High-temperature oxidation behavior of monolithic Zr-3[Al(Si)](4)C-6 and its composite incorporating 30vol% ZrB2-SiC: Providing a basis for broadening the service temperature

To provide a basis for the high-temperature oxidation of ultra-high temperature ceramics (UHTCs), the oxidation behavior of Zr-3[Al(Si)](4)C-6 and a novel Zr-3[Al(Si)](4)C-6-ZrB2-SiC composite at 1500 degrees C were investigated for the first time. From the calculation results, the oxidation kinetics of the two specimens follow the oxidation dynamic parabolic law. Zr-3[Al(Si)](4)C-6 exhibited a thinner oxide scale and lower oxidation rate than those of the composite under the same conditions. The oxide scale of Zr-3[Al(Si)](4)C-6 exhibited a two-layer structure, while that of the composite exhibited a three-layer structure. Owing to the volatilization of B2O3 and the active oxidation of SiC, a porous oxide layer formed in the oxide scale of the composite, resulting in the degradation of its oxidation performance. Furthermore, the cracks and defects in the oxide scale of the composite indicate that the reliability of the oxide scale was poor. The results support the service temperature of the obtained ceramics.