Abstract
Advances in the functional properties of thermal barrier coating (TBC) deposits are important for increasing the efficiency of, and reducing emissions from both stationary and aircraft turbine engines. Computer modeling is the preferred method for developing new materials with minimum cost and development time. However, modeling of TBCs is complex and must take into account interactions among the layers and with the substrate, in-service phase changes, oxidation, and stress development. Understanding the microstructure of the ceramic layer is important for building these models, as it strongly influences the properties responsible for the basic TBC function – thermal resistance. As is well known the ceramic microstructure changes in service, potentially leading to coating and engine failure. A major challenge is ensuring that the model reliably describes the actual material. Thus, it is important to develop representative models, which can be related to real practical coating systems. We present such a model. It has been developed to interpret small-angle X-ray scattering data that characterize TBC ceramic deposit microstructures. This model is also suitable for incorporation into computer algorithms such as are used in finite-element analysis. Quantitative parameters that describe the microstructure changes occurring under service conditions are readily obtainable for current systems, and these can then be re-measured for future materials of interest.
