Tunable EMW absorption properties of a novel SiC–SiO2/3Al2O3·2SiO2 composite ceramic

Abstract

A kind of SiC–SiO2/3Al2O3·2SiO2 composite ceramic was successfully prepared by the technique of chemical vapor infiltration (CVI) for enhanced electromagnetic wave (EMW) absorption properties. Due to the weak EMW absorption performances of the pure SiO2/3Al2O3·2SiO2 ceramic, SiC nanocrystals as absorbers were introduced to improve the EMW absorption performances. The existences of SiC nanocrystals are beneficial for enhancing the EMW absorption performances, and the SiC-nanocrystal contents can be tailored in the SiO2/3Al2O3·2SiO2 ceramics. Although the SiC nanocrystals are helpful for the dielectric and EMW absorption properties, they are unfavorable for impendence matching owing to weak-absorption and strong-reflection if the SiC nanocrystals exceed the threshold value. According to the investigation, it can attain wonderful EMW absorption properties when the SiC-nanocrystal content is 77.1 wt% in the composite ceramic. The results show that the value of RC can reach −22.4 dB at 9.9 GHz, and the EAB is the complete X-band for the SiC–SiO2/3Al2O3·2SiO2 composite ceramics. And they can be tailored for the dielectric properties to obtain the excellent EMW absorption properties in the prepared SiC–SiO2/3Al2O3·2SiO2 composite ceramics. The mechanisms of EMW consumptions are Debye relaxation, dipole polarization, interfacial polarization, multi-reflection, multi-scattering and conductivity loss in the SiC–SiO2/3Al2O3·2SiO2 composite ceramics.