Microstructure and Sliding Wear Resistance of Plasma Sprayed Al2O3-Cr2O3-TiO2 Ternary Coatings from Blends of Single Oxides

Abstract

Al2O3, Cr2O3, and TiO2 are most commonly used oxide materials for thermal spray coating solutions. Each oxide shows unique properties comprising behavior in the spray process, hardness, corrosion, and wear resistance. In order to exploit the different advantages, binary compositions are often used, while ternary compositions are not studied yet. Atmospheric plasma spraying (APS) of ternary compositions in the Al2O3-Cr2O3-TiO2 system was studied using blends of plain powders with different ratios and identical spray parameters. Coatings from the plain oxides were studied for comparison. For these powder blends, different deposition rates were observed. The microstructure, roughness, porosity, hardness, and wear resistance were investigated. The formation of the splats from particles of each oxide occurs separately, without interaction between the particles. The exception are the chromium oxide splats, which contained some amounts of titanium. The predominant oxide present in each blend has a decisive influence on the properties of the coatings. While TiOx causes a low coating porosity, the wear resistance can be increased by adding Cr2O3.