具有可设计介孔外壳的中空碳微球及其宽频带吸波性能

Hollow Carbon Microspheres with Tunable Mesoporous Shell and Their Ultrawide-band Microwave Absorption Performance

中空多孔结构有助于延长电磁波在吸波介质材料内部的传播距离,诱导产生多重反射和散射,增强对电磁能量的衰减损耗。在本项工作中,通过原位聚合—高温碳化—碱液蚀刻工艺设计构筑具有可设计介孔外壳的碳中空微球。通过扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、X射线衍射(XRD)及拉曼光谱(Raman spectrum)等测试手段分别对其形貌结构、元素组成、晶体结构进行表征。研究结果表明,高温碳化温度对材料样品碳结构的缺陷含量及石墨化程度具有重要影响,进而影响材料的介电性能及其微波吸收性能。800℃碳化得到的中空碳微球具有最优异的微波吸收性能,在匹配厚度为3.0mm时,最小反射损耗值(RLmin)可以达到-42.26dB,对应的有效吸收频带(EAB)达到5.12GHz;当匹配厚度为2.3mm时,中空碳微球的最宽有效吸收频带达到7.8GHz,远优于其他碳基吸波材料。对其进行吸波机理分析得知,其优异的吸波性能主要与其增强的阻抗匹配性能和衰减系数及特殊中空结构诱导的多重散射和反射相关。

The hollow porous structure helps to prolong the propagation path of electromagnetic waves inside the material,causing multiple reflections and scattering,and thus losing electromagnetic energy.In this work,carbon hollow microspheres with designable mesoporous shells were constructed by in-situ polymerization-carbonization-etching process.The morphology,elemental composition and crystal structure were characterized by SEM,XPS,XRD and Raman spectroscopy.The results showed that the calcination temperature had an important effect on the carbon structure defects and the degree of graphitization,which in turn affected the microwave absorption property.The hollow carbon microspheres obtained by calcination at 800℃displayed the best microwave absorption performance.When the matching thickness was 3.0mm,the minimum reflection loss value reached-42.26 dB,and the corresponding effective absorption frequency band was 5.12 GHz.Importantly,when the matching thickness was 2.3 mm,the widest effective absorption band of hollow carbon microspheres reached 7.8 GHz,which was much better than other carbon-based absorbing materials.According to the analysis of absorbing mechanism,the excellent absorbing performance was mainly related to the enhanced impedance matching performance,attenuation coefficient and multiple scattering and refraction induced by special hollow structure.