Electrochemical impedance spectroscopy (EIS) was used to study the degradation process of epoxy residual rust paint in 3. 5% NaCl solution under wet-dry cyclic condition. The EIS results showed that similar to the situation in immersion environment, the degradation process of epoxy residual rust paint in wet-dry cyclic condition included three stages: fast decrease of impedance value, stable protection stage, and failure stage. However, compared with the complete immersion environment, under wet-dry cyclic conditions the coating impedance was lower by two orders of magnitude, the coating capacitance was higher by one order of magnitude, and the failure rate was obviously higher. The failure mechanism of the epoxy residual rust paint in wet-dry cyclic conditions was mainly attributed to the swelling and shrinking of the coating, which increased the coating porosity. In addition, wet-dry cycles also promoted the diffusion of oxygen to the metal/coating interface and the enrichment of chloride ions at the metal/coating interface, which accelerated corrosion of the substrate and degradation of the coating.%应用电化学阻抗谱(EIS)技术研究了浸泡在3.5％ NaCl溶液中的环氧带锈涂层在于湿交替条件下的劣化过程.结果表明,干湿交替环境下环氧带锈涂层的阻抗变化与全浸环境类似,表现为3个阶段:阻抗迅速降低阶段,缓慢降低阶段和最后的失效阶段,但干湿交替环境中涂层阻抗值比全浸环境要低两个数量级,涂层电容则约高一个数量级,涂层失效速率明显高于全浸泡环境下的失效速率.环氧带锈涂层在干湿交替环境下的失效原因,主要可归因于干湿交替循环使涂层发生溶胀与收缩,增加了涂层的孔隙率；此外,干湿交替状态也会促进氧向涂层/金属界面的渗透,从而加速基体金属的腐蚀并加快涂层的失效过程.
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