铝阳极氧化膜在中性NaCl溶液中的亚稳态点蚀研究

使用动电位极化法,电化学噪声和扫描电镜技术研究了工业纯铝L2经不同电流密度阳极氧化和不同方法封闭后于1mol/LNaCl中性溶液中的腐蚀行为.结果表明,阳极氧化能大大提高L2的耐蚀性,但当氧化膜较薄或氧化膜经长时间在溶液中浸泡后,试样表面仍能发生亚稳态点蚀,并在极化曲线上出现电流振荡和电位振荡.扫描电镜观察则表明,这些亚稳态点蚀孔径一般小于10μm,主要产生在膜中的金属间化合物周围.若氧化膜厚度增加或使用沸水和重铬酸盐封闭,均可有效地抑制亚稳态点蚀的发生.

Metastable Pitting of Aluminum Anodic Film in Neutral Sodium Chloride Solution

Potentiodynamic polarization,electrochemical noise and SEM were used to study the corrosion behavior of L2 aluminum anodic film in 1 mol/L NaCl solutions.The results showed that anodic oxidization of aluminum increases its corrosion resistance greatly.However metastable pits were also observed when the film was thin or was exposed to the solutions for a long time.These pits with a diameter less than 10μm often occurred around the metallic inclusions in film.