Preparation and electromagnetic wave absorption properties of SiC/SiO₂ nanocomposites with different special structures

The special microscopic morphology and structure of electromagnetic (EM) wave absorbing materials are the key factors affecting their performance of EM wave absorption. In this work, three different special structures of SiO₂/SiC nanocomposites (hollow spherical SiO₂/SiC composite nanoparticles (HSPs), core–shell SiO₂/SiC composite nanofibers (CSFs) and core–shell SiO₂/SiC composite nanochains (CSCs)) are successfully prepared by self-assembly technology and high-temperature carbon thermal reduction method in a single crucible. The EM wave absorbing properties of them are investigated. The results show that HSPs have superior EM wave absorbing performance compared to CSCs and CSFs. The HSPs with a low filler loading of 10 wt% exhibit minimum reflection loss (RL_min) of −52.73 dB at 14.50 GHz with a thickness of 2.64 mm. Moreover, the maximum effective absorption bandwidth (EAB_max) is up to 7.79 GHz (10.21–18 GHz) under a corresponding thickness of 2.62 mm. The special hollow spherical structure not only provides a large number of interfaces to enhance interfacial polarization, but also improves impedance matching characteristics, resulting in excellent EM wave absorption performance of HSPs. Thus, this work provides a reference for the structural design of an ideal EM wave absorber.