Thermal barrier coatings (TBCs) provide thermal insulation and oxidation protection of Ni-base super-alloys in elevated temperature turbine applications. Thermal barrier coating failure is caused by spallation, which is related to the development of internal stresses during thermal cycling. Recent microstructural observations have highlighted the occurrence of a martensitic bond coat transformation, and this finite-element analysis was conducted to clarify the influence of the martensite on the development of stresses and strains in the multilayered system during thermal cycling. Simulations incorporating the volume change associated with the transformation and experimentally measured coating properties indicate that out-of-plane top coat stresses are greatly influenced by the presence of the martensitic transformation, the temperature at which it occurs relative to the strength of the bond coat and attendant bond coat plasticity. Intermediate values of bond coat strength and transformation temperatures are shown to result in the highest top coat stresses.
|Number of pages||8|
|Journal||Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science|
|Publication status||Published - 2004 Aug|
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys