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Evolution of porosity, crack density, and CMAS penetration in thermal barrier coatings subjected to burner rig testing
Author(s) -
Mack Daniel E.,
Laquai Rene,
Müller Bernd,
Helle Oliver,
Sebold Doris,
Vaßen Robert,
Bruno Giovanni
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16465
Subject(s) - thermal barrier coating , materials science , yttria stabilized zirconia , porosity , cubic zirconia , composite material , wetting , combustor , metallurgy , ceramic , combustion , chemistry , organic chemistry
Abstract Degradation of thermal barrier coatings (TBCs) in gas‐turbine engines due to calcium–magnesium–aluminosilicate (CMAS) glassy deposits from various sources has been a persistent issue since many years. In this study, state of the art electron microscopy was correlated with X‐ray refraction techniques to elucidate the intrusion of CMAS into the porous structure of atmospheric plasma sprayed (APS) TBCs and the formation and growth of cracks under thermal cycling in a burner rig. Results indicate that the sparse nature of the infiltration as well as kinetics in the burner rig are majorly influenced by the wetting behavior of the CMAS. Despite the obvious attack of CMAS on grain boundaries, the interaction of yttria‐stabilized zirconia (YSZ) with intruded CMAS has no immediate impact on structure and density of internal surfaces. At a later stage the formation of horizontal cracks is observed in a wider zone of the TBC layer.