Akihiro Nagatani’s research while affiliated with Tohoku University and other places

Oxygen activities in liquid iron deoxidized with aluminium were measured at 1873 K, using a mullite electrolyte having a Cr-Cr2O3 reference mixture. These results were compared with those obtained using commerical tube-type ZrO2-8 mol% MgO and plug-type ZrO2-9 mol% MgO probes, along with oxygen activities calculated from analysis. Oxygen activities from EMF measurements using mullite and plug-type probes were found to be in agreement with those calculated from the Al/Al2O3 equilibrium and those estimated from analyzed oxygen contents. Polarization effect due to electrochemical oxygen transport was observed in a commerical tube-type ZrO2-based probe. Supersaturation in liquid iron deoxidized with aluminium was also measured at 1873 K.

A coulometric titration technique was used for the determination of the parameterP , defined as the oxygen partial pressure at which the ionic conductivity and n-type electronic conductivity of the electrolyte are equal, for mullite and 9 mol% MgO stabilized zirconia electrolytes in the temperature range 1674–1921 K. The results ofP for mullite and ZrO2-9 mol% MgO were log(P /101 325 Pa)=54.32–137000/T and log (P /101 325 Pa)=27.16–75500/T, respectively. The results for low oxygen activities in liquid iron are discussed on the basis of the present results forP values.