Ablation of C/Si C–Hf C composite prepared by precursor infiltration and pyrolysis in plasma wind tunnel

Carbon fiber reinforced silicon carbide-hafnium carbide（C/SiC-HfC） composite was prepared by precursor infiltration and pyrolysis process.Then,ablation behavior of C/SiC-HfC was evaluated in plasma wind tunnel.It was found that oxide layer formed during ablation significantly influenced the surface temperature.Formation of dense HfO2-SiO2 layer under low heat flux led to stable surface temperature.Silica（SiO2） on the surface was gradually consumed when heat flux increased,resulting in conversion of HfO2-SiO2 on the surface to HfO2.Converted HfO2 with high catalytic coefficient absorbed more energy,causing gradual increase in the surface temperature.Formed oxide layer was destroyed at high heat flux and high stagnation point pressure.After carbon fiber lost the protection of HfO2-SiO2 layer,it burned immediately,leading to surface temperature jump.