11:30 AM *BB7.3
RESIDUAL STRESS GENERATION IN
THERMAL BARRIER COATINGS. William J. Brindley, NASA
Lewis Research Center, Cleveland, OH; Andrew M. Freborg, B. Lynn
Ferguson, DCT, Inc., Cleveland, OH.
The mechanisms
by which oxidation and thermal cycling cause thermal barrier coating
(TBC) failure are not well understood. A very general explanation is
that oxidation and thermal cycling cause increasing residual stresses
and/or decreasing coating strength. However, this explanation
provides no mechanistic basis from which to predict TBC behavior. A
finite element study has been conducted to examine thermal cycle
residual stress generation in a TBC as a function of materials
properties, with an emphasis on bond coat properties. The results
indicate that oxidation of the bond coat, bond coat creep, top coat
creep and bond coat thermal expansion coefficient can all have a
strong influence on stresses in the ceramic layer, both individually
as well as through property interactions. Results of an investigation
of oxide growth stress effects and thermal cycle hot time effects on
TBC stresses will also be presented.
SESSION BB8: MECHANICAL PROPERTIES - B
Chairs: Daniel
Sordelet and Subra Suresh
Thursday Afternoon, December 4, 1997
Essex North/Center (W)
