Mini-SiC_f/SiC 复合材料长时间高温下的力学性能演变

Continuous silicon carbide fiber reinforced silicon carbide (SiC_f/SiC) composites are widely utilized in the hot-end components of aero engines due to their exceptional properties and high-temperature resistance. To ensure the safety and reliability of SiC_f/SiC composite parts during service, it is crucial to investigate the evolution of their mechanical properties under prolonged high-temperature exposure. In this study, mini-SiC_f/SiC composites with a BN interface were fabricated using Cansas-II SiC fibers. These mini-SiC_f/SiC composites underwent heat treatment at 1100, 1200, and 1350 ℃ for durations of 5, 10, 50, 100, and 200 h, respectively, to examine the effects of high-temperature and long-term heat treatment on their mechanical properties and microstructure. The results show that at 1100 ℃, heat treatment has no significant impact on the mini-SiC_f/SiC composites. The mechanical properties remain largely unchanged, and the contribution fractions of each stage to the overall mechanical performance remain consistent. At 1200 ℃, short-term heat treatment shows minimal effects on the mini-SiC_f/SiC composites without notable change in tensile strength. However, prolonged heat treatment leads to damage in the SiC fibers, thereby decreasing their tensile strength. At 1350 ℃, heat treatment significantly improves the properties of the BN interface but causes severe damage to the SiC fibers, resulting in a marked decline in the mechanical properties of the mini composites. As the heat treatment duration increases, the extent of fiber damage intensifies, leading to a continuous deterioration in the mechanical performance of the composites.