Article ID Journal Published Year Pages File Type
1462001 Ceramics International 2012 6 Pages PDF
Abstract

Si3N4–SiCN composite ceramics were successfully fabricated through precursor infiltration pyrolysis (PIP) method using polysilazane as precursor and porous Si3N4 as preform. After annealed at temperatures varying from 900 °C to 1400 °C, the phase composition of SiCN ceramics, electrical conductivity and dielectric properties of Si3N4–SiCN composite ceramics over the frequency range of 8.2–12.4 GHz (X-band) were investigated. With the increase of annealing temperature, the content of amorphous SiCN decreases and that of N-doped SiC nano-crystals increases, which leads to the increase of electrical conductivity. After annealed at 1400 °C, the average real and imaginary permittivities of Si3N4–SiCN composite ceramics are increased from 3.7 and 4.68 × 10−3 to 8.9 and 1.8, respectively. The permittivities of Si3N4–SiCN composite ceramics show a typical ternary polarization relaxation, which are ascribed to the electric dipole and grain boundary relaxation of N-doped SiC nano-crystals, and dielectric polarization relaxation of the in situ formed graphite. The Si3N4–SiCN composite ceramics exhibit a promising prospect as microwave absorbing materials.

Related Topics
Physical Sciences and Engineering Materials Science Ceramics and Composites
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