Preparation of fine metal and alloy powders via gas solid dual phase atomisation technology

Abstract

The gas and solid dual phase atomisation technology has been developed with a high velocity gas jet stream containing solid particles as the atomisation medium. Particles of NaCl, Al–20Si alloy and SiC are adopted as the alternative atomisation medium to produce fine powders of stainless steel, Al–20Si alloy and 6061Al alloy respectively. Metal and alloy powders with a finer particle size, a narrower size distribution, a higher cooling rate and a better sphericity than those of the conventional gas atomisation technology have been produced by this technique. The influences of the three atomisation media on the particle size and shape of the as prepared powders are thoroughly analysed and their advantages are outlined. Owing to high solubility in water, NaCl particles entrapped in metallic powders can be completely cleared away by water washing and thus, have no negative effect on the as prepared powders. Because SiC particles can be integrated into 6061Al alloy as the reinforcement, no impurities are introduced in the whole process and thus, this atomisation medium has no influence on the as prepared powders. The gas and solid dual phase atomisation technology has been proved to be a very simple and convenient, the most important environment friendly and low cost method for the production of metallic powders demanded in modern industries.