Vergleich zwischen experimentell beobachteten Versagensmustern und berechneten Spannungsverteilungen in thermisch belasteten ebenen und gekrümmten 8YSZ Wärmedämmschichten
Kerkhoff, Gerold (Corresponding author)
Publikationen vor 2000; PRE-2000; Retrocat
Jülich Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag 2000
XII, 125 p.
Report
Book
Addenda
Berichte des Forschungszentrums Jülich 3784
OpenAccess
OpenAccess
Please use the identifier: http://hdl.handle.net/2128/24003 in citations.


The main task in the field of turbine development is the increase of their life-time andefficiency and the reduction of toxic emissions. These can be achieved by raising the hot gasinlet temperature. Today the temperature resistance of the metallic turbine blades is raised byapplying duplex coating systems consisting of a vacuum plasmasprayed NiCoCrAlY bondcoatand an atmospheric plasma sprayed 7-8 wt% Y$_{2}$O$_{3}$-ZrO$_{2}$ thermal barrier coating. Togetherwith the internal cooling of the blades a temperature gradient of 200 K can be obtained in a300 $\mu$m thick thermal barrier coating.Thermal barrier coatings can only be used to full extend, if a minimum life-time can bepredicted exactly. Due to the complexity of the coating system und due to the numerouscharacteristics of the thermal barrier coating material which can have detrimental effects lifetimepredictions are not yet available.This study deals with analytical and numerical (FE) modelling of stress distributions incoating systems under cyclic thermal loading. The results were verified by X-ray stressmeasurements and microstructural investigations. Mainly, the influence of differentgeometrical parameters, of different roughness profiles of the bondcoat surface and of theoxidation of the bondcoat an the stress distributions were investigated. The results werediscussed by the use of fracture mechanics concerning their applicability for determining lifetimesof thermal barrier coatings.lt became evident that by calculating the dynamics of stress distributions crack initiation inthermal barrier coatings can be localized and that crack propagation can be estirnated.However, for concrete life-time predictions research in the field of crack propagationdynamics in plasma sprayed thermal barrier coatings is still necessary.