Paper number 750


J.A. DiCarlo1 and H.M. Yun2

1,2Materials Division, NASA Glenn Research Center, 21000 Brookpark Road
Cleveland, OH 44135, USA

Summary This paper examines some of the key intrinsic and extrinsic factors that control the stress-rupture behavior of ceramic matrix composites (CMC). Because CMC rupture typically occurs simultaneously with the time-dependent fracture of the ceramic fiber reinforcement, emphasis is placed on elucidating the microstructural, environmental, and physical factors that control the low and high temperature rupture behavior of a variety of oxide and SiC-based fibers. Empirically determined Larson-Miller and Monkman-Grant rupture plots for these fibers are presented and discussed in terms of their basic and practical implications. Using composite theory, mechanical models are developed which show how the fiber data can also be used to understand and predict stress rupture behavior for cracked and uncracked CMC under some simple application conditions. Based on the good agreement observed between the model predictions and CMC results in the literature, some preliminary guidelines are presented for selecting constituents for optimum CMC rupture life.
Keywords oxide fibers, SiC fibers, rupture, creep, microstructure, oxidation, matrix cracking, rupture models.

Theme : Ceramic Matrix and C/C Composites

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