Electrodeposition of cerium (III)-modified bis-[triethoxysilypropyl]tetra-sulphide films on AA2024-T3 (aluminum alloy) for corrosion protection

The doping of rare earth salts, like Ce(III), has shown to enhance the corrosion performance of silane films due to their self-healing behaviors. In the present paper, the Ce(III)-doped bis-[triethoxysilypropyl]tetrasulphide (BTESPT) films with higher corrosion resistance were prepared by electro-assisted technique. The films were investigated using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), water contact angle measurements and Fourier transform reflection absorption IR (FTRA-IR). The results showed that both the cathodic deposition and cerium-doping can promote the formation of thicker and compacter silane films and enhance their protectiveness in the early stage of immersion in the corrosive media. However, it seems that the Ce(III)-doped BTESPT films prepared by electrodeposition lose their self-healing abilities after long-term immersion. The reason is still unclear, but might be attributed to the precipitation of Ce(III) oxides or hydroxides during the electrodeposition of doped silane films.