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以九水硝酸铝和正硅酸乙酯为原料,以无水乙醇为溶剂,用溶胶-凝胶法制备出分子级均匀混合的莫来石前驱体。热重-差示扫描量热、X射线衍射和红外分析结果表明:前驱体在985℃直接由非晶态转化为富铝莫来石晶体,没有经历尖晶石相变过程,随着热处理温度的提高,富铝莫来石逐渐转化为结构为3Al2O3·2SiO2的稳定莫来石。前驱体粉末经1000℃煅烧4h后,用放电等离子烧结技术在1450℃烧结10min能制成透明莫来石陶瓷。
The molecularly homogeneously mixed mullite precursors were prepared by sol-gel method using anhydrous aluminum nitrate as solvent and aluminum nitrate nonahydrate and orthosilicate as raw materials. The results of thermogravimetry-differential scanning calorimetry, X-ray diffraction and infrared spectroscopy showed that the precursor transformed from amorphous state to aluminum-rich mullite crystal directly at 985 ℃ without experiencing spinel phase transformation. With the increase of heat treatment temperature , The Al-rich mullite gradually transformed into stable mullite with the structure of 3Al2O3.2SiO2. The precursor powder was calcined at 1000 ℃ for 4h, then sintered by spark plasma sintering at 1450 ℃ for 10min to produce transparent mullite ceramics.