Cl^-作用下2A12铝合金在大气环境中腐蚀初期的微区电化学行为

Local electrochemical behavior of 2A12 aluminium alloy in the initial stage of atmospheric corrosion under Cl^- conditions

用扫描开尔文探针(SKP)和局部电化学交流阻抗(LEIS)技术,研究了2A12铝合金在盐雾腐蚀实验早期阶段的腐蚀行为和电化学过程.结果表明,盐雾实验初期,铝合金表面出现点蚀坑,Cl-对铝合金腐蚀有显著的加速作用,随盐雾时间延长,点蚀扩展.扫描开尔文探针的测试结果显示,在盐雾腐蚀过程的初期,金属表面阴极区和阳极区不断发生变化,呈现局部腐蚀的特征.随着盐雾时间的延长,试样表面电位逐步正移,并出现明显的阴极区和阳极区.局部电化学交流阻抗的测试结果表明,试样表面的局部电化学阻抗随盐雾时间的延长而有所增加,但分布较为分散.这说明在腐蚀过程的初期,2A12铝合金表面不断生成腐蚀产物,对腐蚀反应产生阻碍作用.

Scanning Kelvin probe （SKP） and localized electrochemical impedance spectroscopy （LEIS） were employed to investigate the corrosion process and electrochemical behavior of 2A12 aluminium alloy during the initial corrosion period. It is shown that Cl- accelerates the atmospheric corrosion of 2A12 aluminum alloy and pitting expands with exposure time during the initial stage. SKP results indicated that anodic and cathodic areas on the surface changed constantly with distinct characters of localized corrosion in the initial corrosion period. When the corrosion process continued, the surface potential of 2A12 aluminium alloy moved positively, while the anodic and cathodic fields distinguished evidently from each other. LEIS results showed that the surface localized electrochemical impedance in the initial stage increased with time, but distributed dispersively. During the initial stage of the corrosion process, corrosion products formed on the surface of 2A12 aluminium alloy constantly, which could restrict the corrosion process.