Modelling the effect of oxidation on the creep behaviour of fibre-reinforced ceramic matrix composites

A creep-oxidation model is presented for continuous fibre-reinforced ceramic matrix composites at high temperature. The model includes the effects of interface and matrix oxidation, creep of the fibres and degradation of fibre strength with time. In particular, the influence of the glassy phases resulting from the oxidation of certain types of SiC based matrices is discussed. Model predictions are presented for the case of a woven Hi-Nicalon(TM)/SiC composite and compared to experimental results at 1000 and 1100 degreesC. The fraction of broken fibres increases with time in an accelerated manner as a result of load transfer and fibre degradation. The model also predicts that a fraction of broken fibres of about 15% triggers the unstable failure of the composite. (C) 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.