MELTING AND RESOLIDIFICATION OF A SUBSTRATE IN CONTACT WITH A MOLTEN-METAL - OPERATIONAL MAPS

The melting and resolidification of the substrate or of previously dep osited layers may play an important role in many processes such as the rmal spray coating, microcasting, spray deposition and high-temperatur e casting. A good understanding of this phenomenon would help us to ac hieve better bonding between deposited layers in some cases or to avoi d damage to the substrate in others. In the present work, these proces ses are looked at as the melting and resolidification of a substrate i n contact with a layer of molten metal which may also solidify. Both t he solidification of the deposited layer and the melting and then reso lidification of the substrate or previous layer are calculated using n onequilibrium phase change kinetics conditions at the solid-liquid int erfaces and an implicit finite difference method with interface tracki ng. A nondimensional analysis of the controlling parameters under vari ous conditions was conducted, and allowed us to generate nondimensiona l operational maps that can tell us whether there will be substrate me lting or not. If there is, other nondimensional maps were generated to quantify the maximum achievable melting depth for various process con ditions. Some results on the interface velocity during substrate melti ng and resolidification for various process conditions and for variati ons in interfacial heat transfer coefficient with time are also presen ted. (C) 1998 Elsevier Science Ltd.