Plasma spray: Study of the coating generation

A plasma sprayed coating is built up particle by particle, resulting in a coating with a layered structure that is highly anisotropic. The spray parameters affect certain factors of the coating, such as the size and distribution of porosity, oxide content, residual stresses, macro and microcracks, factors which have an important influence on the performance and eventual failure of the coating. Many works (modelling and measurements) have been devoted to the particles in flight and how these parameters are influenced by the plasma jets and particle injection macroscopic parameters. However, there is a shortage of published information on the way the particles spread upon impact and solidify on the substrate or the previously deposited layers and how these phenomena are connected to the deposit microstructure. This paper was concerned with expanding our knowledge in this field by concentrating on the following: modelling of deformation and solidification of a droplet on a substrate; measurement of the splat formation and cooling; experimental results and comparison with models.