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Asian Journal of Scientific Research

Year: 2008 | Volume: 1 | Issue: 2 | Page No.: 113-121
Research Article

The Influence of Media Concentrations on the Passivation Layer Characteristics of Al-Zn Alloys in Brine Environment

C.E. Ekuma
Department of Industrial Physics, P.M.B. 053, Abakaliki, Ebonyi, Nigeria
N.E. Idenyi
Department of Industrial Physics, P.M.B. 053, Abakaliki, Ebonyi, Nigeria
F.K. Onwu
Department of Industrial Chemistry, Ebonyi State University, P.M.B. 053, Abakaliki, Ebonyi, Nigeria
A.E. Umahi
Department of Industrial Physics, P.M.B. 053, Abakaliki, Ebonyi, Nigeria
Corrosion tests were carried out on locally processed aluminum-based alloys with varying weight percentages of zinc. Test coupons of dimensions 17x16.8x15 mm were machined from the as-cast alloy to an average surface area of 1271 mm2. The coupons were immersed in 0.1, 0.25, 0.5 and 1.0 M NaCl solutions with a coupon withdrawn simultaneously from each medium at 24 hourly rate for characterization. The results revealed that the coupons gained weight in all the media indicating the phenomenon of passivation; with the greatest layer thickness observed in the range 0.25 to 0.5 M brine. This behavior is attributed to the increasing electrical conductivity of the solutions; a consequence of increasing solubility of the media which progressively increased peaking within this range and hence, increased passivation kinetics before declining due to the immobility of current carrying ions.
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References

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