Abstract
Size-distribution and locational distribution were investigated for zinc powders produced by the centrifugal atomization with various diameters of the rotating disk, revolution rates and pouring rates of molten zinc. During atomization surface temperature of the rotating disk and atomizing state were monitored by use of a thermoviewer and a VTR camera. The monitoring of the atomization showed the necessity of heating the surface of the disk up to the melting temperature of the metal to obtain fine powders. The relation of the mean diameters of obtained powders to the rotating conditions was found that the mean diameter in dimensionless form was proportional to the inverse square of Weber number. The produced powders showed bimodal size-distributions, which corresponded to the direct-drop-formation breakup.
Finer powders were located nearer to the center of the atomizing chamber, and the pouring rate did not affect the size distributions of powders collected on the bottom of the chamber. Flight of finer powders made by the direct-drop-formation breakup depended on the size of the powder and on the rotating conditions. When the pouring rates were too high an instable columnar breakup occurred to make coarse powders which were flown far-ther.
