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

Abstract

Silicon-boron carbonitride ceramics (SiBCN) containing various contents of silicon carbide nanowires (SiCnw) were fabricated via chemical vapor infiltration. The effects of SiCnw content on the morphology, microstructure, phase composition, dielectric and electromagnetic wave (EMW) absorption of the composite ceramics were investigated. Randomly oriented SiCnw contributes to the formation of a conductive network; this leads to an increase in the electrical conductivity. With the increase of the SiCnw 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 SiCnw 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 SiCnw-SiBCN composite ceramics exhibited excellent EMW absorption, indicating their great potential as high-temperature microwave absorption materials.