Preparation And Thermal Conductive Properties Of Modified Graphene/Copper Alloy Thermal Conductive Materials By Electrophoretic Deposition

With the continuous development of science today,electronic products such as sma rt phones and tablet computers have infiltrated people's lives and become an indispensable part.With the continuous improvement of these electronic devices,the internal circuits are developing in the direction of miniaturization,integration and high power,so that electronic products generate a lot of heat during use.For the stable operation of electronic equipment and the long service life,heat must be transferred.Therefore,how to design a heat dissipation device with high thermal conductivity in electronic equipment is particularly important.Graphene,as a two-dimensional carbon nanomaterial composed of sp² hybrid orbitals of carbon atoms,has a hexagonal honeycomb structure.Graphene has excellent optical properties,excellent mechanical properties and electrical properties.It is worth noting that the theoretical value of its thermal conductivity is 5300 W·m^-1·K^-1,which is much higher than the thermal conductivity of all current materials.Its excellent thermal conductivity has attracted the attention of researchers.Common graphene thermal conductive materials come in the form of composite materials,such as metal-based graphene composites,polymer-based graphene composites,and so on.However,these composite materials have the disadvantages of complicated preparation process,unfriendly environment,high energy consumption,and large graphene defects caused during the preparation process,which cannot effectively reflect the high thermal conductivity of graphene.Pulse electrophoretic depositio n,as a method for preparing composite materials,has the advantages of simple operation,highly controllable preparation parameters,environmental friendliness,increased electrode polarization,and reduced hydrogen evolution reaction of the cathode.This method can quickly load on the surface of the substrate.The upper deposited phase gives the desired composite material.In this paper,a graphene-carbon nanotube/copper alloy thermal conductive composite material is prepared by pulsed electrophoretic deposition preparation method with the goal of preparing a graphene thermal conductive composite material with copper alloy as a matrix with high thermal conductivity,?-glycidyl ether propyl trimethylsilane-graphene oxide/copper alloy thermal conductive composite material and epicatechin gal ate-graphene/copper al oy thermal conductive composite material.?1?By adjusting the mixing ratio of graphene and carbon nanotubes,different types of surfactants,the same series of surfactants,pulse current density,and the duration of electrophoretic deposition.The thermal diffusion coefficient of the graphene-carbon nanotube/copper alloy thermally conductive composite material was obtained after testing with a laser thermal conductivity meter.Among them,the thermal diffusion coefficient was highest when Tween60 was used for non-covalent modification of CNT-GNS with a pulse current intensity of 0.2 A/cm²and an electrophoretic deposition time of 9.0 min,the principle is that the four carbons in the carbon-oxygen six-membered ring of Tween60 are all connected with oxyethylene,which is more hydrophilic,and one of the oxyethylene is located in the long hydrocarbon chain,which alleviates the hydrophobicity of the long hydrocarbon chain to a certain extent,so that CNT and GNS are deposited uniformly and evenly on the surface of the copper alloy.The test temperature was reduced from 1.223 cm²/s to 1.086 cm²/s from 50 ? to150 ?.?2?By regulating the concentration of?-glycidyl ether propyltrimethylsilane,the pulse current density and the time of electrophoretic deposition.The thermal diffusion coefficient of the?-glycidyl ether propyltrimethylsilane-graphene oxide/copper alloy thermally conductive composite material is obtained through the test of a laser thermal conductivity meter.Among them,the thermal diffusion coefficient was the highest when the concentration of?-glycidyl ether propyl trimethylsilane was 3%,the pulse current density was 0.2 A/cm²,and the electrophoretic deposition time was 10 min,the principle is that graphene oxide contains more functional groups and is easy to modify.Graphene oxide is surface-modified with?-glycidyl ether propyltrimethylsilane,a silane coupling agent is used to construct a special covalent bond?Cu-O-Si-O-C?between the copper matrix and the graphene oxide to form a thermal conductive bridge,the heat is passed through the heat conduction channel in the form of phonons to reduce the scattering and thus the interface thermal resistance.The test temperature was reduced from1.243 cm²/s from 50 ? to 150 ? to 1.096 cm²/s.?3?By adjusting the concentration of epicatechin gallate,the pulse c urrent density,and the time of pulse electrophoretic deposition,the thermal diffusion coefficient of epicatechin gallate-graphene/copper alloy thermal conductive composite material was obtained through a laser thermal conductivity test.Among them,when the concentration of epicatechin gallate is 0.8g/L,the pulse current density is 0.2 A/cm²,and the electrophoretic deposition time is 7.5 min,the thermal diffusion coefficient is highest.The principle is that the polyphenyl ring structure of epicatechin gallate can have a?-?stacking effect with the carbon six-membered ring on graphene,this non-covalent functionalization can keep graphene structurally intact during the modification process.At the same time,heat flow can be transferred to graphene in the form of?-?stacking.The test temperature was reduced from 1.249 cm²/s from 50 ? to 150 ? to 1.100cm²/s.