Silicon nitride based sintered body and method for producing the same.

摘要

The invention relates to a silicon nitride based sintered body composed only of uniform, fine crystal grains, which possesses improved strength and fracture toughness in the middle and low temperature ranges. A crystalline silicon nitride powder composed of crystal grains whose longer-axis diameter is not more than 200 nm or an amorphous silicon nitride powder is used as the material powder. The silicon nitride powder is sintered at a temperature of 1200 DEG C to 1400 DEG C or sintered with a product of sintering temperature ( DEG C) and sintering time (sec) below 600000 ( DEG C.sec) at a temperature of 1400 DEG C to 1900 DEG C. Thus, a silicon nitride based sintered body in which the longer-axis diameter of silicon nitride and/or sialon crystals is not more than 200 nm is obtained.