Hot corrosion of the N5 nanocrystalline coating with 0.5 wt% Y addition with and without preoxidation under 75 wt% Na2SO4 + 25 wt% NaCl molten salts at 900 °C was investigated, in comparison with that of the NiCrAlY coating under the same condition. The results showed that the nanocrystalline coating with nano-columnar structure suffered more severe corrosion than NiCrAlY coating. The high density of grain boundaries in the nanocrystalline coating facilitated inward penetration of the corrosive medium and accelerated the destruction of the scale. Preoxidation significantly enhanced the corrosion resistance of the nanocrystalline coating by forming an exclusive Al2O3 scale on the surface that could prevent molten salt from accessing the coating surface. The coating preoxidized at 1000 °C exhibited the highest corrosion resistance with the least internal corrosion. Y stabilized Ta and/or S during preoxidation and subsequent corrosion process, improving the purity and stability of the scale. The coating preoxidized at 1100 °C performed worse than that at 1000 °C. The inferior corrosion resistance was attributed to the more Ta oxides segregation and faster consumption of Al at the higher preoxidation temperature, accelerating scale destruction during hot corrosion.

中文翻译：

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镍基单晶高温合金上含和不带预氧化和电弧离子镀层的溅射纳米晶涂层的热腐蚀


研究了在 900 °C 下在 75 wt% Na2SO4 + 25 wt% NaCl 熔盐下添加 0.5 wt% Y 的 N5 纳米晶涂层的热腐蚀，有和没有预氧化，与相同条件下的 NiCrAlY 涂层进行了比较。结果表明，具有纳米柱状结构的纳米晶涂层比 NiCrAlY 涂层遭受更严重的腐蚀。纳米晶涂层中高密度晶界促进了腐蚀介质的向内渗透并加速了氧化皮的破坏。预氧化通过在表面形成独特的 Al2O3 氧化皮，可以防止熔盐进入涂层表面，从而显着增强了纳米晶涂层的耐腐蚀性。在 1000 °C 下预氧化的涂层表现出最高的耐腐蚀性和最小的内部腐蚀。Y 在预氧化和随后的腐蚀过程中稳定了 Ta 和/或 S，提高了氧化皮的纯度和稳定性。在 1100 °C 下预氧化的涂层性能比在 1000 °C 下表现更差。 较差的耐腐蚀性归因于较高的预氧化温度下 Ta 氧化物的偏析更多和 Al 消耗更快，加速了热腐蚀过程中的水垢破坏。