Spallation of a substrate by thermal shock and thermal expansion differential during splat cooling

The relationship of spallation to the time dependent heat transfer of the splat and the substrate was studied. Video and synchronized acoustic measurements were conducted to record the substrate spallation. The fracture process and mechanisms were also evaluated. The thermal contact coefficient was analyzed by matching the measured temperature valued with results from a heat conduction model with phase change. The spall formation mechanism was quantified by analyzing the geometric configuration of the splats and spalls under varying conditions of droplet superheat, droplet size, and droplet or substrate material.