Effect of pre-oxidation on coke formation and metal dusting of electroplated Ni{sub}3Al-CeO{sub}2-based coatings in CO-H{sub}2-H{sub}2O

摘要

Pre-oxidation was introduced to improve the resistance of electroplated pure, 5 μm CeO{sub}2-dispersed, and 9-15 nm CeO{sub}2-dispersed Ni{sub}3Al coatings to coke formation and metal dusting in 24.4%CO-73.3%H{sub}2-2.3%H{sub}2O at 650℃. Coke formation and metal dusting of pre-oxidized Ni{sub}3Al-based coatings were retarded up to 200 h owing to a thin Al{sub}2O{sub}3 scale induced during preoxidation. The long-term effectiveness of pre-oxidation nonetheless depended on the integrity of Al{sub}2O{sub}3 scale. The pure Ni{sub}3Al coating suffered severe spallation after pre-oxidation and thereby showed the worst long-term resistance. Two pre-treated 9-15 nm CeO{sub}2-dispersed Ni{sub}3Al coatings exhibited the best long-term resistance to carbon attack because nano-CeO{sub}2 particles maintained a full coverage of Al{sub}2O{sub}3 scale on the coatings. Two 5 μm CeO{sub}2-dispersed Ni{sub}3Al coatings showed significant spallation after pre-oxidation because of an overdoping effect and experienced coke formation and metal dusting during long-term exposure.