Thermal expansion and thermal conductivity of SmxZr1−xO2−x/2 (0.1 ≤ x ≤ 0.5) ceramics

A study was conducted of the effect of additions of samarium oxide on the thermal expansion and thermal conductivity of zirconium oxide for thermal barrier coatings. SmxZr1−xO2−x/2 (0.1 ≤ x ≤ 0.5) ceramic powders synthesized with a chemical-coprecipitation and calcination method were sintered at 1873 K for 15 h. Structures of the synthesized powders and sintered ceramics were identified by X-ray diffractometer. The morphologies of ceramic powders were observed by transmission electron microscope. The thermal expansion coefficients and thermal diffusion coefficients of SmxZr1−xO2−x/2 ceramics were studied with a high-temperature dilatometer and a laser flash diffusivity technique from room temperature to 1673 K. The thermal conductivity was calculated from thermal diffusivity, density and specific heat of bulk ceramics. Sm0.1Zr0.9O1.95 ceramics consists of both monoclinic and tetragonal structures. However, Sm0.2Zr0.8O1.9 and Sm0.3Zr0.7O1.85 ceramics only exhibit a defect fluorite structure. Sm0.4Zr0.6O1.8 and Sm0.5Zr0.5O1.75 ceramics have a pyrochlore-type lattice. With the increase of Sm2O3 content, the linear thermal expansion of SmxZr1−xO2−x/2 ceramics increases except for Sm0.1Zr0.9O1.95. The thermal conductivities of SmxZr1−xO2−x/2 ceramics ranged from 1.41 at 873 K to 1.86 W m−1 K−1 at room temperature in a test temperature range of room temperature to 1673 K, and the results can be explained by phonon scattering mechanism.