Micromechanical analysis of failure in thin protective coatings

The integrity of protective coatings is the subject of this investigation. Specifically, we concentrate on the case of thermo-protective coatings, so-called thermal barrier coatings, aiming at development of methodology for service life estimation of the coated components under thermal loading. At the current phase of the development, we establish relationships between various thermal loading patterns and failure driving parameters at different failure stages by developing an analytical–computational model of the process. The analysis addresses a typical failure development pattern consisting of a system of multiple surface cracks leading to and branching along or near the interface between the coating and the base material. The process is driven by thermal stresses. The developed model is applicable to thin coatings and provides insight into the processes taking place during failure development and the effect of the details of the applied thermal loading. The methods developed in the course of this investigation may be applied to the analysis of environmental effects on protective coatings and to investigations of failure development in layered composite systems under general loading conditions.