Abstract
Ag(s)/Ag~2~SO~4~(l) reference electrodes for use in hot corrosion research were fabricated and their properties were studied at 927Β°C (1200Β°K). The McDanel^TM^ MV 30 mullite tube was used as sheath of the reference electrode and concentrations of the tested electrolytes were varied from 0.1 to 10 m/o Ag~2~SO~4~ (l) + Na~2~SO~4~ (l). 10 m/o Ag~2~SO~4~ was always used as electrolyte in the reference electrode. The working electrodes with less than 2 m/o Ag~2~SO~4~ showed marked potential drift as the Ag~2~SO~4~ concentration was lowered, showing poor potential stability. However, the initial values of cell voltages obeyed Nernstian behavior for all range of Ag~2~SO~4~ concentrations in the working electrodes, which showed that Ag(s)/Ag~2~SO~4~(l) electrodes behaved reversibly. Galvanostatic polarization was performed on a pair of 10 m/o Ag~2~SO~4~ reference electrodes to test the reversibility. The polarizability was 3.5 mV/10 ΞΌA with no hysteresis loop on the polarization curve, showing that the reversibility was satisfactory. The potential of gold electrode in molten Na~2~SO~4~ was measured under pure oxygen atmosphere with 10 m/o Ag~2~SO~4~ electrode as a reference potential. The results showed that the potential of gold electrode could be explained by the 2 Na + SO~3~ + 1/2 O~2~ β Na~2~SO~4~ cell reaction.