Electromagnetic Properties of Nanometer SiC/CNTs Composite

Abstract

Both the complex permittivity and permeability of nanometer SiC and nanometer SiC/CNTs composite were investigated by Hewlett-Packard 8510B Network Analyzer. The results show that the complex permittivity of nanometer SiC/CNTs composite is much higher than that of nanometer SiC. Reflection curves of nanometer SiC and nanometer SiC/CNTs composite calculated with electromagnetic wave transmission-line theory show that the addition of CNTs at 6 wt%, 12 wt% and 18 wt% in nanometer SiC absorber can improve its microwave absorption properties strongly. There is a relationship between the mass fraction of CNTs and microwave absorption ability. With increase of the mass fraction of CNTs, its microwave absorption ability firstly increased then decreased. From the simulation, it was found that nanometer SiC with 12 wt% CNTs gave the optimum microwave absorption. The corresponding frequency of maximum reflection loss value of nanometer SiC/CNTs composite gradually moves to the low frequency range with increase of thickness. The maximum reflection loss value of nanometer SiC/CNTs composite (CNTs content is 12 wt%) was -25.74dB at the corresponding frequency of 11.60 GHz with a bandwidth under -5 dB (68% absorption) is 7.16 GHz when the thickness is 2.0 mm.

In situ synthesis of one-dimensional MWCNT/SiC porous nanocomposites with excellent microwave absorption properties

“…The minimum RL reaches À44.2 dB with a coating thickness of 2.0 mm for S400, À47.2 dB with a thickness of 2.2 mm for S300, and À33.3 dB with a thickness of 1.6 mm for S200. All of these values are superior to that in the literature, 18 demonstrating that the preparation method for the CNT/SiC composites greatly influence the EM wave absorbing performance. RL values of less than À20 dB (99% absorption) were achieved in the range 10.6-18 GHz with thicknesses of 1.6-2.2 mm for S400.…”

“…The in situ reactive preparation method in this work is different from that via the mechanical mixing reported in the literature, 18 meaning that the products exhibit discrepant features. From the TEM images, the products, especially S400 and S300, are 1D MWCNT/SiC porous nanocomposites that combine the features of carbon-containing materials to exhibit excellent microwave absorbing properties.…”

“…17 A nanometer SiC/CNT composite containing 12 wt% CNT fabricated by high energy ball milling could reach a minimum RL value of À25.74 dB with a thickness of 2 mm. 18 In the literature, very little information concerns the EM wave absorbing properties of CNT/SiC composites, 18 and it is still worthy to expect them to have excellent properties as EM wave absorbers. More intriguingly, if a nanomaterial combines 1D and porous features, especially a 1D porous nanocomposite comprised of carbon and SiC, what about its EM wave absorbing performance?…”