Formation of dual diffusion layer by pulsing currents

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10 Citations (Scopus)

Abstract

Electrodeposition by pulse currents is often used to obtain fine grained coatings. During such a process, a high current pulse, in the order of milliseconds, causes a depletion layer to be formed in the immediate vicinity of the electrode. Thereafter, the current is switched off and the metal ion concentration is replenished by convective diffusion toward the electrode surface. As a result, a dual boundary layer is formed: (1) an inner one, in the immediate vicinity of the electrode which is sensitive to current pulsations and thereby unsteady-state parameters and, (2) an outer one, which resembles a steady state mass transfer boundary layer. The approach toward unsteady-state diffusion limitations is described by N p, which is the ratio between the pulse peak current and pulse limiting current. The distance from steady state limitations is quantified by N m, the ratio of the average plating current to the steady state diffusion limiting current. The usefulness of using these engineering parameters to obtain deposits with desirable properties is discussed.

Original languageEnglish
Pages (from-to)1756-1760
Number of pages5
JournalIndustrial and Engineering Chemistry Research
Volume51
Issue number4
DOIs
Publication statusPublished - 1 Feb 2012

Keywords

  • deposition
  • diffusion
  • electrodes
  • layers
  • mass transfer

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