Performance Change and Comparative Study of Anti-corrosive Coatings in Seawater Environment with Alternating Pressure

Three anti- corrosive coatings were tested in alternating pressure condition simulating deep sea environment and water absorption, adhesion, surface morphology, cathodic disbonding resistance and resistance to chloride ion of the coatings were studied. The research showed that alternating pressure enlarged the porosity of the coating, so chloride ion, water and oxygen were easier to permeate into the coating or the interface of the coating and base metal, degrading the resistances to cathodic disbonding and chloride ion leaching. From the perspective of the surface morphology of the coating, the diffusion and accumulation of the corrosive media in the coating could contribute to the precipitation of soluble substances which would diffuse to the surface of the coating, resulting in the cracking of the coating.