An Analytical Model of the Thermal Conductivity of Thin Porous Ceramic Coatings

Thermal conductivity is a key property of thermal barrier coatings, which play a critical role in protecting components in high-temperature environments such as gas turbines and jet engines. This paper presents an analytical model for evaluating the thermal conductivity of thin, porous ceramic thermal barrier coatings. The analytical model incorporates factors such as porosity, pore orientation, and aspect ratio, which are extracted from scanning electron microscopy images. The model, which provides a comprehensive understanding of heat transfer mechanisms within coatings, was verified through comparisons with numerical simulation results from a multiphysics software tool and experimental measurements. Overall, the study provides insight into the factors affecting the thermal conductivity of porous yttrium-stabilized zirconia coatings and presents an analytical method to predict conductivity based on the coating's microstructure. Since the microstructure evolves during the service, a time-dependent thermal conductivity can be predicted if the microstructure changes over time become available. The model offers capabilities beyond those of conventional numerical models and demonstrates good agreement with experimental measurements of thermal conductivity. The information is critical for the design of thermal barrier coatings systems and thermal performance evaluation during service.