Chapter 7. Determination of the Fracture Toughness of Thermally Grown Oxide (TGO) in a Thermal Barrier System
- Dongming Zhu,
- Kevin Plucknett
Published Online: 26 MAR 2008
DOI: 10.1002/9780470291238.ch7
Copyright © 2005 The American Ceramics Society
Book Title
Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3
Additional Information
How to Cite
Malzbender, J., Escobar, I., Herzog, R., Steinbrech, R. W. and Öttel, H. (2008) Determination of the Fracture Toughness of Thermally Grown Oxide (TGO) in a Thermal Barrier System, in Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3 (eds D. Zhu and K. Plucknett), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291238.ch7
Publication History
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 2005
Book Series:
ISBN Information
Print ISBN: 9781574982336
Online ISBN: 9780470291238
- Summary
- Chapter
- References
Keywords:
- alumina;
- zirconia;
- heterogeneous;
- geometry;
- micrographs
Summary
Stiffness and fracture toughness of thermally grown oxide (TGO) scales were determined using depth sensing micro-indentation. Cross-section specimens of plasma sprayed thermal barrier composites with TGO of different thickness (3-10 μm) were tested applying a Vickers indenter at loads between 50 and 1000 mN. The elastic recovery stiffness was measured at different locations of the undulated TGO, obtaining for low loads and valley positions values comparable to bulk alumina. The fracture toughness was derived from indentation crack length. Hardly any cracks could be generated normal to the TGO interfaces, presumably due to the in-plane compressive stress. From the indentation cracks parallel to the interfaces a fracture toughness of ∼ 1 MPa·m1/2 was determined after eliminating the influence of the more compliant bond coat and ceramic top coat adjacent to the TGO.