Abstract
Effect of substrate temperature and ambient pressure on a flattening behavior of thermal sprayed particle has been investigated systematically in our lab. It was recognized from the results that splat morphology of any sprayed material changed from a splash shape to a disk one with increase of substrate temperature or decrease of ambient pressure. The most interesting feature is that this morphological change is defined as transitional phenomenon. Instead of the actual thermal spraying, freely fallen experiment was conducted in this study to measure the in-situ temperature history inside of the splat to estimate what is happening in an impact of particle onto the substrate surface. Mirror polished SUS304 plate and Cu particle were used for both substrate and droplet material, respectively. It was found from the results obtained that droplet decided its flattening pattern just after the collision onto substrate surface and ring shaped initial solidification at bottom surface of the splat might give the possibility to arrest the splashing. The contact nature between particle and substrate, namely wettability, can be the domination for this transition phenomenon.
