Evaluation of the Corrosion Protection of Two Underwater Coating Systems in a Simulated Marine Environment

Ships' hulls are typically coated with coating systems which have both anticorrosive and antifouling purposes, and consist of a primer, a tie coat, and an antifouling coat. Within this study, the protective properties of two different anticorrosion-antifouling coating systems are evaluated in a humid and warm atmosphere, as well as in a simulated marine environment utilizing salt spray chamber testing and immersion tests with and without agitation. The tested coating systems differ in the type of antifouling coating, i.e., self-polishing antifouling based on copper, and a new fouling-release coating based on miscellaneous components. The corrosion performances of Stojanovi coatings in natural seawater are examined using open circuit potential measurements, electrochemical impedance spectroscopy, and pull-off tests. The antifouling properties are reviewed by visual examination, measurements of coating roughness before and after exposure to the testing solution, and after immersion in a solution containing Saccharomyces cerevisiae by measuring the optical density. The obtained results show better corrosion and antifouling properties of the coating system with a self-polishing antifouling top coat compared to the coating system with the foul-release top coat. A thicker biofilm was noticed on the plates immersed in seawater with agitation compared to stationary conditions for both antifouling coatings.