Page 115 - Fiber Fracture

100 M.-H. Berger

Fig. 14. Detail of a fracture surface of the PRD 166 fibre composed of alumina, in dark and zirconia, in
bright.

Fig. 15. Crack propagation in a zirconia-reinforced alumina fibre, the PRD 166 fibre, broken at room
temperature after creep test at 10o0"C. Zirconia darker grains around the crack are twinned.

efficient as the temperature exceeds 1100°C. At 1300°C the creep rates as well as the
failure modes of FP and PRD 166 fibres are similar.
A flexible a-alumina-zirconia fibre, Nextel 650 fibre, has been recently developed by
3M, with the aim of increasing the creep resistance with respect to that of the a-alumina
Nextel 610 fibre. Its smaller diameter and grain sizes, when compared to PRD 166
fibre, give rise to a flexible fibre and 3M reports high strength (2.5 GPa at 25 mm). As