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<p>In this study, a gas turbine blade made of IN738LC with a MCrAlY coating (Co-32Ni-21Cr-8Al-0.5Y), which had been in service for 33,000&#xa0;h at high temperatures, was examined for corrosion and oxidation. The turbine operated at a turbine inlet temperature of 1075&#xa0;°C, using natural gas fuel primarily composed of methane and butane. The analysis focused on three regions: the leading edge airfoil surface and internal cooling passages in the top, middle, and near-platform sections—corresponding to temperature zones of approximately 800, 900, and 700&#xa0;°C, respectively. Investigations were conducted using field emission scanning electron microscopy (FE-SEM) and energy-dispersive x-ray spectroscopy (EDS). The results showed that the morphology and cross-sectional features of coating degradation and internal oxidation in the cooling regions aligned with findings from other studies conducted under similar temperature conditions. No corrosion products related to sulfur or alkaline salts were identified; instead, only typical oxides originating from the base metal and MCrAlY coating were present, along with some iron oxide on the surface layers—indicating high fuel quality. Internal oxidation in the blade’s midsection cooling area, which operates at elevated temperatures, was particularly pronounced. The quantity of oxidation products observed in both the blade and coating suggests an extended service life, attributable to the high-quality fuel. From an industry perspective, the extent of oxidation and the persistence of the β Ni-Al phase in the coating imply remaining coating life and the potential for life extension under comparable operating conditions.</p>

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Degradation and Internal Oxidation of MCrAlY Coating in an Industrial Turbine Blade: An Investigation

  • 期刊论文

  • 发表日期：

    2025年8月14日

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  • Soroosh Cheraghzadeh,
  • Alireza Gholami Poshtahani,
  • Hassan Abdollah-Pour

摘要

In this study, a gas turbine blade made of IN738LC with a MCrAlY coating (Co-32Ni-21Cr-8Al-0.5Y), which had been in service for 33,000 h at high temperatures, was examined for corrosion and oxidation. The turbine operated at a turbine inlet temperature of 1075 °C, using natural gas fuel primarily composed of methane and butane. The analysis focused on three regions: the leading edge airfoil surface and internal cooling passages in the top, middle, and near-platform sections—corresponding to temperature zones of approximately 800, 900, and 700 °C, respectively. Investigations were conducted using field emission scanning electron microscopy (FE-SEM) and energy-dispersive x-ray spectroscopy (EDS). The results showed that the morphology and cross-sectional features of coating degradation and internal oxidation in the cooling regions aligned with findings from other studies conducted under similar temperature conditions. No corrosion products related to sulfur or alkaline salts were identified; instead, only typical oxides originating from the base metal and MCrAlY coating were present, along with some iron oxide on the surface layers—indicating high fuel quality. Internal oxidation in the blade’s midsection cooling area, which operates at elevated temperatures, was particularly pronounced. The quantity of oxidation products observed in both the blade and coating suggests an extended service life, attributable to the high-quality fuel. From an industry perspective, the extent of oxidation and the persistence of the β Ni-Al phase in the coating imply remaining coating life and the potential for life extension under comparable operating conditions.