Nitride capacity of the molten CaO-SiO2-Al2O3 system containing TiO2 or ZrO2 and equilibrated with molten Si

Nitride capacity of molten CaO-SiO2-Al2O3 containing TiO2 or ZrO2 was obser ved. The molten oxides were equilibrated with nitrogen gas of 1013 hPa and with metallic Si to controll acculately oxygen partial pressure in the oxid e phase. The experimental procedure was developed by the authors. It is estimated that oxygen partial pressure in the molten oxide phase was controlled by the following reaction equation. CaO-Sio(2)-Al2O3 system: Si+O-2=SiO2 CaO-Sio(2)-Al2O3-TiO2 system: TiO2+4Si +O-2=TiSi2+2SiO(2) CaO-Sio(2)-Al2O3-ZrO2 system: SrO2+4Si+O-2=ZrSi2+2SiO(2) The nitride capacities measured by the procedure are comparatively same as that reported by other investigators.