2024铝合金阳极氧化膜的结构和耐蚀性能

为促进2024铝合金的进一步应用,用动电位阳极极化和电化学阻抗方法研究了2024 Al合金阳极氧化膜的结构及其在3.5% NaCl水溶液中的耐蚀性.结果表明,经硫酸阳极氧化的2024 Al合金较未处理基体的腐蚀速度降低了2个数量级以上,表现出相当好的保护性能;用光学显微镜、扫描电镜和透射电镜对阳极氧化膜的形貌观察发现,氧化膜表面平整,孔隙分布均匀,每个孔隙周围多含6个孔隙,也有5和7个孔隙结构,其孔隙尺寸细小,大小在10～30 nm之间.

Microstructures and Anticorrosion Behavior of Anodic Oxidized Coating on Al Alloy

Anodic oxidation coating was prepared on 2024 Al alloy making use of anodic oxidation in sulfuric acid.The corrosion resistance of the resulting anodized 2024 Al in 3.5% NaCl aqueous solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy.The morphology and microstructure of the coating were analyzed using optical microscopy,scanning electron microscopy,and transmittance electron microscopy.Results showed that the anodized coating on the 2024 Al alloy surface had excellent anticorrosion behavior in the aqueous solution containing 3.5% NaCl,namely,the corrosion rate of the anodized 2024 Al was lower than that of the untreated matrix by more than 2 orders of magnitude.The anodized coating was smooth and contained uniformly distributed pores of a size about 10~30 nm.