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Compatibility of Wrought Superalloys with Supercritical CO2

by Bruce A Pint
Publication Type
Conference Paper
Book Title
Proceedings of the 10th International Symposium on Superalloy 718 and Derivatives
Publication Date
Page Numbers
239 to 247
Publisher Location
Cham, Switzerland
Conference Name
10th International Symposium on Superalloy 718 and Derivatives
Conference Location
Pittsburgh, Pennsylvania, United States of America
Conference Sponsor
Conference Date

Supercritical CO2 (sCO2) power cycles, particularly direct-fired cycles, have the possibility of revolutionizing clean fossil energy with peak temperatures above 700 °C and wrought precipitation strengthened alloys like Haynes 282™ for structural components. At temperatures <650 °C, it would be desirable to use less expensive alloys, however, steels are known to be susceptible to carburization. Laboratory 300 bar sCO2 autoclave results were collected on a range of alloys including less expensive Ni-based alloys like 825 compared to advanced austenitic steels like alloy 709 at 600 °C. Both alloys 825 and 709 formed thin, protective Cr-rich oxides after 1,000 h. Alloy 825 also was exposed for 1,000 h in sCO2 at 800 °C and compared to a range of Ni-based alloys. Comparing alloys 625, 825, and 282, the mass gain increased with increasing alloy Ti content under these conditions. High Al superalloys did not perform significantly better under these conditions at 800 °C.