For co-deposition of Zn-Co or Zn-Fe alloys in chloride baths it was found that the transition current density of Zn varied with the deposition process from normal co-deposition to anomalous co- deposition. The value of the transition current density increases with the increasing of Cl~- concentration. However, when Cl~- concentration exceeds 4 mol·dm~(-3), the co-deposition process becomes normal type and the transition current density of Zn disappears. It can be attributed to the existence of Cl~-, which decreases the evolution overpotential of Co and Fe metal, especially for Fe metal.

Key words: ZINC ALLOYS, COBALT ALLOYS, CURRENT DENSITY, SEDIMENTATION