Yb2O3-Gd2O3codoped strontium zirconate composite ceramics for potential thermal barrier coating applications

Strontium zirconate (SrZrO3) has been considered as a promising thermal barrier coating (TBC) material for application in gas turbine engines; however, the phase transition problem limits its application. In this study, an Yb(2)O(3)and Gd(2)O(3)codoped SrZrO(3)system with excellent properties was reported. Yb2O3-Gd(2)O(3)codoped SrZrO(3)ceramic powders [Sr-0.8(Zr0.9Yb0.05Gd0.05)O-2.75, SZYG/YGZO], [Sr(Zr0.9Yb0.05Gd0.05)O-2.95, SZYG] and pure SrZrO3(SZO) powders were produced by a conventional solid-state reaction method. The XRD and Raman results show that, the composite SZYG/YGZO ceramics consist of the SZO and Yb(0.5)Zr(0.5)O(1.75)phases with a low thermal conductivity of ~1.3 W/(m center dot K) at 1000 degrees C, which is at least 40% lower than that of the SZO ceramics. The TG-DSC results show that the SZYG/YGZO ceramics have no phase transition in the temperature range of 600 to 1400 degrees C. The thermal expansion coefficient of the SZYG/YGZO ceramics reaches 10.9 x 10(-6) K-1(1250 degrees C). In addition, the fracture toughness of the SZYG/YGZO ceramics increases by more than 30% compared with the SZO ceramics, and this can be attributed to the presence of the Yb(0.5)Zr(0.5)O(1.75)phase.