Microstructural degradation of Electron Beam-Physical Vapour Deposition Thermal Barrier Coating during thermal cycling tracked by X-ray micro-computed tomography

What is it about?

The degradation of an Electron Beam-Physical Vapour Deposition Thermal Barrier Coating caused by thermal cycling at 1150 degrees C has been followed in 3D non-destructively by time-lapse X-ray micro-computed tomography (mu-CT). Quantitative analysis of X-ray mu-CT virtual cross-sections on small samples is validated by destructive crosssectional scanning electron microscopy (SEM) micrographs of larger ones. The evolution of thermally-grown oxide (TGO) is quantified. The TGO/bond coat interface roughness is measured in 3D. No significant rumpling is observed. Undulations are found locally at the interface of the as-deposited sample. Such undulations can increase in amplitude during cycling providing locations for interfacial cracks to initiate. (C) 2018 Published by Elsevier Ltd on behalf of Acta Materialia Inc.

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