Influence of Clay Materials on Acicular Mullite Porous Ceramic

Porous acicular mullite ceramic was prepared by in-situ reaction sintering, using clay materials and Al(OH)(3)) as the raw materials. The influences of different clay materials on the phase composition, formation of acicular grains and microstructure of prepared porous ceramics were investigated. Results show that the metal oxide impurities were beneficial for the synthesis of acicular mullite. The prepared porous ceramic from Longyan kaolin with high impurity content has the highest mullite content of 93.5%, and composed of interlaced acicular grains with high slenderness ratio of 26.4 and large average diameter of about 0.7 mu m when sintered 1400 degrees C for 2h. The TEM analysis indicates that the growth direction of acicular grains is along the [001] direction (c axis) of orthorhombic mullite crystals.