Dehydration and Crystallization Kinetics of Zirconia‐Yttria Gels
Dehydration and Crystallization Kinetics of Zirconia‐Yttria Gels
复制标题
氧化锆-氧化钇凝胶的脱水和结晶动力学
DOI：
10.1111/j.1151-2916.1995.tb08819.x
复制
发表时间：
1995
影响因子：
3.9
通讯作者：
K. Nayar
中科院分区：
文献类型：
--
作者：
S. Ramanathan;R. V. Muraleedharan;Sujit Roy;K. Padmanabha;K. Nayar
采用共沉淀法，在373K下烘干得到了含4%和8%Y的氧化锆凝胶和氧化锆-氧化钛凝胶，并用DSC、TG和X射线衍射仪研究了干凝胶的脱水和结晶行为。凝胶在373-673K的较宽温度范围内发生脱水，脱水吸热峰温度和脱水过程的动力学常数不受凝胶中氧化钇含量的影响。观察到的脱水热与汽化热数据符合得很好。脱水之后是一个急剧的放热结晶过程。随着氧化钇含量的增加，该过程的放热峰温度和活化能增加，而结晶热降低。随着氧化钇含量的增加，发光效应减弱。纯氧化锆析晶为四方晶型，而含4%和8摩尔%氧化钛的氧化锆晶相为立方晶型。
Zirconia and zirconia-yttria gels containing 4 and 8 mol % yttria were obtained by coprecipitation and drying at 373 K. The dehydration and crystallization behavior of the dried gels was studied by DSC, TG, and XRD. The gels undergo elimination of water over a wide temperature range of 373–673 K. The peak temperature of the endotherm corresponding to dehydration and the kinetic constants for the process were not influenced by the yttria content of the gel. The enthalpy of dehydration observed was in good agreement with the heat of vaporization data. The dehydration was followed by a sharp exothermic crystallization process. The peak temperature of the exotherm and the activation energy of the process increased with an increase in yttria content, while the enthalpy of crystallization showed a decrease. The “glow effect” reduced with increasing yttria content. Pure zirconia crystallizes in the tetragonal form while the zirconia containing 4 and 8 mol% yttria appears to crystallize in the cubic form.