Preparation Of Novel Nano-hybrid Composites For Microwave Absorbing And Electromagnetic Interference Shielding

In recent years,one-dimensional nanomaterials and two-dimensional graphene have received more and more attention in the field of electromagnetic wave absorption and electromagnetic interference shielding due to their unique structure and performance,but the single material has poor impedance matching which could affect their performance.Therefore,other components can be introduced to construct the composite material so as to take advantage of the multi-component and multi-level coupling and synergistic effect in the composite material to meet the requirements of new electromagnetic absorbing materials and electromagnetic interference shielding materials.In this paper,the different precursors were selected to prepare different precursor nanofibers by electrospinning method and subsequent heat treatment,and then the two kinds of composite nanofibers with excellent absorbing properties were obtained.Thereafter,two kinds of nanofiber-graphene composite films having excellent electromagnetic shielding properties were obtained by mixing with graphene oxide and subsequent heat reduction.The specific research contents are as follows:1.Fe-Ni/C nanocomposite fibers were prepared by electrospinning combined with high temperature carbonization.The effects of electrospinning parameters and carbonization temperature on the morphology and the chemical composition of nanofibers and the effects of carbonization temperature on the absorbing properties were discussed.The experimental results show that the Fe-Ni/C nanocomposite fiber prepared at 800? has a maxmum effective absorption bandwidth of 9 GHz when its thickness is 2.75 mm and it is expected to be used to prepare new absorbing materials with light weight and wide absorption bandwidth.2.SiC nanofibers were prepared by electrospinning and calcination.The effects of electrospinning parameters and calcination conditions on the morphology and chemical composition of nanofibers were investigated by various characterization methods and the absorbing properties and absorbing mechanisms were also discussed.The results show that the minimum reflection loss RLmin can be achieved-40 dB at-15.8 GHz when the thickness of the prepared SiC nanofiber is 1.6 mm and the effective absorption bandwidth of it is 3.8 GHz,showing excellent absorption capacity for electromagnetic waves.3.Different ratio of Fe-Ni/C nanofibers-GO composite membranes and SiC nanofibers-GO composite membranes were prepared by drop-coating method,and they were reduced to obtain corresponding nanofibers-rGO composite membranes.Their morphology composition were studied by various characterization methods and the effects of nanofiber content on the electrical conductivity and electromagnetic shielding performance of the composite membrane were also studied.Degree of reduction by pyrolysis reduction and their electrical conductivity and electromagnetic shielding performance were tested separately.The results show that the electromagnetic shielding performance of the composite membrane is optimal when the mass fraction of nanofibers was 3wt%and the specific electromagnetic shielding effectiveness of Fe-Ni/C nanofiber-graphene(rGO)composite film can reach 2077 dB·mm-1,the specific shielding effectiveness of SiC nanofiber-graphene(rGO)composite film can reach 1769 dB·mm-1,which are ideal materials for preparation of ultra-light and ultra-thin electromagnetic shielding materials.