生物质碳管/高岭岩-双废材料的复合及其吸波应用

Biomass carbon tubes/kaolin rock-dual wastes derived composite for efficient microwave absorption

低成本、高性能和具有良好的环境稳定性是微波吸收剂实现应用的关键因素。本文以废弃梧桐飘絮生物质为碳源,煤矿废弃资源高岭岩为负载,通过优化界面作用并结合高温热解的方法合成了具有优异微波吸收性能的碳管/高岭岩双废复合材料。实验结果表明,经过酸改性的碳微米管(Acid-treatment carbon microtubes,CMT-ac)和碱改性的高岭岩(Alkali-treatment kaolin rock,KR-al)在高温碳化后结合良好,两者之间形成了大量的异质界面,且由于两者电导率的差异并在电磁波的辐照下容易形成界面极化效应,从而大大衰减电磁波。最终得到的KR-al@CMT-ac碳基矿物复合样品在仅在2.0 mm的匹配厚度下有效吸收带宽达到6.3 GHz(11.7~18.0 GHz),厚度为3.0 mm时在8.08 GHz处达到最小反射损耗−51.5 dB。吸波性能的提升得益于增强的界面极化和本身高电导损耗的共同作用。本研究将为低成本和高性能的介电型吸波材料的设计提供有效的策略。

Low cost,high performance,and good environmental stability are the key factors to determine the application of microwave absorbent.In this study,the wasted platanus tree fruits were taken as raw biomass materials,which were combined with the kaolin rock,one kind of abandoned coal mine resources,to construct the dual wastes-derived composite for microwave absorption.The obtained carbon microtubes/kaolin rock composite was optimized by controlling their interfacial interaction followed by high-temperature pyrolysis to reach efficient absorbing capability towards microwave radiation.The experimental results show that the acid-modified carbon microtubes(CMT-ac)and the alkali-decorated kaolin rock(KR-al)combined well to supply a large number of heterogeneous interfaces to strengthen the interfacial polarization mechanism.As a result,their conductivity difference under the irradiation of electromagnetic wave enabled greatly attenuating electromagnetic wave.The final KRal@CMT-ac sample achieved an effective absorption bandwidth of 6.3 GHz(11.7~18.0 GHz)at a matching thickness of only 2.0 mm and a minimum reflection loss of−51.5 dB at 8.08 GHz at a thickness of 3.0 mm.The improvement in microwave absorption performance is due to the enhanced interface polarization and conduction loss.This study will provide an effective strategy for the design of low-cost and high-performance dielectric absorbents.