Characterization of rare-earth conversion films formed on the AZ31 magnesium alloy and its relation with corrosion protection

Two pre-treatments were studied for AZ31 Mg alloy substrates, consisting of immersion in cerium nitrate and lanthanum nitrate solutions for various immersion times. The surface composition was investigated by X-ray photoelectron spectroscopy and Auger electron spectroscopy that revealed the presence...

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Bibliographic Details
Published in:Applied surface science 2007-06, Vol.253 (16), p.6922-6931
Main Authors: MONTEMOR, M. F, SIMOES, A. M, CARMEZIM, M. J
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Physics
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Summary:Two pre-treatments were studied for AZ31 Mg alloy substrates, consisting of immersion in cerium nitrate and lanthanum nitrate solutions for various immersion times. The surface composition was investigated by X-ray photoelectron spectroscopy and Auger electron spectroscopy that revealed the presence of a surface film containing the rare-earth cation, with a composition which was time dependent in the case of the cerium pre-treatment. The corrosion behaviour of the pre-treated substrates in 0.005M NaCl solutions was assessed by potentiodynamic polarization, open circuit potential monitoring and the scanning vibrating electrode technique (SVET). The electrochemical results show that the pre-treatments reduced the corrosion activity of the AZ31 Mg alloy substrates in the presence of chloride ions. The corrosion protection efficiency is dependent on the treatment time.
ISSN:0169-4332
1873-5584
DOI:10.1016/j.apsusc.2007.02.019