THEORY OF CERAMIC SPLAT FORMATION UNDER PLASMA SPRAYING

A new theoretical solution for the prediction of the thickness and diameter of a metal oxide splat (Prandtl number Pr>l) under plasma spraying (Weber number We>100, Reynolds number Re>100) has been derived and experimentally tested. The theoretical approach developed is based on a two-stage description of the process of splat formation (ideal and consequent viscous spreading of a melt over solidifying layer). The preliminary results of comparison show a satisfactory agreement between predicted and measured thickness and diameter of splats without introducing any empirical constant. The results obtained are of specific interest for understanding the basic phenomena of plasma spraying the coatings from the powder materials characterized by high viscosity and low thermal conductivity of the melt.