7. Determination of the Fracture Toughness of Thermally Grown Oxide (TGO) in a Thermal Barrier System

  1. Dongming Zhu and
  2. Kevin Plucknett
  1. Jürgen Malzbender1,
  2. Isabel Escobar1,
  3. Roland Herzog1,
  4. Rolf W. Steinbrech1 and
  5. Heinrich Öttel2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291238.ch7

Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3

Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3

How to Cite

Malzbender, J., Escobar, I., Herzog, R., Steinbrech, R. W. and Öttel, H. (2005) 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

Author Information

  1. 1

    Forschungszentrum Jülich GmbH Institute for Materials and Processes in Energy Systems 52428 Jülich, Germany

  2. 2

    Freiberg University of Mining and Technology Institute for Physical Metallurgy 9596 Freiberg, Germany

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2005

ISBN Information

Print ISBN: 9781574982336

Online ISBN: 9780470291238

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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.