Hierarchical Carbon Nanotube-Coated Carbon Fiber: Ultra Lightweight, Thin, and Highly Efficient Microwave Absorber
Hierarchical Carbon Nanotube-Coated Carbon Fiber: Ultra Lightweight, Thin, and Highly Efficient Microwave Absorber
复制标题
DOI：
10.1021/acsami.8b06673
复制
发表时间：
2018-07-25
影响因子：
9.5
通讯作者：
Kar, Kamal K.
中科院分区：
文献类型：
--
作者：
Singh, Sandeep Kumar;Akhtar, Mohammad Jaleel;Kar, Kamal K.
强电磁波吸收和重量轻是推动现代微波吸收剂实际应用的最重要因素。本工作主要涉及高效微波吸收器的设计，其中，首先通过催化化学气相沉积方法在碳纤维（CF）上生长分级碳纳米管（CNT）森林。然后将生长在碳纤维上的分级碳纳米管（CNTCF）嵌入环氧树脂基体中，合成轻质纳米复合材料，用作高效的微波吸收剂。形态学研究表明，碳纳米管（CNTs）在碳纤维表面自组装形成捕获中心。所得纳米复合材料的电磁特性的研究专门在X波段（8.2 - 12.4 GHz）使用网络分析仪。合成的纳米复合材料，含有0.35和0.50重量%的CNTCF，表现出优异的微波吸收性能，这可能是由于更好的阻抗匹配条件和高的介电损耗。在2.5mm厚度下，对于0.35wt%CNTCF负载，实现了-42.0dB（99.99%吸收）的反射损耗（RL），其中-10dB（90%吸收）和-20dB（99%吸收）带宽分别为2.7和1.16GHz。具有0.50wt%CNTCF负载的复合材料示出了相当大的吸收效率，其中RL在9.8GHz下达到-24.5dB（99.65%吸收），并且-IOdB带宽包括整个X频带的84.5%。在这里获得的优异的微波性能主要是由于电偶极极化，界面极化，和独特的捕获中心。这些俘获中心基本上引起多次反射和散射，这衰减了更多的微波能量。这项研究为X波段应用的极轻、小厚度和高效的微波吸收剂的开发开辟了新的途径。
Strong EM wave absorption and lightweight are the foremost important factors that drive the real-world applications of the modern microwave absorbers. This work mainly deals with the design of highly efficient microwave absorbers, where a hierarchical carbon nanotube (CNT) forest is first grown on the carbon fiber (CF) through the catalytic chemical vapor deposition method. The hierarchical carbon nanotube grown on the carbon fiber (CNTCF) is then embedded in the epoxy matrix to synthesize lightweight nanocomposites for their use as efficient microwave absorbers. The morphological study shows that carbon nanotubes (CNTs) self-assemble to form a trapping center on the carbon fiber. The electromagnetic characteristics of resultant nanocomposites are investigated exclusively in the X-band (8.2-12.4 GHz) using the network analyzer. The synthesized nanocomposites, containing 0.35 and 0.50 wt % CNTCFs, exhibit excellent microwave absorption properties, which could be attributed to the better impedance matching conditions and high dielectric losses. The reflection loss (RL) of -42.0 dB (99.99% absorption) with -10 dB (90% absorption) and -20 dB (99% absorption) bandwidths of 2.7 and 1.16 GHz, respectively, is achieved for 0.35 wt % CNTCF loading at 2.5 mm thickness. The composite with 0.50 wt % CNTCF loading illustrates substantial absorption efficiency with the RL reaching -24.5 dB (99.65% absorption) at 9.8 GHz and -10 dB bandwidth comprising 84.5% of the entire X band. The excellent microwave properties obtained here are primarily due to the electric dipole polarization, interfacial polarization, and unique trapping center. These trapping centers basically induce multiple reflections and scatterings, which attenuate more microwave energy. This investigation opens a new approach for the development of extremely lightweight, small-thickness, and highly efficient microwave absorbers for X-band applications.