Uneven growth of thermally grown oxide and stress distribution in plasma-sprayed thermal barrier coatings

After isothermal exposure at 1050 °C, uneven growth of thermally grown oxide (TGO) was observed at peak and valley positions of rough top coat/TGO interface. A statistical, quantitative analysis on uneven TGO and its evolution with oxidation time were presented. The stress states in the vicinity of uneven TGO were investigated using a finite element (FE) method. The results show that the TGO at peak and valley locations obeys exponential growth. The TGO is thicker at peaks than at valleys. A significant difference in the stress distribution exists for even and uneven TGO.