Activation energy of mullite crystallisation from precursor fibres determined by differential scanning calorimetry

Abstract

Mullite fibres were prepared by the sol–gel method using aluminium lactate and tetraethylorthosilicate. The aluminium lactate was prepared by mixing aluminium nitrate and lactic acid with a molar ratio of 1∶3. Thermogravimetry–differential scanning calorimetry, X-ray diffraction and scanning electron microscopy analysis were used to characterise the properties of the gel and ceramic fibres. The gel fibres completely transformed to mullite fibres at 1200°C, with a uniform diameter and dense microstructure. The active energy of mullite crystallisation was 1121·7 kJ mol⁻¹ by the Kissinger equation, which was consistent with most data reported by other authors.