High-temperature cyclic oxidation behaviour of Pt-rich γ-γ' coatings. Part I: Oxidation kinetics of coated AM1 systems after very long-term exposure at 1100 °C

The cyclic oxidation behaviour of several compositions of Pt-rich γ-γ' bond-coatings on AM1 superalloy was studied at 1100 °C and was compared to the β-(Ni,Pt)Al coated and uncoated superalloy. AM1 superalloy exhibited an outstanding performance due to an optimized Hf doping and a low sulfur content. The Pt-rich γ-γ' bond-coatings showed a better cyclic oxidation resistance than the reference system with a β-(Ni,Pt)Al coating. Aluminium addition during fabrication was found to be beneficial to improve the oxidation behaviour of Pt-rich γ-γ' bond-coatings. Their breakaway resulted from an insufficient aluminium content below the TGO whereas the reference system suffered from rumpling.