Sol–gel processing of alumina fibres

Alumina fibres were prepared by sol–gel process. The sol was prepared by mixing aluminium-tri-isopropoxide in distilled water and refluxed in the presence of acid catalyst. Binder was added in different amount to the sol to obtain spinnability. At the appropriate viscosity, the sol was taken in a syringe and fibres were drawn in the ammonia solution. The fibres were dried at room temperature and then sintered at 1600 °C for 2 h, α-alumina is the only phase present in the sintered fibres. Differential thermal analysis indicated that the phase transition to α-alumina takes place at 1100 °C. Thermogravimetric analysis indicated the removal of most of the volatile up to 600 °C. Scanning electron microscopic analysis reveals dense microstructure is formed with 10 wt.% hydroxyl ethyl cellulose. The tensile strength is found to be good for sample containing 10 wt.% hydroxy ethyl cellulose.