论文部分内容阅读
分别研究了裸LY12铝合金及涂覆环氧树脂涂层后合金在3.5%NaCl溶液中的电化学阻抗谱(EIS).结果表明,LY12铝合金在点蚀电位以下阻抗谱上出现两个容抗弧,高频段对应Cl-参与的成膜阻抗,低频段对应铝阳极溶解的电化学反应阻抗.合金发生点蚀后出现低频感抗弧.合金/电极在NaCl溶液中先发生涂层吸水,当水及O2抵达基体后建立起电化学反应界面,合金遭受腐蚀;受涂层阻挡的影响,腐蚀产物的扩散逐渐成为控制步骤;当扩散速度较慢的Cl-抵达涂层/金属界面后,与界面处聚集的腐蚀产物间发生化学反应,完成成膜过程,阻抗谱上出现盐膜的阻抗,而扩散阻抗消失.提出了不同浸泡失效阶段涂层电极体系的阻抗模型.
The electrochemical impedance spectroscopy (EIS) of bare LY12 aluminum alloy and epoxy resin coating in 3.5% NaCl solution were studied respectively. The results show that there are two capacitance spectra of LY12 aluminum alloy under the pitting potential Arc resistance and high frequency band correspond to the formation resistance of Cl-, and the low frequency band corresponds to the electrochemical reaction impedance of aluminum anode dissolution. The low frequency induction arc appears after pitting corrosion of the alloy. The alloy / When water and O2 arrive at the substrate, an electrochemical reaction interface is established and the alloy suffers from corrosion. Due to the barrier of the coating, the diffusion of corrosion products gradually becomes a control step. When the diffusion speed of Cl- reaches the coating / metal interface, And chemical reaction between the corrosion products accumulated at the interface, the film formation process is completed, the impedance of the salt film appears on the impedance spectrum, and the diffusion impedance disappears.The impedance model of the coating electrode system with different immersion failure stages is proposed.