Properties of Y-TZP/Al2O3 ceramic nanocomposites obtained by high-energy ball milling

In this work, the synthesis of Y2O3 stabilized tetragonal zirconia polycrystals (Y-TZP)-alumina (Al2O3) powder mixture was performed by high-energy ball milling and the sintering behavior of this composite was investigated. In order to understand the phase transformations occurring during ball milling, samples were collected after different milling times, from 1 to 60 h. The milled powders were compacted by cold uniaxial pressing and sintered at 1400 and 1600 °C. Both powders and sintered samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry analysis (EDS) and mechanical properties. Fully dense samples were obtained after sintering at 1600 °C, while the samples sintered at 1400 °C presented a full density for powder mixtures milled for 30 and 60 h. Fracture toughness and Vickers hardness values of the Y-TZP/Al2O3 nanocomposite were improved due to dispersed Al2O3 grains and reduced ZrO2 grain size. Samples sintered at 1400 °C, based on powders milled for 60 h, presented high KIC and hardness values near to 8.0 MPam1/2 and 15 GPa, respectively.