Influence of Y2O3 Addition on the Microstructure and Mechanical Properties of Mg-PSZ Ceramics

Y-TZP (yttria tetragonal zirconia polycrystalline) exhibit high strength and toughness. However these ceramics degrade at low temperatures, especially when exposed to humid environments, where tetragonal to monoclinic transformation occurs because of reaction of water with tetragonal grains of Y-TZP. Mg-PSZ (magnesia partially stabilized zirconia) has better resistance to low temperatures. The addition of Y2O3 to Mg-PSZ is known to improve its mechanical properties by decreasing eutectoid decomposition. Mg-PSZ and Y-Mg-PSZ (yttria magnesia partially stabilized zirconia) powders were prepared by co-precipitation process. The influence of the addition of 1.7 mol% Y2O3 in Mg- PSZ on its microstructure and mechanical properties was investigated. Precursor powders were ground into a high energy grinder mill for 4 h, uniaxially pressed (98 Mpa) into pellets with 10 mm diameter and thickness and sintered at 1,500 °C for 1 h. Mechanical properties were evaluated by Vickers indentation technique. The microstructure has been examined by SEM (scanning electron microscopy) and the crystalline phases were analyzed by XRD (X-ray diffraction). Dense ceramics (99% of theoretical) were obtained, after sintering.