Simulating the Effect of Depositing an 8YSZ Buffer Layer in P92/Al2O3 on the Thermal Cycles Endurance and Fracture Toughness of the System

Abstract

The effect of depositing 8YSZ between serving as an intermediate layer of the P92/Al2O3 was analyzed via finite element analysis. The result shows that depositing an 8YSZ buffer coat beneath the Al2O3 will dramatically decrease the maximum principal stress in the coating system in thermal shock. The stress intensity factor, KI, and J-integral are also decreased which indicates the crack propagation resistance is improved. Inserting a 100 nm 8YSZ buffer layer could reduce the KI and J-integral by 2 orders of magnitude. Thus, cracks are less likely to initiate and propagate. Moreover, coating an 8YSZ layer between the P92/Al2O3 can significantly change the stress distribution pattern in the Al2O3 coating. The 8YSZ with a proper coefficient of thermal expansion between that of the Al2O3 and P92 and good deformability is an ideal buffer layer to improve the thermal cycle endurance and prolong the service life of the Al2O3 coating.