10270 Corrosion Behavior of Al-An Coatings in 5% wt NACL Solution

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Product Number: 51300-10270-SG

ISBN: 10270 2010 CP

Author: Andrea Perez, Alain Billard, Sebastien Touzain and Juan Creus

Publication Date: 2010

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Several aluminum-based coatings deposited by magnetron sputtering Physical Vapor Deposition were tested as an alternative solution to chromium, nickel and zinc-based coatings in order to protect efficiently steel from corrosion. The objective of this study is to define the corrosion parameters of different Al-Zn compositions with a zinc content varying from 3 at.% to 19 at.% and to study the behavior of interesting compositions during an immersion test in NaCl 5 wt.% solution.

The results show that the corrosion behavior depends on the zinc content. Below a specific value of zinc content, in the range between 10 at.% and 16 at.%, the alloys suffer from pitting corrosion. Above 16 at.% Zn, the corrosion is uniform. Besides, the reactivity increases with zinc content while the open circuit potential shifts toward more negative values and gets closer to the pure zinc open circuit potential in this medium. For the samples showing a uniform corrosion, the immersion test reveals that they provide a good protection to steel during the immersion period.

These alloys present very interesting properties for steel protection, when the zinc content is high enough to have uniform corrosion. Nevertheless, the zinc content has to be well defined in order to avoid a high dissolution of the coating.

Keywords : Corrosion, Al-Zn, magnetron sputtering, sacrificial coatings