Optimization of process parameters for preparing honodisperse particles by pulsated orifice injection method

Monosized spherical powders of Pb-Sn alloy were prepared by pulsated orifice injection method (POIM). The apparatus was devised for injecting molten metal from a small orifice by a clipping action of a pressure transmitting diaphragm driven by a piezoelectric actuater. Each pulse pressure, induced by the displacement of the diaphragm, produced one liquid droplet having a size almost equal to the orifice diameter. The effect of the process parameters of waveform, characterized as rise time, hold time and fall time, on the particle formation and size scattering has been discussed. The shape of the obtained particles is spherical with smooth surface covered with very thin layer of SnO₂ which is less than 10 Ȧ as detected by auger electron spectrocopy.