OXIDATION OF MILD AND LOW-ALLOY STEELS IN CO2 BASED ATMOSPHERES

The behaviour of pure Fe, a rimming steel and three low-alloy steels has been fully characterized in CO2 containing small amounts of CO and H2O at 500 °C. Emphasis has been given to the provision of basic data to assist in the identification of the mechanisms responsible for the formation of non-protective oxide together with linear oxidation rates. Essential conditions for non-protective oxidation are the presence of water vapour and a high pressure of CO2. The adverse influence of water vapour is enhanced by deposits of Au, C, and Pt on the metal. C may be transferred from the gas phase as several per cent of the O transfer by the Boudouard or a similar reaction, utilizing CO produced by prior oxidation of the metal with CO2. Two tentative mechanisms are advanced to explain non-protective oxidation. © 1968.