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

Abstract

Si2BC3N content held the key on the oxidation scale growth and damage mechanism of Ta4HfC5 ceramics oxidized at 900–1100 °C. Si2BC3N addition increased the oxidation scale thickness due to the micro-pores generated by BN(C) oxidation constructing oxygen-diffusion channel. However, Ta4HfC5-10 wt% Si2BC3N showed better oxidation resistance in the Ta4HfC5-5–20 wt% Si2BC3N ceramics, resulting from the dynamic equilibrium of pores healing and tantalum-hafnium silicate glass generation. Generally, Ta4HfC5 tended to oxidize firstly followed by the oxidation of Si2BC3N, whereas oxidizing products of Si2BC3N like substantial B2O3 and few SiO2 were insufficient to the formation of dense oxide scale at 900–1100 °C.