Modeling of heat flow and solidification during atomization and spray deposition processing

A mathematical model of the spray deposition process, based on heat flow analysis during solidification of droplets, as well as that of the spray deposit, is presented. The heat flow during cooling of droplets is analyzed in five distinct stages. A one-dimensional heat transfer model, using a finite difference method, is used to calculate the temperature of the deposit. The results indicate that the cooling rate of a wide size range of droplets of Al-4.5 Cu alloy in the spray varies from 10(3)-10(5) degreesC s(-1) in contrast to a slow cooling rate of 1-10 degreesC s(-1) of the spray deposit. The spray enthalpy on the deposition surface increases linearly with the melt superheat. In contrast, the atomization gas pressure does not have a significant influence on the enthalpy of the spray in this process. The cooling rate of the deposits predicted from the model compares well with those obtained by the measurements.