Cyclic fatigue behaviour at high temperature of self-healing ceramic matrix composite
Résumé
This work aimed at studying the mechanical behaviour of a 2.5D SiC/SiBC composite with a self-healing matrix by cyclic fatigue at high temperature in air. The experiments were performed at 600°C and at 1200°C in air, in order to measure the lifetime of this composite, and to point out the good protective role of the self-healing matrix against oxidation at 600°C and 1200°C. At 600°C, lifetime exceeds 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 one 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 controlled by slow crack growth in the fibres, and at 1200°C lifetime is controlled by fibre creep