MULLITE (3AL(2)O(3)-2SIO(2)) SYNTHESIS WITH ALUMINOSILOXANES

High-yield mullite (3A1(2)O(3)-2SiO(2)) precursors consist of aluminos iloxanes :synthesized from mixtures of aluminum arid silicon alkoxides . Atomic level mixing of the aluminum and silicon oxides is demonstrat ed by the low-temperature conversion (< 1000 degrees C) of the alumino siloxanes to phase-pure mullite. The proper selection of monomeric sid e groups serves several functions: (i) controlling reactivity of the s ilicon and aluminum monomers, thereby favoring atomic-level mixing; (i i) maintaining the tractability of the resulting aluminosiloxane; (iii ) improving the yield during mullitization of the aluminosiloxane thro ugh easy thermolytic removal. The tractability of the aluminosiloxane compounds permits these materials to be used, in fiber spinning, the c asting of thin films and monoliths, and as impregnants to powder compa cts.