高性能气凝胶电磁波吸收材料的研究进展

Research Progress of High Performance Electromagnetic Wave Absorption Aerogel

摘要:

电磁波吸收材料是将电磁波能量转化为热能或其他形式能量的一类功能材料。随着5G技术、无线通信技术和高功率电子设备的普及，电磁污染日趋严重，已经成为了仅次于空气、水、噪声污染的第4大污染。因此，开发实用有效的电磁波吸收材料成为当务之急。气凝胶是一种具有三维多孔结构的材料，具有高比表面积、高孔隙率、低密度、大的传输路径等特点。气凝胶材料内部独特的高孔隙率、高比表面积能显著降低材料的有效介电常数及优化阻抗匹配，大的传输路径能延长电磁波的传输路径，增强对电磁波衰减能力。因此，气凝胶材料在电磁波吸收领域中受到了广泛关注。为此，对电磁波吸收材料的损耗机制（如导电损耗、极化损耗、涡流损耗等），以及气凝胶的常规合成策略（如冷冻干燥、超临界干燥、常压干燥等）进行了总结，归纳分析了气凝胶的种类（如碳基气凝胶、陶瓷基气凝胶、磁性气凝胶），探讨了气凝胶复合材料潜在的电磁波吸收机理，最后指出了气凝胶电磁波吸收材料的发展方向，以及在保温、隔热、疏水性、阻燃性等智能方面的应用潜力。尽管气凝胶材料在实验室的研究已经取得了显著的进展，但是在实际生产中仍然面临巨大挑战，为制备出多功能气凝胶电磁波吸收材料，需要进一步优化制备工艺和设备。本研究旨在为高性能气凝胶电磁波吸收材料的研究提供参考。（专精特新·电磁波吸收与屏蔽用新型材料的研究进展专辑十二之三)

Abstract:

Electromagnetic wave （EMW） absorbing materials are a class of functional materials that convert EMW energy into heat or other forms of energy. With the popularization of 5G technology， wireless communication technology and high-power electronic devices， electromagnetic pollution is becoming more and more serious， and has become the fourth largest pollution after air， water and noise pollution， so it is imperative to develop practical and effective EMW absorbing materials. Aerogel is a material with three-dimensional porous structure， which has attracted much attention because of its high specific surface area， high porosity， low density， and large transmission path. The unique high porosity and high specific surface area inside the aerogel material can significantly reduce the effective permittivity and further optimize the impedance matching； the large transmission path can prolong the EMW transmission path and enhance the EMW attenuation ability， therefore it has received much attention in the field of EMW absorption. The loss mechanisms of EMW absorbing materials are summarized， such as conductive loss， polarization loss， eddy current loss， etc.； while the conventional synthesis strategies of aerogels are summarized， such as freeze-drying， supercritical drying， atmospheric pressure drying， etc.； the types of aerogels are also analyzed， such as carbon-based aerogels， ceramic-based aerogels， magnetic aerogels， and the potential EMW absorbing mechanisms of the aerogels are deeply discussed. Finally， the multifunctionality of aerogel materials are outlined， such as thermal insulation， heat insulation， hydrophobicity， and flame retardancy， etc.， which is a great potential for aerogel application in EMW absorbing field. Although aerogel materials have made significant progress in the laboratory research， challenges still remain in mass production， which requires further optimization of the preparation process of aerogels.