A novel combination microelectrode was constructed based on an iridium pH microelectrode and an Ag/AgCl microelectrode, and was applied to simultaneously monitor the steel potential, pH and chloride ion concentration in a crevice simulating disbonding of pipeline coatings with cathodic protection (CP) applied or removed. The sensing characteristics and sensitivity of the microelectrode are described as well as the calibration procedures. A simulated crevice was formed between a pipeline steel surface and a polymethylmethacrylate plate. The results showed that in CP conditions, the evident potential gradient resulting from the IR potential drop was concentrated at the crevice opening. A protective local environment induced by CP under disbonded coatings was characterised by an increase in pH and removal of Cl(-). After CP is removed, the protective effects can persist for a period of time, depending on the diffusion of soluble species.


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    Title :

    Electrochemical measurements using combination microelectrode in crevice simulating disbonded of pipeline coatings under cathodic protection


    Additional title:

    Elektrochemische Messungen mit zwei kombinierten Mikroelektroden an simulierten Fehlstellen (Spalt) von Pipeline-Beschichtungen bei kathodischem Schutz


    Contributors:
    Yan, M.C. (author) / Wang, J.Q. (author) / Han, E.H. (author) / Ke, W. (author)


    Publication date :

    2007


    Size :

    8 Seiten, 9 Bilder, 36 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English