Novel Synthesis of Mullite Powder with High Surface Area

Boehmite (AlO(OH)) solid-solution gel, which yields stoichiometric mullite (3Al 2 O 3 .2SiO 2 ) at high temperatures, has been prepared by the hydrazine method. The formation process leading to 3Al 2 O 3 .2SiO 2 is discussed. The asprepared powder and powders heated below 1200°C consist of very fine particles showing needlelike morphology, whereas the particles of mullite powder show thin prismatic morphology. The mullite powder after heating at 1300°C has a high surface area (87 m 2 /g).