Tri-layer environmental barrier coatings (EBCs) were developed to provide complete encapsulation for carbon/carbon (C/C) composites, consisting of SiC inner layer, Si bond layer, and mixed YbSiO-YbSiO topcoats with varying mass ratios. The protective properties of the EBCs were assessed by exposing the coated samples to a corrosive gas mixture of 50 % O and 50 % HO at 1500 °C, the mass change, phase composition, and microstructure evolution were investigated. The results showed that a small amount of YbSiO doping could improve water vapor corrosion resistance, but the excessive content of YbSiO led to a mismatch of the coefficient of thermal expansion (CTE) with inner coating, resulting in coating cracking. The mixed topcoat with 60 wt% YbSiO and 40 wt% YbSiO showed superior water vapor corrosion resistance. After corrosion for 20 h at 1500 °C, no penetrating cracks of large size appeared, the thickness of thermal growth oxide (TGO, 4.6 ± 0.4 μm) was relatively lower, and the C/C substrate was effectively protected from damage.

中文翻译：

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C/C复合材料SiC/Si/混合Yb2Si2O7-Yb2SiO5环境屏障涂层的水蒸气腐蚀行为


开发了三层环境屏障涂层 (EBC)，为碳/碳 (C/C) 复合材料提供完整的封装，由 SiC 内层、Si 键合层和不同质量比的混合 YbSiO-YbSiO 面漆组成。通过将涂层样品暴露于 1500°C 的 50% O 和 50% H2O 的腐蚀性气体混合物中，评估 EBC 的保护性能，研究质量变化、相组成和微观结构演变。结果表明，少量YbSiO掺杂可提高耐水蒸气腐蚀性能，但YbSiO含量过高会导致内涂层热膨胀系数(CTE)不匹配，导致涂层开裂。含有 60wt% YbSiO 和 40wt% YbSiO 的混合面漆表现出优异的耐水蒸气腐蚀性。 1500℃腐蚀20h后，未出现大尺寸贯穿裂纹，热生长氧化物厚度（TGO，4.6±0.4μm）相对较低，有效保护了C/C基体免受损伤。