Effect of the Porosity on Thermal Stress within TBCs Using Finite Element Method

Thermal barrier coatings (TBCs) with NiCoCrAlY bond-coats (BC) and ceramic top coats (TBC) were prepared on IN738 superalloy by plasma spraying technology. Effect of porosity on the maximum stress under thermal cycling conditions was carried out by using finite element software ANSYS. The results showed that maximum axial thermal tensile stress in TBCs decreases from 868MPa to 498MPa with the increase of bond-coats porosity near the TGO/BC interface, and the maximum axial thermal compressive stress decreases from 1060MPa to 711MPa. The stress distribution changes with increasing bond-coats porosity near the TGO/BC interface. The simulation results are in agreement with the experiments, exhibiting a clearly evidence that the porous TBCs have a longer lifetime.