Effect of H2O and CO2 on the Oxidation Behavior and Durability at High Temperature of ODS-FeCrAl

Cyclic oxidation testing was conducted on alloy MA956 and two different batches of alloy PM2000 at 1,100 and 1,200 A degrees C in different atmospheres rich in O-2, H2O and CO2. Compared to 1 h cycles in dry O-2, exposure in air + 10 vol.% H2O resulted in an increase of the oxidation rate and a decrease of the time to breakaway for all alloys at 1,200 A degrees C, and a faster consumption of Al in the MA956 alloy. One hour cyclic testing in 49.25 % CO2 + 50 % H2O + 0.75 % O-2 had a smaller effect on the oxidation rate but led to increased formation of voids in alloy MA956, which had an impact on the alloy creep resistance. At 1,100 A degrees C, exposure in 50 % CO2 + 50 % H2O resulted in significant oxide spallation compared with oxidation in air, but this was not the case when 0.75 % O-2 was added to the CO2/H2O mixture as a buffer. The control of impurity levels drastically improved the oxidation resistance of PM2000.