Preparation Of Magnetic Carbon Composite Fiber Materials And Study On Electromagnetic Wave Absorption Properties

With the rapid development of information technology,the electromagnetic radiation problem caused by the wide use of electronic equipment is becoming more and more serious.The key to solve the problem is to develop efficient absorbing materials for electromagnetic wave.At present,a variety of electromagnetic wave absorbing materials have been developed,including magnetic metals,metal oxides,new two-dimensional materials,carbon materials,etc.However,the single magnetic loss or dielectric loss of the material leads to the failure of electromagnetic impedance matching,and the absorption ability is limited.The development of magnetic/dielectric composite absorbing materials can greatly improve the absorbing capacity.In addition,to meet the requirements of miniaturization of electronic equipment and stealth of flight equipment,the development of high performance electromagnetic wave absorbing materials with light weight and thin thickness is also the focus of this field.In this paper,two kinds of ferro-supported magnetic carbon nanofiber composites with solid core and hollow core structures were prepared by electrospinning technology,and microwave absorption of the materials and microwave absorption mechanism were studied.The details are as follows:1.Magnetic Fe/C composite nanofibers were synthesized by electrospinning and carbonization at high temperature.The effects of packing ratio and annealing temperature on microwave absorption properties were studied.The microstructure,composition and magnetism of the materials were investigated by X-ray diffraction,Raman spectroscopy,X-ray photoelectron spectroscopy,scanning electron microscope and magnetometer.The effects of mass ratio and annealing temperature of PAN and Fe（acac）₃ fillers on the microstructure and electromagnetic absorption properties of the materials were investigated.Finally,the optimal PAN:Fe（acac）₃ sample with mass ratio of 1:1 and annealing temperature of 800℃was obtained.In terms of minimum reflection loss:the sample achieves a minimum value of-29.75 d B when the thickness is 3 mm.In terms of absorption bandwidth,the effective absorption bandwidth of the sample with a thickness of 2.5 mm can reach 4.11 GHz（11.52 GHz-15.63 GHz）.2.In order to reduce the material density,Fe/C magnetic carbon nanofibers with hollow structure were prepared by coaxial electrospinning.The performance of the optimized material has been improved significantly while the density is reduced.In terms of minimum reflection loss,the sample achieves a minimum value of-41.60 d B when the thickness is 3 mm.In terms of absorption bandwidth,when the thickness is 2.5mm,the effective absorption bandwidth of the sample can reach 5.07 GHz（12.45 GHz-17.52 GHz）.The excellent absorption ability of magnetic Fe/C composite nanofibers comes from the synergistic effect of dielectric loss（conduction loss,molecular polarization,defect-induced polarization,interfacial loss）and magnetic loss（natural resonance,interactive resonance,eddy current loss）.This paper provides a reference for the preparation of high performance electromagnetic wave absorbing materials with low density,thin thickness and light weight.