Preparation And Anticorrosion Property Of Self-healing Coatings

Metal corrosion is one of the most common phenomena in daily production and life. One of the most effective ways to prevent metal corrosion is to cover the metal surfaces with anti-corrosion coatings. However, the anti-corrosion coatings are affected by environmental factors in the process of using, engendering defects. Coating defects accelerates the coating detachment from the metal substrate, and that further increasing the corrosion of metals. Up to now, how to effectively prevent the metal corrosion by self-healing coating technology is still a cutting-edge research topic. In this paper, several new self-healing coatings were prepared and their corrosion resistance was investigated, which would be helpful in the development of self-healing coatings.Firstly, white powder was synthesized by hydrothermal method and SEM and XRD results revealed that the powder was consisted of zinc oxide hollow microspheres (ZHM) with centered diameter of6y m. Then, ZHM were loaded with benzotriazole (ZHM-BTA). FT-1R results confirmed that BTA was successfully encapsulated and thermogravimetric analysis (TA) results indicated that the weight ratio of BTA in ZHM-BTA was around45%. ZHM-BTA were then added to epoxy resin coating. Ptentiodynamic polarization and electrochemical impedance spectroscopy (EIS) results showed that ZHM-BTA can confer self-healing anticorrosion properties on the coating. Once coating flaws and corrosion occurs subsequently, BTA contained in the coating can be released and prevent the corrosion of copper substrate.Secondly, manganese oxide was synthesized. According to the results of SEM and XRD, the obtained manganese oxide is composed of cubic crystalline Mn2O3hollow microspheres with centered diameter of5μm. The BTA was encapsulatd into MHM through the negative pressure-impregnation method. FT-1R results revealed that benzotriazole was successfully loaded into Mn2O3hollow microspheres. The obatined MHM-BTA was then added into the epoxy resin to prepare the Epoxy-Mn2O3-BTA functional coating. After creating defects with area of4mm2, the infulences of MHM-BTA on copper corrosion at the coating defects were investigated. Electrochemical means, including potential-time curve, current-time curve, dynamic polarization curves and EIS, and corrosion morphology revealed that the MHM-BTA doped in the epoxy coating can catalyze copper matrix to transform into CU2O, thereby promoting the adsorption of BTA on the copper surface, preventing corrosion of copper coating defects. Finally, in order to improve the corrosion resistance of aluminum, the functional coating Epoxy-AAO-8-HQ was developed. Porous anodic aluminum oxide (AAO) was prepared on the surface of aluminum substrate. SEM revealed that pores dispersed equally and the pore diameter was around50nm. Negative pressure-impregnation method was applied to encapsulate8-HQ into the AAO. FT-IR results indicated that8-HQ was successfully loaded. Subsequently, the preprocessed aluminum was coated with epoxy. A defect with length of3mm was created and then the self-healing process of the system was investigated. Potential-time curve, EIS results show that, the encapsulated8-HQ in the AAO microporous would release into electrolyte when the coating is mechanical damaged, preventing the corrosion of exposed aluminum, which displays a self-healing effect.