Mechanical and ablation properties of a C/C-HfB2-SiC composite prepared by high-solid-loading slurry impregnation combined with precursor infiltration and pyrolysis

An improved high-solid-loading slurry impregnation process was developed to introduce HfB2 particles into a low-density C/C preform efficiently, and precursor infiltration and pyrolysis process was used for densification to obtain a C/C-HfB2-SiC composite. The microstructure characterization revealed that HfB2 particles uniformly filled the pores in the C/C preform, and SiC well densified the interstices between HfB2 particles and the small pores in the carbon fiber bundles. After being tested, the C/C-HfB2-SiC composite had a density of 4.07 g/cm3 and a bending strength of 344.8 MPa, and exhibited a non-brittle fracture behavior. After ablation with oxyacetylene flame at 2500 ℃ for 120 s, the mass ablation rate and linear ablation rate of the C/C-HfB2-SiC composite were 0.5 mg/s and 0.415 μm/s, respectively. The good ablation performance is attributed to the hindering effect of the HfO2 scale on oxygen diffusion at high temperature.