AM30合金表面氧化锆微弧氧化涂层的腐蚀破坏过程

Corrosion Process of A Zirconium Oxides Plasma Electrolytic Oxidation( PEO) Coating on AM30 Alloy

对一种镁合金表面氧化锆微弧氧化膜在3.5wt%氯化钠溶液中的腐蚀破坏过程进行了研究。采用扫描电镜对浸泡过程中膜层的形貌进行了观察,采用XPS和EDS分析了膜层经长时间浸泡后表面产物的组成以及膜层表面元素含量的变化;采用EIS研究了膜层在浸泡过程中的破坏过程。研究结果表明,膜层结构的破坏与腐蚀介质的渗透过程密切相关,在浸泡初期膜层外层的电阻值快速下降。在膜层外层的保护下,膜层内层的破坏相对滞后。此外,膜层中MgO的水解促进了氧化膜的失效。

This paper studied the deterioration process of a plasma electrolytic oxidation（PEO） coating containing zirconium oxides on AM30 magnesium alloy in 3.5wt% NaC1 solution. Morphologies of the coating after immersion for different time were observed using a scanning electron microscopy （SEM）. The chemical composition of the corrosion products formed on the coating after immersion tests and the variation of the content of elements on the coating were investigated using X-ray photoelectron spectroscopy （XPS） and energy dispersive X-ray spectroscope （EDS） , respec- tively. Electrochemical impedance spectroscopy（EIS） was used to study the corrosion process of the coating. The ex- perimental results suggest that the deterioration process of the coating is closely related to the diffusion process of cor- rosive media in the coating. The corrosion resistance of the coating＇ s outer layer dramatically decreases in the initial immersion stage. The deterioration of the inner layer is delayed with the protection effect of the outer layer. Additional- ly, the decomposition of MgO accelerates the failure process of the coating.