High temperature oxidation and corrosion of boiler materials

The study aims to the development of methods and models for the assessment of material performance in boilers and use of mixed fuels with combustion gas species like H2O, HCl or SO2. Gas phase oxidation tests at elevated temperatures under different atmospheres were carried out for selected steels. Formed oxide scales were characterised using EDS/SEM, and mass changes were measured for the exposed samples. Thermodynamic stability calculations simulating oxidation correspond quite well to the oxide structures formed in laboratory exposures for specified steel compositions. The results from laboratory exposures were also used to model the oxidation kinetics. The results show that oxidation kinetics and mechanism are strongly dependent on temperature and gas species like H2O, HCI and SO2. A further goal is to combine thermodynamic calculations and kinetic measurements for oxidation simulation to get an efficient tool for prediction of corrosion for specific steel types and combustion conditions.