Research On Preparation And Properties Of Copper-graphene Composites

In this paper, less layer of graphene made by a redox method was used to prepare amixed-powder consisting of layers of graphene and micron copper.Firstly, the method ofhigh-speed mill and ultrasonic dispersion technology process was used for the preparationof less-layer graphene and the copper-graphene mixed powder. The copper-graphenecomposites were prepared by the hot pressing sintered method using the above mixedpowder. The Scanning electron microscopy (SEM) was used to analyzes the morphologyand structure of the graphene, copper powder, the mixed powder, and it was also used toanalysis the surface of the copper-graphene composites, the fracture surface, the frictionsurface, morphology of the wear-counter etc; the XRD method was used to test the phasecomposition of graphene, the mixed powder as well as the copper-graphene composites.The tensile mechanical properties of the composites were tested on the universal testingmachine.The four-terminal method was taken advantage to test the electronic conductivity;the Archimedes method was used to test the density of the composites;the micro-hardnessof the copper-graphene composites were measured by the metallographic micro-hardnesstester; the friction and wear testing were were conducted on the friction-wear tester.The SEM graphs of the graphene showed that thecollective multilayered graphenelayerswere separated into the monolayer graphene which was substantially transparentafter the ultrasonic dispersion. Meanwhile, in the mixed powder prepared by thismethod,the copper particles were adhered to the monolayer graphene sheets uniformly,with no agglomeration occured in the mixed powder. Through XRD analysis of graphenewe can see that the diffraction peak of (002) crystal plane of the graphene disappears,meanwhile, the other diffraction peaks of crystal plane have different degrees ofdecreasement, indicating that the ultrasonic dispersion techniques can strip the grapheneeffectively.The analysis of density, fracture morphology, thermal conductivity performance andthe XRD anlysis of the composite sintered at different temperatures and different sinteringstress showed: the best sintered temperature of the composite was800℃and the bestsintered pressure was25MPa with vacuum atmosphere (10-5Pa). Through the property analysis of composite materials, we can draw the conclusionthat the relative density of the composites increased with the increase of graphene content,with the highest value of96.68%. Resulting fromthe graphene insertion, the binding forceamong the copper atoms decreased and the elastic modulus of the composites decreasedobviously. The fracture mechanism of the composites ranged from ductile fracture tobrittle fracture, and the fracture strength ranged from210Mpa to142Mpa with the contentof graphene ranging from1%to5%, comparing with thestrengthof the copper declined.The electrical and thermal conductivity of composites have a property of anisotropism.With the increasing content of graphene content, the electronic and thermal conductivityfirstly decreased and then increased, with the lowest value found atthe point of graphenecontent between3%to4%. The friction and wear experimental showed that the frictionand wear varied from the adhesive wearmechanism of pure coppertothe abrasive wearmechanism of the composites, and the friction coefficient and wear volume reduced to alow value, and all thisindicated that the addition of the graohene can improve the wearresistance of pure copper.