Study on Mechanism of Preparing Spherical Aluminum Powder by Evaporative Condensation

Abstract

The nucleation of aluminum vapor in phase transition and its condensation were studied at 15 pa. The impacts of the condensing conditions, including the aluminum partial pressure, temperature, and condensation zone temperature gradient, on aluminum vapor nucleation and condensation, were discussed from the point of view of atom collision. Aluminum powder and beads were produced under different conditions and characterized by scanning electron microscopy (SEM) and the proportion of fine powder. The rate of evaporation increases with increasing temperature and evaporation surface area. The condensation position at which the aluminum vapor becomes solid is further away from the evaporation surface area, with the temperature of the heating source increasing. It can benefit to the condensation and crystallization of aluminum vapor by appropriately increasing the condensing zone’s crucible diameter and temperature gradient.