Preparation And Properties Of New Graphene Materials By Electrochemical Deposition

Civil aircraft is an important means of transportation in China,the safety and reliability of its structure and equipment have always been the focus of civil aviation engineering.A large number of resin matrix composite materials with lower conductivity than traditional metal materials are used in modern civil aircraft structure.When the surface of aircraft structure or equipment gathers static electricity and cannot be effectively released,the discharge effect will cause damage and interference to the aerodynamic shape,communication signal,etc.to varying degrees,and cause a serious threat to the aviation operation safety.Aiming at the problem of electrostatic discharge of composite structure aircraft,the conductive paint layer plays an important role as the key link to transfer the static electricity.In this study,graphene and carbon nanotubes were combined to form conductive fillers by simple,controllable and environmentally friendly electrochemical deposition method,and then epoxy primer was directly modified to prepare aviation antistatic coating.The morphology,phase and dispersion of the filler were characterized,and the optimal preparation parameters were explored.The graphene/carbon nanotubes/epoxy composite coating was characterized and its properties were studied,and the relationship between its thermal stability,conductivity and the amount and thickness of addition was revealed.On this basis,the electrostatic characteristics of the composite coating are tested,and the relationship between the electrostatic accumulation,dissipation and flashover characteristics and the factors such as addition amount,thickness,time and voltage is explored.The engineering data and analysis results are obtained.The main research contents are as follows:A carbon nanotube/foam nickel(CNTs/NF)composite electrode was prepared by using nickel foam(NF,Ni foam)as substrate and impregnating method to make nickel foam coated with a layer of carbon nanotubes.Then,graphene/carbon nanotube/foam nickel(rGO/CNTs/NF)composites were obtained by depositing a layer of reduced graphene oxide(GO)on the surface of the composite electrode by electrochemical deposition.The morphology,phase,structure and functional group of rGO/CNTs/NF were characterized by SEM,XRD,Raman and FTIR,and optimum preparation conditions were determined.Finally,the graphene/carbon nanotube(rGO/CNTs)composite structure was obtained by using electrolysis oxidation etching to remove foam nickel,and the morphology and dispersibility of rGO/CNTs composite were studied by SEM and UV-vis.The results showed that carbon nanotubes on surface of nickel foam treated by coupling agent significantly increased,which was conducive to the construction of three-dimensional rGO/CNTs structure.After electrochemical deposition,graphene oxide was successfully reduced to graphene,and the deposition effect was the best when the deposition current was 0.005 A,the deposition time was 5min,and the solution concentration was 1 mg/ml.The reduced graphene oxide has some oxygen-containing groups,it can be used as the natural dispersant of carbon nanotubes.Moreover,the intercalation and isolation of the two make the rGO/CNTs structure maintain good dispersion in the water dispersion system.rGO/CNTs/EP coating was prepared by adding rGO/CNTs structure as filler into epoxy resin.The morphology of the coating was characterized by SEM,and its thermal stability was studied by TGA.The coating was prepared under different adding amount and thickness on the glass fiber laminate.The resistivity and adhesion were tested and the influencing factors were studied.The results show that the cross-section of rGO/CNTs/EP coating is coarser than EP,and rGO/CNTs constitute a three-dimensional network structure with uniform overall distribution,and the composite coating with 5wt% filler has fewer defects;the heating stability increases with the increase of filler mass fraction;From 0wt% to 1wt% and from 1wt% to 3wt%,the surface resistivity decreased by four orders of magnitude,and then the decrease was not obvious;Under the same conditions,the surface resistivity of rGO/CNTs/EP coating is lower than that of CNTs/EP coating,and the maximum decrease is 55.5% when the amount of additive is 3wt%.The static electricity was applied to the rGO/CNTs/EP coating and measured.The distribution and dissipation characteristics of the static electricity on the coating,as well as the influence of the addition amount and the thickness of the coating on the dissipation were studied.Then,the flashover voltage along the surface of the coating was measured before and after applying static electricity.The factors influencing the flashover voltage were discussed,and the changes of the coating surface state before and after charging and flashover were analyzed.The results show that the distribution of the surface charge of the coating is that the area with the most intensive charge is the center of the coating,and it is radiated around;The static electricity decays with time,and the static electricity decay rate increases with the increase of adding amount and the increase of coating thickness;The surface flashover voltage of EP coating decreases with the accumulation of static electricity.The flashover voltage of composite coating is generally lower than that of EP coating and decreases with the increase of filler,and increases after charging;The contact angle with water decreases after charging,and flashover causes different degrees of damage to the composite coating,especially the composite coating with 5wt% filler is the most significant.