Oxidation and strength retention of HfB₂−SiC composite with La₂O₃ additives

ABSTRACT

The oxidation and its effect on room temperature flexural strength were examined in hot-pressed 3 vol.-% La₂O₃-doped HfB₂-20 vol.-% SiC composite exposed to air at 1400°C and 1500°C, respectively, for up to 100 h. The major oxidation products consisted of SiO₂ (α-cristobalite), La₂Si₂O₇, HfO₂ and HfSiO₄ regardless of oxidation temperature. However, the morphology of the microstructure of the oxidised surfaces was shown to be dependent on oxidation temperature. In addition, it was found that the room temperature flexural strength of the composite degraded after oxidation and the degradation of strength depended on oxidation time at temperature and oxidation temperature. The strength retention displayed by composite after 100 h of oxidation at 1400°C and 1500°C was ∼83% and ∼74%, respectively.

KEYWORDS:

• Hafnium diboride
• Silicon carbide
• composite
• oxidation
• flexural strength

Disclosure statement

No potential conflict of interest was reported by the author(s).