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|Title:||Effect of oxygen and oxidizers on the electrochemical behaviour of a-brass in aqueous solutions of different pH|
|Authors:||AI-Kharafi, F M|
Badawy, W A
|Abstract:||The electrochemical behaviour of a-brass (Cu:Zn ≈ 70:30) in naturally aerated, oxygen saturated and oxygen free acidic, neutral and basic solutions of constant pH has been investigated. The effect of oxygen and oxidizers on the corrosion behaviour of the alloy in the different solutions has been discussed. The effect of oxygen or oxidizers on the corrosion parameters of the alloy is dependent on the solution pH. The removal of oxygen or oxidizers from acidic solutions increases the corrosion resistance of the alloy. In these solutions, the presence of oxygen or oxidizers enhances disproportionation reactions which lead to the breakdown of the passive film formed on the alloy surface. The preferential dissolution of zinc has been found to destroy the passive film, especially in acidic solutions. X-ray photoelectron spectroscopic investigations (XPS) of the alloy surface after long immersion time in solutions containing Cr2O ions have shown that chromium is not incorporated in the barrier film. Scanning electron microscopy (SEM) does not show remarkable difference between the polished surface and the surface after immersion in the test solutions. In-acidic solutions containing dichromate ions increased corrosion rates have been measured and clear corrosion patterns in the scanning electron micrographs have been recorded.|
|ISSN:||0975-0991 (Online); 0971-457X (Print)|
|Appears in Collections:||IJCT Vol.05(1) [January 1998]|
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