Melting and resolidification of a substrate in contact with a molten metal: Operational maps

The melting and resolidification of the substrate or of previously deposited layers may play an important role in many processes such as thermal spray coating, microcasting, spray deposition and high-temperature casting. A good understanding of this phenomenon would help us to achieve better bonding between deposited layers in some cases or to avoid damage to the substrate in others. In the present work, these processes are looked at as the melting and resolidification of a substrate in contact with a layer of molten metal which may also solidify. Both the solidification of the deposited layer and the melting and then resolidification of the substrate or previous layer are calculated using nonequilibrium phase change kinetics conditions at the solid-liquid interfaces and an implicit finite difference method with interface tracking. A nondimensional analysis of the controlling parameters under various conditions was conducted, and allowed us to generate nondimensional operational maps that can tell us whether there will be substrate melting or not. If there is, other nondimensional maps were generated to quantify the maximum achievable melting depth for various process conditions. Some results on the interface velocity during substrate melting and resolidification for various process conditions and for variations in interfacial heat transfer coefficient with time are also presented.