Research On Anticorrosion Performance Of Graphene-based Composites/epoxy Coating

As a new type of two-dimensional material,graphene has the characteristics of high strength,high conductivity,layered structure and non-penetration of atoms.In recent years,it has attracted much attention in the field of corrosion prevention.When graphene is dispersed in coatings,its layered structure can extend the permeation path of corrosive media such as water and oxygen,thus improving the anticorrosion ability of the coating.However,due to the strong electrical conductivity of graphene,it is easy to form a corrosive micro battery after contact with metal,which may lead to the hidden danger of accelerated corrosion,which limits the application of graphene coatings.By combining non-conductive inorganic oxide with graphene,the latter can be shielded from electrical conductivity and anti-corrosion performance can be improved.In this project,two specific composite materials were prepared and their anti-corrosion performance in epoxy coating was studied.Firstly,we studied the corrosion resistance of graphene powder before and after modification of silane coupling agent in epoxy coating.The mechanical properties and the EIS tests of the coating showed that the preferred addition of graphene powder was 0.5wt%.Compared with KH550,Z6173,POTS three silane coupling agent modified graphene effect,it is concluded that the coupling agent Z6173 modification is better.After 30 days of immersion in 3.5wt%NaCl solution,the values of Z0.01 for 0.5wt%Z6173-G coatings was 4×108Ω·cm2,that is better than G and pure epoxy coatings.The SEM of the coating surface and cross section showed that the modification of coupling agent could improve the dispersion of graphene in the resin.Secondly,tetraethyl orthosilicate was used to hydrolyze and condense,and silicon dioxide was grown on the surface of graphene to prepare graphene/silica composites.The amount of tetraethyl orthosilicate,ammonia and the reaction time were discussed.The optimal synthesis conditions of the composite were found to be:50mg graphene,1.0ml tetraethyl orthosilicate,1.0ml ammonia solution and stirred for 24h at room temperature.SEM showed that the surface of graphene was uniformly loaded with silica;the TGA test showed that the mass ratio of graphene in the composite was about 31.2%.Modified the composite material with Z6173 and added it to the epoxy coating.The test showed that the optimal additive amount of the modified composite material was 1.5wt%,it’s anticorrosion performance is greatly improved compared with the graphene coating.The Z0.01 of the coating was 4.5×1010Ω·cm2 after 1 day of immersion and decreased to 6.4×109Ω·cm2 after 30 days of immersion.At the same time,using tetrabutyl titanate as the titanium source,titanium dioxide was grown on the surface of graphene by hydrolysis shrinkage method to prepare graphene/titanium dioxide composite materials.The amount of tetrabutyl titanate,ammonia and the reaction time were discussed.The optimal synthesis conditions of the composite were found to be:80mg graphene,0.3ml tetrabutyl titanate,0.5ml ammonia solution and stirred for 4h at 45℃.SEM showed that the surface of graphene was uniformly loaded with titanium dioxide;the TGA test showed that the mass ratio of graphene in the composite was about 57.3%.Modified the composite material with Z6173 and added it to the epoxy coating.The test showed that the optimal additive amount of the modified composite material was 1.0wt%and more lasting protection than graphene coatings.The Z0.01 of the coating was 8.2×1010Ω·cm2 after 1 day of immersion and decreased to 7.7×109Ω·cm2 after 30 days of immersion.