On Electrode Polarization of Electrochemical Oxygen Sensor in Liquid Metal Coolants
The paper considers the main provisions of thermodynamic oxygen activity control in liquid metal coolants by the EMF method by means of a two-electrode electrochemical oxygen sensor with a solid oxygenated electrolyte which is in contact with the coolant and at the same time is a working electrode of the sensor. The sensor EMF is proportional to the oxygen activity logarithm. It has been noted that absorption of metallic impurities and oxides on the electrolyte causes polarization of the working electrode, thus reducing the EMF value and deteriorating the oxygen control accuracy. The polarization process was shown to be multifactorial and localized within the limits of double electric layer that results from the difference in the work functions of the contacting phases. The double layer characteristics are presented. The analytical dependence values were calculated for the electron work function from the solid electrolytes and metal oxides.