Abstract
A transition in the flattening behavior of thermally sprayed metals has been observed in previous studies. It has been proposed that ultra-rapid cooled chill structure preferentially formed at the bottom part of the splat may play a role in the generation of disk-shaped metallic splats. The applicability of this hypothesis to other materials was verified experimentally for several ceramic oxides. To accomplish this, Al2O3, Y2O3, and YSZ particles were plasma sprayed onto stainless steel substrates and the fraction of disk-shaped splats was measured as a function of substrate temperature. Splat microstructure was also examined. Unique amorphous and chill structures were observed in the bottom portion of Al2O3 and Y2O3 splats, indicating that similar formation mechanisms may be at work. However, only a columnar microstructure was observed in the YSZ splats, which calls for additional study.