Effect of Powder Morphology on Surface Topography and Compositional Homogeneity of Oxide Coatings Deposited by Atmospheric Plasma Spraying (APS)

Abstract. This study aimed to assess the 3D surface roughness and chemical composition of APS coatings deposited on steel substrates. Two coatings were examined: TiO₂ on 41Cr4 steel and a TiO₂+ZrO₂+Al₂O₃ mixture on 316L steel. Microscopic observations using a KEYENCE VHX-6000 with 3D topography analysis showed lower Sa and Sq values for the TiO₂ coating compared with the composite coating. EDS analysis confirmed the dominance of Ti and O in the TiO₂ coating, as well as a low content of Al and Zr at the surface of the composite coating. This effect was linked to the morphology of the powders and differences in the degree of particle melting. Cross-sectional EDS maps revealed local enrichments of Al and Zr as well as porosity and microcracks typical of the lamellar microstructure produced by APS.