Structural Design Strategies of Polymer Matrix Composites for Electromagnetic Interference Shielding:A Review

With the widespread application of electronic communication technology,the resulting electromagnetic radiation pollution has been significantly increased.Metal matrix electromagnetic interference(EMI)shielding materials have disadvantages such as high density,easy corrosion,difficult processing and high price,etc.Polymer matrix EMI shielding composites possess light weight,corrosion resistance and easy processing.However,the current polymer matrix composites present relatively low electrical conductivity and poor EMI shielding performance.This review firstly discusses the key concept,loss mechanism and test method of EMI shielding.Then the current development status of EMI shielding materials is summarized,and the research progress of polymer matrix EMI shielding composites with different structures is illustrated,especially for their preparation methods and evaluation.Finally,the corresponding key scientific and technical problems are proposed,and their development trend is also prospected.

"Three-in-One" Multi-Scale Structural Design of Carbon Fiber-Based Composites for Personal Electromagnetic Protection and Thermal Management

Wearable devices with efficient thermal management and electromagnetic interference(EMI) shielding are highly desirable for improving human comfort and safety. Herein, a multifunctional wearable carbon fibers(CF) @ polyaniline(PANI)/silver nanowires(Ag NWs) composites with a “branch-trunk” interlocked micro/nanostructure were achieved through "three-in-one" multi-scale design. The reasonable assembly of the three kinds of one-dimensional(1D) materials can fully exert their excellent properties i.e., the superior flexibility of CF, the robustness of PANI, and the splendid conductivity of Ag NWs. Consequently, the constructed flexible composite demonstrates enhanced mechanical properties with a tensile stress of 1.2 MPa, which was almost 6 times that of the original material. This is mainly attributed to the fact that the PNAI(branch) was firmly attached to the CF(trunk) through polydopamine(PDA), forming a robust interlocked structure. Meanwhile, the composite possesses excellent thermal insulation and heat preservation capacity owing to the synergistically low thermal conductivity and emissivity. More importantly, the conductive path of the composite established by the three 1D materials greatly improved its EMI shielding property and Joule heating performance at low applied voltage. This work paves the way for rational utilization of the intrinsic properties of 1D materials, as well as provides a promising strategy for designing wearable electromagnetic protection and thermal energy management devices.

Rational design of graphene/polymer composites with excellent electromagnetic interference shielding effectiveness and high thermal conductivity: a mini review

The integration and miniaturization of chips lead to inevitable overheating and increasing electromagnetic interference (EMI) problems, which threaten the performance, stability, and lifetime of electroniccomponents. Therefore, it is important to improve the heat dissipation and EMI shielding performancein device packaging for the steady operation of electronic products. In recent years, due to its intrinsic superior thermal conductivity, proper electrical conductivity, light-weight, and structural adjustability,graphene has been widely used as high thermal and conductive fillers incorporated in the polymer matrix to improve the thermal conductivity and electrical conductivity of composites. This review concludesthe recent development of graphene/polymer composites by using graphene as fillers to improve thethermal conductivity and EMI shielding effectiveness (EMI SE). The structure of graphene embedded inthe composites varies from zero-dimension (0D), one-dimension (1D) to two-dimensions (2D). Moreover,highly thermally and electrically conductive fillers with different dimensions were also modified on thegraphene to improve the composite performance. Finally, this review also makes prospects for the development trend of graphene/polymer composites with high thermal conductivity and EMI SE in the future.

Hydrogel-based composites beyond the porous architectures for electromagnetic interference shielding

With the rapid development of the electronic industry and wireless communication technology,electromagnetic interference(EMI)or pollution has been increasingly serious.This not only severely endangers the normal operation of electronic equipment but also threatens human health.Therefore,it is urgent to develop high-performance EMI shielding materials.The advent of hydrogel-based materials has given EMI shields a novel option.Hydrogels combined with conductive functional materials have good mechanical flexibility,fatigue durability,and even high stretchability,which are beneficial for a wide range of applications,especially in EMI shielding and some flexible functional devices.Herein,the current progress of hydrogel-based EMI shields was reviewed,in the meanwhile,some novel studies about pore structure design that we believe will help advance the development of hydrogel-based EMI shielding materials were also included.In the outlook,we suggested some promising development directions for the hydrogel-based EMI shields,by which we hope to provide a reference for designing hydrogels with excellent EMI shielding performance and multifunctionalities.

Nanocellulose-assisted preparation of electromagnetic interference shielding materials with diversified microstructure

Sustainable and renewable nanocellulose attracts more and more attention in various fields due to its high strength-to-weight ratio,small diameter,large aspect ratio,and abundant functional groups.The excellent properties and structural characteristics enabled a great potential of nanocellulose for efficient interactions with functional nanomaterials such as carbon nanotube,graphene,transition metal carbides/nitrides(MXenes),and metal nanoparticles,which is beneficial for preparing high-performance electromagnetic interference(EMI)shields.We review the advances in the nanocelluloseassisted preparation of composite films and aerogels for EMI shielding application.The nanocellulose-based composites are evaluated in terms of their EMI shielding performance and the shielding mechanisms,including conduction,polarization,and multiple reflections are summarized.In addition to the constituent structure and contents,we highlight the significance of the microstructure design in enhancing the EMI shielding performance of the nanocellulose-based EMI shields.Finally,the current challenges and outlook for these fascinating nanocellulose-based EMI shielding composites are discussed.

电子纺织品制备用丝网印刷技术的研究进展

总结电子纺织品制备用丝网印刷技术的研究进展。介绍了丝网印刷技术的工艺原理,分析了丝网印刷工艺参数对电子纺织品导电性能和印刷质量的影响。阐述了丝网印刷技术在电子纺织品领域的研究应用,包括人体监测、电磁屏蔽、能源收集及存储、人机交互界面等。展望了丝网印刷技术制备电子纺织品未来的研究方向。认为:未来应结合用户需求,深入挖掘电子纺织品的潜在应用;结合丝网印刷技术,加强电子设备间的联动性,构建电子纺织品体系。

电动汽车无线充电系统电磁屏蔽结构设计理论与试验研究

为研究屏蔽结构对电动汽车无线充电系统的影响,基于屏蔽效能理论建立屏蔽体厚度与屏蔽体材料参数的关系模型。根据不同厚度、不同屏蔽材料的单层屏蔽体对磁场的屏蔽效果,对比数值解与解析解,初步验证了所建立的屏蔽体厚度模型的适用性,在此基础上,提出安全电磁环境下厚度最小的复合无线充电屏蔽体结构,并通过电磁试验进行了验证。结果表明,以0.05 mm的超薄硅钢和2.52 mm的铁氧体作为双层屏蔽结构时,磁场强度达到安全限值,且传输效率达到90.92%,相较于传统铁氧体和铝板复合屏蔽结构,该结构厚度减小了1.95 mm。

导电高分子复合材料电磁屏蔽性能研究现状与展望

随着无线电通信等技术的不断发展,电子设备在便捷人们生活的同时所产生的电磁波也产生了严重的电磁污染问题。为了解决电磁污染问题,高性能电磁屏蔽材料的研究显得尤为重要。导电高分子复合材料是一种优异的电磁屏蔽材料,它可以通过填充填料与结构设计等方法满足材料在不同环境下的电磁屏蔽需求,在电子、通讯、航空航天等领域具有广泛的应用前景。介绍了电磁屏蔽机理,概述了导电高分子材料在电磁屏蔽领域中常用的制备方法,并重点介绍一些导电高分子基复合材料的电磁屏蔽效果。最后,展望了导电高分子材料未来的发展趋势,旨在为导电高分子材料在电磁屏蔽领域的研究提供方向和启示。

飞机座舱风档复合玻璃结构优化设计

提出了一种新的含透明导电膜的多层复合玻璃优化结构．这种复合玻璃在电磁波频率８～１８ＧＨｚ范围内有很高的电磁波功率反射率；在可见光波长０．４０～０．７６μｍ范围内有高的透光率．该复合玻璃可以用于飞机座舱风档结构，也可以用于大容器微波防护系统．

EAST极向场电源控制系统EMC屏蔽设计与应用

屏蔽是指对两个空间区域间进行金属隔离,以控制电场、磁场和电磁波由一个区域对另一个区域的感应和辐射。介绍了极向场电源系统在超导托卡马克(EAST)装置中的工作情况和工作环境的特殊性,电源系统运行中遇到的各种干扰问题,结合电磁兼容(EMC)理论,充分考虑屏蔽设计在控制系统中的重要性,对设备的干扰源进行近场和远场的定性分析,根据场源性质采取相对应的屏蔽措施。并结合EMC理论中的接地和滤波器设计,将各种干扰幅度降至最低。

光触发电子测压仪可靠性设计及分析

针对光触发电子测压仪在多点测试过程中容易受火炮膛内复杂环境(高温、高压、强电磁)的影响等问题,通过设计合理的光窗结构,增强测压仪外壳的密封性能和整体强度;采取在光窗处附着一层电磁屏蔽薄膜的措施,降低来自火炮发射时产生的电磁干扰。在模拟复杂条件下,采用有限元分析软件对改进后的测压仪光窗及壳体进行强度仿真,同时对壳体的电磁屏蔽性能进行分析。仿真结果表明:改进后的光触发电子测压仪壳体满足膛压测试要求,电磁屏蔽性能得到进一步改善。通过实验测试,验证光触发结构设计的合理性和有效性,达到系统的设计要求。

飞机电刹车系统电磁干扰产生机理及抑制方法

针对飞机电刹车系统力传感器信号上叠加有高幅干扰这一问题,通过对电刹车系统分析,认为电机三相电流以及机电作动控制器(EMAC)输出PWM波为主要干扰源,电缆线路之间的耦合干扰是造成干扰的主要原因。建立了线路耦合干扰的数学模型,并据此采用电磁屏蔽、线路绞合和有效接地来减少线路耦合,并在EMAC输出端设计了无源EMI滤波器。通过这些改进,极大地减弱了干扰,提高了系统电磁兼容性,保证了刹车力伺服系统正常工作。

立体定向伽玛射线全身治疗装置治疗室的屏蔽设计

根据立体定向伽玛射线全身治疗装置的结构和原理 ,计算了治疗室内散射线的能量分布 ,并据此对某一实际治疗室的墙壁、顶棚和防护门进行了屏蔽设计。

汽车车身缝隙的电磁屏蔽特性仿真研究

汽车车身缝隙是汽车电磁干扰的重要耦合途径。通过分析汽车车身缝隙的结构,提出车身缝隙的简化模型,进而建立其仿真计算模型;分别改变车身缝隙模型的相关结构参数,考察相应的电磁场屏蔽效能的变化。仿真结果表明,车身缝隙越长,屏蔽效能越低,电磁干扰越容易耦合进车内;车身缝隙越窄,电磁屏蔽效能越高;改变车身缝隙搭接部分的长度和拐角角度并不能保证提高其屏蔽效能,具体变化趋势与频率范围有关。

电磁屏蔽技术在结构设计中的应用

结合电磁兼容和电磁屏蔽的基础知识,分析电磁屏蔽的机理。从结构设计角度出发,阐述结构设计中电磁屏蔽的设计方法。针对各种引起电磁泄漏的途径,给出具体的电磁屏蔽结构设计方案。

水力发电站智慧防雷措施与检测

因水力发电站储水容量较大,容易形成雷雨天气,同时造成雷击的多发,给水力发电站带来巨大危害。为保障水力发电站安全运行,解决水力发电站耐雷水平,降低雷击雷电破坏损失,该文在介绍雷电防护检测一般原则和常用方法的基础上,提出水力发电站防雷布局设计总体要求,并针对重点检测部位提出具体措施,以期为水力发电站智慧防雷提供参考。

地下工程中金属门非核电磁脉冲屏蔽效能研究

以圆形截面坑道为简化模型,运用旋转对称体时域有限差分法将三维问题转化为二维问题处理,计算了地下防护工程口部金属门对高功率微波、超宽带电磁脉冲的屏蔽效能,分析了门缝大小、门框嵌入岩土介质深度对屏蔽效能的影响,确定了场泄漏的主要途径。计算结果表明,门对坑道中不同的传输波模具有不同的屏蔽效能;泄漏场主要是通过门框的绕射进入工程内部,门缝的泄漏较小,门缝大小以及门框嵌入岩土介质的深度对屏蔽效能的影响是次要的;另外,通过门的泄漏场在工程内部迅速衰减;HPM的载频越高,UWB的脉宽越窄,门的屏蔽效能越好。最后对数值计算结果和实验测得数据进行了比较,二者吻合较好,证实了数值计算的有效性。

浅析电磁屏蔽技术在电子方舱中的应用

简要阐明了研究方舱电磁屏蔽技术的重要性,介绍了军用方舱电磁屏蔽要求以及电磁屏蔽原理;从实践和应用的角度,分析了蒙皮处理的开孔处理对提高电磁屏蔽性能的作用,并总结了电磁屏蔽方舱设计的要点;提出有待完善的建议,待后续工作研究。

舰载电子设备的三防设计

防潮湿、防霉菌、防盐雾的三防设计是研制服役于海洋气候环境下的舰载电子设备的重要任务,产品研制时即应从材料应用、结构设计和工艺技术等诸方面进行系统性三防设计。正确、合理地应用耐蚀性好的金属材料和不长霉、耐老化的非金属材料是三防设计的基础。大多数的腐蚀都能通过合理的结构设计来避免,结构设计的合理性对设备的环境适应能力影响最大,是舰载电子设备三防设计的关键。恰当地应用材料改性、表面镀涂、浸渍、灌封和绝缘处理等具有良好防护效果的工艺技术,进一步提高设备的三防能力。目前,覆膜技术仅能解决L波段低频段以下电路组件的三防问题,微波/毫米波电路组件应用环境密封和电磁屏蔽复合技术可有效杜绝普遍性的电化偶腐蚀的发生,保证了组件的恶劣气候环境适应性和在0.1～10GHz工作频段内的屏蔽性能大于80dB,且可满足3m水深浸渍的防水要求。微组装了裸芯片等集成电路的毫米波收发组件则采用气密封装技术实现其三防设计,氦质谱检测漏率符合小于1×10-8Pa·m3/s的国军标要求,有效地保证了电路组件的可靠性。

空间遥感器电控箱结构设计

空间遥感器电控箱的在轨不可维修性要求其具有高的电磁屏蔽能力和力学稳定性。针对电磁屏蔽能力和力学稳定性要求,设计了一种框架式结构的双腔隔离电磁屏蔽结构。该结构主体采用稳定的框架式结构,力学性能好。电控箱整体结构分为两个封闭的腔体,一个腔体用来承载电子学器件,一个腔体负责数据信号的转出,具有极高的电磁屏蔽能力。通过反应电控箱结构屏蔽能力的电场辐射抗扰度试验(RS103)和电场辐射发射试验(RE102)证明了该结构的电磁屏蔽效果满足航天应用需求。并且,对整个结构进行了有限元分析和动力学试验,基频是235HZ,满足设计要求的120HZ,双腔隔离电控箱具有优良的力学性能和极高的电磁屏蔽能力。