Thermophysical and mechanical properties of Sm3TaO7/7 wt.% Y2O3-ZrO2 ceramics

In this current study, Sm3TaO7 was used as the second phase to fabricate a composite ceramic with 7 wt.% Y2O3-ZrO2 (7YSZ). Effective phonon scattering was achieved by controlling the content of the second phase Sm3TaO7, which significantly reduced the thermal conductivity. The results show that Sm3TaO7/7YSZ ceramics have a minimum thermal conductivity of 0.81 W m(-1) K-1 at 900 degrees C. The minimum thermal conductivity of the composite was 50% lower than that of 7YSZ. The maximum thermal expansion coefficient was obtained for 5 wt. % Sm(3)TaO7/7YSZ ceramics (12.1 x 10(-6) K-1, 1200 degrees C), which was much higher than that for 7YSZ (similar to 10.0 x 10(-6) K-1). The hardness and Young's modulus of 5 wt.% Sm3TaO7/7YSZ ceramics were much lower than those of 7YSZ, which is clearly attributable to the low modulus and hardness of Sm3TaO7. Our experimental results showed that the 5 wt.% Sm3TaO7/7YSZ ceramics are excellent thermal barrier coating materials.