Chakravorty, A K (1997) Further studies on thermal transformation of diphasic Al2O3-SiO2 gel. Transactions of the Indian Ceramic Society, 56 (1). pp. 9-15. ISSN 0371-750X

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Diphasic mullite gel (Si/Al=1/3) has been synthesized in.situ by hydrolyzing an aqueous solution of silica sol and aluminium salt with the help of NH4OH solution. It has been characterized by DTA. The formation of Si-Al spinel during non-eqilibrium heating of the gel and its subsequent transformation have been recorded by XRD technique. The result shows that Si—Al spinel crystallizes very slowly at 500°-800°C and then very rapidly at 1200°C which corresponds with the exhibition of a broad exotherm between 1100° and 1300°C in DTA. Accordingly, this exotherm is attributed to the formation of Si—Al spinel. It suddenly transforms to predominant amount of orthorhombic form of mullite with consequent exhibition of an exotherm at 1320°C in DTA. The residual non-crystalline aluminosilicate phase also crystallizes into mullite and accounts for the second mullitization process in diphasic gel.

Item Type: Article
Subjects: Engineering Materials
Depositing User: Bidhan Chaudhuri
Date Deposited: 25 Jul 2012 10:43
Last Modified: 12 Mar 2014 11:33

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