Perchlorate Pitting Corrosion of a Passivated Silver Electrode
Ibrahim, Magdy; Mohammed A. Amin; Sayed S. Abd El Rehim; Hamdy H. Hassan;
Abstract
The passivation and pitting breakdown of a silver electrode in sodium hydroxide solutions containing sodium perchlorate was studied using potentiodynamic and potentiostatic
techniques. In perchlorate-free alkali solution, the voltammogram exhibits three anodic peaks prior to oxygen evolution. The ®rst two peaks correspond to the oxidation of Ag and formation of a passive ®lm of Ag2O on the electrode surface, the third to the conversion of Ag2O to AgO. In the presence of ClOÿ 4 , the voltammogram depends considerably on perchlorate concentration. ClOÿ4 increases the height of the three anodic peaks, and at potentials above a limiting value breakdown of the anodic passivity and initiation of pitting corrosion occurs. The pitting potential decreases linearly with ClO4 concentration but increases with scan rate. The potentiostatic current/time transients show that pitting corrosion can be described in terms of an instantaneous three dimensional growth under diffusion control.
techniques. In perchlorate-free alkali solution, the voltammogram exhibits three anodic peaks prior to oxygen evolution. The ®rst two peaks correspond to the oxidation of Ag and formation of a passive ®lm of Ag2O on the electrode surface, the third to the conversion of Ag2O to AgO. In the presence of ClOÿ 4 , the voltammogram depends considerably on perchlorate concentration. ClOÿ4 increases the height of the three anodic peaks, and at potentials above a limiting value breakdown of the anodic passivity and initiation of pitting corrosion occurs. The pitting potential decreases linearly with ClO4 concentration but increases with scan rate. The potentiostatic current/time transients show that pitting corrosion can be described in terms of an instantaneous three dimensional growth under diffusion control.
Other data
Title | Perchlorate Pitting Corrosion of a Passivated Silver Electrode | Authors | Ibrahim, Magdy ; Mohammed A. Amin ; Sayed S. Abd El Rehim ; Hamdy H. Hassan | Keywords | Pitting corrosion; Silver anode; Perchlorate anion. | Issue Date | 1999 | Publisher | Springer-Verlag | Journal | Monatshefte fuer Chemie/Chemical Monthly |
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