Preparation and characterization of Al2O3–25 mol% ZrO2 composites

Al2O3–ZrO2 (AZx), with 25 mol% ZrO2 content, was prepared using the co-precipitation method. Synthesized powders were characterized by thermal reaction using a differential thermal analysis technique (TG–DTA) and were investigated by phase formation using X-ray diffraction. It indicated that the reaction occurred at 850 °C; cubic (c)-ZrO2 phase and Al2O3 were obtained. By increasing temperature to 1100 °C, tetragonal (t)-ZrO2 phase was detected. The Al2O3–25 mol% ZrO2 was sintered for 2 h in the temperature range of between 1300 and 1600 °C. The majority phases of ceramics were m-ZrO2 and α-Al2O3, although a t-ZrO2 phase also appeared as a minor phase and decreased with higher temperature. Moreover, morphology and particle size evolution have been determined via the SEM technique. SEM showed that the particles of powder are agglomerated and basically irregular in shape. An SEM micrograph of ceramics exhibits uniform microstructure without abnormal grain growth.