Cyclic fatigue behaviour at room temperature and at high temperature under inert atmosphere of a C/SiC multilayer composite

• Published in: Key engineering materials 1999-01, p.325-328
• Main Authors: Dalmaz, A, Reynaud, P, Rouby, D, Fantozzi, G, Abbe, F, Bourgeon, M
• Format: Article
• Language: English
• ISSN: 1013-9826

Cyclic fatigue at room temperature and at high temperature was investigated on a 2.5D C/SiC multilayer CMC, at the same maximum stress level but at various temperatures from room temperature to 1500 C under inert atmosphere. During cyclic fatigue the mechanical behavior, exhibited by stress/strain loops, evolves with the number of cycles applied. This evolution can be quantified by three parameters: the mean elastic modulus, the mechanical hysteresis, and the residual strain. The microstructural damages associated were also observed. The matrix exhibits a multiple crack at various scales: in the tows and between the tows, and the tows are totally debonded from their surrounding matrix shell. As shown by observations of microstructures and by the evolution of the mechanical hysteresis during cyclic fatigue tests, the origin of the cyclic fatigue in this composite can be attributed to progressive wear of the tow /surrounding matrix interfaces instead of the fiber/matrix interfaces. At high temperatures lower than 1000 C, this composite also exhibits an original increase of the mean elastic modulus, associated with a wide increase of the residual strain. (Author)