Flattening Mechanism of Thermal Sprayed Particles

Flattening mechanism of the single particle thermally sprayed onto the flat substrate surface was investigated by using metallic particles and stainless steel substrates. As the flattening pattern of the particle is decided so quickly just after the collision onto the substrate surface, which is extremely earlier than the flattening period of the splat, pattern decision mechanism was verified. To perform this, bottom surface microstructure of the splat was systematically investigated and effect of initial rapid solidification on the flattening was verified. Additionally, temperature history inside of the freely fallen droplet was directry measured as a simulation of the thermal spraying. By summarizing the results obtained, it was inferred that a ring shaped initial rapid solidification at bottom surface of the splat may act as a trigger for the splashing. Moreover, as a good contact nature between splat and substrate is given at the higher substrate temperature or lower ambient pressure conditions, more effective cooling occurred in the splat, resulted in the formation of the disk shaped splat.