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通过极化曲线和交流阻抗谱 (EIS)测定 ,对低碳钢在碱性H2 S溶液中的钝化及钝化膜破裂过程进行了研究。结果表明 ,相同pH值下 ,除氧碱性溶液中加入H2 S,对碳钢的钝化具有一定的促进作用 ;在阳极极化下 ,钝化初期阻抗谱具有两个时间常数 ,表现出不完全钝化的特征 ;随极化电位的升高 ,钝化膜逐渐完整 ,阻抗呈单一容抗弧特征 ,容抗弧半径逐渐增大 ;当极化电位高于 - 690mV时 ,由于电极表面HS 同OH 的竞争吸附和放电作用 ,导致电极表面钝化膜发生酸性溶解 ,并生成硫化物斑点 ,极化电阻显著下降 ,当极化电位高于 - 635mV时 ,钝化膜发生破裂 ,电极表面有大量硫化物生成
Passivation curves and AC impedance spectroscopy (EIS) measurements were used to investigate the passivation of mild steel in alkaline H2S solution and the rupture of passivation film. The results show that addition of H2S to deoxygenated alkaline solution can promote the passivation of carbon steel under the same pH value. Under the anodic polarization, the initial impedance spectrum has two time constants, showing no Passivation film gradually complete, the impedance was single capacitive arc resistance characteristics, capacitive arc resistance radius gradually increased; when the polarization potential is higher than - 690mV, due to the electrode surface HS With the competitive adsorption and discharge of OH, the passive film on the surface of the electrode was acid dissolved and formed sulfide spots, the polarization resistance dropped significantly. When the polarization potential was higher than -635mV, the passivation film ruptured and the electrode surface had A large number of sulfide formation