Preparation, microstructure and properties of ternary Al2O3/YAG/ZrO2 ceramics hot pressed with eutectic composition powders

Abstract:

Al₂O₃/YAG/ZrO₂ powders with eutectic composition have been synthesized by the chemical co-precipitation in acohol-water aqueous solution and calcination method, and are characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The precursors were calcined at temperatures of 600_oC-1350_oC in air, and the phase transition process was then revealed with increasing the calcination temperature. Al₂O₃/YAG/ZrO₂ powders calcined at 1300_oC for 1h consist of α-Al₂O₃, YAG and c-ZrO₂ phases. Al₂O₃/YAG/ZrO₂ ceramics with eutectic composition were hot-pressed at 1550_oC with the above-mentioned powders. The Al₂O₃/YAG/ZrO₂ ceramic sintered at 1550_oC contains an intragranular microstructure, and exhibits a relative density of 98.8%, a room-temperature flexural strength of 420 MPa, a fracture toughness of 3.69 MPa.m_1/2 and a high-temperature (1000_oC) flexural strength of 464MPa, respectively. The formation mechanism of an intragranular microstructure in the Al₂O₃/YAG/ZrO₂ ceramic has been proposed.