Research On Graphene Preparation Technology And Shielding Performance

Graphene is a periodic hexagonal lattice honeycomb two-dimensional crystal composed of a layer of carbon atoms.It has excellent and unique physical,chemical and optical properties such as optics,electricity,magnetism and dynamics.Its hardness,electrical conductivity,and thermal conductivity have exceeded most of the materials.These excellent properties make graphene materials have extremely broad application prospects in the fields of high-performance composite materials,smart materials,electronic devices,solar cells,energy storage devices and drug carriers,and may revolutionize these related industries.graphene film materials prepared by chemical reduction and thermal reduction methods have poor electromagnetic shielding performance due to the dispersion and conductivity of graphene in the matrix.Although graphene prepared by CVD method can improve its electromagnetic shielding performance,related research is still in the exploratory stage,and the experimental data is very discrete,and no reliable application scheme has been formed.In this paper,copper foil was used as the growth substrate,graphene film was prepared by CVD method,and the growth changes of graphene film under different process parameters were compared.Through orthogonal optimization of process parameters,a high-quality single-layer graphene film was prepared.The electromagnetic shielding performance was studied;due to the limitation of the shielding performance of a single-layer graphene film,a method to improve the electromagnetic shielding performance by superimposing the number of layers was proposed and verified through experiments.This paper mainly carried out the following specific research work.The chemical vapor deposition method is used to grow and transfer the graphene film on the copper foil,and the quality of the graphene film is optimized under different growth process parameters through the optimization method.The experiment explored the influence of different methane flow,growth temperature and growth time on the quality of graphene film,and optimized the transfer method of graphene film,and finally found the optimal process for graphene film growth and transfer.The results show that,within a certain range,increasing the methane flow rate,increasing the growth temperature,and increasing the growth time can all improve the quality of graphene film formation.When the methane flow rate is 15sccm,the growth temperature is 1030°C,and the growth time is 30minutes,the performance of the prepared single-layer graphene film is better.The electromagnetic shielding theory and optical transmittance of single-layer graphene films are studied,And designed experiments to use a transparent quartz substrate as a control group to test the electromagnetic shielding performance and transmittance of graphene film samples prepared under different processes.Find the optimal process parameters through testing.Finally,the average electromagnetic shielding performance of the single-layer graphene film is 1.2dB,and the average transmittance in the 400-800nm band is 96%.Since the electromagnetic shielding performance of single-layer graphene film cannot reach the expected effect,a method of stacking single-layer graphene film is proposed to prepare multilayer graphene film samples,and the number of layers and electromagnetic shielding effectiveness of the graphene film samples The relationship was analyzed and studied.With the increase in the number of layers of graphene film samples,the electromagnetic shielding effectiveness is continuously increasing.When stacked to four layers,the average shielding performance at 12-18GHz is 4.39dB.This paper carried out systematic experiments on the preparation and transfer process of graphene,and explored the feasibility of graphene film materials to achieve electromagnetic shielding effects.Research shows that the graphene film prepared under the optimized process scheme achieves the expected electromagnetic shielding effect after superposition,laying a foundation for further expanding the application of graphene film.