Study of the dendritic growth of Ni-Co alloys electrodeposited on Cu substrates

Abstract

Ni-Co alloy deposits and their parent metals were formed on Cu substrates by electrolysis under different current densities applied in the galvanostatic regime. A quantitative scanning electron microscopy technique was employed to study the morphology and surface roughness of the obtained deposits. The structure of the deposits is governed by the nature of depositing ions and quantity of evolved hydrogen. The cauliflower morphology and the highest mean surface roughness values are the results of electrodeposition from the Ni containing bath. The structure of the Co deposits formed under the same conditions and determined by the formation of the hexagonal close-packed phase results in a more uniform grain size distribution and formation of smoother platelet deposits. The mean surface values of the parent metals are independent of the current density. The dendritic growth is a special case of a structure formed only in the Ni-Co alloy deposition at selected, high current densities of 220 and 400 mA cm-2. The dendrites obtained at a higher current density of 400 mA cm-2 have shown more developed structures with smaller dendrites that have more pronounced secondary branch and high order branches. © 2010 The Electrochemical Society.