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Atomization of electronic grade solder powders
Powders MICROSTRUCTURE OF POWDERS PRODUCED BY DIFFERENT ATOMIZATION PROCESSES K Halada et al (National Research Inst. for Metals, Tokyo, Japan) A range of powders of non-ferrous metal and alloys were made by various atomization methods. Centrifugally atomized alloy powders had equiaxed dendritic structures, except Zn particles which had facetted surfaces. Dendrite spacing was not in accordance with prediction from the Ranz-Marshall equation and did not depend on method of atomization or conditions. Depth of undercooling was considered to be more significant than heat loss HYBRID MODEL OF GAS ATOMIZATION APPLICATION AND CONTROL SYSTEM P.I. Espina et al (National Inst. for Standards and Technology, Gaithersburg, USA) A model of gas atomization was described which is capable of predicting dynamic response to process parameters. Dual control, separate melting and atomization chambers, heat and mass balances are incorporated in the model. The model was reported to allow prediction of the effects of changes in atomization conditions and may be used for other processes. ATOMIZATION OF ELECTRONIC GRADE SOLDER POWDERS J.J. Dunkley (Atomising Systems Ltd, Sheffield, UK) Atomization methods for production of solder powder were reviewed including twofluid centrifugal, ultrasonic, pressure jet, vibrating orifice and electrostatic atomization processes. ATOMIZATION OF MOLTEN ALUMINIUM USING A THREE FLUIDS METHOD G. Matei, D. Matei (Technical University of Cluj-Napoca, Cluj-Napoca, Romania) A three-fluid process, gas/water/metal, was described for atomization of Al. Process characteristics were studied and compared with two-fluid, gas/metal and water/metal, systems. In the three fluid system the coolig rate is reported to be faster and the particle size to be 10 to 15% smaller than for twofluid atomization systems. CAPABILITIES OF ELECTROMAGNETC SWIRL ATOMIZER FOR PRODUCTION OF SUPERALLOY POWDERS J.C. Gasser, P. Marty (Centre National de la Recherche Scientifique, Grenoble, France) 42
MPR April 1995
The wide range of particle sizes in atomized superalloy powders and the need for a maximum particle size of 50 urn were noted. A novel electromagnetic atomizer was described. The liquid metal aquires angular momentum from a rotating electromagnetic field which allows control of metal to the nozzle. The metal disintegrates under hydrodynamic instability. Performance of the system was evaluated for Sn and Hg. PREPARATION OF MONO-SIZED LEADTIN ALLOY POWDERS BY PULSATED ORIFICE INJECTION METHOD A. Kawasaji et al (Tohoku University, Sendai, Japan) It was reported that the use of pulsated orifice injection resulted in production of uniformly sized powders. The apparatus uses a pulsed piezo-electric actuator each pulse producing one particle. Smooth sperical particles with a small standard deviation were made. Kinetics and the effects of process parameter changes were discussed.
Aluminium
alloys
COMPRESSION TESTING OF SINTERED ALUMINIUM ALLOY POWDER AND FRACTURE CRITERIA G.H. Liaghat (Tarbiat Modarres University, Tehran, Iran) A study of compression testing of sintered Al powder, with the object of prediction fracture, using Kuhn’s technique, was described. It was reported that the plane strain ductility increases with density and that predictions of fracture in cold forming operations could be made. GAS ENTRAPMENT AND EVOLUTION IN TERNARY ALUMINIUM-SILICON ALLOYS J.L. Estrada, J. Duszczyk (Delft University of Technology, Delft, The Netherlands) Aspects of degassing of ternary AlZOat%Si-X alloy powders were investigated at temperatures up to 550°C. It was reported that temperature is the controlling factor for gas desorption and that diffusion of Al through the oxide film is an importamt mechanism. Composition of the oxide film, presence of MgO, requires higher temperatures. Thermodynamics showed that the MgO reacts with water vapour in preference to A1203. ADVANCES IN LIGHTWEIGHT NONFERROUS PM ALLOYS F. Hehmann, F.H. Froes (University of Idaho, Moscow, Idaho, USA) Recent developments in light alloys were reviewed. Ti and Ti intermetallics, Al and Mg alloys and innovations in processing
were considered. PM was shown to allow enhancement in behaviour in a costeffective manner. Some applications in the property determining aerospace industry and the cost-obsessed automotive industry were discussed. ALUMINIUM MATRIX COMPOSITES FOR AUTOMOTIVE APPLICATIONS J. Duszczyk et al (Delft University of Technology, Delft, The Netherlands) Properties of Al alloys for automotive applications were discussed. A study of the effect of 10~01% Sic particles on the properties of Al-20%Si-5%Fe-3%Cu-l%Mg was described. It was reported that thermal expansion was reduced and that hardness, strength, wear resistance were increased at the expense of some loss of ductility at 25°C. HEATING SEQUENCE AND HYDROGEN ELIMINATION IN ALUMINIUM POWDERS J.L. Estrada, J. Duszczyk (Delft University of Technology, Delft, The Netherlands.) Degassing of Al-20%Si-3%Cu- l%Mg powders was investigated up to 550°C. H and Ha0 were the main species evolved. Degassing could be completed only if the contributing chemical reactions could be completed in the applied time. Kinetics could not be explained solely on the basis of thermodynamics, diffusion of Al through the oxide film has to be considered.
Stainless steels NEW WEAR AND CORROSION RESISTANT SINTERED STAINLESS STEELS WITH HIGH NITROGEN CONTENTS N.H. Zheng, M.O. Speidel (Swiss Federal Inst. of Technology, Zurich, Switzerland) The use of PM technology to produce stainless steels with high concentrations of N was discussed with reference to improvements in properties. The process route was described and cornprized powder production, nitriding, consolidation and heat treatment. LOW CYCLE FATIGUE OF A SINTERED AUSTENITIC STAINLESS STEEL B. Lindstedt, B. Karlsson (Chalmers University of Technology, Giiteborg, Sweden) The low cycle fatigue properties of two PM austenitic stainless steels, made by HIP and conventional PM, and a cast/wrought steel, were compared. The cast/wrought steel had a lower N content, otherwise the structures were similar. The cast/wrought steel was shown to have superior resistance to fatigue failure. Crack growth and surface cracks were investigated. Crack initiation was found at oxide particles in the sintered specimens.
MPR April 1995
The wide range of particle sizes in atomized superalloy powders and the need for a maximum particle size of 50 urn were noted. A novel electromagnetic atomizer was described. The liquid metal aquires angular momentum from a rotating electromagnetic field which allows control of metal to the nozzle. The metal disintegrates under hydrodynamic instability. Performance of the system was evaluated for Sn and Hg. PREPARATION OF MONO-SIZED LEADTIN ALLOY POWDERS BY PULSATED ORIFICE INJECTION METHOD A. Kawasaji et al (Tohoku University, Sendai, Japan) It was reported that the use of pulsated orifice injection resulted in production of uniformly sized powders. The apparatus uses a pulsed piezo-electric actuator each pulse producing one particle. Smooth sperical particles with a small standard deviation were made. Kinetics and the effects of process parameter changes were discussed.
Aluminium
alloys
COMPRESSION TESTING OF SINTERED ALUMINIUM ALLOY POWDER AND FRACTURE CRITERIA G.H. Liaghat (Tarbiat Modarres University, Tehran, Iran) A study of compression testing of sintered Al powder, with the object of prediction fracture, using Kuhn’s technique, was described. It was reported that the plane strain ductility increases with density and that predictions of fracture in cold forming operations could be made. GAS ENTRAPMENT AND EVOLUTION IN TERNARY ALUMINIUM-SILICON ALLOYS J.L. Estrada, J. Duszczyk (Delft University of Technology, Delft, The Netherlands) Aspects of degassing of ternary AlZOat%Si-X alloy powders were investigated at temperatures up to 550°C. It was reported that temperature is the controlling factor for gas desorption and that diffusion of Al through the oxide film is an importamt mechanism. Composition of the oxide film, presence of MgO, requires higher temperatures. Thermodynamics showed that the MgO reacts with water vapour in preference to A1203. ADVANCES IN LIGHTWEIGHT NONFERROUS PM ALLOYS F. Hehmann, F.H. Froes (University of Idaho, Moscow, Idaho, USA) Recent developments in light alloys were reviewed. Ti and Ti intermetallics, Al and Mg alloys and innovations in processing
were considered. PM was shown to allow enhancement in behaviour in a costeffective manner. Some applications in the property determining aerospace industry and the cost-obsessed automotive industry were discussed. ALUMINIUM MATRIX COMPOSITES FOR AUTOMOTIVE APPLICATIONS J. Duszczyk et al (Delft University of Technology, Delft, The Netherlands) Properties of Al alloys for automotive applications were discussed. A study of the effect of 10~01% Sic particles on the properties of Al-20%Si-5%Fe-3%Cu-l%Mg was described. It was reported that thermal expansion was reduced and that hardness, strength, wear resistance were increased at the expense of some loss of ductility at 25°C. HEATING SEQUENCE AND HYDROGEN ELIMINATION IN ALUMINIUM POWDERS J.L. Estrada, J. Duszczyk (Delft University of Technology, Delft, The Netherlands.) Degassing of Al-20%Si-3%Cu- l%Mg powders was investigated up to 550°C. H and Ha0 were the main species evolved. Degassing could be completed only if the contributing chemical reactions could be completed in the applied time. Kinetics could not be explained solely on the basis of thermodynamics, diffusion of Al through the oxide film has to be considered.
Stainless steels NEW WEAR AND CORROSION RESISTANT SINTERED STAINLESS STEELS WITH HIGH NITROGEN CONTENTS N.H. Zheng, M.O. Speidel (Swiss Federal Inst. of Technology, Zurich, Switzerland) The use of PM technology to produce stainless steels with high concentrations of N was discussed with reference to improvements in properties. The process route was described and cornprized powder production, nitriding, consolidation and heat treatment. LOW CYCLE FATIGUE OF A SINTERED AUSTENITIC STAINLESS STEEL B. Lindstedt, B. Karlsson (Chalmers University of Technology, Giiteborg, Sweden) The low cycle fatigue properties of two PM austenitic stainless steels, made by HIP and conventional PM, and a cast/wrought steel, were compared. The cast/wrought steel had a lower N content, otherwise the structures were similar. The cast/wrought steel was shown to have superior resistance to fatigue failure. Crack growth and surface cracks were investigated. Crack initiation was found at oxide particles in the sintered specimens.