Abstract Commercial mullite powders show great potential for application in environmental barrier coatings. However, most of the commercial mullite powders contain amorphous silica, which produces volatile silicon hydroxide in hot steam. This leads to serious recession of mullite coatings in hot water vapor. In this study, a Y2O3-doped mullite-ZrSiO4 coating was fabricated on C/C–SiC composites using the slurry painting method. The addition of Y2O3 resulted in the elimination of the residual silica and derived-cristobalite in the commercial mullite powder, leading to the formation of a stable mullite-Y2Si2O7–ZrSiO4 coating. This indicates that Y2O3 can efficiently enhance the phase stability of commercial mullite at high temperatures. In addition, the corrosion behaviours of Y2O3-doped mullite-ZrSiO4 coatings were investigated at 1373, 1573, and 1773 K in a 95% H2O-5% O2 atmosphere. The coatings exhibited good corrosion resistance. The 15 mol% Y2O3 coating showed a weight loss rate of 1.62 wt % when exposed to hot steam for 10 h at 1573 K. This value is only 1/8th of that of the uncoated sample. Moreover, ZrSiO4 improved the water corrosion resistance of the Y2O3-doped mullite-ZrSiO4 coatings at 1573 K.

中文翻译：

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在 1373-1773 K 温度下，在湿气存在下，涂覆在 C/C-SiC 复合材料上的 Y2O3 掺杂莫来石-ZrSiO4 涂层的腐蚀行为

摘要 商业莫来石粉末在环境阻隔涂料中显示出巨大的应用潜力。然而，大多数商业莫来石粉末含有无定形二氧化硅，它在热蒸汽中产生挥发性氢氧化硅。这导致莫来石涂层在热水蒸汽中严重衰退。在这项研究中，使用浆料喷涂方法在 C/C-SiC 复合材料上制备了 Y2O3 掺杂的莫来石-ZrSiO4 涂层。Y2O3 的添加消除了商业莫来石粉末中残留的二氧化硅和衍生方石英，从而形成了稳定的莫来石-Y2Si2O7-ZrSiO4 涂层。这表明 Y2O3 可以有效提高商品莫来石在高温下的相稳定性。此外，研究了掺杂 Y2O3 的莫来石-ZrSiO4 涂层在 1373、1573、在 95% H2O-5% O2 气氛中为 1773 K。涂层表现出良好的耐腐蚀性。当暴露于 1573 K 的热蒸汽 10 小时时，15 mol% Y2O3 涂层的重量损失率为 1.62 wt%。该值仅为未涂层样品的 1/8。此外，ZrSiO4 提高了掺杂 Y2O3 的莫来石-ZrSiO4 涂层在 1573 K 下的耐水腐蚀性能。