PLATING METHOD OF NI, NI-ZN ALLOY OR NI-ZN-CO ALLOY

摘要

PURPOSE:To control the concn. of the plating solution for a long time and to enable stable plating by removing the increment of the hydrogen ion concn. from the plating bath by use of a diffusion dialysis tank. CONSTITUTION:In the process of plating, the hydrogen ion concn. in the plating tank B increases. When the initial concn. of sulfuric acid in the cathode room (b) of the electrolysis tank A is set low, the hydrogen ion concn. in the dialysis tank C differs between two rooms separated by an anion-exchange membrane. This causes diffusion of sulfuric acid to the room of lower concn. as shown by an arrow D in the figure. Thereby, the desulferized soln. returns to the plating tank B as shown by an arrow E, while the soln. into which sulfuric acid diffuses returns to the cathode room (b) of the electrolysis tank A as shown by an arrow F. Since the anion-exchange membrane 4 is used in the dialysis tank C in this process, Ni, Zn or Co ions hardly move to the room of lower concn.