Research On Preparation And Properties Of Epoxy/nano-ZnO Composite Coatings

With the continuous development of science and technology, the requirement for material properties becomes higher and higher. Organic-inorganic nanocomposite materials not only combine the advantages of the two components, but also possess some novel properties because of their special structures. Therefore organic-inorganic nanocomposite materials become one of the most interesting research areas in recent years. Epoxy is a very important matrix material of composite coating. In this paper, nanometer zinc oxide was prepared through polymer-network gel, epoxy/nano-ZnO composite coatings were also prepared and characterized. Then the composite coatings were applied to the surface of Mg-Li alloy, the effects of the composite coatings on corrosion resistance of Mg-Li alloy were investigated.Firstly, the effects of materials proportion, system pH value, calcination temperature on nanometer zinc oxide(nano-ZnO) were analyzed and the optimal process conditions were determined, then nano-ZnO was successfully prepared. Nano-ZnO was modified by using silane coupling agent and modification mechanism was discussed. FT-IR spectrum showed that organic functional groups were successfully grafted on surface of nano-ZnO. Nano-ZnO was successfully modified in order to prepare the composite coatings.Secondly, epoxy/nano-ZnO composite coatings was successfully prepared and pretreatment process for Mg-Li alloy surface was also studied. Microstructure, thermal property and nano indenter property of composite coatings were studied through SEM, thermogravimetric analyzer, nano indenter tester, adhesive force tester. The results indicated that the composite coatings displayed two-phase structure, nano-ZnO particles were distributed homogeneously among the composite coatings. The thermal property and nano indenter property of composite coatings were better than those of epoxy coating.Thirdly, the effects of composite coatings on corrosion resistance of Mg-Li alloy were investigated by polarization curves and electrochemical impedance spectroscopy. The result showed that composite coatings greatly improved corrosion resistance of Mg-Li alloy. The mass fractions of nano-ZnO in the composite coatings have different effects on corrosion resistance of Mg-Li alloy. When the mass fraction of ZnO was 2% in composite coatings, the protective effect on Mg-Li alloy was optimum.