电化学方法研究环氧涂层/基体在3.5%NaCl溶液中的腐蚀行为

采用电化学方法研究了两种常用涂层-环氧沥青涂层和环氧铝粉涂层在3.5%NaCl溶液中的腐蚀行为.腐蚀电位-时间结果表明,两种涂层的自腐蚀电位都比基体的更正,都能起到屏蔽作用保护基体,浸泡中电位向负方向移动说明活化腐蚀过程在继续.电化学阻抗结果表明,腐蚀介质能够较快的渗入涂层到达界面,使涂层的屏蔽作用降低,生成的腐蚀产物可在一定程度上抑制腐蚀的发展.并提出了两种涂层的等效电路模型,对阻抗结果进行了拟合.表明在浸泡初期涂层电阻随浸泡时间延长迅速降低,随后趋于稳定.指出电化学方法能获得与涂层性能有关的定量数据,非常适合于研究涂层/基体的性能.

Study on Corrosion Behaviors of Epoxy Coatings/Substrate Immersed in 3.5 % NaCl Solution by Electrochemical Methods

Corrosion behaviors of two kinds of common used coatings- bituminous epoxy coating and epoxy aluminum coating immersed in 3.5 %NaCl solution were studied by means of electrochemical methods. It shows from the corrosion potential with immersion time that the free corrosion potentials of these coatings are more positive than that of Q235 steel substrate, indicating they both can protect steel from corrosion through shielding role. Increasingly active potentials indicate corrosion is on in the course of immersion. EIS shows that corrosion species can reach the coating and substrate interface quickly, causing the decrease of shielding role and to a certain degree corrosion products can inhibit the propagation of corrosion. The equivalent circuit models of these coatings during the course of immersion were put forward, and EIS results were fitted. Quantitative data concerning about coatings properties were obtained by electrochemical methods, which is very suitable to research the performance of organic coatings/substrate system.