METHOD FOR MANUFACTURING SINTERED COMPACT OF SILICON NITRIDE, AND SINTERED COMPACT OF SILICON NITRIDE

PROBLEM TO BE SOLVED: To provide a method for manufacturing a sintered compact of silicon nitride that does not necessititate expensive equipment and complex control and is capable of efficeintly nitriding silicon even if the ratio of silicon in a raw material powder is high and has good dimentional precision, and further that has high density(dense) and high strength and is excellent in a void property, and to provide a sintered compact of silicon nitride. SOLUTION: The sintered compact of silicon nitride is obtained by grinding a mixed powder of the silicon nitride powder of which the particle diameter is 5-40μm when the cumulative particle size distribution is 90% and the silicon powder of which the weight ratio to the silicon nitride powder is 1 or more as main components and 1-20wt.% of the group 3a element in the periodical table calculated in term of the oxide, 1-10wt.% of alminum calculated in term of the oxide and 1-10 wt% of excess oxygen calculated in terms of silicon oxide, so that the BET specific surface area becomes 6-14 m2/g, molding the resultant to a desired shape, heat-treating the molding in a nitrogen-containing atmosphere at 1,000-1,500°C to nitride the silicon powder as much as 90% or more of the nitriding ratio, and further firing the nitride in a non-oxidating atmosphere contaning nitogen. COPYRIGHT: (C)2004,JPO