Substrate Melting and Re-solidification During Impact of High-Melting Point Droplet Material

In this paper, impact, spreading, and solidification of molten droplet on a dissimilar substrate along with substrate melting and its re-solidification are investigated numerically. Volume of fluid surface tracking method coupled with the solidification model within a one-domain continuum formulation is used to model the transient flow during the droplet impact, its subsequent spreading, and solidification. Evolution of melting front in the substrate is modeled by solving the governing equations for solidification in the substrate, too. Simulations are performed for the impact of a heated droplet on a substrate. The model predicts substrate melting, which can give better insight of bonding between the coating material and substrate, where droplet and substrate are of different materials. It is observed that melting in the substrate in the present case starts soon after the impact of the heated droplet. The depth and the width of the melting front in the substrate increase with the time and after reaching a maximum they start to decrease because of start of re-solidification from the melted edge. In the central part of the splat droplet solidifies, while the substrate remains melted which can enhance the coating strength and its bonding with the substrate.