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Advances in Materials Science and Engineering
Volume 2013, Article ID 790318, 13 pages
http://dx.doi.org/10.1155/2013/790318
Research Article

Evaluation of Normal and Nanolayer Composite Thermal Barrier Coatings in Fused Vanadate-Sulfate Salts at 1000°C

Department of Materials, Manufacturing and Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia

Received 21 May 2013; Accepted 28 July 2013

Academic Editor: Rui Vilar

Copyright © 2013 Mohammadreza Daroonparvar 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

Hot corrosion behavior of yttria stabilized zirconia (YSZ), YSZ/normal Al2O3, and YSZ/nano-Al2O3 coatings was investigated in the presence of molten mixture of Na2SO4 + V2O5 at 1000°C. Microstructural characterization showed that the creation of hot corrosion products containing YVO4 crystals and monoclinic ZrO2 is primarily related to the reaction between NaVO3 and Y2O3 during hot corrosion. The lowest amount of hot corrosion products was observed in YSZ as an inner layer of YSZ/nano-Al2O3 coating. Hence, it can be concluded that the presence of nanostructured Al2O3 layer over the conventional YSZ coating can considerably reduce the infiltration of molten corrosive salts into the YSZ layer during hot corrosion which is mainly related to the compactness of nanostructured alumina layer (including nanoregions) in comparison with normal alumina layer.