析氢对钢表面涂层缺陷破坏过程的交流阻抗谱特征

EIS CHARACTERISTICS FOR DAMAGE PROCESSES OF COATING DEFECTS UNDER EFFECT OF HYDROGEN EVOLUTION

研究了在过保护电位作用下钢表面析氢作用对改性沥青涂层缺陷的破坏;并根据析氢电流变化,将破坏过程分为三阶段,研究了每阶段表面阻抗谱特征.结果表明,当析氢电流明显增大,相应阻抗图出现双容抗弧时,缺陷周围开始形成微观剥离;在-1.20 V、-1.37 V和-3.07 V(均为CSE)电位作用下,双容抗弧出现时间分别为:55天未发现、8天和0.5天;对-3.07 V下、30天的涂层缺陷观察证实了宏观剥离行为的存在.

The damage processes of a kind of modified asphaltum coating with defects on steels were investigated by experiments. The damage processes could by divided into three steps based on the current- time curves. The EIS characteristics were determined for each step. It was found that the micro-peels around the coating defect may exist provided double capacitance arcs appeared in EIS graphics, and the current of hydrogen evolution was increased. The results show that the time for existence of double capaci- tance arcs were much longer than 55 days under an overpotential of - 1.20 V （CSE） and only 8 days and half day for overpotentials of - 1.38 V and -3.08 V （CSE） , respectively. The micro-peels were also observed on coating defects under conditions of -3.08V and 30 days.