Thermal shock resistance and failure mechanisms of SiCf/SiC joints reinforced by nano-network structure

SiC f /SiC ceramic matrix composites are widely used in extreme thermal environments, where the joint region governs the structural reliability. In this work, the thermal shock resistance and failure mechanisms of SiC f /SiC joints reinforced by nano-network structure are investigated. Simulation results reveal that capillary forces drive molten Si to preferentially infiltrate small pores, while gas entrapment in larger pores leads to delayed infiltration and residual defects. Under thermal shock cycles at 1000 °C and 1200 °C, the joints exhibit progressive interfacial degradation and structural weakening. Microstructural observations confirm that thermal fatigue damage initiates at the interface between the SiC f /SiC substrate and the joint layer and propagates inward. After 30 cycles of thermal shock at 1000 °C and 1200 °C, the shear strength retention decreases to 10.83 % and 3.88 %, respectively. This study clarifies the damage mechanisms of SiC f /SiC joints under thermal shock and offers insights for designing high-reliability joints for extreme environments.