ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Strategies for time-economic lifetime assessment of thermal barrier coatings (TBC) inservice are described and discussed on the basis of experimental results, achieved on materialsystems with coatings applied by electron beam physical vapour deposition. Service cycles for gasturbine blades have been simulated on specimens in thermo-mechanical fatigue tests, acceleratingthe fatigue processes by an increase of load frequency. Time dependent changes in the materialsystem were imposed by a separate ageing, where the samples were pre-oxidized prior to the fatiguetest. Results of thermo-mechanical fatigue tests on pre-aged and as-coated specimens gave evidenceof interaction between fatigue and ageing processes. An alternative approach is used, which isfocused on the evolution of a failure relevant damage parameter in the TBC system. The interfacialfracture toughness was selected as a damage parameter, since one important failure mode of TBCsis the spallation near the interface between the metal and the ceramic. Fracture mechanicalexperiments based on indentation methods have been evaluated for monitoring the evolution of theinterfacial fracture toughness as a function of ageing time. It was found that the test results wereinfluenced by both changes of the interface (which is critical in service) and changes in thesurrounding material
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.333.147.pdf
