Oxidation behavior of boron-containing (Zr,Ti)C_xB_y solid solution ceramics at 1600 °C in air

Multicomponent boron-containing carbide coatings (i.e., (Zr,Ti)C_xB_y) on a C/C composite show good ablation resistance. However, the high-temperature oxidation behavior of this new type of boron-containing (Zr,Ti)C_xB_y solid solution ceramics has not been clarified yet. The present work fabricated (Zr,Ti)C_xB_y solid solution block ceramics by spark plasma sintering, and their oxidation behavior at 1600 ℃ in air (N₂–20-vol% O₂) was investigated for the first time. The effects of boron on the oxidation resistance of (Zr,Ti)C_xB_y ceramics were examined. The results indicate that the (Zr,Ti)C_xB_y ceramics display good oxidation resistance with the parabolic rate law describing the oxidation process. After the trace solution of boron (0.5 wt%) into (Zr,Ti)C_x, the oxidation resistance of carbide ceramics is significantly enhanced, leading to a decrease of 30% in the oxidation rate constant. The formed oxide scale in the (Zr,Ti)C_xB_y ceramics is dense, and the interlayer shows stronger ability to inhibit inward diffusion of oxygen. In addition, the introduction of boron leads to more negative binding energy of (Zr,Ti)C_xB_y and improves the oxidation resistance of carbides.