铝合金微弧氧化膜在高温盐水中的耐蚀性能研究

Corrosion Behavior of Microarc Oxidized Alumina Films in High Temperature NaCl Solution

研究5052铝合金微弧氧化膜在70℃/7%NaCl溶液中浸泡不同时间的开路电位和电化学阻抗谱变化,分析微弧氧化膜层的防腐机理。研究表明,高温腐蚀溶液可快速通过微弧氧化膜缺陷渗透到基体铝合金表面,从而引发基体金属腐蚀;但腐蚀产物在膜层缺陷内的沉积可阻塞腐蚀溶液向缺陷内部渗透,又使微弧氧化膜具有一定的自修复能力,膜层电阻经过初始阶段的急剧下降后,基本保持不变;对微弧氧化膜进行封闭处理可有效提升膜层的自修复能力。

The corrosion behaviors of microarc NaCl solutions with different time were studied electrochemical impedance spectroscopy （EIS） oxidized 5052 alumina immersed in 70 ℃/7% through the open circuit potential （OCP） and measurements. The results reveal that high temperature solution could permeate through microarc oxidation films and induce the corrosion of aluminum alloy substrate in the initial stage. After that, the corrosion products depositing in film defects could block the permeation of solution, which make microarc oxidation films exhibiting a self-sealing ability. And the film resistance keeps mostly unchangeable after initial rapidly decrease. Sealing treatment of microarc oxidation film could improve the self-sealing ability effectively.