The manufacture of partially-stabilised and fully-stabilised zirconia fibres blow spun from an alkoxide derived aqueous sol-gel precursor

Aligned fibres of partially stabilised zirconia (PSZ, 4 mol% Y2O3) and fully stabilised zirconia (FSZ, 8 mol% Y2O3), 3-5 mum in diameter, were blow spun from a sol-gel precursor, and then fired to give the ceramic fibre. Various potential sol precursors were investigated and characterised, the optimum being an aqueous sol made from hydrolysed and peptised zirconium iso-propoxide. The resulting zirconia fibres were characterised and their evolution studied by XRD, DTA/TGA and SEM, and their mechanical properties assessed. It was found that both PSZ and FSZ fibres formed poorly crystalline cubic zirconia at only 200 degreesC, which became fully crystalline after firing to 400 degreesC. The cubic form was the only phase seen in the FSZ fibre, whereas the PSZ fibre formed the tetragonal phase after firing between 1000 and 1200 degreesC/3 h, and all fibres were nanocrystalline (grain diameter m). Unusually the monoclinic form of zirconia was never observed in the PSZ fibres. After firing above 1200 degreesC the fibres had a strain to break of 0.59%, and appeared to be well sintered from shrinkage data, They had superior creep resistance to Saffil zirconia fibres, creeping at temperatures 50 degreesC higher. (C) 2000 Elsevier Science Ltd. All rights reserved