Study On The Preparation And Thermal Properties Of Graphene-based Flexible Thermally Conductive Material

Recently,with the rapid development of electronic and aerospace technologies,the degree of integration and power of components has increased greatly,making the thermal management of electronic devices particularly important.However,metal materials,such as copper and aluminum,which are used in many fields of thermal management,which are characterized by high quality,low thermal conductivity,and low flexibility.This is inconsistent with the current microelectronics and light weight characteristics of electronic products.Therefore,the graphene with excellent thermal conductivity.So it's selected as the substrate for the flexible thermal conductive film.At the same time,for the lap joint problem during the preparation of the precursor graphene oxide(GO)film,may be resolved by employing the additives such as carbon fibers(CF)and carbon nanotubes(CNTs).Moreover,the influence of relevant parameters on the overlap,tensile strength,and thermal conductivity of the thermal conductive film was analyzed,and the heat-dissipation effect of the thermal conductive film was tested.So the conclusions are as follows.The effect of additives on the performance of the thermal conductive film: Within the appropriate concentration of graphene oxide,adding a little appropriate amount of carbon fibers and carbon nanotubes,the tensile strength and thermal diffusivity of the flexible thermal conductive film were significantly improved.The reason is that the carbon fiber and the carbon nanotubes added in the flexible thermal conductive film can form a heat conduction path at the overlap of the graphene segment.In addition,due to the difference in size between the added carbon fiber and the carbon nanotubes,the balloon cavity formed when the thermally conductive film is thermally reduced can be filled.The addition of carbon fibers and carbon nanotubes can not only form good heat conduction channels,but also discharge air,and can also be uniformly dispersed in the thermal conductive film,and therefore has significant improvement in thermal conductivity and tensile strength.The influence of temperature and pressure on the performance of the flexible thermal conductive film: Test results of microscopic characterization and macroscopic performance show that the heat reduction and hot-pressing processes have a significant effect on the overlap of the segments in the thermal conductive film.After the thermal reduction process of the flexible thermal conductive film,the gas generated by the decomposition of the oxygen-containing functional group easily impinges on the overlap between the laminae,but when the reduction temperature is further increased,it also occurs with the removal of the oxygen-containing functional group.The change of chemical bond finally caused the thermal diffusion coefficient of the thermal conductive film to mutate at 1000 °C.The use of hot-pressed heat-treated process can improve the problem of lamellar laps caused by thermal reduction.With the increase of pressure,the density of the thermal conductive film also increases,and the lamination of the thermal conductive film remains stable.When the thermal conductive film was treated at 1000 °C and 12 MPa,the thermal conductivity of the flexible thermal conductive film arrived 490.951 W/(mK).Preparation and performance of flexible heat-conducting elements: The heat transfer performance of the graphite-based thermal conductive strip,made by folding and pressing the thermal conductive film,is much better than that of the copper foil.However,when it is built into the flexible heat-conducting element,its cooling effect on the constant-temperature heat sink is slightly inferior to that of the copper foil.The reason is that the contact thermal resistance between different materials will form,and the solder used in the preparation of the flexible heat-conducting element is relatively low.However,the flexible heat-conducting element can reduce the maximum temperature of the heat source from 125.4 °C to 110.6 °C,indicating that it may provide with an excellent heat transfer effect.