Oxidation of alloys for energy applications in supercritical CO2 and H2O

• Experiments were conducted in supercritical CO2 and H2O at 730 °C/207 bar for 500 h on 347H, 282 and 625.
• Ni-base alloys in supercritical CO2 did not exhibit a significant change in oxidation with pressure.
• Austenitic stainless steels in supercritical CO2 and H2O responded similarly with an increase in oxidation with pressure.

To facilitate development of supercritical CO2 (sCO2) power plants, a comparison of the oxidation behavior of austenitic stainless steels and Ni-base alloys in sH2O and sCO2 were made. Experiments were conducted at 730 °C/207 bar (sCO2) and 726 °C/208 bar (sH2O). Ni-base alloys in sCO2 did not exhibit much change with pressure. Ni-base alloys in sH2O had an increase in corrosion rate and the log of the parabolic rate constant was proportional to pressure. Fine-grain austenitic stainless steels in sCO2 and sH2O were both less protective with pressure as the dense protective chromia scale was replaced with faster growing Fe-oxide rich scales.