Active/passive behavior of copper in strong sulfuric acid

Journal Article · Sun Feb 01 04:00:00 EST 1998 · Journal of the Electrochemical Society

DOI:https://doi.org/10.1149/1.1838310· OSTI ID:599920

Tromans, D; Ahmed, T ^[1]

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1. Univ. of British Columbia, Vancouver, British Columbia (Canada). Dept. of Metals and Materials Engineering

A combination of thermodynamic analyses and potentiodynamic polarization tests have been used to study the anodic behavior of Cu in strong H{sub 2}SO{sub 4} solutions in the concentration range 1--10 M. The studies were supplemented by chemical analyses of surface films. It was found that concentration-dependent changes in the activity of water played a major role in determining the anodic behavior and relative stability of corrosion product films. The anodic Tafel slope decreased from {approximately} 41 to {approximately} 31 mV with increasing acid concentration. The onset of limiting current and active-passive behaviors at higher potentials was determined by the formation of films of hydrated copper sulfate, CuSO{sub 4} {center_dot} xH{sub 2}O, and not by formation of oxides. Limiting current behavior was observed in 1 M solutions, where the degree of hydration was x = 5. Well-developed passivity occurred in 10 M solutions where x = 1. The results are relevant to industrial electrorefining operations for Cu and indicate that chloride contamination, if present in sufficient amounts, could cause the premature onset of limiting current behavior (anode passivity) during refining.

• Sponsoring Organization: USDOE
• OSTI ID: 599920
• Journal Information: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 2 Vol. 145; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COPPER
COPPER SULFATES
CORROSION PRODUCTS
ELECTROCHEMICAL CORROSION
ELECTROREFINING
PASSIVATION
PROTECTIVE COATINGS
SULFURIC ACID