针对Alloy690在局部腐蚀过程中氯离子的自催化腐蚀作用，提出了利用Ag2SO4作为缓蚀剂防止氯离子对Alloy690的局部腐蚀。首先利用 Tafel 极化曲线和电化学阻抗谱，分析了将不同浓度的 Ag2SO4加入到0.005 mol·L-1的NaCl溶液对Alloy690的缓蚀效率和表面结构的影响；然后通过X射线光电子能谱（XPS）对样品表面钝化膜的组成进行了分析，并与电化学阻抗谱分析结果进行了对比。研究结果表明：在 Ag2SO4浓度较低时，它与氯离子形成络合物可有效降低腐蚀溶液中氯离子的活动性，并且这些络合物会覆盖在Alloy690表面，抑制了Alloy 690的阳极氧化过程，改变了电极表面双电层结构，有良好的缓蚀效果。%According to the self-catalytic effect of chloride ion in corrosion process, a new method based on Ag2SO4 as corrosion inhibitor was developed to reduce local corrosion. The corrosion inhibition effect of Ag2SO4 on Alloy690 was studied in 0.005 mol·L-1 NaCl solution by using Tafelpolarization curves, electrochemical impedance spectroscopy(EIS) and X-ray photoelectron spectroscopy(XPS). The corrosion current density was greatly decreased. This indicated that (AgCl2)- or (AgCl3)2- between silver ion and chloride ion were formed to decrease activity of chlorine ion in corrosion solution. The adsorption of the complex compound would change the double-layer structure from two layers to three layers, inhibiting the anodic oxidation process of Alloy690. With the increase of concentration of Ag2SO4, equilibrium potential would rise, and capacitance of the solid/liquid interface would decrease. Better inhibition effect than other cases could be achieved when the concentration of silver sulfate and sodium chloride ratio equaled to 0.2. Therefore, silver sulfate is a good corrosion inhibition for Alloy690 in chloride solution.
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