Properties of UV-irradiated TiO₂, ZrO₂, and TiO₂-ZrO₂ films as pore-sealing layers on micro-arc-oxidized aluminum alloys

In this paper, the UV-assisted sol–gel route was employed to fabricate the TiO₂ pore-sealing films on the micro-arc-oxidized (MAO) aluminum alloys (MAO/Al). As compared with the TiO₂ film derived from traditional sol–gel method, the UV-irradiated TiO₂ film showed a structure with less cracks, resulting in enhanced electrode potential, higher impedance, and lower corrosion current. Further, we investigated and compared the properties of the UV-treated amorphous oxides, including the TiO₂, ZrO₂, and TiO₂-ZrO₂ films on MAO/Al. It was found that their corrosion resistances were related to the metallic–oxygen–metallic (M–O–M) lattice in the films. The MAO/Al sealed with UV-irradiated ZrO₂ pore-sealing film showed higher corrosion resistance than the samples sealed with UV-irradiated TiO₂ film or TiO₂-ZrO₂ film, which was owing to the fact that a larger amount of M–O–M lattice formed in the UV-ZrO₂ film during the UV irradiation. [Figure not available: see fulltext.]