Effects of splat interfaces, monoclinic phase and grain boundaries on the thermal conductivity of plasma sprayed yttria-stabilized zirconia coatings

Abstract

Microstructure has a significant influence on the thermal conductivity of thermal barrier coating (TBC) systems. In this work, the microstructures including splat interface, monoclinic phase and grain boundaries in the YSZ air plasma spraying (APS) TBC systems are investigated. A finite element simulation model based on electron backscatter diffraction (EBSD) images is established. It is found that the simulation results of thermal conductivity are in good agreement with the experimental results. Using this model, the effect coefficient of splat interface, monoclinic phase and grain boundaries on thermal conductivity are calculated. Results show that the splat interface influences the thermal conductivity of the TBCs. Those results provide important guidance for reducing the thermal conductivity of thermal barrier coatings.