Electrodeposition of nickel-cobalt alloys from sulfate acid baths

In this work, nickel-cobalt electrodeposition under galvanostatic conditions was investigated. Ni-Co alloy was electrowon from an acid sulphate bath containing 40 g/L Ni and 2-8 g/L Co. The effect of electrolyte composition, current density, temperature, solution pH and presence of buffers such as H3BO3 and (NH4)(2)SO4 on Co content of the binary alloy has been investigated. In particular, current densities ranging from 180 to 400 A/m(2) and temperatures ranging from 27 to 60degreesC were tested. The composition of Ni-Co alloys may be diversified through the selection of process parameters. The experiments show that the highest cobalt content of the alloy is reached by using a buffer free electrolyte without solution pH control. Though, in these conditions, the most homogeneous, fine and regular deposit morphology is obtained, energy requirements are the highest in tests lasting just two hours.