STP1188: Evaluation of High-Performance Protective Coatings by Electrochemical Impedance and Chronoamperometry

    Granata, RD
    Senior research scientist and research assistant, Lehigh University, Bethlehem, PA

    Kovaleski, KJ
    Senior research scientist and research assistant, Lehigh University, Bethlehem, PA

    Pages: 13    Published: Jan 1993


    Abstract

    Coatings evaluation methodologies using electrochemical impedance spectroscopy (EIS) and chronoamperometry are described for high-performance corrosion protective coating systems. Three types of coating systems were studied: (1) fusion-bonded epoxy, (2) a marine-service epoxy, and (3) a polyimide used in electronics applications. The coating systems were monitored as a function of exposure to water, elevated temperature, and time. The data obtained were characterized by a high impedance at low frequency under ambient laboratory conditions that decreased with exposure time or temperature. The long-term, low-frequency decreases were irreversible; short-term, temperature-dependent decreases were reversible. Measurements are described which extended the limits of low-frequency measurements by use of a chronoamperometry technique. This low-current technique was a useful ancillary method for coating systems and enabled the estimation of low-frequency impedance and capacitance values not conveniently measurable by frequency response analyzers or fast-Fourier transform methods.

    Keywords:

    electrochemical impedance, polymer coatings, chronoamperometry, protective coatings, corrosion control


    Paper ID: STP18085S

    Committee/Subcommittee: G01.11

    DOI: 10.1520/STP18085S


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