Analysis of electrochemical noise data for polymer coated steel in the time and frequency domains

Electrochemical noise data were collected by remote control during exposure of two coating systems applied on steel to natural seawater. The experimental data were analyzed in the time and frequency domains. The noise resistance, R(n), was calculated as the ratio of the standard deviations of potential sigma{V(t)} and current noise sigma{l(t)} fluctuations. After fast Fourier transform of the experimental data into the frequency domain, spectral noise plots were obtained from which the spectral noise resistance, R(sn)(o), was determined. The spectral noise plots were compared to impedance spectra and certain limitations of the electrochemical noise analysis technique were noted for protective coatings at early stages of exposure. A unique relationship of R(n) with the protective properties of polymer coatings remains questionable.