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International Journal of Corrosion
Volume 2013, Article ID 453835, 9 pages
http://dx.doi.org/10.1155/2013/453835
Research Article

Electrochemical and Oxidation Behavior of Yttria Stabilized Zirconia Coating on Zircaloy-4 Synthesized via Sol-Gel Process

1Department of Technical Inspection Engineering, Petroleum University of Technology (PUT), Abadan Institute of Technology (AIT), P.O. Box 619, Abadan 6318714331, Iran
2Department of Material Science Engineering, Isfahan University of Technology (IUT), Isfahan 8415683111, Iran

Received 24 April 2013; Revised 23 November 2013; Accepted 25 November 2013

Academic Editor: W. Ke

Copyright © 2013 S. Rezaee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Sol-gel 8 wt.% Yttria Stabilized Zirconia (YSZ) thin films were prepared on zirconium (zircaloy-4 alloy) by dip-coating technique followed by heat treating at various temperatures (200°C, 400°C, and 700°C) in order to improve both electrochemical corrosion and high temperature oxidation properties of the substrate. Differential thermal analysis and thermogravimetric analysis (DTA-TG) revealed the coating formation process. X-ray diffraction (XRD) was used to determine the crystalline phase structure transformation. The morphological characterization of the coatings was carried out using scanning electron microscopy (SEM). The electrochemical behavior of the coated and uncoated samples was investigated by means of open circuit potential, Tafel, and electrochemical impedance spectroscopy (EIS) in a 3.5 wt.% NaCl solution. The homogeneity and surface appearance of coatings produced was affected by the heat treatment temperature. According to the corrosion parameters, the YSZ coatings showed a considerable increase in the corrosion resistance, especially at higher heat treatment temperatures. The coating with the best quality, from the surface and corrosion point of view, was subjected to oxidation test in air at 800°C. The coated sample presented a 25% reduction in oxidation rate in comparison with bare substrate.