Effect of slurry and sol‐gel introduce SiC_nws on ablation and bending behaviors of modified SiC_f/HfC‐SiC composites

Abstract

The slurry and sol‐gel methods were used to introduce SiC nanowires (SiCnws) into the SiCf/HfC‐SiC composites. The microstructures, ablation, and bending behaviors of the SiCnws modified composites prepared by the two methods were compared. The bending strengths of the modified composites obtained by introducing SiCnws 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 SiCnws‐modified SiCf/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).

Fabrication and properties of SiCnw‐reinforced SiC composites by reactive melt infiltration with BN and PyC interface

“…To date, one of the most common methods to improve the mechanical properties of SiC ceramics matrix composites (SiC CMCs) is introduced various reinforcements, for example, SiC whiskers (SiC w ), 4 carbon fibers (C f ), 5,6 carbon nanotubes (CNTs), 7 SiC ceramic fibers (SiC f ), 8–10 and SiC nanofibers (SiC nf ), 11 or SiC nanowires (SiC nw ), 12,13 which are considered an effective way to improve the mechanical properties of SiC CMC by consuming more energy. Among them, single‐crystal SiC nanowires (SiC nw ) have more promising application, owing to their high Young's modulus (660 GPa), high flexural strength (maximum flexural strength of 53.4 GPa), excellent thermal, and electrical properties 14–16 .…”