Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (11): 2941-2950.doi: 10.3866/PKU.WHXB20101102

• ELECTROCHEMISTRY • Previous Articles     Next Articles

Evaluation of Metal Corrosion under Defective Coatings by WBE and EIS Technique

ZHANG Wei1,2, WANG Jia1,3, LI Yu-Nan1, WANG Wei1   

  1. 1. College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266100, Shandong Province, P. R. China;
    2. Qingdao Marine Corrosion Institute, Central Research Institute for Steel and Iron, Qingdao 266071, Shandong Province, P. R. China;
    3. State Key Laboratory for Corrosion and Protection of Metals, Shenyang 110016, P. R. China
  • Received:2010-07-28 Revised:2010-08-19 Published:2010-10-29
  • Contact: WANG Jia E-mail:jwang@mail.ouc.edu.cn
  • Supported by:

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

Abstract:

We investigated the corrosion of steel under defective coatings in 3.5% (mass fraction) NaCl solution by the wire beamelectrode (WBE) and electrochemical impedance spectroscopy (EIS) technique. During the entire coating deterioration process, the EIS diagrams were dominated by the substrate corrosion process of the defect while the coatings and underlying electrochemical processes were“averaged”out. However, according to the current distribution maps plotted using the WBE, EIS responses of the anodic and cathodic regions of the defect and underlying coatings were detected. Initially, the high anodic and cathodic current densities were only monitored at the defect areas and then the cathodic sites spread out beneath the coatings around t2948he defect while the anodic sites remained on the defect. The substrate corrosion initiation and development mechanism of the defect and underlying coatings is discussed based on experimental results.

 

Key words: Electrochemical impedance spectroscopy, Wire beamelectrode, Organic coating

MSC2000: 

  • O646