Analysis of the fracture behavior and mechanism of PIP-C/SiC composites at high temperatures

The high-temperature fracture toughness of C/SiC composites is of great significance for the tolerance assessment and safety application of components in service. In this work, combining the high-temperature experimental technique and phase field method, the fracture toughness of PIP-C/SiC composites at 25-1600 degrees C in inert atmosphere was tested, and the microcrack propagation at different temperatures was simulated. The fracture model considers the effects of residual stress, temperature-dependent properties of constituents and interfacial graphitization on the crack propagation process. The results show that the fracture toughness and modes of C/SiC composites have significant temperature dependence and difference in in-plane and out-of-plane orientations. As the increase of temperature, the cracks exhibit three typical modes of deflection, penetration and long-debonding at the fiber-matrix interphase. It is worth noting that C/SiC composites show a unique fracture mode at 1600 degrees C with the work of fracture increasing significantly. Overall, the work provides a guidance for the damage tolerance assessment of C/SiC composites in engineering.