Dual-Al-source designed oxidation resistant coating for Ni-based superalloy: high-temperature oxidation behavior at 1200 ℃

Nickel (Ni)-based superalloys for aircraft hot-section components suffer from severe oxidation at 1200 °C. Current protective coatings fail to provide long-term protection due to insufficient Al supply. To address the critical challenge, a dual-Al-source oxidation resistant coating was prepared on Ni-based superalloy via the Inorganic Precursors Conversion (IPC) method. The large NiCrAlY particles (15 μm) provided oxidation resistance and regulated thermal expansion compatibility, whereas fine Al particles (3 μm) filled the gaps to compensate for aluminum content. After 30 h of oxidation at 1200 °C, the coated alloy exhibited a mass gain of 0.445 mg·cm⁻², which was 89 % lower than that of the bare alloy. Moreover, the coating evolved into an “Oreo-like” trilayer structure composed of the multiphase oxides outer layer, dense Al₂O₃ barrier interlayer, and interfacial Cr₂O₃ layer. The long-term oxidation resistance of the dual-Al-source coating was governed by its sufficient Al reservoirs, which promoted the formation of the dense Al₂O₃ layer that acted as a barrier to inhibit both inward oxygen transport and outward cation diffusion.