用电弧喷涂方法在钢表面制备铝涂层，研究其在3.5% NaCl溶液中的电化学腐蚀行为。采用电子探针技术（EPMA）分析研究浸泡30 d后涂层横截面的成分分布特征，发现腐蚀介质可沿孔隙或夹杂物向涂层内部渗入，且已有部分Cl-渗达涂层深处。动电位极化实验结果显示，原始铝涂层具有明显的钝化现象，这与胶冻状腐蚀产物Al(OH)3的附着力较强以及Al2O3膜的形成有关。电化学阻抗谱(EIS)测试结果表明，铝涂层在测试期内的EIS 图谱变化可分成4个阶段：孔蚀萌生阶段、孔内酸化析氢阶段、介质渗达钢基体后涂层作为牺牲阳极的阶段和孔蚀群急剧发展阶段。提出电极在腐蚀过程中的不同阻抗模型。
Aluminum was deposited on steel using arc spraying, and the corrosion electrochemical behavior of the coatings in 3.5% NaCl aqueous solution was investigated. The electron probe micro-analysis (EPMA) was used to examine composition profiles of the coating cross section after 30 day immersion. The results showed that the corrosion medium could penetrate into the coatings along the pores or inclusions, and chloride ions have penetrated into the depth of the coatings. The potentiodynamic polarization curves showed the passivation phenomenon of the original aluminum coating, which was related to the strong adhesion of jelly corrosion product Al(OH)3 and the existence of Al2O3 films. The corrosion failure process of aluminum coating was investigated by means of electrochemical impedance spectroscopy (EIS) measurements. On the basis of the impedance diagram changes during the testing, the process can be separated into four stages: initiation of cavitations, acidification and hydrogen evolution in the hole, coating as the sacrificial anode when the corrosion medium penetrates into steel substrate and rapid development of cavitation groups. Finally various models for the electrode in the corrosion process were proposed.
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