Study On Preparation And Anticorrosive Performance Of Modified Montmorillonite/epoxy Resin Composite Coating

Solvent based epoxy coatings are widely used to protect steel in corrosive environment due to their good metal adhesion,chemical resistance and easy processing.However,the epoxy coating itself has the problem of poor compactness,which needs further improvement to improve the long-term anti-corrosion effect.In this paper,silane coupling agent（APTES）,8-hydroxyquinoline and graphene oxide were used to modify montmorillonite,the modified montmorillonite was added to the epoxy coating to enhance its densification,and then the anticorrosive property of the composite coating was improved,the change of the interlayer spacing and grafting degree of the composite were studied by means of X-ray diffraction（XRD）and fourier transform infrared（FTIR）.The agglomeration of the composite was observed by SEM.The effects of the composites on the hydrophobicity,surface roughness and corrosion resistance of the epoxy coating were investigated by water contact angle,AFM and EIS.The specific research contents are as follows:（1）Montmorillonite composites modified by silane coupling agent were successfully prepared by in-situ intercalation polymerization,the preparation process of the powder was optimized and added into the epoxy coating,the structure,morphology,hydrophobicity and corrosion resistance of the composite coating were studied.The results show that the spacing of montmorillonite layer increases from 1.27nm to 2.01 nm before and after modification,compared with the pure epoxy coating（the contact angle is 74°and the surface roughness R_S is 45.5 nm）,the maximum contact angle of montmorillonite composite epoxy resin is 98°and the surface roughness R_S is less than 22 nm.When the mass ratio of coupling agent to montmorillonite is 1:2,the composite coating has the best anti-corrosion effect.After soaking for 30 days,the capacitive arc of the coating is the largest,and the|Z|_0.01Hzvalue is still greater than 10^10.5Ω·cm².（2）Montmorillonite/8-hydroxyquinoline composites were prepared by cation exchange and active site adsorption on the modified montmorillonite prepared in（1）,the process conditions were optimized by changing single variables:reaction time,reaction temperature and p H,and it was added to the epoxy coating,the effects of structure,morphology,thermal stability and filler content（0.2%,0.5%and 1%）on the hydrophobicity and corrosion resistance of the coating were studied.The results show that the crystallinity,size uniformity and layered structure of the composite are improved with the successful loading of 8-HQ on montmorillonite.Compared with the epoxy coating,the maximum hydrophobic angle of the composite epoxy coating is 99°and the minimum surface roughness R_S is 3 nm,the composite coating with 0.5%and1%content still maintains a larger impedance modulus after 30 days of immersion,and the value of|z|_0.01Hz is not less than 10^10.5Ω·cm²,and MMT@8-HQ compared with the other,it has good anti-corrosion effect.（3）The modified montmorillonite and graphene oxide（GO）prepared in（1）were used as raw materials to prepare montmorillonite/graphene oxide composites by covalent bonding of amino and epoxy groups.The best mass ratio of the composite（modified montmorillonite/go）was explored and added into the epoxy coating,the effects of structure,morphology,thermal stability and filler content（0.2%,0.5%and1%）on the hydrophobicity and corrosion resistance of the coating were studied.The results show that the maximum layer spacing of the composite is 2.18 nm,forming a loose layer by layer stacking structure.The dispersion effect is significant,the defects increase（I_D/I_G value increases from 1.021 to 1.178）,the specific surface area（31.6863m²/g）and pore volume(0.0104 cm³·g^-1)of the composite increase.The maximum contact angle of the composite coating is 96°and the minimum surface roughness Rs is 1.6 nm,the composite coating with 0.2%filler（mass ratio of modified montmorillonite to go is 7:3）still has a large capacitive reactance radian after soaking for 30 days,and the|Z|_0.01Hz is about 10¹¹Ω·cm².