| Metal corrosions will not only cause enormous economic loss and waste of resources,but also lead to accidents and harm people's lives.Traditional organic solvent-borne coatings will release a lot of volatile organic compounds(VOCs)during painting and use,seriously endangering the environment and human health.With the enhancement of environmental awareness among people,it has become an inevitable trend for the development of coating industry that environmentally friendly waterborne coatings replace traditional solvent-borne coatings.Compared with solvent-borne coatings,waterborne anticorrosive coatings have some shortcomings,such as the waterborne epoxy coating with large surface tension,poor adhesion between layers and insufficient closure,and need to be further modified.In this paper,the waterborne epoxy was used as binder,and two kinds of anticorrosive fillers were modified with water-soluble modifiers in the early stage.By comparison,the modified filler with better performance was obtained.Based on this,the corrosion resistance of waterborne epoxy coating was further improved by loading inhibitor with the modified anticorrosive filler as container.The specific studies are as follows:(1)Aluminum tripolyphosphate(ATP)was modified by water-soluble K-type carrageenan(KC)to improve the dispersibility of aluminum tripolyphosphate(ATP)in waterborne epoxy.Through electrochemical impedance spectroscopy(EIS)and salt spray test,it is concluded that the corrosion resistance of waterborne epoxy coating can be effectively improved by adding the modified filler(KC-ATP),and the effect is best when the addition amount is 1.0 wt.%.(2)Graphite oxide(GO)was modified by phytic acid(PA)to obtain the PA-GO anticorrosive filler.According to the analysis of infrared spectroscopy,Thermogravimetric analysis,X-ray diffraction and X-ray photoelectron spectroscopy,the surface of PA contained many hydrophilic groups and the ?-? interaction between graphite oxide layers was reduced by covalent bond modification,which greatly improved the dispersion of GO in waterborne epoxy.The results of EIS and salt spray test show that the addition of 1.0 wt.% PA-GO can effectively reduce the corrosion rate of coating and then improve the corrosion resistance of coating.(3)Grounded on the studies above,the PA-GO filler with good dispersibility and corrosion resistance was chosen to load corrosion inhibitor?benzotriazole(BTA)to obtain PA-GO/BTA functional filler.Subsequently,the PA-GO/BTA with different mass fractions was added in waterborne epoxy to prepare composite coatings,and the corrosion resistance of composite coatings was characterized by EIS and salt spray test.The results show that the addition of BTA can further improve the corrosion resistance of composite coating,especially in the early stage of immersion.The impedance value of composite coating with 1.0 wt.% PA-GO/BTA was 10~9 ??cm~2,which was three orders of magnitude higher than that of pure waterborne epoxy coating. |
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