Preparation, Microstructure And Properties Of Graphene/Copper Composite Materials

In this paper, the graphene reinforced copper composites were prepared with the copper powder and the graphene powder as raw materials. The copper powder and the graphene powder were mixed in ethanol, after ultrasonic vibration and dry were pressed into blocks,and then were sintered into composites in the vacuum tube furnace. The microstructure of the prepared graphene/copper composites was observed, and the changes of the microhardness,the compressive yield strength and elastic modulus with the adding amount of the graphene,the prefabrication pressure, sintering temperature and holding time were measured and analyzed. In addition, the thermal expansion coefficient and tensile property of graphene/Cu composites were also measured.The results of the microanalysis show that the graphene reinforced copper composites can be successfully prepared by powder sintering method, and the microstructure characteristic are the equal axial Cu grains composing the matrix and film-like graphene distributing at the grain boundaries. With the increase of the content of graphene and the increase of the prefabricated pressure, matrix grains of the graphene/copper composites are refined to some extent. In addition, with the increase of sintering temperature and holding time, the matrix grain size of graphene/copper composites increased obviously.The results of the microhardness and compression tests show that the preparation technology has obvious influence on the mechanical properties of the graphene/copper composite. With the increasing of sintering temperature and holding time, the microhardness,the compressive yield strength and the elastic modulus increase at first and then decrease, and reach the maximum when the sintering temperature is 950℃ and the sintering holding time is60 min. With the increase of the content of graphene, the mechanical properties of the graphene/Cu composites increase firstly and then decrease. When the addition amount of graphene is 20 mg in each 15 g copper, the microhardness, the compressive yield strength and the elastic modulus have maximums. In addition, with the prefabricate pressure increasing from 30 MPa to 150 MPa, the microhardness, the compressive yield strength and the elastic modulus of the graphene/Cu composites increase gradually.The results of comparing with the pure copper specimen show that the addition of the graphene can significantly improve the properties of the graphene/Cu composites. When the prefabricating pressure is 60 MPa, the content of graphene is 20mg/15 g copper powder, the Sintering temperature is 950℃ and the holding time is 60 min respectively, the microhardness,compressive yield strength and elastic modulus of the graphene/copper composites are 58 HV,182Mpa and 45 Gpa respectively, and increase by 34%, 127% and 50% respectively comparing with the pure copper specimen.The sintered copper specimen and graphene/Cu composite specimen were hot rolled, and then tensile test were carried out. The results show that the tensile yield strength and tensilestrength of the graphene/Cu composites are not obviously higher than the pure copper specimen, but the elongation after fracture increase to a certain degree.The thermal expansion analyses of the graphene/copper composites and the pure copper samples are carried out. The results show that the thermal expansion coefficient of the graphene/Cu composites is lower than pure copper samples, and it is very obvious in the temperature range from 150℃ to 800℃.