表面状態の異なる3mol% Y_2O_3-ZrO_2 セラミックスの熱水中における正方晶から単斜晶への転移速度の違い

概要

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Hot-isostatic-pressed(HIP'd)tetragonal zirconia ceramic containing 3 mol% Y_2O_3 was soaked in hot water at 95-100℃ to evaluate the transformation rate from the tetragonal(T)to the monoclinic(M)phase. The transformation rate differed considerably between the polished surface and the surface cut by a diamond wheel. After about 1000 h of soaking in hot water, the volume of thc M-phase was 50% in the cut surface and less than 20% in the polished surface. Tetragonal ZrO_2 with polished and cut surfaces were annealed at 1000°C for 2h in air. When the annealed specimens were soaked in hot water, the transformation rate in the cut surface was the same as that before annealing ; on the other hand, the M-phase volume in the polished surface increased to 70% after 1000 h of soaking. Surface roughness, a rhombohedral phase generated by cutting or machining and orientation of the T-phase crystal due to machining, are thought to be causes of the transformation rate change. However, not one of them on its own could explain all the phenomena without contradiction.
社団法人日本セラミックス協会の論文
1999-01-01