Preparation And Properties Of Graphene-based High Thermal Conductivity Composites

With the rapid development of electronic assembly technology,it is urgent to develop a kind of lightweight and high thermal conductivity material to meet the heat dissipation requirements of miniaturization,integration and high frequency electronic equipment.Graphene-based thermal conductivity film has the advantages of light weight,flexibility and high thermal conductivity,which is expected to solve the heat dissipation problem of high-performance electronic equipment.Among them,the preparation of graphene-based thermal conductivity film by graphite oxide reduction method has outstanding advantages such as unrestricted raw materials,large output and simple method,which is considered to be the best method for large-scale industrialization.However,graphene based thermal conductivity film prepared by graphite oxide reduction method has many defects and interlayer voids,resulting in low thermal conductivity,which is difficult to meet the heat dissipation requirements of high heat flux.Therefore,our paper proposes that Vitamin C(VC)can repair defects in graphene and Nickel(Ni)catalyzed organic carbon source to construct phonon transport channel between graphene layers to improve the thermal conductivity of graphene-based thermal conductivity film,providing a new idea for low-cost process preparation of light and high thermal conductivity materials.Preparation of graphene-based thermal conductivity film.Reduced Graphene Oxide(RGO)films were prepared by means of evaporative solvent self-assembly method and hot-press reduction process.Through characterization and performance analysis,the transverse size of GO is between 5.0 ?m and 20 ?m,which is suitable for assembling graphene based thermal conductivity film precursor.The thermal conductivity of RGO film is greatly improved after hot press reduction treatment.Repair graphene defects.The reduced graphene oxide/vitamin C(RGO/VC)composite film was prepared by hot-press reduction process with vitamin C as defect repair reagent.With the increase of vitamin C doping amount,the defect density of RGO/VC composite membrane firstly decreased and then increased.When the defect density was the smallest,the corresponding thermal conductivity reached the maximum.Based on the analysis results,the mechanism of vitamin C defect repair in graphene was deduced.Phonon transport channels between graphene layers were constructed.Catalytic cracking of hydroxypropyl methylcellulose(HPMC)by nanometer nickel particles was carried out in hot-press reduction process.Hydroxypropyl methylcellulose was used to generate multilayer graphene and construct phonon transport channels between graphene layers to prepare the composite films of reduced graphene oxide-nickel-hydroxypropyl methyl cellulose(RGO-Ni-HPMC).The RGO-Ni-HPMC composite membrane showed the best heat conduction performance when the Ni particles were completely wrapped by hydroxypropyl methylcellulose.It could effectively avoid the occurrence of local excessive temperature and had a good heat dissipation and temperature control effect on the heating components.According to the analysis results,the mechanism of Ni catalyzed the growth of multilayer graphene from organic carbon source was deduced.