Electrochemical processes during plating Fe powder particles by Ni and Ni/Cu coating in the fluidized bed

Ni electrodeposition on Fe powder was studied with respect to an inhibiting adsorbed hydroxycomplex layer. Its elimination was done in three possible ways: by increasing the rotation speed of the circular stirring of the susp ension, by chemical dissolution of the adsorbed layer during interrupted el ectrolysis, and by addition of a complexing agent - sodium citrate into the electrolyte. The simultaneous deposition of a Cu/Ni coating was enabled by proper electrolyte composition as to the ratio of both metallic compounds and by the addition of a suitable complexing agent. The Cu/Ni ratio was inf luenced, beside electrochemical parameters, also by the particle size of th e Fe powder and by the suspension density. Increasing the suspension densit y supports the deposition of Ni, and increasing the particle size supports the deposition of Cu.