- Email: [email protected]
Novel sinter-bonding to coat cermets onto steel for wear resistance
PHYSICAL PROPERTIES OF INJECTION MOULDED STEELS M.BlGmacher et al. (BASF AG, Germany.) A study of the dynamic properties of injection moulded steels was described. Data concerning dynamic tensile properties were presented and compared with static properties, taking metallographic structure into the analysis. Previous investigations were reviewed. SUITABILITY OF MECHANICALLY ALLOYED POWDERS FOR INJECTION MOULDING J.W.Newkirk et al. (University of Missouri, USA.) Use of mechanically alloyed powders for injection moulding was investigated. It was shown that parts made from MA powders had a finer grain size than alloys made from conventionally processed powders. MA powders required a lower sintering temperature. The possibility of contamination from the milling tools was noted. Mechanical properties of parts made from MA and conventional powders were compared. Contamination was examined to determine if this added to the process complexity and costs. A ‘window’ for MIM processing of MA powders was established.
Sinter bonding GROWTH OF PM MATERIALS IN NONTRADITIONAL AREAS R.G.Iacocca, R.M.German. (Pennsylvania State University, USA.) Non-traditional use of metal powders was discussed. Quantities used are small compared with parts production by pressand-sinter methods. The paper concentrated on applications in soldering and brazing. In particular the powder characteristics required and application of sintering theory were considered. DEVELOPMENT OF PM SINTERBRAZED PLANETARY CARRIER T.Okamura et al. (Sumitomo Electric Industries, Japan.) Parts for automotive transmission were reviewed with particular reference to the carrier for pinion gears. On four-wheel drive vehicles this has had to be made as a casting which required extensive machining. The paper reported on the use of PM to make this part. The method used sinterbrazing to join sub-parts to yield a nearnet-shape. Finite element analysis was used in the development. NOVEL SINTER-BONDING TO COAT CERMETS ONTO STEEL FOR WEAR RESISTANCE R.M.German et al. (Pennsylvania University, USA.)
State
Reactive sintering, to bond ternary boride cermets onto steel substrates, was described. The process synthesizes hard phases in situ and bonds these to the substrate. The steel is coated with a mixture of elemental and boride precursor powders, which, by heat treatment, synthesize the cermet and by liquid phase sintering bonds it to the steel surface. The technique was reported to yield a defect-free interface. A model was developed and the process was monitored. The wear resistance was reported to compare favourably with other materials. not compaction processing HOT SHOCK WAVE COMPACTION OF COATED TUNGSTEN BASE POWDERS N.M.Chikradze et al. (Academy of Sciences, Georgia.) It was reported that shock wave compaction had been used to consolidate W powders coated with Ni or Ni-Cr, and WC coated with Co. Near maximum density and high hardness were attained. Microscopy showed that W and WC particles fragmented during compaction. Property/structure relationships were discussed. OPTIMIZATION OF COMBUSTION SYNTHESIS/QUASI ISOSTATIC PRESSING OF TITANIUM CARBIDE CERMETS R.Raman et al. (Ceracon Inc, USA.) Combination of combustion synthesis with quasi-isostatic pressing was discussed. It was reported that the combined technique had been used to prepare high density Ti-(Ti-Ni) cermets with controlled structure and properties. A model for consolidation of Ti-C-Ni powders was described. Parameters were measured by experiment. Aspects of the modelling and process optimization were discussed. HOT PRESSING OF COBALT POWDERS D.Adam et al. (Swiss Federal Inst. of Technology, Switzerland.) Hot pressing of submicron Co powders, at 800 or 900°C and various pressure regimes, was investigated with respect to final structure and hardness. It was shown that a fine dispersion of oxide particles is important for attainment of a fine structure and high hardness. The results were correlated with models. EURO PIM ‘97. The Abstracts which follow are from papers presented at the First European Symposium on Powder Injection Moulding, which was held in Munich, Germany, in October 1997.
EFFECT OF INTERPARTICLE DISTANCE ON RHEOLOGICAL PROPERTIES OF CERAMIC FORMULATION S.Novak et al. (Joseph Stephan Inst., Slovenia.) The effects of distribution of interparticle distances on mechanical properties of green moulded compacts during debinding were discussed. A computer simulation was used to model materials with differing solids contents and particle packing. Real input data for particle size distribution of Al,O, powder and an Al,O,-paraffin feedstock were analysed. Particle separation, derived from liquid film thickness, was correlated with rheological and mechanical properties of green parts during debinding. METAL INJECTION MOULDING USING THERMAL DEBINDING T.L.King. (Advanced Materials Technologies Pte. Ltd, Singapore.) Binders in MIM and debinding were discussed with regard to the strengths and weaknesses of systems, methods of debinding and criteria for selection of binder taking mass production into account. It was reported that a novel, patented, cost-effective thermal debinding system had been developed. Flow rheology, recyclability of feedstock, dimensional stability of green and sintered parts, and the thermal debinding technology formed a major part of the paper. MAGNETIC MOULD CLAMPING A.Vernikov. (Walker Magnetics Group Walker-Hag, The Netherlands.) It was noted that magnetic clamping of MIM moulds provides uniform force, minimum deformation and good access to the parts. It was reported that a novel clamping system had been developed which allowed rapid mould handling, reduced platen deformation and increased machine capacity. Strong permanent magnets hold the mould parts secure. Microprocessor control can be fully integrated into the system. COMPUTATIONAL MODELLING OF DENSIFICATION AFTER POWDER INJECTION MOULDING J.C.Gelin et al. (University de FrancheCompte, France.) Densification of MIM parts was discussed with reference to the need to optimize all stages in the process in order to ensure part quality. A thermomechanical model and numerical simulation of densification were proposed. The model takes initial feedstock state and uses conservation of mass and momentum to evaluate evolution of part shape and density in two stages. One stage is for rapid densification in the of density 64% to 90%. range
MPR October 1998 39
Sinter bonding GROWTH OF PM MATERIALS IN NONTRADITIONAL AREAS R.G.Iacocca, R.M.German. (Pennsylvania State University, USA.) Non-traditional use of metal powders was discussed. Quantities used are small compared with parts production by pressand-sinter methods. The paper concentrated on applications in soldering and brazing. In particular the powder characteristics required and application of sintering theory were considered. DEVELOPMENT OF PM SINTERBRAZED PLANETARY CARRIER T.Okamura et al. (Sumitomo Electric Industries, Japan.) Parts for automotive transmission were reviewed with particular reference to the carrier for pinion gears. On four-wheel drive vehicles this has had to be made as a casting which required extensive machining. The paper reported on the use of PM to make this part. The method used sinterbrazing to join sub-parts to yield a nearnet-shape. Finite element analysis was used in the development. NOVEL SINTER-BONDING TO COAT CERMETS ONTO STEEL FOR WEAR RESISTANCE R.M.German et al. (Pennsylvania University, USA.)
State
Reactive sintering, to bond ternary boride cermets onto steel substrates, was described. The process synthesizes hard phases in situ and bonds these to the substrate. The steel is coated with a mixture of elemental and boride precursor powders, which, by heat treatment, synthesize the cermet and by liquid phase sintering bonds it to the steel surface. The technique was reported to yield a defect-free interface. A model was developed and the process was monitored. The wear resistance was reported to compare favourably with other materials. not compaction processing HOT SHOCK WAVE COMPACTION OF COATED TUNGSTEN BASE POWDERS N.M.Chikradze et al. (Academy of Sciences, Georgia.) It was reported that shock wave compaction had been used to consolidate W powders coated with Ni or Ni-Cr, and WC coated with Co. Near maximum density and high hardness were attained. Microscopy showed that W and WC particles fragmented during compaction. Property/structure relationships were discussed. OPTIMIZATION OF COMBUSTION SYNTHESIS/QUASI ISOSTATIC PRESSING OF TITANIUM CARBIDE CERMETS R.Raman et al. (Ceracon Inc, USA.) Combination of combustion synthesis with quasi-isostatic pressing was discussed. It was reported that the combined technique had been used to prepare high density Ti-(Ti-Ni) cermets with controlled structure and properties. A model for consolidation of Ti-C-Ni powders was described. Parameters were measured by experiment. Aspects of the modelling and process optimization were discussed. HOT PRESSING OF COBALT POWDERS D.Adam et al. (Swiss Federal Inst. of Technology, Switzerland.) Hot pressing of submicron Co powders, at 800 or 900°C and various pressure regimes, was investigated with respect to final structure and hardness. It was shown that a fine dispersion of oxide particles is important for attainment of a fine structure and high hardness. The results were correlated with models. EURO PIM ‘97. The Abstracts which follow are from papers presented at the First European Symposium on Powder Injection Moulding, which was held in Munich, Germany, in October 1997.
EFFECT OF INTERPARTICLE DISTANCE ON RHEOLOGICAL PROPERTIES OF CERAMIC FORMULATION S.Novak et al. (Joseph Stephan Inst., Slovenia.) The effects of distribution of interparticle distances on mechanical properties of green moulded compacts during debinding were discussed. A computer simulation was used to model materials with differing solids contents and particle packing. Real input data for particle size distribution of Al,O, powder and an Al,O,-paraffin feedstock were analysed. Particle separation, derived from liquid film thickness, was correlated with rheological and mechanical properties of green parts during debinding. METAL INJECTION MOULDING USING THERMAL DEBINDING T.L.King. (Advanced Materials Technologies Pte. Ltd, Singapore.) Binders in MIM and debinding were discussed with regard to the strengths and weaknesses of systems, methods of debinding and criteria for selection of binder taking mass production into account. It was reported that a novel, patented, cost-effective thermal debinding system had been developed. Flow rheology, recyclability of feedstock, dimensional stability of green and sintered parts, and the thermal debinding technology formed a major part of the paper. MAGNETIC MOULD CLAMPING A.Vernikov. (Walker Magnetics Group Walker-Hag, The Netherlands.) It was noted that magnetic clamping of MIM moulds provides uniform force, minimum deformation and good access to the parts. It was reported that a novel clamping system had been developed which allowed rapid mould handling, reduced platen deformation and increased machine capacity. Strong permanent magnets hold the mould parts secure. Microprocessor control can be fully integrated into the system. COMPUTATIONAL MODELLING OF DENSIFICATION AFTER POWDER INJECTION MOULDING J.C.Gelin et al. (University de FrancheCompte, France.) Densification of MIM parts was discussed with reference to the need to optimize all stages in the process in order to ensure part quality. A thermomechanical model and numerical simulation of densification were proposed. The model takes initial feedstock state and uses conservation of mass and momentum to evaluate evolution of part shape and density in two stages. One stage is for rapid densification in the of density 64% to 90%. range
MPR October 1998 39