Dielectric and microwave absorption properties of SiCnw-SiBCN composite ceramics deposited via chemical vapor infiltration

Silicon-boron carbonitride ceramics (SiBCN) containing various contents of silicon carbide nanowires (SiC_nw) were fabricated via chemical vapor infiltration. The effects of SiC_nw content on the morphology, microstructure, phase composition, dielectric and electromagnetic wave (EMW) absorption of the composite ceramics were investigated. Randomly oriented SiC_nw contributes to the formation of a conductive network; this leads to an increase in the electrical conductivity. With the increase of the SiC_nw content, the dielectric constant and the dielectric loss linearly increased from 3.7 to 0.05 to 4.2 and 0.39, respectively. For the maximum SiC_nw mass fraction of 3.8 wt%, the reflection coefficient of composite ceramics attained its minimum value of −15 dB in the X band and the effective absorption bandwidth was 2.88 GHz. After the oxidation, the composite ceramics still had a relatively high dielectric loss. The SiC_nw-SiBCN composite ceramics exhibited excellent EMW absorption, indicating their great potential as high-temperature microwave absorption materials.