Abstract No.:
2783

 Title:
Degradation process of RE2Zr2O7 thermal barrier coatings during isothermal annealing

 Authors:
Grzegorz Moskal / Silesian University of Technology, Poland

 Abstract:
A topic of this paper is general characteristics of phenomena, which occur during isothermal annealing of the TBC layers, obtained as a result of spraying by the APS method of zirconate powders on a base of rare earth elements (Gd, La, Sm and Nd). A scope of researches comprised macroscope evaluation of the TBC layers after time duration since 2 up to 500 hours of isothermal annealing in temperature 1100°C. A series of microstructural researches was performed in order to define observed phenomena in details and observation of phenomena in an occurrence zone of the TGO oxides was a basic direction in these researches. Measurements of thickness of oxides in a function of temperature were carried out and a structure of the TGO layers was defined. After 500 hours, two areas, typical for the Al2O3 oxide and for oxides of spinel nature type Ni(Cr)Al2O4, were predominant. A zone of spinels is characterized by presence of numerous fine pores and gaps and micro-cracks, which are parallel to sample surface. Cracks, observed partially, penetrated to a ceramic layer. The EBSD analysis, additionally revealed presence of transitional phases of a perovskite structure e.g. the GdAlO3 phase, what accelerated an effect of degradation, related to a cracking process of a ceramic layer.
Financial support of Structural Funds in the Operational Programme - Innovative Economy (IE OP) financed from the European Regional Development Fund - Project No POIG.0101.02-00-015/09 is gratefully acknowledged.


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