Etude des mécanismes d'endommagement d'un système barrière thermique déposé sur un superalliage base nickel

Abstract : Thermal barrier coatings (TBC) deposited on nickel superalloy are developed for high-pressure turbine of turbofan.TBC is a duplex coating composed of a ceramic top-coat designed for thermal insulation and an intermetallic compound which accommodate the difference of the thermal expansion coefficient between the superalloy and the the ceramic top-coat. The oxidation of the intermetallic compound lead to the formation of a protective alumina scale which prevent oxidation of the superalloy.This study enabled to improve the understanding of the damage mechanism of TBC systems for complex loadings close to in-service loadings. For this purpose, isothermal and cyclic oxidation tests but also thermomechanical fatigue were performed. Tests were stopped before spalling of the TBC in order to study damage mechanisms and, for some of them, kinetics of damage. Some of these tests were followed by compression tests in order to measure the residual spalling resistance, which is responsible of the life duration of the turbines.Thanks to the use of observations from the macroscopic scale to the transmission electron microscope scale, damage mechanisms as well as their consequences on the residual spalling resistance were discussed according to the loadings conditions (isothermal or cyclic with or without mechanical loadings) and according to the sulphur level in the superalloy
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https://pastel.archives-ouvertes.fr/pastel-00936161
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Submitted on : Friday, January 24, 2014 - 3:42:25 PM
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  • HAL Id : pastel-00936161, version 1

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Catherine Guerre. Etude des mécanismes d'endommagement d'un système barrière thermique déposé sur un superalliage base nickel. Sciences de l'ingénieur [physics]. École Nationale Supérieure des Mines de Paris, 2002. Français. ⟨pastel-00936161⟩

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