Mechanical and dielectric properties of porous Si3N4-SiC(BN) ceramic

Polymer-derived nano-sized SiC(BN) was successfully introduced into porous Si3N4 ceramic by precursor infiltration pyrolysis (PIP). After PIP, the porous Si3N4-SiC(BN) ceramic possesses improved mechanical properties and excellent dielectric properties. As the annealing temperature increases from 900 degrees C to 1800 degrees C, the mechanical properties of porous Si3N4-SiC(BN) ceramic improve little, the real part and imaginary part of the permittivity of porous Si3N4-SiC(BN) ceramic increase obviously with the dielectric loss increasing gradually over the frequencies ranging from 8.2 GHz to 12.4 GHz. The increase of dielectric loss is due to the dipolar polarization and the increase of grain boundary as the annealing temperature increases. (c) 2009 Elsevier B.V. All rights reserved.