Thermal stability of titania films prepared on titanium by micro-arc oxidation

Micro-arc oxidation (MAO) is an effective technique to improve the properties of titanium and its alloy by forming a ceramic film on the materials surface. In high-temperature industrial applications, the thermal stability of the films plays a critical role. In order to evaluate the high-temperature stability of titania films synthesized on titanium substrates by MAO, we performed annealing at different temperatures. The composition, structure, and surface morphology of the annealed MAO films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and surface texture tests. Vickers indentation and pin-on-disc testing were also employed to investigate the micro-hardness and wear resistance of the films, respectively. The thermal stability of the MAO titania coatings remain very good up to 800 °C. The effects of post-annealing on the properties of the MAO TiO2 films and the underlying mechanism are discussed.