Sol–gel based extrusion of alumina–zirconia fibres

Alumina–zirconia fibres were prepared by sol–gel process. The starting materials used for the preparation of alumina and zirconia sol were aluminium-tri-isopropoxide and zirconium oxychloride, respectively. Alumina sol and zirconia sol were mixed in definite proportions, so that the final composition contains 10 wt.% ZrO2. Fibres were drawn from the gel using an extruder and dried at room temperature and subsequently sintered at 1200, 1400 and 1600 °C. Differential thermal analysis showed that α-Al2O3 phase transition occurs at 1290 °C. The phases present in the sintered fibres were α-Al2O3, t-ZrO2 and m-ZrO2. Scanning electron microscope revealed dense microstructure is formed at 1600 °C. Tensile strength was found to be the highest for fibres sintered at 1600 °C.