Tension–tension fatigue damage characteristics of a 3D SiC/SiC composite in H2O–O2–Ar environment at 1300 °C

Tension–tension fatigue behaviors of a 3D woven SiC fiber (Hi-Nicalon) reinforced CVI SiC–matrix composite were measured in a H2O–O2–Ar environment at 1300 °C. The results indicated that the SiC/SiC had excellent fatigue resistance in H2O–O2–Ar atmosphere. Fiber/matrix interface debonding, sliding and fibers pull out in tension–tension fatigue tests were more obvious than those in monotonic tension tests. The cross-section surface of the monotonic tension specimens was coarse in whole, while that of the fatigue specimens were composed of ringed striations and smooth area. During tension–tension fatigue test, the coexisting damage characteristics were: (i) cracking of SiC matrix, disengaging of SiC matrix and grains growth; (ii) partial oxidation or burn out of pyrolytic carbon (PyC) interlayer and severe oxidation of fibers; (iii) fibers torn and fracture.