Preparation and thermophysical properties of Dy2Zr2O7 ceramic for thermal barrier coatings

A rare earth zirconate (Dy2Zr2O7) ceramic for thermal barrier coatings (TBCs) was synthesized by solid state reaction at 1600 °C for 10 h. The phase composition, microstructure, thermophysical properties of the material were investigated. XRD results revealed that single phase Dy2Zr2O7 with fluorite structure was synthesized and the SEM showed that the microstructure of the product was dense and no other phases existed among the particles. With the temperature increasing, the thermal expansion coefficient (TEC) of the ceramic increased, while the thermal conductivity decreased. The thermophysical results indicated that TEC of the ceramic was slightly higher than that of conventional Y2O3-8wt.%ZrO2 (8YSZ) and the thermal conductivity of the ceramic was much lower than that of 8YSZ. The lower thermal conductivity of Dy2Zr2O7 was mainly attributed to more oxygen vacancies and larger atomic weight of substitutional atom. These results imply that Dy2Zr2O7 can be explored as the candidate material for the ceramic layer in TBCs system.