Changes in the Depth Profile of Surface Films on Alloy 600 in High Temperature Water

Abstract

The aqueous oxidation of Alloy 600MA (mill annealed) and TT (thermally treated) materials in acidic, neutral and basic pHs (pH 4.5, 7, 10 and 14) under low and high dissolved oxygen concentrations (DO₂<5ppb, ≅4ppm) has been studied using a once-through (refreshed) autoclave and Auger electron spectroscopy. The in-depth profile of composition of oxide films on Alloy 600 was measured using an argon sputtering method. Both pH and DO₂ have an effect on oxide film composition and also a change in these parameters is reflected by a change in the film depth profile.