流动海水环境中人工破损有机涂层的劣化过程研究

目的研究流动海水环境中人工破损有机涂层的劣化过程。方法使用电化学阻抗谱(EIS)技术对比研究流动海水与静止海水环境中破损涂层的劣化行为,跟踪观察涂层宏观形貌演变。结果根据EIS响应特征,发现流动海水中的人工破损有机涂层劣化更快,且在浸泡后期流动海水中破损涂层没有形成扩散阻抗。根据涂层宏观形貌发展,发现静止海水中涂层仅围绕破损处出现了面积较小的锈点和鼓泡,而流动海水中涂层因劣化而产生的锈点和鼓泡面积更大且大量分布在整个涂层表面。结论当人工破损有机涂层在流动海水和静止海水环境的浸泡过程中,涂层劣化首先从人工破损处开始。破损处成为局部腐蚀反应主要的阳极区,破损处周围的区域和涂层内在缺陷处成为扩展腐蚀反应的阴极区。流动海水中涂层的腐蚀产物累积与脱落更加频繁,导致涂层劣化速度加快和基体金属腐蚀加剧。

Degradation Processes of Organic Coating with Artificial Defects in Flowing Seawater

Objective To study the degradation processes of organic coating with artificial defects in flowing seawater. Methods The degradation behaviors of organic coating with artificial defects in flowing seawater and static seawater were in-vestigated with electrochemical impedance spectroscopy (EIS) technology; and the evolutions of macroscopic morphology of the coatings was observed. Results According to the EIS response characteristics, the degradation of organic coating with artificial defects in flowing seawater was faster; and the diffusion impedance did not appear during the late immersion. According to evolutions of macroscopic morphology of the coatings, it was found that some small rust spots and bubbling appeared around the artificial defect for the coating immersed in static seawater; while more large-area rust spots and bubbling appeared on the whole surface of the organic coating immersed in flowing seawater. Conclusion During immersion of the organic coating in static seawater and flowing seawater, the degradation of the coating firstly happens around the artificial defect. The defect position of the coatings becomes the main anode region of local corrosion reactions, and the artificial defects and the inherent defects of the coatings becomes the cathode area of the extended corrosion reactions. Corrosion products at the artificial defects position accumulated and fell off more frequently in flowing seawater, which accelerates the degradation of coating and corrosions of matrix metal.