Comparisons of cyclic fatigue hysteresis between C/SiC and SiC/SiC ceramic-matrix composites with different fiber preforms at room and elevated temperatures

In this paper, the cyclic fatigue hysteresis of carbon fiber reinforced silicon carbide (C/SiC) and SiC/SiC ceramic-matrix composites with different fiber preforms at room and elevated temperatures is investigated. The evolution of fatigue hysteresis dissipated energy versus applied cycle number for unidirectional C/SiC (sigma(max) = 240 MPa at room temperature and sigma(max) = 250 MPa at 800celcius in air atmosphere), cross-ply C/SiC (sigma(max) = 105 MPa at room temperature and 800celcius in air atmosphere), 2D C/SiC (sigma(max) = 387 and 425 MPa at room temperature), 2.5D C/SiC (sigma(max) = 180 MPa at room temperature, sigma(max) = 140 MPa at 800celcius in air atmosphere, and sigma(max) = 230 MPa at 600celcius in inert atmosphere), 2D SiC/SiC (sigma(max) = 130 MPa at 600celcius, 800celcius, and 1000celcius in inert atmosphere, sigma(max) = 80 MPa at 1000celcius in air atmosphere, sigma(max) = 100 MPa at 1000celcius in steam atmosphere, sigma(max) = 140 MPa at 1200celcius in air and in steam atmospheres, sigma(max) = 90, 120 MPa at 1300celcius in air atmosphere), and 3D SiC/SiC (sigma(max) = 100 MPa at 1300celcius in air atmosphere) is analyzed. The change rate of the fatigue hysteresis dissipated energy between C/SiC and SiC/SiC composites is compared. The fatigue hysteresis dissipated energy decreases with applied cycle number for unidirectional, and cross-ply C/SiC composite at 800celcius in air, and 2.5D C/SiC composite at 600celcius in inert; and the fatigue hysteresis dissipated energy increases with applied cycle number for 2.5D C/SiC composite at 800celcius in air, 2D SiC/SiC composite at 600celcius, and 800celcius in inert.