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The oxidation behavior of polymer‐derived (Hf x Ta 1− x )C/SiC nanocomposites at 1200 °C and 1400 °C for up to 100 h is investigated in this work. Overall, the chemical modification of the polycarbosilane‐based precursor with Hf and Ta leads to an improved oxidation behavior due to an increased densification. Shifting the Hf/Ta ratio from (Hf 0.2 Ta 0.8 )C/SiC to (Hf 0.7 Ta 0.3 )C/SiC results in an improved oxidation behavior due to Hf 6 Ta 2 O 17 formation and the reduction of Ta 2 O 5 formation, which reduces cracking of the samples. The formation and microstructure of SiO 2 as well as the internal oxidation of (Hf x Ta 1− x )C precipitates is explained by thermodynamic and kinetic considerations.
Petry et al. (2024) studied this question.