| Spray deposition is an approach to manufacture net or near-net shape metallic materials. It 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. Significant technical progress over the past three decades has helped spray forming to mature into a manufacturing technique. However, the fundamentals of spray deposition remain to be established.;During spray deposition processes, the developing pre-form loses thermal energy through a combination of heat transfer processes. To investigate such issues, the growth of the deposit layer was mathematically formulated employing a continuous flow assumption, and a heat transfer model was developed to simulate the pre-form growth, both for pure metal and binary alloys. First it was assumed there was no relative motion in the deposited materials, and the heat transfer characterization in the solidification process resulting from the spray deposition process was fully investigated. Then by taking into account the convection phenomenon in the melt, together with the heat conduction in the substrate and deposit, a thorough model of the process was developed, and the relevant thermal, momentum, fluid and solidification phenomena were established.;An interface-tracking method was used to solve the governing equations, and a grid subdivision technique was adopted on the moving interface. The numerical results demonstrated that the thermal profile in the deposit is affected in a complex way by process parameters, such as substrate temperature, velocity, mass deposition rate, thermal state of the impinging droplets and the environment conditions in the spraying chamber etc. We believe that by optimizing the processing parameters, solidification conditions during deposition can be achieved to manufacture a desired deposit of uniform microstructure and minimum porosity.;A grid-independence check was also made to assure the accuracy of numerical schemes. |
