Ablative and mechanical properties of C/C-SiC-ZrC composites modified with PyC/SiC and PyC/BN interface layers

Two kinds of novel modified C/C-SiC-ZrC composites were prepared via precursor infiltration and pyrolysis, as pyrocarbon (PyC)/silicon carbide (SiC) and PyC/boron nitride (BN) dual-layer interphases were separately structured on the fibers by means of chemical vapor infiltration. Data analysis and conclusions are served for investigating the effects of these two interface layers on mechanical and anti-ablative properties. On the mechanical property hand, both PyC/BN and PyC/SiC interphase layers play positive roles, resting with the reduction of fiber damage during the fabrication process. Compared with BN, SiC shows better enhancement as the flexural strength of PyC/BN and PyC/SiC interphase-modified composites are 214.9 and 229.2 MPa, respectively. On the ablative property hand, after oxyacetylene flame ablation for 60 s, the mass and linear ablation rates of the composites modified by PyC/SiC interface were 2.2 mg/s and 9.7 mu m/s, which is much lower than that modified by PyC/BN. The inferior ablation properties of PyC/BN-CSZ were attributed to the vaporization of the B2O3 gas that destroys the integrity of the oxide film and oxygen erosion on the substrate through the damaged BN interface.

Automated summary

Two types of novel modified C/C-SiC-ZrC composites were prepared with PyC/SiC and PyC/BN dual-layer interphases formed on fibers through chemical vapor infiltration. The PyC/SiC interface showed better enhancement in mechanical properties and lower ablation rates compared to the PyC/BN interface modified composites.