Abstract This study investigates the effect of Zr and C co-addition on the spark plasma sintered ZrB2-5 vol% Zr/graphite composites. Spark plasma sintering method was applied to consolidate and reinforce the composites by in-situ synthesis of ZrC through a chemical reaction between metallic Zr and graphite precursors. The effect of sintering temperature on the phase arrangement of the obtained composites was investigated by employing microstructural characterization techniques, mechanical properties measurements, and thermodynamic calculations. Results showed that the formation of ZrC cannot occur directly, while the in-situ reinforcement can be achieved indirectly if favorable thermodynamic and kinetic conditions provided. The sample sintered at 1700 °C showed a considerable amount of in-situ formed ZrC. However, in samples sintered at 1750 °C and 1800 °C, a diversity of phases was observed, mainly including ZrO2 polymorphs. It was also indicated that although higher sintering temperatures may improve hardness and densification of the composites, but may also cause poor fracture toughness. Consequently, the effect of sintering temperature on the phase arrangement and consequent characteristics of the prepared composites were fully addressed.

中文翻译：

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Zr和C共添加对ZrB2基陶瓷特性的影响：放电等离子烧结温度的作用

摘要 本研究研究了 Zr 和 C 共添加对放电等离子烧结 ZrB2-5 vol% Zr/石墨复合材料的影响。通过金属锆和石墨前驱体之间的化学反应，通过原位合成 ZrC，应用火花等离子体烧结方法来固结和增强复合材料。通过采用显微结构表征技术、机械性能测量和热力学计算，研究了烧结温度对所得复合材料相排列的影响。结果表明，ZrC 的形成不能直接发生，而如果提供有利的热力学和动力学条件，则可以间接实现原位增强。在 1700 °C 下烧结的样品显示出大量原位形成的 ZrC。然而，在 1750 °C 和 1800 °C 下烧结的样品中，观察到多种相，主要包括 ZrO2 多晶型物。也有人指出，虽然较高的烧结温度可以提高复合材料的硬度和致密性，但也可能导致断裂韧性较差。因此，充分解决了烧结温度对制备的复合材料的相排列和随之而来的特性的影响。