Corrosion properties of electrodeposited cobalt in sulfate solutions containing chloride ions

Hundal Jung, Akram Alfantazi

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The corrosion properties of electrodeposited pure cobalt were investigated in deaerated 0.5 M Na2SO4 solutions at pH 5, 7, 10 and 13 by using polarization techniques. The effect of chloride concentration (0.01 and 0.1 M NaCl) was also studied. The results showed that increasing pH shifted the anodic polarization curves to more negative potentials. At pH 5 and 7, cobalt exhibited active dissolution without any distinctive transition to passivation. However, at pH 10, the metal surface was partially passivated and anodic current increased sharply at approximately -0.2 VSCE and the corroded surface revealed several well-defined pits. On the other hand, at pH 13, a clear passivation region was observed within the potential range of -0.5 to 0.6 VSCE. With increasing chloride concentrations of 0, 0.01, and 0.1 M at pH 10, both the anodic current and the number of pits on the cobalt surface were gradually increased. X-ray photoelectron spectroscopic investigations showed that the cobalt surface was covered mostly with cobalt hydroxide after anodic polarization at pH 10 in 0.1 M NaCl.

Original languageBritish English
Pages (from-to)865-869
Number of pages5
JournalElectrochimica Acta
Volume55
Issue number3
DOIs
StatePublished - 1 Jan 2010

Keywords

  • Chloride
  • Cobalt
  • Corrosion
  • Pitting
  • X-ray photoelectron spectroscopy

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