Activation and passivation of zirconium by electrochemical treatment in aqueous and non-aqueous chloride solutions

Factors that affect the activation and passivation of Zr in aqueous, alcohol, and formamide chloride solutions are studied. The passive state of Zr in these solutions is discussed in terms of concurrent adsorption of solvent molecules and chloride ions. Species of intermediate valence can impact the anodic dissolution of Zr and the formation of a finely divided black deposit of alpha -Zr on its surface. For aqueous solutions, conditions that ensure high precision of the electrochemical dimensional treatment and good quality of Zr surface are found. A formamide-based electrolyte for electropolishing Zr is developed.