物理化学学报 >> 2004, Vol. 20 >> Issue (01): 70-75.doi: 10.3866/PKU.WHXB20040115

研究简报 上一篇    下一篇

用CR传输线模型研究涂层/金属体系阻抗谱

孙秋霞;张鉴清;林昌健   

  1. 浙江大学化学系,杭州 310027; 中国科学院沈阳金属研究所金属腐蚀与防护国家重点实验室,沈阳 110015; 厦门大学固体表面物理化学国家重点实验室,厦门 361005
  • 收稿日期:2003-04-04 修回日期:2003-07-31 发布日期:2004-01-15
  • 通讯作者: 张鉴清 E-mail:zjq@publicl.zju.edu.cn

Interpretation of Electrochemical Impedance Spectroscopy in Coating/Metal System by CR Transmission Line Model

Sun Qiu-Xia;Zhang Jian-Qing;Lin Chang-Jian   

  1. Department of Chemistry, Zhejiang University, Hangzhou 310013; State Key Laboratory for Corrosion and Protection of Metal, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016; State Key Laboratory for Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005
  • Received:2003-04-04 Revised:2003-07-31 Published:2004-01-15
  • Contact: Zhang Jian-Qing E-mail:zjq@publicl.zju.edu.cn

摘要: 根据CR传输线模型和QR电路之间的关系,建立了拟合其初值的计算方法,借助Z-View软件,可求得各元件精确值.根据电容(Ci)和电阻(Ri)随特征频率(f*)的分布,推导了元件相对增量与恒相位角元件(Q)指数参数n的关系. 结果表明, 当n小于0.5时,Ci比Ri增加得更快,从新的角度说明了n的物理意义及其和界面脱层之间的关系.作为应用实例,拟合了不同特征的电化学阻抗谱,分析了有机涂层/金属腐蚀体系阻抗变化的具体过程,区分了点蚀和脱层因素对阻抗谱的影响,从高阻抗体系同时得到了与不同空隙率有关的涂层电容和电阻值,并根据涂层体系的不均匀特征探讨了模型结构的物理意义.

关键词: 电化学阻抗谱(EIS), 传输线, 物理意义, 有机涂层

Abstract: According to the relationship between CR transmission line model (CR circuit) and QR circuit,an approach to calculate the initial value for fitting the former was found. Then,accurate values of its all elements could be obtained by using Z-View software. Based on the distribution of capacitance (Ci) and resistance(Ri)vs characteristic frequency (f*),the function of the relative increment of its elements vs the CPE(constant phase element)-power n could be drawn out. It showed that Ci value increased more quickly than that of Ri when n < 0.5, so the physical meaning of n and its connection with the delamination at the coating/metal interface were interpreted from a new standpoint. As examples of application, the fit of several different types of electrochemical impedance spectroscopy, the inspection of the evolution of impedances in organic coating/metal system with time, discrimination of the effects of corrosion and delamination on the impedance,as well as the samultaneous estimation of capacitance and resistance of coating with various interspace from high impedance system were performed. Finally, the physical meaning of the CR circuit in organic coatings system was discussed for the heterogeneous characteristics of organic coating.

Key words: Electrochemical impedance spectroscopy (EIS), Transmission line,  Physical meaning, Organic coating