Preparation And Thermal Conductivity Study Of Metal-graphene Composites

With the electronic components developing towards miniaturization,integration and multifunctional direction gradually,the working frequency and power density are increasing,followed by several cooling problem.If large amounts of heat can not be spread timely,the lifespan,reliability and stability of equipment will be affected seriously.Therefore,efficient thermal management is usually performed inside the electronic device to achieve the purpose of rapid heat dissipation.Among them,searching for the heat dissipation material which has good performance becomes an important breakthrough.However,the traditional metal heat dissipation materials have become useless to meet the current heat-dissipating requirements because of its high thermal expansion coefficient and density.Graphene exhibits excellent mechanical and thermal properties,thus it is an ideal heat dissipation material.In this paper,a kind of metal-graphene composite film with high thermal conductivity is prepared utilizing special structure and performance of graphene,under the premise of preserving the two-dimensional heat transfer channel of graphene,and the thermal conductivity of composite materials are explored through experiments,which is of practical significance to the heat dissipation of electronic equipment.In this paper,graphene oxide is prepared by modified Hummers method and graphene oxidecopper composite is prepared by electrophoretic deposition in aqueous solution of graphene oxide.The effects of preparation process on film-forming properties,micro-morphology and cross-sectional thickness are investigated by SEM and other characterization methods.Electrophoretic deposition is carried out in monolayer or less-layer graphene oxide solution,and the deposition time is within the corresponding optimal film-forming time.After drying in a vacuum oven at 40 ° C for 12 h,the surface morphology of the prepared films is good.As the increase of concentration of graphene oxide aqueous solution,deposition voltage and time,the folds on the film surface and the thickness of the films increase.As the voltage increases,the space between the film layers is also increasing,wherein when the voltage is 20 V,the convergence is most closely.This preparation method can also manufacture different shapes and sizes of composite films by adjusting the shape and size of the substrate,which has great flexibility.The steady-state method is used to test the thermal conductivity of the above composite films(with 50?m-thick copper substrate).When the deposition voltage and time is 60 V and 5min,respectively,in 1g/L aqueous solution of graphene oxide,the total thickness of the composite film is 53.35?m,and the thermal conductivity is 494 W /(m · K),which is increased 24% compared with the thermal conductivity of pure copper.The thermal conductivity increases with the rise of deposition voltage and time,and the more effective way to increase the thermal conductivity is increasing deposition voltage.In order to further optimize the thermal conductivity,the substrate-free film is treated by spark plasma sintering to obtain the metal-graphene composite with copper nanoparticles.On the one hand,the nanoparticles inserted between the layers of graphene prevent the stacking and aggregation of graphene sheets and ensure the good laminar plane structure.On the other hand,the nanoparticles can enhance the longitudinal thermal conductivity of the film.The thermal conductivity of metal-graphene composite film is 574 W/((m·K),which is increased 44.2% compared with the thermal conductivity of pure copper.