ChemInform Abstract: Preparation of Mullite Cordierite Composite Powders by the Sol‐Gel Method: Its Characteristics and Sintering.

Abstract

002ChemInform Abstract Mullite (3 Al2O3•2 SiO2)/cordierite (2 MgO•2 Al2O3•5 SiO2) composite powders containing up to 60 wt.% cordierite (M/C 60) are prepared by the sol-gel process using boehmite, colloidal silica, and Mg(NO3)2 as starting materials. For M/C 10, crystallization of mullite and cordierite is not observed (formation of a MgO-mullite solid solution), while these phases are detected as the only phases present in M/C 40 composites sintered at 1450 rc C. The sintered density of all composites increases with increasing temp. up to 1450 rc C and then decreases. The flexural strength decreases with increasing cordierite content. The room temp. flexural strength of M/C 40 is 300 MPa and is maintained up to 1200 rc C. A thermal shock resistance of 375 rc C is observed for M/C 40 and, therefore, this material may be useful for engineering applications that require high thermal shock resistance and low thermal expansion.