中文摘要：

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。

英文摘要：

The coating degradation and metal corrosion beneath the coating around the water- line zone of an electrode in 3.5%NaCl solution were studied by means of wire beam electrode（WBE）technique. The results showed that at the beginning of the immersion, the distribution of cathode and anode area was mainly affected by the water penetration process of coatings. As the immersion time extended, the effect of water- line zone expanded, while the water- line zone acts as cathode,and the electrode bottom zone acts as anode. Due to the high concentrations of dissolved oxygen of water-line zone, the cathode reaction was strong leading to serious coating degradation and severecorrosion of base metal beneath the coating. The reduction reaction of the dissolved oxygen on the cathode should occur before the initiation of the dissolution reaction of the metal substrate of the electrode. Once a damage spot occurred on the coating, where soon became a strong and stable anode-like area. Then the cathode area developed around the damaged spot of the coating exhibiting degradation characteristics as that observed on the artificial defects made in coating. Around the water-line zone, the degradation process of the coating and the corrosion process of the metal beneath the coating were affected by the water penetration in combination with the water-line effect,which resulted in a corrosion behavior quite vary from that of the bare metal.