Carbon fiber reinforced silicon carbide (C/SiC) composites are usually subjected to thermal-mechanical-oxidation-coupled loads during service. However, their mechanical properties at ultra-high temperatures in oxidizing environments have rarely been reported. In this paper, a method based on the induction heating technology is proposed for testing the ultra-high-temperature mechanical properties of materials in air. The flexural behaviors of a 2D plain-weave C/SiC material prepared via chemical vapor infiltration are investigated in air up to 1800 °C for the first time. Inverse temperature dependences of the flexural modulus and strength are observed. New fracture mechanisms that are responsible for the mechanical behaviors at elevated temperatures are elucidated. Fracture modes at different temperatures are proposed. A high-temperature fracture strength model for oxidizing environments is developed, which is in good agreement with the experimental results. The factors affecting the fracture strength behaviors of the C/SiC in air at elevated temperatures are characterized quantitatively.

碳纤维增强碳化硅 (C/SiC) 复合材料在使用过程中通常会承受热-机械-氧化-耦合载荷。然而，它们在氧化环境中的超高温下的机械性能鲜有报道。本文提出了一种基于感应加热技术的材料在空气中的超高温力学性能测试方法。首次在高达 1800 °C 的空气中研究了通过化学蒸汽渗透制备的二维平纹 C/SiC 材料的弯曲行为。观察到弯曲模量和强度的逆温度依赖性。阐明了导致高温下机械行为的新断裂机制。提出了不同温度下的断裂模式。建立了氧化环境的高温断裂强度模型，与实验结果吻合较好。定量表征了影响 C/SiC 在空气中高温下断裂强度行为的因素。