| Abstract: | In the present work, silane-based organic-inorganic hybrid films doped with rare earth salt (cerium nitrate) were prepared by sol-gel method using γ-glycidoxypropyltrimethoxysilane (γ-GPTMS) and tetraethoxysilane (TEOS) precursors on 2A12 aluminum alloys. The electrochemical tests (such as polarization curve and electrochemical impedance spectroscopy (EIS)) were preformed to investigate the preparing process of Ce-doped organic-inorganic hybrid films (including the concentration of cerium salt doped in films and curing temperature of coatings) and characterize the performances of corrosion protection of the coatings for 2A12 aluminum alloys. At the same time, the corrosion resistance of Ce-doped coatings was compared with non-doped silane-based hybrid films, chromate conversion coating and rare earth conversion coating. The results of polarization curve tests indicated that the polarization resistance value of Ce-doped silane-based hybrid films increased by more than one order of magnitude compared with that measured for non-doped coating, and much greater than those of chromate and rare earth conversion coatings. EIS measurements gave the results in good agreement with those obtained from polarization curves, suggesting that silane-based hybrid process present promising potentialities as alternative method of chromating by improving the preparing technology of these films. |
