Effect of Si2BC3N additions on the oxidation of Ta4HfC5 ceramics at 900–1100 °C

Si ₂BC ₃ N content held the key on the oxidation scale growth and damage mechanism of Ta ₄HfC ₅ ceramics oxidized at 900–1100 °C. Si ₂BC ₃N addition increased the oxidation scale thickness due to the micro-pores generated by BN(C) oxidation constructing oxygen-diffusion channel. However, Ta ₄HfC ₅-10 wt% Si ₂BC ₃ N showed better oxidation resistance in the Ta ₄HfC ₅-5–20 wt% Si ₂BC ₃ N ceramics, resulting from the dynamic equilibrium of pores healing and tantalum-hafnium silicate glass generation. Generally, Ta ₄HfC ₅ tended to oxidize firstly followed by the oxidation of Si ₂BC ₃N, whereas oxidizing products of Si ₂BC ₃N like substantial B ₂O ₃ and few SiO ₂ were insufficient to the formation of dense oxide scale at 900–1100 °C.