Tensile Creep Behavior of Cansas-II SiCf/SiC Composites at High Temperatures

Continuous silicon carbide fiber reinforced silicon carbide composite (SiCf/SiC) is a key material for the advanced aero-engines. It is required to possess excellent high-temperature creep resistance for SiCf/SiC to meet the long-term service lifetime of the aero-engines. Here, tensile creep behaviors of a plain woven Cansas-II SiCf/SiC (2D-SiCf/SiC) were investiged in the temperature of 1200-1400 degrees C with the stress levels of 80 to 140 MPa. Its microstructure and fracture morphology were observed, and composition was analyzed. Results show that creep-rupture time of 2D-SiCf/SiC is more than 500 h and steady-state creep rate is 1x10(-10)-5x10(-10) /s at stresses lower than the proportional limit stress (sPLS). The creep behaviors are controlled by matrix and fibers. The creep-rupture time is significantly reduced, and the steady-state creep rate is increased by an order of magnitude when the stress is higher than the sPLS. The matrix, fibers and interfaces of the composite are greatly oxidized, and the creep behaviors are mainly controlled by the fibers.