Development of an Electrochemical Technique for the Determination of Chromium Oxide Activities in Molten Slag Systems

摘要

Some of the problems and limitations in the determination of electrochemical activity are analyzed. It is shown quantitatively that the determination of chromium oxide activities by electrochemical techniques can provide meaningful results only if a solid electrolyte with a very low Pe value (the partial pressure of oxygen at which the ironic conductivity and the n-type electronic conductivity are equal) is used. These findings led to the development of an electrochemical technique based on the use of an yttria-stabilized thoria electrolyte. However, since the delivery of the thoria electrolytes was delayed, an experimental evaluation of the technique was carried out using magnesia-stabilized zirconia electrolytes. Chromium oxide activities were measured in (CaO+SiO2+CrxO) slags at 1400 C and compared with those determined by other workers. The results show that the technique is feasible, and that it should be possible to determine chromium oxide activities very accurately by using yttria-stabilized thoria electrolytes. It is therefore recommended that the project should be continued as soon as thoria electrolytes become available.