CONTROL OF THE ALUMINUM-OXYGEN REACTION IN PURE IRON MELTS

Modified electrochemical oxygen sensors based on CaO-doped ZrO2 and Y2O3-doped ThO2 were developed and applied to study the aluminium-oxygen reaction in pure liquid iron with special regard to the provision of reliable experimental conditions and the attainment of true chemical equilibrium. The sensors represent valuable tools particularly for EMF long-term measurements over several hours. At 1600 degrees C, values of the constant K'(Al-O) = 9.77.10(-15) and of the interaction parameters e(O)(Al) = -5.54 and e(Al)(O) = -9.35 were determined. When Fe-O-Al melts are covered with a slag phase at an activity a(Al2O3) < 1, e.g., CaO-saturated CaO-Al2O3 slag, the Al-O relationship in the iron may nevertheless be controlled by an equilibrium oxide phase at an activity a(Al2O3) = 1, presumably represented by inclusion particles crossing of pure Al2O3.