Preparation Of Graphene / Cu - Based Composites And Study On Their Electromechanical Properties

The high strength high electrical copper-based material is an essential basic material for the modern industry. However, the strength and electrical conductivity of copper matrix composites are usually hard to juggle. In this research, we choosed the excellent mechanical and electrical properties of graphene as the reinforcements to prepare the composites by mechanical alloying and spark plasma sintering (SPS) technology. The work mainly focus on the eefects of concentration of graphene, Co and ball-milling time on the structure and mechanical/electrical of the composites. And the effect mechanism of Co on the mechanical and electrical properties of the composites was also explored. Scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction were used to analyze the phase composition, morphology and structure of the composite powders; the compression performance and tensile properties of the composites were tested by universal testing machine; the eddy-current instrument, microhardness tester, Archimedes water displacement method, the thermal expansion performance of composites were tested the resistivity, hardness, density and thermal expansion respectively.With the increasing of the ball-milling time and graphene concentration, the dispersion uniformity, strength and the hardness of the composites present the increased trend. TEM analysis showed that the graphene sheet had a good crystal structure and compounded with cooper matrix well. The tensile yield strength and compressive strength of 0.5wt% G/Cu composite was 235MPa and 620MPa, which were increased by 95.8% and 3 times compared to pure Cu respectively; the hardness of the 0.5wt%G/Cu was 123HV(increased 36.7%), which was lower than the 0.4wt%G/Cu(128HV, increased by 42%) at the 8h milling time. Under the ball milling time 6 h, the I ACS of the 0.4wt%G/Cu was reached to 81%, which was higher than the 0.5wt%G/Cu composites(66.5%). The hardness of Co doped composites were increased to 152HV (increased by 68.8%).The compressive strength of the Co dopped composites were lower than the G/Cu composites.As for the compressive strength of failure strain were 573MPa(-2.8times to pure Cu) and 52% respectively. In addition, with the increasing of Co concentration, the fracture morphology of the sintered samples changed from the dimples to dissociative fracture, and the IACS showed a drop tendency under the same milling time(the 0.2wt%Co doped composites was reached to 60%).According to the calculations of the first principle we knew that the interfacial bonding energy of G/Cu was 0.484ev without Co doping; a single Co atom and two Co atoms doping, the interfacial bonding energy of G/Cu were-134.9ev and-149.26ev respectively. As a result, it indicated that the two phases interfacial bonding strength were increased with Co doping concentration increasing.