Influence of Melt Dispersing Parameters on the Morphology, Structure, and Particle Size of the Water Atomized Aluminium Powders

Abstract

The water atomized powders of aluminum and aluminum alloys, produced under the water pressure of 2.0−16.0 MPa and at the temperature of coalesced melt of 690−1350 °C, were studied. It was established that the melt temperature and the energy carrier pressure (within above ranges) almost do not affect the shape of similar-in-size particles and their surface morphology. The particle size is a key parameter in shaping and structure formation of the atomized powders. The heat transfer process occurs in the film boiling conditions because of the high temperature head (380−935 °C) and the appropriate heat-flow rate, considerably exceeding its critical value. It was established that the heat transfer coefficient (under 10−14 MPa pressure by energy carrier) changes from 10⁴ to 4 x 10⁴ W/(m² • °C) with a deviation of ±5.5% from the average when the heat-flow rate ranges from 10⁷ to 5 • 10⁷ W/m², accordingly. This technique to determine the heat transfer coefficient is based on the cooling rate calculation by dendritic parameter, which allows increasing the accuracy of calculations.