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Injection moulding of tungsten carbide-cobalt
uum arc deposition with high deposition rates. A study of deposition rate, surface morphology and microstructure of MO coatings on various substrates was described. It was reported that morphology, structure, adhesion and coating thickness could be controlled. CORROSION OF MOLYBDENUM TUNGSTEN ALLOYS IN MOLTEN AND ZINC-ALUMINIUM
J.C.Gelin et al. (University de FrancheComte, France.) Densification of MIM parts was discussed with reference to the need to optimize all process stages in order to ensure part quality. A thermo-mechanical model and numerical simulation of densification were proposed. The model takes initial feedstock state and uses conservation of mass and motion equations to evaluate evolution of part shape and density in two stages. One stage is at 64 to 90% density and is for rapid densification, which slows down above 90%. The material behaviour is represented by a non-linear viscous model. The simulation is based on a transient algorithm for viscous behaviour with time. Temperature variation was considered. Some examples were given.
AND ZINC
H.P.Martinz et al. (Plansee AG, Reutte, Austria.) Corrosion of MO, MO-30%W, W and W-l%La,O, in molten Zn and Zn-5%Al was investigated. Only W and W-La,O, were resistant to both melts. MO-W was not attacked by Zn but was by Zn-Al. Pure MO was attacked by molten Zn very aggressively. It was considered that W-l%La,Os is a good material for use in molten Zn-Al.
CHARACTERIZATION BY MICROCOMPUTER I
EURO PIM’97. The following Abstracts are from papers which were presented at the First European Symposium on Powder Injection Moulding, which was held in Munich, Germany, in October 1997.
Applications PROPERTIES OF MATERIALS STRUCTURAL PARTS MADE METAL INJECTION MOULDING
AND BY
H.Cohrt. (Schunk Sintermetalltechnik GmbH, Germany.) MIM was discussed with respect to properties, notably of steels, part shape and structure. Principles of microstructure evolution in low alloy steels were outlined and correlated with mechanical properties. Surface condition and tolerances were considered. PRODUCTION MOULDING POWDER
AND INJECTION OF NICKEL ALUMINIDE
H.Paisley et al. (Brunel University, Uxbridge, Middlesex, UK.) It was reported that novel gas atomization, injection moulding and HIP had been used to make Ni aluminide materials. Properties were measured. Laboratory experiments were transferred to make real near-net-shape parts, some with fibre reinforcements. Properties of HIP Ni-8.3wt%Al-7.4%Cr0.09%ZrO.O3%B were compared with published data for the alloy.
Sintering COMPUTATIONAL DENSIFICATION INJECTION
MODELLING AFTER POWDER MOULDING
38 MPR June 1998
OF
, J
OF PM PARTS TOMOGRAPHY
K.Pischang et al. (Dresden University of Technology, Dresden, Germany.) It was noted that characterization of a finished PM part may require its destruction and it is not certain where a defect may have arisen. It was shown that computerized tomography provides rapid characterization at each process step by visualization of inner structures. Study of as-moulded, de-bound and sintered parts was described. ‘State-of-theart’ computer tomography, possibilities and limitations were discussed. MULTIPHASE MODELLING
FLOW PIM
APPROACH
IN
MANUFACTURE OF CERAMIC CUTTERS BY INJECTION MOULDING
Z.Rak, G.Snijders. (Netherlands Energy Research Foundation, The Netherlands.) It was reported that thin ceramic cutters had been manufactured by injection moulding from ZrO,, partially stabilized by Y,O,, with a polyacetate binder. Compacts were debound at 101 to 115°C for 1 to 2 hours. Sintered blades were machined to final shape and heat treated to improve properties. Influence of process parameters on product quality was discussed and comparison was made with ceramic knives made by other PM processes. AQUEOUS CERAMICS
INJECTION
MOULDING
OF
R.J.Huzzard, S.Blackburn. (University of Birmingham, Birmingham, UK.) It was reported that reactive Also, of mean particle size 0.5 pm had been injection moulded with a hydroxypropylmethyl cellulose binder under a range of conditions. A ‘window’ for production of defect-free parts was identified. Debinding was enhanced by microwave drying. Capillary rheometry was used to study the rheological properties of the feedstock which were correlated with defect generation and product quality.
TO
M.Dutilly, J.C.Gelin. (University of Franche-Comte, France.) Modelling of injection moulding was discussed with regard to problems introduced by phase separation, which may lead to distortion and defects. A mixture theory was used in modelling injection of feedstock. This allows description of variation of feedstock composition as a function of position in the die and process variables. A momentum exchange term is introduced in the model and finite element methods were used. Material parameters were determined experimentally and results for a selected mould were presented. WEAR OF MOUTHPIECE FERRITE PRODUCTS
was investigated for MgZn-, MgCo- and NiZn-ferrites. Lubricants were evaluated with regard to reduction of wear.
SHAPING
L.Letyuk et al. (Moscow Inst. of Steel and Alloys, Moscow, Russia.) Wear of nozzles in moulding machines, caused by abrasion by metallic particles in the feedstock, was discussed. The results in the case of long tubular products are that dimensions may change and density inhomogeneities be introduced. Wear of nozzles
INJECTION TUNGSTEN
MOULDING OF CARBIDE-COBALT
J.Bruhn, B.Terselius. (Hogskolan Kristianstad, Sweden.) Injection moulding of submicron WC-lO%Co hardmetal, with a waxstearic acid-polymer binder was investigated. Scanning electron microscopy and rheometry were used to assess particle dispersion and flow properties of the feedstock. Thermogravimetry was used to monitor thermal debinding and compacts were sintered. Structure and properties were shown to be similar to submicron WC-Co hardmetals produced by conventional PM methods. r----
EURO PM’97. The follow are of papers European Conference Structural Materials in Munich, Germany,
_____.-
Abstracts which presented at the on Advances in which was held in October 1997. A
Finishing JOINING STEELS
OF PM AND CONVENTIONAL BY LASER WELDING
~
J.C.Gelin et al. (University de FrancheComte, France.) Densification of MIM parts was discussed with reference to the need to optimize all process stages in order to ensure part quality. A thermo-mechanical model and numerical simulation of densification were proposed. The model takes initial feedstock state and uses conservation of mass and motion equations to evaluate evolution of part shape and density in two stages. One stage is at 64 to 90% density and is for rapid densification, which slows down above 90%. The material behaviour is represented by a non-linear viscous model. The simulation is based on a transient algorithm for viscous behaviour with time. Temperature variation was considered. Some examples were given.
AND ZINC
H.P.Martinz et al. (Plansee AG, Reutte, Austria.) Corrosion of MO, MO-30%W, W and W-l%La,O, in molten Zn and Zn-5%Al was investigated. Only W and W-La,O, were resistant to both melts. MO-W was not attacked by Zn but was by Zn-Al. Pure MO was attacked by molten Zn very aggressively. It was considered that W-l%La,Os is a good material for use in molten Zn-Al.
CHARACTERIZATION BY MICROCOMPUTER I
EURO PIM’97. The following Abstracts are from papers which were presented at the First European Symposium on Powder Injection Moulding, which was held in Munich, Germany, in October 1997.
Applications PROPERTIES OF MATERIALS STRUCTURAL PARTS MADE METAL INJECTION MOULDING
AND BY
H.Cohrt. (Schunk Sintermetalltechnik GmbH, Germany.) MIM was discussed with respect to properties, notably of steels, part shape and structure. Principles of microstructure evolution in low alloy steels were outlined and correlated with mechanical properties. Surface condition and tolerances were considered. PRODUCTION MOULDING POWDER
AND INJECTION OF NICKEL ALUMINIDE
H.Paisley et al. (Brunel University, Uxbridge, Middlesex, UK.) It was reported that novel gas atomization, injection moulding and HIP had been used to make Ni aluminide materials. Properties were measured. Laboratory experiments were transferred to make real near-net-shape parts, some with fibre reinforcements. Properties of HIP Ni-8.3wt%Al-7.4%Cr0.09%ZrO.O3%B were compared with published data for the alloy.
Sintering COMPUTATIONAL DENSIFICATION INJECTION
MODELLING AFTER POWDER MOULDING
38 MPR June 1998
OF
, J
OF PM PARTS TOMOGRAPHY
K.Pischang et al. (Dresden University of Technology, Dresden, Germany.) It was noted that characterization of a finished PM part may require its destruction and it is not certain where a defect may have arisen. It was shown that computerized tomography provides rapid characterization at each process step by visualization of inner structures. Study of as-moulded, de-bound and sintered parts was described. ‘State-of-theart’ computer tomography, possibilities and limitations were discussed. MULTIPHASE MODELLING
FLOW PIM
APPROACH
IN
MANUFACTURE OF CERAMIC CUTTERS BY INJECTION MOULDING
Z.Rak, G.Snijders. (Netherlands Energy Research Foundation, The Netherlands.) It was reported that thin ceramic cutters had been manufactured by injection moulding from ZrO,, partially stabilized by Y,O,, with a polyacetate binder. Compacts were debound at 101 to 115°C for 1 to 2 hours. Sintered blades were machined to final shape and heat treated to improve properties. Influence of process parameters on product quality was discussed and comparison was made with ceramic knives made by other PM processes. AQUEOUS CERAMICS
INJECTION
MOULDING
OF
R.J.Huzzard, S.Blackburn. (University of Birmingham, Birmingham, UK.) It was reported that reactive Also, of mean particle size 0.5 pm had been injection moulded with a hydroxypropylmethyl cellulose binder under a range of conditions. A ‘window’ for production of defect-free parts was identified. Debinding was enhanced by microwave drying. Capillary rheometry was used to study the rheological properties of the feedstock which were correlated with defect generation and product quality.
TO
M.Dutilly, J.C.Gelin. (University of Franche-Comte, France.) Modelling of injection moulding was discussed with regard to problems introduced by phase separation, which may lead to distortion and defects. A mixture theory was used in modelling injection of feedstock. This allows description of variation of feedstock composition as a function of position in the die and process variables. A momentum exchange term is introduced in the model and finite element methods were used. Material parameters were determined experimentally and results for a selected mould were presented. WEAR OF MOUTHPIECE FERRITE PRODUCTS
was investigated for MgZn-, MgCo- and NiZn-ferrites. Lubricants were evaluated with regard to reduction of wear.
SHAPING
L.Letyuk et al. (Moscow Inst. of Steel and Alloys, Moscow, Russia.) Wear of nozzles in moulding machines, caused by abrasion by metallic particles in the feedstock, was discussed. The results in the case of long tubular products are that dimensions may change and density inhomogeneities be introduced. Wear of nozzles
INJECTION TUNGSTEN
MOULDING OF CARBIDE-COBALT
J.Bruhn, B.Terselius. (Hogskolan Kristianstad, Sweden.) Injection moulding of submicron WC-lO%Co hardmetal, with a waxstearic acid-polymer binder was investigated. Scanning electron microscopy and rheometry were used to assess particle dispersion and flow properties of the feedstock. Thermogravimetry was used to monitor thermal debinding and compacts were sintered. Structure and properties were shown to be similar to submicron WC-Co hardmetals produced by conventional PM methods. r----
EURO PM’97. The follow are of papers European Conference Structural Materials in Munich, Germany,
_____.-
Abstracts which presented at the on Advances in which was held in October 1997. A
Finishing JOINING STEELS
OF PM AND CONVENTIONAL BY LASER WELDING
~