5 - Corrosion and mass transfer in liquid metal systems

Abstract

Corrosion and mass transfer phenomena that determine the choice of structural materials and operating parameters of the liquid metal coolant circuits are dealt in this chapter. The driving forces for the corrosion are first described. Since the phenomenon is unique for each coolant structural materials combination, the experimentally observed characteristics and the underlying mechanism in each case are presented: (1) oxygen-assisted general corrosion as well as carbon transport in sodium-steel systems, (2) corrosion of austenitic and ferritic steels and vanadium alloys in liquid lithium systems, (3) corrosion of steels in liquid lead and lead-bismuth eutectic alloy, and (4) corrosion of austenitic and reduced activity ferritic-martensitic steels in liquid lead-lithium eutectic alloy system. Methods adopted to mitigate corrosion in the lead and lead-bismuth eutectic systems, viz. control of dissolved oxygen in liquid metal, choice of composition of the steels, and microalloying of the surface with oxide formers such as aluminum are described. Since wetting of the base material by liquid metal is the prerequisite for corrosion and mass transfer to occur, observed characteristics of wetting by each liquid metal coolant are described.