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Journal of Electrochemistry ›› 2021, Vol. 27 ›› Issue (6): 624-636.  doi: 10.13208/j.electrochem.210127

Special Issue: “腐蚀”专题文章

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Effect of Aluminum Alloy Surface Modification on Adhesion of the Modified Polyurethane Coating and Its Corrosion Protective Performance

Xian-Yin Kuang1, Shao-Qiang Jin1, Yan-Hui Cao1, Yan-Mei Zhang1, Shi-Gang Dong2, Long-Hui Zhu3, Li-Wen Lin1,4, Chang-Jian Lin1,*()   

  1. 1. State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen 361005, Fujian, China
    2. College of Energy, Xiamen University, Xiamen 361005, Fujian, China
    3. Shenzhen Feiyang Protech Gorp. Ltd, Shenzhen 518101, China
    4. Xiamen Xingang Anticorrosion Technology Co. Ltd, Xiamen 361021, Fujian, China
  • Received:2021-02-01 Revised:2021-03-04 Online:2021-12-28 Published:2021-03-27
  • Contact: Chang-Jian Lin E-mail:cjlin@xmu.edu.cn


The ordinary organic coatings on aluminum alloy usually encounter a problem of low adhesion to the substrate, which results in destruction and failure of the long-term protective performance of the anticorrosion systems. The surface modification of aluminum alloy is able to enhance the adhesion of organic coating on aluminum alloys, and to improve their protective performance. In this work, a combined surface modification of anodic oxidation and mussel adhesion protein/CeO2/3-aminopropyltriethoxysilane composite film (MCA) was developed on the aluminum alloy. The adhesion of modified polyurethane coated on the treated aluminum alloy and its corrosion protective performance were evaluated comprehensively by using contact angle, adhesion strength, electrochemical impedance spectroscopy (EIS), and scanning reference electrode technique (SRET). The measurements of EIS and SRET demonstrated that the MCA composite film on anodic oxidized Al possessed self-healing function and provided effective protection against early corrosion of aluminum alloy. The pull-off test showed that both anodic oxidation treatment and MCA composite film modification were able to increase the adhesion of modified polyurethane coating on aluminum alloy, and their combined action were supposed to remarkably enhance the adhesion strength up to 17.1 MPa. The reason for the improvement of adhesion was that the anodic oxidation treatment and MCA composite film modification could improve the surface roughness of aluminum alloy, and enhance the surface wettability and surface polarity, which is beneficent to enhance the bonding of the modified polyurethane coating to aluminum alloy surface. The EIS results showed that no any corrosion occurred for the modified polyurethane coating on the treated aluminum alloy during 65 d immersion in 3.5wt.% NaCl solution. The impedance value in low frequency range of the modified polyurethane coating always maintained at a high order of magnitude on the aluminum alloy treated by anodic oxidation and MCA composite film modification, showing an excellent protective performance of the coating system. The evaluation of Neutral Salt Spray (NSS) indicated that the modified polyurethane coating on the treated aluminum alloy owned superior corrosion protection performance, and the adhesion strength remained 13.1 MPa and no any corrosion was found at the scratch locations even after 1200 h of salt spray testing. It was concluded that combination of anodic oxidation and MCA composite film were capable of significantly improving the adhesion of modified polyurethane coating on aluminum alloy and providing long-term effective corrosion protection for aluminum alloy.

Key words: anodic oxidation, aluminum alloy, modified polyurethane, surface modification, corrosion protection, adhesion