Parametric study of metal droplet deposition and solidification process including contact resistance and undercooling effects

The effects of process parameters on metal droplet spreading and solidification are investigated numerically. The parameters include the impinging velocity, contact resistance between the droplet and substrate, and degree of undercooling associated with rapid phase change. A simplified model is adopted to describe the splat size evolution and energy equations for the liquid, solidified layer, and substrate are simultaneously solved to analyze heat transfer processes during solidification. The energy equations are coupled by boundary conditions such as contact resistance and undercooling in a regularized calculation domain formed by means of algebraic grid generation. The results reveal that impinging velocity and contact resistance have strong effects on both final splat size and solidification time. The effects of undercooling are not significant unless the nucleation temperature is low in relation to the initial liquid superheating.