Abstract This research presents the influence of Al addition on microstructure and mechanical behavior of ZrB2–SiC ultra-high temperature ceramic matrix composite (UHTCMC) fabricated by spark plasma sintering (SPS). A 2.5 wt% Al-doped ZrB2–20 vol% SiC UHTCMC was produced by SPS method at 1900 °C under a pressure of 40 MPa for 7 min. The microstructural and phase analysis of the composite showed that aluminum-containing compounds were formed in-situ during the SPS as a result of chemical reactions between Al and surface oxide films of the raw materials (i.e. ZrO2 and SiO2 on the surfaces of ZrB2 and SiC particles, respectively). The Al dopant was completely consumed and converted to the intermetallic Al3Zr and Al4Si compounds as well as Al2O3 and Al2SiO5. A relative density of 99.8%, a hardness (HV5) of 21.5 GPa and a fracture toughness (indentation method) of 6.3 MPa m1/2 were estimated for the Al-doped ZrB2–SiC composite. Crack bridging, branching, and deflection were identified as the main toughening mechanisms.

中文翻译：

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Al掺杂ZrB2-SiC复合材料的放电等离子烧结

摘要 本研究介绍了添加铝对放电等离子烧结 (SPS) 制备的 ZrB2-SiC 超高温陶瓷基复合材料 (UHTCMC) 的微观结构和机械性能的影响。2.5 wt% Al 掺杂 ZrB2–20 vol% SiC UHTCMC 在 1900 °C 和 40 MPa 压力下通过 SPS 方法生产 7 分钟。复合材料的显微结构和物相分析表明，在 SPS 过程中，由于 Al 与原材料的表面氧化膜（即 ZrB2 和 SiC 表面的 ZrO2 和 SiO2）发生化学反应，在原位形成了含铝化合物。粒子）。Al 掺杂剂被完全消耗并转化为金属间化合物 Al3Zr 和 Al4Si 以及 Al2O3 和 Al2SiO5。相对密度99.8%，硬度（HV5）21。5 GPa 和 6.3 MPa m1/2 的断裂韧性（压痕法）被估计为 Al 掺杂的 ZrB2-SiC 复合材料。裂纹桥接、分支和偏转被确定为主要的增韧机制。