Effect of the Structural Scale of Plasma-Sprayed Alumina Coatings on Their Friction Coefficients

The objective of this study is to compare the tribological properties of alumina coatings with two different structural scales, a micrometer-sized one manufactured by atmospheric plasma spraying and a sub-micrometer-sized one manufactured by suspension plasma spraying. Coating architectures were analyzed and their friction coefficients in dry sliding mode measured. Sub-micrometer-sized structured coatings present a lower friction coefficient than micrometer ones, thanks to their higher cohesion and smaller characteristic structural feature sizes.