Evaluation of anticorrosive and self-healing performances of TiO2-added cerium conversion coatings developed on 211Z aluminium alloy

Titanium dioxide (TiO2) sol was added to the cerium conversion coating (CeCC) for preparing the CeCC-TiO2 composite coating covered on the surface of 211Z aluminium alloy. The anticorrosive and self-healing performances of the composite coatings were further investigated. The result shows the increasing Eg of CeCC-TiO2 could improve the anticorrosive and anti-intergranular corrosion performances of 211Z aluminium alloy under NaCl solution. Because the composite coating with high Eg value can effectively suppress the anodic reactions, provide greater coating resistance, and bring more compact surface structure. The self-healing ability of CeCC could be improved by adding TiO2 sol and the Eg value of the CeCC-TiO2 composite coating with the best self-healing performance is 3.38 eV. The cause of it lies in that the coeffect of the dynamic inhibition of Ce3+ and the inert inhibition of Ce4+ influences the self-healing performance of the composite coatings.