Investigations on Particle Behavior at the Stagnation Zone for a Suspension Particle Jet in Plasma Spray Conditions

摘要

The suspension plasma spray process is now emerging at the industrial scale, and open questions remain regarding the formation of coatings through this process, especially regarding the relationship among particle impact, spreading and build-up into columns. Furthermore, concerns have been raised regarding the behavior of the suspension droplets in the plasma jet stagnation zone since it is a zone where plasma jet streamline directions and velocities are highly disrupted when the plasma jet impinges on a solid surface. In this study, the particle-laden jet streamlines were experimentally observed very closely to a flat surface using a particle image velocimetry technique. Submicron particles were collected in flight to determine which particles contributed to coating growth. The particle mean impact velocity against the surface was determined through image velocimetry and splat dimensions. The impact angles of the particles were also determined, and a correlation was identified with the growth angles of the columnar coating.