基于电化学方法分析了不同氯离子浓度混凝土模拟液中镀锌高强钢丝钝化膜的脱钝机理.结果表明：随着测试的进行，镀锌高强钢丝阴极出现越来越剧烈的析氢反应，其腐蚀速率在5%~7%NaCl模拟液中达到峰值；随着氯离子浓度的提高，镀锌高强钢丝的容抗弧半径呈现出先缓慢减小再急剧降低的变化趋势；钢丝发生点蚀后，生成的腐蚀产物将覆盖钢丝表面，抑制氯离子进一步侵入；钢丝脱钝机理表现为钢丝表面钝化膜受氯离子侵蚀破坏，以ZnCl₂的形式扩散到钝化膜表面，与溶液中的OH^-结合生成ZnCl₂·4Zn（OH）₂·H₂O等腐蚀产物；引起钢丝锈蚀的临界NaCl质量分数为4%，超过此界限，将加速钢丝钝化膜的破裂，加快腐蚀的发生；根据不同氯离子浓度模拟液中镀锌高强钢丝阻抗特性建立的双时间常数等效电路模型（b）拟合数据与实测数据吻合较好.

Electrochemical methods were employed to analyze the depassivation mechanism of the passivation films on galvanized high-strength steel wires in simulated concrete solution with different chloride concentrations. The results indicate that， as the testing progresses， an increasingly severe hydrogen evolution reaction occurs at the cathode of galvanized high-strength steel wire with the corrosion rate reaching its peak in 5%-7% NaCl simulated concrete solution. With the increase in chloride concentration， the impedance spectrum radius of galvanized high-strength steel wires exhibits a trend of initial slow decrease followed by a sharp decline. After pitting corrosion occurs on the wire， the generated corrosion products cover the wire surface， inhibiting further ingress of chloride. The depassivation mechanism of the wire is characterized by the destruction of the passive film on the wire surface due to chloride erosion， with ZnCl₂ diffusing to the surface of the passive film and combining with OH^- in the solution to generate corrosion products such as ZnCl₂·4Zn（OH）₂·H₂O. The critical chloride concentration causing wire corrosion is 4%. Beyond this threshold， the rupture of the passivation film on the wire is accelerated， hastening the onset of corrosion. Based on the impedance characteristics of galvanized high-strength steel wires in simulated concrete solutions with different chloride concentrations， the impedance spectrum data fitted by the dual time-constant equivalent circuit model（b） match well with the experimental data.

TU375

国家自然科学基金资助项目（51408359，52278527，52478536）