Impact, Deformation and Cooling Down of Atmospheric Induction Plasma Sprayed Ceramic Particles and Their Influence on Coating Properties

In the present work ceramic particles (Al₂O₃, YSZ) are sprayed onto steel substrates using a radio frequency inductively coupled atmospheric plasma spray process (IC APS). Because of the low plasma velocity and the large plasma volume large particles can be completely melted. The particles reach the substrate with low velocities (in the order of 10 m/s). So, a special kind of deformation can be observed. Some characteristic values of impact and deformation are also quite different from some other thermal spraying technologies. Of course, that has an strong influence on the coating properties. It is shown, that a high kinetic energy of impinging particles is not an essential assumption for a high bond strength and a low porosity of the coatings. IC Plasma sprayed particle splats are investigated and compared with DC and HVOF sprayed ones. The influence of the particle impact and deformation on the coating properties is demonstrated. It is shown, that in spite of the low particle velocities coatings can be sprayed by IC APS with comparable quality, but with quite different coating properties such as the crystalline structure.