ELECTRODEPOSITION AND MORPHOLOGY OF Ni–Co ALLOY POWDERS BY CONSTANT AND PULSATING OVERPOTENTIAL ELECTROLYSIS

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⁺/Со²⁺. 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 the applied (controlled potential) current mode (stationary and impulse). It is found out that the increase of the Ni²⁺/Со²⁺ ratio in the solution results in the formation of finer powders as well as in higher nickel content in the powder up to 64%. The application of impulse mode strongly increases both the dispersion (average size of the particles about 3–5 m) and the powder homogeneity, which leads to lower oxide content in Ni-Co powders (below 2%). The increase of the impulse frequency to 1000 Hz, other conditions being equal, decreases the formation of dendrites and the susceptibility of powder particles to agglomeration.