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Thermal removal of stearic acid from injection moulded specimens of stainless steel
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HOT PRESSED WEAR RESISTANT I R O N ~ H R O M I U M ALLOY WITH HARD PHASE MECHANICALLY ALLOYED SURFACE
B. Martner and E. Friedrich, (Dresden University of Technology, Germany). Production of a novel wear resistant material by impacting hard BC powder into the surface of relatively tough Fe(Cr) powder by ball milling was described. The composite powder was consolidated by hot pressing for a short time to minimize dissolution of BC into the matrix. Stresses and temperature generated during abrasion cause dissolution of BC in the surface layers and ensures the formation of a hard, wear resistant, surface. Process technology, structural changes and wear properties were reported.
LITERATURE
REVIEVt
Steel specimens, prepared from atomized powder were brazed or diffusion bonded in green and sintered conditions. Four brazing alloys were used and the strength and hardness of the joints, as a function of density, were compared with those of the parent metals.
Powder injection moulding COMPARISON OF INJECTION MOULDING OF POWDER/BINDER MIXTURES AND PLASTIC MATERIAL
B.O. Rhee and C.I. Chung, (Rensselaer Polytechnic Inst, Troy, N e w York, USA). It was noted that metal and ceramic materials are often injection moulded on machines designed for use with polymers. Design of machines was discussed with FORMING METHOD FOR A MULTILAYER regard to differences between polymers and PM COMPOSITE MATERIAL PIM feedstocks. Freezing times for both were c o m p a r e d experimentally and L.Y. Li and H.H. Wang, (Qingdao Research analytically. Possible solutions for the problem of premature freezing were Inst of PM, China). Uniaxial compaction for production of discussed. multilayer c o m p o s i t e s was described. STRUCTURE APPROACH TO Applications included oil impregnated INJECTION MOULDING OF POWDERb e a r i n g s and m e c h a n i c a l p a r t s with BINDER MIXTURES medium to high strength.
Joining technology DEVELOPMENT OF TECHNOLOGY FOR LASER WELDING OF SINTERED STEEL PARTS
Y. Mural et al, (Kobe Steel Ltd, Kobe, Japan). The use of C O 2 lasers for joining high C steel was described. Without a filler the joints were reported to contain defects, cracks and blowholes. The filler was selected to control martensite formation, promote deoxidation and fix S and N in the steel. Use of laser welding for 0.8% C steel and 0.6% C low alloy steel was reported. COPPER BRAZING OF PM COMPONENTS TO WROUGHT PARTS
B. Marzella et al, (Clarion Sintered Metals, Ridgeway, USA). The brazing of sintered and wrought steel sub-components was described. The P M steel was Cu infiltrated and it was reported the satisfactory joints were produced. Cost savings were claimed because of the reduction in finishing operations. The powder mixture, control of %C, sintered and green densities and assembly were discussed. JOINING OF IRON RASED PM COMPONENTS BY BRAZING AND DIFFUSION BONDING
B. Clausen and ICA. Thorsen, (Technical University of Denmark, Copenhagen, Denmark).
50 MPR November 1992
R.T. Fox et al, (Rensselaer Polytechnic Inst, Troy, New York, USA). An outline of the objectives of PIM, the production components to c l o s e d i m e n s i o n a l t o l e r a n c e s with u n i f o r m microstructures and improved properties in a cost effective way was presented. The prerequisites for successful PIM, knowledge of the feedstock rheology and the effects of process parameters on the integrity of the part were discussed. Flow behaviour o f a r a n g e of f e e d s t o c k s was d e t e r m i n e d experimentally. Finite element methods were used to analyze the physical and mechanical properties. When applied to actual moulding trails causes of defects can be identified and avoided by proper control of m o u l d i n g p a r a m e t e r s and optimum moulding conditions established. NOVEL BINDER FOR RAPID DEBINDING OF POWDER INJECTION MOULDED SAMPLES
H.H. Andermann and A. van der Biest, (Leuven University, Belgium). The rapid removal of a novel binder from PIM compacts, without wicking or solvent was described. A cylindrical sample 13 mm x 10 ram, made from carbonyl Fe powder w a s d e b o u n d in 5 h o u r s w i t h o u t deformation, results for 316L stainless steel and alumina were also given. NOVEL PROCESS CONTROL METHODS FOR BINDERS BASED ON THERMOSET CONDENSATION RESINS G.M. Brasel and J.E. Duke, (Megamet Industries lnc, St. I~uis, USA).
In-moulding debinding, by the Megamet process, was described with regard to the process controls required. Green compacts were produced without the use of an i n j e c t i o n m o u l d i n g m a c h i n e . The importance of the relationship between the properties of the powder, binder and additives was emphasized. Control of green density was exercised through pressurization control and mould venting in a novel way. EFFECTS OF POWDER CHARACTERISTICS AND DEBINDING CONDITIONS ON DEFORMATION BEHAVIOUR OF INJECTION MOULDED COMPACTS DURING THERMAL DEBINDING
R. Miura and S. Takamori, (Japan Steel Works Ltd, Japan). The causes of distortion during debinding, the weight of the compact and viscous creep, were discussed. A n investigation of deformation in three-point bending of a beam was described. Effects of powder morphology and size distribution, bending moment, solid/binder ratio, heating rate, temperature and atmosphere were outlined. ATMOSPHERE PROCESS FOR THE CONTROL OF CARBON AND OXYGEN CONTENTS DURING DEBINDING OF INJECTION MOULDED STEEL
M.A. Phillips et al, (Liquid Air Corp, Countryside, Illinois, USA). The effects of binder decomposition during debinding in increasing the C content of alloys was discussed. This is partly offset by decarburization by reaction with O. The effect of gas composition of %C in Fe-2%Ni steels was evaluated. Precise C content could be attained by adjusting gas composition and debinding parameters. PROCESS PARAMETERS FOR A FAST CATALYTIC DEBINDING SYSTEM
D. Weinand and M. Blomacher, (BASF AG, Ludwigshafen, Germany). Catalytic debinding of injection moulded parts was discussed and was said to offer advantages over conventional debinding p r o c e s s e s . Th e p r o c e s s p a r a m e t e r s r e l e v a n t to e c o n o m i c a n a l y s i s w e r e investigated. Feedstock theology, thermal history, cycle time and green strength were considered. Continuous and discontinuous debinding were discussed. EVOLUTION OF GASES AND SINTERING BEHAVIOUR IN CARBONYL IRON POWDER FOR INJECTION MOULDING
S. Igarashi et al, Tokyo, Japan). It was noted contains volatile and O and that
(Sumitomo Metal Mining, that carbonyl Fe powder impurities including C, N little research had been
HOT PRESSED WEAR RESISTANT I R O N ~ H R O M I U M ALLOY WITH HARD PHASE MECHANICALLY ALLOYED SURFACE
B. Martner and E. Friedrich, (Dresden University of Technology, Germany). Production of a novel wear resistant material by impacting hard BC powder into the surface of relatively tough Fe(Cr) powder by ball milling was described. The composite powder was consolidated by hot pressing for a short time to minimize dissolution of BC into the matrix. Stresses and temperature generated during abrasion cause dissolution of BC in the surface layers and ensures the formation of a hard, wear resistant, surface. Process technology, structural changes and wear properties were reported.
LITERATURE
REVIEVt
Steel specimens, prepared from atomized powder were brazed or diffusion bonded in green and sintered conditions. Four brazing alloys were used and the strength and hardness of the joints, as a function of density, were compared with those of the parent metals.
Powder injection moulding COMPARISON OF INJECTION MOULDING OF POWDER/BINDER MIXTURES AND PLASTIC MATERIAL
B.O. Rhee and C.I. Chung, (Rensselaer Polytechnic Inst, Troy, N e w York, USA). It was noted that metal and ceramic materials are often injection moulded on machines designed for use with polymers. Design of machines was discussed with FORMING METHOD FOR A MULTILAYER regard to differences between polymers and PM COMPOSITE MATERIAL PIM feedstocks. Freezing times for both were c o m p a r e d experimentally and L.Y. Li and H.H. Wang, (Qingdao Research analytically. Possible solutions for the problem of premature freezing were Inst of PM, China). Uniaxial compaction for production of discussed. multilayer c o m p o s i t e s was described. STRUCTURE APPROACH TO Applications included oil impregnated INJECTION MOULDING OF POWDERb e a r i n g s and m e c h a n i c a l p a r t s with BINDER MIXTURES medium to high strength.
Joining technology DEVELOPMENT OF TECHNOLOGY FOR LASER WELDING OF SINTERED STEEL PARTS
Y. Mural et al, (Kobe Steel Ltd, Kobe, Japan). The use of C O 2 lasers for joining high C steel was described. Without a filler the joints were reported to contain defects, cracks and blowholes. The filler was selected to control martensite formation, promote deoxidation and fix S and N in the steel. Use of laser welding for 0.8% C steel and 0.6% C low alloy steel was reported. COPPER BRAZING OF PM COMPONENTS TO WROUGHT PARTS
B. Marzella et al, (Clarion Sintered Metals, Ridgeway, USA). The brazing of sintered and wrought steel sub-components was described. The P M steel was Cu infiltrated and it was reported the satisfactory joints were produced. Cost savings were claimed because of the reduction in finishing operations. The powder mixture, control of %C, sintered and green densities and assembly were discussed. JOINING OF IRON RASED PM COMPONENTS BY BRAZING AND DIFFUSION BONDING
B. Clausen and ICA. Thorsen, (Technical University of Denmark, Copenhagen, Denmark).
50 MPR November 1992
R.T. Fox et al, (Rensselaer Polytechnic Inst, Troy, New York, USA). An outline of the objectives of PIM, the production components to c l o s e d i m e n s i o n a l t o l e r a n c e s with u n i f o r m microstructures and improved properties in a cost effective way was presented. The prerequisites for successful PIM, knowledge of the feedstock rheology and the effects of process parameters on the integrity of the part were discussed. Flow behaviour o f a r a n g e of f e e d s t o c k s was d e t e r m i n e d experimentally. Finite element methods were used to analyze the physical and mechanical properties. When applied to actual moulding trails causes of defects can be identified and avoided by proper control of m o u l d i n g p a r a m e t e r s and optimum moulding conditions established. NOVEL BINDER FOR RAPID DEBINDING OF POWDER INJECTION MOULDED SAMPLES
H.H. Andermann and A. van der Biest, (Leuven University, Belgium). The rapid removal of a novel binder from PIM compacts, without wicking or solvent was described. A cylindrical sample 13 mm x 10 ram, made from carbonyl Fe powder w a s d e b o u n d in 5 h o u r s w i t h o u t deformation, results for 316L stainless steel and alumina were also given. NOVEL PROCESS CONTROL METHODS FOR BINDERS BASED ON THERMOSET CONDENSATION RESINS G.M. Brasel and J.E. Duke, (Megamet Industries lnc, St. I~uis, USA).
In-moulding debinding, by the Megamet process, was described with regard to the process controls required. Green compacts were produced without the use of an i n j e c t i o n m o u l d i n g m a c h i n e . The importance of the relationship between the properties of the powder, binder and additives was emphasized. Control of green density was exercised through pressurization control and mould venting in a novel way. EFFECTS OF POWDER CHARACTERISTICS AND DEBINDING CONDITIONS ON DEFORMATION BEHAVIOUR OF INJECTION MOULDED COMPACTS DURING THERMAL DEBINDING
R. Miura and S. Takamori, (Japan Steel Works Ltd, Japan). The causes of distortion during debinding, the weight of the compact and viscous creep, were discussed. A n investigation of deformation in three-point bending of a beam was described. Effects of powder morphology and size distribution, bending moment, solid/binder ratio, heating rate, temperature and atmosphere were outlined. ATMOSPHERE PROCESS FOR THE CONTROL OF CARBON AND OXYGEN CONTENTS DURING DEBINDING OF INJECTION MOULDED STEEL
M.A. Phillips et al, (Liquid Air Corp, Countryside, Illinois, USA). The effects of binder decomposition during debinding in increasing the C content of alloys was discussed. This is partly offset by decarburization by reaction with O. The effect of gas composition of %C in Fe-2%Ni steels was evaluated. Precise C content could be attained by adjusting gas composition and debinding parameters. PROCESS PARAMETERS FOR A FAST CATALYTIC DEBINDING SYSTEM
D. Weinand and M. Blomacher, (BASF AG, Ludwigshafen, Germany). Catalytic debinding of injection moulded parts was discussed and was said to offer advantages over conventional debinding p r o c e s s e s . Th e p r o c e s s p a r a m e t e r s r e l e v a n t to e c o n o m i c a n a l y s i s w e r e investigated. Feedstock theology, thermal history, cycle time and green strength were considered. Continuous and discontinuous debinding were discussed. EVOLUTION OF GASES AND SINTERING BEHAVIOUR IN CARBONYL IRON POWDER FOR INJECTION MOULDING
S. Igarashi et al, Tokyo, Japan). It was noted contains volatile and O and that
(Sumitomo Metal Mining, that carbonyl Fe powder impurities including C, N little research had been