Evaluation of Coating Properties of Thermal Barrier Coatings by Leeb Hardness Testing

Abstract

In order to explore the possibility of evaluating mechanical and thermal properties of thermal barrier coatings (TBCs) by Leeb hardness (HL) test, relationship between mechanical properties and HL value was examined on TBC plate-shaped specimen which was exposed to a high temperature atmosphere. A finite element (FE) analysis of the sphere impact process was firstly performed on a double-layered plate model in order to discuss the experimental relations. Obtained results can be summarized as follows: (1) Results of high temperature exposure tests showed a clear correlation between HL value and Young’s modulus and also thermal conductivity. (2) The FE analysis obtained here supported the relationship between the mechanical properties in TC layers and HL value. Consequently, it was confirmed that Leeb hardness test had capability of non-destructive testing method for assessing the Young’s modulus and thermal conductivity of top coat layer in TBCs.