干湿交替频率对有机涂层失效过程的影响

目的研究干湿交替频率对有机涂层失效过程的影响。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,对比研究高频率干湿交替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。结果高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13、2、5d,而低频干湿交替环境下,涂层在浸泡初期、中期、末期所经历的时长分别为18、4、46 d。对比来看,高频率干湿交替显著缩短了浸泡后期的时长,加速涂层失效过程。此外,高频干湿交替使涂层起泡位置分布均匀,基底金属均匀腐蚀,这与低频干湿交替环境恰好相反。结论高频率干湿交替环境下,涂层失效较快,涂层剥离及基底金属腐蚀较均匀。

Effects of Wet-Dry Alternating Frequency on Deterioration Processes of Organic Coatings

Objective To study the effects of wet-dry alternating frequency on the deterioration processes of organic coatings. Methods Electrochemical impedance spectroscopy was used in combination with photos of coating and corrosion morphology, to comparatively study the organic coating failure process in the beginning, middle and later stages of immersion under the conditions of high-frequency and low-frequency alternation of wetting and drying. Results Under the condition of high-frequency alternation of wetting and drying, the durations of the coating in beginning, middle and later stages of immersion were 13 days, 2 days and 5 days respectively. While under the condition of low-frequency alternation of wetting and drying, the durations of the coating in beginning, middle and later stages of immersion were 18 days, 4 days and 46 days respectively. By contrast, the duration in later stage of immersion was significantly shortened and the coating failure process was accelerated. Besides, under the condition of high-frequency alternation of wetting and drying, the positions of coating blisters were evenly distributed and the base metal suffered from uniform corrosion, which was opposite to the condition of low-frequency alternation of wetting and drying. Conclusion Under the condition of high-frequency alternation of wetting and drying, the coating failure was faster, the coating blisters was more evenly distributed and the base metal had from uniform corrosion.