Authors: Fanny Riallant Jonathan Cormier Arnaud Longuet Xavier Milhet José Mendez
Publish Date: 2013/08/30
Volume: 45, Issue: 1, Pages: 351-360
Abstract
The failure mechanisms of a NiAlPt/electron beam physical vapor deposition yttriastabilizedzirconia thermal barrier coating system deposited on the AM1 single crystalline substrate have been investigated under pure creep conditions in the temperature range from 1273 K to 1373 K 1000 °C to 1100 °C and for durations up to 1000 hours Doubly tapered specimens were used allowing for the analysis of different stress states and different accumulated viscoplastic strains for a given creep condition Under such experiments two kinds of damage mechanisms were observed Under low applied stress conditions ie long creep tests microcracking is localized in the vicinity of the thermally grown oxide TGO Under high applied stress conditions an unconventional failure mechanism at the substrate/bond coat interface is observed because of large creep strains and fast creep deformation hence leading to a limited TGO growth This unconventional failure mechanism is observed although the interfacial bond coat/top coat TGO thickening is accelerated by the mechanical applied stress beyond a given stress thresholdThe authors are grateful to SnecmaSAFRAN group for the FR PhD Grant for sponsoring the current study and for providing the samples The authors thank Florence Hamon and Florent Mauget Engineers in the Physics and Mechanics of Materials Department at the Pprime Institute for their help and for fruitful discussions in conducting several experiments The current study is conducted under the French program “PRC Structures Chaudes’’ involving SnecmaSAFRAN group TurbomecaSAFRAN group ONERA CEATDGA and CNRS Laboratories Mines Paris Tech Institut Pprime–ISAEENSMA LMTCachan and CIRIMATENSIACET Financial support by the French Ministry of Transportation Direction des Programmes de l’Aviation Civile is also gratefully acknowledged
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