The characterization of protective properties for some naval steel/polimeric coating/3% NaCl solution systems by EIS and visual assessment

Abstract

Electrochemical impedance measurements have been made in 3% NaCl solution on coated naval steel with alkyd, epoxies, chlorinated rubber and acrylic conventional paints as well as with epoxy-polyamide, ethyl-silicate or alkyd zinc rich paints. Electrochemical impedance measurements have made it possible to monitor the uptake of the surrounding aqueous electrolyte into the paint and simultaneously to determine the extent of paint breakdown. Based on corrosion potential and impedance measurements, together with the visual assessment using both the ASTM Standards 610/85 and 714/87, the different paints have been ranked in terms of the effectiveness of their anticorrosive properties in a chloride containing solution. A comparison of visual assessment, corrosion potential and impedance measurements data indicates that the electrochemical impedance technique is a powerful tool for the study of the coated steel behaviour exposed to aggressive aqueous media.