酸化物助剤添加量が窒化ケイ素の焼結および焼結体の高温特性に及ぼす影響

概要

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The effect of the amount of added oxide on the gas-pressure sintering behavior of silicon nitride and high-temperature properties (strength and oxidation resistance) of the sintered materials were investigated. Si_3N_4 containing 0.5 mol% (SN05) to 10% (SN10) of equimolar Y_2O_3-Nd_2O_3 was fired at 1900℃ for 4 h in 10 MPa N_2 gas. A small amount of the oxide (1 mol% ; SN1) was effective for densification as well as larger amounts of the oxide (6〜10 mol%). Composition analysis of the sintered specimens indicated that SN1 densified through a small amount of SiO_2-rich liquid phase, whereas SN10 densified by a large amount of additive oxide-rich liquid phase. SN1 had higher strength than SN10 at higher temperatures because of its smaller amounts of glassy phase. SN1 also had an excellent oxidation resistance because the composition lied in the Si_3N_4-Si_2N_2O-Y_2Si_2O_7 compatibility triangle, where Si_2N_2O and Y_2Si_2O_7 were stable with regard to oxidation.
社団法人日本材料学会の論文
1992-02-15