The use of Fe-Cr-Ni alloys in steam generator systems of light water-cooled nuclear power plants has stimulated interest in developing electrochemical techniques for use in water environments at temperatures up to at least 316°C. As pointed out by Jones and Masterson(1), many difficulties have been encountered in this area. However, with the development of reliable internal silver/silver chloride reference electrodes [e.g., Indig and Vermilyea(2) and Magar and Morris(3)], it is no longer necessary to plot electrochemical data obtained at temperatures above 100°C on an arbitrary potential scale. Accordingly, attention is now being focused on the actual electrochemical techniques to be used. Five different techniques have been utilized in the few published electrochemical corrosion studies at temperatures above 100°C. Several workers(4-7) have used linear polarization methods to calculate corrosion rates while others(8-14) have used the potentiostat to determine anodic polarization curves. Cowan and Staehle(10) have correlated potential decay measurements with potential/pH diagrams and related current decay measurements to surface film characteristics. Finally, Hubner et al (9) and Theus(14) have utilized controlled potential methods in conjunction with anodic polarization curves to produce stress corrosion cracking in high temperature aqueous environments.
