Preparation of SiC–ZrC composite powders by carbothermal reduction method and its high-temperature oxidation resistance performance

Ultra-high temperature ceramic materials possess irreplaceable value in extreme environments, among which SiC–ZrC multiphase ceramics have emerged as a research focus due to their exceptional high-temperature performance. The synthesis of high-quality composite powders is pivotal for the fabrication of high-performance ceramics. To address the limitations of conventional carbothermal reduction methods—including impurity contamination from organic carbon sources, inadequate reaction stability, and the paucity of research on the oxidation behavior and biphase synergistic mechanisms of SiC–ZrC composite powders—this study developed a novel controlled carbothermal reduction process using high-purity graphite as the carbon source (argon atmosphere, 1400–1600 °C). Systematic investigations were conducted to elucidate the regulatory effects of calcination temperature on the phase composition, microstructure, and elemental distribution of the powders. Additionally, high-temperature oxidation experiments under air atmosphere were performed to reveal the oxidation behavior characteristics and biphase synergistic mechanisms of the powders. The results demonstrate that high-purity SiC–ZrC composite powders with uniformly distributed elements can be successfully synthesized at 1600 °C with a 1.5-h holding time. During high-temperature oxidation, SiC exhibits significantly superior oxidation resistance compared to ZrC:ZrC initiates oxidation to form ZrO₂ as early as 800 °C, while SiC retains excellent structural stability even at 1500 °C. The two phases achieve synergistic oxidation enhancement through the formation of SiO₂–ZrO₂ composite oxide layers and ZrSiO₄ phases.