The Effect of Plating Variables on Zinc-Nickel Alloy Electrodeposition

Abstract

SummaryAcid chloride based solutions, pH approximately 5.5, were used for the deposition of zinc-nickel alloy coatings. The initial objective of this research project was to study the effects of variations in the nickel content of the plating solution and current density on the deposit composition. Subsequently the effects of variations in solution temperature, pH and agitation on deposit composition and cathode current density were evaluated for the solution containing 15 g/l nickel. The influence of plating conditions on appearance, microhardness and macro throwing power were also studied. When corrosion behaviour, which has been reported earlier, was also taken into account, the following plating solution formulation and operating conditions were considered to give the optimum results: ZnCl2 (62.5 g/l), NH4Cl (200.0 g/l), NiCl2.6H20 (60.7 g/l), which is equivalent to 15 g/l nickel metal, Ammonia (25%, 50.0 ml/l), Temperature: 25.0 ± 0.5°C, pH: 5.5 ± 0.2, Current Density: 3.0 A/dm2, Anode: Pure Zinc, Agitation: Air. Additional informationNotes on contributorsA. AbibsiDr. A. Abibsi has been carrying out postgraduate research on zinc alloy electrodeposition at Aston University.J. K. DennisDr. J. K. Dennis is a senior lecturer in the Department of Mechanical and Production Engineering at Aston, where he is actively involved in many aspects of surface finishing research. He serves on several IMF committees.N. R. ShortDr. N. R. Short is a lecturer in civil engineering at Aston, and has a particular research interest in corrosion problems.