NATURE OF THE PASSIVE FILM FORMED AT A ZINC ANODE IN ZINC-NICKEL CONTAINING SOLUTIONS

The main aim of this study was to obtain information about the nature of the passive him formed on the zinc anode surface in Ni-containing s olutions by chronopotentiometry, SEM, X-ray microanalysis, XPS and SIM S. It was shown that, with an external anodic current, passive film fo rmation was a result of space-sharing anodic and cathodic reactions du e to local Ni or Zn-Ni alloy electrodeposition. As a result, a film of two layers was formed on the Zn anode: Zn substrate\2Ni(x)Zn (x > 1) + Zn(OH)(2)NiZn + Zn(OH)(2). At the rest potential a one-layer film wa s formed consisting of Zn substrate\2Ni(x)Zn + Zn(OH)(2). (C) 1998 Els evier Science S.A. All rights reserved.