物理化学学报 >> 2010, Vol. 26 >> Issue (09): 2361-2368.doi: 10.3866/PKU.WHXB20100825

电化学 上一篇    下一篇

锈层下碳钢的腐蚀电化学行为特征

邹妍1, 王佳1,2, 郑莹莹1   

  1. 1. 中国海洋大学化学化工学院,山东 青岛 266100;
    2. 中国科学院金属研究所, 金属腐蚀与防护国家重点实验室, 沈阳 110016
  • 收稿日期:2010-02-21 修回日期:2010-03-29 发布日期:2010-09-02
  • 通讯作者: 王佳 E-mail:jwang@ouc.edu.cn
  • 基金资助:

    国家自然科学基金(50971118)资助项目

Electrochemical Corrosion Behaviors of Rusted Carbon Steel

ZOU Yan1, WANG Jia1,2, ZHENG Ying-Ying1   

  1. 1. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, Shandong Province,P. R. China;
    2. State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, P. R. China
  • Received:2010-02-21 Revised:2010-03-29 Published:2010-09-02
  • Contact: WANG Jia E-mail:jwang@ouc.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (50971118).

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摘要：

采用极化曲线、线性极化电阻(LPR)和电化学阻抗(EIS)研究了海水中带锈碳钢的电化学行为, 结果发现:长期浸泡的内锈层对电极过程有较大影响;短期浸泡, LPR 和EIS测定的极化电阻(Rp)逐渐增大;而长期浸泡, Rp却逐渐减小;随着浸泡时间的延长, Rp出现了先增大后减小的变化趋势. 将锈层逐层剥离后研究了碳钢的电化学行为, 并结合傅里叶变换红外(FTIR)光谱和横截面结构分析表明, 这主要是因为长期浸泡后, 内锈层中出现了具有较高电化学活性的β-FeOOH, 并且其含量随着浸泡时间的延长而逐渐增加. 当进行电化学测试时, 在对体系进行一定程度极化的过程中, β-FeOOH 参与了阴极还原反应, 使电极过程不再是简单的阳极金属溶解和阴极氧还原, 加快了阴极反应速度, 从而导致Rp逐渐减小.

关键词: 电化学行为, 锈层, 极化电阻, 阴极还原, 傅里叶变换红外光谱

Abstract:

Electrochemical methods including polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) were used to characterize and investigate the electrochemical behavior of rusted carbon steel immersed in seawater. Results indicate that the inner rust layer that forms on the surface of the carbon steel after long-term immersion greatly affects the electrode process. Polarization resistance (Rp), determined by LPR and EIS, increases during the initial immersion period. After long-term immersion, it decreases. Rp initially increases and then decreases gradually with immersion time. The electrochemical characteristics of the rusted carbon steel were studied by removing the outer and inner rust layers. The materials were analyzed by Fourier transform infrared (FTIR) spectroscopy and their cross-sectional morphologies were obtained to determine the cause. The results show that the β-FeOOH, which exists in the inner rust layer, has high electrochemical activity. Its content increases with the growth of the inner rust layer. In the electrochemical tests, even a small amount of polarization allows β-FeOOH to participate in the cathodic reduction reaction. Besides the anodic dissolution of iron and the cathodic reduction of oxygen, rust reduction is also possible. For this reason, the cathodic reaction rate is promoted and Rp decreases.

Key words: Electrochemical behavior, Rust layer, Polarization resistance, Cathodic reduction, Fourier transforminfrared spectroscopy