Investigation of Aluminosilicate Crystallization behavior in SiO2-Al2O3 System

The aim of this study is to achieve a monophasic mullite (3????????2????3.2????????????2), with stoichiometric ratio of (3:2) and non-stoichiometric ratios of (2: 1) and (3: 4) by sol-gel method. Tetraethylorthosilicate (TEOS) and aluminum nitrate nonahydrate (ANN) were used as main ingredients. After gelation process, all the samples were aged at ambient temperature for 17 days and then dried at two different temperatures. All prepared samples were heat treated at temperatures ranging from 600-1550 °C and cooled in the furnace. Heat treated samples were characterized with XRD analysis to identify the crystalline phases. SEM and FTIR analysis were also performed to evaluate the morphology and chemical configuration of crystalline phases, respectively. In stoichiometric samples and non-stoichiometric specimens with higher alumina content, the needle morphology of mullite were observed.