PARTICLES CREATING PLASMA-SPRAYED AL2O3-PERCENT-TIO2 COATING(1 3)

We studied types of powder particles and their distribution with respe ct to the centre of coating after plasma spraying at constant position of plasma gun and substrate. The coating formed by plasma spraying of Al2O3 + 13%TiO2 powder consists of different types of particles - def ormed particles (splats), partially deformed particles and undeformed particles. Distribution of the particles on the substrate surface is n ot homogeneous. Small, undeformed powder particles, with their maximum dimensions less than 5 mu m, are present in all studied coating areas . The basic assumption of particle deformation after impingement on th e substrate is particle melting in plasma torch. We can find essential ly more melted powder particles in case of injector angle alpha = 75 d egrees, comparing with the position alpha = 90 degrees. Angle alpha de termines the position of powder injector to the axis of plasma torch.