不同干燥过程对超细TiO2粉体性质的影响

考察了采用不同干燥工艺制备的TiO2粉体在粒子形貌、颗粒大小与分布、晶相组成以及比表面积和孔结构等织构和结构性质方面的差异。结果表明，利用常规的干燥方法，由水凝胶脱水所得的颗粒，颗粒间严重团聚，颗粒粒径大且分布不均匀，比表面积和孔体积最小；由醇凝胶直接脱水，则可以显著提高粉体的织构性能．而采用超临界流体干燥法则可以进一步提高粉体的性能，比表面积由水凝胶的4．88m2·g－1增大到113．8m2·g－1，提高了近30倍；孔体积由0．027cm3·g－1增大到0．41cm3·g-1．大约提高了15倍；而且其能够有效地防止粒子间的团聚，较好地保持了湿凝胶的网络结构，使颗粒尺寸降低且分布均匀，可重复性好．

Effects of Different Drying Methods on the Properties of TiO_2 Particles

The effects of different drying methods on the properties of TiO2 powders have beenstudied. Usually in the case of conventional drying. varions forces mainly in the form of capillarypress cause differential macroscopic and microscopic shrinkage and the gel structure cracks, sothe specific surface areas and pore volumes are small for hydrogel or alcolgel prepared. Thesupercritical fluid drying (SCFD) can eliminate any liquid-vapor interface inside the gel duringsolvent extraction. so avoiding the macroscipic or microscopic collapse and preserving the structureof the wet gel. so the specific surface areas and pore volumes of aerogel botaied has the largestvalues.These ultrafine powders prepared by the supercritical drying have reproductive high surfaceareas and large pore volumes.