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

In this current study, Sm 3 TaO 7 was used as the second phase to fabricate a composite ceramic with 7 wt.% Y 2 O 3 –ZrO 2 (7YSZ). Effective phonon scattering was achieved by controlling the content of the second phase Sm 3 TaO 7 , which significantly reduced the thermal conductivity . The results show that Sm 3 TaO 7 /7YSZ ceramics have a minimum thermal conductivity of 0.81 W m −1  K −1 at 900 °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 TaO 7 /7YSZ ceramics (12.1 × 10 −6  K −1 , 1200 °C), which was much higher than that for 7YSZ (∼10.0 × 10 −6  K −1 ). The hardness and Young's modulus of 5 wt.% Sm 3 TaO 7 /7YSZ ceramics were much lower than those of 7YSZ, which is clearly attributable to the low modulus and hardness of Sm 3 TaO 7 . Our experimental results showed that the 5 wt.% Sm 3 TaO 7 /7YSZ ceramics are excellent thermal barrier coating materials.