Effect of substrate preparation on flattening of plasma sprayed aluminium bronze powders

摘要

Plasma spray coatings are produced by introducing powder particles of the material into a plasma plume, which melts and forwards them to the substrate. The flattening process of these individual molten droplets is one of the most critical factors as the coating quality strongly depends on the deposition of individual particles. Powders of aluminium bronze, a fine (-53 + 11 mu m) and a coarse one (-125 + 45 mu m) were plasma sprayed onto stainless steel substrates (AISI 304L) under atmospheric condition with three different substrate temperatures (25, 165 and 270 deg C). Two different ranges of surface roughness R_a were used: mirror polished substrates with about 0.01-0.03 mu m and grit blasted substrates with about 1-89-2-43 mu m. A scanning electron microscopy equipped with energy dispersive spectrometry system and an electron probe microanalysis, were used in order to study the splat morphology and the chemical composition of the splats.