Fabrication and properties of porous silicon nitride ceramics via microwave sintering

Porous silicon nitride ceramics were fabricated without pore formers via microwave sintering. Microwave sintering at different temperatures produced unique microstructures with high porosity. The best porous silicon nitride ceramics were fabricated at 1 550 degrees C for 30 min; the resulting product had a bulk density of 1 552 g cm(-3), an open porosity of 43.9 %, and a flexural strength of 43.6 MPa. The mean pore channel size and the dielectric constants of the fabricated porous silicon nitride ceramics ranged from 0.1 mu m to 1 mu m and 2.9 to 3.4 under different temperatures, respectively.