核壳结构电磁波吸收材料研究进展

Research Progress of Electromagnetic Wave Absorbing Materials with Core-Shell Structure

微波通信技术的发展和广泛应用,在方便人们生活的同时,产生的大量电磁波会对环境造成污染,从而威胁人们的身体健康。电磁波吸收材料(也称吸波材料)可以吸收多余的、泄漏的电磁波能量,在治理电磁波污染方面有着十分重要的经济价值与社会效益。此外,在军事工业领域,雷达隐身飞机、导弹、作战指挥车等军事装备也对吸波材料有着极为紧迫的需求,不仅要求吸波材料具有薄、轻、宽、强的特点,还要求其具有耐高温、抗氧化、高强度等性能。传统吸波材料(如铁氧体、羰基铁、导电炭黑)的损耗机制单一,导致其吸波频带窄、吸收能力不够强,复合化处理就成为获得优良性能吸波材料的必要手段。通常人们采取多层宏观尺度结构匹配的方式来达到宽波段吸收的目的,但通过该方法得到的吸波材料匹配厚度大,适用领域十分有限,很难同时满足吸波材料薄、轻、宽、强的要求。纳米科学技术的发展使得材料的设计与制备拓展到了原子级别,人们试图从纳米尺度上对吸收材料进行阻抗匹配设计与损耗能力改进,其中核壳结构吸波材料由于结构设计自由度大、性能优异,逐渐成为该领域的研究热点。近年来,对核壳结构吸波材料的探究主要是从材料本身的特性出发,采用不同损耗特性的材料进行包覆,并结合对材料微观结构和形貌的设计,来提高吸波材料的匹配特性和有效波频带宽度。其中,具有中空核壳结构和各向异性的材料(如二维片状、纳米花状、纳米管状)表现出更优异的吸波性能。此外,可选用陶瓷材料和耐温树脂作为壳层材料,以满足吸波材料的耐高温和抗氧化性能的要求。目前虽对核壳结构吸波材料的报道较多,但其研究体系尚未统一,吸波调控机理也仍有待深入研究。本文基于核壳结构吸波材料最新的研究进展,介绍了已报道的核壳结构吸波材料的类型,分析了核壳结构吸波材料的微观调控机制和制备方法。最后,对核壳结构吸波材料的发展进行了总结和展望。

Microwave communication technology has been greatly developed and widely used,which facilitates people’s life.At the same time,a large number of electromagnetic waves also pollute the environment and threaten people’s health.Electromagnetic wave-absorbing materials,also known as wave-absorbing materials,can absorb the excess and leakage electromagnetic wave energy,which has very important economic value and social benefits in the treatment of electromagnetic wave pollution.In addition,in the field of military industry,radar stealth aircrafts,missiles,combat command vehicles and other military equipments also have a very urgent demand for wave-absorbing materials,which not only requires that the wave-absorbing materials have the characteristics of thin,light,wide and strong,but also requires high temperature resistance,oxidation resistance and high strength.Due to the single loss mechanism of traditional wave-absorbing materials,such as ferrite,carbonyl iron,conductive carbon black,the absorption band is narrow and the absorption capacity is not strong enough.Composite treatment becomes a necessary means to obtain excellent wave-absorbing materials.The multilayer macroscopic scale structure matching is usually adopted to achieve the purpose of wide band absorption.However,the matching thickness of wave-absorbing materials obtained by this method is large,and the applicable fields are very limited.It is difficult to meet the requirements of thin,light,wide and strong of wave-absorbing materials at the same time.With the development of nanotechno-logy,the design and fabrication of materials have been extended to the atomic level.People try to improve the impedance matching and loss ability of wave-absorbing materials on nanoscale.The core-shell structure wave-absorbing materials have gradually become a research hotspot in this field because of their high degree of freedom in structure design and excellent performance.In recent years,the research on core-shell structure wave-absorbing materials is mainly based on the essential properties of the materials.The materials with different loss characteristics are used to composite.Combining with the design of the microstructure and morphology of the mate-rials,the impedance matching characteristic and the effective bandwidth of the wave-absorbing materials are improved.Among them,materials with hollow core-shell structure and anisotropy,such as two-dimensional flake,nanoflower,nanotube,exhibit better wave-absorbing properties.In addition,ceramic materials and heat-resistant resins can be selected as shell materials to meet the requirements of high temperature and oxidation resistance of wave-absorbing materials.At present,although there are many reports on core-shell structure wave-absorbing materials,the research system of core-shell structure wave-absorbing materials has not been unified,and the regulation mechanism still needs to be further stu-died.In this paper,based on the latest research progress of core-shell structure wave-absorbing materials,we introduced the reported types of core-shell structure wave-absorbing materials,and analyzed the microcosmic regulation mechanism and preparation methods of core-shell structure wave-absorbing materials.Finally,the development of core-shell structure wave-absorbing materials was summarized and prospected.