Y_2O_3添加AINの熱伝導率に関する粒成長誘起型急変モデル

概要

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A theoretical model is proposed for explaining the increase in thermal conductivity experimantally found upon annealing in an AIN polycrystal doped with ≈3 vol% Y_2O_3. The model foresees the concurrent effect of the growth of AIN-matrix grains and of the collapse of grain boundaries filled by the low thermal conductivity Y_2O_3 phase. Such depleted grain boundaries form directly bonded two-grain junctions. Grain growth produces a reduction of scattering of phonons at grain boundaries, and the increase of the number of directly bounded grain bondaries increases the average size of the thermally conductive AIN clusters. Thus both the phenomena accompanying the microstructural evolution can lead to an increase of thermal conductivity in the polycrystal. The mathematical formulations of phonon scattering at grain boundaries and the percolation model are revisited and rearranged to give a comprehensive model of grain-growth-assisted percolation, which links the microstructural evolution of the polycrystal to the experimentally observed increase in its thermal conductivity.
社団法人日本セラミックス協会の論文
1999-10-01