Effect of O2/Ar ratio on the microstructure and tribological properties of Y2O3 films by multi-arc ion plating

Multi-Arc Ion Plating (MAIP) technology was used to deposit yttrium oxide (Y2O3) ceramic thin films on Al2O3 ceramics and silicon wafers. The effects of varying the O-to-Ar gas flow ratio (Rc: 0.5, 1.0, 1.5, 2.0) and the annealing conditions on the phase composition, microstructure, mechanical properties, and tribological performance of the Y2O3 films were assessed. The films deposited at Rc values of 1.0 and 1.5 consisted of a single cubic phase structure. In contrast, films deposited at Rc values of 0.5 and 2.0 contained a small monoclinic phase and the cubic phase structure. The film deposited at an Rc value of 1.0 (oxygen flow rate of 200 sccm) exhibited a dense microstructure, the best mechanical properties (hardness of 14.2 +/- 0.191 GPa), and the lowest friction coefficient (0.142 +/- 0.003). Furthermore, the colour of the film changed from grey-black to white after annealing at 800 degrees C for 6 h. The oxygen vacancy of the thin film increased, with improving crystallinity, decreasing hardness and elastic modulus, and increasing grain size, friction coefficient and wear rate. The film exhibited the best tribological properties at 25 degrees C.