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Effect of material and process parameters on sinter hardening alloys
Powder production PREPARATION AND CHAR4CTERIZATION OF ZIRCONL4 BASED CERAMIC POWDERS N. Khan, K.A. Qureshi (Pakistan Inst. of Nuclear Science and Technology, Pakistan). Electrical applications of ceramics, notably ZrOa, were discussed. A study of production methods was described. It was reported that a sol-gel technique yielded loosely agglomerated highly reactive ZrCz powders. Sol-gel sub-micron ZrCz powders were characterized and compared with other ZrOz powders and were reported to be superior. VACUUM DEGASSING OF ATOMIZED ALUMINIUM-IRON ALLOYS J.L.H. Estrada, J. Duszczyk (Technological University, Delft, The Netherlands). Oxidation and degassing of Al alloys were investigated. Oxidation during atomization was discussed with reference to the role of water the oxide layer being up to 10 nm thick. Degassing was carried out by heating canned powders in vacuum for a range of alloys. Degassing was discussed quantitatively in terms of Wagner’s theory of oxidation. HOT DEGASSING OF HIGH ALLOY METAL POWDERS L. Nyborg, S. Magalhuaes (Chalmers University of Technology, Sweden). Degassing of Fe and Ni based superalloy powders was discussed with regard to the effect on final compact properties. Studies to determine whether differences in degassability affect precipitation at prior particle boundaries were undertaken. Relationships between degassed powder volume and particle size were established. Layer degassing was described.
Heat treatment EFFECT OF MATERIAL AND PROCESS PARAMETERS ON SINTER HARDENING ALLOYS A. de Rege et al. (Domfer Metal Powders, Montreal, Canada). Sinter hardening of steel was discussed with regard to properties and the elimination of a process stage. A study of the effects of composition and density on hardenability, structure and properties of sinter hardening parts was described. HARDENABILITY CHARACTERISTICS OF PM ALLOY STEELS C.C. Skena, T. Prucher (Concurrent Technologies Corp, USA). Current knowledge of heat treatment response of PM steels was discussed. Jominy
38 MPR December 1996
tests were performed on a range of PM alloy steels, some made Tom prealloyed and others from diffusion bonded powders, at a range of density, It was reported that hardenability increases with density and %C, and that diffusion bonded powders required higher alloy contents to attain the same hardenability. MAXIMIZATION OF HARDNESS OF A STEAM TREATED PART S. Ashok et al. (Sandram Fasteners Ltd, India). It was noted that a minimum Rockwell hardness of 80 B was required for oil pump inner rotors and that a range of 76 to 84 was being attained, with high rejection rates. It is reported that by use of new process technology a hardness range of 88 to 94 was attained.
Modelling INTEGRATION OF COMPUTER APPLICATIONS IN PM TOOL DESIGN M. him, DC. Zenger (Worcester Polytechnic Inst., USA). It was noted that advances in computers had led to new applications in development and design of PM tooling giving optimized performance. An analysis of PM tooling to integrate design with computer use was reported. Examples and an outline of factors were given. PERMEABLE ELEMENT METHOD FOR MODELLING OF POWDER COMPACTION IN RIGID DIES E. Olevsky et al. (University of California, San Diego, USA The permeable element method, as a development of finite element approximation, in study of densification of porous bodies was described. A Eulerian frame of reference was used. Element shape and network movement were chosen for convenience in calculation. PEM was applied to pressing a hollow cylinder. Calculated and measured data were compared.
Sintering atmospheres SINTERING ATMOSPHERES FOR IRONCARBON-COPPER PARTS J.G. Marsden et al. (Air Products and Chemicals, Inc, USA). The importance of correct atmosphere selection for sintering C-Cu steels was discussed with regard to use of N/H/ natural gas mixtures and quality, properties and cost of parts. Effects of atmosphere composition and sintering temperatures on properties and structure of Fe-C-Cu alloys were investigated and described.
EFFECTS OF HYDROGEN ON SINTERED PROPERTIES OF STEEL PARTS V. Demling et al. (Monroe Australia Pty Ltd, Australia). Fe-C and Fe-C-Cu compacts were delubricated and sintered under a range of conditions. Effects of H content of the sintering atmosphere were determined. Optimum H contents for given alloys and furnace types were recommended. THERMODYNAMICS OF PROTECTIVE ATMPOSPHERE CONTROL P. Beiss (Inst. for Materials Science, Germany). It was noted that modern sintering furnaces allow control of C potential to prevent decarburization but allow reduction of oxides of alloy elements. The thermodynamic background and data were presented.
Injection moulding DEVELOPMENT OF WAX AND POLYETHYLENE GLYCOL BASE BINDER SYSTEMS R.M. German et al. (Pennsylvania State University, Pennsylvania, USA). Wax and polyethylene glycol (PEG) based binders for metal and ceramic injection moulding were discussed with regard to properties of binder and feedstock, solids loading, properties of and environmental compacts considerations. A study of of these binders with carbonyl Fe and AlaOs was described. Particle morphology and surface chemistry were determined before mixing with binder. Torque rheometry was used to establish suitable binder systems, composition and mixing parameters. The study was reported to provide a basis for binder system selection. NOVEL FEEDSTOCKS FOR INJECTION MOIJLDING L Bogan et al. (Rohm and Haas Speciality Materials, USA). It was reported that novel powder injection moulding feedstocks were developed which allowed rapid debinding without special treatment. The feedstock is baaed on a new binder. The feedstocks were compared with those containing paraffin wax, polyethylene glycol and polyacetyl. TYPICAL DEFECTS IN INJECTION MOUDED PARTS - AND HOW THEY CAN BE AVOIDED J.S. Ebenhoech, D.C. Krueger (BASF Corp, USA). Powder injection moulding was discussed and the frequent low yield of parts was noted. Defects are shown to arise at any stage in the production process.
Heat treatment EFFECT OF MATERIAL AND PROCESS PARAMETERS ON SINTER HARDENING ALLOYS A. de Rege et al. (Domfer Metal Powders, Montreal, Canada). Sinter hardening of steel was discussed with regard to properties and the elimination of a process stage. A study of the effects of composition and density on hardenability, structure and properties of sinter hardening parts was described. HARDENABILITY CHARACTERISTICS OF PM ALLOY STEELS C.C. Skena, T. Prucher (Concurrent Technologies Corp, USA). Current knowledge of heat treatment response of PM steels was discussed. Jominy
38 MPR December 1996
tests were performed on a range of PM alloy steels, some made Tom prealloyed and others from diffusion bonded powders, at a range of density, It was reported that hardenability increases with density and %C, and that diffusion bonded powders required higher alloy contents to attain the same hardenability. MAXIMIZATION OF HARDNESS OF A STEAM TREATED PART S. Ashok et al. (Sandram Fasteners Ltd, India). It was noted that a minimum Rockwell hardness of 80 B was required for oil pump inner rotors and that a range of 76 to 84 was being attained, with high rejection rates. It is reported that by use of new process technology a hardness range of 88 to 94 was attained.
Modelling INTEGRATION OF COMPUTER APPLICATIONS IN PM TOOL DESIGN M. him, DC. Zenger (Worcester Polytechnic Inst., USA). It was noted that advances in computers had led to new applications in development and design of PM tooling giving optimized performance. An analysis of PM tooling to integrate design with computer use was reported. Examples and an outline of factors were given. PERMEABLE ELEMENT METHOD FOR MODELLING OF POWDER COMPACTION IN RIGID DIES E. Olevsky et al. (University of California, San Diego, USA The permeable element method, as a development of finite element approximation, in study of densification of porous bodies was described. A Eulerian frame of reference was used. Element shape and network movement were chosen for convenience in calculation. PEM was applied to pressing a hollow cylinder. Calculated and measured data were compared.
Sintering atmospheres SINTERING ATMOSPHERES FOR IRONCARBON-COPPER PARTS J.G. Marsden et al. (Air Products and Chemicals, Inc, USA). The importance of correct atmosphere selection for sintering C-Cu steels was discussed with regard to use of N/H/ natural gas mixtures and quality, properties and cost of parts. Effects of atmosphere composition and sintering temperatures on properties and structure of Fe-C-Cu alloys were investigated and described.
EFFECTS OF HYDROGEN ON SINTERED PROPERTIES OF STEEL PARTS V. Demling et al. (Monroe Australia Pty Ltd, Australia). Fe-C and Fe-C-Cu compacts were delubricated and sintered under a range of conditions. Effects of H content of the sintering atmosphere were determined. Optimum H contents for given alloys and furnace types were recommended. THERMODYNAMICS OF PROTECTIVE ATMPOSPHERE CONTROL P. Beiss (Inst. for Materials Science, Germany). It was noted that modern sintering furnaces allow control of C potential to prevent decarburization but allow reduction of oxides of alloy elements. The thermodynamic background and data were presented.
Injection moulding DEVELOPMENT OF WAX AND POLYETHYLENE GLYCOL BASE BINDER SYSTEMS R.M. German et al. (Pennsylvania State University, Pennsylvania, USA). Wax and polyethylene glycol (PEG) based binders for metal and ceramic injection moulding were discussed with regard to properties of binder and feedstock, solids loading, properties of and environmental compacts considerations. A study of of these binders with carbonyl Fe and AlaOs was described. Particle morphology and surface chemistry were determined before mixing with binder. Torque rheometry was used to establish suitable binder systems, composition and mixing parameters. The study was reported to provide a basis for binder system selection. NOVEL FEEDSTOCKS FOR INJECTION MOIJLDING L Bogan et al. (Rohm and Haas Speciality Materials, USA). It was reported that novel powder injection moulding feedstocks were developed which allowed rapid debinding without special treatment. The feedstock is baaed on a new binder. The feedstocks were compared with those containing paraffin wax, polyethylene glycol and polyacetyl. TYPICAL DEFECTS IN INJECTION MOUDED PARTS - AND HOW THEY CAN BE AVOIDED J.S. Ebenhoech, D.C. Krueger (BASF Corp, USA). Powder injection moulding was discussed and the frequent low yield of parts was noted. Defects are shown to arise at any stage in the production process.