Effect of thermal treatment at high temperature on phase stability and transformation of Yb2O3 and Y2O3 co-doped ZrO2 ceramics

Y2O3 doped ZrO2 (YSZ) ceramic material is used to protect alloy components worked in high-temperature. But its phase transformation occurred at high temperate leads to YSZ invalid. This study explored the process of phase changes of YSZ at high temperature. Besides, the phase stability and transformation details of Yb2O3 and Y2O3 co-doped ZrO2 (YbYSZ) ceramics were also discussed. The ceramic samples were synthesized using a solid-state reaction method. The results of X-ray diffraction and Raman spectra displayed that all bulks exhibited almost the same crystal structure. The phase transformation investigation through the thermal treatment at 1300 °C demonstrated that YbYSZ ceramics had better phase stability than YSZ. The content of the monoclinic phase calculated according to X-ray diffraction of ceramic samples heat-treated at 1300 °C for 0 – 358 hours showed a sigmoidal behavior. The content change of monoclinic phase of YbYSZ ceramics with heat treatment time at 1300 °C can be divided into three stages: (I) diffusion progress accompany by the transformation of t′→t+c→t+c+m, (II) drastic change from tetragonal phase to monoclinic phase, and (III) the content of monoclinic phase gets saturation.