Paper number 606

OXIDE/OXIDE COMPOSITE FIBERS FOR ENHANCED CREEP RESISTANCE

Vincent H. Hammond, Frank E. Wawner, and Dana M. Elzey

Department of Materials Science and Engineering, University of Virginia,
Thornton Hall, Charlottesville, Virginia, 22903, USA

Summary

Aluminum oxide multi-filament tows may be produced at relatively low cost, but are limited by poor creep strength at elevated temperatures. This study compares the creep behavior of alumina tow-fibers with that of recently developed oxide/oxide CMC fibers. The CMC fibers tested were fabricated by infiltration of an alumina tow with an alumina powder slurry, followed by outgassing and sintering. The resulting alumina matrix is highly porous (roughly 50% of theoretical density), but is found to exert a strong influence on the fiber's mechanical properties. While uniaxial creep tests conducted at 1100ºC revealed similar creep stress exponents (of around three) for both plain and CMC fibers, the composite fibers exhibited dramatically improved failure strains and time-to-failure. The origins of this enhanced creep behavior are discussed in terms of the composite fiber architecture and sintering treatment.

Keywords

tow-fiber, alumina, oxide/oxide composite, creep.