The effect of pore morphology on thermal insulation properties of thermal barrier coatings

Abstract

The inhomogeneous-geometry microstructures caused by pores make thermal barrier coatings (TBCs) to have excellent thermal insulation properties, thus ensuring that the superalloy matrix is stable in its service at higher temperatures. Consequently, significant attention has been paid to understand the relationship between pore morphology and thermal conductivity. However, unclear the influence mechanisms of pore morphology-thermal insulation properties leads to a poor guide to the structural tailoring for better thermal insulation for TBC. In this study, a finite element method was used to simulate the thermal transport behavior of porous structures, and the influence mechanism of pore morphology on the thermal transport behavior of coatings was clarified. It indicated that thermal conductivity has a significant dependence on the pore aspect ratio, orientation angle, and porosity. The thermal insulation properties would be enhanced when large aspect ratio prolate spheroids are inserted with a pillar at the center. Further, the results shed light on the heat transport process across highly porous structures and provide a guide to design the coating with high thermal insulation properties.