The influence of bond-coat thickness on the temperature distribution and stress level in thermal barrier coatings system

The paper presents the results of numerical calculation of the temperature distribution and thermal stresses in model of two layered thermal barriers coatings of DCL type deposited on the superalloy coupons with NiCrAlY bond-coat. The variable parameter was the thickness of bond-coat layers. In all cases it was assumed that the bond-coat would be the NiCrAlY type coat obtained by plasma spraying, just as the outer insulating layer. The thickness of the bond-coat layer is 100 μm to 300 μm. As the substrate material, the In 625 nickel superalloy was adopted. The insulation layer of TBC systems was built from outer sublayer based on La2Zr2O7 (LZO) ceramic and internal layer was built from conventional 8YSZ. A total thickness of insulation layer was assumed as 300 μm. Presented analysis showed that the overall thickness of bond-coat has important influence on the temperature distribution as well as the thermal stresses. The maximum temperature differences between extreme thickness value was calculated on the level of 50°C.