Abstract

The HfB₂–30 vol % SiC composite powders modified with a small (2 and 5 vol %) amount of Y₃Al₅O₁₂ were synthesized by the sol–gel method. Such a modification in producing an ultra-high-temperature ceramic of the corresponding composition optimized the process temperature and increased the oxidation resistance of the ceramic by stabilizing the formed hafnium dioxide in the cubic or tetragonal form. It was determined that the introduced X-ray amorphous phase Y₃Al₅O₁₂ was distributed as a thin film on particles of hafnium diboride and silicon carbide and led to agglomeration of the latter; no formation of individual Y₃Al₅O₁₂ particles was observed. Investigation of the thermal behavior of the obtained composite powders in an air flow in the temperature range 20–1200°C showed that the introduction of 5 vol % Y₃Al₅O₁₂ virtually completely neutralized the effect of the initial surface oxidation of HfB₂ in the temperature range 700–800°C, shifted the temperature of the beginning of oxidation and the maximum of the corresponding thermal event from 756 to 808°C, and decreased the intensity of this thermal event.

中文翻译：

---

Y 3 Al 5 O 12改性的HfB 2 –30 vol％SiC复合粉末的制备及抗氧化性能

摘要

通过溶胶-凝胶法合成了HfB ₂ –30 vol％的SiC复合粉末，并经少量（2和5 vol％）的Y ₃ Al ₅ O ₁₂改性。生产相应组成的超高温陶瓷的这种改进通过稳定形成的立方或四方形式的二氧化ha，优化了工艺温度并提高了陶瓷的抗氧化性。可以确定，引入的X射线非晶相Y ₃ Al ₅ O ₁₂以薄膜形式分布在二硼化and和碳化硅的颗粒上并导致它们的附聚。没有形成单独的Y ₃ Al ₅观察到O ₁₂颗粒。对所得复合粉末在20–1200°C温度范围内的气流中的热行为的研究表明，引入5 vol％的Y ₃ Al ₅ O ₁₂几乎完全中和了HfB ₂初始表面氧化的影响。在700–800°C的温度范围内，将氧化开始的温度和相应热事件的最大值从756移至808°C，并降低了此热事件的强度。