Research On The Effect Of Reduced Graphene Oxide On The Corrosion Resistance Of Zinc-rich Epoxy Coatings

Zinc-rich epoxy coatings have important applications in the corrosion resistance of metal.Epoxy resins show high tensile strength and high chemical resistance and are widely used in coatings.However,epoxy resins possess low electrical conductivity,high crosslink density,which reduced toughness and impact resistance,which make them vulnerable to microcracking during the use and limit their applications.The neat zinc-rich epoxy coating has high content of zinc powder,the flexibility is not very well,and can produce the zinc chloride mist in the use process,which is harmful to the environment.In order to improve the corrosion resistance of zinc-rich epoxy coatings,two methods for in situ reduction of graphene oxide were used in this thesis.The surface morphology,physicochemical properties and corrosion resistance of reduced graphene（rGO）/epoxy zinc-rich composite coatings were systematically studied.1.Zinc-reduced graphene oxide（Zn/rGO）was introduced into zinc-rich epoxy coatings to enhance the corrosion resistance.Infrared spectrum results indicated that Zn/rGO displays a broad diffraction peak at 23.3°close to that of purchased graphene,indicating the partial recovery of the graphite crystal structure.The interaction between zinc powder and graphene oxide（GO）nanosheets could simultaneously achieve the reduction and dispersion of GO and rGO nanosheets,respectively.Scanning electron microscopy,X-ray diffraction,Raman spectroscopy,potentiodynamic polarization（Tafel）,electrochemical impedance spectroscopy（EIS）and salt spray test were used to characterize the corrosion protection performance of coatings.The results demonstrated that the well-dispersed r GO nanosheets decreased the coating porosity and provided effective protectiveness for zinc particles,thus Zn/rGO generating improved barrier property against aggressive species and long-term cathodic protection ability.2.A facile SnCl₂/EtOH solution method is successfully employed towards the in situ reduction of GO in coatings.Compared to the zinc powder reduction solid-phase method,the wet reduction technique can ensure that the reducing agent Sn²⁺has more uniform contact with the graphene oxide,thereby achieving efficient in-situ reduction of the graphene oxide.Through the characterization of video measuring instruments,Sn/rGO composite coating has the smallest corrosion width,and when Sn/rGO is 1%,the corrosion width of the composite coating is 0.529 mm.According to the Tafel curve test,Sn/rGO-1%has the highest E_corr which is-448 mv,while Sn/rGO-1%has the lowest i_corr which is 0.0248μA cm^-2.It shows that the composite coating Sn/rGO-1%has the best corrosion resistance.The results clearly show that the use of SnCl₂/EtOH solution to reduce GO can play an important role in the coating,can effectively improve its corrosion resistance.