Mechanical and tribological behavior of sol-gel TiO2-CdO films measured at the microscale levels

In this work, we present a mechanical and tribological study at the microscale of sol-gel TiO2-CdO films, which are used in photocatalytic applications. The films were deposited as a good-quality polycrystalline material with majority of CdO or CdTiO3 phases depending on their Ti/Cd concentration ratios. Films with the majority of CdTiO3 phase presented the highest hardness and lowest plastic deformation during the indentation tests. The evolution of wear, friction coefficient, and roughness on the films was quantitatively studied by multiple-passes measurements on a depth-sensing instrumented indentation system. These measurements allowed us to observe the films' wear mechanisms and correlate them with their microstructure and mechanical properties. To compare the crystal structure, mechanical properties and tribological behavior of these films, we also analyzed sol-gel CdO and TiO2 films deposited under similar conditions.