Corrosion Protection Assessment of Barrier Properties of Several Zinc-Containing Coating Systems on Steel in Artificial Seawater

Abstract The present investigation assessed the corrosion protection performance of different Zn sacrificial coating system configurations during constant immersion in artificial seawater. Visual observations and electrochemical measurements (including electrochemical impedance spectroscopy, EIS) were made periodically throughout up to two years of exposure time. Open-circuit potentials (Eoc) and low-frequency impedance values were plotted vs. time to investigate the corrosion protection of the steel substrates provided by coating system components as a function of exposure time. Visual observations, Eoc's, and EIS as a function of immersion time provided complementary results. Impedance results were found to be useful in predicting coating failure as long as the exact corrosion process is well understood.