Characterization And Mechanical Properties Of GO/Cu Composites Prepared By Reverse Pulse Electrodeposition

Having a large number of oxygen-containing functional groups on the surface and edge,graphene oxide(GO)can form a stable and homogeneous solution.It is worth making further studies on the mechanical properties of GO/Cu composites prepared by reverse pulse electrodeposition,and GO is strengthening phase.In this study,graphene oxide was prepared by modified Hummers method.The GO/Cu composites were prepared by reverse pulse deposition in copper electrolyte with different content of graphene oxide.The surface morphologies,compositions and the microstructures of GO and Cu/GO composites were characterized by SEM,TEM,EBSD,XRD,FTIR and so on.Then the mechanical properties of GO/Cu composites were studied by nanoindenter,microhardness tester,tensile and fatigue testers,the results showed as follows:(1)The graphite was oxided and delaminated effectively.The interplanar spacing of GO is 0.775 nm,and there are a large amount of oxygen-containing functional groups on its surface.The orientation of the copper matrix in GO/Cu composites inclined to(111),while the electrodeposited pure Cu inclined to(110).The grain sizes of all GO/Cu composites are smaller than that of pure copper and the density of twin boundary in GO/Cu composites is higher than that of pure copper.(2)The results of nanoindentation tests indicated that the load-depth curves of GO/Cu composites do not exhibit multiple displacement bursts.Comparing with pure Cu,when the concentration of GO in bath is 0.5 g/L,the values ofhardness,Young's modulus and microhardness of GO/Cu composite greatly increased,the values are 2.2 GPa?153.6 GPa and 1.35 GPa,respectively.(3)Tensile properties of GO/Cu composites were studied.It was found that the plasticity of GO/Cu composites was higher than that of pure copper.When the concentration of GO in the bath is 0.2 g/L,the uniform elongation of GO/Cu composites reaches 18.4%,which is 1.4 times of pure copper.(4)The results of high cycle fatigue of pure copper and 0.2 GO composites showed that the fatigue strength of pure copper is higher.The morphology and dislocation structures of 0.2 GO composites and pure Cu were characterized and analysed.It was found that the pure copper samples mainly formed amounts of deformation twins under cyclic loading,while the GO in the GO/Cu composites hindered the movement of dislocations.However,GO sheets located at the interface weakened the grain boundaries,which eventually leads to the decrease of the fatigue strength of 0.2 GO composites.