Various parameters that can be obtained from impedance data such as the break-point frequency fb, the magnitude of the phase angle minimum ϕmin at high frequencies, and the frequency fmin of ϕmin are useful to estimate the degree of deterioration of organic coatings on metals. Data obtained earlier by Kendig and Mansfeld for polybutadiene on steel have been reinterpreted using this concept. The delamination function defined in this paper based on impedance data agrees very well with the degree of delamination determined visually according to ASTM D 610.

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