Excellent ablation resistance and reusability of silicon carbide fiber reinforced silicon carbide composite in dissociated air plasmas

This work explores the potentials of SiC fiber reinforced SiC matrix composites (SiCf/SiC) with SiC coating to resist aerodynamic ablations for thermal protection purpose. A plasma wind tunnel is employed to evaluate their anti-ablation property in dissociated air plasmas. The results suggest a critical ablation temperature of SiC coated SiCf/SiC, ≈ 1910 °C, which is the highest ever reported in literatures. Benefited by ‘all-SiC’ microstructures and relative flat ablated surfaces, the SiCf/SiC is still ablation-resistant up to ≈ 1820 °C after the occurrence of ablation. This implies an excellent ablation resistance and reusability property of SiCf/SiC, which surpasses that of traditional carbon fiber reinforced composites. Finally, an ablation mechanism dominated by surface characteristic is proposed. For the SiC coated SiCf/SiC, ablation is prone to take place at surface cracks formed by thermal mismatch; while for the ablated SiCf/SiC, ablation is triggered at the exposed fiber bundles which is over-heated in the plasmas.