LÜ Jianguo ¹, ZHANG Haoming ², ZHANG Hongsong 2
(1. City College, Kunming University of Science and Technology, Kunming 650000, Yunan, China ; 2. School of Mechanical
Engineering, Henan Institute of Engineering, Zhengzhou 451191, Henan, China)

Abstract: Using Sm₂O₃, Gd₂O₃, Yb₂O₃ and Ce(NO₃) • 6H₂O as reactants,(Sm_0.5Gd_0.3Yb_0.2)₂Ce₂O₇ ceramic was prepared by sol-gel and solid reaction methods. Its phase composition was determined by X-ray diffraction, the microstructure was observed by scanning electronic microscope, and the thermal diffusivity and thermal expansion coefficient were measured by laser-flash method and pushing-rod method respectively. Results show that pure (Sm_0.5Gd_0.3Yb_0.2)₂Ce₂O₇ceramic with fluorite structure is synthesized successfully, it has a dense microstructure and the grain boundaries are very clean. The differences in mass and ionic radius between substituting atoms and substituted ions lead to the lower thermal conductivity of (Sm_0.5Gd_0.3Yb_0.2)2Ce₂O₇)₂Ce₂O₇ as compared to Sm₂Ce₂O₇, and its lower thermal expansion coefficient can also be attributed to the confused distribution of oxygen vacancies.

Key words: thermal barrier coatings; rare earth cerium; thermal conductivity; thermal expansion coefficient