Preparation And Performance Study Of Graphene Copper Composite By In-situ Growth

Copper owns very excellent conductive and heat conduction performance,easy processing and cutting forming,have a wide and important applications in electronic appliances,household appliances,defense industry.But the low mechanical strength and low wear resistance,weak oxidation resistance and especially high temperature oxidation resistance limit the application of the copper.Research focus on that improve the strength of the composite material and oxidation resistance by adding alloy phase,particle and the traditional carbon material in the early,but often results in the decrease of copper conductive performance.Graphene was found in the laboratory in 2004,has excellent comprehensive performance,high strength(1100 GPa),high conductive(15000 cm~2/(V·s)),high thermal conductivity(6000 W/(m·K)),large specific surface area and high temperature oxidation resistance confirmed by the experiment.So,graphene is ideal packing for copper.Now,the mechanical strength of composite materials can greatly be improved,but can’t keep the high conductive and thermal conductivity of copper,antioxidant is only used to improve performance of the film.Because it is difficult to disperse graphene homogenously on copper powder,no affinity between copper and graphene lead to weak interfacial bonding force.High quality graphene can grow on copper foil by Chemical vapor deposition,but growth condition is about 1000℃,the copper powder is very easy to adhesive at high temperature.Copper powder are isolated by dispersant,graphene grow at 1000℃by CVD,graphene were characterized by SEM、TEM、particle size analyzer and Raman spectra.By hot pressing molding,the density,conductive、thermal properties and mechanical strength of composite materials were tested.For the first time,oxidation resistance and contact resistance,especially the high temperature performance of GR/Cu were tested,the results are as follows:(1)Graphene grow under the high temperature of 1000℃by CVD,particle size analysis and SEM analysis show that copper powder are good isolated by the dispersant,copper powder is not adhesive at high temperature.After etching copper powder,characterization of graphene by TEM,Raman,XPS mean high quality graphene is obtained.(2)Density of the GR/Cu is 8.76 g/cm~3 by drainage method,close to its theoretical density 8.79 g/cm~3,there are no holes on morphology after polishing,shows that GR/Cu is dense.GR/Cu grain obviously are observed than copper smaller by metallographic,that graphene prevents the copper grain grow up in the process of hot pressing sintering.(3)Electrical and thermal conductivity of copper and GR/Cu is equivalent,and is isotropic.Electrical conductive and thermal conductivity of GR/Cu are 96%IACS,384W/(m·K),respectively.Tensile strength of GR/Cu relative to copper increase 10%,while commercial cold rolled copper by hot-pressing process annealing,its tensile strength is lower than GR/Cu 27%.(4)By testing the contact resistance,ICR values of GR/Cu is lower than copper 14%at room temperature,that shows graphene can enhance the interface electric conductivity.Sustained oxidation under 6 h in 100℃,130℃,160℃,190℃,,the ICR of copper was 1.08Ω,Relative to copper at room temperature increase 3 times,its growth rate is 5.5 times of GR/Cu.Graphene on interface conductivity at high temperature does not decrease because of graphene has not been oxidized and copper coated graphene are not also oxidized.By the polishing to change the thickness of GR/Cu and GR/Cu of oxidation,GR/Cu still have this advantage,because it is body material rather than growth of graphene on the surface.