3 mol% Y2O3-ZrO2 セラミックスにおける相分離と水熱劣化
3 mol% Y2O3-ZrO2 セラミックスにおける相分離と水熱劣化
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3 mol% Y2O3-ZrO2 陶瓷中的相分离和水热降解
DOI：
10.2109/jcersj.113.530
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发表时间：
2005
影响因子：
1.1
通讯作者：
孝次 津久間
中科院分区：
文献类型：
--
作者：
勲 山下;孝次 津久間
通过 X 射线衍射法研究了 3 mol% Y2O3 稳定的四方 ZrO2 多晶 (3Y-TZP) 中的相分离和水热降解。 Rietveld分析表明，高温下烧结体的晶体结构发生显着变化。随着烧结温度的升高，烧结体相分离为高钇区和低钇区。两个区域都属于四方相。高钇区域可以使用c/a≒1的四方相模型进行分析。水热降解引起的单斜相的量随着降解时间的增加而增加。利用Johnson-Mehl-Avrami方程分析了四方相到单斜相变的老化动力学。用该方程评估的可转变相的分数与用Rietveld 分析确定的低钇区域的分数非常一致。定量分析清楚地表明，低钇区域在热液条件下选择性地转变为单斜晶相，而高钇区域则没有转变。 3Y-TZP 陶瓷在水热条件下的可转变分数由低钇区域的量决定。由于相分离而形成低钇区域是烧结体中水热降解的原因。
Phase separation and hydrothermal degradation in 3 mol% Y2O3-stabilized tetragonal ZrO2 polycrystal (3Y-TZP) were studied by X-ray diffractometry. The Rietveld analysis showed that crystal structure of sintered body remarkably changes at high temperature. The sintered body is phase separated into high and low yttrium region with increasing sintering temperature. Both regions are assigned to the tetragonal phase. The high yttrium region can be analyzed using tetragonal phase model with c/a≒1. The amount of monoclinic phase induced by hydrothermal degradation increased with increasing degradation time. Aging kinetics of tetragonal to monoclinic phase transition was analyzed with Johnson-Mehl-Avrami equation. Fraction of transformable phase evaluated with the equation is in good agreement with the fraction of low yttrium region determined with the Rietveld analysis. The quantitative analyses clearly show that the low yttrium region selectively transforms into monoclinic phase under the hydrothermal condition, while the high yttrium region does not transform. Transformable fraction during the hydrothermal condition in 3Y-TZP ceramics is governed by the amount of low yttrium region. The formation of low yttrium region due to phase separation is responsible for hydrothermal degradation in sintered body.