Temperature-Dependence of Corrosion of Ni-Based Superalloys in Hot CO2-Rich Gases Containing SO2 Impurities

• Published in: JOM (1989) Vol. 72; no. 5; pp. 1822 - 1829
• Main Authors: Oleksak, Richard P., Tylczak, Joseph H., Holcomb, Gordon R., Doğan, Ömer N.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-05-2020; Springer Nature B.V; Springer
• Subjects: Advancing Development and Application of Superalloys; Alloy systems; Alloys; Carbon dioxide; Chemistry/Food Science; Coal; Corrosion; Corrosion resistance; Earth Sciences; Electric power generation; Engineering; Environment; Gases; Heat exchangers; High temperature; Impurities; MATERIALS SCIENCE; Nickel base alloys; Performance evaluation; Physics; Power plants; Scale (corrosion); Sulfur dioxide; Superalloys; Temperature; Temperature dependence
• ISSN: 1047-4838; 1543-1851
• DOI: 10.1007/s11837-020-04081-z

Future power plants will require Ni-based superalloys resistant to high-temperature corrosion in CO
2
-rich environments containing impurities. In this work, several commercially available Ni-based alloys (617, 230, 625, 263, 740H) were exposed at 600°C, 650°C, 750°C and 1 atm to 95% CO
2
, 4% H
2
O, 1% O
2
without/with 0.1% SO
2
to simulate compositions expected in a direct-fired supercritical CO
2
power cycle. The results indicate no effect of SO
2
at 750°C, a small negative effect at 650°C, and a large negative effect at 600°C. Alloys exposed at the higher temperatures (650–750°C) formed thin Cr-rich oxide scales, whereas the lowest temperature (600°C) resulted in thicker scales consisting of non-protective oxides and sulfates. Thermodynamic analysis indicates this increased corrosion is associated with a transition in the stable compounds in contact with the gas. Understanding the factors that affect this transition will aid in the selection or design of alloys for future CO
2
-based power systems.