Nanoporous titania interlayer as reservoir of corrosion inhibitors for coatings with self-healing ability

Active corrosion protection of AA2024-T3 alloy has been provided by an environmental-friendly, well adhering pre-treatment system consisting of an inhibitor-loaded titanium oxide porous layer and a sol–gel based thin hybrid film. A novel approach aimed at developing a nanoporous reservoir for storing of corrosion inhibitors on the metal/coating interface has been proposed. The nanostructured porous TiO2 interlayer was prepared on the aluminium alloy surface by controllable hydrolysis of titanium alkoxide in the presence of template agent. The morphology and the structure of the TiO2 film were characterized with TEM, EDS, SEM, and AFM techniques. Different ways of loading of the inhibitor in the pre-treatment coating were discussed. In contrast to direct embedding of the inhibitors into the sol–gel matrix, the use of the porous reservoir eliminates the negative effect of the inhibitor on the stability of the hybrid sol–gel matrix. TiO2/inhibitor/sol–gel systems show enhanced corrosion protection and self-healing ability confirmed by EIS and SVET measurements.