Local accumulation of thermally grown oxide in plasma-sprayed thermal barrier coatings with rough top-coat/bond-coat interfaces

After thermal cycle exposure, multilayered accumulation of thermally grown oxide (TGO) was observed locally on the tops of the roughness protrusions of the bond coat in thermal barrier coatings. This phenomenon is attributed to the repeated separation and growth of the TGO. The TGO accumulation caused cracking in the top coat.