Effects of Substrate Geometry on Performance of Twin-Fluid Atomizer in Metal Powder Production

Uniform and spherical metal powders have been widely used in many industrial applications. This paper investigates the control of particle size and size distribution by the impingement of the molten spray on the substrate with different geometries. The idea is to combine the atomization process with the classification process. Result shows that a significant reduction of the particle size occurred when the substrate was placed in the spray jet. The mean particle size was lowered to 8.0μm with a low transmission ratio of the spray jet in the existence of the ring type substrate. The particle size increased from 8.78μm to 12.67μm as the transmission ratio was increased from 13.92% to 75.80%. The reduction in particle size was due to the effect of the blockage of the substrate on the spray. The particle size increased from 6.72μm to 6.98μm when the disk-type substrate was placed at Z = 150mm and 200mm, respectively. The particle size of this case was smaller than the case with ring type substrate because the transmission ratio of the disk type substrate was lower. The percentage of small particles (i.e., V15-) were higher than 60% and the percentages of V25-45 were 4.19% and 0.37% when the disk-type substrate was placed at Z=150mm and Z=200mm, respectively, indicating that almost all of the particles were below 25μm under these conditions. Hence this technique is very effective in controlling the particle size in the metal powder production.