Double Rare-Earth Oxides Co-doped Strontium Zirconate as a New Thermal Barrier Coating Material

Y 2 O 3 and Yb 2 O 3 co-doped strontium zirconate with chemistry of Sr(Zr 0.9 Y 0.05 Yb 0.05 )O 2.95 (SZYY) was synthesized and had a minor second phase of Yb 2 O 3 . The SZYY showed good phase stability not only from room temperature to 1400 °C but also at high temperature of 1450 °C for a long period, analyzed by thermogravimetry-differential scanning calorimetry and x-ray diffraction, respectively. The coefficients of thermal expansion (CTEs) of the sintered bulk SZYY were recorded by a high-temperature dilatometer and revealed a positive influence on phase transitions of SrZrO 3 by co-doping with Y 2 O 3 and Yb 2 O 3 . The thermal conductivities of SZYY were at least ~30% lower in contrast to that of SrZrO 3 and 8YSZ in the whole tested temperature range. Good chemical compatibility was observed for SZYY with 8YSZ or Al 2 O 3 powders after a 24 h heat treatment at 1250 °C. The phase stability and the microstructure evolution of the as-sprayed SZYY coating during annealing at 1400 °C were also investigated.