Deformation of Alumina Droplets on Micro-Patterned Substrates Under Plasma Spraying Conditions

摘要

The deformation of plasma-sprayed alumina droplets of 35-55μm diameter d with an impact velocity of around 90 m/s has been investigated over various micro-patterned substrates with an arithmetic mean roughness of 0.5μm. On a line-and-space pattern, droplets exhibited elliptical splats extending in the direction perpendicular to the line, when the normalized pattern spacing λ (= xld) was 0.1-0.3, where x is the pattern spacing. The fingering of the splats was also caused by a concave pattern as well as by a convex pattern and the number of fingers significantly increased at λ = 0.2. In addition, holes suggesting air entrapment were observed off center in the bottom side of each splat by approximately 1.5 times the radius of the droplets, regardless of the pattern. These results suggest the importance of the surface design of substrate on the micrometer scale in plasma spraying.