ELECTRODEPOSITION OF NI-W-B AMORPHOUS-ALLOYS

Partial polarization curves at the glassy carbon rotating disc electro de have been used to study the electrodeposition of Ni and Ni-W alloy from citrate-containing solution. For deposition of Ni-W alloys, the p artial polarization curves indicate diffusion control for nickel reduc tion and stoichiometric limitation for tungsten deposition by the comp osition of the alloy. Plating experiments show that current efficiency of the electrodeposition and composition of the resulting alloy depen d on the parameters of the electrolysis. The best conditions for elect rodeposition of the alloy Ni-W-B are current density of 45-50 mA cm(-2 ), temperature of 60-70 degrees C, Ni(II) concentration of 20-25 mM, a nd pH 8.5. Pulsed galvanostatic plating at 1 Hz increased slightly the current efficiency. The concentration of Ni(II) in the solution can b e self-regulated by using a nickel bipolar electrode in the cathode co mpartment.