| 摘要 |
PURPOSE:To improve the bending strength and toughness of the title sintered body by dispersing a metal or its compd. in the composition wherein the molar ratio of the SiO2 to the oxide of a group IIIa element is specified in an Si3N4- SiO2-oxide of a group IIIa element based sintered body. CONSTITUTION:The metallic Nb, Ta, Ti, W, and Mo or their compds. are dispersed in the silicon nitride matrix wherein the molar ratio of the SiO2 to the oxide of a group IIIa element is controlled to >=1 in the three-component silicon nitride-based sintered body (Si3N4-SiO2-oxide of a group IIIa element). Since the metal to be added is hardly melted and deformed at high temp. and has a relatively low thermal expansion coefficient, the bending strength is not sufficiently increased only by adding the metals or their compds. to the three- component body. However, the toughness can be remarkably improved without deteriorating the bending strength by applying the metals or their compds. to the composition wherein the molar ratio of the SiO2 to the oxide of a group IIIa element is controlled to >=1, and sintering the composition. |
