Fatigue Behaviour of Structural Ceramic Composites
Non-oxide composites are interesting materials for long term applications at high temperature under oxidizing atmosphere. To improve their lifetime, self-healing [Si-B-C] matrix has been developed recently. On this new generation of composite, fatigue has been studied at high temperature (up to 1200°C) in air. For the SiCf/[Si-B-C] composite, lifetime at 600°C is higher than 1000 h for a tension/compression cyclic loading of -50/+170 MPa. Nevertheless, the mechanical behaviour during the cyclic fatigue test is different at 600°C from that at 1200°C. Contrarily to 1200°C, at 600°C no specific evolution of the classical parameters used to characterize the mechanical behaviour during fatigue allows us to estimate the approach to fracture,. This indicates that the fatigue phenomena involved at 600°C are different from those involved at 1200°C. At 600°C, lifetime is mainly controlled by slow-crack-growth in the fibres in presence of air, and at 1200°C lifetime is controlled by fibre creep and oxidation.
G. Fantozzi et al., "Fatigue Behaviour of Structural Ceramic Composites", Advances in Science and Technology, Vol. 45, pp. 1664-1673, 2006