Effect of magnesium oxide on the microstructure and mechanical properties of yttria-stabilized zirconia-based ceramics

In the present work, sintering and investigation of composite ceramic materials based on nanostructured MgO–ZrO 2 powders were carried out. Zirconium dioxide was additionally stabilized with 3 mol. % yttrium oxide. The nanopowders were pre-treated by mechanical activation using a planetary ball mill at a rotation frequency of 10 Hz. Zirconium dioxide balls were used as the grinding media. The prepared powders were compacted at pressing pressures of 50, 100, 200, and 300 MPa. The compacts were sintered in a high-temperature furnace at 1700 °C. Microstructural studies were performed on the polished surfaces of the sintered samples using scanning electron microscopy (SEM). EDX mapping was conducted to determine the elemental distribution, confirming the presence of two phases in all samples. To evaluate the effectiveness of stabilizing additives on the polymorphic transformation of zirconium dioxide, X -ray diffraction (XRD) analysis was performed. The porosity of the materials and its dependence on the pressing pressure and magnesium oxide content were also assessed. Mechanical properties such as Martens hardness and elastic modulus were measured using a NanoIndenter G200, while flexural strength was evaluated by scratch testing on the same device. Fracture toughness was determined by the indentation method using the Marshall–Evans approach. The influence of magnesium oxide additives on the physical and mechanical properties of the MgO–ZrO 2 composite ceramics was established.