Pre-Oxidized High-Velocity Oxygen Fuel Sprayed CoNiCrAlY Coating as An Environmental Barrier Against Ammonia Corrosion for Pure Ammonia Combustion Gas Turbines

Abstract In this work, we investigated the potential of a dense oxide layer in resisting ammonia corrosion. First, the degradation behavior of Hastelloy X substrate and HVOF sprayed CoNiCrAlY coating (as-sprayed condition) was studied in an ammonia gas flow environment. The coating was then heat-treated in air to pre-oxidize the surface, enabling the formation of a dense and stable oxide layer. Thereafter, the degradation characteristics of the pre-oxidized coating was investigated under the same environment. The mechanisms of degradation and corrosion resistance of the materials are elucidated.