to solid dry frame in raw materials is 80–90% water. In the period of moisture removal from raw material changes of thermal-physical and structural-mechanical and physicochemical characteristics. The ratio of water and dry matter in vegetative raw materials largely determines the modes of drying and storage conditions of the finished product. During drying, there are a number of limitations: the drying temperature should not exceed the degradation temperature of vitamins and proteins, and the magnitude of course, the moisture content of the product depends on the reaction prevention malonodinitrile sugars at the critical moisture content. An important problem of the drying of production is quality control stages of drying, the dynamics of which is quite difficult to describe using mathematical models. The main factors of optimization of industrial drying processes is preservation of valuable components of the feedstock, the drying time, energy and resource conservation. Development of effective control algorithm for the process of dehydration of raw materials described in the article on the example of drying of slices of melon. Experimental approach a two-stage process of drying of melon varieties Taman, the proposed regression model with the relaxation-based on humidity and content of vitamin C from the variable in time temperature and pressure, based on the available literature and own experimental data. According to the optimal control of the drying process to search for the thermobaric regime that maximizes the vitamin C content at the end of the drying, under specified conditions, the humidity. The main findings are the solution of the problem for the case of piecewise constant temperature and pressure in

  4. Global approach for the validation of an in-line Raman spectroscopic method to determine the API content in real-time during a hot-melt extrusion process.

    Science.gov (United States)

    Netchacovitch, L; Thiry, J; De Bleye, C; Dumont, E; Cailletaud, J; Sacré, P-Y; Evrard, B; Hubert, Ph; Ziemons, E

    2017-08-15

    Since the Food and Drug Administration (FDA) published a guidance based on the Process Analytical Technology (PAT) approach, real-time analyses during manufacturing processes are in real expansion. In this study, in-line Raman spectroscopic analyses were performed during a Hot-Melt Extrusion (HME) process to determine the Active Pharmaceutical Ingredient (API) content in real-time. The method was validated based on a univariate and a multivariate approach and the analytical performances of the obtained models were compared. Moreover, on one hand, in-line data were correlated with the real API concentration present in the sample quantified by a previously validated off-line confocal Raman microspectroscopic method. On the other hand, in-line data were also treated in function of the concentration based on the weighing of the components in the prepared mixture. The importance of developing quantitative methods based on the use of a reference method was thus highlighted. The method was validated according to the total error approach fixing the acceptance limits at ±15% and the α risk at ±5%. This method reaches the requirements of the European Pharmacopeia norms for the uniformity of content of single-dose preparations. The validation proves that future results will be in the acceptance limits with a previously defined probability. Finally, the in-line validated method was compared with the off-line one to demonstrate its ability to be used in routine analyses. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Conditioning of nuclear cladding wastes by melting

    International Nuclear Information System (INIS)

    Puyou, M.; Jouan, A.; Jacquet-Francillon, N.

    1991-01-01

    This paper discusses a cold-crucible induction melting process to condition cladding waste from irradiated fast breeder reactor fuel. The process has been developed by the CEA at Marcoule (France) as part of a major R and D program. It has been qualified at industrial scale on nonradioactive waste, and at laboratory scale on radioactive waste: several radioactive ingots have been produced from actual stainless steel or zircaloy hulls. The results confirm the numerous advantages of this containment method

  6. Thermodynamics of freezing and melting

    OpenAIRE

    Pedersen, Ulf Rørbæk; Costigliola, Lorenzo; Bailey, Nicholas; Schrøder, Thomas; Dyre, Jeppe C.

    2016-01-01

    Although the freezing of liquids and melting of crystals are fundamental for many areas of the sciences, even simple properties like the temperature?pressure relation along the melting line cannot be predicted today. Here we present a theory in which properties of the coexisting crystal and liquid phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variatio...

  7. Constraints on melt migration in the Earth's upper mantle

    Science.gov (United States)

    Garapic, Gordana

    Melting and melt segregation are key processes in the geochemical evolution of the Earth. However, mechanism and time scale of melt transport from the source to the surface are still not well understood and are dependent on the grain-scale distribution of melt. A related question is the retention of melt in partially molten regions of the Earth's upper mantle. Seismic observations from mid-ocean ridges (MOR) and subduction zones are interpreted to show in-situ melt contents up to 3%, while geochemical observations from MOR basalts are inferred to indicate very efficient extraction of melt (porosities of order of 0.1%). Earlier theoretical models of the melt distribution were based on the balance of surface tension between melt and uniform crystalline grains, predicting a simple network of melt along three-grain edges. Analyses of experimentally produced samples of olivine and basaltic melt show that the melt geometry is much more complex, and includes wetted two-grain boundaries. I reconstructed the 3-D model of melt geometry of two experimentally produced samples by serial sectioning and rendering of the pore space which demonstrates for the first time that melt exists in thin layers on two-grain boundaries. This confirms the inferences from previous 2-D observations and has significant implications for physical properties of partially molten regions, for example seismic velocities and attenuation. The wetted two-grain boundaries are inferred to be a consequence of continuous grain growth. Due to the complexity of the 3-D melt geometry the permeability of partially molten rocks can not be predicted from simple models. I therefore investigated the permeability as a function of porosity for both synthetic and experimentally determined pore geometries using a lattice-Boltzmann method. The calculated permeability is not a simple function of porosity, but increases rapidly at a critical fraction of wetted two-grain boundaries. To extrapolate the experimentally based

  8. Logistics Reduction: Heat Melt Compactor

    Data.gov (United States)

    National Aeronautics and Space Administration — The Advanced Exploration Systems (AES) Logistics Reduction (LR) project Heat Melt Compactor (HMC) technology is a waste management technology. Currently, there are...

  9. Role of crucible partition in improving Czochralski melt conditions

    Science.gov (United States)

    Jafri, I. H.; Prasad, V.; Anselmo, A. P.; Gupta, K. P.

    1995-09-01

    Many of the inhomogeneities and defects in the crystal grown from a pool of melt are because of the inherent unsteady growth kinetics and flow instabilities of the process. A scaled up version of the Czochralski process induces oscillatory and turbulent conditions in the melt, thereby resulting in the production of non-uniform silicon crystals. This numerical study reveals that a crucible partition shorter than the melt height can significantly improve the melt conditions. The obstruction at the bottom of the crucible is helpful but the variations in heat flux and flow patterns remain random. However, when the obstruction is introduced at the top of the melt, the flow conditions become much more desirable and oscillations are greatly suppressed. It is also found that a full-melt height partition or a double-crucible may not be a good choice. An optimal size of the blockage and its location to produce the most desirable process conditions will depend on the growth parameters including the melt height and the crucible diameter. These findings should be particularly useful in designing a solid polysilicon pellets-feed continuous Czochralski process for Si crystals.

  10. Hysteresis loops and the demagnetization process at 4.2 K for melt-spun Nd sub 1 sub 3 Fe sub 7 sub 7 B sub 1 sub 0

    CERN Document Server

    Jin Han Min; Park, W S; Park, M J; Wang Xue Feng

    1998-01-01

    Hysteresis loops of melt-spun Nd sub 1 sub 3 Fe sub 7 sub 7 B sub 1 sub 0 cooled down at the remanent state were measured at 4.2 K. The loop for fields of H sub m sub a sub x =6.4 MA m sup - sup 1 is characterized by low- and high-field steps. The loop for fields of H sub m sub a sub x =4.0 MA m sup - sup 1 is very thin with only a low-field step and is shifted profoundly along the H-axes. The loops and the spin distribution during the demagnetization process were analysed by micromagnetic finite-element calculations. Quantitatively, the calculations reproduce the experimental loops fairly well. The spin distribution is fairly nonuniform, and a domain-wall-like distribution appears not only at some grain boundaries but also within some grains at the high-field step. The demagnetization proceeds by nonuniform reversion as a whole, and neither the model of single-domain reversion nor the model of domain-wall pinning in the grain boundary model describes the process appropriately. (author)

  11. Continuous eclogite melting and variable refertilisation in upwelling heterogeneous mantle.

    Science.gov (United States)

    Rosenthal, Anja; Yaxley, Gregory M; Green, David H; Hermann, Joerg; Kovács, István; Spandler, Carl

    2014-08-18

    Large-scale tectonic processes introduce a range of crustal lithologies into the Earth's mantle. These lithologies have been implicated as sources of compositional heterogeneity in mantle-derived magmas. The model being explored here assumes the presence of widely dispersed fragments of residual eclogite (derived from recycled oceanic crust), stretched and stirred by convection in the mantle. Here we show with an experimental study that these residual eclogites continuously melt during upwelling of such heterogeneous mantle and we characterize the melting reactions and compositional changes in the residue minerals. The chemical exchange between these partial melts and more refractory peridotite leads to a variably metasomatised mantle. Re-melting of these metasomatised peridotite lithologies at given pressures and temperatures results in diverse melt compositions, which may contribute to the observed heterogeneity of oceanic basalt suites. We also show that heterogeneous upwelling mantle is subject to diverse local freezing, hybridization and carbonate-carbon-silicate redox reactions along a mantle adiabat.

  12. Nanorheology of Entangled Polymer Melts

    Science.gov (United States)

    Ge, Ting; Grest, Gary S.; Rubinstein, Michael

    2018-02-01

    We use molecular simulations to probe the local viscoelasticity of an entangled polymer melt by tracking the motion of embedded nonsticky nanoparticles (NPs). As in conventional microrheology, the generalized Stokes-Einstein relation is employed to extract an effective stress relaxation function GGSE(t ) from the mean square displacement of NPs. GGSE(t ) for different NP diameters d are compared with the stress relaxation function G (t ) of a pure polymer melt. The deviation of GGSE(t ) from G (t ) reflects the incomplete coupling between NPs and the dynamic modes of the melt. For linear polymers, a plateau in GGSE(t ) emerges as d exceeds the entanglement mesh size a and approaches the entanglement plateau in G (t ) for a pure melt with increasing d . For ring polymers, as d increases towards the spanning size R of ring polymers, GGSE(t ) approaches G (t ) of the ring melt with no entanglement plateau.

  13. Melt impregnation as a post processing treatment for performance enhancement in high capacity 3D microporous tin-copper-nickel intermetallic anode for Li-ion battery supported by electrodeposited nickel scaffold: A structural study

    Science.gov (United States)

    Sengupta, Srijan; Patra, Arghya; Mitra, Arijit; Jena, Sambedan; Das, Karabi; Majumder, Subhasish Basu; Das, Siddhartha

    2018-05-01

    This paper communicates stabilization of a Sn anode by impregnating it within the porous framework of a Ni-scaffold. The impregnation is carried out by electrodeposition Sn on Ni-foam followed by heating at 300 °C for 1 h. The Ni-foam was also electrodeposited on a Cu foil prior to deposition of Sn. The melting step leads to the formation of Nisbnd Sn and Cusbnd Sn intermetallics within pores of the Ni-scaffold. Snsbnd Cu/Ni intermetallics lithiate following the active-inactive strategy in which the inactive Cu/Ni buffers the volume expansion while Sn lithiates. Furthermore, this entire process takes place within Ni-scaffold which resists material pulverization and delamination and provide better electronic pathway for charge transfer. This active-inactive Sn:Snsbnd Cu/Ni intermetallic within a protected Ni-scaffold assembly results in 100th cycle discharge capacity of 587.9 mA h/g at a rate of 500 mA/g (0.5 C), and superior rate capability delivering 463 mAh/g at a rate of 2 A/g (2 C) while retaining structural integrity as compared to pure Sn electrodeposited (without heat-treatment) on the nickel scaffold.

  14. Linking Polymer Dynamics to Melt Processing

    Indian Academy of Sciences (India)

    Ashish Lele

    Dynamics at the Wall. ReptaUon of bulk chains. CR. AR. RetracUon due to shear. CCR. Brochard & de Gennes, 1992. λCR˙ γ ≈1. V s. * ~ N−1P−3. Joshi, Lele, Mashelkar 2001. Orientation time ~ 1/˙ γ I. Constraint release time ~ 1/˙ γ B. N. P ...

  15. Process optimisation in selective laser melting

    NARCIS (Netherlands)

    van Vaerenbergh, J.

    2008-01-01

    The work presented here summarises part of the work I have done for the past six years. After a few interesting months of research on laser cutting of thick steel plates, I was lucky to land up in the emerging domain of Rapid Prototyping (RP): producing complex products layer by layer, directly from

  16. About Eddy Currents in Induction Melting Processes

    Directory of Open Access Journals (Sweden)

    Gafiţa Nicolae-Bogdan

    2008-05-01

    Full Text Available In this paper we present a method forcomputing the eddy currents in induction meltingprocesses for non-ferrous alloys. We take intoconsideration the situation when only the crucible ismoving, inside the coils. This fact makes differentialcomputation methods to be hard to apply, because isnecessary to generate a new mesh and a new systemmatrix for every for every new position of the cruciblerelated to the coils. Integral methods cancel thisdrawback because the mesh is generated only for thedomains with eddy currents. For integral methods, themesh and the inductance matrix remain unchangedduring the movement of the crucible; only the free termsof the equation system will change.

  17. Diffusive fractionation of U-series radionuclides during mantle melting and shallow-level melt cumulate interaction

    Science.gov (United States)

    Van Orman, James A.; Saal, Alberto E.; Bourdon, Bernard; Hauri, Erik H.

    2006-09-01

    U-series radioactive disequilibria in basaltic lavas have been used to infer many important aspects of melt generation and extraction processes in Earth's mantle and crust, including the porosity of the melting zone, the solid mantle upwelling rate, and the melt transport rate. Most of these inferences have been based on simplified theoretical treatments of the fractionation process, which assume equilibrium partitioning of U-series nuclides among minerals and melt. We have developed a numerical model in which solid-state diffusion controls the exchange of U-series nuclides among multiple minerals and melt. First the initial steady-state distribution of nuclides among the phases, which represents a balance between diffusive fluxes and radioactive production and decay, is calculated. Next, partial melting begins, or a foreign melt is introduced into the system, and nuclides are again redistributed among the phases via diffusion. U-series nuclides can be separated during this stage due to differences in their diffusivity; radium in particular, and possibly protactinium as well, can be strongly fractionated from slower-diffusing thorium and uranium. We show that two distinct processes are not required for the generation of 226Ra and 230Th excesses in mid-ocean ridge basalts, as has been argued previously; instead the observed negative correlations of the ( 226Ra/ 230Th) activity ratio with ( 230Th/ 238U) and with the extent of trace element enrichment may result from diffusive fractionation of Ra from Th during partial melting of the mantle. Alternatively, the ( 226Ra/ 230Th) disequilibrium in mid-ocean ridge basalts may result from diffusive fractionation during shallow-level interaction of mantle melts with gabbroic cumulates, and we show that the results of the interaction have a weak dependence on the age of the cumulate if both plagioclase and clinopyroxene are present.

  18. Mathematical modeling of melting during laser heating of metal plate

    Directory of Open Access Journals (Sweden)

    Purin Mikhail

    2017-01-01

    Full Text Available The mathematical modeling of heat transfer processes proceeding together under the conditions of intense phase transformations (melting and metal evaporation under laser action on a metal plate has been carried out. The analysis of the results has showed that increasing of the laser radiation (ql power leads to acceleration of the melting process. However, it has been found that the change in the melting dynamics with variation of ql is characteristic only for the plates made of iron and copper. At the same time, it has been found that an increase in ql does not affect significantly the melting rate of the aluminum plates. It has been established that when the laser is exposed to a plate, zones with large temperature gradients are formed which can cause thermal stresses.

  19. [Pelletization of melts and liquids].

    Science.gov (United States)

    Rabisková, Miloslava

    2011-04-01

    During the second half of the last century, pelletization methods based on wetting were developed, e.g. agglomeration in coating pans, pelletization plates or fluid-bed equipment, layering of the drug in solution or suspension on inactive spherical cores, extrusion/spheronization and later on also rotoagglomeration in rotogranulators or rotoprocessors. These technologies have become a requisite part of industrial production of solid dosage forms. At present, numerous experimental papers deal with pellet preparation from melts and liquids. These new pelletization methods are the topic of the present article. Pellet preparation from melts is represented by three methods, i.e. fluid hot melt agglomeration, hot melt extrusion, and freeze pelletization. Jet cutting and cryopelletization are the techniques dealing with pellet preparation from liquids.

  20. Electric melting furnace for waste solidification

    International Nuclear Information System (INIS)

    Masaki, Toshio.

    1990-01-01

    To avoid electric troubles or reduction of waste processing performance even when platinum group elements are contained in wastes to be applied with glass solidification. For this purpose, a side electrode is disposed to the side wall of a melting vessel and a central electrode serving as a counter electrode is disposed about at the center inside the melting vessel. With such a constitution, if conductive materials are deposited at the bottom of the furnace or the bottom of the melting vessel, heating currents flow selectively between the side electrode and the central electrode. Accordingly, no electric currents flow through the conductive deposits thereby enabling to prevent abnormal heating in the bottom of the furnace. Further, heat generated by electric supply between the side electrode and the central electrode is supplied efficiently to raw material on the surface of the molten glass liquid to improve the processing performance. Further, disposition of the bottom electrode at the bottom of the furnace enables current supply between the central electrode and the bottom electrode to facilitate the temperature control for the molten glass in the furnace than in the conventional structure. (I.S.)

  1. Detection of structural heterogeneity of glass melts

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    2004-01-01

    The structural heterogeneity of both supercooled liquid and molten states of silicate has been studied using calorimetric method. The objects of this study are basaltic glasses and liquids. Two experimental approaches are taken to detect the structural heterogeneity of the liquids. One...... is discussed. The ordered structure of glass melts above the liquidus temperature is indirectly characterized by use of X-ray diffraction method. The new approaches are of importance for monitoring the glass melting and forming process and for improving the physical properties of glasses and glass fibers....... is the hyperquench-anneal-calorimetric scan approach, by which the structural information of a basaltic supercooled liquid and three binary silicate liquids is acquired. Another is the calorimetrically repeated up- and downscanning approach, by which the structural heterogeneity, the intermediate range order...

  2. Materials developed by mechanical alloying and melt spinning

    OpenAIRE

    Suñol Martínez, Joan Josep; Fort, Joaquim

    2008-01-01

    Materials science is a multidisciplinary research topic related to the development of physics and technology. Mechanical alloying of ribbon flakes is a two steps route to develop advanced materials. In this work, a Fe based alloy was obtained using three pathways: mechanical alloying, melt-spinning and mechanical alloying of previously melt-spun samples. Processing conditions allow us to obtain amorphous or nanocrystalline structures. Furthermore, a bibliographic revision of mechanical al...

  3. Devolatilization or melting of carbonates at Meteor Crater, AZ?

    Science.gov (United States)

    Hörz, F.; Archer, P. D.; Niles, P. B.; Zolensky, M. E.; Evans, M.

    2015-06-01

    We have investigated the carbonates in the impact melts and in a monolithic clast of highly shocked Coconino sandstone of Meteor Crater, AZ to evaluate whether melting or devolatilization is the dominant response of carbonates during high-speed meteorite impact. Both melt- and clast-carbonates are calcites that have identical crystal habits and that contain anomalously high SiO2 and Al2O3. Also, both calcite occurrences lack any meteoritic contamination, such as Fe or Ni, which is otherwise abundantly observed in all other impact melts and their crystallization products at Meteor Crater. The carbon and oxygen isotope systematics for both calcite deposits suggest a low temperature environment (impact melts, yield 100 wt% element totals by EMPA, suggesting complete loss of CO2. The target dolomite decomposed into MgO, CaO, and CO2; the CO2 escaped and the CaO and MgO combined with SiO2 from coexisting quartz and FeO from the impactor to produce the dominant impact melt at Meteor Crater. Although confined to Meteor Crater, these findings are in stark contrast to Osinski et al. (2008) who proposed that melting of carbonates, rather than devolatilization, is the dominant process during hypervelocity impact into carbonate-bearing targets, including Meteor Crater.

  4. Theoretical study of melting curves on Ta, Mo, and W at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Xi Feng [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang (China)], E-mail: hawk_0816@yahoo.com.cn; Cai Lingcang [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, P.O. Box 919-102, 621900 Mianyang (China)

    2008-06-01

    The melting curves of tantalum (Ta), molybdenum (Mo), and tungsten (W) are calculated using a dislocation-mediated melting model. The calculated melting curves are in good agreement with shock-wave data, and partially in agreement with wire explosion and piston-cylinder data, but show large discrepancies with diamond-anvil cell (DAC) data. We propose that the melting mechanism caused by shock-wave and laser-heated DAC techniques are probably different, and that a systematic difference exists in the two melting processes.

  5. The effect of melting temperature and time on the TiC particles

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Kun [Key Laboratory of Materials Liquid Structure and Heredity, Ministry of Education, Shandong University, Ji' nan 250061 (China); Liu Xiangfa, E-mail: xfliu@sdu.edu.c [Key Laboratory of Materials Liquid Structure and Heredity, Ministry of Education, Shandong University, Ji' nan 250061 (China)

    2009-09-18

    In the present work, the microstructure formation process and particle size distribution of TiC in Al-Ti-C master alloys are investigated by particle size analysis, which is based on the morphology characterizing from scanning electron microscopy (SEM). The TiC particle size distributions at different melting temperatures and during different melting times are researched. It is demonstrated that the TiC particle sizes increase with melting temperature and melting time elapsed. The micro size particles appear when the melting temperature is high enough.

  6. Scrap melting model for steel converter founded on interfacial solid/liquid phenomena

    Science.gov (United States)

    Kruskopf, Ari; Holappa, Lauri

    2017-12-01

    The primary goal in steel converter operation is the removal of carbon from the hot metal. This is achieved by blowing oxygen into the melt. The oxidation of carbon produces a lot of heat. To avoid too high temperatures in the melt cold scrap (recycled steel) is charged into the converter. The melting rate is affected by heat and carbon mass transfer. A process model for steel converter is in development. This model is divided into several modules, which are fluid dynamics, heat- and mass-transfer, scrap melting and chemical reactions. This article focuses on the development of the scrap melting module. A numerical model for calculating temperature and carbon concentration in the melt is presented. The melt model is connected with the solid scrap model via solid/liquid interface. The interface model can take into account solidification of iron melt, melting of solidified layer, a situation without such phase changes, and scrap melting. The aim is to predict the melting rate of the scrap including the properties of the hot metal. The model is tested by calculating the melting rates for different scrap thicknesses. All of the stages in the interface model were taking place in the test calculations.

  7. Experiments and analyses on melt-structure-water interactions during severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Seghal, B.R.; Dinh, T.N.; Bui, V.A.; Green, J.A.; Nourgaliev, R.R.; Okkonen, T.O.; Dinh, A.T. [Royal Inst. of Tech., Stockholm (Sweden). Div. of Nuclear Power Safety

    1998-04-01

    This report is the final report for the research project Melt Structure Water Interactions (MSWI). It describes results of analytical and experimental studies concerning MSWI during the course of a hypothetical core meltdown accident in a LWR. Emphasis has been placed on phenomena which govern vessel failure mode and timing and the mechanisms and properties which govern the fragmentation and breakup of melt jets and droplets. It was found that: 2-D effects significantly diminished the focusing effect of an overlying metallic layer on top of an oxide melt pool. This result improves the feasibility of in-vessel retention of a melt pool through external cooling of the lower head; phenomena related to hole ablation and melt discharge, in the event of vessel failure, are affected significantly by crust formation; the jet fragmentation process is a function of many related phenomena. The fragmentation rate depends not only on the traditional parameters but also on the melt physical properties, which change as the melt cools down from liquid to solid temperature; film boiling was investigated by developing a two-phase flow model and inserting it in a multi-D fluid dynamics code. It was concluded that the thickness of the film on the surface of a melt jet would be small and that the effects of the film on the process should not be large. This conclusion is contrary to the modeling employed in some other codes. The computer codes were developed and validated against the data obtained in the MSWI Project. The melt vessel interaction thermal analysis code describes the process of melt pool formation and convection and the resulting vessel thermal loadings. In addition, several innovative models were developed to describe the melt-water interaction process. The code MELT-3D treats the melt jet as a collection of particles whose movement is described with a three-dimensional Eulerian formulation. The model (SIPHRA) tracks the melt jet with an additional equation, using the

  8. Observation of melting conditions in selective laser melting of metals (SLM)

    Science.gov (United States)

    Thombansen, U.; Abels, Peter

    2016-03-01

    Process observation in 3D printing of metals currently is one of the central challenges. Many companies strive to employ this additive manufacturing process in their production chains in order to gain competitive advantages through added flexibility in product design and embedded features. The new degrees of freedom are accompanied with the challenge to manufacture every detail of the product to the predefined specifications. Products with filigree internal structures for example require a perfect build to deliver the performance that was designed into these structures. Melting conditions determine properties such as grain structure and density of the finished part before it is sent to post processing steps. Monitoring of such melting conditions is still a challenge where the use of photodiodes, pyrometry and camera systems contribute to an overall picture that might identify errors or deviations during the build process. Additional considerations must be made to decide if these sensors are applied coaxially or from a lateral perspective. Furthermore, setting parameters of focal plane array (FPA) sensors are discussed and events that are seen in the machine vision image are compared against the pyrometry data. The resume of the experiments suggests the application of multiple sensors to the selective laser melting process (SLM) as they jointly contribute to an identification of events. These events need to be understood in order to establish cause effect relationships in the future.

  9. Tenoumer impact crater, Mauritania: Impact melt genesis from a lithologically diverse target

    Science.gov (United States)

    Schultze, Dina Simona; Jourdan, Fred; Hecht, Lutz; Reimold, Wolf Uwe; Schmitt, Ralf-Thomas

    2016-02-01

    Impact melt rocks from the 1.9 km diameter, simple bowl-shaped Tenoumer impact crater in Mauritania have been analyzed chemically and petrologically. They are heterogeneous and can be subdivided into three types based on melt matrix color, occurrence of lithic clast components, amount of vesiculation (melt degassing), different proportions of carbonate melt mingled into silicate melt, and bulk rock chemical composition. These heterogeneities have two main causes (1) due to the small size of the impact crater, there was probably no coherent melt pool where a homogeneous mixture of melts, derived from different target lithologies, could be created; and (2) melt rock heterogeneity occurring at the thin section scale is due to fast cooling during and after the dynamic ejection and emplacement process. The overall period of crystal growth from these diverse melts was extremely short, which provides a further indication that complete chemical equilibration of the phases could not be achieved in such short time. Melt mixing processes involved in the generation of impact melts are, thus, recorded in nonequilibrium growth features. Variable mixing processes between chemically different melt phases and the formation of hybrid melts can be observed even at millimeter scales. Due to extreme cooling rates, different mixing and mingling stages are preserved in the varied parageneses of matrix minerals and in the mineral chemistry of microlites. 40Ar39Ar step-heating chronology on specimens from three melt rock samples yielded five concordant inverse isochron ages. The inverse isochron plots show that minute amounts of inherited 40Ar* are present in the system. We calculated a weighted mean age of 1.57 ± 0.14 Ma for these new results. This preferred age represents a refinement from the previous range of 21 ka to 2.5 Ma ages based on K/Ar and fission track dating.

  10. Melting behaviour of raw materials and recycled stone wool waste

    DEFF Research Database (Denmark)

    Schultz-Falk, Vickie; Agersted, Karsten; Jensen, Peter Arendt

    2018-01-01

    Stone wool is a widely used material for building insulation, to provide thermal comfort along with fire stability and acoustic comfort for all types of buildings. Stone wool waste generated either during production or during renovation or demolition of buildings can be recycled back into the stone...... indicates that the wool waste initiates melting at a lower temperature than the conventional charge. Also DSC measurements show that the wool waste requires less energy for heating and melting than the conventional charge, making stone wool waste recycling desirable both for environmental and for process...... wool melt production. This study investigates and compares the thermal response and melting behaviour of a conventional stone wool charge and stone wool waste. The study combines differential scanning calorimetry (DSC), hot stage microscopy (HSM) and X-ray diffraction (XRD). DSC reveals...

  11. Method of melting to solidify radioactive powder wastes

    International Nuclear Information System (INIS)

    Ootsuka, Katsuyuki; Miyazaki, Hitoshi.

    1981-01-01

    Purpose: To improve the microwave irradiation efficiency in a melting furnace. Constitution: Pelletization, sludgification and granularization are carried out as powderous dust reducing treatment. In the granularization, for example, radioactive burning ashes are sent from a hopper to a mixer and mixed with processing aids such as binders. Then, they are pelletized in a pelletizer into granular products and sent to a microwave melting furnace by way of a sieve screen. The granular products are melted by microwaves from a microwave guide tube and taken out through an exit. This can prevent powderous dusts from floating and scattering in the melting furnace and prevent the reduction in the microwave irradiation efficiency due to generation of electric discharges. (Seki, T.)

  12. Slab melting and magma formation beneath the southern Cascade arc

    Science.gov (United States)

    Walowski, Kristina J.; Wallace, Paul J.; Clynne, Michael A.; Rasmussen, D.J.; Weis, D.

    2016-01-01

    The processes that drive magma formation beneath the Cascade arc and other warm-slab subduction zones have been debated because young oceanic crust is predicted to largely dehydrate beneath the forearc during subduction. In addition, geochemical variability along strike in the Cascades has led to contrasting interpretations about the role of volatiles in magma generation. Here, we focus on the Lassen segment of the Cascade arc, where previous work has demonstrated across-arc geochemical variations related to subduction enrichment, and H-isotope data suggest that H2O in basaltic magmas is derived from the final breakdown of chlorite in the mantle portion of the slab. We use naturally glassy, olivine-hosted melt inclusions (MI) from the tephra deposits of eight primitive (MgO>7 wt%) basaltic cinder cones to quantify the pre-eruptive volatile contents of mantle-derived melts in this region. The melt inclusions have B concentrations and isotope ratios that are similar to mid-ocean ridge basalt (MORB), suggesting extensive dehydration of the downgoing plate prior to reaching sub-arc depths and little input of slab-derived B into the mantle wedge. However, correlations of volatile and trace element ratios (H2O/Ce, Cl/Nb, Sr/Nd) in the melt inclusions demonstrate that geochemical variability is the result of variable addition of a hydrous subduction component to the mantle wedge. Furthermore, correlations between subduction component tracers and radiogenic isotope ratios show that the subduction component has less radiogenic Sr and Pb than the Lassen sub-arc mantle, which can be explained by melting of subducted Gorda MORB beneath the arc. Agreement between pMELTS melting models and melt inclusion volatile, major, and trace element data suggests that hydrous slab melt addition to the mantle wedge can produce the range in primitive compositions erupted in the Lassen region. Our results provide further evidence that chlorite-derived fluids from the mantle portion of the

  13. How Greenland melts

    Directory of Open Access Journals (Sweden)

    van den Broeke M.R.

    2010-12-01

    Full Text Available Satellite altimetry and gravimetry show that the Greenland ice sheet has been losing volume and mass since the beginning of this century. However, from these short time series of direct measurements we cannot infer what the causes of the mass loss are, i.e. ice dynamics or surface processes, or that maybe the ice sheet returns to normal after a period of volume increase and mass gain. By modelling and observing the individual components of the ice sheet mass balance, i.e. snowfall, meltwater runoff and iceberg production, we are able to identify the processes that led to the recent mass loss. We conclude that the Greenland ice sheet is significantly out of balance. Acceleration of outlet glaciers and increased runoff have contributed equally to recent Greenland mass loss. The potential for mass loss by surface processes, however, was three times greater than actually observed, due to refreezing and enhanced snowfall.

  14. Lithium diffusion in silicate melts

    Science.gov (United States)

    Cunningham, G. J.; Henderson, P.; Lowry, R. K.; Nolan, J.; Reed, S. J. B.; Long, J. V. P.

    1983-10-01

    The diffusion properties of Li in an andesitic and pitchstone melt have been determined over the temperature range 1300-1400°C. The diffusion data have been fitted to an Arrhenius relationship between log D0 and 1/ T, and give relatively small activation energies of diffusion: 21.4±5.8 kcal mol -1 in the andesite and 20.1±2.8 kcal mol -1 in the pitchstone. Li +, unlike several other cations, shows similar diffusivities in these melt compositions to that in a basaltic melt. Despite the similar ionic radius of Li + to that of Co 2+, the diffusion properties of the two ions are very different from each other.

  15. Manufacturing of implants by selective laser melting

    Directory of Open Access Journals (Sweden)

    Cosma Sorin Cosmin

    2012-09-01

    Full Text Available In recent years, digitizing and automation have gained an important place in fabrication of medical parts. Rapid Prototyping could be very suitable for medical applications due to their complex geometry, low volume and strong individualization. The presented study investigates the possibility to produce medical or dental parts by Selective Laser Melting (SLM. The SLM process is optimized and fully characterized for different biocompatible metal alloys, such as: TiAl6V4 and CoCrMo. The potential of SLM as medical manufacturing technique is proved by a developed procedure to fabricate frameworks for complex dental prostheses.

  16. Population balance modelling of fluidized bed melt granulation: an overview

    NARCIS (Netherlands)

    Tan, H.S.; Goldschmidt, M.J.V.; Boerefijn, R.; Hounslow, M.J.; Salman, A.; Kuipers, J.A.M.

    2005-01-01

    This paper presents an overview of the work undertaken by our group to identify and quantify the rates processes active in fluidized bed melt granulation (FBMG). The process involves the identification and development of physically representative models to mechanistically describe FBMG using both

  17. Binding Mechanisms in Selective Laser Sintering and Selective Laser Melting

    NARCIS (Netherlands)

    Kruth, J.P.; Mercelis, P.; Van Vaerenbergh, J.; van Vaerenbergh, J.; Froyen, L.; Rombouts, M.

    2005-01-01

    Purpose – This paper provides an overview of the different binding mechanisms in selective laser sintering (SLS) and selective laser melting (SLM), thus improving the understanding of these processes. Design/methodology/approach – A classification of SLS/SLM processes was developed, based on the

  18. Application of Microwave Melting for the Recovery of Tin Powder

    Directory of Open Access Journals (Sweden)

    Lei Xu

    2017-06-01

    Full Text Available The present work explores the application of microwave heating for the melting of powdered tin. The morphology and particle size of powdered tin prepared by the centrifugal atomization method were characterized. The tin particles were uniform and spherical in shape, with 90% of the particles in the size range of 38–75 μm. The microwave absorption characteristic of the tin powder was assessed by an estimation of the dielectric properties. Microwave penetration was found to have good volumetric heating on powdered tin. Conduction losses were the main loss mechanisms for powdered tin by microwave heating at temperatures above 150 °C. A 20 kW commercial-scale microwave tin-melting unit was designed, developed, and utilized for production. This unit achieved a heating rate that was at least 10 times higher than those of conventional methods, as well as a far shorter melting duration. The results suggest that microwave heating accelerates the heating rate and shortens the melting time. Tin recovery rate was 97.79%, with a slag ratio of only 1.65% and other losses accounting for less than 0.56%. The unit energy consumption was only 0.17 (kW·h·kg–1—far lower than the energy required by conventional melting methods. Thus, the microwave melting process improved heating efficiency and reduced energy consumption.

  19. Oscillatory convection in low aspect ratio Czochralski melts

    Science.gov (United States)

    Anselmo, A.; Prasad, V.; Koziol, J.; Gupta, K. P.

    1993-11-01

    Modeling of the crucible in bulk crystal growth simulations as a right circular cylinder may be adequate for high aspect ratio melts but this may be unrealistic when the melt height is low. Low melt height is a unique feature of a solid feed continuous Czochralski growth process for silicon single crystals currently under investigation. At low melt heights, the crucible bottom curvature has a dampening effect on the buoyancy-induced oscillations, a source of inhomogeneities in the grown crystal. The numerical results demonstrate how the mode of convection changes from vertical wall-dominated recirculating flows to Benard convection as the aspect ratio is lowered. This phenomenon is strongly dependent on the boundary condition at the free surface of the melt, which has been generally considered to be either adiabatic or radiatively cooled. A comparison of the flow oscillations in crucibles with and without curved bottoms at aspect ratios in the range of 0.25 to 0.50, and at realistic Grashof numbers (10 7 < Gr < 10 8) illustrate that changing the shape of the crucible may be an effective means of suppressing oscillations and controlling the melt flow.

  20. A metastable liquid melted from a crystalline solid under decompression

    Science.gov (United States)

    Lin, Chuanlong; Smith, Jesse S.; Sinogeikin, Stanislav V.; Kono, Yoshio; Park, Changyong; Kenney-Benson, Curtis; Shen, Guoyin

    2017-01-01

    A metastable liquid may exist under supercooling, sustaining the liquid below the melting point such as supercooled water and silicon. It may also exist as a transient state in solid-solid transitions, as demonstrated in recent studies of colloidal particles and glass-forming metallic systems. One important question is whether a crystalline solid may directly melt into a sustainable metastable liquid. By thermal heating, a crystalline solid will always melt into a liquid above the melting point. Here we report that a high-pressure crystalline phase of bismuth can melt into a metastable liquid below the melting line through a decompression process. The decompression-induced metastable liquid can be maintained for hours in static conditions, and transform to crystalline phases when external perturbations, such as heating and cooling, are applied. It occurs in the pressure-temperature region similar to where the supercooled liquid Bi is observed. Akin to supercooled liquid, the pressure-induced metastable liquid may be more ubiquitous than we thought.

  1. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  2. Synthesis of ammonia using sodium melt.

    Science.gov (United States)

    Kawamura, Fumio; Taniguchi, Takashi

    2017-09-14

    Research into inexpensive ammonia synthesis has increased recently because ammonia can be used as a hydrogen carrier or as a next generation fuel which does not emit CO 2 . Furthermore, improving the efficiency of ammonia synthesis is necessary, because current synthesis methods emit significant amounts of CO 2 . To achieve these goals, catalysts that can effectively reduce the synthesis temperature and pressure, relative to those required in the Haber-Bosch process, are required. Although several catalysts and novel ammonia synthesis methods have been developed previously, expensive materials or low conversion efficiency have prevented the displacement of the Haber-Bosch process. Herein, we present novel ammonia synthesis route using a Na-melt as a catalyst. Using this route, ammonia can be synthesized using a simple process in which H 2 -N 2 mixed gas passes through the Na-melt at 500-590 °C under atmospheric pressure. Nitrogen molecules dissociated by reaction with sodium then react with hydrogen, resulting in the formation of ammonia. Because of the high catalytic efficiency and low-cost of this molten-Na catalyst, it provides new opportunities for the inexpensive synthesis of ammonia and the utilization of ammonia as an energy carrier and next generation fuel.

  3. Thermodynamics of freezing and melting

    DEFF Research Database (Denmark)

    Pedersen, Ulf Rørbæk; Costigliola, Lorenzo; Bailey, Nicholas

    2016-01-01

    phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio...

  4. Chemistry modification of high oxygen-carbon powder by plasma melting

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, P.S.; Korzekwa, D.R.; Garcia, F.G.

    1996-01-01

    State-of-the-art melting of tantalum and tantalum alloys has relied on electron beam (EB) or vacuum-arc remelting (VAR) for commercial ingot production. The limited number of melting techniques for these materials are the result of high melting temperatures and reactivity with conventional mold/crucible materials. In addition, the required vacuum levels used in the EB and VAR processes limit these techniques to relatively low interstitial content material due toe extensive outgassing during melting. Plasma arc melting (PAM) provides and alternative for melting tantalum and offers the advantage or processing under inert or other gases rather than vacuum, The plasma process is not sensitive to materials outgassing and allows for the direct recycling of material that would otherwise be reprocessed by chemical extraction. The current work examines melting of high interstitial content tantalum powder by the plasma arc process. Various cover gases of argon-hydrogen and helium-hydrogen were investigated to determine best melt quality. Melted ingots were characterized by chemical and metallographic methods to determine overall interstitial content, compound and morphology.

  5. Crust behavior and erosion rate prediction of EPR sacrificial material impinged by core melt jet

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gen; Liu, Ming, E-mail: ming.liu@mail.xjtu.edu.cn; Wang, Jinshi; Chong, Daotong; Yan, Junjie

    2017-04-01

    Highlights: • A numerical code was developed to analyze melt jet-concrete interaction in the frame of MPS method. • Crust and ablated concrete layer at UO{sub 2}-ZrO{sub 2} melt and concrete interface periodically developed and collapsed. • Concrete surface temperature fluctuated around a low temperature and ablation temperature. • Concrete erosion by Fe-Zr melt jet was significantly faster than that by UO{sub 2}-ZrO{sub 2} melt jet. - Abstract: Sacrificial material is a special ferro-siliceous concrete, designed in the ex-vessel core melt stabilization system of European Pressurized water Reactor (EPR). Given a localized break of RPV lower head, the melt directly impinges onto the dry concrete in form of compact jet. The concrete erosion behavior influences the failure of melt plug, and further affects melt spreading. In this study, a numerical code was developed in the frame of Moving Particle Semi-implicit (MPS) method, to analyze the crust behavior and erosion rate of sacrificial concrete, impinged by prototypic melt jet. In validation of numerical modeling, the time-dependent erosion depth and erosion configuration matched well with the experimental data. Sensitivity study of sacrificial concrete erosion indicates that the crust and ablated concrete layer presented at UO{sub 2}-ZrO{sub 2} melt and concrete interface, whereas no crust could be found in the interaction of Fe-Zr melt with concrete. The crust went through stabilization-fracture-reformation periodic process, accompanied with accumulating and collapsing of molten concrete layer. The concrete surface temperature fluctuated around a low temperature and ablation temperature. It increased as the concrete surface layer was heated to melting, and dropped down when the cold concrete was revealed. The erosion progression was fast in the conditions of small jet diameter and large concrete inclination angle, and it was significantly faster in the erosion by metallic melt jet than by oxidic melt jet.

  6. Uranium and neodymium partitioning in alkali chloride melts using low-melting gallium-based alloys

    Directory of Open Access Journals (Sweden)

    Melchakov Stanislav Yu.

    2015-12-01

    Full Text Available Partitioning of uranium and neodymium was studied in a ‘molten chloride salt - liquid Ga-X (X = In or Sn alloy’ system. Chloride melts were based on the low-melting ternary LiCl-KCl-CsCl eutectic. Nd/U separation factors were calculated from the thermodynamic data as well as determined experimentally. Separation of uranium and neodymium was studied using reductive extraction with neodymium acting as a reducing agent. Efficient partitioning of lanthanides (Nd and actinides (U, simulating fission products and fissile materials in irradiated nuclear fuels, was achieved in a single stage process. The experimentally observed Nd/U separation factor valued up to 106, depending on the conditions.

  7. High Resolution Melting Analysis for fast and cheap polymorphism screening of marine populations

    OpenAIRE

    sprotocols

    2015-01-01

    Authors: Anne-Leila Meistertzheim, Isabelle Calves, Sébastien Artigaud, Carolyn S. Friedman, Christine Paillard, Jean Laroche & Claude Ferec ### Abstract This protocol permits the mutation scanning of PCR products by high-resolution DNA melting analysis requiring the inclusion of a saturating intercalating dye in the PCR mix without labelled probe. During a scanning process, fluorescent melting curves of PCR amplicons are analyzed. Mutations modifying melting curve shapes, are allowed...

  8. Heat and mass transfer in the melting of frost

    CERN Document Server

    Mohs, William F

    2015-01-01

    This Brief is aimed at engineers and researchers involved in the refrigeration industry: specifically, those interested in energy utilization and system efficiency. The book presents what the authors believe is the first comprehensive frost melting study involving all aspects of heat and mass transfer. The volume’s description of in-plane and normal digital images of frost growth and melting is also unique in the field, and the digital analysis technique offers an advantage over invasive measurement methods. The scope of book’s coverage includes modeling and experimentation for the frost formation and melting processes. The key sub-specialties to which the book are aimed include refrigeration system analysis and design, coupled heat and mass transfer, and phase-change processes.

  9. Oxidation effects during corium melt in-vessel retention

    Energy Technology Data Exchange (ETDEWEB)

    Almyashev, V.I.; Granovsky, V.S.; Khabensky, V.B.; Krushinov, E.V.; Sulatsky, A.A.; Vitol, S.A. [Alexandrov Scientific-Research Institute of Technology (NITI), Sosnovy Bor (Russian Federation); Gusarov, V.V. [Ioffe Institute, St. Petersburg (Russian Federation); Bechta, S. [Royal Institute of Technology (KHT), Stockholm (Sweden); Barrachin, M.; Fichot, F. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), St Paul lez Durance (France); Bottomley, P.D., E-mail: paul.bottomley@ec.europa.eu [Joint Research Centre, Institut für Transurane (ITU), Karlsruhe (Germany); Fischer, M. [AREVA GmbH, Erlangen (Germany); Piluso, P. [CEA Cadarache-DEN/DTN/STRI (France)

    2016-08-15

    Highlights: • Corium–steel interaction tests were re-examined particularly for transient processes. • Oxidation of corium melt was sensitive to oxidant supply and surface characteristics. • Consequences for vessel steel corrosion rates in severe accidents were discussed. - Abstract: In the in-vessel corium retention studies conducted on the Rasplav-3 test facility within the ISTC METCOR-P project and OECD MASCA program, experiments were made to investigate transient processes taking place during the oxidation of prototypic molten corium. Qualitative and quantitative data have been produced on the sensitivity of melt oxidation rate to the type of oxidant, melt composition, molten pool surface characteristics. The oxidation rate is a governing factor for additional heat generation and hydrogen release; also for the time of secondary inversion of oxidic and metallic layers of corium molten pool.

  10. Do cracks melt their way through solids?

    International Nuclear Information System (INIS)

    Okamoto, P. R.

    1998-01-01

    Real-time, in situ fracture studies in the high-voltage electron microscope (HVEM) show that microscopically thin regions of amorphous NiTi form ahead of moving crack tips in the B2-NiTi intermetallic compound during tensile straining at temperatures equal to or below 600K. The upper cutoff temperature of 600K for this stress-induced melting (or amorphization) is identical to the upper cutoff temperatures reported in the literature for both heavy-ion-induced amorphization of the intermetallic NiTi and ion-beam-mixing-induced amorphization of Ni and Ti multilayer. These results, together with the fact that the higher crystallization temperatures (∼800K)of unrelaxed amorphous NiTi alloys obtained by rapid quenching can also be reduced to, but not lower than 600K, by heavy-ion irradiation, strongly suggest that structural relaxation processes enhanced or induced by dynamic atomic disordering allow the formation of a unique, fully-relaxed glassy state which is characterized by a unique isothermal crystallization temperature. We believe that this unique temperature is the Kauzmann glass-transition temperature, corresponding to the ideal glass having the same entropy as the crystalline state. As the glassy state with the lowest global free energy, the preferential formation of this ideal glass by disorder-induced amorphization processes can be understood as the most energetically-favored, kinetically-constrained melting response of crystalline materials driven far from equilibrium at low temperatures

  11. Co-settling of Chromite and Sulfide Melt Droplets and Trace Element Partitioning between Sulfide and Silicate Melts

    Science.gov (United States)

    Manoochehri, S.; Schmidt, M. W.; Guenther, D.

    2013-12-01

    Gravitational settling of immiscible, dense sulfide melt droplets together with other cumulate phases such as chromite, combined with downward percolation of these droplets through a cumulate pile, is thought to be one of the possible processes leading to the formation of PGE rich sulfide deposits in layered mafic intrusions. Furthermore some chromitite seams in the Merensky Reef (Bushveld Complex) are considered to be acting as a filter or barrier for further downward percolation of sulfide melts into footwall layers. To investigate the feasibility of such mechanical processes and to study the partitioning behavior of 50 elements including transition metals and REEs (but not PGEs) between a silicate and a sulfide melt, two separate series of high temperature (1250-1380 °C) centrifuge-assisted experiments at 1000 g, 0.4-0.6 GPa were conducted. A synthetic silicate glass with a composition representative of the parental magma of the Bushveld Complex (~ 55 wt% SiO2) was mixed with pure FeS powder. For the first series of experiments, 15 or 25 wt% natural chromite with average grain sizes of ~ 5 or 31 μm were added to a mixture of silicate glass and FeS (10 wt%) adding 1 wt% water. For the second series, a mixture of the same glass and FeS was doped with 50 trace elements. These mixtures were first statically equilibrated and then centrifuged. In the first experimental series, sulfide melt droplets settled together with, but did not segregate from chromite grains even after centrifugation at 1000 g for 12 hours. A change in initial chromite grain size and proportions didn't have any effect on segregation. Without chromite, the starting mixture resulted in the formation of large sulfide melt pools together with finer droplets still disseminated through the silicate glass and both at the bottom of the capsule. The incomplete segregation of sulfide melt is interpreted as being due to high interfacial energies between sulfide and silicate melts/crystals which hinder

  12. Unsolved problems of crystallization and melting of flexible macromolecules

    International Nuclear Information System (INIS)

    Wunderlich, B.

    1992-01-01

    The thermodynamics, kinetics, and computer simulations of crystallization and melting is discussed. The thermodynamics is shown to be well understood, although for many specific crystals not enough details for full description are available. Experiments on the crystallization kinetics of poly(ethylene) and poly(oxyethylene) in the presence of crystal nuclei as a function of molecular mass revealed that with increasing mass, the crystallization behavior deviates increasingly from that of small, rigid molecules. Instead of showing a continuously changing, linear crystallization rate with temperature through the equilibrium melting temperature, T m 0 , these flexible macromolecules show a region of practically zero crystallization rate between T m 0 and about (T m 0 - 15) K, creating a temperature region of metastability in the melt that cannot be broken by nucleation with pregrown crystals. Molecular Nucleation was proposed as a cooperative process to be of overriding importance for the description of polymer crystallization, and to be at the center of segregation of molecules of lower molecular mass by growing crystal fronts. Initial efforts to model sufficiently large crystals using Monte Carlo and molecular dynamics methods are presented. Some of the short-time intermediates in the melting, crystallization, and annealing processes seem to have little similarity to commonly assumed models of crystallization and melting and are presented as discussion topics

  13. Study of hybrid laser / MAG welding process: characterization of the geometry and the hydrodynamics of the melt pool and development of a 3D thermal model; Etude du procede de soudage hybride laser/MAG: Caracterisation de la geometrie et de l'hydrodynamique du bain de fusion et developpement d'un modele 3D thermique

    Energy Technology Data Exchange (ETDEWEB)

    Le Guen, E.

    2010-11-15

    Hybrid laser/MIG-MAG welding shows high advantages compared to laser welding or GMAW arc welding used separately. Thanks to this process, higher productivity can be gained through higher welding speed, higher squeeze tolerance moreover possible improvement of the metallurgical properties of the weld seam can be obtained. However, many operating parameters have to be set up in order to achieve optimal process. The complex physical phenomena, which govern welding process, have to be understood in order to use efficiently this technique in mass production. Understanding of these phenomena is also necessary to program numerical simulations which fit to this process. In the first step, experimental studies have been carried out with GMAW, laser and hybrid welding on samples of S355 steel. Influence of operating parameters has been analyzed through films performed with speed camera and macro-graphies of weld seam cross section. Surface deformations of the melt pool, induced by the arc pressure, weld pool length, droplet detachment and welding speed, have been analyzed precisely from images of the surface melt pool. In a second step, a numerical model was developed using the COMSOL Multiphysics software for MAG, laser and hybrid laser/MAG welding processes. A 3D quasi-stationary model has been calculated from the temperature field within the metal. The originality of the MAG and hybrid model lies in the prediction of the melt pool surface profile used to determine the 3D geometry, by taking into account the material input. The influence of different parameters such as arc power and speed welding on the efficiency as well as the distribution radius of the arc power and the arc pressure are analyzed through validations with different experimental results and different calculation configurations. (author)

  14. Melt migration in Vesta and petrogenesis of eucrites and diogenites

    Science.gov (United States)

    Mizzon, Hugau; Monnereau, Marc; Toplis, Michael J.; Forni, Olivier; Prettyman, Thomas H.; McSween, Harry Y.

    2014-05-01

    Eucrites are pigeonite-plagioclase basalts and gabbros. Along with diogenites and howardites, they belong to the HED meteorite group, for which asteroid 4-Vesta is the likely parent. Basaltic eucrites form the upper crust of Vesta. They were produced either by direct equilibrium partial melting of an initial chondritic precursor, or complete melting followed by equilibrium crystallization. Diogenites are orthopyroxene and olivine cumulates that crystallized at depth, either as plutons or as a continuous layer below the eucrite crust. In addition, these rocks show evidence for a complex thermal history, with relatively rapid emplacement of basaltic crust, extensive crustal metamorphism, possible re-melting, and maybe even serial magmatism (McSween2010). Understanding the complexities of eucrite and diogenite petrogenesis requires identification of appropriate heat sources and modeling of the associated physical and chemical processes taking place during Vesta's differentiation. Concerning heat sources, geochemical analyses of various chondrite and achondrite meteorite groups indicate that the principal energy source driving differentiation in the early solar system was the short-lived radioisotope 26Al. This source of energy has important consequences for differentiation on asteroidal bodies, because Al is concentrated in the melt phase during early melting of plagioclase, and thus will be redistributed in the body due to melt migration. The separation velocity between a liquid and its residue is thus a critical parameter, this migration rate depending upon whether or not porosity is organized into a hierarchical network of veins (Wilson&Keil2012). Even if vein networks exist, their formation time is also of importance, but currently uncertain. In the case of rapid melt migration and extraction, eucrites can potentially form by direct equilibrium partial melting of the mantle. Depending on when the crust is emplaced, there is a possibility that sufficient 26Al will

  15. Constraints on the dynamics of melt migration, flow and emplacement across the continental crust

    Science.gov (United States)

    Cavalcante, Carolina; Viegas, Gustavo

    2015-04-01

    The presence of partial melting during deformation produces a drastic change in the rheological behavior of the continental crust. The rock strength decreases with melt fractions as low as ~0.7 %. At pressure/temperature conditions typical of the middle crust, melt-bearing systems may play a critical role in the processes of strain localization and in the overall strength of the continental lithosphere. In eastern Brazil, Neoproterozoic tectonics are often associated with wide partial melting and shear zone development, that promote the exhumation of mid- to lower crustal layers where compositionally heterogeneous anatexites with variable melt fractions and leucosome structures are exposed. The leucosomes usually form interconnected networks of magma that reflect the high melt content present during deformation. In this contribution we address two case studies encompassing the dynamics of melt flow at magma chambers, represented by the Carlos Chagas anatexite, and the mechanisms of melt migration and channeling through shear zones, in which the Patos shear zone serves as an analogue. Through detailed petrostructural studies of anatexites exposed at these settings, we aim to demonstrate the way melt deforms and localizes strain, the different patterns of melt flow pathways across the crust, and the implications for the mechanical behaviour of the Earth's lithosphere during orogenic deformation.

  16. Filament stretching rheometry of polymer melts

    DEFF Research Database (Denmark)

    Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

    2005-01-01

    The Filament Stretching Rheometry (FSR) method developed by Sridhar, McKinley and coworkers for polymer solutions has been extended to be used also for polymer melts. The design of a melt-FSR will be described and differences to conventional melt elongational rheometers will be pointed out. Results...

  17. Transient refractory material dissolution by a volumetrically-heated melt

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, Jean Marie, E-mail: jean-marie.seiler@cea.fr [CEA, DEN, DTN, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Ratel, Gilles [CEA, DEN, DTN, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Combeau, Hervé [Institut Jean Lamour, UMR 7198, Lorraine University, Ecole des Mines de Nancy, Parc de Saurupt, 54042 Nancy Cedex (France); Gaus-Liu, Xiaoyang; Kretzschmar, Frank; Miassoedov, Alexei [Karlsruhe Institut of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2014-12-15

    , the liquid composition at the interface is concentrated in the refractory species. During the transient, the interface temperature is equal to the liquidus temperature corresponding to the local and instantaneous composition of the liquid at the interface. Regarding the design of a protective layer made of refractory materials, we can answer the question of how much ceramic can be dissolved and its impact on melt temperature evolution during the dissolution process. It also impacts on subsequent corium solidification since the additional mass of dissolved ceramic leads to increased volume of the molten material, significantly increasing the time required for complete solidification. For the long term, ceramic material does not offer better confinement than a crust made of solidified corium. This work served as support to a generalisation of the model of transient evolution of interface temperature in various severe accident situations (Seiler and Combeau, 2014)

  18. Grain boundary melting in ice

    OpenAIRE

    Thomson, E. S.; Hansen-Goos, Hendrik; Wilen, L. A.; Wettlaufer, J. S.

    2012-01-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentr...

  19. Mobile Melt-Dilute Technology Development Project FY 2005 Test Report

    Energy Technology Data Exchange (ETDEWEB)

    David A. Sell; Donald Fisher

    2006-01-01

    The adaptation of Melt-Dilute technology to a mobile and deployable platform progressed with the installation of the prototype air-cooled induction furnace and power generator in an ISO cargo container. Process equipment tests were conducted in FY’05 on two fronts: the melt container and its associated hardware and the mobile furnace and generator. Container design was validated through tests at elevated temperature and pressure, under vacuum, and subjected to impact. The Mobile Melt-Dilute (MMD) furnace and power source tests were completed per the plan. The tests provided information necessary to successfully melt and dilute HEU research reactor fuel assemblies.

  20. Three dimensional numerical simulation for air flow field in melt blowing

    Science.gov (United States)

    Xie, Sheng; Han, Wanli; Jiang, Guojun

    2017-10-01

    Melt blowing is one-step approach for producing microfibrous nonwovens. In this study, the characteristics of air flow field in different die melt blowing were studied. CFD simulation analysis was adopted to complete the air flow field simulation. The characteristics of the air flow fields in different die melt blowing were revealed and compared. Meanwhile, the fiber paths in these two melt-blowing processes are recorded with a high-speed camera. The fiber path profiles, especially the whipping, are obtained and presented.

  1. Bubble Formation in Basalt-like Melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Keding, Ralf; Yue, Yuanzheng

    2011-01-01

    The effect of the melting temperature on bubble size and bubble formation in an iron bearing calcium aluminosilicate melt is studied by means of in-depth images acquired by optical microscopy. The bubble size distribution and the total bubble volume are determined by counting the number of bubbles...... and their diameter. The variation in melting temperature has little influence on the overall bubble volume. However, the size distribution of the bubbles varies with the melting temperature. When the melt is slowly cooled, the bubble volume increases, implying decreased solubility of the gaseous species. Mass...

  2. Rock species formation due to deep-mantle melting

    Science.gov (United States)

    Fomin, Ilya; Tackley, Paul

    2017-04-01

    Melting and melting migration are processes leading to chemically distinct rock species from a homogeneous substrate in the Earth mantle. Iron-rich melts and corresponding rock species are proposed to result from magma ocean progressive crystallization [Labrosse et al., 2007], and modern geophysical models of ULVZ (e.g. [Beuchert & Schmeling, 2013]) discuss their presence at around the CMB today. We perform long-term (tens of millions of years) numerical simulations of the Earth's mantle for a plausible range of CMB temperatures to understands the possibility of melting and it's consequences. Our model of melting is based on experimental data and ab initio simulations. Physical properties (liquid-solid density differences) are adjusted with data of [de Koker et al., 2013; Mosenfelder et al., 2007; Stixrude & Lithgow-Bertelloni, 2011; Thomas & Asimow, 2013]. This model is included in StagYY numerical code (e.g. [Tackley, 2008]) to simulate mass and thermal fluxes within the Earth mantle. Melt segregation (rocks' permeability and velocities) is considered using equations listed in [Abe, 1995; Solomatov, Stevenson, 1993; Martin & Nokes, 1989]. Thermal effects (adiabatic heating and viscous dissipation) are considered. Viscous dissipation term includes Darcy flux term, but omits highly non-linear Brinkman contribution [Nield, 2007]. Modeling predicts formation of melt if temperature at CMB exceeds 4000-4050K. It's segregation and reequilibration results in sufficient volumes of slightly iron-enriched melt lighter than solid counterpart and moving upward. However, it's propagation is strongly controlled by temperature. Partial melting atop the molten layer results in formation of refractory iron-poor restite which delaminates and sink down, so that a layer of iron-depleted material forms underneath the molten layer. Our model applied to homogeneous pyrolitic mantle results in formation of layers of iron-depleted material with average FeO around 4.6 mol.% and iron

  3. Seismic evidence of effects of water on melt transport in the Lau back-arc mantle.

    Science.gov (United States)

    Wei, S Shawn; Wiens, Douglas A; Zha, Yang; Plank, Terry; Webb, Spahr C; Blackman, Donna K; Dunn, Robert A; Conder, James A

    2015-02-19

    Processes of melt generation and transport beneath back-arc spreading centres are controlled by two endmember mechanisms: decompression melting similar to that at mid-ocean ridges and flux melting resembling that beneath arcs. The Lau Basin, with an abundance of spreading ridges at different distances from the subduction zone, provides an opportunity to distinguish the effects of these two different melting processes on magma production and crust formation. Here we present constraints on the three-dimensional distribution of partial melt inferred from seismic velocities obtained from Rayleigh wave tomography using land and ocean-bottom seismographs. Low seismic velocities beneath the Central Lau Spreading Centre and the northern Eastern Lau Spreading Centre extend deeper and westwards into the back-arc, suggesting that these spreading centres are fed by melting along upwelling zones from the west, and helping to explain geochemical differences with the Valu Fa Ridge to the south, which has no distinct deep low-seismic-velocity anomalies. A region of low S-wave velocity, interpreted as resulting from high melt content, is imaged in the mantle wedge beneath the Central Lau Spreading Centre and the northeastern Lau Basin, even where no active spreading centre currently exists. This low-seismic-velocity anomaly becomes weaker with distance southward along the Eastern Lau Spreading Centre and the Valu Fa Ridge, in contrast to the inferred increase in magmatic productivity. We propose that the anomaly variations result from changes in the efficiency of melt extraction, with the decrease in melt to the south correlating with increased fractional melting and higher water content in the magma. Water released from the slab may greatly reduce the melt viscosity or increase grain size, or both, thereby facilitating melt transport.

  4. Hf isotope evidence for effective impact melt homogenisation at the Sudbury impact crater, Ontario, Canada

    Science.gov (United States)

    Kenny, Gavin G.; Petrus, Joseph A.; Whitehouse, Martin J.; Daly, J. Stephen; Kamber, Balz S.

    2017-10-01

    We report on the first zircon hafnium-oxygen isotope and trace element study of a transect through one of the largest terrestrial impact melt sheets. The differentiated melt sheet at the 1.85 Ga, originally ca. 200 km in diameter Sudbury impact crater, Ontario, Canada, yields a tight range of uniform zircon Hf isotope compositions (εHf(1850) of ca. -9 to -12). This is consistent with its well-established crustal origin and indicates differentiation from a single melt that was initially efficiently homogenised. We propose that the heterogeneity in other isotopic systems, such as Pb, in early-emplaced impact melt at Sudbury is associated with volatility-related depletion during the impact cratering process. This depletion leaves the isotopic systems of more volatile elements more susceptible to contamination during post-impact assimilation of country rock, whereas the systems of more refractory elements preserve initial homogeneities. Zircon oxygen isotope compositions in the melt sheet are also restricted in range relative to those in the impacted target rocks. However, they display a marked offset approximately one-third up the melt sheet stratigraphy that is interpreted to be a result of post-impact assimilation of 18O-enirched rocks into the base of the cooling impact melt. Given that impact cratering was a more dominant process in the early history of the inner Solar System than it is today, and the possibility that impact melt sheets were sources of ex situ Hadean zircon grains, these findings may have significance for the interpretation of the early zircon Hf record. We speculate that apparent εHf-time arrays observed in the oldest terrestrial and lunar zircon datasets may be related to impact melting homogenising previously more diverse crust. We also show that spatially restricted partial melting of rocks buried beneath the superheated impact melt at Sudbury provided a zircon crystallising environment distinct to the impact melt sheet itself.

  5. Biomass preservation in impact melt ejecta

    Science.gov (United States)

    Howard, Kieren Torres; Bailey, Melanie J.; Berhanu, Deborah; Bland, Phil A.; Cressey, Gordon; Howard, Lauren E.; Jeynes, Chris; Matthewman, Richard; Martins, Zita; Sephton, Mark A.; Stolojan, Vlad; Verchovsky, Sasha

    2013-12-01

    Meteorites can have played a role in the delivery of the building blocks of life to Earth only if organic compounds are able to survive the high pressures and temperatures of an impact event. Although experimental impact studies have reported the survival of organic compounds, there are uncertainties in scaling experimental conditions to those of a meteorite impact on Earth and organic matter has not been found in highly shocked impact materials in a natural setting. Impact glass linked to the 1.2-km-diameter Darwin crater in western Tasmania is strewn over an area exceeding 400km2 and is thought to have been ejected by a meteorite impact about 800kyr ago into terrain consisting of rainforest and swamp. Here we use pyrolysis-gas chromatography-mass spectrometry to show that biomarkers representative of plant species in the local ecosystem--including cellulose, lignin, aliphatic biopolymer and protein remnants--survived the Darwin impact. We find that inside the impact glass the organic components are trapped in porous carbon spheres. We propose that the organic material was captured within impact melt and preserved when the melt quenched to glass, preventing organic decomposition since the impact. We suggest that organic material can survive capture and transport in products of extreme impact processing, at least for a Darwin-sized impact event.

  6. Mini-RF Observations of Lunar Impact Melt Flows

    Science.gov (United States)

    Carter, L. M.; Neish, C.; Bussey, B.; Spudis, P.; Robinson, M.; Patterson, W.; Cahill, J.; Heggy, E.; Raney, R. K.; Mini-Rf Team

    2010-12-01

    km diameter King crater (5° N, 120.5° E), melt from the King impact ponded in a previously existing depression. Mini-RF images show that some of the melt from this impact moved with a velocity that carried it past the melt pond, across the elevated rim of the pond, and away from the impact site towards the north. Finally, the 55 km diameter crater Aristillus (33.9° N, 1.2° E) has long and particularly thin impact melt flows that extend over 2 crater radii from the rim [Campbell et al. 2010]. In Mini-RF data, the Aristillus flow margins have a complex shape that was likely generated by the effects of topography on the moving melt. There is little change in backscatter cross-section and no evidence of channeling within the flow. Additional analysis of the radar polarimetric properties and comparisons with optical imagery will be useful in determining the surface textures and emplacement process for these and other impact melt flows.

  7. Melt pool modelling, simulation and experimental validation for SLM

    NARCIS (Netherlands)

    Wits, Wessel

    2017-01-01

    SLM parts are built by successively melting layers of powder in a powder bed. Process parameters are often optimized experimentally by laser scanning a number of single tracks and subsequently determining which settings lead to a good compromise between quality and build speed. However,

  8. Computationally efficient thermal-mechanical modelling of selective laser melting

    NARCIS (Netherlands)

    Yang, Y.; Ayas, C.; Brabazon, Dermot; Naher, Sumsun; Ul Ahad, Inam

    2017-01-01

    The Selective laser melting (SLM) is a powder based additive manufacturing (AM) method to produce high density metal parts with complex topology. However, part distortions and accompanying residual stresses deteriorates the mechanical reliability of SLM products. Modelling of the SLM process is

  9. Evolution of Shock Melt Compositions in Lunar Agglutinates

    Science.gov (United States)

    Vance, A. M.; Christoffersen, R.; Keller, L. P.

    2015-01-01

    Lunar agglutinates are aggregates of regolith grains fused together in a glassy matrix of shock melt produced during smaller-scale (mostly micrometeorite) impacts. Agglutinate formation is a key space weathering process under which the optically-active component of nanophase metallic Fe (npFe(sup 0)) is added to the lunar regolith. Here we have used energy-dispersive X-ray (EDX) compositional spectrum imaging in the SEM to quantify the chemical homogeneity of agglutinitic glass, correlate its homogeneity to its parent soil maturity, and identify the principle chemical components contributing to the shock melt compositional variations.

  10. Electrochemical Properties of Zirconium, Plutonium and Lanthanides in Fluoride Melts

    International Nuclear Information System (INIS)

    Zakirov, R.; Ignatiev, V.; Subbotin, V.; Toropov, A.

    2004-01-01

    Today the evaluation of pyrochemical treatment capability request more experimental data and demonstrations then what has been done up to now. Much more calculated and experimental results are available on a thermodynamic of electrochemical processes in chloride melts compared to fluoride ones. New experimental data on electrochemical properties of 60LiF-40NaF and 15LiF58NaF-27BeF 2 (mol. %) eutectic melts containing ZrF 4 , PuF 3 and LnF 3 (NdF 3 , LaF 3 , CeF 3 ) are presented. (authors)

  11. Dense Pure Tungsten Fabricated by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Dianzheng Wang

    2017-04-01

    Full Text Available Additive manufacturing using tungsten, a brittle material, is difficult because of its high melting point, thermal conductivity, and oxidation tendency. In this study, pure tungsten parts with densities of up to 18.53 g/cm3 (i.e., 96.0% of the theoretical density were fabricated by selective laser melting. In order to minimize balling effects, the raw polyhedral tungsten powders underwent a spheroidization process before laser consolidation. Compared with polyhedral powders, the spherical powders showed increased laser absorptivity and packing density, which helped in the formation of a continuous molten track and promoted densification.

  12. The Properties of Ammonium Dinitramine (ADN): Part 2: Melt Casting

    Science.gov (United States)

    Hahma, A.; Edvinsson, H.; Östmark, H.

    2010-04-01

    A melt casting technique for ammonium dinitramine (ADN) and ADN/aluminum was developed. ADN proved relatively easy to cast, when 1% of magnesium oxide was used as a stabilizer and crystallization kernels. Densities of ADN/MgO 99/1 were 92 to 97% of theoretical mean density (TMD) and those of ADN/Al/MgO 64/35/1 were between 95 and 99% of TMD. Sedimentation of Al in the melt was prevented and the particle wetting was ensured by selecting a suitable particle size for Al. No gelling agents or other additives were used. The casting process and factors influencing it are discussed.

  13. Melting of Uranium Metal Powders with Residual Salts

    International Nuclear Information System (INIS)

    Jin-Mok Hur; Dae-Seung Kang; Chung-Seok Seo

    2007-01-01

    The Advanced Spent Fuel Conditioning Process (ACP) of the Korea Atomic Energy Research Institute focuses on the conditioning of Pressurized Water Reactor spent oxide nuclear fuel. After the oxide reduction step of the ACP, the resultant metal powders containing ∼ 30 wt% residual LiCl-Li 2 O should be melted for a consolidation of the fine metal powders. In this study, we investigated the melting behaviors of uranium metal powders considering the effects of a LiCl-Li 2 O residual salt. (authors)

  14. Industrial opportunities of controlled melt flow during glass melting, part 1: Melt flow evaluation

    Czech Academy of Sciences Publication Activity Database

    Dyrčíková, Petra; Hrbek, Lukáš; Němec, Lubomír

    2014-01-01

    Roč. 58, č. 2 (2014), s. 111-117 ISSN 0862-5468 R&D Projects: GA TA ČR TA01010844 Institutional support: RVO:67985891 Keywords : glass melting * controlled flow * space utilization Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.435, year: 2014 http://www.ceramics-silikaty.cz/2014/pdf/2014_02_111.pdf

  15. Electrochemical Study on Ligand Substitution Reactions in Oxofluoro Boron Containing Melts

    DEFF Research Database (Denmark)

    Polyakova, L.P.; Bukatova, G.A.; Polyakov, E.G.

    1997-01-01

    Linear voltammetry was used for study of the ligand substitution reactions in the process of titration of FLINAK-KBF4, melt with different oxides. At molar ratio O/B=1 complexes BF4- which are characteristic for oxygenless melt transform into BOF2- Further increasing of O/B ratio up to 2 leads to...

  16. Preparation and melting of uranium from U3O8

    International Nuclear Information System (INIS)

    Hur, Jin-Mok; Choi, In-Kyu; Cho, Soo-Haeng; Jeong, Sang-Mun; Seo, Chung-Seok

    2008-01-01

    In this paper, we report on the preparation and melting of uranium in association with a spent nuclear fuel conditioning process. U 3 O 8 powder was electrochemically reduced in a mixture of molten LiCl-Li 2 O (∼3 wt.% of Li 2 O in LiCl) at 650 deg. C resulting in the formation of uranium and Li 2 O with a yield of >99%. When the powder of uranium with a residual LiCl-Li 2 O salt was heated in order to melt the metal, the uranium oxidation to UO 2 due to the reaction with Li 2 O was observed. We were able to synthesize FeU 6 by using a Fe based cathode during the U 3 O 8 reduction procedure. FeU 6 could be melted to below the temperatures where the oxidation of uranium by Li 2 O occurred. The idea of compound formation and melting is applicable to the melting and casting of a spent nuclear fuel which contains oxidative residual salts due to its conditioning in a molten salt

  17. Microstructure analysis of magnesium alloy melted by laser irradiation

    International Nuclear Information System (INIS)

    Liu, S.Y.; Hu, J.D.; Yang, Y.; Guo, Z.X.; Wang, H.Y.

    2005-01-01

    The effects of laser surface melting (LSM) on microstructure of magnesium alloy containing Al8.57%, Zn 0.68%, Mn0.15%, Ce0.52% were investigated. In the present work, a pulsed Nd:YAG laser was used to melt and rapidly solidify the surface of the magnesium alloy with the objective of changing microstructure and improving the corrosion resistance. The results indicate that laser-melted layer contains the finer dendrites and behaviors good resistance corrosion compared with the untreated layer. Furthermore, the absorption coefficient of the magnesium alloy has been estimated according to the numeral simulation of the thermal conditions. The formation process of fine microstructure in melted layers was investigated based on the experimental observation and the theoretical analysis. Some simulation results such as the re-solidification velocities are obtained. The phase constitutions of the melted layers determined by X-ray diffraction were β-Mg 17 Al 12 and α-Mg as well as some phases unidentified

  18. Inviscid melt spinning-IMS crystallization of amorphous alumina fibers

    Energy Technology Data Exchange (ETDEWEB)

    Wallenberger, F.T. (E.I. Du Pont De Nemours Co., Wilmington, DE (USA)); Dunn, S.A. (Univ. of Wisconsin, Madison (USA)); Weston, N.E.

    1990-04-01

    Experimental amorphous Al{sub 2}O{sub 3}CaO fibers (<80% Al{sub 2}O{sub 3}) which had been made by inviscid melt spinning (IMS) of low viscosity melts were found to retain up to 87% of their room temperature tensile strength at 750{degree}C (versus 25% for S-glass). The results suggest that the strength of these fibers is ultimately limited by their crystallization temperatures and that they might tolerate 100-200{degree}C higher temperatures than S-glass in comparable applications (e.g., in fiber reinforced composites). Some fibers were crystallized in a laboratory furnace. The crystalline phases of the resulting fibers were correlated with measured properties. The implications were applied to an analysis of a proposed process for redrawing inviscid melt spun (RIMS) fibers.

  19. Microstructure and mechanical properties of selective laser melted magnesium

    International Nuclear Information System (INIS)

    Ng, C.C.; Savalani, M.M.; Lau, M.L.; Man, H.C.

    2011-01-01

    The effects of laser processing parameters on the microstructure and mechanical properties of selective laser-melted magnesium were investigated. The results show that the microstructure characteristics of the laser-melted samples are dependent on the grain size of SLM magnesium. The grains in the molten zone coarsen as the laser energy density increases. In addition, the average hardness values of the molten zone decreases significantly with an increase of the laser energy densities and then decreased slowly at a relatively high laser energy density irrespective of mode of irradiation. The hardness value was obtained from 0.59 to 0.95 GPa and corresponding elastic modulus ranging from 27 to 33 GPa. The present selective laser-melted magnesium parts are promising for biomedical applications since the mechanical properties are more closely matched with human bone than other metallic biomaterials.

  20. Modeling of nuclear waste disposal by rock melting

    International Nuclear Information System (INIS)

    Heuze, F.E.

    1982-04-01

    Today, the favored option for disposal of high-level nuclear wastes is their burial in mined caverns. As an alternative, the concept of deep disposal by rock melting (DRM) also has received some attention. DRM entails the injection of waste, in a cavity or borehole, 2 to 3 kilometers down in the earth crust. Granitic rocks are the prime candidate medium. The high thermal loading initially will melt the rock surrounding the waste. Following resolidification, a rock/waste matrix is formed, which should provide isolation for many years. The complex thermal, mechanical, and hydraulic aspects of DRM can be studied best by means of numerical models. The models must accommodate the coupling of the physical processes involved, and the temperature dependency of the granite properties, some of which are subject to abrupt discontinuities, during α-β phase transition and melting. This paper outlines a strategy for such complex modeling

  1. Effect of cooling rate on crystallization in an aluminophosphosilicate melt

    DEFF Research Database (Denmark)

    Liu, S. J.; Zhang, Yanfei; Yue, Yuanzheng

    2011-01-01

    The effect of cooling rate on spontaneous crystallization behavior of an alumino-phospho-silicate melt is studied by means of differential scanning calorimetry, X-ray diffraction, scanning electron microscopy and viscometry. The cooling rates of 160, 2100 and 12000 K/s are attained by subjecting ......, the opalescence of the glass can be tuned by adjusting the cooling rate. This makes the production of opal glasses or transparent glass ceramics more efficient and energy saving, since the conventional isothermal treatment procedure can be left out....... the glass melt to the casting, pressing and fiber-drawing processes, respectively. Results show that phase separation occurs in the melt during cooling, and leads to the internal nucleation and opalescence in the studied glass. The degree of phase separation increases with decreasing the cooling rate. Hence...

  2. Formulation and Characterization of Solid Dispersion Prepared by Hot Melt Mixing: A Fast Screening Approach for Polymer Selection.

    Science.gov (United States)

    Enose, Arno A; Dasan, Priya K; Sivaramakrishnan, H; Shah, Sanket M

    2014-01-01

    Solid dispersion is molecular dispersion of drug in a polymer matrix which leads to improved solubility and hence better bioavailability. Solvent evaporation technique was employed to prepare films of different combinations of polymers, plasticizer, and a modal drug sulindac to narrow down on a few polymer-plasticizer-sulindac combinations. The sulindac-polymer-plasticizer combination that was stable with good film forming properties was processed by hot melt mixing, a technique close to hot melt extrusion, to predict its behavior in a hot melt extrusion process. Hot melt mixing is not a substitute to hot melt extrusion but is an aid in predicting the formation of molecularly dispersed form of a given set of drug-polymer-plasticizer combination in a hot melt extrusion process. The formulations were characterized by advanced techniques like optical microscopy, differential scanning calorimetry, hot stage microscopy, dynamic vapor sorption, and X-ray diffraction. Subsequently, the best drug-polymer-plasticizer combination obtained by hot melt mixing was subjected to hot melt extrusion process to validate the usefulness of hot melt mixing as a predictive tool in hot melt extrusion process.

  3. Dendrite Growth Kinetics in Undercooled Melts of Intermetallic Compounds

    Directory of Open Access Journals (Sweden)

    Dieter M. Herlach

    2015-09-01

    Full Text Available Solidification needs an undercooling to drive the solidification front. If large undercoolings are achieved, metastable solid materials are solidified from the undercooled melt. Containerless processing provides the conditions to achieve large undercoolings since heterogeneous nucleation on container walls is completely avoided. In the present contribution both electromagnetic and electrostatic levitation are applied. The velocity of rapidly advancing dendrites is measured as a function of undercooling by a High-Speed-Camera. The dendrite growth dynamics is investigated in undercooled melts of intermetallic compounds. The Al50Ni50 alloy is studied with respect to disorder trapping that leads to a disordered superlattice structure if the melt is undercooled beyond a critical undercooling. Disorder trapping is evidenced by in situ energy dispersive diffraction using synchrotron radiation of high intensity to record full diffraction pattern on levitated samples within a short time interval. Experiments on Ni2B using different processing techniques of varying the level of convection reveal convection-induced faceting of rapidly growing dendrites. Eventually, the growth velocity is measured in an undercooled melt of glass forming Cu50Zr50 alloy. A maximum in the growth velocity–undercooling relation is proved. This is understood by the fact that the temperature dependent diffusion coefficient counteracts the thermodynamic driving force for rapid growth if the temperature of the undercooled melt is approaching the temperature regime above the glass transition temperature. The analysis of this result allows for determining the activation energy of atomic attachment kinetics at the solid–liquid interface that is comparable to the activation energy of atomic diffusion as determined by independent measurements of the atomic diffusion in undercooled Cu50Zr50 alloy melt.

  4. Measuring melting capacity with calorimetry

    OpenAIRE

    Betten, Linda

    2014-01-01

    Road salting is an important aspect of winter maintenance. There has been an increase in the usage of salt in later years to keep the road safe and accessible. It is a desire to reduce the amount of salt due to environmental aspects. To achieve better practices for winter maintenance it is necessary to obtain more knowledge about the different properties of salt. The motivation for this thesis is to develop a better method for determining the melting capacity for salt, which is an important p...

  5. Fundamentals of twin-screw extrusion polymer melting: Common pitfalls and how to avoid them

    Science.gov (United States)

    Andersen, Paul

    2015-05-01

    The process for compounding engineered polymer formulations is comprised of several unit operations. These typically include, but are not limited to: feedstock introduction, polymer melt-mixing, distributive/dispersive mixing of minerals/fibers, removal of volatiles, and pressurization for discharge. While each unit operation has an impact on process productivity and the quality of the finished product, polymer melt-mixing has a significantly greater impact than the others. First, it consumes 50, 60 or higher percent of the total system energy. Second, it generates the highest radial as well as particle-particle interactive pressure of any unit operation. Third, the negative impact on the process of any design flaws in the melt-mixing configuration is transmitted downstream to all subsequent unit operations. For example, a melt-mixing design that is too intense may degrade the polymer while one that is too weak may result in excessive breakage of glass fiber being fed downstream due to the polymer solidifying on the glass fiber and subsequently being re-melted. Another example of the impact of an incorrect melt-mixing configuration would be excessive abrasive wear. Adhesive wear is also possible as well as deformation on both barrel wall and screw elements due to high radial forces. Additionally, non-melting material present during the melt-mixing process could be compacted into "briquettes" by the high radial pressure and would have to be dispersed by subsequent downstream unit operations. Other potential issues associated with a non-optimal melting section are pre-mature and incomplete melting. The former is more of a concern with melting of powder feed stock while the latter is more probable with feed stock comprised of a broad range of particle sizes. However, the consequence of both is to convey unmolten polymer beyond the melting section. While this may not be perceived as a significant issue for most processes, it is an issue if the sole purpose of the

  6. First experimental observations on melting and chemical modification of volcanic ash during lightning interaction.

    Science.gov (United States)

    Mueller, S P; Helo, C; Keller, F; Taddeucci, J; Castro, J M

    2018-01-23

    Electrification in volcanic ash plumes often leads to syn-eruptive lightning discharges. High temperatures in and around lightning plasma channels have the potential to chemically alter, re-melt, and possibly volatilize ash fragments in the eruption cloud. In this study, we experimentally simulate temperature conditions of volcanic lightning in the laboratory, and systematically investigate the effects of rapid melting on the morphology and chemical composition of ash. Samples of different size and composition are ejected towards an artificially generated electrical arc. Post-experiment ash morphologies include fully melted spheres, partially melted particles, agglomerates, and vesiculated particles. High-speed imaging reveals various processes occurring during the short lightning-ash interactions, such as particle melting and rounding, foaming, and explosive particle fragmentation. Chemical analyses of the flash-melted particles reveal considerable bulk loss of Cl, S, P and Na through thermal vaporization. Element distribution patterns suggest convection as a key process of element transport from the interior of the melt droplet to rim where volatiles are lost. Modeling the degree of sodium loss delivers maximum melt temperatures between 3290 and 3490 K. Our results imply that natural lighting strikes may be an important agent of syn-eruptive morphological and chemical processing of volcanic ash.

  7. Pathway from subducting slab to surface for melt and fluids beneath Mount Rainier.

    Science.gov (United States)

    McGary, R Shane; Evans, Rob L; Wannamaker, Philip E; Elsenbeck, Jimmy; Rondenay, Stéphane

    2014-07-17

    Convergent margin volcanism originates with partial melting, primarily of the upper mantle, into which the subducting slab descends. Melting of this material can occur in one of two ways. The flow induced in the mantle by the slab can result in upwelling and melting through adiabatic decompression. Alternatively, fluids released from the descending slab through dehydration reactions can migrate into the hot mantle wedge, inducing melting by lowering the solidus temperature. The two mechanisms are not mutually exclusive. In either case, the buoyant melts make their way towards the surface to reside in the crust or to be extruded as lava. Here we use magnetotelluric data collected across the central state of Washington, USA, to image the complete pathway for the fluid-melt phase. By incorporating constraints from a collocated seismic study into the magnetotelluric inversion process, we obtain superior constraints on the fluids and melt in a subduction setting. Specifically, we are able to identify and connect fluid release at or near the top of the slab, migration of fluids into the overlying mantle wedge, melting in the wedge, and transport of the melt/fluid phase to a reservoir in the crust beneath Mt Rainier.

  8. Ex-Vessel Core Melt Modeling Comparison between MELTSPREAD-CORQUENCH and MELCOR 2.1

    Energy Technology Data Exchange (ETDEWEB)

    Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Farmer, Mitchell [Argonne National Lab. (ANL), Argonne, IL (United States); Francis, Matthew W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-03-01

    System-level code analyses by both United States and international researchers predict major core melting, bottom head failure, and corium-concrete interaction for Fukushima Daiichi Unit 1 (1F1). Although system codes such as MELCOR and MAAP are capable of capturing a wide range of accident phenomena, they currently do not contain detailed models for evaluating some ex-vessel core melt behavior. However, specialized codes containing more detailed modeling are available for melt spreading such as MELTSPREAD as well as long-term molten corium-concrete interaction (MCCI) and debris coolability such as CORQUENCH. In a preceding study, Enhanced Ex-Vessel Analysis for Fukushima Daiichi Unit 1: Melt Spreading and Core-Concrete Interaction Analyses with MELTSPREAD and CORQUENCH, the MELTSPREAD-CORQUENCH codes predicted the 1F1 core melt readily cooled in contrast to predictions by MELCOR. The user community has taken notice and is in the process of updating their systems codes; specifically MAAP and MELCOR, to improve and reduce conservatism in their ex-vessel core melt models. This report investigates why the MELCOR v2.1 code, compared to the MELTSPREAD and CORQUENCH 3.03 codes, yield differing predictions of ex-vessel melt progression. To accomplish this, the differences in the treatment of the ex-vessel melt with respect to melt spreading and long-term coolability are examined. The differences in modeling approaches are summarized, and a comparison of example code predictions is provided.

  9. Viscosity model for aluminosilicate melt

    Directory of Open Access Journals (Sweden)

    Zhang G.H.

    2012-01-01

    Full Text Available The structurally based viscosity model proposed in our previous study is extended to include more components, e.g. SiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O and K2O. A simple method is proposed to calculate the numbers of different types of oxygen ions classified by the different cations they bonded with, which is used to characterize the influence of composition on viscosity. When dealing with the aluminosilicate melts containing several basic oxides, the priority order is established for different cations for charge compensating Al3+ ions, according to the coulombic force between cation and oxygen anion. It is indicated that basic oxides have two paradox influences on viscosity: basic oxide with a higher basicity decreases viscosity more greatly by forming weaker non-bridging oxygen bond; while it increases viscosity more greatly by forming stronger bridging oxygen bond in tetrahedron after charge compensating Al3+ ion. The present model can extrapolate its application range to the system without SiO2. Furthermore, it could also give a satisfy interpretation to the abnormal phenomenon that viscosity increases when adding K2O to CaO-Al2O3-SiO2 melt within a certain composition range.

  10. Phenomenological Studies on Melt-Structure-Water Interactions (MSWI) during Postulated Severe Accidents

    International Nuclear Information System (INIS)

    Sehgal, B.R.; Park, H.S.; Giri, A.; Karbojian, A.; Jasiulevicius, A.; Hansson, R.C.; Chikkanagoudar, U.; Shiferaw, D.; Stepanyan, A.

    2004-01-01

    This is the annual report for the work performed in year 2003 in the research project 'Melt-Structure-Water Interactions (MSWI) During Severe Accidents in LWRs', under the auspices of the APRI Project, jointly funded by SKI, HSK, and the Swedish and Finnish power companies. The emphasis of the work was placed on phenomena and parameters, which govern the droplet fragmentation in steam explosions, in-vessel and ex-vessel melt/debris coolability, melt pool convection, and the thermal and mechanical loadings of a pressure vessel during melt-vessel interaction. Most research projects in 2002, such as the COMECO, POMECO and MISTEE programs, were continued. An analysis of the FOREVER experiments using the RELAP code to investigate the melt coolability, bubble dynamics and bubble stability to investigate the dynamic behavior of vapor bubble during steam explosions and associated melt fragmentation, quenching boiling experiment to investigate the thermal behavior of single melt droplet were newly initiated. The SIMECO experiment to investigate the three-layer melt pool convection was restarted. The experimental facilities for these projects were fully functional during year 2003. Many of the investigations performed during the course of the MSWI project have produced papers, which have been published in the proceedings of technical meetings and Journals. Significant technical advances were achieved during the course of these studies. These were: A series of experiments on single drop steam explosions was performed to investigate the fine fragmentation process of a metallic melt drop in various thermal conditions. For the first time, transient fine fragmentation process of a melt drop during explosion phase of a steam explosion was visualized continuously and quantified. Different triggering behavior with respect to the coolant subcooling was observed. The analyses on bubble dynamics during a single drop steam explosion and vapor bubble stability estimated the dynamic

  11. Multiscale Models of Melting Arctic Sea Ice

    Science.gov (United States)

    2014-09-30

    Sea ice reflectance or albedo , a key parameter in climate modeling, is primarily determined by melt pond and ice floe configurations. Ice - albedo ...determine their albedo - a key parameter in climate modeling. Here we explore the possibility of a conceptual sea ice climate model passing through a...bifurcation points. Ising model for melt ponds on Arctic sea ice Y. Ma, I. Sudakov, and K. M. Golden Abstract: The albedo of melting

  12. Sound propagation in selenium and tellurium melts

    International Nuclear Information System (INIS)

    Glazov, V.M.; Kim, S.G.; Sulejmenov, T.

    1989-01-01

    Methods, that under similar frequences of ten MHz and using one sample permit to study temperature dependences and propagation velocities, the absorption coefficient of the sound in melts, are described. As a result studying selenium and tellurium melts intricate polytherms of sound propagation velocity and absorption coefficient, that are interpreted usiung representations on breaking chains in associated liquid(selenium) and dissolution of short chains in the melt(tellurium) atomic matrix, are constructed

  13. Fugacity ratio estimations for high-melting rigid aromatic compounds.

    Science.gov (United States)

    Van Noort, Paul C M

    2004-07-01

    Prediction of the environmental fate of organic compounds requires knowledge of their tendency to stay in the gas and water phase. Vapor pressure and aqueous solubility are commonly used descriptors for these processes. Depending on the type of distribution process, values for either the pure solid state or the (subcooled) liquid state have to be used. Values for the (subcooled) liquid state can be calculated from those for the solid state, and vice versa, using the fugacity ratio. Fugacity ratios are usually calculated from the entropy of fusion and the melting point. For polycyclic aromatic hydrocarbons, chlorobenzenes, chlorodibenzofuranes, and chlorodibenzo(p)dioxins, fugacity ratios calculated using experimental entropies of fusion were systematically less than those obtained from a thermodynamically more rigorous approach using heat capacity data. The deviation was more than 1 order of magnitude at the highest melting point. The use of a universal value for the entropy of fusion of 56 J/molK resulted in either over or underestimation by up to more than 1 order of magnitude. A simple correction factor, based on the melting point only, was derived. This correction factor allowed the fugacity ratios to be estimated from experimental entropies of fusion and melting point with an accuracy better than 0.1-0.2 log units. Copyright 2004 Elsevier Ltd.

  14. Surface melting of deuterium hydride thick films

    OpenAIRE

    Zeppenfeld, P.; Bienfait, M.; Feng Chuan Liu,; Vilches, O.E.; Coddens, G.

    1990-01-01

    Quasi-elastic neutron scattering has been used to measure, below the bulk melting temperature, the thickness and the diffusion coefficient of the mobile surface layer of 8 and 10 layer thick films of deuterium hydride (HD) condensed on MgO(100). The measurements show that the close-packed surface of solid HD surface melts gradually, with the thickness of the melted layer increasing from 0.5 to 6 molecular layers as the temperature rises from 4 K to 0.05 K below the bulk melting temperature. T...

  15. Investigation of Tantalum Recycling by Electron Beam Melting

    Directory of Open Access Journals (Sweden)

    Katia Vutova

    2016-11-01

    Full Text Available Investigations are carried out and obtained experimental and theoretical data for tantalum scrap recycling by electron beam melting (EBM is presented in this paper. Different thermal treatment process conditions are realized and results are discussed. A chemical analysis is performed and refining mechanisms for electron beam (EB refining of Ta are discussed. For the performed experiments the best purification of Ta (99.96 is obtained at 21.6 kW beam power for a melting time of 3 min. A statistical approach is applied for estimation of the material losses and the liquid pool characteristics based on experimentally-obtained data. The aim is to improve the EBM and choosing optimal process conditions, depending on the concrete characteristic requirements. Model-based quality optimization of electron beam melting and refining (EBMR processes of Ta is considered related to the optimization of the molten pool parameters, connected to the occurring refining processes, and to minimal material losses. Optimization of the process of EBM of Ta is based on overall criteria, giving compromised solutions, depending on the requirements concerning the quality of the performed products. The accumulated data, the obtained results, and the optimization statistical approach allow us to formulate requirements on the process parameters.

  16. Progress in melt-texturing of YBCO superconductors

    International Nuclear Information System (INIS)

    Salama, K.; Lee, D.F.; Selvamanickam, V.

    1993-01-01

    Since the discovery of high temperature superconductors (HTS), tremendous efforts have been expanded toward the improvement of these materials. Due to the weak-link problem associated with grain boundaries, sintered bulk HTS possess a transport critical current density (J c ) on the order of 10 2 -10 3 A/cm 2 at 77 K. While these sintered superconductors may be utilized in low current applications, novel processing methods have to be developed to obtain HTS that can sustain high currents. Melt-texturing of HTS was found to result in a high degree of grain orientation, and is presently the most prominent processing method used to manufacture bulk YBa 2 Cu 3 O x (123) with superior transport and magnetic properties. In this review paper, various melt-texturing methods will be discussed, and the variation in J c with processing will be presented. (orig.)

  17. Melt rheology and its applications in the plastics industry

    CERN Document Server

    Dealy, John M

    2013-01-01

    This is the second edition of Melt Rheology and its Role in Plastics Processing, although the title has changed to reflect its broadened scope. Advances in the recent years in rheometer technology and polymer science have greatly enhanced the usefulness of rheology in the plastics industry. It is now possible to design polymers having specific molecular structures and to predict the flow properties of melts having those structures. In addition, rheological properties now provide more precise information about molecular structure. This book provides all the information that is needed for the intelligent application of rheology in the development of new polymers, the determination of molecular structure and the correlation of processability with laboratory test data. Theory and equations are limited to what is essential for the use of rheology in the characterization of polymers, the development of new plastics materials and the prediction of plastics processing behavior. The emphasis is on information that wil...

  18. Grain boundary melting in ice

    Science.gov (United States)

    Thomson, E. S.; Hansen-Goos, Hendrik; Wettlaufer, J. S.; Wilen, L. A.

    2013-03-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentration. Although we understand that the interfacial surface charge densities qs and solute concentrations can potentially dominate the film thickness, we cannot directly measure them within a given grain boundary. Therefore, as a framework for interpreting the data we consider two appropriate qs dependent limits; one is dominated by the colligative effect and other is dominated by electrostatic interactions.

  19. Electrolysis of simulated lunar melts

    Science.gov (United States)

    Lewis, R. H.; Lindstrom, D. J.; Haskin, L. A.

    1985-01-01

    Electrolysis of molten lunar soil or rock is examined as an attractive means of wresting useful raw materials from lunar rocks. It requires only hat to melt the soil or rock and electricity to electrolyze it, and both can be developed from solar power. The conductivities of the simple silicate diopside, Mg CaSi2O6 were measured. Iron oxide was added to determine the effect on conductivity. The iron brought about substantial electronic conduction. The conductivities of simulated lunar lavas were measured. The simulated basalt had an AC conductivity nearly a fctor of two higher than that of diopside, reflecting the basalt's slightly higher total concentration of the 2+ ions Ca, Mg, and Fe that are the dominant charge carriers. Electrolysis was shown to be about 30% efficient for the basalt composition.

  20. Review of selective laser melting: Materials and applications

    International Nuclear Information System (INIS)

    Yap, C. Y.; Chua, C. K.; Liu, Z. H.; Zhang, D. Q.; Loh, L. E.; Sing, S. L.; Dong, Z. L.

    2015-01-01

    Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following areas: (a) applications of SLM materials and (b) mechanical properties of SLM parts achieved in research publications. The review is not meant to put a ceiling on the capabilities of the SLM process but to enable readers to have an overview on the material properties achieved by the SLM process so far. Trends in research of SLM are also elaborated in the last section

  1. Reaction of soda-lime-silica glass melt with water vapour at melting temperatures

    Czech Academy of Sciences Publication Activity Database

    Vernerová, Miroslava; Kloužek, Jaroslav; Němec, Lubomír

    2015-01-01

    Roč. 416, MAY 15 (2015), s. 21-30 ISSN 0022-3093 R&D Projects: GA TA ČR TA01010844 Institutional support: RVO:67985891 Keywords : glass melt * sulfate * water vapour * bubble nucleation * melt foaming * glass melting Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.825, year: 2015

  2. Partitioning ratio of depleted uranium during a melt decontamination by arc melting

    International Nuclear Information System (INIS)

    Min, Byeong Yeon; Choi, Wang Kyu; Oh, Won Zin; Jung, Chong Hun

    2008-01-01

    In a study of the optimum operational condition for a melting decontamination, the effects of the basicity, slag type and slag composition on the distribution of depleted uranium were investigated for radioactively contaminated metallic wastes of iron-based metals such as stainless steel (SUS 304L) in a direct current graphite arc furnace. Most of the depleted uranium was easily moved into the slag from the radioactive metal waste. The partitioning ratio of the depleted uranium was influenced by the amount of added slag former and the slag basicity. The composition of the slag former used to capture contaminants such as depleted uranium during the melt decontamination process generally consists of silica (SiO 2 ), calcium oxide (CaO) and aluminum oxide (Al 2 O 3 ). Furthermore, calcium fluoride (CaF 2 ), magnesium oxide (MgO), and ferric oxide (Fe 2 O 3 ) were added to increase the slag fluidity and oxidative potential. The partitioning ratio of the depleted uranium was increased as the amount of slag former was increased. Up to 97% of the depleted uranium was captured between the ingot phase and the slag phase. The partitioning ratio of the uranium was considerably dependent on the basicity and composition of the slag. The optimum condition for the removal of the depleted uranium was a basicity level of about 1.5. The partitioning ratio of uranium was high, exceeding 5.5x10 3 . The slag formers containing calcium fluoride (CaF 2 ) and a high amount of silica proved to be more effective for a melt decontamination of stainless steel wastes contaminated with depleted uranium

  3. Experimental Investigation of the Viscosity of Iron-rich Silicate Melts under Pressure

    Science.gov (United States)

    Edwards, P. M.; Lesher, C. E.; Pommier, A.; O'Dwyer Brown, L.

    2017-12-01

    The transport properties of silicate melts govern diffusive flow of momentum, heat, and mass in the interior of terrestrial planets. In particular, constraining melt viscosity is critical for dynamic modeling of igneous processes and is thus key to our understanding of magma convection and mixing, melt migration in the mantle, and crystal-liquid fractionation. Among the different constituents of silicate melts, iron is of significant importance as it highly influences some of their properties, such as surface tension, compressibility, and density. We present an experimental study of the viscosity of natural and synthetic iron-rich silicate melts under pressure. In situ falling-sphere measurements of viscosity have been conducted on hedenbergite (CaFeSi2O6) and iron-rich peridotite melts from 1 to 7 GPa and at temperatures between 1750 and 2100 K, using the multi-anvil apparatus at the GSECARS beamline at the Advanced Photon Source, Argonne National Lab. We used double reservoir capsules, with the bottom reservoir containing the sample, while a more refractory material is placed in the upper reservoir (e.g., diopside, enstatite, forsterite). This configuration allows the fall of two rhenium spheres across the sample at different temperatures. Melt viscosity is calculated using Stokes' law and the terminal velocity of the spheres. We observe that melt viscosity slightly decreases with increasing temperature and increasing pressure: for instance, the viscosity of the hedenbergite melt decreases from 1.26 Pa•s to 0.43 Pa•s over the 1 - 3.5 GPa pressure range and between 1820 and 1930 K. Our experimental data are used to develop a viscosity model of iron-rich silicate melts under pressure. Results will be compared with previous viscosity works on iron-free and iron-bearing silicate liquids in order to discuss the effect of iron on melt viscosity and structure at pressure and temperature conditions relevant to terrestrial mantles.

  4. Premature melt solidification during mold filling and its influence on the as-cast structure

    Science.gov (United States)

    Wu, M.; Ahmadein, M.; Ludwig, A.

    2018-03-01

    Premature melt solidification is the solidification of a melt during mold filling. In this study, a numerical model is used to analyze the influence of the pouring process on the premature solidification. The numerical model considers three phases, namely, air, melt, and equiaxed crystals. The crystals are assumed to have originated from the heterogeneous nucleation in the undercooled melt resulting from the first contact of the melt with the cold mold during pouring. The transport of the crystals by the melt flow, in accordance with the socalled "big bang" theory, is considered. The crystals are assumed globular in morphology and capable of growing according to the local constitutional undercooling. These crystals can also be remelted by mixing with the superheated melt. As the modeling results, the evolutionary trends of the number density of the crystals and the volume fraction of the solid crystals in the melt during pouring are presented. The calculated number density of the crystals and the volume fraction of the solid crystals in the melt at the end of pouring are used as the initial conditions for the subsequent solidification simulation of the evolution of the as-cast structure. A five-phase volume-average model for mixed columnar-equiaxed solidification is used for the solidification simulation. An improved agreement between the simulation and experimental results is achieved by considering the effect of premature melt solidification during mold filling. Finally, the influences of pouring parameters, namely, pouring temperature, initial mold temperature, and pouring rate, on the premature melt solidification are discussed.

  5. High Efficiency, High Output Plastic Melt Waste Compactor (HEHO-PMWC), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop processes and waste heat recovery techniques to be incorporated into the existing Plastic Melt Waste Compactor (PMWC) to increase...

  6. Numerical study to represent non-isothermal melt-crystallization kinetics at laser-powder cladding

    CSIR Research Space (South Africa)

    Niziev, VG

    2013-04-01

    Full Text Available The study of laser-powder cladding process subject to heat transfer, melting and crystallization kinetics has been carried out numerically and experimentally. The Kolmogorov-Avrami equation was applied to describe the kinetics of the phase...

  7. Location specific solidification microstructure control in electron beam melting of Ti-6Al-4V

    Energy Technology Data Exchange (ETDEWEB)

    Narra, Sneha P.; Cunningham, Ross; Beuth, Jack; Rollett, Anthony D.

    2018-01-01

    Relationships between prior beta grain size in solidified Ti-6Al-4V and melting process parameters in the Electron Beam Melting (EBM) process are investigated. Samples are built by varying a machine-dependent proprietary speed function to cover the process space. Optical microscopy is used to measure prior beta grain widths and assess the number of prior beta grains present in a melt pool in the raster region of the build. Despite the complicated evolution of beta grain sizes, the beta grain width scales with melt pool width. The resulting understanding of the relationship between primary machine variables and prior beta grain widths is a key step toward enabling the location specific control of as-built microstructure in the EBM process. Control of grain width in separate specimens and within a single specimen is demonstrated.

  8. Effects of Process Conditions on the Mechanical Behavior of Aluminium Wrought Alloy EN AW-2219 (AlCu6Mn Additively Manufactured by Laser Beam Melting in Powder Bed

    Directory of Open Access Journals (Sweden)

    Michael Cornelius Hermann Karg

    2017-01-01

    Full Text Available Additive manufacturing is especially suitable for complex-shaped 3D parts with integrated and optimized functionality realized by filigree geometries. Such designs benefit from low safety factors in mechanical layout. This demands ductile materials that reduce stress peaks by predictable plastic deformation instead of failure. Al–Cu wrought alloys are established materials meeting this requirement. Additionally, they provide high specific strengths. As the designation “Wrought Alloys” implies, they are intended for manufacturing by hot or cold working. When cast or welded, they are prone to solidification cracks. Al–Si fillers can alleviate this, but impair ductility. Being closely related to welding, Laser Beam Melting in Powder Bed (LBM of Al–Cu wrought alloys like EN AW-2219 can be considered challenging. In LBM of aluminium alloys, only easily-weldable Al–Si casting alloys have succeeded commercially today. This article discusses the influences of boundary conditions during LBM of EN AW-2219 on sample porosity and tensile test results, supported by metallographic microsections and fractography. Load direction was varied relative to LBM build-up direction. T6 heat treatment was applied to half of the samples. Pronounced anisotropy was observed. Remarkably, elongation at break of T6 specimens loaded along the build-up direction exceeded the values from literature for conventionally manufactured EN AW-2219 by a factor of two.

  9. Melt sonoquenching: an affective process to obtain new hybrid material and achieve enhanced electrochromic performances based on V{sub 2}O{sub 5}/2,4,5-tris(1-methyl- 4-pyridinium)-imidazolide tetrafluoroborate nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Renato S. de; Goulart, Juliana da S.; Miranda, Fabio S.; Ponzio, Eduardo A., E-mail: eaponzio@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Quimica

    2014-03-15

    Hybrid electrochromic materials are a very important class of compounds, because they enable new and/or better optical and electrochemical properties to be unfolded. This paper reports the synthesis of the new V{sub 2}O{sub 5}.1.26H{sub 2}O([C{sub 3}N{sub 2}(C{sub 6}H{sub 7}N){sub 3}]){sub 0.07} using the combination of two traditional methods, melting quenching and sonochemistry. The new material was characterized by several methods in order to verify the physical and chemical characteristics and its possible use as an electrochromic electrode. The organic guest provokes an interlayer spacing decrease of the inorganic matrix and the electrostatic interaction between the oxo groups of the V{sub 2}O{sub 5} matrix and the pyridinium rings of the organic guest demonstrate a strong interaction. The new hybrid nanostructure presented good reversibility and cyclability during 50 cycles, electrochromic efficiency of 22 cm{sup 2} C{sup -1} (410 nm) and 96 % color retention after 50 cycles of color changing. (author)'.

  10. Permeability and 3-D melt geometry in shear-induced high melt fraction conduits

    Science.gov (United States)

    Zhu, W.; Cordonnier, B.; Qi, C.; Kohlstedt, D. L.

    2017-12-01

    Observations of dunite channels in ophiolites and uranium-series disequilibria in mid-ocean ridge basalt suggest that melt transport in the upper mantle beneath mid-ocean ridges is strongly channelized. Formation of high melt fraction conduits could result from mechanical shear, pyroxene dissolution, and lithological partitioning. Deformation experiments (e.g. Holtzman et al., 2003) demonstrate that shear stress causes initially homogeneously distributed melt to segregate into an array of melt-rich bands, flanked by melt-depleted regions. At the same average melt fraction, the permeability of high melt fraction conduits could be orders of magnitude higher than that of their homogenous counterparts. However, it is difficult to determine the permeability of melt-rich bands. Using X-ray synchrotron microtomography, we obtained high-resolution images of 3-dimensional (3-D) melt distribution in a partially molten rock containing shear-induced high melt fraction conduits. Sample CQ0705, an olivine-alkali basalt aggregate with a nominal melt fraction of 4%, was deformed in torsion at a temperature of 1473 K and a confining pressure of 300 MPa to a shear strain of 13.3. A sub-volume of CQ0705 encompassing 3-4 melt-rich bands was imaged. Microtomography data were reduced to binary form so that solid olivine is distinguishable from basalt glass. At a spatial resolution of 160 nm, the 3-D images reveal the shape and connectedness of melt pockets in the melt-rich bands. Thin melt channels formed at grain edges are connected at large melt nodes at grain corners. Initial data analysis shows a clear preferred orientation of melt pockets alignment subparallel to the melt-rich band. We use the experimentally determined geometrical parameters of melt topology to create a digital rock with identical 3-D microstructures. Stokes flow simulations are conducted on the digital rock to obtain the permeability tensor. Using this digital rock physics approach, we determine how deformation

  11. Interaction between SiO2 and a KF-KCl-K2SiF6 Melt.

    Science.gov (United States)

    Zaykov, Yurii P; Isakov, Andrey V; Zakiryanova, Irina D; Reznitskikh, Olga G; Chemezov, Oleg V; Redkin, Alexander A

    2014-02-13

    The solubility mechanism of silica in a fluoride-chloride melt has been determined in situ using Raman spectroscopy. The spectroscopy data revealed that the silica solubility process involved Si-O bond breakage and Si-F bond formation. The process results in the formation of silicate complexes, fluorine-bearing silicate complexes, and silicon tetrafluoride in the melt. Mass spectrometry of the vapor phase over the KF-KCl-K2SiF6 and KF-KCl-K2SiF6-SiO2 melts and differential scanning calorimetry coupled with thermal gravimetric analysis of these melts were performed to verify the silica solubility mechanism.

  12. Investigation on Melt-Structure-Water Interactions (MSWI) during severe accidents

    International Nuclear Information System (INIS)

    Sehgal, B.R.; Yang, Z.L.; Dinh, T.N.; Nourgaliev, R.R.; Bui, V.A.; Haraldsson, H.O.; Li, H.X.; Konovakhin, M.; Paladino, D.; Leung, W.H

    1999-08-01

    This report is the final report for the work performed in 1998 in the research project Melt Structure Water Interactions (MSWI), under the auspices of the APRI Project, jointly funded by SKI, HSK, USNRC and the Swedish and Finnish power companies. The present report describes results of advanced analytical and experimental studies concerning melt-water-structure interactions during the course of a hypothetical severe core meltdown accident in a light water reactor (LWR). Emphasis has been placed on phenomena and properties which govern the fragmentation and breakup of melt jets and droplets, melt spreading and coolability, and thermal and mechanical loadings of a pressure vessel during melt-vessel interaction. Many of the investigations performed in support of this project have produced papers which have been published in the proceedings of technical meetings. A short summary of the results achieved in these papers is provided in this overview. Both experimental and analytical studies were performed to improve knowledge about phenomena of melt-structure-water interactions. We believe that significant technical advances have been achieved during the course of these studies. It was found that: the solidification has a strong effect on the drop deformation and breakup. Initially appearing at the drop surface and, later, thickening inwards, the solid crust layer dampens the instability waves on the drop surface and, therefore, hinders drop deformation and breakup. The drop thermal properties also affect the thermal behavior of the drop and, therefore, have impact on its deformation behavior. The jet fragmentation process is a function of many related phenomena. The fragmentation rate depends not only on the traditional parameters, e.g. the Weber number, but also on the melt physical properties, which change as the melt cools down from the liquidus to the solidus temperature. Additionally, the crust formed on the surface of the melt jet will also reduce the propensity

  13. Nucleation kinetics of ɛ-caprolactam melts in the presence of water impurity

    Science.gov (United States)

    Bouropoulos, Nicolaos Ch.; Kontoyannis, Christos G.; Koutsoukos, Petros G.

    1997-02-01

    The nucleation of ɛ-caprolactam in melts containing water impurities between 3% and 7% w/w was investigated in a batch reactor monitoring melt temperature. The induction times preceding the formation of ɛ-caprolactam nuclei were inversely proportional to the melt supersaturation and a threshold in the supersaturation of about 6% was found for homogenous nucleation. The interfacial tensions calculated using the classical nucleation theory ranged between 0.8 and 1.5 mJ m -2 for water content of 3%-7%, respectively. The concomitant increase of the size of the critical nucleus suggested that water inhibits the process of nucleation of ɛ-caprolactam in melts containing water impurity. This conclusion was further confirmed for the rates of crystal growth of the ɛ-caprolactam in the melts measured from the rates of temperature increase with time.

  14. Study of slag content and properties after plasma melting of incineration ash

    Science.gov (United States)

    Park, Hyun-Seo

    2011-06-01

    The paper presents the investigation of plasma melting of the mixed bottom and fly incineration ash at various mixing ratios of the components. Chemical compound of the bottom and fly ash as well as the slag after its melting was analyzed by different methods, and the content of toxic components in them was determined. It is demonstrated that the direct disposal of the fly and bottom incineration ash may cause dioxin and heavy metal contamination of the environment. The influence of melted ash basicity on the resulting slag compound was studied. The mass balance of the melting process was defined. The tests were performed to determine the heavy-metals leaching from the ash and slag. It is also shown that the slag after plasma melting is dioxin-free and environmentally friendly.

  15. Investigation on Melt-Structure-Water Interactions (MSWI) during severe accidents

    Energy Technology Data Exchange (ETDEWEB)

    Sehgal, B.R.; Yang, Z.L.; Dinh, T.N.; Nourgaliev, R.R.; Bui, V.A.; Haraldsson, H.O.; Li, H.X.; Konovakhin, M.; Paladino, D.; Leung, W.H [Royal Inst. of Tech., Stockholm (Sweden). Div. of Nuclear Power Safety

    1999-08-01

    This report is the final report for the work performed in 1998 in the research project Melt Structure Water Interactions (MSWI), under the auspices of the APRI Project, jointly funded by SKI, HSK, USNRC and the Swedish and Finnish power companies. The present report describes results of advanced analytical and experimental studies concerning melt-water-structure interactions during the course of a hypothetical severe core meltdown accident in a light water reactor (LWR). Emphasis has been placed on phenomena and properties which govern the fragmentation and breakup of melt jets and droplets, melt spreading and coolability, and thermal and mechanical loadings of a pressure vessel during melt-vessel interaction. Many of the investigations performed in support of this project have produced papers which have been published in the proceedings of technical meetings. A short summary of the results achieved in these papers is provided in this overview. Both experimental and analytical studies were performed to improve knowledge about phenomena of melt-structure-water interactions. We believe that significant technical advances have been achieved during the course of these studies. It was found that: the solidification has a strong effect on the drop deformation and breakup. Initially appearing at the drop surface and, later, thickening inwards, the solid crust layer dampens the instability waves on the drop surface and, therefore, hinders drop deformation and breakup. The drop thermal properties also affect the thermal behavior of the drop and, therefore, have impact on its deformation behavior. The jet fragmentation process is a function of many related phenomena. The fragmentation rate depends not only on the traditional parameters, e.g. the Weber number, but also on the melt physical properties, which change as the melt cools down from the liquidus to the solidus temperature. Additionally, the crust formed on the surface of the melt jet will also reduce the propensity

  16. Heat transfer model and finite element formulation for simulation of selective laser melting

    Science.gov (United States)

    Roy, Souvik; Juha, Mario; Shephard, Mark S.; Maniatty, Antoinette M.

    2017-10-01

    A novel approach and finite element formulation for modeling the melting, consolidation, and re-solidification process that occurs in selective laser melting additive manufacturing is presented. Two state variables are introduced to track the phase (melt/solid) and the degree of consolidation (powder/fully dense). The effect of the consolidation on the absorption of the laser energy into the material as it transforms from a porous powder to a dense melt is considered. A Lagrangian finite element formulation, which solves the governing equations on the unconsolidated reference configuration is derived, which naturally considers the effect of the changing geometry as the powder melts without needing to update the simulation domain. The finite element model is implemented into a general-purpose parallel finite element solver. Results are presented comparing to experimental results in the literature for a single laser track with good agreement. Predictions for a spiral laser pattern are also shown.

  17. Disordering and Melting of Aluminum Surfaces

    DEFF Research Database (Denmark)

    Stoltze, Per; Nørskov, Jens Kehlet; Landman, U.

    1988-01-01

    We report on a molecular-dynamics simulation of an Al(110) surface using the effective-medium theory to describe the interatomic interactions. The surface region is found to start melting ≅200 K below the bulk melting temperature with a gradual increase in the thickness of the disordered layer as...

  18. Recent Changes in the Arctic Melt Season

    Science.gov (United States)

    Stroeve, Julienne; Markus, Thorsten; Meier, Walter N.; Miller, Jeff

    2007-01-01

    Melt-season duration, melt-onset and freeze-up dates are derived from satellite passive microwave data and analyzed from 1979 to 2005 over Arctic sea ice. Results indicate a shift towards a longer melt season, particularly north of Alaska and Siberia, corresponding to large retreats of sea ice observed in these regions. Although there is large interannual and regional variability in the length of the melt season, the Arctic is experiencing an overall lengthening of the melt season at a rate of about 2 weeks decade(sup -1). In fact, all regions in the Arctic (except for the central Arctic) have statistically significant (at the 99% level or higher) longer melt seasons by greater than 1 week decade(sup -1). The central Arctic shows a statistically significant trend (at the 98% level) of 5.4 days decade(sup -1). In 2005 the Arctic experienced its longest melt season, corresponding with the least amount of sea ice since 1979 and the warmest temperatures since the 1880s. Overall, the length of the melt season is inversely correlated with the lack of sea ice seen in September north of Alaska and Siberia, with a mean correlation of -0.8.

  19. Heterozygote PCR product melting curve prediction.

    Science.gov (United States)

    Dwight, Zachary L; Palais, Robert; Kent, Jana; Wittwer, Carl T

    2014-03-01

    Melting curve