Effect of slurry and sol-gel introduce SiCnws on ablation and bending behaviors of modified SiCf/HfC-SiC composites

The slurry and sol-gel methods were used to introduce SiC nanowires (SiC nws ) into the SiC f /HfC-SiC composites. The microstructures, ablation, and bending behaviors of the SiC nws modified composites prepared by the two methods were compared. The bending strengths of the modified composites obtained by introducing SiC nws by the slurry and sol-gel methods were 224 ± 19 and 154 ± 14 MPa, respectively. The results showed that SiC fibers with chemical corrosion and thermal damage during the sol-gel process decreased the bending strength of the SiC nws -modified SiC f /HfC-SiC composites. Meanwhile, the pyrolytic carbon interface accompanying corrosion damage in the sol-gel process led to the degradation of interface function, which hindered the interface debonding and fiber sliding of the composites during the bending test. After ablation, the bending strengths of the two composites were 188 ± 19 and 50 ± 7 MPa, respectively. The bending strength retention of the modified composites fabricated by the slurry method (83.9%) was higher than that (32.5%) of the composites fabricated by the sol-gel method after ablation. As the composites fabricated by the slurry method exhibited a good ablation resistance under the oxyacetylene flame (∼2350°C).