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:
The lifetime under thermal cycling of a system consisting of an air plasma sprayedthermal barrier coating (TBC) deposited on a metallic bondcoat (BC) is determined by the subcriticalgrowth of micro-cracks near the interface between both coatings. This growth mainly occursduring the cooling down phase, as shown by the acoustic emission monitoring during the thermalcycling. The factors controlling the stress level leading to the crack growth are the local curvatureof the metallic-ceramic interface, the growth of an oxide scale (TGO) at such interface and thesintering of the TBC, the two last processes occurring during the high temperature cycle phase.Implementing all these factors, a model based on Finite Element Method (FEM) calculations ispresented where growing cracks are incorporated by assigning soft properties to the FEM cellsoccupied by the cracks. Determining the growth direction for the maximum energy release rate atevery cooling down step, the current crack extension during the cycling is tracked until it reaches acharacteristic length corresponding to the TBC failure. The influence by the metallic-ceramicinterface roughness and by the temperature gradient across the TBC is discussed
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/53/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.333.263.pdf
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