Alumina and yttria stabilized zirconia (YSZ) (8 wt.% Y2O3) were plasma sprayed on smooth (R-a similar to 0.1-0.4 mu m) substrates preheated to 300 degrees C in order to study the splat formation, This preheating temperature was chosen to obtain very regular disk shaped splats quite adherent to the substrate made either of stainless steel 304 L, plasma sprayed alumina, YSZ polished coatings or pyrex.