Physical chemistry of corrosion and oxygen control in liquid lead and lead-bismuth eutectic

Corrosion of steel in liquid lead (Pb) and lead-bismuth eutectic (LBE) is an important factor when applying these materials as a process medium. At low oxygen content of the liquid-metal phase, the degradation results mainly from the dissolution of the steel constituents, which may significantly decrease in the presence of a continuous scale of oxides of the steel constituents on the steel surface. In order to facilitate the formation of such a scale, the oxygen content of the liquid metal has to be controlled. Therefore, a method of measuring the oxygen content must be available. This report addresses the thermodynamic fundamentals of steel corrosion in oxygen-containing liquid metals and provides the data on chemical and physical properties which is required for the determination of favourable conditions with respect to the oxygen content and the numerical analysis of the dissolution of the primary steel constituents in oxygen-containing liquid Pb and LBE. Furthermore, the measurement of the oxygen content with electrochemical oxygen sensors and the evaluation of the sensor output is discussed.