Preparation of mullite fibres by sol-gel processes using aluminium carboxylates and tetraethylorthosilicate

Mullite fibres were prepared using aluminium carboxylates (ACs) and tetraethylorthosilicate by sol-gel process. ACs were synthesised from dissolution aluminium in a mixture of formic acid and glacial acetic acid using aluminium chloride hexahydrate as catalyst. The optimum condition for obtaining ACs is as follows: the molar ratio of aluminium, formic acid and acetic acid was 1 : 3 : 2.26 and aluminium chloride hexahydrate was 10 wt-%. All the Al and Si components were mixed at the molecular level and linear molecules were formed in the precursor sol. The dried gel fibres completely transformed to mullite fibres at 1200 degrees C and the calcinated fibres had a smooth surface and uniform diameter.