非恒温电解液中AA5083Al-Mg合金阳极氧化膜的制备及其耐蚀性

采用硼酸-硫酸-草酸电解液在铝合金表面制备有序多孔层,研究阳极氧化过程中电流随时间的变化,分析界面反应并计算膜层的生长效率。采用扫描电子显微镜、交流阻抗和动电位极化曲线研究膜层的微结构及其在不同温度环境下的耐蚀性。结果表明：在氧化层界面双离子层浓度的增大有利于提高膜层的生长效率。所制备的阳极氧化膜厚度为8-9μm,孔径为10-14 nm,膜层的微观形貌受金属基体组织结构的影响较大。在沸水封闭后膜层为分层结构,表面呈细片状。氧化膜层封闭后能够明显降低试样的自腐蚀电流密度,且耐蚀性随着环境温度的升高而具有更好的稳定性。

Growth and corrosion behaviors of thin anodic alumina membrane on AA5083 Al-Mg alloy in incalescent medium

A self-ordered porous film was fabricated on aluminum alloy in a ternary boric-sulfuric-oxalic acid electrolyte system. By means of voltage–time response, the oxidation process as well as the growth efficiency was studied. Field emission scanning electron microscopy（FE-SEM） was adopted to reveal the morphological and microstructural features of as-fabricated oxide layers. The corrosion protection properties of the films were investigated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The results showed that increasing the concentration of the double ionic layer located at the oxide interface could accelerate the film growth rate. The anodic oxidative layer with thickness of 8-9 μm and pore diameter of 10-14 nm maintains the pattern and topography of workpieces, compared with the overall closed film with hierarchical structure. Both samples exhibited much lower corrosion current density after boil water sealing. Meanwhile, a superior stability could be achieved through raising the ambient temperature.