Preparation And Corrosion Resistance Of Modified Graphene Oxide/Epoxy Resin Composite Coatings

Graphene oxide（GO）has garnered attention in the realm of metal corrosion protection due to its expansive surface area,formidable mechanical strength,and commendable chemical stability.When GO is added to an anti-corrosive coating as a filler,the increase in dispersion is important for the corrosion resistance of the coatings.In this paper,GO is modified with Lysine and SiO₂,and microstructure and morphology change law are analyzed.The influence of the type and amount of the filler on the corrosion resistance of the coating has been studied,as well as the change law of the corrosion resistance under the conditions of pre-deformation and tensile stress.The results showed that GO was modified by Lysine at different reaction temperatures,and C-N vibration peaks appeared on f-GO.When the reaction temperature was 90℃,f-GO90 can obtain better results,the laminate spacing is 0.99nm,the ID/IG value reaches 2.48,and the laminate thickness of f-GO90 increases to3.767 nm,indicating that Lysine was successfully grafted to GO surface.If the temperature continues to rise,the intermolecular forces will strengthen and the clustering phenomenon will become severe.f-SiO₂ is used to further modify f-GO,so that the modified GO structure can be improved,and the proportion is 2:3（SG2:3）composite has the best effect,the lamellar spacing is 1.04 nm,the I_D/I_G value is 2.71,and the lamellar thickness of SG2:3 is increased to 4.919 nm.In this case,the epoxy group on the surface of f-SiO₂ and the amino group of f-GO are fully bonded to form a stable f-SiO₂/f-GO composite（SG）.The type of filler has a certain influence on the corrosion resistance of the coating.Electrochemical impedance analysis of WEP,GO/WEP,f-GO/WEP,and SG/WEP coatings showed that SG/WEP had the highest coating resistance after 10 days of Na Cl immersion.After 300 h of salt spray testing,there were fewer corrosion spots on the coating,a smaller area of corrosion expansion on the scratch,and the adhesion loss rate is 27%,which indicates that the SG/WEP composite coating has excellent corrosion resistance.The corrosion resistance of SG/WEP coating is the best when the additive amount of SG is 0.1%.The electrochemical impedance shows that the corrosion current density and corrosion rate of SG/WEP coating are smaller than those of other additive amounts.Salt spray test also showed better corrosion resistance and the lowest adhesion loss rate.The proper amount of SG composite material with good dispersion can plug the pores of the coating,increase its diffusion path,and prolonging the time of corrosive medium entering the substrate,thus improving the corrosion resistance of the coating.Based on the finite element analysis method,we simulated the safe service condition of the coating under pre-deformation and tensile stress.Coating damage did not occur and the coating was safe to use.As the pre-deformation increases,the corrosion resistance of the coating gradually decreases.When the load is 6.5 k N,the coating still has a certain corrosion resistance.As the tensile stress is increased,the coating samples forth and crack,which leads to a gradual decrease in the degree of matching between the coating and the substrate,eventually peeling off and further deterioration of the corrosion resistance of the coating.When the tensile stress was 220MPa,the coating still has certain corrosion resistance.