AlN焼結体の熱伝導率に及ぼす微構造の影響

概要

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The high thermal conducting mechanism of AIN ceramics has been investigated by the relationship between microstructure and thermal conductivity of the samples which were obtained by pressureless-sintering at 1900℃ for 1-24 h with Y_2O_3 2 at% addition as a sintering aid. The thermal conductivity increased gradually with increasing sintering time from 199 W/m・K at 1 h to 266 W/m・K at 24 h. Microstructure was investigated by SEM, TEM and powder X-ray diffraction together with quantitative analysis of Y and O contents. ain grain size increased from 4 μm at 1 h to 12 μm at 24 h and the grain boundary phase gradually concentrated to triple points and the amount of this phase decreased with sintering time. Furthermore, grain boundary phase composition changed from Al_2Y_4O_9(Al_2O_3・2Y_2O_3) at 1 h to Y_2O_3 at 24 h. This change seems to occur through selective reduction and notarization of Al_2O_3 in Al_2Y_4O_3 with an increase in sintering time. These results show that the decrease in phonon scattering at grain boundaries improves the thermal conductivity.
社団法人日本セラミックス協会の論文
1989-12-01