Abstract
Abstract In this study, Ce1−x Sm x O2−x/2 ceramics were synthesized by sol–gel route and solid state sintering method. The phase structure was analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy. The morphologies of the synthesized powders and the corresponding bulk samples were observed using scanning electron microscopy (SEM). Their thermal diffusivities and thermal expansion coefficients were measured by the laser-flash method and the pushing-rod method, respectively. Results show that pure Ce1−x Sm x O2−x/2 powders with single fluorite structure are synthesized successfully, and their microstructures of the corresponding bulk samples are very dense. With the increase of Sm2O3 content, their thermal expansion coefficients decrease due to the higher electro-negativity of Sm3+ ions as compared with that of Ce4+ ions. Their thermal conductivities at 1000 °C lie in the range of 1.62–2.02 W/(m·K) due to the phonon scattering caused by the substituted atoms and oxygen vacancies. The Ce1−x Sm x O2−x/2 ceramics can be used as ceramic candidates for novel thermal barrier coatings (TBCs).
Highlights
Thermal barrier coatings (TBCs) are advanced material system which is always used to protect underlying metallic components in turbine engines from damage caused by corrosive hot gas or high temperature [1,2,3]
In the system of thermal barrier coatings, the ceramic top coat shields the underlying material from heat, and the metallic bond protects the substrate against high temperature degradation and improves adherence of the top coat [4]
The X-ray diffraction patterns of the synthesized powders are displayed in Fig. 1 together with the data of CeO2
Summary
Thermal barrier coatings (TBCs) are advanced material system which is always used to protect underlying metallic components in turbine engines from damage caused by corrosive hot gas or high temperature [1,2,3]. The excellent ceramic candidates for TBCs must possess a few important performances, such as low thermal conductivity, appropriate thermal expansion, www.springer.com/journal/40145. J Adv Ceram 2016, 5(3): 244–252 good phase stability at high temperature, low sintering rate, high melting point, chemical inertness, and good adherence to the metal substrate [7]. Low thermal conductivity and appropriate thermal expansion coefficient have been regarded as the primary selection criterions of the ceramic materials for TBC applications. The rare earth doped CeO2 (RE2O3–CeO2) have been considered to be new materials for TBCs and solid oxide fuel cells due to the excellent electrical, mechanical, and thermophysical properties [15,16,17].
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