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

    Published: Jan 1993

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    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.


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

    Author Information:

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

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

    Committee/Subcommittee: G01.11

    DOI: 10.1520/STP18085S

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