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4643 |
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Tuesday, May 10, 2016, Auditorium 3:55 PM Young Professionals Session |
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TGO formation and failure mode of TBC systems comprising PVD-AlOx interlayers |
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Ibrahim Ali* / Chemnitz University of Technology, Germany Daniel Wett / Institute of composite materials, Technische Universität Chemnitz, Germany Thomas Grund/ Institute of surface technology/functional materials, Technische Universität Chemnitz., Germany Daisy Nestler/ Institute of composite materials, Technische Universität Chemnitz, Germany Guntram Wagner/ Institute of composite materials, Technische Universität Chemnitz, Germany Thomas Lampke/ Institute of surface technology/functional materials, Technische Universität Chemnitz., Germany |
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The physical characteristics and volume growth of TGOs in TBC systems lead to a premature TBC failure. The formation and growth of TGO layers were studied with respect to the modification of the bond coat by adding several elements, pre-oxidation, pre-diffusion oxidation and adding inter-layers at the bond coat/ceramic interface. It is proved that enriching the BC/TC interface with ±-Al2O3 is beneficial to an extended operational time by prolonging the steady-state growth stage of the TGO. The corresponding phase reactions in TBC systems with increased Alumina activity at the interface, however, are not studied yet. In this work the stage formation of TGO layers of TBC systems with PVD-AlOx interlayers is described. The study uses thermal cyclic loading with dwell time at a maximum temperature of 1,150 °C. The crack formation in the ceramic top coat and the TGOs thickness are investigated by means of SEM/EDS after 1, 6, 12, 24, 40 and 80 thermal cycles. The results plot the interface change and crack formation as a function of the thermal cycle number. The corresponding failure mode is discussed. |