"Preparation of Dense Mullite Ceramics and Their Properties"

"Dense and single-phase mullite polycrystals were prepared by reaction sintering of relatively pure kaolins with α-alumina. Removal of coarse kaolin particles > 1μm by sedimentation substantially improved thermal reactivity and sinterability of kaolin and its mixtures with alumina. As for mixtures of calcined kaolin and submicron corundum powder having a mullite composition, relative densities of above 99% were accomplished by heat-treatment at 1650°C for l h. Effect of preparation process on microstructure of sintered mullite ceramics was investigated, and the resultant mullite ceramics were consisted of uniform fine-grained mullite polycrystals. Higher 3-point bending strength than 350MPa was attained by utilizing calcined fine kaolin and submicron corundum powders.