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Thermal barrier coating by electron beam-physical vapor deposition of zirconia co-doped with yttria and niobia

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Author(s): Daniel Soares de Almeida | Carlos Alberto Alves Cairo | Cosme Roberto M. Silva | Maria do Carmo A. Nono

Journal: Journal of Aerospace Technology and Management
ISSN 1984-9648

Volume: 2;
Issue: 2;
Start page: 195;
Date: 2010;
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Keywords: TBC | EB-PVD | Zirconia | Niobia | Thermal conductivity

ABSTRACT
The most usual ceramic material for coating turbine blades is yttria doped zirconia. Addition of niobia, as a co-dopant in the Y2O3-ZrO2 system, can reduce the thermal conductivity and improve mechanical properties of the coating. The purpose of this work was to evaluate the influence of the addition of niobia on the microstructure and thermal properties of the ceramic coatings. SEM on coatings fractured cross-section shows a columnar structure and the results of XRD show only zirconia tetragonal phase in the ceramic coating for the chemical composition range studied. As the difference NbO2,5-YO1,5 mol percent increases, the tetragonality increases. A significant reduction of the thermal conductivity, measured by laser flash technique in the zirconia coating co-doped with yttria and niobia when compared with zirconia-yttria coating was observed.
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