Concept of Advanced Thermal Barrier Functional Coatings in High Temperature Engineering Components

Abstract

In conventional thermal barrier coatings (TBCs) the major problem is the spalling of a ceramic coating. This could be due to the large thermal stresses which are generated during thermal cycling on the oxidizing environment. One of the ways to improve the life span and overcome mentioned problems is introducing the concept of functionally graded materials (FGM) into the TBC. Functionally graded materials are referred to as a class of advanced materials that are distinguished by variation in their properties with varying their dimensions. Through employing a functionally graded thermal barrier coating (FG-TBC), an intermediate layer with a gradual compositional variation is embedded between the top and the bond coats. This layer(s), composed of ceramic and metal in various ratios, can achieve a gradual composition variation, thereby leading to gradual changes in microstructures and better mechanical and physical properties.