Microwave Absorption Properties Of Metallic Oxide/MWCNTs Composites

Metal oxides(Fe₂O₃/Fe₃O₄/CuO)are dielectric absorbing materials.In this paper,metal oxides are composite with multi-walled carbon nanotubes(MWCNTs).By designing the microstructure,adjusting the preparation path and changing the composition of the composite the wave absorbing performance of the material is enhanced.This thesis uses acidified MWCNTs,potassium ferrocyanide(K4[Fe(CN)6]),CuSO4·5H2O,hydrochloric acid and ammonia as raw materials to prepare MWCNTs/Fe₂O₃,MWCNTs/Fe₃O₄@C and MWCNTs/CuO composite material.FESEM,TEM,XPS,XRD,Fourier infrared spectroscopy,Raman spectroscopy and vector network analyzer(VNA)were used to characterize and analyze the morphology,crystal phase and electromagnetic parameters of the composite.The specific content and results are as follows:(1)Using acidified MWCNTs,K4[Fe(CN)6]and hydrochloric acid as raw materials,polyvinylpyrrolidone(PVP)as a surfactant,MWCNTs/PB composites and their calcined derivatives were synthesized by hydrothermal method.The effects of the preparation conditions and morphology of the calcined derivatives on the sample composition and microwave absorption properties were studied.The results show that the MWCNTs/Fe₂O₃ composite material obtained under oxygen-containing calcination is a hollow raspberry-like material with a large number of mesopores.When the thickness is 4 mm and the frequency is 5.3 GHz,the minimum reflection loss value is-28.6 dB,the maximum effective absorption bandwidth is 4.06 GHz.MWCNTs/Fe₃O₄@C was obtained under anaerobic calcination.The minimum reflection loss value obtained when the thickness is 3 mm is-17.8 dB,and the maximum effective absorption bandwidth is 3.98 GHz.(2)Using acidified MWCNTs,K4[Fe(CN)6]and hydrochloric acid as raw materials,polyvinylpyrrolidone(PVP)as surfactant,MWCNTs/Fe₂O₃ composites were prepared by hydrothermal method.The influence of the molar ratio of raw materials and the morphology of the composite on the microwave absorption properties of the composite was studied.The results show that a large number of acidified MWCNTs are wound on the porous hollow raspberry-like Fe₂O₃ surface and grow uniformly;with the increase of the molar ratio of MWCNTs in the raw material,the microwave absorption performance of the composite first increases and then decreases.When the molar ratio of MWCNTs and K4[Fe(CN)6]is 4.6:1,the minimum reflection loss of the composite material is-53.26 dB when the sample thickness is 1.5 mm,and the maximum effective bandwidth obtained under the same thickness is 5.12 GHz.(3)Using acidified MWCNTs,CuSO4·5H2O,and ammonia as raw materials,MWCNTs/CuO composites were prepared by hydrothermal method.The influence of the molar ratio of raw materials and the morphology of the composite on the microwave absorption properties of the composite was studied.The results show that the acidified MWCNTs are entangled on the surface of the flaky CuO to form a conductive network;as the molar ratio of MWCNTs in the raw material increases,the microwave absorption properties of the composite material first increase and then decrease.When the molar ratio of MWCNTs:CuSO4·5H2O is 2.1:1.5 When the sample thickness is 3.7 mm and the frequency is 5.1 GHz,the best reflection loss value is-48.7dB,and its maximum effective absorption bandwidth value is 3.64 GHz.Figures[27]Tables[6]References[100]...