基于阵列电极的破损环氧涂层失效演变行为研究

Study on Failure Evolution Behavior of Damaged Epoxy Coating Based on Array Electrode

涂层保护是金属腐蚀防护的关键方法之一。但是对于破损涂层来说,由于涂层/金属界面的封闭性,腐蚀性介质在涂层/金属界面扩散引起的涂层失效一直是各国学者争相研究的热点。因此采用阵列电极测试方法,结合电化学测试方法,建立了腐蚀性介质在涂层/金属界面上扩散引起的涂层失效过程。结果表明:涂层失效过程分为两个阶段:随着腐蚀性介质在涂层/金属界面上的扩散,体系的阳极区不断增大,涂层覆盖区域和未覆盖区域的电位差和电流密度差均减小,此时电化学阻抗特征表现为扩散阻抗,形成了界面为阳极、涂层未覆盖区为阴极的氧浓差电池;随着实验的进行,在氧浓差腐蚀的作用下,涂层完全失效,体系电位分布和电流密度分布与涂层无关。

Coating protection is one of the key methods for metal corrosion protection. However, for the damaged coating, due to the sealing property of the coating/metal interface, the coating failure caused by the diffusion of corrosive media in the coating/metal interface has always been a hot topic for scholars all over the world. Therefore, in this paper, the coating failure process caused by the diffusion of corrosive media on the coating/metal interface was established by using the array electrode test method combined with the electrochemical test method. The results showed that the process of coating failure was divided into two stages. With the diffusion of corrosive media on the coating/metal interface, the anode area of the system increased continuously, and the potential difference and current density difference between the coated area and the uncoated area decreased. At this time, the electrochemical impedance was characterized as diffusion impedance, and the oxygen concentration difference cell with anode as interface and cathode as uncoated area was formed. As the experiment went on, the coating completely failed under the action of oxygen concentration corrosion, and the potential distribution and current density distribution of the system were independent of the coating.