Preparation of Al2O3-GdAlO3-ZrO2 eutectic ceramics by flash sintering

Al2O3-based eutectic ceramics have excellent high-temperature mechanical properties，showing great application prospects in the field of extreme environments. Therefore， it is of great significance to explore the preparation method with low energy consumption and simple process for its industrial application. The Al2O3-GdAlO3-ZrO2 eutectic ceramics are successfully prepared by flash sintering technique. The effects of electric field strength， current limit and flash sintering time on flash sintering behavior， phase and microstructure morphology are studied. The results show that the flash sintering temperature decreases with the increase of electric field strength. Under the electric field strength of 600， 700， 800， 900 V/cm， the flash temperature of Al2O3-Gd2O3-ZrO2 mixed powder is 994， 958， 943， 911 ℃， respectively. Al2O3-GdAlO3-ZrO2 eutectic ceramics are obtained at an electric field strength of 900 V/cm and a flash temperature of 911 ℃. With the increase of current limit and flash sintering time， the irregular eutectic structure transforms into a regular eutectic structure， and the eutectic structure becomes finer. The electric field strength has no significant effect on the morphology of the eutectic structure. The Joule heating effect plays an important role in the formation of eutectic structure. However， it is difficult to fully explain the formation of eutectic structure in the flash sintering process only by the Joule heating effect.