叔丁醇基凝胶注模工艺制备轻质、高强莫来石多孔陶瓷

以叔丁醇为成型溶剂, 莫来石粉为起始原料, 采用凝胶注模成型方法制备出轻质、高强莫来石多孔陶瓷. 莫来石多孔陶瓷中的孔隙形成于干燥过程中叔丁醇的快速挥发, 孔隙分布均匀且相互连通. 随烧结温度升高, 气孔率、开气孔率和比表面积分别由77.8%、76.0%和10.39m²/g下降到67.6%、65.5%和4.26m²/g, 而抗压强度则由3.29MPa显著提高到32.36MPa, 材料孔径大小受烧结温度影响较小, 孔径尺寸呈单峰分布, 且几乎所有的气孔都为开口气孔, 透气度与孔径尺寸具有一致的变化关系. 莫来石多孔陶瓷在高气孔率条件下仍然保持高强度的主要原因是材料中均匀的孔隙结构、孔径尺寸小且相对集中、以及因烧结颈的形成在空间上所表现出的一种颗粒搭接骨架结构.

Fabrication of Low Density High Strength Porous Mullite Ceramics by Tert-butyl Alcohol-based Gelcasting Process

Porous mullite ceramics with low density and high strength were fabricated by TBA-based gelcasting process using tert-butyl alcohol (TBA) as shaping solvent. The pores of porous mullite ceramics formed from the quickly evaporation of TBA during drying of green bodies. Uniformly distributed and interconnected pores were obtained. With increasing sintering temperature, the porosity, open porosity and specific surface area of porous mullite ceramics decrease from 77.8%, 76.0% and 10.39m²/g to 67.6%, 65.5% and 4.26m²/g, respectively, in contrast, the compressive strength significantly increases from 3.29MPa to 32.36MPa. The pore size is not significantly influenced by the sintering temperature. The pore size presents single peak distribution, and almost all pores are open. Air permeability is in accordance with the pore size. The reasons for high strength of porous mullite ceramics under high porosity are mainly due to the uniformly porous structure, small and relatively concentrated pore size, and the formation of sintering neck which shows a skeleton structure of particle bond in stereo-space.