In this paper, three types of protective silane films, Methyltrimethoxysilane (MTMS), Vinyltrimethoxysilane (VTMS), and Dodecyltrimethoxysilane (DTMS) were prepared on aluminum alloys LY12 by electrodeposition technique. The Reflection-Absorption Fourier Transform IR (FTRA-IR) measurements showed that, the silane films were successfully deposited through the chemical bonding between silane agents and Al alloys. electrochemical impedance spectroscopy (EIS) tests indicated that in comparison with those by conventional "dip-coating" method, silane films prepared at cathodic potentials exhibited obviously higher corrosion resistances. "Critical potential" was generally observed for each silane system. Silane films prepared at this potential performed the highest corrosion resistance. The scanning electron microscopy (SEM) images indicated a potential dependence of surface morphology of silane films. The highest compactness was obtained at the "critical potential". Due to the presence of long hydrophobic Dodecyl chain in bone structure, DTMS films displayed the best barrier properties.
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