Nitrogen-doped bean-like SiC-based nanofibers for thermal insulation and electromagnetic wave absorption

SiC nanofibers that can be used to absorb electromagnetic wave (EMW) radiation and as thermal insulators simultaneously are highly desirable. In this work, nitrogen-doped bean-like SiC-based nanofibers were prepared by a simple electrospinning and high-temperature pyrolysis in a nitrogen atmosphere, focusing on studying the effects of nitrogen atom doping on the microstructure, EMW absorption, and thermal insulation properties of the fibers. The results showed that nitrogen doping promoted the formation of the SiOxCyNz phase in the fibers, which improved their interfacial thermal resistance and endowed the fibers with extremely low thermal conductivities (∼0.024 W·m ⁻¹·K ⁻¹ at 25 ℃, 0.092 W·m ⁻¹·K ⁻¹ at 1000 ℃). Furthermore, the density of carbon defects in the fibers was improved by nitrogen doping, which created numerous new polarization centers and effectively improved the dielectric loss. With a 4 mm thickness, a minimum reflection loss of −51.8 dB was exhibited at 6.3 GHz, indicating that these fibers are highly promising as an absorption material in harsh environments.