Electroplating of Nickel by Jet Flow Method of Electrolysis

Nickel was electroplated by using a jet flow device. For the normal Watts bath (containing 240g/l of nickel sulfate, 45g/l of nickel chloride, and 30g/l of boric acid at pH=4), the maximum available current density (im) was found to be 90Amp/dm2 at 45°C or 180Amp/dm2 at 60°C when the electrolyte was supplied at a jet flow rate of 200cm/sec. (average value in nozzle).At higher current densities, deposition of nickel was perfectly restrained.The deposition rate attained to its maximum value (not limiting current value) at Ep (about -1.5V vs SCE), followed by a marked decrease at less noble potentials.The effects of pH, flow rate, and nickel concentration on im were discussed with respect to codeposition rate of hydrogen and the resultant increase of pH in the diffusion layer around the cathode.No remarkable difference in im was observed between the Watts bath and sulfamate bath, both of which were of the same concentration of nickel.