Particle size of atomized alloy powder prepared by using a confined-type atomizing nozzle

Synopsis : The influences of the gas jet spouted from the atomizing nozzles , gas and metal flow rare ratio and gas pressure on the median diameter and particle size distribution were investigated. The median diameter of atomi zed powder varies in proportion to the square root of M-l/M-g Value when th e atomized powder was formed at various melt or gas flow rate under the sam e other conditions. The median diameter varies inversely proportional to th e mean gas velocity when the powder was atomized using Various atomizing no zzles which have different dimension i.e. the apex angle and gas jet nozzle configuration. Approximately the same median diameter powder was obtained at the same gas Row rate regardless of the gas jet pressure. An experimenta l formula was obtained as follows; d(p)(50)/D-l = 63.6 root (M-l/M-g) . (sigma(l)/(D-l . rho(l) . V-g(2))) . ( nu(l)/nu(g)) where, d(p)(50): Median diameter of atomized powder (m), D-l: Diameter of m elt delivery tube (m), M-l: Mass flow rate of molten metal (kg/s), M-g: Mas s flow rate of atomizing gas (kg/s), sigma(l): Surface tension of molten me tal (N/m), rho(l): Density of molten metal (kg/m(3)), V-g: Gas velocity (m/ s), v(l): Kinematic viscosity of molten metal (m(2)/s), v(g): Kinematic vis cosity of atomizing gas (m(2)/s). The fraction of coarse powder increased w hen the atomization was performed with a concave gas velocity distribution compared to a convex one which is the ordinary case. The calculated particl e size distribution coincides roughly with the experimental results. It was shown that the particle size distribution depends on the gas velocity dist ribution.