The early stages of the oxidation of a 9% chromium steel in carbon dioxide studied by Auger electron spectroscopy

The early stages of the oxidation of 9% Cr steel in carbon dioxide at atmospheric pressure and 773 K have been studied by use of Auger electron spectroscopy. The surface of the sample was monitored throughout the oxidation process without changing the environment other than to evacuate the system for a short period so that the Auger spectrum could be recorded. Sulphur was found to be an important participant in the early stages of oxidation and an oxide film containing iron was formed. Chromium was not detected in this oxide, indicating that its presence in the alloy is not conducive to the formation of a protective Cr2O3 layer. The mechanism of oxidation was similar to that of pure iron under the same conditions. (Auth.)