Preparation Of Graphene Nanoplatelets By Ultrasonic Stripping And Its Application In Anticorrosion Coatings

Graphene is a new type of two-dimensional nanomaterials composed of single layer carbon atoms.It has the characteristics of large specific surface energy,good flexibility and high strength and hardness.Adding graphene and its derivatives into the traditional anti-corrosion coating system,using its special small size two-dimensional sheet structure to form dense physical shielding layer can reduce the penetration of corrosion factor to the matrix material and greatly enhance the coating pair substrate protection,the corrosion rate of materials in the corrosive environment will be greatly reduced.Graphene nanosheets were prepared by the method of expanded graphite intercalation,and the conditions were optimized.Then grafted surface modification of graphene was carried out to improve its dispersibility in organic solvents and improve the overall performance of anti-corrosion coating.These are the main topics of this project research objectives.In this experiment,exfoliated graphite was obtained by intercalation and oxidation of flake graphite with different mesh numbers,then different layers of graphene nanosheets were obtained by ultrasonic stripping,and the conditions were optimized and screened.The silane coupling agent(KH-560)was used to modify the surface,and characterized by FTIR,XRD,SEM and TEM.The modified graphene nanosheets were added into the traditional epoxy zinc rich anticorrosive coating formulation as a filler replace part of the zinc powders to prepare a new graphene marine heavy duty coatings,and the effects of different graphene nanosheets with different layers and different additions on the coating properties were explored.The result indicated that,expandable oxidized graphite was pyrolyzed at 800℃for 30 s to obtain expanded graphite with the largest expansion volume.The maximum volume of the expanded graphite for the 80 and 100 mesh flake graphite was 215mL/g and 85mL/g,and graphene nanoplatelets could be stripped out of 30~50 and 6~20 layers by ultrasonic 5 hours at a temperature of 50℃ respectively.After KH-560 modification,the dispersibility of graphene nanosheets in organic solvents can be improved.In this experiment,a small amount of modified graphene nanosheets was added to the traditional epoxy zinc-rich anticorrosion coatings,instead of about 40% of zinc powder,and make the performance of the anticorrosive coating improved.The experimental results show that the modified graphene nanosheets coating with less layers has better performance.The coating has the best comprehensive performance when its addition amount is 0.5%.