This study aims at observing and understanding the oxidation mechanisms of ZrB₂-20 vol%SiC (ZS), HfB₂-20 vol%SiC (HS) and HfB₂-20 vol%SiC- 3 vol%Y₂O₃ (HSY) materials up to 2400 °C under water vapour conditions. After SPS sintering, fully densified samples were oxidized at several temperatures with 30 vol% H₂O/70 vol% Ar during 20 s. Weight variations as well as post-test microstructural and XRD analyses allowed understanding the influence of the composition on the oxidation behavior and the evolution of each oxide sublayer. Below 1550 °C, oxidation is limited, and thin oxide layers are observed. At 1900 and 2200 °C, ZS and HS show mechanical damage (cracks, spallation), while HSY keeps its structural integrity and interlayer adherence. The addition of Y₂O₃ reduces the damages due to thermal stresses in the material due to the stabilization of the cubic phase of HfO₂, and the formation of a Y₂Si₂O₇ interphase that mitigates thermal expansion mismatch between the SiC-depleted layer and the HfO₂ layer.

本研究旨在观察和了解ZrB ₂ -20 vol％SiC（ZS），HfB ₂ -20 vol％SiC（HS）和HfB ₂ -20 vol％SiC-3 vol％Y ₂ O ₃（HSY ）在水蒸气条件下温度高达2400°C的材料。SPS烧结后，完全致密化的样品在几个温度下被30vol％H ₂氧化。在20秒钟内O / 70 vol％Ar。重量变化以及测试后的微观结构和XRD分析使您能够了解组成对每个氧化亚层的氧化行为和演变的影响。低于1550°C，氧化受到限制，并且观察到薄的氧化层。在1900和2200°C下，ZS和HS表现出机械损伤（破裂，剥落），而HSY保持其结构完整性和层间附着力。Y ₂ O _3的添加减少了由于HfO ₂的立方相的稳定和材料Y ₂ Si ₂ O ₇的形成而引起的材料中的热应力造成的损害。减少SiC耗尽层和HfO ₂层之间的热膨胀失配的中间相。