Controllable Fabrication And Electromagnetic Wave Absorption Performance Of Magnetic Nanoparticles And Porous Carbon Composites

With the rapid development of science and technology and the extensive use of electronic equipment,electromagnetic wave pollution is becomig more and more serious.In order to solve this problem,people are devoted to the research of absorbing materials with excellent properties.But the excellent absorbing material must have the characteristics of the thin thick:ness,the light mass,the wide frequency band,the strong absorption.The organic combination of dielectric materials with magnetic materials is an effective way to realize these requirements.Therefore,we constructed a composite system of magnetic nanoparticles and porous carbon materials,and studied the correlation between the components/structures of the materials and their wave absorption properties.(1)We successfully prepared FeOx/Fe/C composites by a simple and gentle method,and controlled the chemical composition of the materials by adjusting the temperature and calcination time.The experimental results show that the chemical composition has a significant effect on absorbing properties of materials.FeO,/Fe/C-750 has various chemical components,such as Fe3O4,Fe,amorphous carbon,graphite carbon and so on,meeting the organic combination of magnetic nanoparticles and dielectric material and shows excellent absorbing performance.Maximum absorption intensity of FeO,/Fe/C-750 composite was up to-37.01 dB and the effective absorption bandwidth(RL<-10 dB)was 6.46 GHz(10.26-16.72 GHz)with a thickness of 2 mm.Due to multiple interface polarization could improve the ability of the dielectric loss of materials and 3 D network structure can make multiple reflection and scatter in electromagnetic wave in the material,causing th e absorption of electromagnetic waves and depletion.The synergistic effect of magnetic Fe/Fe3O4 particles and dielectric carbon can improve the impedance matching,enhancing the EMW absorption performance.(2)We combine mesophthalic anhydride with diphenylamine diphenyl ether via in-situ polymerization method to polymerize different magnetic metal salt precursors and to synthesize porous structure by inducing phase separation.Then reduced carbonization to obtain C/RGO/magnetic nanoparticles porous composite materials.The absorbing performance of different proportion FeCo alloy nanoparticles embedded carbon-based porous materials was studied.There,the maximum absorption intensity of Fe30Co70/RGO/C porous composite is up to-41.09 dB,and when the thickness is 2.5 mm,the effective absorption bandwidth(RL<-10 dB)is 8.13 GHz(9.68-17.81 GHz).This is mainly because different Fe/Co atomic ratios have different effects on the electromagnetic parameters of the materials,which further affects the material's absorbing performance.At the same time,the porous structure not only greatly reduces the density of the materials,but also increases the multiple reflection and dissipation ability of electromagnetic wave in the materials,and improving the absorbing performance of the materials.