CeO_2对堇青石陶瓷的相组成和性能的影响

Effects of CeO_2 on the phase components and properties of cordierite ceramics

为了获得堇青石含量高且具有一定孔隙率的堇青石质耐火材料 ,用 X射线衍射仪、扫描电镜和热膨胀仪等手段研究了由氧化物粉末 (Mg O、Al2 O3 和 Si O2 )制备堇青石陶瓷时 ,添加 Ce O2 对堇青石陶瓷相组成和性能的影响 ,分析了 Ce O2 在烧结过程中的作用机理。试验表明 ,在 1370℃烧结 3h,该陶瓷由堇青石和孤立分布的玻璃相组成。随 Ce O2含量增加 ,陶瓷的致密度、弯曲强度和热膨胀系数逐渐升高。适量添加 Ce O2 (质量分数为 0 .0 2～ 0 .0 4) ,显著降低中间相(方石英、尖晶石 )的含量。Ce O2 的作用主要与改变 Si4+、Al3 +和 Mg2 +离子的扩散有关。这种工艺特别适用于制造窑具。

CeO 2 is used as an additive in the sintering of cordierite ceramic to obtain ceramics with highly amounts of cordierite and to decrease the sintering temperature. In the present work, the cordierite ceramics were prepared with powder sintering method. The effects of CeO 2 on the phase components and properties were studied using X-ray diffractometer, scanning electronic microscope and thermal-mechanical dilatometer. The mechanism of CeO 2 in sintering is also discussed. When sintered at 1370℃ for 3h, the ceramics are composed of cordierite and isolated glass phase. The density, bending strength and thermal expansion coefficient increase with increasing CeO 2 content. The ceramic added 0.02~0.04 (mass fraction) of CeO 2 is suitable for fabricating porous assemblies, such as filters for high temperature streams and catalytic supports for purifying vehicle exhaust. The action of CeO 2 is associated with the modification of cation diffusion in the sintering process.