Effects of LaB6 on composition, microstructure and ablation property of the HfC-TaC-SiC doped C/C composites prepared by precursor infiltration and pyrolysis

Abstract HfC, TaC and SiC with different proportions were introduced into Cf/LaB6 preform to fabricate four kinds of UHTC doped C/C composites. Results show that LaB6 could react with HfC or TaC to establish a compact ceramic structure. After ablation for 120 s, the composites doped with LaB6-HfC-TaC-SiC possessed the best ablation property, and the ablation rates were 1.129 mg/s and 3.133 μm/s. A layer with La2Si2O7, La2Hf2O7 and LaTaO4 is observed due to the reactions between La2O3 and other binary oxides. Further ablation was suppressed and stability of the multi-phase layer is therefore confirmed, indicating good coordination among the oxides.