Tension-tension fatigue behavior of a PIP SiC/SiC composite at elevated temperature in air

The tension–tension fatigue behavior of a PIP Silicon Carbide/Silicon Carbide (SiC/SiC) composite was investigated at 1300 °C in air. The composite consisted of a new precursor polymer (LPVCS) pyrolyzed SiC matrix reinforced with pyrolytic carbon (PyC) coated 3D braided KD-I SiC fibers. Environmental barrier coatings (EBC) were employed to enhance the durability and air oxidation resistance of the composite at high temperature. Tension–tension fatigue tests were conducted at 1300 °C in laboratory air at frequency of 1 Hz. The ratio of minimum stress to maximum stress was 0.1, with maximum stresses ranging from 40 to 120 MPa. Fatigue run-out was defined as 105 cycles. Strain accumulation with cycles and modulus evolution with cycles were analyzed for each fatigue test. Fatigue limit of SiC/SiC composite with EBC was 60 MPa which was slightly higher than that without EBC. The microstructure as well as damage and failure mechanisms of the composites were investigated.