Heat transfer characterization of the solidification process resulting from a spray forming process

Spray forming is achieved by atomizing a liquid metal sheet with an inert gas to form molten droplets, which are then subsequently deposited onto a moving cold substrate. During spray deposition processes, the developing pre-form loses thermal energy through a combination of heat transfer processes. To investigate such issues, a heat transfer model was developed to simulate the pre-form growth. This investigation involves the simultaneous heat transfer in the growing solid and mushy/melt region. The deposition rate is assumed to be continuous rather than discrete. Thus, the heat transfer process describing the growth of the deposit layer is mathematically formulated employing a continuous flow assumption. The influence of the system's controllable parameters such as substrate temperature and velocity, mass deposition rate, the superheat of the impinging metal droplets and environment conditions in the spray chamber on the final deposit and solidification are presented. All the parameters are found to have significant impact on the deposit development.