Monitoring pH and Corrosion Potentials in High Temperature Aqueous Environments

A zirconia membrane electrode that responds to pH can serve admirably as a pH sensor in high temperature aqueous systems. Alternatively, under conditions of known, stable pH, the sensor may be used as a reference electrode for monitoring corrosion and redox potentials. Data are presented to illustrate the thermodynamic reliability and stability of such a sensor at elevated temperatures. An example of corrosion potential monitoring, including correlations with related ambient temperature measurements of pH, oxygen and hydrogen concentrations, and water resistivity, is given.