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 structured at two different scales, a micrometric one manufactured by atmospheric plasma spraying (APS) and a nanometric one manufactured by suspension plasma spraying (SPS). Coatings architectures were analyzed and their friction coefficient in dry sliding mode measured. Sub-micrometric-sized coatings present a lower friction coefficient compared to micrometric- sized one, thanks to their higher cohesion and smaller structural feature characteristic sizes.