Effect of Substrate Surface Condition on Flattening Behavior of Thermal Sprayed Ceramic Particles

Abstract

In order to make a thermal spray process highly controllable, it is essential to clarify the dominating factors of the process. Especially, the flattening behavior of the individual sprayed particle, which is the fundamental unit of the coating formation, has to be investigated precisely. In this research, the effect of substrate surface condition after preheating on the flattening behavior of the thermal sprayed particles was investigated. The surface roughness of the substrate before and after the pre-heating was measured by atomic force microscope (AFM), and the relation between the roughness and the splat morphology was investigated. The results obtained in this research are summarized as follows:
(1) The surface roughness of each substrate material was increased by the preheating, and splashing seemed to be induced by the surface roughness.
(2) The microstructure on the bottom surface of the splat changed from porous to dense with an increase of the substrate temperature. From this fact, it is indicated that the adsorbent on the substrate surface seems to affect the splashing.