Marine Atmospheric Corrosion Resistance of Painted Electroplated Steel Plates after Damage of Surface Coating and Plating

The micromorphology and element distribution of corrosion product near the scratch of painted electrogalvanized steel plate and electrogalvanized nickel alloy steel plate explored in the marine atmosphere for 2 a after damage of surface coating and plating by scratch. The marine atmospheric corrosion resistance of painted electroplated steel plates after damage of surface coating and plating was discussed, and compared with original electrogalvanized steel plate and electrogalvanized nickel alloy steel plate. The results show that the marine atmospheric corrosion resistance of original electrogalvanized nickel alloy steel plate was worse than that of electrogalvanized steel plate, which was related to cracks in electrogalvanized nickel alloy steel plate during electroplating. After painting, although cracks existed in the zinc nickel alloy plating, the corrosion width near scratch was less than that of electrogalvanized steel plate, indicating that the marine atmospheric corrosion resistance of plainted electrogalvanized nickel alloy steel plate after damage by scratch was better than that of electrogalvanized steel plate, which was related to the phosphate formed by phosphating treatment before painting plugging cracks, and the existence of coating making the corrosive medium reach the coating only through the scratch side and the coating defect, and the nickel in the coating playing an advantage of improving the thermodynamic stability.