Abstract: | Oxygen activities in Fe-O-Cr melts, equilibrated with chromium oxide, were determined as a function of chromium content by EMF measurements using ZrO2(CaO) plug-type sensors with a Cr-Cr2O3 reference. Plug-type sensors with or without Cr2O3 saturator were used in the experiments. From the experimental results values for the activity coefficient fO and the interaction parameters and were evaluated. Raoultian chromium activity features a slight positive deviation from ideal solution behaviour in the temperature range from 1550 to 1650°C. Taking into account the calculated interaction parameters, the equilibrium constant KCr-O was redetermined at 1550 to 1650°C. In comparison with previous studies a better agreement was obtained with existing thermochemical data. |