Electrodeposition and morphology of Ni, Co and Ni-Co alloy powders - Part II. Ammonium chloride supporting electrolyte

Polarization characteristics of the processes of Ni and Co powders and Ni-Co alloy powders electrodeposition from ammonium chloride containing supporting electrolyte and their morphologies are investigated as a function of Ni2+ and Co2+ ions concentrations. It is found that the shape of the polarization curves in all cases is practically defined by the shape of the polarization curve for hydrogen evolution. It is shown that correct polarization curves, as well as the morphology of electrodeposited powders are sensitive to the ratio of Ni2+/CO2+ ions concentration. Characteristic feature of powder particles obtained from chloride containing electrolytes is the presence of cone-shaped cavities. In the case of Ni powder cauliflower and spongy type particles are detected, while Co powder contains only spongy type particles. In all cases of alloy powder formation anomalous type of co-deposition is detected. (c) 2006 Elsevier Ltd. All rights reserved.