【作者】 王蕾；

【导师】 陆海鹏；

【作者基本信息】 电子科技大学 ， 电子科学与技术， 2023， 硕士

【摘要】 轻质高效的吸波结构材料在国民经济各个领域和国防建设方面都有着重大意义。目前,轻质高效吸波结构材料设计的首要要求是吸收剂的选择。碳材料具有高的电导率、大的比表面积以及极低的密度,使其成为电磁波吸收领域最具潜力的吸收剂之一。但碳材料的高电导会使得材料电磁参数失衡,从而导致电磁波入射界面与自由空间的阻抗不匹配,电磁波将会在入射表面被全反射。因此,通过对碳基吸波材料进行改性来提高其阻抗匹配特性很有必要。本文首先以导电炭黑（CB）、碳纳米管（CNT）、还原氧化石墨烯（rGO）作为介电型损耗吸收剂,分析不同形貌特征的碳材料的电磁参数特性及吸波机理;在此基础上,选用rGO作为改性对象,制备了两种石墨烯基复合吸收剂,分析其在0.5-18GHz的电磁性能和吸波性能。并采用SEM、TEM、XRD、Raman、XPS、TGA、VNA等表征手段对复合吸收剂的微观形貌、物相组成、化学态、热稳定性、电磁参数等进行研究,并分析吸波机理。具体研究内容如下:（1）从物相组成和微观结构出发,研究了三种碳基吸收剂在不同质量分数下的电磁性能,并分析了吸波损耗机理。研究表明:rGO具有更加丰富的缺陷特征,介电损耗高,使得rGO相对于CB和CNT而言,更适合作为改性吸收剂。（2）采用水热法制备了石墨烯-镍锌铁氧体（rGO-NZF）复合吸收剂,研究复合吸收剂形貌结构以及电磁性能随组分比例的变化情况,并分析吸波机理。研究表明:复合吸收剂的吸波性能随着rGO含量的不同存在较大的变化。10rGO-NZF样品表现出优异的吸波性能,在厚度为2.5 mm时,频率为10.8 GHz处达到最小反射损耗-41.3 d B且厚度在2 mm时有效带宽可达5.68 GHz（11.7-17.38 GHz）。（3）采用一步法制备了石墨烯-镍锌铁氧体@二氧化硅复合吸收剂（rGO-NZF@Si O₂）,研究包覆结构对复合吸收剂微观形貌、物相结构、热稳定性和吸波性能的影响。研究表明:核壳结构的NZF@Si O₂纳米颗粒修饰多层rGO而形成了三维异质结构,缓解了rGO引起的电磁波强反射,提升了复合吸收剂的阻抗匹配特性。通过NZF@Si O₂和rGO的磁介协同效应,在2.9 mm的厚度下,频率为10.7GHz处达到最小反射损耗-49 d B,且在厚度为2.2 mm处有效吸收带宽达到5.7 GHz（12.3-18 GHz）。并且由于Si O₂耐温层的引入可以有效降低样品的分解速率,从而延长了样品的热稳定时间,扩大了石墨烯基复合吸收剂的应用领域。更多还原

【Abstract】 Light and efficient absorbing structural materials are of great significance in various fields of national economy and national defense construction.At present,the selection of absorbent is the primary requirement of the design of lightweight and efficient absorbing structural materials.Carbon materials have high conductivity,large specific surface area and extremely low density,making it one of the most potential absorbers in the field of electromagnetic wave absorption.However,the high conductivity of carbon materials will make the electromagnetic parameters of the material unbalance,resulting in the mismatch between the electromagnetic wave incident interface and the impedance of free space,and the electromagnetic wave will be fully reflected at the incident surface.Therefore,it is necessary to improve the impedance matching characteristics of carbon-based absorbing materials by modifying them.Firstly,using conductive carbon black（CB）,carbon nanotubes（CNT）and reduced graphene oxide（rGO）as dielectric loss absorbers,the electromagnetic parameters and absorbing mechanism of carbon materials with different morphological characteristics were analyzed.On this basis,rGO was selected as the modified object to prepare two kinds of graphene-based composite absorbers,and their electromagnetic and wave-absorbing properties at 0.5-18 GHz were analyzed.The microstructure,phase composition,chemical state,thermal stability and electromagnetic parameters of the composite absorbent were studied by means of SEM,TEM,XRD,Raman,XPS,TGA and VNA,and the absorbing mechanism was analyzed.Specific research contents are as follows:（1）Based on the phase composition and microstructure,the electromagnetic properties of three carbon based absorbers with different mass fractions were studied,and the absorbing loss mechanism was analyzed.The results show that rGO has more abundant defect characteristics and high dielectric loss,which makes rGO more suitable as a modified absorber compared with CB and CNT.（2）Reduced graphene oxide-NiZn ferrite（rGO-NZF）composite absorbent was prepared by hydrothermal method.The morphology,structure and electromagnetic properties of the composite absorbent varied with the proportion of components,and the absorbing mechanism was analyzed.The results show that the absorption properties of the composite absorbers vary greatly with the content of rGO.The 10rGO-NZF sample showed excellent absorbing performance,and the minimum reflection loss was-41.3d B at the frequency of 10.8 GHz when the thickness was 2.5 mm,and the effective bandwidth was 5.68 GHz（11.7-17.38 GHz）when the thickness was 2 mm.（3）Reduced graphene oxide-NiZn ferrite@Si O₂ composite absorbent（rGO-NZF@Si O₂）was prepared by a one-pot method.The effects of coating structure on the microstructure,phase structure,thermal stability and wave absorption performance of the composite absorbent were investigated.The results showed that the core-shell NZF@Si O₂ nanoparticles modified the multilayer rGO to form a three-dimensional heterogeneous structure,which alleviated the strong reflection of electromagnetic wave caused by rGO and improved the impedance matching characteristics of the composite absorber.Through the synergistic interaction of NZF@Si O₂ and rGO,the minimum reflection loss of-49 d B is achieved at a frequency of 10.7 GHz at a thickness of 2.9 mm,and the effective absorption bandwidth reaches 5.7 GHz（12.3-18 GHz）at a thickness of2.2 mm.Moreover,the introduction of Si O₂ temperature resistant layer can effectively reduce the decomposition rate of the sample,thus prolongating the thermal stability time of the sample and expanding the application field of graphene-based composite absorbent.更多还原