| abstract |
A process for preparing mullite, 3Al 2 O 3 .2SiO 2 , whiskers by n (1) forming an intimate, anhydrous mixture of AlF 3 and SiO 2 powders in about a 12:13 molar ratio; n (2) heating the mixture in an anhydrous, SiF 4 atmosphere at about 700° C. to about 950° C. to form barlike crystalline topaz, Al 2 (SiO 4 )F 2 ; and n (3) heating the barlike crystalline topaz under anhydrous conditions in a SiF 4 atmosphere at a temperature of from about 1150° C. to about 1400° C. to produce mullite whiskers. n The mullite whiskers produced can be used in ceramic and metal matrices without further chemical treatment. |