It was reported that injection moulding had been used to make Ti alloy and stainless steel parts with controlled mechanical and physical properties, selected to match specific applications. Uses included Ti filters and a stainless steel magnetic sensor. Contamination levels and density of the filter were considered. The magnetic sensor was shown and magnetic and corrosion properties were described. MANUFACTURE OF MICROSIZED STRUCTURES BY INJECTION MOULDING
V.Piotter et al. (Forschungszentrum Karlsruhe GmbH, Germany.) Use of injection moulding to make metal and ceramic microparts was discussed. Experimental production of parts 80 pm wide by 500 pm high was reported. No wear was detected on mould parts after 100 moulding cycles. The small parts attained 97% density with 15% linear shrinkage. Examples of parts were shown and the equipment used was described. DESIGN AND MOULDING FLEXIBILITIES FOR WATER-BASED FEEDSTOCKS
C.Ballard et al. (Allied Signal Powder Injection Moulding, USA.) Use of water based binders in injection moulding feedstocks was discussed. It was reported that water-based binders had been used to make a range of stainless steel parts including some with sections less than 1.5 mm thick, high density being attained. The debinding process involves drying and pyrolysis of the binder gelling agents. The low viscosity allows lower moulding temperatures. Materials, processing and performance were reviewed. MICRO-MECHANICAL TESTING OF INJECTION MOULDED IRON ALUMINIDE POWDER COMPACTS
J.C.Foley et al. (Ames Laboratory, USA.) The need for mechanical test methods for small samples was noted. A small punch test was described. This had been developed to test irradiated samples and was used to evaluate effects of porosity and other embrittling defects in injection moulded parts. The test was applied to Fe aluminide specimens in as-synthesized and heat-treated conditions. Analysis of effects of process conditions and chemistry on microstructure and fracture was presented. INJECTION RESISTANT
H.Miura Japan.) 38
MOULDING OF ABRASION FERROUS MATERIALS
et aZ. (Kumamoto
MPR April 1999
An investigation to develop high-performance abrasion resistant ferrous materials, for automotive parts, made by injection moulding was described. The steel powders had additions of TiN or CaF, particles. A C content of 0.4% and of 95% were attained. density Structures comprised ferrite and fine pearlite with uniform distribution of TIN and pores. Swt%TiN gave good wear resistance and 2%CaF, gave good self lubrication. It was suggested that injection moulding has good potential for manufacture of automotive parts. DEVELOPMENT OF CARNUBA WAXBASED VEHICLES FOR LOW PRESSURE INJECTION MOULDING
C.Bezzera et al. (Federal University of CEARA, Brazil.) Limitations to use of carnuba wax in injection moulding binders - low plasticity and narrow freezing range - were noted. A study in which high-density polyethylene, in varying minor amounts, was added to carnuba wax to evaluate the effects on properties was described. Addition of polyethylene to carnuba was reported to give a binder suitable for powder injection moulding.
PROCESSING OF FUNCTIONALLY GRADED MATERIALS BY PM
M.M.Gasik. (Helsinki University of Technology, Helsinki, Finland.) Graded materials were discussed with reference to types differing in composition, phase distribution, porosity and related properties. The presentation considered several systems made using PM methods. Modelling was used to predict three-dimensional property distribution. Principles were reviewed with regard to sintering, properties and applications. MECHANICAL PROPERTIES AND FRACTURE OF LAYERED ALUMINIUM ALLOY-SILICON CARBIDE COMPOSITES
E.J.Lavernia et al. (University of California, Irvine, USA.) It was reported that Al alloy 6061SIC composites, with layered structures, had been made. The layers differed in SIC content. Layer thicknesses were varied. No interfaces between layers were detected. Layers with a high %SiC were preferred sites for crack initiation. The layered structures had high fracture toughness, which was attributed to the properties of the layers with low %‘SiC.
PROCESSING AND CREEP OF GRADED MOLYBDENUM SILICIDESILICON NITRIDE COMPOSITES
V.Sikka et al. (Oak Ridge National Laboratory, USA.) It was noted that MoSi, and S&N, have good oxidation resistance and are chemically compatible. A compositionally graded MoSi,-S&N, composite material was prepared. Processing, structures and properties were described. In particular creep behaviour was investigated and evaluated. In MoSi, creep deformation mode was ductile but in S&N, there was extensive cracking. Possible uses were considered.
Crack detection prevention COMPUTER RESONANT
AIDED TESTING INSPECTION
D.K.Foley. (ITW-Magnaflux, USA.) testing Computer aided was reviewed. Computers can be used to analyse data relating to quality control. A range of non-destructive test methods, including resonant inspection, is amenable to computerization. Resonant inspection has the advantage in that the test system is incorporated in the computer. The hardware is standard units modified to generate and read natural vibrational frequencies found in PM components. DETECTION OF FLAWS IN POWDER METAL COMPONENTS BY SONIC FREQUENCY ANALYSIS
G.Stultz, K.Byrd. (Federal Mogul Sintered Products, USA.) The demands imposed on PM parts makers to supply defect free products was emphasized. The need to detect defects generated during compaction was noted. Detection methods were discussed and it was shown that these are mostly subjective and are time consuming. Acoustic analysis, by computer, of the sounds emitted when a part is struck with a hammer was shown to be effective in crack detection.
Atomization PRODUCTION OF ULTRA-CLEAN ATOMIZED POWDER BY USE OF PLASMA HEATED TUNDISH
T.A.Tingskog. (ANVAL Inc, USA.) It was reported that plasma heating of the tundish in a gas atomizer resulted in reduced concentrations of non-metallic inclusions in metal powders. Design details, operating experiences and production results were presented.