【作者】 刘琳琳；

【导师】 王世良；

【作者基本信息】 中南大学 ， 工程硕士（专业学位）， 2022， 硕士

【摘要】 关于碳(C)基复合材料的微波吸波特性的研究已持续了半个多世纪并已获得了一些实际应用,然而硬碳(HC)基复合材料的微波吸波性能却鲜少研究。本文通过酚醛树脂和氧化锌(Zn O)纳米颗粒的混合物的热解反应,合成出了一种由直径约25 nm的Zn O纳米颗粒和厚度约100 nm的层状硬碳(LHC)镶嵌而成的新型HC基复合纳米材料,层状硬碳@Zn O纳米颗粒(LHC@Zn ONPs),然后通过高温真空退火方法将所合成的LHC@Zn ONPs中的纳米颗粒蒸发去除,获得多孔层状硬碳(PLHC)材料,最后,采用扫描电子显微镜、X射线衍射仪、拉曼光谱仪、透射电子显微镜、X射线光电子能谱、傅里叶变换红外光谱仪和矢量网络分析仪等对所合成的复合材料的形貌、元素成分、结构和吸波性能等进行了系统的表征,并讨论了其“结构-吸波性能”关系。对比测试和分析结果表明:(1)当LHC@Zn ONPs与石蜡的填料比为1:1.5时,在3.3 mm的吸收厚度下可获得的最佳反射损耗值达到了-38 d B,对应的有效吸收带宽为5.7 GHz。LHC@Zn ONPs的优异吸波性能可归因于Zn O/HC和LHC/LHC界面的界面极化,以及由HC层中的缺陷、纳米孔和残留有机官能团引起的增强的偶极极化等;(2)当PLHC与石蜡的填料比为1:5时,最佳反射损耗值在2.8 mm的吸收厚度下达到-42 d B,有效吸收带宽在3.7mm的吸收厚度下达到6.6 GHz。PLHC的优异吸波性能是因为纳米孔增加了入射微波在样品中的反射次数,增大了能量的损耗;同时,HC中存在大量的缺陷也增加了样品的极化损耗。本文的研究结果表明HC基复合材料具有优异的吸波性能,可为高性能吸波材料的合理设计提供新的研究思路。图31幅,表3个,参考文献161篇更多还原

【Abstract】 Research on the wave-absorption properties of carbon(C)matrix composites has been going on for more than half a century and has achieved some practical applications.However,as an exception among Cbased materials,the microwave-absorption properties of hard carbon(HC)-based nanocomposites have been rarely studied and thus currently remain unknown.In this research work,Hard carbon@Zn O nanoparticle layers(LHC@Zn ONPs)were synthesized by pyrolysis of a mixture of Phenol formaldehyde resin and zinc oxide(Zn O)nanoparticles which is a novel HC-based composite nano-material essentially composed of Zn O nanoparticles with a diameter of approximately 25 nm and layered hard carbon(LHC)with a thickness of 100 nm.Then the nanoparticles in the synthesized LHC@Zn ONPs nano-composite were evaporated and removed by high temperature vacuum annealing method to obtain porous layered hard carbon(PLHC)materials.Finally,the morphology,elemental composition,structure and wave-absorbing properties of the synthesized nanocomposites were systematically studied and characterized by various techniques like scanning electron microscope,X-ray diffractometer,Raman spectrometer,transmission electron microscope,X-ray photoelectron spectroscopy,Fourier transform infrared spectrometer and vector network analyzer,etc.,with the aim to describe their "structureabsorbing performance" relationship.The results show that :(1)when the filling ratio of LHC@Zn ONPs to paraffin wax is 1:1.5,the best reflection loss is-38 d B at 3.3 mm absorption thickness,and the corresponding effective absorption bandwidth is 5.7 GHz.The excellent wave-absorbing properties of LHC@Zn ONPs can be attributed to the interfacial polarization at the Zn O/HC and LHC/LHC interfaces,as well as the enhanced dipole polarization caused by the defects,nanopores,and residual organic functional groups in the HC layer,etc.(2)When the filler ratio of PLHC and paraffin is 1:5,the optimal reflection loss value reaches-42 d B at the absorption thickness of 2.8 mm,and the effective absorption bandwidth reaches 6.6 GHz at the absorption thickness of 3.7 mm.The excellent absorbing performance of PLHC corresponds due to the nanoporous nature which subsequently increase the number of reflections of the incident microwaves in the sample,which enhances the chances of energy loss.At the same time,the existence of a large number of defects in the HC also increases the polarization loss of the sample.The research results described in this paper shows that HC-based nanocomposites have excellent microwave absorbing properties,which can provide new research methods for the rational design of high-performance microwave absorbing materials.更多还原