Flexural properties of cyclic ablated SiC_f/HfC-SiC composites

To improve the reliability of C_f/HfC-SiC composites after ablation, SiC fibers were used as reinforcement to replace carbon fibers. The composites were prepared by precursor infiltration and pyrolysis (PIP) and chemical vapor deposition (CVD) methods. The flexural properties of the cyclic ablated C_f/HfC-SiC and SiC_f/HfC-SiC composites were characterized. The results showed that the flexural strengths of C_f/HfC-SiC and SiC_f/HfC-SiC composites before ablation were 98.3 ± 6.8 and 108.5 ± 1.9 MPa, respectively. After three cycles of ablation, the flexural strengths of C_f/HfC-SiC composites were 37.2 ± 2.4 MPa (decreased by about 62.2%), and the bending strengths of SiC_f/HfC-SiC composites were 79.6 ± 4.3 MPa (only decreased by 26.6%). The high retention rate of the bending strength of SiC_f/HfC-SiC composites was due to the protection of the complete oxide layer and good oxidation resistance of the SiC fiber.