Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Electrical Engineering, Measurement and Control Technology
Abstract An examination has been made of the effect of the composition, pH and the temperature of the solution on the deposition of nickel on iron in a fluidized bed that contained iron powder, solution and a fluidizing gas. In certain cases an electric potential was applied to electrodes contained within the bed, but otherwise the deposition process was spontaneous. Three different solutions were studied: nickel chloride, Watt's solution and nickel sulphamate. In the electroless case the highest and lowest deposition rates obtained under a specific set of experimental conditions were associated with the nickel chloride and nickel sulphamate solutions respectively. Even when an electric current was passed through the bed the spontaneous reactions dominated the process. The optimum pH was about 3.6; at other pH values the deposition of nickel was affected adversely by competitive cathodic reactions. The activation energies suggested that the deposition of nickel on iron powder was charge transfer controlled at temperatures below 60° C, but mixed diffusion and charge transfer control were operative at higher temperatures. The morphology of the coating was independent of the experimental conditions used, and always consisted of a nodular deposit giving incomplete coverage of the particles.
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