PREPARATION OF MULLITE WHISKERS FROM AlF3, SiO2, AND Al2O3 POWDERS

摘要

A process for preparing mullite whiskers by (1) forming an anhydrous, intimate, uniform mixture of AlF3, Al2O3, and fused SiO2 powders in an amount selected to produce stoichiometric mullite or a solid solution of Al2O3 in stoichiometric mullite; (2) heating the mixture in anhydrous SiF4 atmosphere at a temperature of from about 700°C to about 950°C to form barlike topaz crystals; (3) heating the barlike topaz in an anhydrous SiF4 atmosphere at a temperature of from about 1150°C to about 1700°C to produce the mullite whiskers.