One-step preparation of CaO-doped partially stabilized zirconia from fused zirconia

Abstract Partially stabilized zirconia (PSZ) replaces the widespread applications of full stabilized zirconia (FSZ) on ceramics materials and refractories materials, attributed to its excellent properties including small coefficient of thermal expansion, low thermal conductivity and good thermal shock resistance. In this work, CaO-doped partially stabilized zirconia (CaO-PSZ) was optimizedly prepared from fused zirconia through conventional roasting. Meanwhile, the effects of roasting temperature and duration time on stability properties were explored to determine the stability parameters of the prepared CaO-PSZ. Results indicated that the zirconia stability rate synchronously improved with the decrease of roasting temperature and duration time, which was attributed to that the martensitic transformation of fused zirconia with volume change plays a toughening effect, further rendering the change of zirconia stability properties. XRD patterns verified the martensitic transformation, representing by cubic ZrO2 phase (c-ZrO2) in raw fused zirconia was partially transformed into monoclinic ZrO2 phase (m-ZrO2) at 1450 °C for 4 h. Moreover, the phase transition law of fused zirconia was revealed through SEM and EDAX characterization for the raw fused zirconia and the prepared CaO-PSZ. SEM patterns showed acicular patterns of grains and round fine particles clustered at grain boundaries, indicating that CaO stabilizer precipitated on grain boundaries and rendered the crystal structure enhanced, which the result was consistent with EDAX analysis. This work can lay a significant foundation for applications of microwave heating on the preparation of partially stabilized zirconia (PSZ) from fused zirconia.