Constructing core–shell SiC@C nanofiber network structures to enhance conductive loss for efficient microwave absorption

Abstract

The inherent impedance mismatch and limited electrical conductivity of SiC constrain its effectiveness as an electromagnetic wave absorber. However, rational microstructural design offers a viable strategy to enhance both impedance matching and conductive loss. In this study, core–shell structured SiC@C nanofibers were successfully fabricated via a coaxial electrospinning technique in combination with a high-temperature carbothermal reduction process. The hollow core–shell structure was formed by controlling the carbon thermal reduction temperature to achieve the diffusion reaction between carbon and SiO₂, which synergistically improved the impedance matching of the composite with SiO₂. Additionally, excess carbon enhanced the conductive properties of the composite. The interconnected nanofiber structure created a comprehensive three-dimensional conductive network. This integrated network significantly enhanced the composite's conductive loss mechanisms, which consequently led to superior electromagnetic wave attenuation capabilities. The composite exhibited outstanding electromagnetic wave absorption performance at 1450 °C, achieving a notable minimum reflection loss of −66.64 dB. Furthermore, at an optimal matching thickness of 2.09 mm, core–shell SiC@C nanofibers achieved a maximum effective absorption bandwidth of 7.52 GHz, covering the frequency range from 9.28 to 16.8 GHz. This work not only presents a strategy for designing core–shell structured SiC@C nanofibers, but also offers new insights into impedance matching regulation and the construction of efficient conductive networks.