Comparison of thermal stresses developed in Al2O3-SG, ZrO2-(12% Si+Al) and ZrO2-SG thermal barrier coating systems with NiAl, NiCrAlY and NiCoCrAlY interlayer materials subjected to thermal loading

Abstract

In this investigation, thermal and structural finite element analysis has been employed to analyse the level of stresses developed in Al2O3-spherical cast iron (SG), ZrO2-(12% Si + Al) and ZrO2-SG coatings subjected to thermal loading. Coatings with a coating-to-substrate thickness ratio of 1/10 were modelled. ZrO2-SG coatings with an NiAl, NiCrAlY or NiCoCrAlY interlayer, and with different combinations of these interlayer materials, were also modelled. Nominal and shear stresses at the critical interface regions (film/interlayer/substrate) were obtained and compared. The results showed that the ZrO2-SG coatings have a higher thermal shock resistance than the Al2O3-SG and ZrO2-(12% Si + Al) coating systems. Furthermore, the interlayer thickness and material combinations have a significant influence on the level of thermal stresses developed. It is also concluded that the finite element technique can be used to optimise the design and processing of ceramic coatings. (C) 1999 Elsevier Science S.A. All rights reserved.