Effect of Particle-Substrate Materials Combinations on Morphology of Plasma Sprayed Splats

The structure and morphology of plasma sprayed splats are experimentally investigated using different droplet materials and substrate materials. Droplet materials include aluminum, copper, nickel and refractory metals such as molybdenum and tungsten, and substrate materials include aluminum, stainless steel, and molybdenum plates. The results show that the splashing occurs during the splatting of a completely molten droplet. Most splats formed by droplets molten completely are only central part of the ideal disk type ones, which are defined as the annulus-ringed disk-like splat. It is found that the morphology of such annulus-ringed disk-like splat is greatly influenced by the combination of droplet and substrate materials depending on whether substrate melting occurs. With the combinations of droplet and substrate materials which are of similar thermal properties the splashing of central area of splat tends to occur to present a honeycomb structure at the center of splat. When droplet impacting can cause melting of substrate annulus-ringed splat prefers to present a split type. The flattening ratio of an annulus-ringed disk splat is typically less than 2.