Transactions of the INDIAN CERAMIC SOCIETY Vol. 56 1997
Solvent Interactions on the Gelation Characteristics
of Sol-Gel Mullite Precursors and their Effect
on High Temperature Behaviour
G. M. ANILKUMAR, P. MUKUNDAN AND K. G. K. WARRIER
Pages : 79-81
DOI : 10.1080/0371750X.1997.10804798
Abstract
An attempt has been made to prepare stoichiometric mullite
powders by mixing aluminium nitrate and TEOS in
diffet·ent solvents like distilled water, ethanol and methanol.
The sol obtained was spray dried and the powders were
calcined in the range 850-lOOOC and sintered at 1600C.
XRD patterns of these powders calcined at lOOOC showed
mullite formation in all the solvent systems. Thermal
analysis data indicated mullite exotherm below lOOOC. A
10% increase in density was observed on sintering at 1600C
preferentially for methanol derived powder. Fractographs of
the sintered mullite generally showed localised densification
indicating the inhomo-geneity in the precursor. A controlled
hydrolysis of the precursor under different solvent media
was indicated to influence the gelation characteristics and
bring down the extent of inhomogeneity. A correlation has
been presented with respect to history of gelation and the
formation of a mullite phase as well as development of
sintered microstructure.
