Preparation And Performance Study On The Anti-erosion Coatings Of Hydraulic Steel Members

The corrosion of steel structure will seriously affect its strength under the action of stress,and the increase of corrosion degree will lead to the continuous decline of strength.The economic loss caused by metal corrosion is as high as hundreds of billions of dollars every year in our country.At present,the main protection method of hydraulic steel structure in China is coating protection.However,there is a great difference between the inland river environment and the marine environment in the corrosion of steel structures.The erosion wear of the coating is serious in the environment of high flow velocity and sediment concentration in the inland river,and the factors that lead to the coating damage are not only corrosion,but also the erosion is more prominent.The protection of steel members in the river is very serious.Thermosetting epoxy resin can have a variety of liquid,viscous,solid and other forms.The cured epoxy resin has excellent mechanical properties and bonding properties.Especially for metals,it has strong adhesion and low curing shrinkage,it has a wide range of applications in coatings.Graphene is a new two-dimensional material with a monolayer thickness of about 0.335 nm,its diameter is about a few microns to a few hundred microns.The ? bond formed by sp2 hybridization of every two carbon atoms in graphene makes graphene have excellent mechanical strength and mechanical properties.Therefore,the erosion resistant coating prepared in this paper is based on epoxy resin,and graphene microchip(GNP)is the main functional filler.The main purpose of this paper is to prepare graphene / epoxy resin(GNP/EP)anti-erosion coating by dispersing graphene microchips into epoxy resin uniformly,the erosion resistance and other performance in the environment of silt flow erosion are also tested in this paper.In this paper,GNP/EP anti-erosion coating was prepared by pre-dispersion method.According to the erosion characteristics of high velocity sediment-bearing flow in inland river,a erosion simulation device which can quickly evaluate the erosion resistance of coating is set up.The erosion weight loss of the coating on the sediment erosion wear device is taken as the main index.Through single factor test and orthogonal test,the optimum content of each component of the coating is obtained as follows:the content of silane coupling agent KH-550 is 6wt% of epoxy resin,the content of silane coupling agent is 3wt% of epoxy resin,and the content of curing agent triethylenetetramine is 17.43wt% of epoxy resin.On this basis,liquid nitrile rubber(LNBR)was added into GNP/EP composite coating by physical blending method,and LNBR/GNP/EP composite coating was prepared.Then the erosion resistance,water resistance,aging resistance,adhesion and mechanical properties of GNP/EP composite coating and LNBR/GNP/EP composite coating were tested,and the dispersion of graphene in the coating and the surface morphology of the coating were characterized.The results show that the tensile strength of the coating is increased by 29.9%,the elongation at break is increased by 51.1%,and the erosion resistance of the coating is greatly improved by the addition of GNP.Compared with the epoxy asphalt coating used in the current hydraulic specifications,GNP/EP composite coating has better erosion resistance,water resistance and aging resistance.It is found that the addition of a certain amount of LNBR can effectively improve the erosion wear resistance and mechanical properties of the composite coating,when the content of LNBR is 2phr,the erosion resistance of the composite coating is the best,and the tensile strength of the composite coating is increased by 21.60%,the elongation at break increased by 61.07%.