Corrosion of nickel,iron, cobalt and their alloys in molten salt electrolytes

The processes of high-temperature corrosion, anodic dissolution and passivation of nickel, iron, cobalt and their alloys are reviewed to reveal the progress in understanding the reaction mechanisms defined in the last two decades. In the first part, the procedures of thermodynamical analysis of corrosion processes by potential — pO^2– diagrams are outlined. The second part is devoted to the electrochemical corrosion, anodic dissolution and passivation of the metals studied, the reaction mechanisms and composition of the corrosion layers formed. The effect of the alloying elements on the corrosion resistance and anodic behaviour of the base metal is treated in the third part. A brief summary of the kinetics of the so-called hot corrosion of the studied metals and their alloys in contact with thin molten salt films and aggressive atmospheres is then given. Finally, some conclusions are drawn and some future trends of investigation are indicated.