阳极氧化和硅烷化增强LY12铝合金耐腐蚀性能

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

采用阳极氧化法在LY12铝合金表面获得了多孔阳极氧化膜,再采用溶胶-凝胶法在其表面制备了γ-环氧丙氧丙基三甲氧基硅烷(GPTMS)/正硅酸乙酯(TEOS)杂化膜。极化曲线与电化学阻抗谱(EIS)研究表明,铝合金阳极氧化膜的维钝电流密度随浸泡时间延长而逐渐增大,但至试验结束其维钝电流密度仍低于裸铝合金约2个数量级。铝合金阳极氧化膜经硅烷杂化溶胶封闭后,其耐蚀性得到显著提高,浸泡822h后,阳极维钝电流密度仍能保持在10^(-5)A/cm^2,低频阻抗值仍达到10~6Ω数量级。扫描电镜(SEM)观察表明,铝合金阳极氧化膜为多孔结构,利于增强硅烷杂化膜与金属基体间的结合性能,显著提高阳极氧化铝合金电极的耐蚀性能。

Anodic oxidation coatings were made on LY12 aluminum alloys by anodic oxidation in sulfurix acid. Then, γ-glycidoxypropyltrimethoxysilane （7 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/cm^2 and the low frequency impedance values of the electrode were about 10^6 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.