In-situ grown CNTs decorated SiCNWs for enhancing electromagnetic wave absorption efficiency

Abstract

The uniform growth of carbon nanotube (CNT)-decorated SiC nanowires (SiCNWs) to form a three-dimensional (3D) network can significantly enhance the interfacial polarization effect, making it a promising electromagnetic (EM) wave-absorbing material. Nevertheless, the dispersion of CNT-decorated SiCNWs is challenging. In this study, CNT/SiCNWs composites are successfully synthesized by the in situ growth of CNTs at different annealing temperatures under a N2 atmosphere. Specifically, the CNT-decorated SiCNWs form a 3D network by vapor-liquid-solid (VLS) mechanism. The relative complex permittivity of the CNT/SiCNWs composites notably increases with increasing in temperature, adjusting the microstructure and dielectric properties. When the annealing temperature is 900 °C, the minimum reflection coefficient (RCmin) of the CNT/SiCNWs composites decreases from -34.7 to -44 dB with the thickness of the composites increasing from 3.5 to 3.9 mm. The effective absorption bandwidth (EAB) includes 4.2 GHz in the X band of 8.2–12.4 GHz. The results indicate that the CNT/SiCNWs composites exhibit superior EM wave absorption, which is facilitated by the interfacial polarization, dipole polarization, and conduction loss. The 3D network offers multilayer channels for multiple reflections and the scattering energy of the EM waves. Therefore, the CNT/SiCNWs composites are promising high-efficiency microwave-absorbing materials.