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<p>This study employed atmospheric plasma spraying to fabricate a Si/Yb<sub>2</sub>Si<sub>2</sub>O<sub>7</sub> environmental barrier coating on a SiC ceramic substrate. The oxidation behavior and microstructural evolution of the coating were systematically investigated at 1300&#xa0;°C under atmospheres containing different water vapor contents (25&#xa0;vol.% and 35&#xa0;vol.%). The results indicate that the as-sprayed coating primarily consists of the Yb<sub>2</sub>Si<sub>2</sub>O<sub>7</sub> phase, with minor amounts of Yb<sub>2</sub>Si<sub>2</sub>O<sub>5</sub>, SiO<sub>2</sub>, and amorphous phases. Porosity and microcracks were inherently present within the coating structure. During high-temperature water vapor-oxygen corrosion, the overall phase composition of the coating remained stable. However, oxidation of the Si bond coat led to the formation of a thermally grown oxide (TGO) layer. Water vapor content was found to significantly influence the corrosion behavior: although the parabolic oxidation rate constants under 25&#xa0;vol.% and 35&#xa0;vol.% conditions showed little difference, the TGO layer grew thicker and more rapidly at the higher water vapor content (35&#xa0;vol.%), with the long-term thickness increasing by approximately 1.34&#xa0;times after 300 hours. This is primarily attributed to enhanced sintering and volatilization of the Yb<sub>2</sub>Si<sub>2</sub>O<sub>7</sub> coating in high water vapor environments, which promotes the propagation of internal defects. These defects create additional pathways for oxygen and water vapor diffusion toward the Si bond coat, accelerating TGO growth. Overall, the Si/Yb<sub>2</sub>Si<sub>2</sub>O<sub>7</sub> coating demonstrates good phase stability at 1300&#xa0;°C across the tested water vapor conditions; however, elevated water vapor levels can substantially reduce long-term durability by accelerating TGO thickening.</p>

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Microstructure and Oxidation Kinetics of Si/Yb2Si2O7 Environmental Barrier Coatings under Different Water Vapor Contents at 1300 °C

  • 期刊论文

  • 发表日期：

    2026年1月27日

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  • JiaKuan Chen,
  • Xun Ni,
  • Zhenzhuang Zhao,
  • Chenghao Liu,
  • Taihong Huang,
  • Qing Li,
  • Dehao Kong,
  • Peng Song

摘要

This study employed atmospheric plasma spraying to fabricate a Si/Yb2Si2O7 environmental barrier coating on a SiC ceramic substrate. The oxidation behavior and microstructural evolution of the coating were systematically investigated at 1300 °C under atmospheres containing different water vapor contents (25 vol.% and 35 vol.%). The results indicate that the as-sprayed coating primarily consists of the Yb2Si2O7 phase, with minor amounts of Yb2Si2O5, SiO2, and amorphous phases. Porosity and microcracks were inherently present within the coating structure. During high-temperature water vapor-oxygen corrosion, the overall phase composition of the coating remained stable. However, oxidation of the Si bond coat led to the formation of a thermally grown oxide (TGO) layer. Water vapor content was found to significantly influence the corrosion behavior: although the parabolic oxidation rate constants under 25 vol.% and 35 vol.% conditions showed little difference, the TGO layer grew thicker and more rapidly at the higher water vapor content (35 vol.%), with the long-term thickness increasing by approximately 1.34 times after 300 hours. This is primarily attributed to enhanced sintering and volatilization of the Yb2Si2O7 coating in high water vapor environments, which promotes the propagation of internal defects. These defects create additional pathways for oxygen and water vapor diffusion toward the Si bond coat, accelerating TGO growth. Overall, the Si/Yb2Si2O7 coating demonstrates good phase stability at 1300 °C across the tested water vapor conditions; however, elevated water vapor levels can substantially reduce long-term durability by accelerating TGO thickening.