SiO_2-MgO-Y_2O_3助剤添加窒化ケイ素セラミックのつめ粉不使用低温無加圧焼結

概要

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Si_3N_4 ceramics were sintered at 1873-2023K (1600-1750℃) with additives from the SiO_2-MgO-Y_2O_3 system. The degree of densification, α-β transformation, mass loss and microstructure were measured as a function of additives composition, sintering temperature, nitrogen gas pressure, and with/without packing powder. Specimen prepared from 3 mass% SiO_2, 3 mass% MgO, and 5 mass% Y_2O_3 as the sintering additive could be sintered to almost full density at relatively low temperature as 1923K for 2h under ambient pressure of nitrogen atmosphere without using packing powder. The α-β transformation was not completed at this condition. The mass loss was relatively high due to the evaporation of SiO_2 and MgO. However, the resulted materials have high bending strength as 980MPa, with fracture toughness of 6.6MPa・m^<1/2>, Vickers hardness of 18.4GPa, and thermal conductivity of 34Wm^<-1>K^<-1>.
社団法人日本セラミックス協会の論文
2006-09-01