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The use of synchrotron x-ray micro computed tomography to study the failure mechanisms of thermal barrier coatings

Khoshkhou, Danial (2017)
Eng.D. thesis, University of Birmingham.

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Thermal barrier coatings (TBCs) are used to protect high-pressure stage 1 turbine components in aero engines. At present the full potential high-temperature capabilities of TBCs cannot be utilised due to the difficulties in estimating the remaining useful life of in-service TBCs. State of the art non-destructive techniques, such as photo-luminescent piezospectroscopy (PLPS) have aided in furthering the understanding of damage evolution mechanism techniques, but are limited in applicability at temperature. In this work, a new force-balance model is presented for calculating the growth stress in a thermally grown oxide (TGO) layer at oxidation temperatures. Furthermore, a new experimental technique is explored for observation of the full-field strain distribution using synchrotron X-ray microtomography (SX μCT) coupled with digital volume correlation (DVC). The forcebalance method relates the creep in bondcoats of precision-machined cylindrical micro-specimens to the stress acted on the bondcoat by the TGO. These precisionmachined specimens were volumetrically imaged at the I12 JEEP beamline of Diamond Light Source (DLS) to reveal the three-dimensional evolution of TBC microstructure with time at temperature. The time-dependent volumetric image data acquired at DLS were processed using commercial digital volume correlation code to compute full-field displacement and strain distribution.

Type of Work:Eng.D. thesis.
Supervisor(s):Connolly, Brian J. and Evans, Hugh
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Metallurgy and Materials
Additional Information:

Publications resulting from research:

D. Khoshkhou, M. Mostafavi, C. Reinhard, M. P. Taylor, D. S. Rickerby, I. M. Edmonds, H. E. Evans, T. J. Marrow, B. J. Connolly, “Three-dimensional displacement mapping of diffused Pt thermal barrier coatings via synchrotron Xray computed tomography and digital volume correlation” Scripta Materialia, vol. 115, 1 April 2016, pp. 100–103.

S. Zhao, Z. C. Yang, X. G. Zhou, X. Z. Ling, L. S. Mora, D. Khoshkhou, and T. J. Marrow, “Design, Fabrication, Characterization and Simulation of PIP-SiC/SiC Composites,” Computers, Materials and Continua, vol. 42, no. 2, pp. 103–124, 2014.

L. S. Mora, M. Mostafavi, D. Khoshkhou, C. Reinhard, R. Atwood, S. Zhao, B. J. Connolly, T. J. Marrow, and Z. Shuang, “3D cellular automata finite element (CAFE) modelling and experimental observation of damage in quasi-brittle nuclear materials: Indentation of a SiC-SiC fibre ceramic matrix composite,” in Third International Workshop on Structural Materials for Innovative Nuclear Systems (SMINS-3), 2013, pp. 241–250.

Subjects:TL Motor vehicles. Aeronautics. Astronautics
TN Mining engineering. Metallurgy
Institution:University of Birmingham
ID Code:7817
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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