Distinct property effects on rapid solidification of a thin liquid layer on a substrate subject to self-consistent melting

摘要

Heat transfer of a molten splat in a thin layer rapidly solidified on a cold substrate subject to self-consistent melting and distinct thermal and physical properties has been numerically investigated. Micro-electro-mechanical systems, semiconductor technology, splat cooling, plasma or powder spray deposition, single and twin-roller melt spinning, strip and slab casting, melt extraction, etc. are usually characterized by rapid solidification of a thin liquid layer on a cold substrate. This work has proposed that the one-dimensional rapid freezing in the splat is governed by nonequilibrium kinetics at the solidification front while the melting in the substrate is determined from the traditional phase change condition. The results show that to delay the freezing of the splat and accelerate the melting of the substrate, an increase in the splat-to-substrate specific heat ratio and decreases in Stefan number, dimensionless solid conductivity of the substrate and substrate-to-splat density ratio are suggested. The freezing of the splat and melting of the substrate are delayed by increasing dimensionless initial temperature and decreasing dimensionless nucleation temperature of the splat. An early melting of the substrate while maintaining the same onset time for the freezing of the splat can be achieved by increasing the dimensionless kinetic coefficient and equilibrium melting temperature of the splat and decreasing the dimensionless equilibrium melting temperature of the substrate. The effects of the parameters on enthalpies and interface velocities in the splat and substrate are also presented.