Impedance study of Ni–Co electro-deposition on Fe powder particles in fluidised bed systems |
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Authors: | Renáta Oriňáková Hans-Dieter Wiemhöfer Jürgen Paulsdorf Veronika Barinková Anna Bednáriková Roger M Smith |
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Institution: | (1) Institute of Chemistry, P.J. Šafárik University, 04101 Košice, Slovak Republic;(2) Institute of Inorganic and Analytical Chemistry, University of Münster, 48149 Münster, Germany;(3) Department of Chemistry, Loughborough University, LE11 3TU Loughborough, UK |
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Abstract: | The electrochemical impedance method was applied during the electrochemical deposition of a binary Ni–Co coating on iron powder in a fluidised bed electrode system. The influence of the suspension density on the charge transfer in the course of the electro-deposition process was studied. At a potential of −900 mV (vs. Ag/AgCl/3 M KCl), when the binary Ni–Co layer was formed, the impedance data were characterised by two semicircles with the semicircle at high frequencies being larger in magnitude. A contribution of the diffusion process to the overall current was observed. The optimal suspension density for the charge transfer in the bed was 10×10−3–15×10−3 (i.e., 4–6 g of iron powder in 50 ml of electrolyte). The most probable mechanism of the charge transfer for the studied concentrations of powder particles is the convective mechanism. The iron particles dispersed in the electrolyte were considered to act as either a depolariser or an additional working electrode depending on the applied electrode potential and on the suspension density. |
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Keywords: | ElS Electro-deposition Ni– Co Charge transfer Fluidised bed electrode Iron microparticles |
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