Abstract
This work deals with the flattening of alumina molten particles, called droplets, on stainless steel substrates either smooth or blasted and preheated at different temperatures. The blasted surface roughness has been limited to Ra= 1.4 µm to image the flattening droplet. Besides flattening and splat cooling, the wettability of melted millimeter-sized alumina drops on the same substrates was measured. The transition temperature, Tt, has been shown to be different between smooth and rough surfaces. For a smooth surface, Tt, is 170°C, and at 200°C 100% of disk shaped splats are obtained. For the rough surface, Tt is close to 300°C with porous splats, becoming almost dense at 450°C. Close to alumina melting temperature, wettability does not vary with the substrate preoxidation, which may not be the case when the temperature is much over the melting one as in plasma spray conditions.
