以无水三氯化铝和正硅酸乙酯(TEOS)为反应前驱体,无水乙醚为氧供体,采用非水解溶胶一凝胶法低温合成莫来石粉体。借助DTA-TG、XRD、FF-IR、TEM等测试手段研究回流工艺、氧供体加料顺序、氧供体用量对莫来石合成效果的影响,探讨了莫来石千凝胶粉在热处理过程中的相变化及低温合成莫来石的反应机理。结果表明:回流工艺有助于莫来石的合成;采取AlCl3与TEOS先混合,再引入氧供体的加料顺序效果好,并且氧供体的最佳用量为0.52L/lmolTIOS;采用乙醚为氧供体制备的莫来石凝胶为单相凝胶,在800℃即开始出现莫来石,900℃莫来石晶相已发育良好,溶胶~凝胶反应过程中形成的A1-O-si异质聚合是低温合成高纯莫来石粉体的关键。
Mullite powder has been synthesized at low temperature via non-hydrolytic sol-gel method using anhydrous aluminium chloride and ethyl silicate as precursors, and ether as oxygen donors. The effect of reflux gelation process, addition order and quantities of oxygen donors on the synthesis of mullite powder were studied; the phase transformation of mullite xerogels during the heat treatment and the reaction mechanism of low temperature synthesis of mullite via non-hydrolytic sol-gel method were also investigated by means of FT-IR, DTA-TG, XRD, TEM, etc. The results indicate that reflux gelation process is favorable for the synthesis of mullite. When oxygen donor is introduced into the AICI3-TEOS mixture solution, the better synthesis effect happens, and the optimal quantity of oxygen donor is 0.52L/1mol TEOS. The mullite xerogel, prepared using ether as oxygen donor through the reflux process, belongs to single-phase gel. Mullite crystal phase has begun to appear at 800℃, and well-developed at 900℃. The formation of bond during the sol-gel reaction process plays the key role in the low temperature synthesis of high purity mullite powder.