Surface-Roughness Induced Residual Stresses in Thermal Barrier Coatings: Computer Simulations

Conference · Mon Oct 26 04:00:00 EST 1998

OSTI ID:1741

Becher, P F ^[1]; Carter, C; Fuller, Jr, E R; Hsueh, C H; Langer, S A

---

1. ORNL

Adherence of plasma-sprayed thermal barrier coatings (TBC'S} is strongly dependent on mechanical interlocking at the interface between the ceramic coating and the underlying metallic bond coat. Typically, a rough bond-coat surface topology is required to achieve adequate mechanical bonding. However, the resultant interfacial asperities modify the residual stresses that develop in the coating system due to thermal expansion differences, and other misfit strains, and generate stresses that can induce progressive fracture and eventual spallation of the ceramic coating. For a flat interface the principal residual stress is parallel to the interface as the stress normal to the interface is zero. However, the residual stress normal to the interface becomes non-zero, when the interface has the required interlocking morphology. In the present study, an actual microstructure of a plasma-sprayed TBC system was numerically simulated and analyzed with a recently developed, object-oriented finite element analysis program, OOF, to give an estimate of the localized residual stresses in a TBC system. Additionally, model TBC rnicrostructures were examined to evaluate the manner in which the topology of interfacial asperities influences residual stresses. Results are present for several scenarios of modifying interfacial roughness.

• Research Organization: Oak Ridge National Laboratory; Oak Ridge, TN
• Sponsoring Organization: USDOE Office of Energy Research (ER)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 1741
• Report Number(s): ORNL/CP-99990; KC 02 01 01 0; ON: DE00001741
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
99 GENERAL AND MISCELLANEOUS
Computerized Simulation
Finite Element Method
Microstructure
O Codes
Plasma
Residual Stresses
Roughness
Surface Coating