Self-healing corrosion protective capability of polymer coatings for aluminum

Abstract

The self-healing corrosion protective properties of polymer coatings for aluminum were investigated. Zirconium phosphate conversion coating and polymer coating, which are various primer and top coatings with a thickness of 5 and 11 mm, were applied to the surface of pure aluminum, and after creating a defect by means of a knife-edge, a corrosion test was carried out in 0.5 mass% NaCl solution at 40°C. The polarization resistance of each coating was measured using electrochemical impedance method to evaluate the self-healing capability of coatings. The polarization resistance of scratched specimen coated polymer containing pigment increased with increasing time, resulting in high resistance. Thus, the selfhealing capability of the polymer coating was recognized. The healing film formed on the scratched surface contained carbon. Analyzing component eluted from the coating, diethyl phthalate was detected. Polarization measurement of aluminum substrate in corrosive solution with the organic compound was conducted, and it was confirmed that the organic compound has the inhibiting effect against corrosion. The results showed that the organic compound was related to the formation of healing film.