Effect of MgSiN_2 addition on gas pressure sintering and thermal conductivity of silicon nitride with Y_2O_3(<Feature>SiAlons and Non-oxides)

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This paper reports the gas pressure sintering and thermal conductivity of silicon nitride with 2 mol% Y_2O_3 and varied contents of MgSiN_2 in the range of 0 to 5 mol% at 1900℃ under a nitrogen pressure of 1 MPa N_2. It was found that the density curves show a typical "V" shape against the MgSiN_2 content. The 1 mol% MgSiN_2 hinders significantly the densification, but the 5 mol% MgSiN_2 leads to complete densification. The inhibited densification is associated with the pronounced normal grain growth. However, the abnormal grain growth is inhibited with the addition of MgSiN_2. After sintering for 12 h, the sample without MgSiN_2 exhibits the coarsest and highest bimodal microstructure, whereas the one with 5 mol% MgSiN_2 exhibits the finest microstructure. Although the MgSiN_2 addition leads to a slightly enhanced thermal conductivity, it tends to reduce the thermal diffusivity. The thermal conductivity without porosity shows a decrease with the increase of MgSiN_2 content because of the inhibited grain growth.
社団法人日本セラミックス協会の論文
2008-06-01