Preparation And Anticorrosion Properties Of Modified Silica-Graphene Oxide/Epoxy Resin Composite Coatings

Corrosion can damage metal substrates,resulting in huge economic losses.Organic coatings can effectively prevent metal corrosion.As one of organic coatings,epoxy resin（EP）has good adhesion to metal.It has strong rigidity and low cost,and is widely used in the field of metal protection.However,EP has high brittleness and poor toughness,which makes the coating easy to fail.In recent years,mesoporous silica（MSNs）has attracted more and more attention of researchers as functional fillers.It can not only provide a physical barrier,but also can be loaded with corrosion inhibitors,which can be released at the corrosion site when corrosion occurs.Reacts with the metal surface and forms a passivation layer that inhibits the migration of corrosion factors to the metal substrate and interrupts the corrosion process,thereby providing"self-healing"properties.In this paper,pH-sensitive MSNs nano-microspheres and graphene oxide（GO）are used as fillers to be composited with EP,and the excellent mechanical properties and extremely high impermeability of GO are used to delay the penetration of corrosive media in the coating;stimuli-responsive nanocontainers The organic combination with the anti-corrosion coating can prevent the self-leakage of the corrosion inhibitor from being degraded by ultraviolet light,and avoid affecting the curing of the coating,so that the coating can obtain the self-healing function and prolong the service life.The specific research contents of this paper are as follows:（1）Preparation and properties of pH-sensitive PVP-MSNs@GO.First,MSNs were prepared using a modified St（?）ber method.Next,using bromomethyldimethylchlorosilane coupling agent（C₃H₈Br Cl Si）,the surface of MSNs was grafted with polyvinylpyrrolidone（PVP）to obtain PVP-MSNs and GO and PVP-MSNs were grafted to obtain PVP-MSNs@GO.Finally,PVP-MSNs@GO/EP composite coatings were prepared by incorporating them into EP at different mass ratios.The analysis showed that PVP was successfully grafted on the surface of MSNs by coupling agent,and PVP-MSNs were successfully loaded on the surface of GO.PVP-MSNs were loaded with tannic acid（TA）as a container and the loading amount reached11.36 wt%.The characteristic curves of TA release from PVP-MSNs under different pH conditions were detected by UV absorption spectroscopy.The release curve shows that:when pH=4 and 7,the release amount of the corrosion inhibitor is 10.9%and 16.1%of that at pH=9,respectively.The results of routine testing of the coating show that the composite filler is uniformly dispersed in the EP matrix,which improves the impact resistance.Compared with the EP coating,the average friction coefficient of the composite coating decreased by 66.32%;after immersion in 3.5%Na Cl solution for 48h,|Z|_{0.01 Hz} increased by four orders of magnitude,E_corr increased by 886 m V,and I_corrdecreased by three orders of magnitude.（2）Preparation and properties of pH-sensitive CS/PMAA-MSNs@GO.Using a simple and controllable"in situ polymerization"method,chitosan/methacrylic acid（CS/PMAA）was coated on the surface of MSNs to obtain composite beads.The coupling agent KH560 was used to graft GO and composite beads on the surface of MSNs.At the same time,the composite fillers with different mass ratios（1～5%）were incorporated into EP.The results of coating performance testing showed that compared with the EP coating,the average friction coefficient was reduced by 89.49%;immersed in 3.5%Na Cl solution for 48 h,|Z|_{0.01 Hz} increases by five orders of magnitude,E_corrincreases by 979 m V,and Icorr decreases by five orders of magnitude.FT-IR microscope and SEM Mapping results showed that tannic acid could convert iron oxyhydroxide to form iron tannin,which interrupted the corrosion process and formed self-healing properties.