Aluminosilicate formation in various mixtures of tetra ethyl orthosilicate (TEOS) and aluminum nitrate (ANN)

Reaction between different mixtures of tetra ethyl orthosilicate and aluminum nitrate nonahydrate at varying conditions have been studied by DTA technique. The result reveals that the two components react with the exhibition of an exotherm at ∼110 °C. During isothermal heating at ∼80 °C mixtures show rise in temperature with vigorous evolution of NO2 fumes and form gels those on heating to ∼500 °C form aluminosilicate precursor phase. The composition of it may be close to the approximate composition of mullite.