Thermophysical Properties of TiO2 doped SmTaO4 ceramics

Abstract:

Thermal barrier coatings are one of the most important materials in gas turbine to protect the high temperature components. The SmTaO4 ceramics have excellent high-temperature phase stability and mechanical properties and show great potential for use as next-generation thermal barrier coating materials. In this paper, the TiO2-SmTaO4 ceramics have been prepared via high temperature solid-state reaction. The results show that that TiO2 doped SmTaO4 did not change the crystal structure of the SmTaO4 itself and its phase structure was still a single monoclinic phase. The TiO2-SmTaO4 ceramics doped with 2% mol have a second phase, which is inferred to as Sm0.33TaO7. The TiO2-SmTaO4 ceramics have a lower thermal conductivity (1.42 W?m?1?K?1 at 900 ℃) than 7–8-YSZ and SmTaO4（1.59W?m-1?K-1，900℃）, with a minimum nearly 30% lower than YSZ. The highest thermal expansion coefficient is detected in 2% TiO2-doped SmTaO4 ceramics (10.8×10-6K-1), which is much higher than that of YSZ (10.0×10-6K-1). Compared with pure SmTaO4, TiO2 doping increased the thermal expansion coefficient of TiO2-SmTaO4 ceramics. This indicates that TiO2-SmTaO4 ceramics have the potential to be employed as thermal barrier coatings.

Key words:TiO2-SmTaO4 ceramics; thermo-physical properties; thermal conductivity