Effect of the Parameters of Melt Dispersion Process on the Morphology, Structure, and Particle Size of Water-Atomized Aluminum Powders

Water atomized powders of aluminum and aluminum alloys produced at a melt temperature of 690−1350°C and a water pressure of 2.0−16.0 MPa are studied. It is established that the melt temperature and the water pressure in these ranges hardly affect the shape of particles similar in size and their surface geometry. The particle size is a key parameter in the shaping and structure formation of particles. The heat transfer process occurs in film boiling conditions because of high temperature difference at 380−935°C and heat flux much higher than critical. It is established that the heat transfer coefficient at a water pressure of 10−14 MPa changes from 104 to 4 · 104 W/(m2 · °C) with a standard deviation of ±5.5% as the heat flux changes from 107 to 5 · 107 W/m2. This technique to determine the heat transfer coefficient involves the calculation of the cooling rate using the dendritic parameter, which allows increasing the accuracy of calculation.