摘要
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 。
Passivity and passive film breakdown of carbon steel in alkaline solutions containing H 2S under anodic polarization have been investigated by electrochemical impedance spectroscopy. The results indicated that at the same pH value, the passivity of carbon steel in alkaline solutions is promoted by the addition of H 2S. The Nyquist diagrams were composed of two capacitive loops at the initial stage of passivation, with increasing anodic polarization potential, the capacitive loop at high frequency disappeared, the carbon steel specimen got into the stage of passivation. At potentials higher than -690mV, HS might he adsorbed on the surface of electrodes through competition with OH . Furthermore, the passive film began to dissolve due to the formation of ferric sulfide patches and the decrease in pH in and round the passive film faults caused by the oxidation of HS adsorbed. When the potential reached -635mV, the passive film was entirely brokendown.
出处
《中国腐蚀与防护学报》
CAS
CSCD
2000年第1期8-14,共7页
Journal of Chinese Society For Corrosion and Protection
关键词
电化学阻抗
极化曲线
钝化
硫化氢
炼油
EIS
Potentiodynamic polarization
Passivity
Breakdown of film.
