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Evaluation of CaO-CeO2-partially stabilized zirconia thermal barrier coatings

Ramaswamy, Parvati and Seetharamu, S and Rao, KJ and Varma, KBR (1999) Evaluation of CaO-CeO2-partially stabilized zirconia thermal barrier coatings. In: Ceramics International, 25 (4). pp. 317-324.

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Abstract

Plasma sprayable powders were prepared from ZrO2-CaO-CeO2 system using an organic binder and coated onto stainless steel substrates previously coated by a bond coat (Ni 22Cr 20Al 1.0Y) using plasma spraying. The coatings exhibited good thermal barrier characteristics and excellent resistance to thermal shock at 1000 degrees C under simulated laboratory conditions (90 half hour cycles without failure) and at 1200 degrees C under accelerated burner rig test conditions (500 2 min cycles without failure). No destabilization of cubic/tetragonal ZrO2 phase fraction occured either during the long hours (45 h cumulative) or the large number of thermal shock tests. Growth of a distinct SiO2 rich region within the ceramic was observed in the specimens thermal shock cycled at 1000 degrees C apart from mild oxidation of the bond coat. The specimens tested at 1200 degrees C had a glassy appearance on the top surface and exhibited severe oxidation of the bond coat at the ceramic-bond coat interface. The glassy appearance of the surface is due to the formation of a liquid silicate layer attributable to the impurity phase present in commercial grade ZrO2 powder. These observations are supported by SEM analysis and quantitative EDAX data.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Elsevier Science.
Keywords: Thermal shock resistance;Thermal barrier coating;Partially stabilized zirconia;Plasma spray.
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 01 May 2009 04:47
Last Modified: 19 Sep 2010 05:27
URI: http://eprints.iisc.ernet.in/id/eprint/19294

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