轻质磁性炭气凝胶的制备及电磁吸波性能研究  

Preparation and Electromagnetic Wave Absorbing Properties of Light Magnetic Carbon Aerogel

作　　者：叶正伟 赵奇志 王克军 李孝琼 杨健健 YE Zheng-wei;ZHAO Qi-zhi;WANG Ke-jun;LI Xiao-qiong;YANG Jian-jian(Chemical Defense Research Institute,Academy of Military Sciences,Wuhan 430000,China)

机构地区：[1]军事科学院防化研究院,武汉430000

出　　处：《表面技术》2023年第8期397-405,共9页Surface Technology

基　　金：装备发展基金。

摘　　要：目的提高炭气凝胶材料电磁吸波性能。方法以氢氧化钠或氨水为共沉淀剂制备不同尺寸的Fe_(3)O_(4)颗粒,并加入间苯二酚-甲醛溶液的预聚物中,充分搅拌后快速凝胶,经老化、超临界干燥、碳化等工艺制备Fe_(3)O_(4)/炭气凝胶复合材料。利用SEM、TEM、激光粒度分析仪、比表面及微孔分析仪、振动样品磁强计对Fe_(3)O_(4)及复合材料的微观结构和静磁性能进行表征,并对复合材料的吸波性能进行分析。结果Fe_(3)O_(4)/炭气凝胶复合材料具有丰富的三维网络结构,Fe_(3)O_(4)颗粒在炭气凝胶中呈离散性分布。Fe_(3)O_(4)颗粒粒径越小,Fe_(3)O_(4)/CA的饱和磁化强度越大,75 nm-Fe_(3)O_(4)/CA的饱和磁化强度最大,达到29.26 emu·g^(-1);当Fe_(3)O_(4)粒径为75 nm时,复合材料在厚度为2.1 mm时的最小反射损耗值可达-52.43 dB;当Fe_(3)O_(4)粒径为120 nm时,复合材料在厚度为2.5 mm时的有效吸收带宽高达6.98 GHz。结论Fe_(3)O_(4)纳米颗粒粒径对复合材料介电损耗能力和阻抗匹配有显著影响,进而影响复合材料的吸波性能。大粒径的Fe_(3)O_(4)颗粒会破坏炭气凝胶的三维导电网络结构,从而降低复合材料的介电损耗能力。小粒径的Fe_(3)O_(4)颗粒可有效改善复合材料的阻抗匹配性能。With the rapid spread of wireless communication devices using electromagnetic waves in the range around GHz,several problems such as electromagnetic interference and information leakage have emerged and need to be solved.Microwave absorption materials can absorb electromagnetic waves effectively and convert electromagnetic energy into thermal energy,thus are highly demanded to eliminate adverse electromagnetic waves effectively in electronic safety,and national defense security.Porous carbon materials are always employed to absorb microwave energy due to the very large surface area and great potential for further functionalization.In this paper,ferrite/carbon aerogel composites were fabricated to endow the carbon aerogel magnetic property and also lower density of composites.First,Fe_(3)O_(4)particles of different sizes were prepared by a simple co-precipitation(using sodium hydroxide or ammonia as co-precipitator)through controlling the Fe ions concentration of the reaction system.Then the aqueous solution of Fe_(3)O_(4)modified by CTAB was prepared and added to the resorcinolformaldehyde sol.After sufficient mixing,the solution was left to gel by elevating the temperature and supercritical drying subsequently.The final magnetic carbon aerogel composites were obtained by pyrolysis of the organic polymeric aerogel at 690℃.SEM(FEI Company Sirion200)and TEM(Japan Electronics Corporation JEM-1400Plus)were used to characterize the Fe_(3)O_(4)particle size and microstructure of the composites.A laser particle size analyzer(Malvern Company Zetasizer Nano ZSP)was used to characterize the particle size and distribution of the Fe_(3)O_(4)particles.The surface area and pore size of the magnetic carbon aerogels were characterized by a specific surface and micropore analyzer(BSD-PM).The static magnetic properties of the materials were characterized by a vibrating sample magnetometer(Lake Shore model 7404G).The complex permeability and permittivity of materials were measured with a N5230A vector network analyzer by coaxial

关 键 词：炭气凝胶 四氧化三铁 粒径 电磁吸波材料 阻抗匹配 

分 类 号：TG147[一般工业技术—材料科学与工程]