Controlloing principle for thermal spray processbased on flattening analysis of single splat ontosubstrate surface

In a flattening of the individual particles thermally sprayed onto the substrate surface, critical conditions were recognized both in the substrate temperature and ambient pressure. That is, the flattening behavior of a single splat changed transitionally from a distorted with splash to a lenticular without splash on that critical temperature and pressure range, respectively. A transition temperature Tt and a transition pressure Pt was defined and introduced by author respectively for those critical conditions. As a possible domination, the role of solidification, wetting and desorption of the adsorbates on the transition behavior were clarified from several points of views. Dynamic wetting was thought to be an intrinsic domination for this transition. From the fact that the dependence of Tt and Pt on the particle material has a similar tendency, it was indicated that both substrate temperature and ambient pressure have an equivalent effect on the transition. By selecting the moderate conditions in both factors based on Tt and Pt, the coating structure and any other properties of the coating may be controlled effectively.