| The effects of gas atomization variables on the particle size distribution and particle shape of Al alloys were studied with the self-manufactued high pressure gas atomizer at the range of melt flow rate (Mm) of 1.8-8.0 ㎏/min and gas flow rate (㎎) of 1.7-3.0 ㎏/min. In these ranges, powders of mass mean diameter of 40-100㎛, and geometric standard deviation of 1.2-2.8 were obtained. The ratio of ㎎/Mn seemed to be the dominant factor determining the particle size distribution by affecting the prefilming behavior of the melt: as the ratio of ㎎/Mm increased, the melt prefilm seemed to become thinner, and finer particles were produced. Liquid state volume contraction, oxidation and collision between powders were the main factors determining the powder shape. The cooling rate of 270 mesh powders manufactured in this study was estimated to exceed 5×10⁴K/sec. |
|
