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By Takashi Miyamoto, Hideo Nakae, Hideki Yamaura, Takeshi Yanagihara

"For the production of partially composed metal matrix composites, namely discontinuous MMCs, using a casting· process, the interpenetrated phase composites with SiC particles were fabricated by pressureless iDfiltration using molten Al-Si alloys. This process is based on a wetting phenomenon, therefore, we discussed the technique based on the reactive wetting. The SiC particles coated by diluted water glass were sintered in a mullite Tammann tube and simultaneously infiltrated with molten Al-Si alloys in air at 1173~1573K. As for the improvement of the wettability between the SiC and the liquid aluminum alloy, Fe3O 4 powder was mixed with the water glass due to the thermit reaction between Fe3O4 and molten aluminum alloy. In some experiments, pure aluminum powder was placed on the sintered SiC to increase the interfacial area and the chemical reaction between the sintered Sic. and the melt. By combining these conditions, we succeeded in the complete infiltration without pressure at 1173K.IntroductionAs is well known, the mechanical properties of metal matrix composites (abbreviated MMCs) are superior than that of ordinary metals. However, their use has not been widely accepted because the production cost is very high due to their poor machinability. Therefore, the production of partially composed, namely discontinuous MMCs, by as the Lanxide process [l,2] has been investigated for many years. The Lanxide process, it takes a long time, sometimes up to 10h, in a nitrogen atmosphere for the infiltration. Therefore, the cost will be higher for common use. On the other hand, a high 'pressure process has been adopted for the production of discontinuous MMCs by the Toyota Motor Corp.[3]."

Jan 1, 2000

By J. -C. Tedenac, C. Colinet, X. Tao, P. Jund, R. Viennois

"We report an ab-initio study of the stability and electronic properties of transition metal silicides in order to study their potential for high temperature thermoelectric applications. We focus on the family M5Si3 (M = Ta, W) which is stable up to about 2000 °C. We first investigate the structural stability of the two compounds and then determine the thermopower of the equilibrium structure using the electronic density of states and Mott’s law. We find that W5Si3 has a relatively large thermopower but probably not sufficient enough for thermoelectric applications.IntroductionIn the search of new sustainable energies, thermogeneration of electricity is one of the promising ways, notably because it is able to produce electricity from different kinds of heat wastes and to its portability. However, despite recent progress in the field, the state-of-the art materials have specificities making their mass-production difficult or even impossible: toxicity (thallium, chalcogen or/and pnictogen based alloys), weak abundance (tellurium based alloys) or cost (germanium or rare-earth based alloys). For all these reasons, finding thermoelectric materials without these drawbacks is vital if we wish to use high temperature thermoelectricity for generating electricity in the near future. Due to their abundance, low cost and low toxicity, transition metal silicides are candidate materials of primary interest and the slightest advance in this field would immediately find an application for the thermogeneration of electricity."

Jan 1, 2011

By R. W. Smith

A microorganism will function as a mineral flocculant if it is to some degree hydrophobic and can attach itself in some manner, such as through electrostatic interaction, to the fine mineral particles to be flocculated. The present paper concerns the use of a hydrophobic bacterium, Mycobacterium phlei, as flocculating agent for phosphate slimes. Experimental work on the flocculation of phosphate slimes and of dolomite and clay mineral suspensions was performed. It was found that M. phlei functions as an excellent flocculant for a dolomitic slime but does not function as well for mineral suspensions where large quantities of the solids are finer in size than the approximately 1 µm size of the bacterium.

Jan 1, 1992

By James D. O, DeLa&apos

Multicomponent materials are common in nearly all areas of materials science and technology, yet the use of phase diagrams to represent these complex systems is hampered by the requirement of three or more dimensions for explicit graphical representation. In the present work, the "solid-modeling" capabilities of a computer aided design (CAD) system have been applied to the representation of three-dimensional phase diagrams. Relevant phase diagrams for a hypothetical quaternary eutectic system were constructed and used to demonstrate the capabilities of the technique. These capabilities lead to relative ease of phase diagram construction and improved access to qualitative and quantitative information. Results of this work are contrasted and compared to previous efforts toward computer ,representation of phase diagrams. It is concluded that solid-modeling of three-dimensional phase diagrams can be used to advantage in both education and research.

Jan 1, 1991

By Lucas Nana Wiredu Damoah, Lifeng Zhang

"The use of electromagnetic field to remove suspended particles from metals such as aluminum by pushing to the boundary has been well studied. However, the potential of this method is yet to be exploited for the removal of inclusions from silicon. Considering the increasing amount of Top-cut SoG-Si scraps year upon year, there is the need to harness all the potentials of technologies to recycle this materials to ensure sustainability. This study investigates, and discusses new results on the effect of processing parameters such as composition, coil current, and frequency on the removal of inclusions from silicon under high frequency AC electromagnetic field.IntroductionThe solar cell silicon making industry requires pure and clean silicon in order to maximize the conversion potential of the solar cell material. The conversion efficiency of solar cells is limited by minority carrier recombination at dislocations and those intra-granular defects such as impurities, small clusters of atoms, or precipitates [1]. Recent global developments in the energy sector with a drive for the production of clean, reliable, and affordable energy have stirred a rapid growth in the production of photovoltaic (PV) cells.[2] Thus over the years, silicon based PV cells has seen a lot of growth as it has a PV market share of over 90 % [3] either as single-crystalline silicon, or multi-crystalline Si (MC-Si), or amorphous Si [4]. MC-Si produced by directional solidification of solar grade silicon melt dominates the silicon PV market. During the directional solidification process, SiC and Si3N4 particles within the melt are pushed by the solidification front to the top of the ingot which is the last to solidify. Therefore the top of the ingot is cut generating what is known as top-cut solar silicon scraps. The Si3N4 particles are mainly from the coating material at the inside surface of the silica crucible and from the air absorption during solidification process. The SiC particles mainly stem from the carbon reduction process of the primary production of silicon [5]. For sustainability the silicon in the top-cut silicon scraps must be recovered. Therefore methods for removing non-metallic particles, such as SiC and Si3N4, from the silicon are important in order to recycle the top-cut scraps to a useful feedstock for the silicon solar cells manufacturing."

Jan 1, 2012

By S. Ferlay

"The main purpose of the ZIMA VAL project (Label EUREKA EU1367 and LIFE ENV/F/000278) is to demonstrate industrial scale recovery and recycling of the main components of used dry batteries (zinc, manganese dioxide, mercury, and stainless steel) into high added value products. The originality of the ZIMA VAL process resides in:1- the use of hydrometallurgy2- alkaline treatment implementation (highly selective) for zinc and mercury3- electrochemical recovery of high quality products.4- the recycling of all the battery components (zinc, mercury, manganese dioxide, stainless steel) ·5- low operating and investment costs.The process consists of physical classification, mechanical dismantling, hydrometallurgy and electrochemistry. The purpose of the demonstration plant in FALAISE (Calvados - France) is to define the technical and technological parameters of an industrial unit for the treatment of 2400 tonnes per year of used batteries."

Jan 1, 2000

By T. Yoshida

The Ni-MH (nickel metal hydride) rechargeable battery was developed several years ago. Its higher electrochemical capacity and greater safety compared with the Ni-Cd rechargeable battery have resulted in very rapid Increase in its production. The Ni-MH rechargeable battery consists of Ni. Co and rare earth metals, so that recycling is important to recover these valuable mineral resources. In this study. a basic recycling process for used Ni-MH rechargeable batteries has been developed, in which the Ni. Co and rare earth elements are recovered through a combination of mechanical processing and hydrometallurglcal processing.

Jan 1, 1995

By Leo Brewer, Kazuyoshi Shimakage, Mamoru Mitomo, Toshiyuki Nishimura, Yoichiro Uemura, Shinji Hirai

"In the synthesis process of ß -La2S3 via the sulfurization of La2O3 powder using CS2 gas, La2O2S was formed. This occurred at an initial stage of the reaction for sulfurization temperatures below 973K, and ß -La2S3 was also formed at a shorter period for higher sulfurization temperatures. It was found that the oxygen content in ß -La2S3 powders decreased gradually with an increase in sulfurization temperature. On the other hand, the carbon content in these powders increased gradually with an increase in the sulfurization temperature. Though it has been reported that ß -La2S3 was transformed to Y -La2S3 at 1723K± 50K, the sintered compact of double-phase Y -La2S3 and ß. -La2S3 was formed at a rather higher temperature of 1973K when the synthetic powder of ß -La2S3 containing a high amount of oxygen was used. However, phase transformation of -La2S3 to Y -La2S3 progressed preferentially with a decrease in the oxygen content of synthetic ß -La2S3 powder. The Seebeck coefficient of the sintered double-phase Y -La2S3 and -La2S3 was higher than that of the single-phase Y -La2S3, reported previously.Introduction La2S3 exists in three polymorphic forms that are similar to a series of Ce2S3, Pr2S3 and Nd2S3: a, ß , and Y'. The a -La2S3, which is stable at low temperature, is irreversibly transformed to ß -La2S3 of various compositions in the solid-solution range between La2S3 and La3S4, at 923 ± 50K. The -La2S3 may also be an oxysulfide of La10S14O2. Moreover, the ß .-La2S3 phase is transformed to Y -La2S3 ,which has a Th3P4 structure, at 1573 ± 100K. The melting point of Y -La2S3 is 2398 ± 30K where this temperature is similar to those of common refractory materials such as silica and alumina. Therefore, it can be predicted that y -La2S3 which has a high melting point and a thermodynamic stability due to the strong affinity of La for S, would have &high refractory character and chemical inertness in many molten metals. The y -La2S3, colored vivid faint yellow is stable up to 623K in air, where oxidation starts. y -La2S3 is frequently used as pigments for plastics and paints3. Furthermore, Y -La2S3 which is a semiconductor, is considered to be useful as a thermoelectric conversion materials, because it has a high Seebeck coefficient."

Jan 1, 2000

By David J. Howard, Christine Broadbridge, David C. Paine

"High pressure vapor/solid reactions offer an opportunity for novel synthesis and processing of thin film materials and structures for electronic, optical, and magnetic applications. In this paper we review the use of two high pressure techniques that operate from 25 to 1000 atm (2.5 to 100 MPa) to fabricate thin film oxide structures from Si1-xGex deposited on Si wafers. High pressure synthesis enables temperature-independent control of reaction rates in the oxidation of this multicomponent semiconductor system and hence offers the opportunity to form thennodynamically metastable Si1-xGex<h from the alloy. The thermodynamics of the Si-Ge-0 system are reviewed and a method is described that utilizes selective chemical reduction (via H2 gas) of Si1-xGcx<h to form Ge precipitates in an SiO2 matrix. IntroductionAlloys of Si1-xGex grown epitaxially on Si substrates by chemical vapor deposition (CYD) and molecular beam epitaxy (MBE) have been used to create high performance microelectronic devices1. These devices show improved performance over conventional Si technology because they exploit the Si/Si 1-xGex band-gap discontinuity and take advantage of higher hole mobilities in the Ge containing alloys. While a range of devices based on heteroepitaxial systems have been demonstrated, the Si1_xGex alloys are of particular interest because they are most closely compatable with standard Si device processing. One disadvantage of Si-based materials systems is that they are not typically useful emitters of light. This is important since the use of light (rather than electrons) for transmitting and processing signals into, out of, and within Si-based microelectronics would represent a major technological advance in microelectronics-based communication and computer technologies. Nevertheless, through the use of innovative processing techniques it may be possible to use the Si1_xGex/Si heteroepitaxial system in integrated microelectronic/light-wave technologies."

Jan 1, 1994

By Peter A. Spencer

The metallurgical parameters necessary for the design of a carmercial scale bio-oxidation plant have been determined for the treatment of a refractory arsenopyrite concentrate using a moderately thermophilic bacterial culture. The parameters considered were bio-oxidation rate, culture growth rate, nutrients, solids density, level of bio-oxidation, particle size distribution and oxygen uptake rate. The approach for obtaining the optimum values for these parameters is discussed and values based on results fran batch and continuous testing are given. Estimates of the capital and operating costs for a plant treating the carmercial arsenopyrite concentrate have been calculated fran the test data.

Jan 1, 1990

By Jörn E. Fischer

Cracks were observed at the top of spray formed billets for some alloys. In this paper the effect of process parameters on crack probability is discussed. After the spray run the thermal conditions at the top of the billet change rapidly. A hot spot with melt residue] can occur inside the billet and shrinkage will be suppressed due to the solidified surface of the billet. In this situation hot cracks can be initialized. The temperature history of the billet during and after the spray run is calculated. The temperature difference between core and outside diameter of the billet is taken as indicator for hot crack probability. The effect of different process parameters on the hot crack probability is discussed. The results lead to a better understanding of the process. The calculations are taken as a tool to find process parameters in order to reduce or avoid hot cracks in spray formed billets.

Jan 1, 1999

By Oleg B. Girin, Yuliya O. Proshenko

"Several approaches to electrolytic synthesis of new types of composite coatings with improved properties were devised using the authors' findings on development of texture, substructure and structural state in metal electrocrystallization. Addressed are texturally composite coatings having improved resistance to wear and corrosion; substructurally composite coatings having improved hardness and corrosion resistance; phase-change constitutionally composite coatings having improved corrosion resistance, reflectance, hardness and resistance to wear; structure-change constitutionally composite coatings having improved electric and magnetic properties; restricted-substructure composite coatings having improved resistance to abrasive-impact wear; and modified-substructure composite coatings having improved strength and plasticity.IntroductionIn recent years, some trends in the formation behavior of crystal texture, crystal substructure and structural state of electroplates were revealed and effects of texture, substructure and structural type on electroplate properties were discovered (1-3). Our interest was in using these findings and effects to develop some ways of synthesizing new types of composite electrolyte coatings having enhanced properties."

Jan 1, 1998

By Marcela C. Santini, Luiz A. Teixeira

"Surface conditioning (also referred as etching) of plastics prior to metallization is generally conducted with sulfuric I chromic acid solutions. Although these baths perform well technically, the presence of Cr (VI) imposes serious operating problems of an environmental nature. The present work reports ·the results of a study of surface conditioning o(ABS using solutions based. on sulfuric acid, with hydrogen peroxide and/or nitric acid, replacing chromic acid, as oxidants. Process performance was evaluated by SEM and by the uniformity and adherence of electroless nickel coatings applied on selected conditioned samples. The results showed that the evaluated types of solutions could be optimized to perform as well as the chromic-based baths, with a much superior environmental quality.IntroductionMetallization of plastics is normally undertaken for either decorative or functional purposes. Through metallization, the specific properties of plastics such as light weight, design flexibility, and low-cost of manufacturing are enhanced by the addition of properties usually associated with metals. These include reflectiveness, abrasion resistance, electrical conductivity, and a variety of decorative effects (1).The available processes that can be used for metallization of plastics are vacuum metallization or vapoµr deposition; indirect metallization and plating (1). Plating can be sub-divided into electroless plating and electroplating. In electroless plating, metal ions in aqueous solution are deposited on the .activated plastic surface by oxi-reduction reactions without the aid of an external electric potential, forming a thin metallic layer. This electroless deposited film has two functions: (a) it provides an electrically conductive substrate that allows further coating by electroplating; and (b) provides a secure bond between the plastic substrate and the electroplated layer (1,2). In case the electroless metallic part requires an additional layer for finishing purposes, or just an increase in thickness, the part can be additionally electroplated with a· variety of metals - in most cases those are copper, nickel or chromium (3)."

Jan 1, 2000

By Philip Nash, Jie Zhou, Joshua Blackketter

"Large ingots tend to have internal defects such as shrinkage cavities and porosities, which have to be closed during the cogging stage to ensure sound internal quality of forged parts. In this work, finite element methods were used to simulate open die forging passes, with varying parameters that affect the void closure behavior profoundly. Numerical models ware constructed in ABAQUS, DEFORM and FORGE using data taken from footage of the forging process and material mechanical data obtained from the Gleeble compression tests. Forging variables such as pass rotation, reduction per pass, and feed ratio were studied with intense attention paid on the special properties of H13 steel, so that this study can be applied to solve real world problem.IntroductionCenterline defect closure is a frequently studied but still challenging topic in open die forging industry. In practice, open die forging is employed as an effective hot forming process to make desired shape of metal products as well as to ensure center consolidation of internal defects which result from the casting process. Nowadays, remarkable large forgings have been more and more required to meet industries demand. However, the increase in ingot size has tended to result in considerable macrosegregations and shrinkage cavities or voids, which need to be worked thoroughly during the forging process; but the size of the products and limitations of manufacturing capacity, such as the press load, make it difficult to achieve adequate local deformation to close those defects. Therefore, choosing optimal forging parameters under given work condition to ensure good internal quality of forged products is critically important."

Jan 1, 2012

By Daoxin Wu

Originated from(C4H9O)4Ti, nano--rutile TiO2 was synthesized by low temperature hydrolysis process in this paper. After being prepared by decomposing ammonium tungstate and covering on the surface of TiO2, TiO2/WO3 were characterized by means of X-ray diffraction(XRD), UV--vis difuse reflectance(DRS), fluorescence spectrum (FS). Results showed that with the increase of the supported concentration of WO3, the reflectance of DRS and the fluorescence spectrum intensity of TiO2/WO3 decreased accordingly, which indicated the powder?s increase in light absorbance and the decrease in luminescence respectively; with the increase of calcined temperature, the reflectance of DRS increased.

Jan 1, 2009

By Geir Wedde, Anders Sorhuus

"Vast quantities of energy are released as heat to the environment from industrial operations. Many countries target waste heat recovery to mitigate CO2 emission. Exhaust gases from industries such as primary aluminium smelting, carry a substantial portion of the waste heat generated. For a cost efficient capture of more valuable heat (higher exergy), heat exchangers should operate on the exhaust gases upstream of the gas treatment plants. Heat exchange surface would be exposed to dust laden gases with risk of fouling. Heat exchangers of innovated design and operation have overcome the potential of excessive fouling rates. Heat exchangers of the ""shell and tube"" design have been demonstrated for exhaust gases from ferroalloy as well as primary aluminium smelters. In addition to the heat recovery, gas cooling results in smaller gas treatment plants with lower costs and reduced emission. The aluminium experience is exampled in the paper.IntroductionIndustrial usage of energy continues to grow as a result of increasing volumes of production, a trend that is likely to continue in the coming decades as living standards keep rising globally. World energy consumption (Figure la) is to grow 49 % by 2035 (ref. 2010) as reported by EIA [1]. The industrial sector consumes somewhat more than 50% of the total world energy consumption predominantly the energy increased demand comes from non-OECD countries in Asia. The industrial consumption by production of metals iron and steel accounts for 14 % and for non-ferrous metals 3 % mostly for aluminium production (Figure lb). Aluminium production will be discussed in this paper as an example of an industry with large quantities of waste heat to recover"

Jan 1, 2012

By Animesh Jha

Univariant diagrams are constructed for the reduction of nickel and cobalt oxide and sulphide minerals. The results from the carbothermic and hydrogen reduction of sulphide minerals are compared. The importance role of lime and calcium sulphate in controlling the emission of sulphurous- gases during reduction reaction is also explained. The mechanism of carbothermic reduction of nickel sulphide is explained by examining the sulphur exchange and reduction reactions. The phase equilibrium relationships that determine the formation of multicomponent liquid are characterised. Also the governing equilibria for inert atmosphere calcination- roasting of nickel and cobalt sulphide minerals are also described for the metallization of nickel and cobalt.

Jan 1, 1993

By Kazuyo Yokoyama

New environmental assessment model based on the Waste Input-Output analysis has been developed and applied for the "Landfill mining activity". "Landfill mining" implies the digging up of the landfilled wastes, the recovery of valuable material and energy resources and, thus, the reuse of the saved space as a new landfill site. In this study, the landfilled wastes are assumed to be treated by the gasification/melting processes. Two kinds of reactors, the fluidized bed type (FB) and the shaft furnace type (SF), have been considered in this work as the typical gasification/melting processes adopted in Japan. In FB, the dug-up wastes are heated in the sand fluidized bed zone under reducing atmosphere, Fe and Al are recovered in the metallic form, and then, the gasification/melting of residues is made in the second zone. In SF, the waste is charged in the high temperature coke bed, and the gas is recovered together with molten metal and slag. Both processes generate electric power by the recovered heat and fly ash as waste to landfill. It has been found in this study that the both processes can reduce the total volume of waste and save the available landfill space. SF seems to have higher potential for decreasing volume of wastes because of less emission than FB while FB has great benefit to recover metallic Fe and Al individually. The results of scenario analysis have also indicated that the landfill mining activity is effective for sustainable management of landfill sites.

Jan 1, 2006

By Jan Steinhoff

The design options of a gravity separator are still limited and rely on the study of settling behavior. A methodology will be presented where an experimentally given inlet droplet size distribution (DSD) is the basis for the calculation of the dispersion layer in a gravity separator. A pilot-scale continuous gravity separator is presented and CFD (computational fluid dynamic) results are validated. A transmitted light measurement technique for the determination of the DSD is presented up to a holdup of 15% dispersed phase. The resulting DSD was in the range of 20–2000 μm depending on flow rate and phase ratio. Furthermore, correlations of the real DSD with the settling behavior of the dispersion in a settling cell are discussed. The new approach to the description of gravity separators will be presented and the applied CFD methods showed good results with the system water/paraffin.

By Matti Leiponen

During the last few years Outokumpu Oy has put forth efforts to develop the material handling in the Pori tankhouse. The final objective is full automation including cell loading. The fully automated material handling provides high quality anodes and cathodes as well as equipment and handling systems capable of very accurate cell loading. The new machines and equipment for accurate cell loading and the methods to produce high quality anodes and starting sheets are described in this paper.

Jan 1, 1987