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

Abstract

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.