High temperature oxidation of Ni alloys in CO2 containing impurities

Next-generation power systems require structural alloys resistant to high-temperature oxidation in CO2 containing combustion impurities. Here we evaluate the oxidation performance of several commercial Ni alloys exposed to 95%CO2-4%H2O-1%O-2, with/without 0.1% SO2, at 750 degrees C and 1 atm. All alloys formed protective chromia layers and showed no signs of carburization or sulfidation, and minimal chromia volatilization. The microstructural evolution of the alloy surface, secondary oxidants, and minor alloy additions all played a role in promoting protective chromia formation/growth. The results show that Ni alloys are promising candidates for high-temperature portions of next-generation CO2-based power systems.