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.