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Synthesis and characterization of yttrium and ytterbium silicates from their oxides and an oligosilazane by the PDC route for coating applications to protect Si3N4 in hot gas environments

Lenz Leite, Mateus and Barroso, Gilvan and Parchovianský, Milan and Galusek, Dušan and Ionescu, Emanuel and Krenkel, Walter and Motz, Günter (2017):
Synthesis and characterization of yttrium and ytterbium silicates from their oxides and an oligosilazane by the PDC route for coating applications to protect Si3N4 in hot gas environments.
In: Journal of the European Ceramic Society, Elsevier Science Publishing, pp. 5177-5191, 37, (16), ISSN 09552219,
DOI: 10.1016/j.jeurceramsoc.2017.04.034,
[Online-Edition: https://doi.org/10.1016/j.jeurceramsoc.2017.04.034],
[Article]

Abstract

Environmental barrier coatings are required to protect Si3N4 against hot gas corrosion and enable its application in gas turbines, among which yttrium and ytterbium silicate-coatings stand out. Thus, the polymer-derived ceramic route was used to synthesize these silicates for basic investigations regarding their intrinsic properties from a mixture of Y2O3 or Yb2O3 powders and the oligosilazane Durazane 1800. After pyrolysis above 1200 °C in air, the silicates are predominant phases. The corrosion behaviour of the resulting composites was tested at 1400 °C for 80 h in moist environments. The material containing x2-Yb2SiO5 and Yb2Si2O7 undergoes the lowest corrosion rate (−1.8 μg cm−2 h−1). Finally, the processing of Y2O3/Durazane 1800 as well-adherent, crack-free and thick (40 μm) coatings for Si3N4 was achieved after pyrolysis at 1400 °C in air. The coating consisted of an Y2O3/Y2SiO5 top-layer and an Y2O3/Y2Si2O7 interlayer due to the interaction of the coating system with the substrate.

Item Type: Article
Erschienen: 2017
Creators: Lenz Leite, Mateus and Barroso, Gilvan and Parchovianský, Milan and Galusek, Dušan and Ionescu, Emanuel and Krenkel, Walter and Motz, Günter
Title: Synthesis and characterization of yttrium and ytterbium silicates from their oxides and an oligosilazane by the PDC route for coating applications to protect Si3N4 in hot gas environments
Language: English
Abstract:

Environmental barrier coatings are required to protect Si3N4 against hot gas corrosion and enable its application in gas turbines, among which yttrium and ytterbium silicate-coatings stand out. Thus, the polymer-derived ceramic route was used to synthesize these silicates for basic investigations regarding their intrinsic properties from a mixture of Y2O3 or Yb2O3 powders and the oligosilazane Durazane 1800. After pyrolysis above 1200 °C in air, the silicates are predominant phases. The corrosion behaviour of the resulting composites was tested at 1400 °C for 80 h in moist environments. The material containing x2-Yb2SiO5 and Yb2Si2O7 undergoes the lowest corrosion rate (−1.8 μg cm−2 h−1). Finally, the processing of Y2O3/Durazane 1800 as well-adherent, crack-free and thick (40 μm) coatings for Si3N4 was achieved after pyrolysis at 1400 °C in air. The coating consisted of an Y2O3/Y2SiO5 top-layer and an Y2O3/Y2Si2O7 interlayer due to the interaction of the coating system with the substrate.

Journal or Publication Title: Journal of the European Ceramic Society
Volume: 37
Number: 16
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: Silazane, Rare-earth silicates, Polymer-derived ceramic, Environmental barrier coating, Hot gas corrosion
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
Date Deposited: 15 Jan 2018 08:54
DOI: 10.1016/j.jeurceramsoc.2017.04.034
Official URL: https://doi.org/10.1016/j.jeurceramsoc.2017.04.034
Funders: The authors acknowledge the Alexander von Humboldt Foundation (AvH) within the Research Group Linkage Programme for the financial support that enabled the exchange of students between the University Bayreuth and the Alexander Dubček University Trenčin.
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