Interface fracture toughness in thermal barrier coatings by cross-sectional indentation

Wang, Xin, Wang, Changjiang and Atkinson, Alan (2012) Interface fracture toughness in thermal barrier coatings by cross-sectional indentation. Acta Materialia, 60 (17). pp. 6152-6163. ISSN 1359-6454

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The interface fracture toughness of thermal barrier coatings (TBCs) on high-pressure turbine blades manufactured by electron beam physical vapour deposition was measured by a cross-sectional indentation (CSI) method. Scanning electron microscopy and luminescence mapping were employed to reveal that coating delamination induced by CSI was predominantly along the thermally grown oxide–bond coat interface and the shape of the delaminated area was approximately semicircular. The critical energy release rate (Gc)for delamination was calculated based on a clamped circular plate model. Analysis of the stored energy release revealed that the residual stresses in the coating do not contribute to the total energy release rate provided that the delaminated area of the coating does not buckle. Therefore, for this method, detailed information of residual stresses is not necessary for the determination of interface fracture toughness. However, intercolumnar microfracture and shear displacement in the YSZ top coat can lead to significant overestimation of the interface fracture toughness in some situations. A method of specimen preparation is described to inhibit these effects. The interface fracture resistance of the TBCs was found to be 29 ± 9 J/m−2 after between 35 and 100 thermal cycles (from room temperature to 1150 °C with 1 h duration.

Item Type: Article
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Subjects: T Technology > TA Engineering (General). Civil engineering (General) > TA0401 Materials of engineering and construction. Mechanics of materials
Depositing User: Chang Wang
Date Deposited: 11 Sep 2013 06:28
Last Modified: 11 Sep 2013 07:09
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