Time-Economic Lifetime Assessment for High Performance Thermal Barrier Coating Systems |
| Journal |
Key Engineering Materials (Volume 333) |
| Volume |
Functional Gradient Ceramics, and Thermal Barriers |
| Edited by |
Marc Anglada et al. |
| Pages |
147-154 |
| DOI |
10.4028/www.scientific.net/KEM.333.147 |
| Online since |
March, 2007 |
| Authors |
Marion Bartsch,
Bernd Baufeld,
S. Dalkilic,
Iulian Mircea,
K. Lambrinou,
T. Leist,
J. Yan,
Anette M. Karlsson
|
| Keywords |
Accelerated Testing, Damage Parameter, Lifetime Assessment, Thermal Barrier Coating (TBC) |
| Abstract |
Strategies for time-economic lifetime assessment of thermal barrier coatings (TBC) in
service are described and discussed on the basis of experimental results, achieved on material
systems with coatings applied by electron beam physical vapour deposition. Service cycles for gas
turbine blades have been simulated on specimens in thermo-mechanical fatigue tests, accelerating
the fatigue processes by an increase of load frequency. Time dependent changes in the material
system were imposed by a separate ageing, where the samples were pre-oxidized prior to the fatigue
test. Results of thermo-mechanical fatigue tests on pre-aged and as-coated specimens gave evidence
of interaction between fatigue and ageing processes. An alternative approach is used, which is
focused on the evolution of a failure relevant damage parameter in the TBC system. The interfacial
fracture toughness was selected as a damage parameter, since one important failure mode of TBCs
is the spallation near the interface between the metal and the ceramic. Fracture mechanical
experiments based on indentation methods have been evaluated for monitoring the evolution of the
interfacial fracture toughness as a function of ageing time. It was found that the test results were
influenced by both changes of the interface (which is critical in service) and changes in the
surrounding material. |
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