填充复合型聚合物基电磁屏蔽材料研究进展

综述了近年来填充复合型聚合物基电磁屏蔽材料的国内外最新研究进展，按照填料结构形态（纳微粒子颗粒型填料、高长径比结构填料、片层结构填料、三维网状框架结构填料），对相关复合材料电磁屏蔽性能数据进行统计和对比。围绕构筑高效导电网络的目标，从导电填料选择与处理、基体结构设计与制备方法等角度对聚合物基电磁屏蔽材料进行详细分析与总结，阐明了聚合物基电磁屏蔽材料研究现状及关键问题，阐述了聚合物基电磁屏蔽材料的研究方向和未来发展趋势。     

电磁屏蔽材料的研究进展

阐述了研究电磁屏蔽材料的重要性。综述了表层导电型、填充复合型、本征型导电高分子、导电织物、透明导电薄膜等电磁屏蔽材料的性能及特点,简要阐述了电磁屏蔽材料的发展趋势。     

填充型电磁屏蔽复合材料

介绍了电磁辐射的危害以及发展电磁屏蔽材料的意义,阐述了电磁屏蔽的原理。综述了导电填料的种类、形态、填充量、复配、分散与分布等因素对填充型电磁屏蔽复合材料屏蔽效能的影响及研究进展。     

电子设备机壳材料的电磁屏蔽设计和腐蚀防护

本文强调了在电子设备机壳材料的电磁屏蔽设计中，重视腐蚀防护对延长产品寿命及确保其电磁屏蔽效果长期有效性的重要性。遵循电化学腐蚀原理阐述了机壳防腐蚀设计的一般原理和方法。     

关于飞机电缆电磁屏蔽完整性的探讨

飞机电气线路互联系统中,电缆线束屏蔽端接处理的方式决定着电磁屏蔽的完整性,直接影响飞机电磁兼容和防护效能。针对部分现役飞机线束中存在的多根电缆屏蔽层引线串联端接的情况,从电磁屏蔽原理出发,对"pigtail"效应进行定性分析,并结合相关行业标准,给出电缆线束屏蔽端接处理方式的一些建议。     

镀金属碳毡在电磁屏蔽材料中的应用

将三维网络结构的碳毡引入电磁屏蔽材料的应用，对其特有的电磁性能及网络结构作了分析，并进行了复合材料屏蔽效果计算和修正。研究表明：利用碳毡的孔洞结构和尺寸，辅之以金属镀层，能在较宽的频率内对电磁波有良好的屏蔽效率，且不需要很大的填充量。     

微波暗室屏蔽层接地的考虑

本文就６１５微波暗室（射频无反射室）屏蔽层的接地设计技术展开了讨论。指出了接地的种类，接地电阻的大小与土壤的类型及其电阻率（系数）等因素的关系，同时论述了该屏蔽层接地电阻的设计与埋设方案的实施。     

全机电子综合试验电磁屏蔽暗室

本文简要说明了全机电子综合试验电磁屏蔽暗室的必要性、优越性，电磁屏蔽暗室的用途以及电磁屏蔽暗室的技术要求和设计原理。     

民航VHF设备电磁屏蔽技术探讨

本文结合实际工作经验对民航VHF设备电磁屏蔽技术进行了探讨研究，总结VHF设备电磁屏蔽应注意的问题，以供同行参考。     

层状Ti3C2Tx/水性聚氨酯复合双层薄膜的制备及电磁屏蔽性能

采用交替真空抽滤制备Ti_3C_2T_x MXene/WPU复合双层薄膜,用扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征了微观形貌,X射线衍射仪(XRD)测试了晶体结构,通过矢量网络分析仪测试了电磁屏蔽性能。结果表明,可以通过超声离心制备出少层Ti_3C_2T_x;复合双层薄膜具有高韧性、高导电性以及优异的电磁屏蔽性能,表面电阻为3.57Ω;电磁屏蔽性能结果表明,MWPU_(3:1)的复合薄膜屏蔽性能为37.9 dB。在X波段与K波段,MWPU_(3:1)复合薄膜性能较为优异,且复合薄膜是吸收型电磁屏蔽材料。     

Electromagnetic characteristics of carbon nanotube film materials

Carbon nanotube(CNT) possesses remarkable electrical conductivity, which shows great potential for the application as electromagnetic shielding material.This paper aims to characterize the electromagnetic parameters of a high CNT loading film by using waveguide method.The effects of layer number of CNT laminate, CNT alignment and resin impregnation on the electromagnetic characteristics were analyzed.It is shown that CNT film exhibits anisotropic electromagnetic characteristic.Pristine CNT film shows higher real part of complex permittivity, conductivity and shielding effectiveness when the polarized direction of incident wave is perpendicular to the winding direction of CNT film.For the CNT film laminates, complex permittivity increases with increasing layer number, and correspondingly, shielding effectiveness decreases.The five-layer CNT film shows extraordinary shielding performance with shielding effectiveness ranging from 67 d B to78 d B in X-band.Stretching process induces the alignment of CNTs.When aligned direction of CNTs is parallel to the electric field, CNT film shows negative permittivity and higher conductivity.Moreover, resin impregnation into CNT film leads to the decrease of conductivity and shielding effectiveness.This research will contribute to the structural design for the application of CNT film as electromagnetic shielding materials.     

一种可控透波材料电磁性能分析

采用多次化学切换手段考察了一种可控透波材料在不同次数切换前后的透波性能、屏蔽性能、切换时间、表面形貌。结果表明:切换次数10次以内,6~18 GHz材料透波状态透波率随切换次数变化较小,透波态透波率均大于90%,但材料屏蔽状态屏蔽性能增强,屏蔽态反射率均大于44%,透波/屏蔽切换时间变长,屏蔽态到透波态切换时间均在10 s内,透波态到屏蔽态切换时间均在30 s内,表面有氯化铵生成。     

电磁屏蔽抗干扰技术研究

从干扰源性质出发,将屏蔽分为电场屏蔽、磁场屏蔽和电磁场屏蔽,并对它们进行了分析研究。针对其特性提出其适用范围及注意事项,从而增强了抗干扰的效果。     

Studies of Electromagnetic Properties of MWCNTs after Electroless Plating with Co-Fe Alloy

A method of electroless plating is utilized to deposit Co-Fe alloy on the surface of multi-walled carbon nanotubes (MWCNTs), and electromagnetic parameters of MWCNTs with and without electroless plating are discussed. The MWCNTs covered by Co-Fe is a desirable light absorbent in wide wave band by utilizing electroless plating process in experiments. Field-emission scanning electron microscope (FESEM) and field-emission transmission electron microscope (FETEM) images as well as energy dispersive spectroscopy (EDS) results are presented to show the morphology, components and electromagnetic parameters of MWCNTs. Electromagnetic properties of MWCNTs are enhanced after electroless plating observed from contrast of results between MWCNTs with and without plating. In conclusion, the covering Co-Fe on the surface of MWCNTs in 2-18 GHz frequency range has better electromagnetic properties. When the material is in the 6.5 GHz electromagnetic waves, the reflection loss is up to ?10 dB, and the bandwidth more than ?4 dB is 5 GHz. The excellent electromagnetic properties make it probable for MWCNTs to be utilized as absorbent in electromagnetic shielding materials.     

Preparation of CF/Ni-Fe/CNT/silicone layered rubber for aircraft sealing and electromagnetic interference shielding applications

To meet the needs of preventing information leakage in space engineering and military industry, an efficient method was introduced to obtain layered electromagnetic shielding sealing rubber. The carbon fiber, Ni-Fe coating, and Carbon NanoTube (CNT) were combined by chemical plating and in-situ polymerization to obtain a lightweight (0.14 g/cm²) and thin (1 mm thick) Carbon fiber Fabric (CF)/Ni-Fe/CNT/silicone layered electromagnetic shielding composites. The layered material obtained by adjusting the electroless plating time exhibited a high Shielding Efficiency (SE) of 60.2–85.5 dB in the range of 0–4800 MHz, which can be used for aviation electromagnetic shielding. Carbon fibers and carbon nanotubes mainly attenuated electromagnetic waves through absorption loss, while the nickel-iron alloy coating through reflection loss interacted with the magnetic vector of incident ElectroMagnetic (EM) radiation and magnetic dipoles, therefore, the EM Interference (EMI) shielding composite attenuated EM waves with the “absorption-reflection-absorption” cooperative interaction. Moreover, the flexible fabric substrate adhered with silicone rubber possessed a breaking elongation of 52.3%, which can be utilized as a good sealing material. Simultaneously, the outstanding exothermicity (67.2 °C under the applied voltage of 5 V) makes it possible to be applied in electric heating area. The electromagnetic shielding composites prepared in this paper have good potential in the fields of precision electronic equipment and aviation systems.     

飞翼无人机保形进气道耦合进口格栅气动与隐身综合特性

基于飞翼无人机(UAV)保形进气道和工程应用实例,进行了不同格栅间距的格栅设计。结合多层快速多极子方法(MLFMM)和混合网格计算方法,开展了保形进口格栅气动和隐身综合特性研究。结果表明:①随着格栅尺寸（间距)减小,格栅隐身效果逐渐增强;频率为1GHz下,格栅间距为波长的1/3时,格栅电磁屏蔽效率约为48.93%,而当格栅间距达到波长的1/6时,接近于完全屏蔽;②保形进口格栅对无人机翼面上流动干扰较小而对进气道内流特性影响明显;③随着格栅尺寸减小,全机升阻特性逐渐略微下降,进气道出口截面总压恢复逐渐降低而畸变指数逐渐增大。      

GHz铁氧体电磁波吸收材料的研究

鉴于民用吸波材料市场的日益增加，用传统粉末冶金的方法制备了铁氧体吸收剂粉体，并测定了其内禀磁性能和电磁参数。采用吸收剂粉体与氯化聚乙烯复合的方法轧制出不同厚度的胶板，测定了10MHz～1．8GHz电磁波吸收性能及厚度的影响，复合胶板在400MHz～1．8GHz频段显示良好的吸收性能。降低吸收剂粉体的填充率有利于展宽频带，复合胶板在2GHz～10GHz频带的测试结果表明，反射系数小于-5dB的带宽达到3．6GHz，对应吸收率大于70％。样品的吸波性能已经具有一定的实用性。