比表面积对TiO2陶瓷烧结初期致密化行为的影响

Effect of Specific Surface Area on the Densification Behavior of TiO_2 Ceramics at the Initial Sintering Stage

将比表面积分别为30m^2／g和1m^2／g的纳米（50nm）和微米（2μm）金红石TiO2陶瓷坯体在高温热膨胀仪中自室温至1200℃进行恒速无压烧结，升温速率为1℃／min，3℃／min和5℃／min，热膨胀仪自动记录烧结收缩。为阐明比表面对无压烧结初期致密化行为的影响，研究了氧化钛陶瓷的烧结收缩行为。同时，利用Arrhenius曲线研究了纳米和微米氧化钛陶瓷的烧结激活能。结果表明：随烧结温度的增加，比表面积的增加加速了致密化速率；纳米和微米氧化钛的烧结激活能分别为115±10kJ／mol和302±15kJ／mol；对于纳米氧化钛，当烧结体的瞬时相对密度为70～80％时，出现最大致密化速率，而对于微米氧化钛陶瓷，最大致密化速率出现在相对密度为75—85％。

The nanometer and micrometer futile TiO2 power compacts with and 1 m^2/g were sintered in air at 1200 ℃ at constant heating rates of 1 using a dilatometer. The shrinkage behaviors of TiO2 were investigated specific surface area of 30 m^2/g ℃/min, 3 ℃/min, 5 ℃/min to clarify the effect of specific surface area on the densification behaviors at the initial sintering stage. The apparent sintering activation energies were also investigated using the shrinkage data by the Arrhenius plot. The results show that the increase in specific surface area enhances the densification rate with increasing temperature. The activation energy values of nanometer and micrometer TiO2 are 115 ± 10 kJ/mol and 302 ±15 kJ/mol, separately. The effect of heating rates on densification rate for manometer TiO2 is much greater than that for micrometer TiO2. For nanometer TiO2, a maximum vale of densification rate appears when the instantaneous relative density is in the range of 70 - 80 %. But for micrometer TiO2, the maximum value of densification rate appears in the range of 75 - 85 %.