海水中重防腐涂层的失效行为及扩散系数的测定

摘要

采用电化学交流阻抗谱(EIS)技术对环氧富锌底漆/环氧云铁中间漆/氯化橡胶面漆重防腐涂层在海水中使用初期的失效过程进行了研究,同时采用电容法分析了失效过程中水分的吸收问题及水分的扩散系数.结果表明:涂层体系在海水中的失效过程分为两个阶段,浸泡前120h,涂层电阻从起始的2.284×109Ω· crn2以大约1.9×107Ω· h-1的速率迅速下降到1.029×107Ω·cm2,120h后则以较小的速率(8381Ω·h-1)下降.而涂层的吸水过程(lnCc-t1/2)可以分为两个阶段,线性增加阶段(0～30h)和30h后缓慢增加阶段,并根据第一阶段计算得到涂层中水分的扩散系数D为2.9076×10-9cm2·s-1.%The degradation process of heavy-duty coatings system composed of epoxy zinc rich primer, micaceous iron oxide intermediate, and chlorinated rubber top coatings in seawater was studied by the electrochemical impedance spectroscopy (EIS). The evolution of coatings capacitance was investigated to illuminate the water diffusion process and coefficient during coatings aging process. The results showed that the degradation process of the heavy-duty coatings in seawater could be described in the two typical stages. The coating resistance decreased linearly at a rate of 1. 9×10Ω·h-1 and 8381Ω· h-1 before and after 120h respectively. The lnCc-t1/2 curve for heavy-duty coatings indicated that the coating capacitance presented two typical stages as the immersion time increased, the coating capacitance increased rapidly in the beginning time of immersion (0-30h), and then tended to be a slow growth stage after 30h. According to the linear part of lnCc-t1/2 in the early immersion period, the water diffusion coefficient D was obtained and the value was 2. 9076×10-9cm2 · s-1.