Abstract
Effects of the additives on sintering of Si 3N4 have been studied. As the additives, Al(OH) 3, Al powder, A1PO4, AIN, SiC, Si powder, SiO2, MgO, TiO2, BN, Fe2O3, etc. were used. The powder of Si 3N 4 was mixed with 1, 3 or 5 wt. % of the additive, and then was pressed isostatically at 1000 kg/cm2. Sintering was done in the N 2 atmosphere at 1530°C for 4 hours. The most effective additive was MgO at 5 wt. %, followed by MgO at 3 wt. %, and the third was Al(OH) 3 at 5 wt. %. Moduli of rupture of these bodies were 830 kg/cm2, 664 kg/cm2, and 414 kg/cm2 respectively.
