Journals Information
Universal Journal of Chemistry(CEASE PUBLICATION) Vol. 1(2), pp. 11 - 20
DOI: 10.13189/ujc.2013.010201
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Electrochemical Behavior of Cu-Ag Alloys in Perchlorate Solutions Using Cyclic Voltammetric and Current Transients Techniques
A. M. Zaky1,2,*, M. A. Al-Khaldi2
1 Chemistry Department, College of Sciences, University of Dammam., PB 838, Dammam 31113, Saudi Arabia
2 Chemistry Department, Faculty of Sciences, South Valley University, Qena 83523, Egypt
ABSTRACT
The electrochemical behavior of Cu-Ag system was studied in 0.5 M NaOH and sodium perchlorate by means of cyclic voltammetry, potentiodynamic anodic polarization and current/ time transients techniques. SEM and EDX microanalysis were used to examine the changes caused by the electrochemical perturbations. In perchlorate free alkali solution the anodic portion of the voltammogram was characterized by the existence of two potential regions I and II. In the first potential region copper dissolves preferentially and exhibits three anodic peaks A1, A2 and A3. The anodic peak A1 was related to the formation of Cu2O while the anodic peaks A2 and A3 are related to the oxidation of Cu and Cu2O, respectively to CuO and Cu(OH)2. The preferential dissolution of copper was enhanced and the simultaneous dissolution of silver was retarded on increasing the silver content in the alloy. The potential region II was characterized by the appearance of three anodic peaks A4, A5 and A6 which are related o the formation of mono-layer, and multi-layers of Ag2O, AgO and Ag2O3, respectively. The addition of increasing amounts of ClO4- increases the heights of the anodic peaks and above a limiting value breakdown the anodic passivity and initiate pitting corrosion. The pitting potential decreases linearly with ClO4- concentration but increases with increasing scan rate. The potentiostatic current time transients show that the pitting corrosion can be described in terms of an instantaneous three dimensional grows under diffusion control. X-ray diffraction analysis was used to determine the composition of the corrosion products on the electrode surface. Scanning electron microscope was used to monitor pitting corrosion and to elucidate the effect of constituents on the alloy dissolution.
KEYWORDS
Cu-Ag alloys, perchlorate, pitting corrosion, cyclic voltammetry, Current-time transients, SEM and x-ray diffraction
Cite This Paper in IEEE or APA Citation Styles
(a). IEEE Format:
[1] A. M. Zaky , M. A. Al-Khaldi , "Electrochemical Behavior of Cu-Ag Alloys in Perchlorate Solutions Using Cyclic Voltammetric and Current Transients Techniques," Universal Journal of Chemistry(CEASE PUBLICATION), Vol. 1, No. 2, pp. 11 - 20, 2013. DOI: 10.13189/ujc.2013.010201.
(b). APA Format:
A. M. Zaky , M. A. Al-Khaldi (2013). Electrochemical Behavior of Cu-Ag Alloys in Perchlorate Solutions Using Cyclic Voltammetric and Current Transients Techniques. Universal Journal of Chemistry(CEASE PUBLICATION), 1(2), 11 - 20. DOI: 10.13189/ujc.2013.010201.