Synthesis of Mullite Precursor Powder in Diphasic Gel Form

Mullite powder precursor in the form of diphasic Al2O3-SiO2 gel was prepared by sol-gel route following reverse addition technique using fume silica and aluminium nitrate nonahydrate as starting materials. The precursor powder prepared was calcined at different temperatures and thoroughly characterized. Thermal decomposition behaviour of produced mullite powder precursor was studied by means of TG-DSC analysis. Phase analysis of calcined powder at different temperatures was done by XRD study. Nature of different bonds present in the precursor powder and calcined powders were analysed by FTIR study. Finally the morphology of the powder precursors and their modification during heat treatment was observed by SEM. Here the desired mullite phase is formed at 1300 degrees C through the formation of alumina intermediate phases.