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 °C to 1800 °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.