High-temperature Corrosion and Oxidation Behavior of Nickel/Cobalt-based Superalloys Operating with Hydrogen Mixtures

Abstract In turbomachinery systems, combustion with excess air and the use of hydrocarbons result in the generation of a combustion environment characterized by a high concentration of oxygen, nitrogen, CO2 and H2O, along with other combustion compounds. The utilization of syngas or molecular hydrogen as a fuel source has been observed to result in an increase in the quantity of water that interacts at elevated temperatures with the turbine materials. In the context of the transition to low-emission energy sources, it is challenging to predict the long-term effects on component durability using standard material testing. In this work the focus is therefore on the study and execution of innovative (also accelerated) high-temperature corrosion and oxidation tests at a temperature of 982°C, in dry and wet air, of two Ni/Co-based superalloys typically used in turbogas machines operating with hydrogen mixtures. Micrographic analysis, including scanning electron microscopy (SEM) coupled with Energy-dispersive X-ray spectroscopy (EDS) were conducted. The final results are described highlighting the different oxidation behavior of these two alloys families. Future aim will be to identify a robust and reliable oxidation damage modeling approach for both chromia-former and alumina-former high temperature alloys.