WANG Jianjun¹,SUN Feng ²,ZHUANG Yinghua ¹,LIAO Shenjun ¹,JIANG Changxi¹,WANG Zaiyi²,ZHOU Lijuan ¹
(1.School of Materials Science and Engineering,Shandong University of Technology,Zibo 255000,Shandong,China;2.Sinoma Advanced Nitride Ceramics Co.,Ltd.,Zibo255000,Shandong,China)

Abstract: The effect of Ho₂O₃ on phase composition, microstructure and thermal conductivity of silicon nitride ceramics was studied, in the form of ternaryMgO-Yb₂O₃-Ho₂O₃sintering aid, by adjusting the ratio of Yb₂O₃ and Ho₂O₃ (0 wt.%-6 wt.%). It was found that the type of secondary phases and the degree of crystallization of the ceramics are strongly dependent on the proportion of Ho₂O₃ in the ternary sintering aid. With increasing content of Ho₂O₃, the grain size of β-SisNa tends to be refined, which in turn resulted in increase in fracture strengthof the silicon nitride ceramics. The maximum fracture streng th was(802±15)MPa,while the fracture toughness was(7.62±0.12)MPa-ml2.Compared with Yb₂O₃Ho₂O₃is more likely to form glassy phase,reducing the degree of crystallinity and thermal conductivity of the sample.

Key words: MgO-Yb₂O₃-Ho₂O₃; ternary additive; thermal conductivity; fracture toughness