Preparation and Properties of Si<sub>3</sub>N<sub>4</sub>-SiC Radar Wave-Absorbing Nanocomposites

Abstract

The vacuum-sintering technology was adopted to prepared Si3N4-SiC composite ceramic, a type of Radar Wave-Absorbing materials (RAW). The mechanical performances of the composite materials were tested and the influences of SiC powers on the mechanics performances and microstructure of Si3N4 ceramics were investigated. The results show that the sintering density, the content of size ofβ-Si3N4 and the strength of Si3N4-SiC all decrease along with the increase of SiC powers in sample, compared with the pure matrix Si3N4 .Meanwhile, Relationship between SiC content and relative permittivity of Si3N4-SiC within the frequency range of 8.2–12.4 GHz (X-band) was studied. The average of relative permittivityεof Si3N4-SiC increased from 7.878 to 13.88 and the average of dielectric loss tanδincreased from 5.6×10-3 to 0.7869 when the content of SiC increased from 0 to 15 wt.%. The excellent microwave absorbing abilities of Si3N4–SiC ceramic were attributed to the interfacial polarization at interface between Si3N4 and SiC and at grain boundary between SiC nanocrystals.