Study On Anticorrosion Property Of Silica Coated Graphene Oxide/Epoxy Composite Coating

In recent years,the development of the national economy has shown an exponential upward trend,the demand for energy exceeds the demand.The development of oil and gas pipeline transportation is increasingly rapid,long distance,large caliber,cross-border international oil and gas pipeline came into being.Then,metal corrosion is becoming more and more serious.However,with the increasingly severe application field and corrosion environment,the traditional coatings at present cannot satisfy the current need.It is urgent to develop new and effective metal protection technology.Epoxy coatings are considered as one of the eager candidate materials for metal protective anticorrosive coatings because of its excellent permeability resistance and chemical resistance.However,due to the brittleness of the 3-D network structure of epoxy resin coating,it is not difficult to produce cracks,resulting in a large number of holes appeared on the surface.Some corrosive medias can through the micropore and crack penetration to the surface of the substrate and accelerate the corrosion of the metal surface.Therefore,the preparation of high performance epoxy resin anticorrosive coatings is a major subject in the field of metal protection.In this paper,a kind of high performance silica coated graphene oxide?SiO₂-GO?nanosheets was prepared by sol-gel method,which can effectively reduce the number of holes on the coating surface when it as a filler was homogeneously dispersed in the epoxy coating.Then a series of GO/epoxy and SiO₂-GO/epoxy composite coatings with different contents?0.1 wt%,0.5 wt%,1 wt% and 2 wt%?of GO and SiO₂-GO as fillers were prepared and investigated for adhesion,hardness and impact resistance.Results showed that the mechanical properties of all coatings added with GO and SiO₂-GO have been considerably improved.Among them,the addition of 0.5 wt% SiO₂-GO as filler in epoxy matrix shows the best mechanical properties,as evidenced by the adhesion increased from 1.55 MPa to 2.11 MPa.Subsequently,a series of electrochemical tests were conducted out to evaluate the corrosion resistance of the coatings.The results exhibited that the corrosion protection efficiency of the coatings increased from 67.01% to 99.58%.The improvement of corrosion resistance properties was attributed to the Si-OH group produced by TEOS hydrolysis could form a chemical bond with the epoxy resin,which greatly increases the adhesion strength between the coating and the steel substrate,and further increased the anticorrosion performance of the coating.Furthermore,the peel adhesion test also proved that SiO₂-GO nanosheets could enhance the bond strength between the coating and the steel substrate,and obviously reduced the cathodic peeling of the coating surface.