Microstructures and mechanical properties of ceramic/metal gradient thermal barrier coatings

The ceramic/metal gradient thermal barrier coatings (CMGTBCs) which combined the conceptions of thermal barrier coatings (TBCs) and functional gradient materials (FGMs) are investigated. The structure model studied in this paper is a general model which includes four different layers: pure ceramic layer, ceramic/metal gradient layer, pure metal layer, and substrate layer. The microstructures of gradient layer have different ceramics and metal volume fraction profile along with the direction of thickness. The profile function used to describe the gradient microstructures can be expressed in power-law or polynomial expression. The mechanical properties of CMGTBCs are obtained by means of microscopic mechanics. As special cases, the interactive solutions are given by Mori-Tanaka method, and the non-interactive solutions by dilute solution. The Young's modulus calculated by these methods are compared with those by other methods, e g, the rule of mixtures.