Novel, hierarchical SiC nanowire-reinforced SiC/carbon foam composites: Lightweight, ultrathin, and highly efficient microwave absorbers

The novel hierarchical SiC nanowire-reinforced SiC/carbon foam composites (SnwSCF) were prepared for the first time by carbonization, CVD, and CVI processes. Morphological results demonstrated that the hierarchical structure, composed of carbon foam with a SiC coating and SiC nanowires, was fabricated successfully. The hierarchical structure significantly improved the microwave-absorbing performance of the carbon foam. The optimal reflection loss value of SnwSCF achieved -31.216 dB at 15.76 GHz with a 1.5 mm absorber thickness. The corresponding effective absorption bandwidth was 4.1 GHz. Furthermore, the microwave-absorption mechanism of SnwSCF is discussed in depth. The incident EM waves were trapped in the hierarchical structure and experienced multiple microwave energy attenuation processes including multiple reflections, interface polarization, and dipole polarization. As a result, SnwSCF is believed to be a superior candidate to its competitors as an ultralight, ultrathin, and highly efficient microwave absorber. (C) 2020 Elsevier B.V. All rights reserved.