Screening for Al2O3 failure in MCrAlY APS coatings using short-term oxidation at high temperature
Résumé
The high temperature oxidation behavior of an APS processed γ–β NiCoCrAlY coating was investigated at 1150 °C. Ultrathin freestanding coating specimens ranging from 16 to 240 μm in thickness were tested for short-term oxidation time (< 300 h). Intrinsic chemical failure (InCF) occurred after the full consumption of Al, and resulted in Cr2O3 growth and CrN precipitation at the Al2O3/alloy interface. Mass gain slowed down after InCF, even leading to a mass loss associated with the volatilization of Cr2O3. InCF occurred after [10–20] h and [20–100] h for the ∼ 21 μm and ∼ 31 μm-thick specimens, respectively. Severe metal recession was observed after InCF.
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