Failure Mechanism Of Several Kinds Of Antifouling Coatings And Its Corrosion Resistance On5083Al Alloy

Aluminum alloy instead of pure aluminum in industry due to the strength of the aluminum alloy is higher than pure aluminum. Because of its low density, corrosion resistance, good performance, high specific strength, easy processing and forming, aluminum alloy is widely used in the Marine environment. The5083aluminum alloy is a kind of common Marine aluminum alloy which is used in manufacturing aluminum shell ships and fast vessel. When aluminum alloy ship is coated with antifouling coating which contains Cu2O, the antifouling coating will release Cu2+which will influence the corrosion resistance of aluminum alloy especially when the coating is damaged.The copper release and distribution in an aluminium alloy/anticorrosive primer/intermediate coating/antifouling coating system containing Cu2O were studied using XPS, FT-IR and EDS methods. The results show that during the immersion period in3.5%NaCl solution the pigment Cu2O in coating could react with chloride ions and oxygen in the solution to produce Cu2+, providing the antifouling effect. However, after long time of immersion, Cu2+could also penetrate into the intermediate coating and the anticorrosive primer, and the concentration of copper ions in each layer increases linearly with the immersion time.The potentiondynamic polarization, weight loss test and metallurgical microscope show that when the Cu2+concentration reaches the critical value the corrosion speed of aluminum alloy matrix under the coating system will be increased. If the coating system is damaged or its shielding property decreases, the release of Cu2+from antifouling coating would accelerate the corrosion of aluminum alloy matrix under anticorrosive primer/antifouling coating system. Compare antifouling coating contained Cu2O with acrylic resin on the corrosion resistant properties of5083aluminum alloy, the results show that the addition of Cu2O in antifouling coating will accelerate the corrosion of aluminum alloy.Research the corrosion resistant effect of antifouling coatings on5083aluminum alloy by the electrochemical method on the condition of the same anticorrosion primer and intermediate paint. Through the equivalent circuit simulate the failure process of the coating during immersion, and the coating for artificial damage simulation coating effect on the corrosion resistance of5083aluminum alloy matrix in damaged condition. The results showed that the coating that does not contain cuprous oxide has a good protective effect, even when the coating is damaged, it can still protect the aluminum alloy matrix in a long time.Compare Cu2O, CuSCN contained antifouling coating and foul release coating on the corrosion resistant properties of5083aluminum alloy. Through the EIS test and equivalent circuit fitting, research the behavior of coatings during immersion. Study the influence of the corrosion resistant effect of antifouling coatings on5083aluminum alloy by dynamic potential scanning and EIS test on the artificial damaged coating. It shows that protective effect of the foul release coating is the best because of its non-toxic.Compare the corrosion resistance of SEA-EF99A and NAF2008A,725-B40-CF1and725-B40-EF1on the condition of the same anticorrosion primer and intermediate paint. SEA-EF99A, NAF2008A,725-B40-CF1and725-B40-EF1are all contained Cu2O. The electrochemical tests show that NAF2008A has better protect effect than SEA-EF99A, and725-B40-CF1and725-B40-EF1have no difference in protect performance.