The mechanical properties and microstructure of C_f/ZrC-SiC composites prepared via slurry injection combined with precursor impregnation and pyrolysis at a low temperature of 1100 °C

To address the challenges in current fabrication methods for ultra-high temperature ceramic matrix composites, particularly the susceptibility of carbon fibers to microstructural damage and the difficulty in achieving wide-ranging control over composition and content, this study developed a novel 1100 °C low-temperature pressureless densification process. This process integrates high-frequency ultrasonic vibration-assisted slurry injection with precursor infiltration and pyrolysis. This method successfully prepares C_f/ZrC-SiC composites. The results indicate that this process can effectively introduce a high solid content ZrC matrix uniformly into the preform with minimal damage to the carbon fibers during the fabrication process. Under load, the fiber pull-out length is extended, and the mechanisms of crack deflection and branching work synergistically to enhance toughness. The maximum flexural strength reached 239.1 MPa, with a fracture toughness of 14.3 MPa•m1/2. Compared to C_f/C-ZrC-SiC composites fabricated via the conventional Reactive Melt Infiltration process, the flexural strength was improved by 18.6% and the fracture toughness was enhanced by 38.3%.