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Oxidation mechanisms under water vapour conditions of ZrB2-SiC and HfB2-SiC based materials up to 2400 °C
Journal of the European Ceramic Society ( IF 5.8 ) Pub Date : 2017-09-12 , DOI: 10.1016/j.jeurceramsoc.2017.09.015
V. Guérineau , A. Julian-Jankowiak

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.



中文翻译:

ZrB 2 -SiC和HfB 2 -SiC基材料在高达2400°C的水蒸气条件下的氧化机理

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。

更新日期:2017-09-12
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