The anodic behaviour of Sb and Pb-Sb eutectic in sulphuric acid solutions

S. Laihonen, Timo Laitinen, Göran Sundholm, Arto Yli-Pentti

Research output: Contribution to journalArticleScientificpeer-review

33 Citations (Scopus)

Abstract

Ring—disc voltammetric experiments on antimony in H2SO4 solutions show that a partly passivating oxide layer is formed on the metal surface preventing oxygen evolution.
Due to the ionic conductivity and/or porosity of the layer the dissolution of the metal proceeds through the layer, and its rate is controlled by diffusion in the layer. Antimony is dissolved mainly in the trivalent state. Based on the determinations of the Tafel coefficient the mechanism of dissolution is dependent on the acid concentration. In the case of the lead—antimony eutectic the formation of a semipermeable lead sulphate membrane retards the rate of dissolution. ac Impedance measurements on antimony show features of a simple passivation process, eg a negative polarization resistance after the maximum in the current.
The effect of mass transfer through the oxide layer is also observed. Thus the ac impedance measurements confirm the interpretation given above.
Original languageEnglish
Pages (from-to)229-238
JournalElectrochimica Acta
Volume35
Issue number1
DOIs
Publication statusPublished - 1990
MoE publication typeA1 Journal article-refereed

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