基于电化学阻抗谱的Zn及Zn-Al涂层的自封闭机理研究

目前，热喷涂Zn—Al合金涂层已替代Zn及Al涂层，成为海洋环境下钢结构件腐蚀防护的首选方法。使用高速电弧喷涂和粉芯丝材技术制备了Zn—Al涂层，采用电化学阻抗谱法(EIS)，结合涂层腐蚀产物X-射线衍射(XRD)及涂层腐蚀后表面形貌分析，对比研究了Zn及Zn—Al涂层的耐蚀性，并探讨了涂层的自封闭机理。结果表明，活化溶解是Zn涂层腐蚀的主要机制，在腐蚀过程中Zn涂层表现出自封闭作用，但由于腐蚀产物是疏松的，其自封闭效果微弱；Zn—Al涂层表现出了更好的耐蚀性，涂层表现出一定的自封闭效果。

Study on Self-sealing Mechanism of Zn and Zn-Al Coating Based on Electrochemical Impedance Spectroscopy

Presently, thermal sprayed Zn-Al alloy coating has become the best way to protect steel structure in oceanic circumstance instead of Zn and Al coating. High velocity arc spraying (HVAS) and cored wires techniques were applied to produce Zn-Al anti-corrosion coating, and EIS (Electrochemical Impedance Spectroscopy) measurement in conjunction with the XRD results of corrosion products and SEM analysis of corrosion surface were used to comparatively investigate the corrosion properties of Zn and Zn-Al coatings, and to study the self-sealing mechanism. The results show that the active solution is the main corrosion mechanism of Zn coating. It exhibits self-sealing function in the corrosion process, but the self-sealing effect is weak because of the loose corrosion products. Zn-Al coating represents better corrosion resistance because of the better self-sealing effect, which begins from the solution of Zn in the coating surface.