Evaluation of long-term corrosion durability and self-healing ability of scratched coating systems on carbon steel in a marine environment

• Published in: Chinese journal of oceanology and limnology Vol. 35; no. 5; pp. 1094 - 1107
• Main Author: 赵霞 陈长伟 徐玮辰 朱庆军 戈成岳 侯保荣
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01.09.2017; Springer Nature B.V
• Subjects: Additives; Carbon; Carbon steel; Carbon steels; Chemistry; Coatings; Corrosion; Corrosion prevention; Current distribution; Defects; Durability; Earth and Environmental Science; Earth Sciences; Electrochemistry; engineering; Evaluation; Fibers; Glass fibers; Localized corrosion; Marine biology; Marine environment; Oceanography; Primers (coatings); Protective coatings; Self healing materials; Sodium chloride; Steel; Surface properties; Thiourea; Thioureas; Toughness; 划伤; 海洋环境; 涂层系统; 碳钢表面; 耐久性; 自愈性; 评价; 防腐蚀保护; corrosion; scratched coating system; self-healing; carbon steel; long-term
• ISSN: 0254-4059; 2096-5508; 1993-5005; 2523-3521
• DOI: 10.1007/s00343-017-6132-3

Defects in protective-coating systems on steel surfaces are inevitable in practical engineering applications. A composite coating system, including a primer, middle coat and topcoat, were used to protect carbon steel from corrosion in a marine environment. Two environmental additives, glass fibers and thiourea, were applied in the middle coat to modify the coating system. The long-term corrosion durability and self-healing ability of the scratched coating system were evaluated by multiple methods. Results of the electrochemical technologies indicated that the coating system that contained 0.5 wt.% fibers and 0.5 wt.% thiourea presented good corrosion protection and self-healing for carbon steel when immersed in 3.5% NaCl for 120 d. Evolution of localized corrosion factors with time, as obtained from the current distribution showed that fibers combined with thiourea could inhibit the occurrence of local corrosion in scratched coating systems and retarded the corrosion development significantly. Surface characterization suggested that adequate thiourea could be absorbed tmiformly on fibers for a long time to play an important role in protecting the carbon steel. Finally, schematic models were established to demonstrate the action of fibers and thiourea on the exposed surface of the carbon steel and the scratched coating system in the entire deterioration process.