TY  - JOUR
AU  - Mack, Daniel E.
AU  - Wobst, Tanja
AU  - Jarligo, Maria Ophelia D.
AU  - Sebold, Doris
AU  - Vaßen, Robert
TI  - Lifetime and failure modes of plasma sprayed thermal barrier coatings in thermal gradient rig tests with simultaneous CMAS injection
JO  - Surface and coatings technology
VL  - 324
SN  - 0257-8972
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - FZJ-2017-06802
SP  - 36 - 47
PY  - 2017
AB  - Degradation of thermal barrier coatings (TBCs) in gas-turbine engines due to calcium–magnesium–aluminosilicate (CMAS) glassy deposits from various sources such as sand, volcanic ash, fly ash, or variable quality fuels has been a tenacious issue during the recent years. This follows from the fact that engines are required to operate under increasingly harsh conditions in all kind of gas turbine applications following the demands for higher efficiency and operational flexibility. While the understanding of the mechanism of CMAS induced degradation of TBCs as well as approaches for mitigation of CMAS attack by means of advanced TBC compositions have grown remarkably, most of the reported results have been obtained from lab testing at isothermal conditions or from evaluation of ex-service components, either. The isothermal tests are not reproducing important thermomechanical effects from service conditions, and it may be hard to figure out the thermal history of the ex-service examples.In this study a burner rig facility has been used for the evaluation of TBC performance, where a thermal gradient is applied across the TBC at cyclic load and CMAS is continuously injected to the combustion environment to simulate the conditions closer to actual service in an engine while allowing control of important degradation limiting parameters. Tests have been performed on the state of the art material YSZ while loading parameters as high temperature dwell time and CMAS deposition rate have been varied. Tests have been evaluated in terms of chemical degradation, failure mode and TBC spallation lifetime by means of SEM, EDS and XRD. Test conditions and relevance to in-service operating conditions are discussed. Major impacts on thermal gradient cycling lifetime and similarities and discrepancies related to reported failure mechanism are reviewed.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000406988200005
DO  - DOI:10.1016/j.surfcoat.2017.04.071
UR  - https://juser.fz-juelich.de/record/838064
ER  -