Investigating the Failure Mechanisms for an Expoxy-Polyamide Coating in a Seawater Environment

Abstract

The results from the first twelve months of alternate seawater immersion for test panels are presented here. After preparation, the test panels were either kept clean or deliberately contaminated with a set amount of NaCl and then coated with varying thicknesses of epoxy-polyamide coating and left at open-circuit or cathodically protected with a Zn anode. Visible corrosion was observed on samples that received chloride contamination but no cathodic protection, but multiple kinetics processes were observed on all the test panels. Though the alternate immersion regimen is not completed, results indicate that, although water uptake by the coating is significant and that the barrier properties of the coating are degrading, anodic dissolution is not proceeding to an appreciable extent on the non-contaminated surfaces.