| Waterborne epoxy resin coatings have caused wide public concern in the field of metal corrosion and protection due to its advantages of strong adaptability,environmentally friendly,ture waterborne,good maneuverability,high adhesion and good corrosion resistance.However,it is regrettable that the water resistance of waterborne epoxy resin coating is poor in the application process.There are two reasons limits its application in the actual industrial production.On the one hand,solvent volatilization produced the shrinkage cavity,on the other hand,the curing process is prone to the formation of cracks or cracks and other problems.According to recent studies,adding nano-filler into the waterborne epoxy resin preparates the nano-based polymer composite coatings,which is an effective methods to enhance the corrosion resistance of waterborne epoxy resin coating.Hexagonal boron nitride(h-BN)is a kind of graphite-like two-dimensional nanomaterial with excellent mechanical strength,thermostability,chemical stability and electrical insulation.Because of its electrical insulation,it can avoid galvanic corrosion fundamentally when applied in the field of metal corrosion protection.Therefore,h-BN is regarded as a two-dimensional lamellar material that can replace graphene and its derivatives in the field of metal corrosion protection.However,h-BN is chemically inertness on its surface,which severely limits its application in basic research and practical production.Therefore,it is improtant to modify the surface of h-BN.In this paper,h-BN was modified with a special functional modifier.And the modified hBN is not only in the waterborne epoxy resin(WBE)substrate showed good dispersibility and compatibility,but also the results of electrochemical impedance spectroscopy(EIS)and salt spray test show that the modified h-BN/WBE on P110 steel composite coating has excellent and long-time corrosion protection property.This paper includes three aspects as follows:(1)The h-BN-GO composite material was prepared by modifying h-BN with lamellar structure and water-dispersible graphene oxide(GO)with as a dispersant,and the effect of lamellar structure as modification on the corrosion resistance of epoxy composite coating was studied.The results showed that the h-BN modified by GO has good dispersion and compatibility in waterborne epoxy resin,and the existence of GO with laminar structure can improve the barrier ability of nano-filler to corrosive medium,so as to enhance the corrosion resistance of the composite coatings.(2)The PEI-h-BN composite material and PEI-BNNS/WBE composite coating were prepared by modifying h-BN with PEI.The results show that the PEI can modified and dispered h-BN through the lewis acid base action,improving its dispersing stability in aqueous solution,but also the PEI surface contains rich amino group(-NH2),which can interact with waterborne epoxy resin,and thus enhanced the crosslinking density of waterborne epoxy resin,reducing the defects of coatings.The PEI-BNNS/WBE composite coating has long-term anti-corrosion protection property.(3)The h-BN was modified with tannic acid(TA)to improve its dispersion stability in aqueous solution,and then the h-BN-TA-Zn2+ composite was prepared by using TA as the intermediate to adsorb cationic corrosion inhibitor zinc ion(Zn2+).The results show that the hBN-TA-Zn2+/WBE composite coating has the ability of pH response when metal corrosion occurs,and can automatically release cationic sustaining-release agent Zn2+ to form a passivation film on the metal surface,achieving the self-repairing performance of the composite coating,and then preparing the waterborne epoxy composite coating with excellent anticorrosion performance. |
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