Microwave Absorption Properties Of CNT/bioderived Carbon Based Nanomaterials

When the electromagnetic wave hits the surface of the absorbing material,the electro-magnetic wave will attenuates and be absorbed in the transmission process of the absorbing material.After absorbing the electromagnetic wave,the absorbing material absorbs elec-tromagnetic waves and then dissipates electromagnetic energy into other forms of energy,consequently reducing the scattering area of the object's reflection to the radar wave,thus causing the purpose of stealth.In respect of absorbing materials,people pursue the character-istics of multi-band,broadband,strong absorption,light weight and thin thickness,etc.The composite material is one of the highlights for stealth materials and electromagnetic shielding materials.In order to meet the above requirements for the absorbing materials,in this paper,MoS₂/CNT was combined with Fe₃O₄/CPCs and bio-derived carbon photonic crystals were united with magnetic nanoparticles,which achieve the complementarity of performance by the combination of materials,resulting to improved properties.According to the absorbing mechanism of materials,the absorbing materials can be divided into dielectric loss materials and magnetic loss materials.Carbon materials pos-sess low density and large dielectric constant,but the absorption band is narrow and the absorption performance is weak.CNT have a high specific surface area and a large num-ber of suspension keys that can induce the interface polarization.Therefore,nanoflower MoS₂,MoS₂/CNT=10:2 and MoS₂/CNT=10:5 composites were fabricated via hydrother-mal reaction in accordance with the quality ratio of MoS₂with CNT,and the above samples were characterized by XRD,Raman,SEM,TEM.The microwave absorbing properties of the composites were tested by vector network analyzer.The measured results showed that MoS₂was formly distributed on CNT surface for MoS₂/CNT=10:2,mixed with 50wt%of paraffin.The optimal reflection loss of the sample is-50.2 dB at 6.69 GHzwith a thickness of2.87 mm,and the reflection absorption between 1.5 mm-5 mm in the range of 3.4 GHz-13.9 GHz can reach-20 dB,achieving the light weight and strong adsorbing intensity.Fe₃O₄and Fe which are specific magnetic loss absorbents are combined with car-bon materials with low density and dielectric constant to reduce the density of material-s,expand the absorption band and improve the performance of the absorbing wave mi-crowave absorption.Carbon material with the high specific surface area was prepared by the high-temperature activation of natural photonic crystal heteromorphosis butterfly wings in the atmosphere of argon,and then Fe₃O₄and Fe₃O₄carbon photonic crystal composites?Fe₃O₄/CPCs?were synthesized by hydrothermal reaction.The Fe₃O₄and Fe₃O₄/CPC were reduced in the atmosphere of6%H₂/Ar to get Fe and Fe/CPC.Meanwhile,the above samples were characterized by XRD,Raman,SEM,TEM,and the microwave absorbing properties of the composites were tested by vector network analyzer.Compared with Fe₃O₄,Fe and CPCs,Fe₃O₄/CPC and Fe/CPC composites showed excellent microwave absorbing properties.The minimum reflection loss of Fe₃O₄/CPCs at 1.09 mm is-49.7 dB,and the minimum absorp-tion for Fe/CPC is-31.2 dB at 1.18 mm.The effective absorption bandwidth of Fe₃O₄/CPCs and Fe/CPC?RL<-10 dB?at 1.2 mm is 3.8 GHz and 3.5 GHz respectively.