Ablation property and oxide scale evolution of Y2O3 modified C/C-SiC composites fabricating via precursor infiltration and pyrolysis method

Employed precursors of Y(NO3)(3)center dot 6H(2)O and polycarbosilane, Y2O3 doped C/C-SiC composites were prepared by utilizing precursor infiltration and pyrolysis method. Results show that Y2O3 alters the composition of C/C-SiC composites with the generation of beta-Y2Si2O7 and Y2O3 together with slight Y2SiO5, Y-4.46(SiO4)(3)O and Y2C3. During ablation, beta-Y2Si2O7 is stable and directly liquefied to rapidly fill in the empties in the substrate; the other three are transformed to d-Y2Si2O7, evolving the oxide scale from SiO2-beta-Y2Si2O7-Y2O3 (semi-fused) layer to SiO2-beta-Y2Si2O7-delta-Y2Si2O7 ones. The ablation rates after ablation for 120 s were respectively 0.210 mg/s and 14.58 mu m/ s, severally decreased by 57.32% and 8.59% compared with that for 60 s. Further evaporation of SiO2 is suppressed and reconcilement of oxide layer is hence confirmed, implying decent anti-ablation resistance of oxide layer.