The use of a direct-fired supercritical CO2 (sCO2) power Allam cycle could revolutionize fossil energy as a low-emission power source. However, the carburizing sCO2 environment may limit the use of lower cost steels in the lower temperature portions of the plant because of concerns about embrittlement. Initial studies on representative ferritic-martensitic (FM) steels and conventional and advanced austenitic steels at 450-650°C in 300 bar (30 MPa) sCO2 with and without 1%O2 and 0.1%H2O additions have indicated that sCO2 environments will have lower maximum operating temperatures compared to steam plants. In this study, pack coated steels were evaluated including chromizing and aluminizing. Initial 500-1000 h results showed some benefit of coating especially for the Cr coatings at 600° and 650°C. Characterization included measuring the post-exposure room temperature tensile properties to assess the coating effect on embrittlement typically associated with carbon ingress.

Subject
Energy dispersive X-ray spectroscopy, Coatings, Materials, Carbides, Substrates, Oxides, Oxide formation, Tensile properties, Mass gain, Impurities, Steel, Surface profile, Ductility
Keywords:
supercritical carbon dioxide, steels, impurities, coatings, pack cementation
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2023
Association for Materials Protection and Performance (AMPP)
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