Synthesis of mullite powders using precipitated silica and tetraethoxy silane and aluminium-formate as precursor materials in aqueous medium

Abstract

Mullite (3Al₂O₃-2SiO₂) powder was prepared by using an aqueous sol-gel method where aluminium formate and tetraethoxy silane (TEOS) and precipitated silica were used as the precursor compounds and water was used as reaction medium instead of the conventionally used solvent alcohol. The gels were calcined at 1000°C, 1200°C and 1300°C for 1 h and characterized by X-ray powder diffraction, infrared spectroscopy, differential thermal analysis, thermogravimetry analysis and transmission electron microscopy. This method is shown to provide homogeneous, reactive amorphous powder at comparatively low temperatures.