2017 Volume 66 Issue 7 Pages 238-245
Electrochemical method to evaluate the healing process of the film formed on steel part of cut edge of prepainted 55%Al-Zn steel sheet with inorganic anti-corrosion pigments and the dissolution property of hot dip galvanized Al-Zn part of cut edge was developed. Anti-corrosion properties of the film formed on steel part and hot dip galvanized Al-Zn part of the cut edge were separately evaluated by analyzing of polarization curves of specimens in 5%NaCl solution. The optimum potentials to compare the ability to inhibit the reduction reaction of hydrogen ion and oxygen by the film formed on steel part of cut edge and anodic dissolution of hot dip galvanized Al-Zn part of cut edge were determined, and then the healing process of the film could be quantitatively compared. Corrosion tests of cut edge of prepainted 55%Al-Zn steel sheet with various types of anti-corrosion pigments were conducted. The difference of the healing process by anti-corrosion pigments was analyzed using electrochemical measurement and EPMA, and it was revealed that the healing ability of vanadate acid anti-corrosion pigments is nearly equal to the conventional chromate pigments.
