Electrodeposition and morphology of Ni-Co alloy powders by constant and pulsating overpotential electrolysis

ISSN： 1068-1302

Source： Powder Metallurgy and Metal Ceramics, Vol.49, Iss.11-12, 2011-03, pp. : 707-715

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Abstract

The polarization dependences are recorded and the conditions of Ni-Co powder formation in amino-chloride electrolyte are found for different proportions of Ni²⁺/Co²⁺. Energy-dispersive spectral analysis (EDSA) is used to obtain data on the morphology and elemental composition of Ni-Co alloy powders depending on the Ni²⁺ and Co²⁺ ratio in the solution and the type and parameters of applied (controlled potential) current mode (stationary and impulse). It is found out that the increase of the Ni²⁺/Co²⁺ ratio in the solution results in the formation of finer powders as well as in higher nickel content of the powder, up to 64%. The application of impulse mode strongly increases both the dispersion (average size of the particles about 3-5 μm) and the powder homogeneity, which leads to lower oxide content of Ni-Co powders (below 2%). The increase in the impulse frequency to 1000 Hz, other conditions being equal, decreases the formation of dendrites and the susceptibility of powder particles to agglomeration.