Dodecyltrimethoxysilane(DTMS) films were prepared on LY12 aluminum alloys by electrochemical deposition.FTIR-RA tests showed
that the DTMS films were successfully deposited through the chemical bonding between silane agent and Al alloys,i.e.,by the formation of Si—O—Al bond.The corrosion inhibition of silane covered alloys was characterized by electrochemical impedance spectroscopy(EIS) measurements in NaCl solutions with a mass fraction of 3.5%. The results show that in comparison with those prepared at open-circuit potential(OCP),the DTMS films deposited at cathodic potentials displayed an enhancement in protectiveness.Furthermore,a "critical potential" were observed,at which the films prepared showed the highest barrier performance.Scanning electron microscopy(SEM) image indicated a potential dependence of surface morphology of silane films. The highest compactness was obtained at the "critical potential".The impedance models of DTMS covered Al alloys in corrosive solutions were also proposed in the present work.