Ablation behavior and mechanisms of 3D-Cf/Ta0.8Hf0.2C-SiC composite at temperatures up to 2500 °C

Abstract

In this work, ablation behavior and mechanisms of 3D-Cf/Ta0.8Hf0.2C-SiC composite were studied via air plasma test at temperatures up to 2500 °C. At temperatures below 2000 °C, a continuous oxides layer composed of o-Ta2O5(H) – t-Ta2O5 – Hf6Ta2O17(H) – SiO2 is formed on the ablation surface, which turns to o-Ta2O5(H) – SiO2 above 2200 °C. During ablation, o-Ta2O5(H) precipitates from the glassy SiO2 and grows up following Oswald ripening. Although the volatilization of SiO2 aggravates with ablation temperature increase and ablation time extension, o-Ta2O5(H) – SiO2 melt can still serve as effective self-healing similar to SiO2 glass. Accordingly, the multiphase oxides layer formed on the ablation surface provides a stable protective effect for the internal composite under all the tested ablation conditions. As a consequence, the 3D-Cf/Ta0.8Hf0.2C-SiC composite presents outstanding ablation-resistant performance even at 2500 °C for 300 s, with a linear recession rate of ∼ 5.7 µm/s and a mass recession rate of 2.91 mg/s.