- Email: [email protected]
Chemical and electrical insulation of fine iron and cobalt particles
MECHANICAL PROPERTIES OF MICROGRAINED TUNGSTEN CARBIDECOBALT ALLOY H. Ike et al. (Fuji Die Co., Tokyo, Japan.) J.Japan
Sot.
Powder
and Powder
Metal-
Vol 42, No 4, 1995, 517-521. (In Japanese.) It is reported that WC-(6 to 13)wt%Co had been vacuum sintered and the mechanical properties determined. The powders were micrograined. The sintered material had a Vickers hardness of 1800 to 1900. Fracture properties were investigated and cracks were found to initiate at hardness indentations. lurgy,
IMPROVEMENTS IN UNIFORMITY OF THICKNESS OF CVD ALUMINA COATINGS ON CEMENTED CARBIDES H. Suzuki et al. (Chiba Inst of Technology, Narashino, Japan.) J.Japan Sot. Powde-r and Powder Metallurgy, Vol42, No 4, 1995, 528531. (In Japanese.) Studies of chemical vapour deposition of AlzOe on cemented carbide substrates are described the object being to make coatings of greater uniformity in thickness. Gas composition, flow rate, pressure aand effects of deposition rate, structure and quality of the deposit were investigated. USE OF A DIRECT CURRENT PLASMA FLUIDIZED BED REACTOR FOR DL4MOND SYNTHESIS L.X Liu et al. (University of Queensland, St.Lucia, Australia.) Powder Technology, Vol 88, No 1, 1996, 65-70. A DC conical plasma fluidized bed was used for synthesis of diamond by CVD. The bed was found to quench the gas. Apparatus is described. Temperatures and temperature distribution are discussed. Deposition of diamond occured mainly in the tail of the plasma flame. Limitations of the technique are reviewed. STRUCTURALFEATURESOF SYNTHESIS OF SUPERHARD PHASES UNDER HIGH PRESSURES A.V. Kurdyumov. Poroshkovaya Metallurgiya, No 7/8, 1995, 83-91. (In Russian.) Structural transformations in B nitrides and C, at high pressures, are reviewed in terms of diffusion and martensitic mechanisms resulting in formation of hard materials. Crystal perfection of initial structures is considered as this has influence on mechanisms during impact compaction.
lntermetal/ic materials PROCESSES INFLUENCING SHOCK CHEMISTRY OF TITANIUM BASED SYSTEMS N.N. Thadhani et al. (Georgia Inst. of Technology, Atlanta, USA) Metall. and 44
MPR April 1997
Ft-ans A, Vol 27A, No 7, 1996, 1761-1771. An investigation of Ti-Si, Ti-Al and Ti-B powder systems, in unreacted and reacted states, is described. Microstructures are characterized as functions of shock compression and recovery. It is reported that mechanisms are dominated by differences in shock response. Ease of initiation of reaction decreases in the order Ti-Si, Ti-B, Ti-Al in respect of thermodynamics of the systems. Differences in mechanical properties of the reactants affects response to shock compaction. Mater.
NICKEL ALUMINIDE PARTICLES AS WEAR RESISTANT REINFORCEMENT IN PM ALUMINIUM COMPOSITES
Metal injection moulding INVESTIGATIONS OF BINDER REMOVAL IN METAL INJECTION MOULDING D. Bialo, T. Kulesza. (Polytechnic of Warsaw, Warsaw, Poland.) Metal. Proszkm, Vol 29, No 1, 1996, 3-ll.(In Polish.) Debinding of 316L stainless steel, carbonyl Fe and cemented carbides, with paraffin wax of polyethylene oxide binders, was investigated using solvent and thermal methods. The results are presented graphically. Fractured specimens were examines by scanning electron microscopy.
EURO PM’96: The abstracts M. Lieblich et al. (National Centre for Metallurgical Investigations, Madrid, Spain.) Metall. and Mat&. Trans A, Vol 274 No 10, 1996, 3259-3266. Wear properties, against steel, of Al alloy-5vol%NisAl composites were investigated in air and compared with unreinforced material. It is reported that Fe oxide particles became embedded in the Al matrix. The results are used to show that load bearing is by the N&Al reinforcements which are well bonded to the matrix. Embedding of wear debris was limited and there was less wear of the steel counterfaces. KINETICS OF COMBUSTION SYNTHESIS OF MAGNESIUM-NICKEL INTERMETALLIC J Yagi et al. (Tohoku University, Sendai, Japan.) J. Japan Inst. of Metals, Vol 60, No 7, 1996, 640-646. (In Japanese.) Energetics of combustion synthesis of MgzNi are discussed and investigations of structure are described. The synthesis is shown to proceed uniformly and no intermediate phase was detected. The reaction rate was increased by presence of a liquid eutectic and the rate equation is shown to be second order. SYNTHESIS OF TITANIUM ALUMINIDE BY POWDER METALLURGY METHOD KJ. Park, S.K.Hwang. (Inha University, Inchon, Korea.) J. Korean Inst. of Metals, Vol 34, No 3, 1996, 296-305. (In Korean.) An investigation of synthesis of Ti&s, with addition of Cu, by reactive sintering alone or in combination with pseudo-HIP is described. Cu is shown to enhance densification. This is attributed to the effect of Cu on mutual solubility of Ti and Si. Reduced particle size increased sintered density. Without pseudo-HIP densities of 93% were attained which was increased to 99% by pseudo-HIP.
follow
are
of
papers
which
which were
presented at the Conference on Hard Metals Production held in Stockholm, Sweden, in May 1996.
Processing HARDMETAL PARTS BY INJECTION MOULDING USING A POLYACETYL BASED BINDER SYSTEM W. Hesse, P. Tnibenbach. (BASF AG, Germany.) Use of injection moulding for hardmetal parts was discussed with note taken of process problems, particularly, segregation due to high density of WC and undesirable chemical reactions during debinding. Catalytic debinding of polyacetyl binders using oxalic acid as the catalyst was considered. Properties of hardmetal feedstocks and process conditions were discussed and examples of IM parts were presented. CHEMICAL AND ELECTRICAL INSULATION OF FINE IRON AND COBALT PARTICLES A Garreau, P. l&are. (CEA, France.) Phosphate coating of fine Fe and Co powders was discussed with regard to chemical and electrical effects. It was reported that phosphate coating increases oxidation resistance up to 400°C but thermal treatment is required to stabilize the coating. The possibility of mixing the metal powder with a binder without any chemical interaction was noted and choice of stable binder was reviewed. HMZ SPECIAL SERVICE RECYCLING C. Stambolidis. (HMZ as, Czech Republic.) It was reported that work on recycling W scrap into WC and W powders is in progress. Process steps were summarized as roasting, wet processing, reduction and carburizing.
Sot.
Powder
and Powder
Metal-
Vol 42, No 4, 1995, 517-521. (In Japanese.) It is reported that WC-(6 to 13)wt%Co had been vacuum sintered and the mechanical properties determined. The powders were micrograined. The sintered material had a Vickers hardness of 1800 to 1900. Fracture properties were investigated and cracks were found to initiate at hardness indentations. lurgy,
IMPROVEMENTS IN UNIFORMITY OF THICKNESS OF CVD ALUMINA COATINGS ON CEMENTED CARBIDES H. Suzuki et al. (Chiba Inst of Technology, Narashino, Japan.) J.Japan Sot. Powde-r and Powder Metallurgy, Vol42, No 4, 1995, 528531. (In Japanese.) Studies of chemical vapour deposition of AlzOe on cemented carbide substrates are described the object being to make coatings of greater uniformity in thickness. Gas composition, flow rate, pressure aand effects of deposition rate, structure and quality of the deposit were investigated. USE OF A DIRECT CURRENT PLASMA FLUIDIZED BED REACTOR FOR DL4MOND SYNTHESIS L.X Liu et al. (University of Queensland, St.Lucia, Australia.) Powder Technology, Vol 88, No 1, 1996, 65-70. A DC conical plasma fluidized bed was used for synthesis of diamond by CVD. The bed was found to quench the gas. Apparatus is described. Temperatures and temperature distribution are discussed. Deposition of diamond occured mainly in the tail of the plasma flame. Limitations of the technique are reviewed. STRUCTURALFEATURESOF SYNTHESIS OF SUPERHARD PHASES UNDER HIGH PRESSURES A.V. Kurdyumov. Poroshkovaya Metallurgiya, No 7/8, 1995, 83-91. (In Russian.) Structural transformations in B nitrides and C, at high pressures, are reviewed in terms of diffusion and martensitic mechanisms resulting in formation of hard materials. Crystal perfection of initial structures is considered as this has influence on mechanisms during impact compaction.
lntermetal/ic materials PROCESSES INFLUENCING SHOCK CHEMISTRY OF TITANIUM BASED SYSTEMS N.N. Thadhani et al. (Georgia Inst. of Technology, Atlanta, USA) Metall. and 44
MPR April 1997
Ft-ans A, Vol 27A, No 7, 1996, 1761-1771. An investigation of Ti-Si, Ti-Al and Ti-B powder systems, in unreacted and reacted states, is described. Microstructures are characterized as functions of shock compression and recovery. It is reported that mechanisms are dominated by differences in shock response. Ease of initiation of reaction decreases in the order Ti-Si, Ti-B, Ti-Al in respect of thermodynamics of the systems. Differences in mechanical properties of the reactants affects response to shock compaction. Mater.
NICKEL ALUMINIDE PARTICLES AS WEAR RESISTANT REINFORCEMENT IN PM ALUMINIUM COMPOSITES
Metal injection moulding INVESTIGATIONS OF BINDER REMOVAL IN METAL INJECTION MOULDING D. Bialo, T. Kulesza. (Polytechnic of Warsaw, Warsaw, Poland.) Metal. Proszkm, Vol 29, No 1, 1996, 3-ll.(In Polish.) Debinding of 316L stainless steel, carbonyl Fe and cemented carbides, with paraffin wax of polyethylene oxide binders, was investigated using solvent and thermal methods. The results are presented graphically. Fractured specimens were examines by scanning electron microscopy.
EURO PM’96: The abstracts M. Lieblich et al. (National Centre for Metallurgical Investigations, Madrid, Spain.) Metall. and Mat&. Trans A, Vol 274 No 10, 1996, 3259-3266. Wear properties, against steel, of Al alloy-5vol%NisAl composites were investigated in air and compared with unreinforced material. It is reported that Fe oxide particles became embedded in the Al matrix. The results are used to show that load bearing is by the N&Al reinforcements which are well bonded to the matrix. Embedding of wear debris was limited and there was less wear of the steel counterfaces. KINETICS OF COMBUSTION SYNTHESIS OF MAGNESIUM-NICKEL INTERMETALLIC J Yagi et al. (Tohoku University, Sendai, Japan.) J. Japan Inst. of Metals, Vol 60, No 7, 1996, 640-646. (In Japanese.) Energetics of combustion synthesis of MgzNi are discussed and investigations of structure are described. The synthesis is shown to proceed uniformly and no intermediate phase was detected. The reaction rate was increased by presence of a liquid eutectic and the rate equation is shown to be second order. SYNTHESIS OF TITANIUM ALUMINIDE BY POWDER METALLURGY METHOD KJ. Park, S.K.Hwang. (Inha University, Inchon, Korea.) J. Korean Inst. of Metals, Vol 34, No 3, 1996, 296-305. (In Korean.) An investigation of synthesis of Ti&s, with addition of Cu, by reactive sintering alone or in combination with pseudo-HIP is described. Cu is shown to enhance densification. This is attributed to the effect of Cu on mutual solubility of Ti and Si. Reduced particle size increased sintered density. Without pseudo-HIP densities of 93% were attained which was increased to 99% by pseudo-HIP.
follow
are
of
papers
which
which were
presented at the Conference on Hard Metals Production held in Stockholm, Sweden, in May 1996.
Processing HARDMETAL PARTS BY INJECTION MOULDING USING A POLYACETYL BASED BINDER SYSTEM W. Hesse, P. Tnibenbach. (BASF AG, Germany.) Use of injection moulding for hardmetal parts was discussed with note taken of process problems, particularly, segregation due to high density of WC and undesirable chemical reactions during debinding. Catalytic debinding of polyacetyl binders using oxalic acid as the catalyst was considered. Properties of hardmetal feedstocks and process conditions were discussed and examples of IM parts were presented. CHEMICAL AND ELECTRICAL INSULATION OF FINE IRON AND COBALT PARTICLES A Garreau, P. l&are. (CEA, France.) Phosphate coating of fine Fe and Co powders was discussed with regard to chemical and electrical effects. It was reported that phosphate coating increases oxidation resistance up to 400°C but thermal treatment is required to stabilize the coating. The possibility of mixing the metal powder with a binder without any chemical interaction was noted and choice of stable binder was reviewed. HMZ SPECIAL SERVICE RECYCLING C. Stambolidis. (HMZ as, Czech Republic.) It was reported that work on recycling W scrap into WC and W powders is in progress. Process steps were summarized as roasting, wet processing, reduction and carburizing.