抄録
Single phase m-ZrO2 ceramics (∼13mmφ and 3-5mmt) have been fabricated using a piston-cylinder type high-pressure apparatus under 1GPa at 1023-1173K, in which a newly developed high-pressure cell has been utilized to introduce pseudo-isostatic pressure. Starting material, meta-stable m-ZrO2 powder prepared via a sol-gel method, was characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), and transmission electron microscopy (TEM). Dense ceramics sintered at 1123K, free from macro-cracks, showed a high relative density of ∼ 99.5% and homogeneous microstructures consisting of fine grains (∼1μm). In-situ XRD analysis under high pressures and temperatures revealed that m- to t-ZrO2 transition took place around 1123K under 1GPa. Mechanical properties of m-ZrO2 ceramics have been evaluated ; the maximum values of bending strength (σb = 520MPa), Vickers hardness (Hv = 9.8GPa), and fracture toughness (KIC = 3.9MPa·m1/2) were achieved at the samples fabricated at 1123K.
