【作者】 李琪；

【导师】 廖庆亮；

【作者基本信息】 北京科技大学 ， 材料科学与工程， 2023， 博士

【摘要】 随着信息技术和电子工业的发展,在高精尖武器装备、智能电子设备和民用物联网等需求的牵引下,电磁波吸收材料发挥着重要作用。开发高性能电磁波吸收材料成为军事装备升级和民用电磁安全中亟待解决的战略挑战。传统的电磁波吸收材料存在着衰减机制单一和阻抗匹配性差等问题,难以满足实际应用的要求。针对电磁波吸收材料发展的瓶颈问题,本论文围绕吸波材料的设计、开发及性能全面提升,开展了低维金属硫化物吸波材料的设计制备与性能调控研究。采用结构与界面、维度、缺陷以及熵等调控策略,控制合成了低维金属硫化物异质结构。通过调控组份、添加量和厚度,厘清了电磁参数、阻抗匹配和损耗系数对电磁响应的影响规律,优化反射损耗和有效吸波频宽。揭示了低维金属硫化物吸波材料的电磁损耗机制,仿真了其实际远场电磁响应,为高性能吸波材料的设计开发提供了理论基础和数据支撑。发展了结构设计和界面工程协同调控策略,构筑了 VS4纳米棒/rGO异质结构吸波材料,系统研究了电磁响应特性和反射损耗性能。通过控制VS4纳米棒在rGO的锚定量,精准调控VS4/rGO异质结构的微结构和异质界面,优化阻抗匹配和损耗系数分别达到0.98和187,对应的反射损耗在1.5 mm时能达到-43.5 dB;有效吸波频宽在1.4 mm时达到了 4.8 GHz,得到了超薄电磁波吸收材料。理论计算结合实验解密了异质界面在电磁响应和极化损耗中的作用机制,揭示了 VS4纳米棒/rGO异质结构材料的电磁损耗机理。CST电磁仿真模拟异质结构涂层的实际远场电磁响应,当电磁波在14 GHz且0°垂直入射时,1.5 mm厚异质结构涂层对完美导电体(Perfect Electric Conductor,PEC)的雷达散射截面面积(Radar Cross Section,RCS)衰减值达38.4 dB·m2。发展了跨维度异质结构设计策略,控制聚吡咯(Polypyrrole,PPy)纳米管、MoS2纳米片和氮掺杂石墨烯(N-dopped Graphene,NG)的合成自组装,构筑了 MoS2纳米片@PPy/NG异质结构材料。通过集成各维度材料的特有优势,包括PPy纳米管的各向异性和管状结构、MoS2纳米片的平面反射和面内电子转移以及1T/2H异质相界面的特性、NG的微褶皱和比表面积大等优势,调控MoS2纳米片@PPy/NG异质结构的电磁参数、阻抗匹配与损耗系数。MoS2纳米片@PPy/NG异质结构的有效吸波频宽在2.4 mm时达到6 GHz,反射损耗峰值接近-20 dB。MoS2纳米片@PPy/NG异质结构实现了 50%的减重,满足了电磁波吸收材料的轻量化要求。揭示了跨维度异质结构材料的电磁损耗机理,总结了各维度的电磁响应与损耗特性。CST电磁仿真模拟证明,当频率为14 GHz且0°入射时,2.4 mm厚的MoS2纳米片@PPy/NG涂层对PEC的RCS衰减值达14.3 dB·m2。为弥补偶极极化和界面极化损耗对电磁波损耗的不足,开展了多重极化损耗耦合增强策略研究。通过自分散溶剂热法成功构筑了 rGO表面附着Bi2S3纳米棒的Bi2S3纳米棒/rGO异质结构,研究了 Bi2S3纳米棒与rGO比例以及异质结构材料添加量对电磁参数和反射损耗的影响规律,调控Bi2S3纳米棒/rGO异质结构的阻抗匹配和损耗系数分别达到0.99和110,对应的反射损耗在8.35 GHz和3.0 mm时达到超高的-76.25 dB,有效吸波频宽在2.0 mm时取得6.6GHz,得到了具有超强反射损耗的电磁波吸收材料。异质结构的偶极极化、各向异性极化以及界面极化产生的耦合极化损耗增强了电磁波的介电损耗性能。CST电磁仿真模拟证明,电磁波频率为11 GHz且异质结构涂层厚度为1.5 mm时,其RCS值在-90°<theta<90°内小于-10 dB·m2。电磁波0°角垂直入射异质结构涂层对PEC的RCS衰减值达30.79 dB·m2。开展了高熵金属硫化物异质结构材料的电磁波吸收性能研究,通过甘油酸盐前驱体低耗能热硫化法成功制备了蛋黄壳微球结构的高熵(FeNiCoCuMn)S2纳米颗粒金属硫化物,并与 rGO 复合构筑了(FeNiCoCuMn)S2纳米颗粒/rGO异质结构材料,充分利用了异质结构材料的高熵效应和微空间效应获得了优异的电磁波损耗性能。(FeNiCoCuMn)S2纳米颗粒/rGO异质结构的反射损耗峰值在1.4 mm时达到-22 dB,有效吸波频宽在厚度1.6 mm时达到5.6GHz,实现了对入射电磁波的宽频吸收。当厚度2.2 mm时,有效吸波频宽可覆盖8.7～12.1 GHz,基本实现了对X波段的有效吸收。CST电磁仿真模拟证明,频率为13 GHz的电磁波且0°垂直入射覆盖有1.7 mm厚异质结构涂层的PEC,对PEC的RCS衰减值可达24.6 dB·m2,展现出优异的实际远场电磁响应特性。更多还原

【Abstract】 The rapid development of information technologies and electronics has increased the demand for microwave absorption materials in various applications,including military equipment,electronic devices,and IoT systems.To address this challenge,this paper designs and develops enhanced microwave absorption materials.The focus is on the preparation and application research of highperformance low-dimensional metal sulfides(MSs)microwave absorption materials.The study involves synthesizing unique heterostructures of lowdimensional MSs and optimizing their electromagnetic parameters,impedance matching,and attenuation constant to improve reflection loss(RL)intensity and effective absorption bandwidth(EAB).Experiments and theoretical calculations reveal the microelectromagnetic response and attenuation mechanism of lowdimensional MSs heterostructures.The study also uses CST Studio simulation to provide a theoretical basis and data support for designing high-performance microwave absorption materials.In summary,this study meets the requirement for efficient and versatile microwave absorption materials and provides valuable insights into their design and exploitation.A structural design and interface engineering strategy was proposed for the VS4 nanorod/rGO heterostructure,revaling its electromagnetic response characteristics and attenaution performance.By controlling the VS4 nanorod anchoring amount on rGO,the microstructure and heterointerface of VS4/rGO heterostructure were regulated to optimize impedance matching and attenuation constant,achieving 0.98 and 187,respectively.At an ultrathin thickness of 1.5 mm,the RL was-43.5 dB.The EAB of 4.8 GHz was achieved at 1.4 mm.The role of heterointerface in electromagnetic response and polarization loss was decrypted,revealing the microwave loss mechanism.The 2VS4/rGO40-30%coating with a thickness of 1.5 mm had a radar cross section(RCS)reduction value of 38.4 dB·m2 when the microwave was incident at 0° and 14 GHz,according to CST electromagnetic simulation.Inter-dimensional heterostructure design strategy was proposed,and a MoS2 nanosheet@polypyrrole(PPy)/NG heterostructure was constructed by selectively synthesizing MoS2 nanosheets,polypyrrole(PPy)nanotubes,and nitrogen-doped graphene(NG).By integrating the unique advantages of multidimensional materials,including the anisotropy and tubular structure of PPy nanotubes,the flat reflection and in-plane electron transfer of 2D MoS2 nanosheets,the characteristics of 1T/2H hetero-phase interfaces,and the micro-wrinkles and large specific surface area of 3D NG,the electromagnetic parameters,impedance matching,and RL of MoS2 nanosheet@PPy/NG heterostructures were regulated to achieve a RL of-35.6 dB at a thickness of 1.5 mm and a frequency of 9.9 GHz.The electromagnetic response mechanism and loss mechanism of MoS2 nanosheet@PPy/NG heterostructures were analyzed by experiments and theoretical calculations.High-quality Bi2S3 nanorod/rGO heterostructure was successfully prepared via a solvothermal method.The influence of the interface and the ratio of Bi2S3 nanorods to rGO on electromagnetic response and parameters were studied.The impedance matching and RL were regulated,optimizing the strong electromagnetic response.With the 8.35 GHz and 3.0 mm thickness,the RL peak reached-76.25 dB,achieving 99.99%absorption for incident microwaves.The EAB covered 11.4-18.0 GHz at 2.0 mm thickness.The RCS value was less than-10 dB·m2 for90°<theta<90° at 11 GHz and 1.5 mm,and RCS reduction value was 30.79 dB·m2 when the microwave was incident at 0°.High-entropy low-dimensional MSs were employed for the first time in the design of microwave absorption materials.(FeNiCoCuMn)S2 nanocrystalline eggshell microsphere MSs were prepared through a glycerol precursor thermal sulfidation method.To improve their electromagnetic response and attenuation characteristics,rGO-coated heterostructure of high-entropy MSs microspheres was constructed.This design strategies achieved efficient microwave absorption performance through entropy regulation and microspace structure design.The RL peak of the heterostructure reached-22 dB at 1.4 mm,and the EAB reached 5.6 GHz at 1.6 mm.At a thickness of 2.2 mm,the EAB covered 8.7～12.1 GHz,achieving effective absorption in the X-band.The RCS value was-9.58 dB·m2 at 13 GHz and a thickness of 1.7 mm,and the RCS reduction value reached 24.6 dB·m2 when the microwave was incident at 0°,according to CST electromagnetic simulation.更多还原