Apparatus and method for the formation of uniform spherical particles

摘要

The present invention relates to an atomization apparatus and method for the formation of substantially uniform, at least nearly spherical particles, particularly for the formation of metal particles. The present invention provides an atomization apparatus having a nozzle positioned at the bottom of a cooling chamber. Rayleigh wave instability may be induced by imparting vibrations to a stream of molten material which is released in an upward direction. This produces uniform droplets having an initial velocity sufficient to increase the residence time of the droplets in an inert atmosphere. The parabolic trajectory of the droplets over a 2 m vertical displacement is approximately five times longer than a freefall, thus significantly increasing the cooling time without increasing the cooling chamber height. Further the kinetic energy of each droplet is much lower throughout its trajectory which serves to improve the formation of spherical shaped particles and to lower the impact velocity. Vibrations imparted to the nozzle transversely to the fluid stream cause a periodic dispersion of the sequential droplet trajectories preventing droplets from impacting each other or coalescing.