High-temperature oxidation of Haynes 282 microtubes in CO2

ABSTRACT The oxidation characteristics of Haynes 282 microtubes measuring 1 mm in diameter and 200 µm thick exposed to CO2 at elevated temperature are reported. After 215 hours at 700°C and 1 atm, a thin, protective chromia scale accumulates up to 2.03 µm from the outer surface, approximately 1% of the thickness, and internal aluminum oxidation is observed 2.59 µm from the inner surface. The results suggest that oxidation is limited by oxygen diffusion through the growing oxide scale layer. The average grain size in the microtube is 10 µm, and it decreases to 5 µm closer to the inner surface. Severe plastic deformation and variable dynamic recovery and recrystallization from the manufacturing process were observed throughout the microtube. Overall grain size and distribution in the microtube were found to be independent of thermal exposure, despite the occurrence of recrystallization. The superalloy microtube geometry shows promising performance in high-temperature thermal applications.