On the failure mechanisms of thermal barrier coatings with diffusion aluminide bond coatings

The major findings are that the durability is enhanced by removing imperfections on the surface of the bond coat, as well as by surface pre-treatments that diminish subsequent TGO thickening and by incorporating a reactive-element in the substrate that strengthens the bond coat upon inter-diffusion during manufacture. These effects are consistent with the expectations of a TGO instability mechanism, driven by a combination of growth and thermal expansion misfit strains in the TGO. The grain structure of the bond coat also affects failure through its influence on the TGO instability sites.