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The Improved Passivation of Aluminum and Structure of Amorphous Alumina Formed on Aluminum During Oxidation in Various Environments

Published online by Cambridge University Press:  02 July 2020

G. -W . Zhou
Affiliation:
Materials Science & Engineering Department, University of Pittsburgh, Pittsburgh, PA15261
A. Kuznetsova
Affiliation:
Dept. of Chemistry, University of Pittsburgh, Pittsburgh, PA15261
M. D. Bhardwaj
Affiliation:
Materials Science & Engineering Department, University of Pittsburgh, Pittsburgh, PA15261
J. T. Yates
Affiliation:
Dept. of Chemistry, University of Pittsburgh, Pittsburgh, PA15261
J. C Yang
Affiliation:
Materials Science & Engineering Department, University of Pittsburgh, Pittsburgh, PA15261
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Extract

Nearly all metals form a passivation film due to oxidation in air at ambient temperatures, that acts as a diffusion barrier to protect the materials from further corrosion. Aluminum demonstrates excellent passivation behavior due to the formation of a protective amorphous alumina film during exposure to air at ambient temperatures. However, H. Ebinger and J. Yates discovered that the passivation of aluminum can be significantly improved by artificial oxidation. Both electron-beam induced oxidation in water vapor and oxidation in ozone atmospheres3 showed higher impedance in electrochemical impedance spectroscopy measurements to anion diffusion than the thermally grown oxides. To understand the nature of this beneficial passivation, we probed the microstructure of these amorphous oxide films by transmission electron microscopy (TEM).

The oxide films were grown on a polycrystalline Al substrate. The Al substrate was cleaned with a sputter cleaner inside a UHV (ultra-high vacuum) system.

Type
Sir John Meurig Thomas Symposium: Microscopy and Microanalysis in the Chemical Sciences
Copyright
Copyright © Microscopy Society of America

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References

1.Ebinger, H. and Yates, J. T., Phy. Rev. B, 57(3), (1988), 1976.CrossRefGoogle Scholar
2.Kuznetsova, A., Burleigh, T., Zhukov, V., Blachere, J. and Yates, J., Langmuir, 14, (1998) 502.CrossRefGoogle Scholar
3.Kuznetsova, A.,. Zhou, G. -W., Yang, J. C. and Yates, J. T., in preparation.Google Scholar