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应用阵列电极(WBE)技术研究了浸泡在3.5%(质量分数)NaCl溶液中水线区大尺寸电极的涂层劣化和涂层下金属腐蚀发生发展过程。结果表明,浸泡起始时,电极表面阴极区和阳极区分布状态主要受渗水过程影响。随着浸泡时间延长,水线作用明显增强,水线处为阴极,电极底部为阳极,水线处溶解氧浓度高,阴极反应电流大,涂层劣化和涂层下的基体金属腐蚀严重。涂层下基体金属腐蚀溶解反应发生前,必先发生阴极溶解氧还原反应。涂层破损后该电极就成为稳定的阳极区域,阴极区围绕破损处展开,表现为人工缺陷涂层劣化特征。水线区的涂层劣化和涂层下金属腐蚀过程受到渗水过程和水线作用共同影响,与裸金属水线腐蚀行为差异较大。
The application of array electrode (WBE) technology to study the degradation of coatings and the development of metal corrosion under coating immersed in 3.5% (mass fraction) NaCl solution in waterline electrode. The results show that the distribution of cathodic and anodic regions on the electrode surface is mainly affected by seepage process at the start of soaking. With the prolongation of immersion time, the effect of waterline was obviously enhanced. The waterline was cathodic and the bottom of electrode was anode. The concentration of dissolved oxygen in waterline was high and the cathodic reaction current was large. The degradation of coating and the corrosion of matrix metal under the coating were serious. Cathode dissolved oxygen reduction reaction must occur before the coating under the substrate metal corrosion dissolution reaction occurs. After the coating is damaged, the electrode becomes a stable anode area, and the cathode area expands around the damaged area, showing the degraded features of the artificial defect coating. The deterioration of the coating in the waterline area and the corrosion process of the metal under the coating are affected by both the seepage process and the waterline, which is different from the bare metal waterline.