Thermophysical Properties of Sintered SrY 2 O 4 and the Related Compounds Applicable to Thermal Barrier Coating Materials

Abstract

Polycrystalline samples of SrY 2 O 4 were prepared by reacting the appropriate amounts of Y 2 O 3 and SrCO 3 . The sample of SrY 2 O 4 was sintered by using Spark Plasma Sintering (SPS). The dense sample with about 99 % of theoretical density is obtained in the present study. The crystal structure and lattice parameters were evaluated with an X-ray diffraction method. SrY 2 O 4 have an orthorhombic structure with the space group Pnam. The thermal expansion coefficient was measured with a differential dilatometer in the temperature range from 300 K to 1773 K. The average liner thermal expansion coefficient is 10.7x10 -6 K -1 . The heat capacity was measured using a differential scanning calorimeter (DSC). The thermal diffusivity was measured with a laser flash method in the temperature range between room temperature and about 1273 K. The thermal conductivity was evaluated from the measured heat capacity and thermal diffusivity. The elastic moduli and Debye temperature were evaluated from the longitudinal and shear sound velocities, which were measured with an ultrasonic pulse-echo method at room temperature in air. The Young's modulus of SrY 2 O 4 is 162 GPa.