Electrolytic Production of Nickel-Cobalt Magnetic Alloys from Solid Oxides in Molten Carbonates

Nickel-cobalt (Ni–Co) alloy was prepared by electrochemical reduction of solid NiO and Co3O4 powder in molten Na2CO3-K2CO3 melt at 750°C. Cyclic voltammetry (CV) and potentiostatic electrolysis experiments indicate that the electroreduction experiences an initial rapid reduction of Co3O4 to CoO, followed by a further co-reduction of NiO and CoO to Ni-Co alloy. The metallic Ni-Co powder was obtained either by potentiostatic electrolysis at potential more negative than −1.25 V (vs. Ag/Ag2SO4) or by constant cell voltage electrolysis at above 1.7 V. An oxide-layer-covered Ni11Fe10Cu alloy rod serving as an inert anode for oxygen evolution behaved stably and reliably for long-term operation. Ni and Co distributed uniformly in the product. The morphology and crystal phase of the alloy was significantly influenced by the electrolysis time. Furthermore, the obtained Ni-Co powders were typical ferromagnetic alloy with relatively high saturation magnetization.