Morphology and composition of Ni-Co electrodeposited powders

Abstract

The morphology, phase and chemical composition of Ni-Co alloy powders electrodeposited from an ammonium sulfate-boric acid containing electrolyte with different ratio of Ni/Co ions were investigated. The ratios of NVCo ions were 1/1, 1/2 and 1/3. The morphology, chemical composition and phase composition of the electrodeposited alloy powders were investigated using AES, SEM, EDS and XRD analysis. Composition of the electrolyte, i.e. the ratio of Ni/Co concentrations was found to influence both, the alloy phase composition and the morphology of Ni-Co alloy powders. At the highest ratio of Ni/Co = 1/1 concentrations typical 2D fern-like dendritic particles were obtained. With a decrease of NVCo ions ratio among 2D fern-like dendrites, 3D dendrites and different agglomerates were obtained. X-ray diffraction studies showed that the alloy powders mainly consisted of the face-centered cubic alpha-nickel phase and hexagonal close-packed alpha-cobalt phase and minor proportions of face-centered cubic alpha-cobalt phase. The occurrence of the latter phase was observed only in the alloy powder with the higher cobalt concentration in electrolyte. The electrodeposition of Ni-Co powders occurred in an anomalous manner.