Preparation and Properties of High Strength Porous Si3N4 Ceramics

High strength and high porosity porous silicon nitride ceramics were prepared by tert-butyl alcohol (TBA)-based gel-casting process and pressureless sintering. At a fixed solid loading of 10 vol% of the initial slurry, the influence of the sintering temperature and holding time on the porosity, pore size distribution, phase and microstructure was discussed. The relationship between flexural strength and microstructure was also discussed. The results show that porous silicon nitride ceramics with high porosity ranging from 63.3% to 68.1% can be prepared by adjusting the sintering temperature or holding time. A uniform pore size distribution was observed, and the mean pore size ranges from 0.94 to 1.42 mu m. The flexural strength shows an increased trend with the sintering temperature or holding time increasing and it reaches (74.2 +/- 8.8) MPa at 1750 degrees C held for 1.5 h.