STP727: Evaluation of Electrochemical Techniques for Monitoring of Atmospheric Corrosion Phenomena

    Mansfeld, F
    Group manager, Rockwell International Science Center, Thousand Oaks, Calif.

    Pages: 23    Published: Jan 1981


    Abstract

    A review is presented of past and present efforts to use electrochemical techniques to evaluate basic phenomena of atmospheric corrosion, measure time of wetness, and perform corrosion-rate measurements in outdoor exposure. This is followed by a summary of recent work carried out in the author's laboratory. Time-of-wetness measurements have been carried out continuously over a three-year period at the same location using copper/steel and copper/zinc sensors. An analysis of the monthly distribution of relative humidity and corrosion rates determined with the same sensors has resulted in correlations between them. Weight-loss measurements under thin layers of electrolytes that are drying out at RH < 100 percent have shown that, in most cases, corrosion rates are much higher under these conditions than in bulk solutions. Electrochemical measurements carried out under identical conditions show the continuous increase of corrosion rates during the drying period. A comparison of corrosion rates determined by weight loss and electrochemical techniques under thin layers of electrolytes indicates that the electrochemical data underestimate the true corrosion rates. The determination of cell factors based on weight-loss data is one approach for using the electrochemical technique in a more quantitative manner.

    Keywords:

    time of wetness, corrosion monitors, thin layer studies, outdoor exposure, weight loss data, cell factor


    Paper ID: STP28035S

    Committee/Subcommittee: G01.11

    DOI: 10.1520/STP28035S


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