Evaluation of Barrier Properties of Antifouling Coatings on Naval Steel

Abstract

The barrier properties of two antifouling coatings, namely a silicone foul-release coat and an epoxy self- polishing coat, were examined through accelerated and natural weathering methods. The accelerated aging included exposure of intact coatings for 1.5 month in a UV chamber and for 3 months in a salt spray cabinet. Moreover, scribed specimens were tested into the salt spray chamber for 2 months. Natural exposure included immersion of intact coatings for 4 months in the laboratory at room temperature and in 2.5m depth in Elefsis Gulf, correspondingly. Periodic evaluation of the intact coatings was made through electrochemical impedance spectroscopy, 60o gloss, colorimetry, König pendulum hardnessmeasurements and visual examination. Analysis of the experimental results revealed that the silicone foul-release coating exhibits superior performance than its epoxy self-polishing counterpart, since it provides better antifouling protection, satisfactory barrier properties in both intact and flawed conditions, while retaining the color and gloss during the whole testing period.