Electrodeposition of Copper‐Nickel Alloys from Citrate Solutions on a Rotating Disk Electrode: I . Experimental Results

Abstract

Steady‐state polarization measurements on stationary and rotating disk electrodes were performed in Cu‐Ni‐citrate plating baths as well as in single metal ion‐citrate solutions. The polarization curves were used to identify the different electrode reactions occurring during the plating process. Five electrochemical reactions were found dominant in different potential regions. They were the reduction of hydrogen ion from the dissociation of hydrogenated citrate ion, oxygen reduction, copper deposition, nickel deposition, and reduction of water. Codeposition of Cu‐Ni alloy occurred in a fairly narrow electrode potential region (−1.0 to −1.2V vs. SCE), where the effects of the side reactions were relatively small. A Levich analysis of the rotating disk data was used to determine the overall kinetic and mass transport parameters of the Cu‐Ni alloy electrodeposition process. Finally, compositional and morphological analyses of the alloy plated at constant potentials were also performed.