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应用阵列电极(WBE)联合电化学阻抗谱(EIS)技术,研究了气/液界面水线处破损涂层在3.5%(质量分数)NaCl溶液中的水线区破损涂层剥离行为。对比涂层剥离过程的腐蚀电流密度和阻抗谱分布行为,探讨了破损涂层在水线区的剥离机制。结果表明,涂层破损区和固有缺陷区均能够加速附近涂层阴极剥离过程。水线区破损涂层剥离行为特征为,破损区和固有缺陷区附近涂层首先发生阴极剥离,进而向外部涂层/金属界面扩展。此外,研究发现,破损区位于水线上方和下方时,其推动阴极剥离能力不同,即,加速水线下方涂层剥离作用弱于水线上方区域,致使水线及水线上方涂层剥离速率明显大于水线下涂层剥离速率。其原因显然与阴极剥离区溶解氧含量有关,即富氧区阴极剥离扩展速率大于乏氧区阴极剥离速率。
The stripping behavior of water-damaged coating in 3.5% (mass fraction) NaCl solution was investigated by using WBE combined with electrochemical impedance spectroscopy (EIS). The corrosion current density and impedance spectrum distribution of coating stripping process were compared. The mechanism of stripping of damaged coating in waterline area was discussed. The results show that both the damaged coating area and the inherent defect area can accelerate the process of cathodic disbondment in the vicinity of the coating. The delamination behavior of the damaged coating in the waterline zone is characterized by first cathodic disbondment of the coating near the damaged area and the inherent defect area, which in turn spreads to the outer coating / metal interface. In addition, the study found that the damage zone is located above and below the water line, which promote the cathodic disbondment ability, that is accelerated below the waterline stripping below the waterline above the waterline and water line above the coating peel rate Significantly greater than the waterline coating peel rate. The reason is obviously related to the dissolved oxygen content in the cathodal exfoliation zone, that is, the cathodal exfoliation expansion rate in the oxygen-rich zone is larger than the cathodal exfoliation rate in the hypoxia zone.