Preparation Of Graphene Composite Coatings On Carbon Steel Surface And Their Anticorrosion Properties

In recent years,the corrosion of carbon steel became the main problem in the use process.Organic coating has become a simple and effective anticorrosion method through barrier,corrosion inhibitor or electrochemical protection for metal.Due to the special structure of graphene and excellent physical and chemical properties,graphene has a very broad application prospect in corrosion protection.In this paper,stable aqueous dispersion of polymer functionalized graphene sheets was prepared by hydrolyzed styrene-maleic anhydride copolymer assisted electrochemical exfoliation technique.Well dispersible graphene/polypyrrole composite was prepared by in situ polymerization using the polymer functionalized graphene as stablizer.Then,graphene/organic siloxane modified resin treatment solution and graphene/polypyrrole/organic siloxane modified resin treatment solution were prepared by solution blending and used for the corrosion protection of Q235 carbon steel,respectively.Effects of the type and content of corrosion inhibitor and coating thickness on the performance of graphene composite anticorrosion coating were investigated.Graphene and graphene/polypyrrole composite were characterized by SEM,TEM,AFM,XRD,FTIR and Raman.The results show that graphite electrode was successfully electrolytic exfoliated to monolayer graphene in the aqueous solution of hydrolyzed styrene-maleic anhydride copolymer.Hydrolyzed styrene-maleic anhydride copolymer were adsorbed on the surface of graphene,giving the aqueous dispersion of functionalized graphene excellent stability.The polymer functionalized graphene and polypyrrole are combined successfully and exhibit excellent water dispersibility.The corrosion resistance of graphene composite coating were studied by electrochemical impedance spectroscopy,polarization curve,copper sulfate intravenous drip and salt water immersion test.Results show that the addition of graphene significantly improved the anticorrosion properties of the graphene/organic siloxane modified resin composite coating.When graphene content is 0.10%,the anticorrosion performance of graphene/organic siloxane modified resin composite coating is the best.The coating has the better anticorrosion properties with the thicker of the coating.Corrosion inhibitors,sodium molybdate and phosphoric acid,have no obvious effect on the anticorrosion performance of composite coating.Sodium metavanadate and phytic acid can significantly improve the anticorrosion performance of composite coating.When the content of sodium metavanadate and phytic acid is 0.06% and 0.4%,respectively,the anticorrosion performance of compoisite coating is the best.Composite coating after adding corrosion inhibitors(phytic acid or sodium metavanadate)exhibited the improved anticorrosion performance when graphene content is 0.15% and 0.10%,respectively.The addition of graphene/polypyrrole significantly improved the anticorrosion properties of the graphene/polypyrrole/organic siloxane modified resin composite coating.When graphene/polypyrrole content was 0.4%,the anticorrosion performance of graphene/polypyrrole/organic siloxane modified resin composite coating is the best.When the content of phosphoric acid and sodium molybdate was less than 0.2% and0.02%,respectively,the anticorrosion performance of composite coating is improved.A small amount of sodium metavanadate have no obvious effect on the anticorrosion performance of composite coating,but the addition of phytic acid will reduce the anticorrosion performance of composite coating.With the increase of the content of various corrosion inhibitors,the anticorrosion performance of graphene/polypyrrole/organic siloxane modified resin composite coating will be decreased.