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. [Display omitted] •The carbon foam, SiC coating and SiC nanowires together constituted the hierarchical structure.•The optimal RL value of SnwSCF achieved −31.216 dB at 15.76 GHz at 1.5 mm absorber thickness.•The incident EM waves experienced multiple microwave energy attenuation processes in the hierarchical structure.•The hierarchical structure possesses greater potential in the microwave absorbing field.•It could provide scientific guidance for the microstructure design of advanced EM absorber.