Oxidation behavior of boron-containing (Zr,Ti)C <sub> <i>x</i> </sub>B <sub> <i>y</i> </sub> solid solution ceramics at 1600 °C in air
Huilin Lun, Yi Zeng, Xiang Xiong, Houbu Li
Abstract
Multicomponent boron-containing carbide coating (i.e., (Zr,Ti)C<em><sub>x</sub></em>B<em><sub>y</sub></em>) on a C/C composite shows good ablation resistance. However, the high temperature oxidation behavior of this new type of boron-containing (Zr,Ti)C<em><sub>x</sub></em>B<em><sub>y</sub></em> solid solution ceramic has not been clarified yet. The present work fabricated (Zr,Ti)C<em><sub>x</sub></em>B<em><sub>y</sub></em> solid solution block ceramic by spark plasma sintering and its oxidation behavior at 1600°C in air (N<sub>2</sub>–20-vol.% O<sub>2</sub>) was investigated for the first time. The effects of boron on the oxidation resistance of (Zr,Ti)C<em><sub>x</sub></em>B<em><sub>y</sub></em> ceramic were examined. The results indicate that (Zr,Ti)C<em><sub>x</sub></em>B<em><sub>y</sub></em> ceramic displays a good oxidation resistance with a parabolic rate law described oxidation process. After trace solution of boron (0.5 wt%) into (Zr,Ti)C<em><sub>x</sub></em>, the oxidation resistance of carbide ceramic is significantly enhanced, leading to a decrease of 30% of oxidation rate constant. The formed oxide scale in (Zr,Ti)C<em><sub>x</sub></em>B<em><sub>y</sub></em> ceramic is dense and the interlayer shows a stronger ability of inhibiting the inward diffusion of oxygen. In addition, the introduction of boron leads to a more negative binding energy of (Zr,Ti)C<em><sub>x</sub></em>B<em><sub>y</sub></em> and improves the oxidation resistance of carbide.