Comparison of the cyclic oxidation behavior of a low expansion Ni + CrAlYSiN nanocomposite and a NiCrAlYSi coating

• Ni + CrAlYSiN and NiCrAlYSi coatings improved the cyclic oxidation resistance of K417.
• Crack/spalling of thermally grown oxide (TGO) of NiCrAlYSi coatings occurred.
• Neither spallation nor cracking was observed on the Ni + CrAlYSiN coated specimens.
• Interdiffusion between the coatings and the substrate was observed.
• An AlN layer inhibited interdiffusion between the Ni + CrAlYSiN coatings and substrate.

Ni + CrAlYSiN nanocomposite coatings and NiCrAlYSi coatings were prepared on a nickel-based superalloy K417 by vacuum arc evaporation. Both coatings exhibited excellent cyclic oxidation resistance at 1000 °C for 200 1-h cycles. Cracking/spallation of thermally grown oxide (TGO) scale occurred only on NiCrAlYSi coatings, due to the lower thermal stresses level in the TGO on Ni + CrAlYSiN coatings. An hcp-AlN interlayer eliminated the interdiffusion between the nanocomposite coating and substrate. The thickness of the TGO scale on NiCrAlYSi coatings was twice that of the scale on the AlN/Ni + CrAlYSiN coatings, probably due to the crack and healing effect.

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