Anti-corrosion Performance of LY12 Al Alloy Reinforced by Anodic Oxidization and Silanization

Anodic oxidation coatings were made on LY12 aluminum alloys by anodic oxidation in sulfurix acid. Then, γ-glycidoxypropyltrimethoxysilane (γ-GPTMS)/tetraethylorthosilicate (TEOS) hybrid films were prepared on the coatings by sol-gel method. The results of polarization curve and electrochemical impedance spectroscopy (EIS) measurements indicated that the passive current density of the aluminum alloy electrode with anodic oxidized films increased with the increase of immersion time. However, the passive current density was about 2 orders of magnitude smaller than that of aluminum substrate. After sealed by silane hybrid sol, the anti-corrosion performance of anodic oxidized films increased obviously, the passive current densities of anodic polarization of the aluminum alloy electrode with anodic oxidized films still maintained at 10-5 A/cm2 and the low frequency impedance values of the electrode were about 106 Ω after immersed for 822 h. The scanning electron microscopy (SEM) showed that the anodic oxidation coatings presented porous morphology, which is favorable for increasing the adhesion of silane hybrid films to metal substrate and reinforcing the corrosion resistance of anodic oxidized aluminum alloy electrode obviously.