Effect of fiber-oriented direction on mechanical and ablative performance of C/C-HfC-ZrC-SiC composites

C/C-HfC-ZrC-SiC composites are fabricated by precursor infiltration and pyrolysis process by using SiC, ZrC, and HfC precursors. With incorporation of ZrC-SiC ceramics, the ablation rates of the C/C-HfC-ZrC-SiC composites are one order magnitude lower than that of C/C-HfC composites. Due to structural difference of the preform and the distributed UHTC particles in two directions, C/C-HfC-ZrC-SiC composites show superior mechanical and ablative properties in XY direction. Meanwhile, the linear and mass ablation rates of XY direction are lower than that of XZ direction. The inferior ablation resistance of XZ direction is mainly concerned with the preferentially ablated fiber ends in cross-section and the absence of needled fibers in the fiber layers. After 240 s ablation test, the linear and mass ablation rates of XY and XZ directions are 0.167 ± 0.02 μm/s, 0.007 ± 0.002 mg/s and 0.521 ± 0.04 μm/s, 0.050 ± 0.003 mg/s, respectively. The lowest ablation rates after 240 s ablation indicate that the C/C-HfC-ZrC-SiC composites have great potential for long-term ablation applications.