Effect Of Thermal Cycling On Oxidation Of Nickel Based Superalloys In Presence Of Aggressive Ions

Superalloys are considered potential candidates to be used in high temperature applications. In the present study, experimental measurements of high temperature oxidation in presence of aggressive ions of Nickel base superalloy (Hastelloy-X) have been carried out at 700 degrees C, 800 degrees C and 900 degrees C for exposure time durations of 1, 3, 5, 10, 20, 50 and 100 hours. The oxidation behavior of superalloy Hastelloy X in the presence of aggressive media, normally, NaCl and Na2SO4 is to identify the surface scales that have been formed. After oxidation experiments, the samples were characterized using Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) to find out the formed phases. The results showed that the major corrosion products formed are Nickel Chromites NiCr2O4 with some Chromium Cobalt Oxide CoCr2O4 spinels in additions to chromium oxide Cr2O3. The obtained results of Hastelloy X were compared with the results achieved previously for Inconel 617. In this study, the activation energy of Hastelloy X was estimated and found to be Ea = 57.84 KJ/mole.