The impact of plasma-sprayed molybdenum particles on glass surfaces held at 25 and 400°C was photographed. A two-color pyrometer was used to collect thermal radiation from the particles to follow their temperature evolution and to calculate the splat cooling rate. Significant fragmentation of the splat on the surface at 25°C was observed. A 3D model of droplet impact and solidification was used to estimate the thermal contact resistances between the splat and glass. It was found that the thermal contact resistance was approximately two orders of magnitude smaller on the surface at 400°C, indicating faster solidification, which reduced splashing. The larger thermal contact resistance between the non-heated glass and splat was attributed to the presence of a gas barrier at the surface.

A numerical model is developed to study the effects of the contact resistance, droplet impacting droplet temperature, and substrate temperature on the droplet solidification rate and temperature of the droplet under the condition when the substrate can melt and re-solidify. Two-dimensional simulations show that the interface velocity is small in the area of poor contact with an irregular solidification interface shape. During the impact of Molybdenum on a steel substrate, Mo solidifies while the steel substrate melts.