Abstract: Mullite porous ceramics were prepared by in-situ sintering using zirconia-containing sillimanite as the main raw material,α-Al₂O₃ powder as the auxiliary material and modified starch as the pore-forming agent.The effects of the sintering temperature (1 400-1 600 ℃,an interval of 50 ℃) on the phase composition,the microstructure and the properties of the samples were studied.The results show that:(1)with the increase of the sintering temperature,the intensity of the mullite diffraction peaks increases and the mullite crystals gradually grow up;moreover,steps are observed on mullite surfaces,indicating that the mullite grows by two-dimensional nucleation mechanism;(2)with the increase of the sintering temperature,the bulk density of the samples decreases firstly and then increases,while the apparent porosity and the linear change show the opposite trends,but the cold compressive strength increases gradually;(3)when the sintering temperature is 1 550-1 600 ℃,the samples show the optimal comprehensive properties;mullite crystals grow up and combine closely,which makes mullite porous ceramics suitable for application at high temperatures.

Key words: sillimanite, mullite, porous ceramic, sintering temperature, growth mechanism

摘要： 以含锆硅线石为主要原料,α-Al₂O₃粉为辅料,改性淀粉为造孔剂,原位烧结制备了莫来石多孔陶瓷试样。研究了烧结温度(1 400~1 600 ℃,间隔50 ℃)对试样物相组成、显微结构及性能的影响。结果表明:1)随烧结温度的升高,试样中莫来石衍射峰的强度逐渐增强,莫来石晶粒逐渐发育长大,其外观呈现明显的台阶状形貌,符合二维成核生长机制。2)随烧结温度的升高,烧后试样的体积密度呈先减后增趋势,而显气孔率和线变化率的变化趋势则与之相反,常温耐压强度则呈逐渐增大趋势。3)当烧结温度为1 550~1 600 ℃时,试样综合性能较佳,莫来石晶粒发育长大并致密结合,适于在高温下使用。

关键词: 硅线石, 莫来石, 多孔陶瓷, 烧结温度, 生长机制