Characterisation of metal powders generated by a pressure-gas-atomiser

Pressure-gas-atomisation is a relatively new method to produce metal powder by combining two atomisation principles. First, a liquid hollow cone film is created by a pressure-swirl-atomiser which is subsequently atomised by concentric gas jets to produce fine spherical droplets. Normally, gas atomised powder shows droplets with a lot of satellites sticking on the droplets surface. Avoiding those satellites needs a reduction of circulating gas flow inside the spray chamber. Pure molten tin was used to study the characteristics of this type of melt atomisation. The powders were analysed by laser diffraction and scanning electron microscopy. The results show the effect of atomiser design, gas-to-metal ratio, melt superheat, and gas recirculation on the mass median diameter, the geometric standard deviation, and the particle shape.