HIGH-TOUGHNESS AND HIGH-STRENGTH SILICON NITRIDE SINTERED BODY AND SILICON NITRIDE STRUCTURAL MEMBER MANUFACTURED BY ATMOSPHERIC PRESSURE SINTERING WITHOUT USING RARE EARTH ELEMENT AND METHOD FOR MANUFACTURING SAME

摘要

The present invention relates to a high-toughness high-strength silicon nitride sintered body and a silicon nitride structural member manufactured by an atmospheric pressure sintering process which does not use a rare earth element. The crystal phase of silicon nitride is not less than 88 wt%, and a rare earth element or rare earth compound is not contained as a sintering aid. 1.5-4 wt% of Mg element converted to oxide, 0.5-2.5 wt% of Al element converted to oxide, 1-5 wt% of Ti element converted to oxide, and 1-4.5 wt% of Si element converted to oxide are contained necessarily as sintering aids. The weight ratio of Al element converted to oxide to Mg element converted to oxide is in the range of 1:1 to 1:2.5, the weight ratio of Al element converted to oxide to Si element converted to oxide is in the range of 1:1 to 1:3, and the weight ratio of Al element converted to oxide to Ti element converted to oxide is in the range of 1:1 to 1:4.5.;COPYRIGHT KIPO 2018