Surface and Coatings Technology
The initiation of a class of fatigue cracks observed in thermal barrier coatings (TBCs) subjected to thermal gradient mechanical fatigue testing is investigated. The coating system is based on a NiCoCrAlY bond coat and a partially yttria stabilized zirconia top coat. To explain the development of the cracks of interest, the thermo-mechanical response of the bond coat and the thermally grown oxide (TGO) is examined and quantified through finite element analyses. The models include non-linear and time-dependent behavior such as creep, TGO growth stress, and thermo-mechanical cyclic loading. The simulations suggest that stress-redistribution due to creep can lead to tensile stresses in the TGO during TGMF testing that are large enough to initiate the cracks investigated.
Hernandez, M. T., Karlsson, A. M., and Bartsch, M., 2009, "On TGO Creep and the Initiation of a Class of Fatigue Cracks in Thermal Barrier Coatings," Surface & Coatings Technology, 203(23) pp. 3549-3558.
NOTICE: this is the author’s version of a work that was accepted for publication in Surface and Coatings Technology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Surface and Coatings Technology, 203, 23, (08-25-2009); 10.1016/j.surfcoat.2009.05.018