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An experimental centrifugal atomiser was used to study the manufacture of zinc powder. Melt temperature, melt flow rate, rotating speed and diameter of the atomising disc, are operating parameters that were varied, and their effects on powder quality and yield were observed. The median particle size and the particle size distribution tended to be better, i.e. smaller and narrower, with increasing rotating speed, melting temperature, and atomising disc size. With decreasing melt flow rate, the median particle size decrease and the particle size distribution is similar, all curves are almost overlapping. The yield of zinc powder increased with rotating speed and disc size, and decreased with melt flow rate. Apparent densities of zinc powder were in the range from 1.65 to 2.51 g/cm 3 . In SEM micrographs most zinc particles were irregular in shape, and the particle structure was mainly cellular based on optical imaging after etching of a polished surface.

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The purpose of this paper is to demonstrate the influence of atomizer disc shape and size on the characteristics of zinc metal powder produced by centrifugal atomization. Two types of atomizer disc were employed, the flat disc and the cup-shaped disc with diameters of 30 and 50 mm for each type. The atomization was carried out in ambient air atmosphere, at pouring melt temperature of 550°C. The molten zinc was fed by gravity through a 1.0 mm nozzle with melt flow rate of approximately 50 kg/hr onto the atomizer disc spinning with a speed of 30,000 rpm. It was found that, the median particle size of zinc metal powder was decreased with increasing atomizer disc size. The cup-shaped disc gave better powder production with smaller particle median size and higher production yield. SEM images revealed that most zinc metal particles were irregular, ligament and elongated flakes. The oxygen in air might inhibit the spheroidization of melt droplet during solidification.