Corrosion mechanisms and products of copper in aqueous solutions at various pH values
- National Univ. of Singapore (Singapore)
The corrosion behavior of copper in aqueous solutions of different pH values was investigated using electrochemical and surface analysis methods. It was shown that the corrosion mechanism changed with pH and was associated with morphology of the surface films formed. In solution of pH 3, the copper surface was covered with porous corrosion products of cuprous oxide (Cu{sub 2}O). Corrosion was controlled predominantly by diffusion in solution. In solutions of pH 4 to pH 5, formation of cubic Cu{sub 2}O on the copper surface provided a diffusion barrier to copper dissolution. The anodic process was controlled by a mixed diffusion of copper ions in oxide films and in solution. In solutions of pH 6 to pH 9, the oxide films (Cu{sub 2}O) became more protective. Diffusion in the oxide films became a rate-determining step of anodic dissolution. In pH 10 solution, a thin, compact Cu{sub 2}O film formed, and spontaneous passivation was observed. At pH 12 and pH 13, analysis by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) demonstrated that the copper surface was covered mainly with a protective monoclinic cupric oxide (CuO) layer. Alternating current impedance measurement results suggested the corrosion process possibly was controlled by diffusion in the oxide films.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 495438
- Journal Information:
- Corrosion, Vol. 53, Issue 5; Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
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