低频率干湿交替环境中有机涂层失效过程

目的 研究低频率干湿循环条件下的有机涂层失效过程。方法 应用电化学阻抗谱技术，结合浸泡过程中涂层表面以及基底金属的形貌变化，对比研究全浸环境和低频率干湿交替环境下，浸泡初期、浸泡中期、浸泡末期有机涂层的失效过程及特征。结果 低频率干湿交替环境下，涂层在浸泡初期、中期、末期所经历的时长分别为18、4、46天，较全浸环境来讲，显著缩短了浸泡中期的时长，同时也显著延长了浸泡末期的时长。两种环境下的涂层均发生明显的局部剥离，且基底金属也均有明显的局部腐蚀。结论 低频率干湿交替环境明显延长了涂层的失效过程，且此环境下基底金属出现了明显的局部腐蚀。

Deterioration Processes of Organic Coatings under the Low-frequency Alternation of Wetting and Drying Condition

Objective To study on the deterioration processes of organic coatings under the low-frequency alternation of wetting and drying condition. Methods Electrochemical impedance spectroscopy, combining with photos of coating and corrosion morphology was employed to comparatively study the organic coating failure process in the beginning, middle and late of immersion under full immersion and low-frequency alternation of wetting and drying condition. Results Under low-frequency alternation of wetting and drying condition, the durations of the coating in beginning, middle and late of immersion time were 18 days, 4 days and 46 days respectively. Compared with the coating in full immersion environment, the duration in the middle of immersion time was significantly shortened and the duration in the late of immersion time was significantly extended. The coating suffered from obviously local peeling and the base metal suffered from obviously local corrosion. Conclusion The deterioration processes of organic coating is decelerated under cyclic wet-dry condition and the underlying metal in this environment suffers from apparent local corrosion.