Preparation And Application Of Carbon Microwave Absorption Materials Modified By Polyaniline

Carbonaceous materials have become a hotspot in the field of electromagnetic wave absorption due to their structural design,light weight,good dielectric properties and well chemical stability.However,pure carbonaceous materials have poor impedance matching performance due to their good electrical conductivity,which makes it impossible to exert their loss capability and achieve efficient attenuation of electromagnetic waves.Recently,the theory of electromagnetic wave absorption and advances in material preparation methods have shown that suitable material composition and structural design are beneficial for improving the impedance matching properties and electromagnetic wave attenuation capabilities of pure carbon materials.However,improving the microwave absorption(MA)properties of materials through composition and structural design is still a challenging,and its influence on the MA properties and mechanism of action need to be further explored.In this regard,this paper proposes the use of de-template and calcination method to prepare carbon-based materials,through the process adjustment to achieve the regulation of material composition,to obtain carbon-based MA materials which possess good impedance matching and strong loss capacity.At the same time,by introducing a conductive polymer material with strong structural design,a carbon-based composite absorbing material with a special microstructure is constructed.The influence of the composition and morphology on MA properties and mechanism of action have been studied deeply.Finally,the carbon-based composite absorbing material is used as a functional agent,which is compounded with a resin to obtain absorbing functional coating and explore its application.The specific research contents are as follows:Firstly,the carbon cap material(MRC-C)with mushroom cap-like structure was prepared by hydrothermal,etching and calcination with tetraethyl orthosilicate,resorcinol and formaldehyde as raw materials.The multi-dimensional analysis of the materials was carried out by field emission scanning electron microscopy,transmission electron microscopy,specific surface area analyzer,Raman spectrometer,Fourier infrared spectrometer and X-ray photoelectron spectroscopy,and the effects of calcination temperature on material composition and morphology were discussed.The electromagnetic parameters of the material were tested by a vector network analyzer to investigate the influence of material composition and morphology change on its MA properties.The results show that samples display obvious mushroom cap morphology,and the improvement of the specific surface area,graphitization degree and carbon and nitrogen content of the MRC-C sample are attributed to the increase of heat treatment temperature.When the heat treatment temperature is 900℃,the prepared MRC-C sample shows excellent MA properties.In the 2-18 GHz range,with a sample thickness of 1.6 mm,the minimum reflection loss at 14.86 GHz is-42.40 dB,and the effective absorbing bandwidth(reflection loss less than-10 dB)is from 12.98 GHz to 17.30 GHz.Secondly,in order to further improve the impedance matching characteristics,the polarization effect and the loss of electromagnetic waves of pure carbon materials.Based on the above research,this paper introduces conductive polyaniline(PANI)nanoarray components on the surface of MRC-C by in-situ polymerization to obtain MRC-C@PANI composite MA materials.The morphological,structural and electromagnetic parameters of MRC-C@PANI composites were characterized and tested.The MA mechanism of MRC-C@PANI composites was discussed.The results show that the introduction of polyaniline nanoarrays on the surface of MRC-C by in-situ polymerization has no effect on the structure of carbon materials.At the same time,the introduction of polyaniline nanoarrays effectively adjusts the electromagnetic parameters of MRC-C materials.Furthermore,the impedance matching of the MRC-C@PANI composites is effectively improved,and finally the MA performance is improved.In the range of 2-18 GHz,the thickness of the MRC-C@PANI composite absorbing material has a minimum reflection loss of-43.1 dB at a frequency of 9.58 GHz,corresponding to an effective absorption bandwidth form 8.52 GHz to 11.44 GHz.Finally,based on the above research,this study proposes to use MRC-C@PANI composite material and waterborne epoxy resin coating as MA functional agent and matrix respectively,and the waterborne epoxy resin-based functional composite absorbing coating was prepared by physical mechanical composite preparation,which is combined with the strong core felt to form a microwave absorption felt(MAF)by impregnation method.The effects of MA agent content on the morphology,mechanical properties,electromagnetic parameters and absorbing properties of MAF were investigated,and the mechanism of MA was analyzed.The results show that with the increase of MA agent in the coating,the surface of the MAF is obviously rough,the mechanical properties and electromagnetic parameters are effectively improved.When the content of the absorber is 10 wt%,the MAF has a minimum reflection loss of-55.90 dB at a frequency of 15.12 GHz with the thickness of 1.4 mm,and the effective absorption bandwidth can reach 4.87 GHz(13.15 GHz～18.00 GHz).It can be seen that the study provides a new design idea for the development of new high-performance MA materials,and provides a theoretical basis and experimental reference for further promoting the practical process of new MA materials.