Mixed molten salts hot corrosion behavior of nickel-based single-crystal film-cooling holes under static air at 900 °C

Hot corrosion behavior of Ni-based single-crystal turbine blade film cooling holes at 900 °C was investigated in three mixed salts and compared with a sample without holes. The results indicate that the hot corrosion degree in the 75% Na₂SO₄ + 15% NaCl+10% NaVO₃ is the most serious, followed by 75% Na₂SO₄ + 25% NaCl, and 75% Na₂SO₄ + 25% NaVO₃ is the least. Moreover, analysis reveals a synergistic interaction among the three mixed salts: S acts as the primary corrosive species, while Cl and V function as secondary accelerants of hot corrosion. Electrical discharge machining (EDM) may change the element distribution around the holes, leading to the formation of a more stable Al₂O₃ layer around the holes after hot corrosion, which may contribute to the lower corrosion severity observed near the hole region.