Chakraborty, Akshoy Kumar (2003) Preliminary study on the effect of pH on thermal transformation of some diphasic Al2O3-SiO2 gels. Journal of Sol-gel Science and Technology, 28 (1). pp. 87-95. ISSN 0928-0707

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Abstract

Diphasic Al2O3-SiO2 gels have been synthesized by hydrolyzing ethyl orthosilicate at three different pH ranges in presence of colloidal boehmite. Result shows that dominant mullitization process are sensitive to pH of the gelation process. At highly acidic pH range, solid state reaction between corundum and cristobalite occurs, and develops liquid phase for mullite nucleation. At moderately acidic pH, nucleation and crystallization are most operative for nucleation in aluminosilicate matrix. In highly basic pH region, Al-Si spinel phase develops by incorporation of Si in aluminous phase as intermediary phase. Polymorphic transformation of it may be the cause of sudden mullitization. The changes in crystallization sequence in three distinct processes may be due to variation in the nature and size of silicic acid particle formed by hydrolysis and condensation of TEOS at different pH.

Item Type:	Article
Uncontrolled Keywords:	Diphasic Al2O3-SiO2 gel; pH variation; Aluminosilicate phase; Mullite; Gelation mechanism
Subjects:	Engineering Materials
Divisions:	UNSPECIFIED
Depositing User:	Subhra Lahiri
Date Deposited:	14 Feb 2012 11:54
Last Modified:	14 Feb 2012 11:54
URI:	http://cgcri.csircentral.net/id/eprint/833

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