碳纳米管材料低频电磁参数及吸波产热特性

微波的热利用技术促进了吸波材料的应用研究。碳纳米管(CNTs)是近年来新兴的强吸波材料,具有密度小、比表面积大、量子尺寸效应的特点。对碳纳米管吸波材料的复介电常数和复磁导率随碳纳米管含量的变化进行探究。在此基础上,以石蜡油为蓄热介质探究了碳纳米管材料在微波辐照下吸波产热特性。同轴传输法适用于小型样品的测量,具有误差小的优点,故采用此种方法作为测量电磁参数手段。对碳纳米管电磁参数测量实验结果表明,碳纳米管吸波材料在低频下对于微波能的损耗兼具电损耗和磁损耗。对碳纳米管吸波产热特性实验结果表明,碳纳米管是一种强吸波材料。     

吸波材料的微波损耗机理及结构设计

就吸波材料与电磁波的相互作用及其损耗机理进行了阐述。通过对吸波材料与电磁波相互作用的研究和不同类型吸波材料微波损耗机理的详细探讨，对研制高宽频、质轻、红外微波隐身兼容复合型吸波材料进行了展望，并提出了材料结构设计的思路。     

硅基橡胶聚合物基复合吸波材料5G射频天线干扰抑制研究

5G网络建设下电磁环境日益复杂,电磁干扰现象也逐渐严重。分析了5G MU-MIMO大规模天线阵列的应用场景和特点,并对吸波材料的电物理特性进行基础探究。采用甲基硅橡胶材料作为吸波体单元结构原材料,以适应5G天线室外使用要求。设定了技术路线和吸波体材料、形状、尺寸等参数,并设置波导实验装置,对散射参数(Scattering Parameters)进行测量,经高频电磁仿真软件(CST)仿真,验证实验结论。在3.50 GHz和4.86 GHz这2个频率点,入射波的吸收率能够超过90%,可较好实现硅基橡胶聚合物基复合吸波材料对5G射频天线干扰的抑制作用。     

吸波材料的电磁损耗及其制备的探讨

本文通过对吸波材的电磁损耗机理的探讨,揭示了影响材料吸波性能的主要电磁参数间的制约匹配关系,讨论介绍了吸波材料的设计要求及制备时应注意的一个物理条件.     

微波与碳基催化剂协同促进果糖制5-羟甲基糠醛

生物质转化为高附加值的化学品是替代石化产品的有效途径,微波与催化剂的协同作用有助于提升糖类的转化效率。碳材料具有良好的化学稳定性和介电性,是微波反应过程中理想的催化剂载体和吸波剂。为了探究碳基催化剂对微波场的响应能力,本文以4种碳材料为载体应用于果糖转化过程,包括碳纳米管（CNT）、碳纳米纤维（CNF）、炭黑（CB）和活性炭（AC）。以果糖转化率和5-羟甲基糠醛（5-HMF）收率为评价指标,对比不同催化剂在常规和微波加热条件下的催化性能,探究微波与不同载体的耦合作用对反应的强化效果。在微波场中测量不同碳材料悬浮液的温度曲线,评价碳基催化剂在微波场中的加热能力。通过表征样品结构和介电参数,解释载体与微波间耦合作用差异的原因。结果表明,碳基催化剂的微波诱导热效应可以有效提升反应转化率和收率,拥有高损耗角正切值和电导率的催化剂把微波能转化为热量的能力较强,更有助于将微波能量传递至反应表面。高比表面积、高长径比、低密度和高石墨化度的碳基催化剂也有利于产生微波热效应。另外,由于显著的微波热效应,碳纳米管基催化剂CNT-SA在4类催化剂中催化性能最优,以110℃微波辐射10min,5-HMF收率可达96.30%,且催化剂具有良好的循环使用性能。     

微波介质复介电常数的带状线法测量

采用工作波型为TEM的带状线谐振方法 ,对研制的PTFE/陶瓷 /微纤维为主要组成的多元复合微波介质系列基板的复介电常数进行了测量 ,结果表明 :对薄片状大面积基板采用带状线方法测试可以获得高精度且一致性好的数据。对微波频率下相对介电常数与介质损耗的机制及带状线测试产生的误差因素进行了探讨分析     

自然气象条件下某型吸波涂料静态吸波能力变化模型建立

研究了自然气象条件下单层碳纤维吸波涂料的静态吸波性能随时问变化的规律。通过人工加速老化试验模拟自然气象分周期作用于吸波材料试样，然后测量其电磁参数与反射率，并对实验数据进行处理，结合由电磁参数计算反射率模型的理论推导，最终建立了试样的反射率随时间变化模型，并依此预测此涂料的使用寿命，为确定其在隐身飞行器上的使用与维护时限提供依据。     

碳基铁氧体复合吸波材料的研究进展

近年来,电磁污染带来的伤害使人们越来越多的关注到这位"隐形杀手"。人们致力于研究新型的复合吸波材料,特别是将具有导电损耗型吸波材料和磁损耗型吸波材料进行复合,制备出一系列新型复合材料。本文对不同种类吸波材料进行了详细的介绍,并且研究了炭系吸波材料的研究进展。     

碳纳米管在聚合物基吸波复合材料中的应用

碳纳米管作为一种新型电磁吸波剂,因其独特的物理和化学性能引起了人们极大的关注。本文简述了碳纳米管的吸波机理及吸波性能的表征,重点介绍了碳纳米管在聚合物吸波复合材料中的应用,如碳纳米管/树脂基复合材料、碳纳米管/导电高聚物复合材料、碳纳米管/橡胶基复合材料,最后展望了吸波材料的发展方向。     

H_(01n)模谐振腔测量介质复介电常数

采用Ｈ０１ｎ模螺旋线圆柱谐振腔对研制的ＰＴＦＥ复合精细陶瓷微波介质材料的复介电常数进行了测量，获得了数据比较一致的满意结果。对微波频率下测试试样所引起的相对介电常数和损耗的误差因素进行了解释。     

Development of Low Density,Heat Resistant and Broadband Microwave Absorbing Materials (MAMs) for Stealth Applications

The development of low density and broadband microwave absorbers are the need of the hour to cater for the needs of all military platforms for stealth technology. The low density and broadband properties can be inculcated in microwave absorbers using dielectric lossy materials (e.g. carbon fibres, carbon nanotubes, carbon black, fullerene, graphite, graphene and silicon carbide fibre). Therefore, we designed low density and heat resistant microwave absorbing materials (MAMs) using a novel approach of ceramic fibre board manufacturing technology. The microwave absorbing composites were prepared with varying percentage of milled carbon fibres, discontinuous aluminosilicate fibres and silicone resin as the matrix. The physico-mechanical properties of microwave absorbing composites were determined. Reflection loss of microwave absorbing composites was measured in the frequency range 2–18 GHz by unique single horn interferometry technique. The electromagnetic properties were measured in X-band using free space measurement system. Based on these properties the effect of thickness on the microwave absorbing properties in X-band was simulated The effect of weight % variation of milled carbon fibres on the microwave absorbing properties of composites have been studied in the frequency range 2–18 GHz.     

Recent advances in carbon nanotubes-based microwave absorbing composites

With the blossom of information industry, electromagnetic wave technology shows increasingly potential in many fields. Nevertheless, the trouble caused by electromagnetic waves has also drawn extensive attention. For instance, electromagnetic pollution can threaten information safety in vital fields and the normal function of delicate electronic devices. Consequently, electromagnetic pollution and interference become an urgent issue that needs to be addressed. Carbon nanotubes (CNTs) have become a potential candidate to deal with these problems due to many advantages, such as high dielectric loss, remarkable thermodynamic stability, and low density. With the appearance of climbing demands, however, the carbon nanotubes combining various composites have shown greater prospects than the single CNTs in microwave absorbing materials. In this short review, recent advances in CNTs-based microwave absorbing materials were comprehensively discussed. Typically, we introduced the electromagnetic wave absorption mechanism of CNTs-based microwave absorbing materials and generalized the development of CNTs-based microwave absorbers, including CNTs-based magnetic metal composites, CNTs-based ferrite composites, and CNTs-based polymer composites. Ultimately, the growing trend and bottleneck of CNTs-based composites for microwave absorption were analyzed to provide some available ideas to more scientific workers.     

活化碳纳米管的孔结构及微波吸收性能的研究

以KOH为活化剂对碳纳米管进行活化处理，将碳纳米管的比表面积从24．5m^2/g提高到360．1m^2／g，孔容从0．051cc／g提高到0．572cc/g。对碳纳米管的微波吸收性能进行测试，研究结果发现，未活化碳纳米管在9．91～14．16GHz范围内对电磁波的反射率低于-5dB，最大衰减峰值为8．57dB；活化碳纳米管在5．37～18GHz范围内对电磁波的反射率低于一5dB，在6．48～10．88GHz范围内对电磁波的反射率低于一10dB，最大的衰减峰值达到22．58dB。通过比较得出，活化能够有效地提高碳纳米管的微波吸收性能。产生的原因是由于活化碳纳米管具有大的比表面积和丰富的孔结构，电磁波在这些孔结构中不断的被反射、漫射而逐渐衰减。     

Morphology and microwave absorption of carbon nanotube/bismaleimide foams

Proper dispersion should be guaranteed when using carbon nanotubes (CNTs) as effective absorbents. Physical dispersion methods, such as mechanical mixing, ball milling, and calendering process (three‐roll milling), were adopted to disperse CNTs in the bismaleimide matrix to foam. The effects of the dispersion methods on viscosity, bubble morphology, and microwave‐absorbing properties at 12–18 GHz were studied. The results indicated that, three‐roll milling can more efficiently separate individual CNTs from the agglomerates compared with the other two methods. This method exhibited the highest viscosity, the most irregular cell shape, and the best microwave‐absorbing property. The effects of CNT concentration and foam thickness on the microwave‐absorbing properties were also studied. The reflectivity decreased and the position of the reflectivity peak moved to a lower value with increase in CNT concentration and foam thickness. The foam with 30 mm thickness achieved a reflection loss below ?8 dB over 3.0 GHz in the range of 13.5–16.5 GHz. The minimum value is ?14.2 dB at 14.6 GHz. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40233.     

新型肿瘤热疗用温敏凝胶的制备与表征

采用化学共沉淀结合水热处理的方法,控制一定的反应条件,制备了碳纳米管/四氧化三铁(CNTs/Fe3O4)热种子材料,然后以壳聚糖温敏凝胶为载体,将CNTs/Fe3O4复合材料分散到凝胶中,制备出微波靶向热疗用碳纳米管-四氧化三铁-壳聚糖温敏凝胶。碳纳米管复合热种子材料在凝胶体系中分布均匀,与载体不发生化学反应,25 W下辐照10 min,当CNTs/Fe3O4复合材料的质量浓度为20 mg/mL时,体系温度在初始温度基础上升高了38.7℃,在微波场中具有良好的产热能力,可以满足微波热疗的要求。     

Preparation of high-performance carbon nanotube/polyamide composite materials by elastic high-shear kneading and improvement of properties by induction heating treatment

Polyamide 66 (PA66) nanocomposites were prepared by compounding carbon nanotubes (CNTs) using an elastic high-shear kneading method, and the mechanism to understand their excellent properties was verified. In addition, we developed a microwave heat treatment that increases toughness quickly and at low cost. By combining 6.6 vol% or more of CNTs, PA66 with improved mechanical properties, such as higher elastic modulus and yield strength, was achieved, making it possible to obtain a composite having excellent high-temperature characteristics that does not melt even at a temperature above the melting point. These effects appeared to be due to defibration of CNT aggregates and isolation and dispersion in PA66. A lamellar crystal of PA66 grows around the CNT, forming an interphase. The higher performance appeared to be attributable to a continuous three-dimensional structure in which CNTs are bound via the interphase, and the improvement of the elastic modulus of the composite material was tentatively ascribed to a Halpin-Tsai model in which the size of the unit cell of the three-dimensional structure is introduced. The resulting CNT/PA66 composite materials are superior not only in performance but also in price.     

纳米碳管复合固态光限幅材料的制备及性能研究

采用溶胶-凝胶法成功地制备了二氧化硅凝胶玻璃基质纳米碳管掺杂复合固态光限幅材料，分别对纳米碳管在溶液和固态基质中的光限幅特性进行了测试。结果表明其在固态基质中具有更好的光限括效应，为实现纳米碳管在光限幅应用领域的材料化进而器件化奠定了理论和实验基础。     

结构型碳纤维吸波复合材料的研究及应用

结构型碳纤维吸波复合材料结合了复合材料轻质高强的结构优势和吸波特性,是雷达隐身材料的重要发展方向。本文主要从异型截面碳纤维、手性碳纤维和碳纳米管等新型吸波碳纤维增强体以及夹芯结构、点阵结构形式等方面总结了结构型碳纤维吸波复合材料国内外的最新研究和应用进展,并指出了未来发展方向。     

Microwave responsive epoxy nanocomposites reinforced by carbon nanomaterials of different dimensions

This study fabricated nanocomposites consisting of epoxy‐based shape memory polymer (ESMP) matrix and carbon nanofillers. The nanofillers include zero‐dimensional carbon black, one‐dimensional multiwalled carbon nanotubes, two‐dimensional (2D) graphene nanoplatelets, and three‐dimensional (3D) functionalized graphene sheets, which are all efficient microwave‐absorbing materials that can transform microwaves into heat energy. As a result, the temperatures of the nanocomposites increased more rapidly than pristine ESMP in microwaves. The functionalized graphene sheets were found to transform the microwaves into heat more efficiently than the other nanofillers. Possible microwave propagation paths in the nanocomposites were proposed. Moreover, the nanocomposites displayed significantly higher mechanical strengths than pristine ESMP. The low cost and strong nanocomposites with fast microwave responses may be applied as actuators or deployable devices in medical treatments. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45676.