Study of Corrosion Initiation of a Steel Panel from a Defect in Coating Using Localized Electrochemical Impedance Spectroscopy (LEIS)

    Volume 4, Issue 10 (November 2007)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 9 November 2007

    Page Count: 13


    Wu, Xiaomei
    Coating Research Institute, Eastern Michigan University, Ypsilanti, MI

    Wang, Tie
    Ford Motor Company, Dearborn, MI

    Montalvo, Eva
    Coating Research Institute, Eastern Michigan University, Ypsilanti, MI

    Provder, Theodore
    Coating Research Institute, Eastern Michigan University, Ypsilanti, MI

    Handsy, Carl
    RDECOM-TARDEC, Warren, MI

    Shen, Weidian
    Coating Research Institute, Eastern Michigan University, Ypsilanti, MI

    (Received 15 June 2007; accepted 8 October 2007)

    Abstract

    Localized Electrochemical Impedance Spectroscopy (LEIS) was used to study corrosion initiation of a cold-rolled steel panel covered by electrodeposited coating (Ecoat). LEIS technique, developed from the conventional electrochemical impedance spectroscopy (EIS) that usually measures the impedance over an area in square centimetres, can measure the impedance of a sample over a much smaller area, which makes it a more appropriate technique for studying the early stage of corrosion initiated from small defects, such as pinholes and voids in the protective coatings. In the presented study, an isolated pinhole in the coating was found first, and then the sample was immersed in a salt solution. Initiation and development of corrosion from the pinhole was closely monitored. LEIS spectra measured in different stages showed interesting variations. The corresponding equivalent circuits were introduced to study the process, followed by brief explanation of the process. The study helped us better understand the mechanism of the corrosion initiation and its early development.


    Paper ID: JAI101303

    DOI: 10.1520/JAI101303

    ASTM International is a member of CrossRef.

    Author
    Title Study of Corrosion Initiation of a Steel Panel from a Defect in Coating Using Localized Electrochemical Impedance Spectroscopy (LEIS)
    Symposium Advances in Electrochemical Techniques for Corrosion Monitoring and Measurement, 2007-05-23
    Committee A01