Microstructure and mechanical properties of ZrO₂-40 wt%Al₂O₃ composite ceramics

The effects of the sintering temperature on the microstructure, crystalline phases and mechanical properties 3 mol% yttria-stabilized ZrO₂-40 wt.% Al₂O₃ (abridged as 3YSZ-40 wt.% Al₂O₃) composites has been investigated. The monoclinic Zirconia (m-ZrO₂) phase has completely been transformed into tetragonal zirconia (t-ZrO₂) phase for Al₂O₃ content. The presence of 3 mol% yttria-stabilized zirconia (3YSZ) particles on the grain boundaries effectively limits a rapid grain growth of the Al₂O₃ grains. The relative density and average grain size increased with increasing the sintering temperature. The maximum flexural strength of 395 MPa, Vickers hardness of 15.01 GPa and fracture toughness of 6.1 MPa·m^1/2 was associated with the highly 99.4% dense homogeneous microstructure consisting of t-ZrO₂ grains of the critical size, which makes it suitable for dental applications.