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 effects of impingement of molten spray on the substrate to control of particle size and size distribution of the metal powder. The idea is to combine the classification process with atomization process in the metal powder production. Result shows that a significant reduction of the particle size occurred when the substrate was placed in the molten spray with different transmission ratio. The mean particle size was lowered to 8.0μm under a low transmission ratio of the spray jet using 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. The particle size was further reduced to 6.72μm ∼ 6.98μm when the disk-type substrate was placed in the spray flow field. It was found that the particle size with the disk type substrate because the transmission ratio of the disk type substrate was lower than that of the ring type substrate. The percentage of small particles (i.e., V_15-) were higher than 60% and the percentages of V_25-45 were lowered to 4.19% and 0.37% when the disk-type substrate was placed at Z=150mm and Z=200mm, respectively. It indicated that almost all of the particles were below 25μm under these conditions. Hence this technique can be used to control of the particle size in the production of the ultra-fine metal powder.