異なる添加物を含む窒化ケイ素セラミックスの熱伝導率に及ぼす焼結後熱処理の影響

概要

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Silicon nitride ceramics were fabricated by dry pressing of a raw α-Si_3N_4 powder with Y_2O_3-SiO_2 and Y_2O_3-Al_2O_3 as sintering aids, following by gas-pressured sintering at a temperature of 2123K for 2h under a nitrogen gas pressure of 1.0MPa with Si_3N_4/BN packing powder. Subsequently, these specimens were heat-treated at a temperature up to 2223K for 8h under a nitrogen gas pressure of 1.0MPa without any packing powder. Mass loss, density, oxygen content and thermal conductivity of the specimens before and after the post-sintering heat-treatment were measured. Due to the heat-treatment, the reduction of oxygen content, via the reaction of Si_3N_4 and SiO_2, without decrease of relative density was found to be effective in improving thermal conductivity of the Si_3N_4 ceramics sintered with Y_2O_3-SiO_2 additives. The effect of post-sintering heat-treatment was not significant for the Si_3N_4 specimen sintered with Y_2O_3-Al_2O_3 additives due to formation of SiAlON. Thermal conductivity of one of the former specimens reached 84W/m・K at room temperature.
社団法人日本セラミックス協会の論文
2005-06-01