Oxidative dissolution and anion-assisted solubilisation in the transpassive state of nickel-chromium alloys

Iva Betova, Martin Bojinov (Corresponding Author), Tzvety Tzvetkoff

Research output: Contribution to journalArticleScientificpeer-review

19 Citations (Scopus)

Abstract

The transpassive state of pure Ni, Cr and two Ni–Cr alloys (10 and 20 wt.% Cr) in 14.8 M H3PO4 is studied by voltammetric, rotating ring-disc electrode and impedance spectroscopic measurements. The results indicate that the rate of transpassive dissolution of the alloys in a major part of the transpassive range is higher than the rate of this process for both pure metals. A kinetic model retaining the essential features of the corresponding models for the pure metals proposed in the literature has been found to reproduce both the steady-state current versus potential curves and the ac impedance spectra in the transpassive range. The parameters of the model are determined by a fitting procedure and the relevance of their values for the relative importance of two possible pathways in the transpassive state—oxidative dissolution and anion-assisted solubilisation—are discussed.

Original languageEnglish
Pages (from-to)2295-2306
JournalElectrochimica Acta
Volume49
Issue number14
DOIs
Publication statusPublished - 2004
MoE publication typeA1 Journal article-refereed

Keywords

  • nickel-chromium alloys
  • transpassive dissolution
  • surface reactions
  • impedance spectroscopy
  • kinetic model

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