Electrochemical impedance and noise data for polymer coated steel exposed at remote marine test sites

Abstract

The degradation of 12 different polymer coating systems on steel exposed to natural (NS) and artificial (AS) seawater has been monitored using electrochemical impedance spectroscopy (EIS) and electrochemical noise analysis (ENA). The marine test sites were Port Hueneme, California and Key West, Florida. A new approach has been developed to obtain electrochemical impedance and noise data from the remote test sites via modem from the laboratory at USC. A multiplexer was used at the marine test sites to collect these data for the different coating systems subjected to the two electrochemical tests. Impedance data were collected once a week, while noise data were measured twice a week. Potential and current noise data were determined simultaneously which allowed evaluation of spectral noise plots in the frequency domain and determination of the spectral noise resistance R sn o which together with the noise resistance R n was used to evaluate coating damage. The experimental approach is described and representative data from exposure to NS and AS for 7 months are presented for six coating systems which had different primer, midcoat and/or topcoat formulations. The aim of this project was to determine the impact of microorganisms on degradation of the protective properties of polymer coatings on steel during exposure to NS.