Effect of titania addition on yttria-stabilised tetragonal zirconia ceramics sintered at high temperatures

In order to combine the mechanical properties of yttria-stabilised zirconia (ZrO2–3 mol% Y2O3; code Y–ZrO2) with the bioactivity of titania (TiO2), Y–ZrO2–TiO2 green compacts with 0–40 vol.% TiO2 were sintered at 1300, 1400, and 1500 °C for 4 h, respectively. The microstructural features such as grains, pores, and phases were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDX). The mechanical properties such as hardness and toughness were also determined using the methods of Vickers indentation and Knoop indentation. All the composites showed the major tetragonal Y–ZrO2 phase regardless of the content of the added TiO2. However, rutile TiO2 phase was obtained at 1300 °C, whereas zirconium titanate (ZrTiO4) phase was found at 1400 and 1500 °C. The Y–ZrO2–ZrTiO4 composites sintered at 1500 °C showed relatively high hardness (860–1000 kg/mm2) and toughness (4.0–4.5 MPa m0.5), whereas the Y–ZrO2–TiO2 composites sintered at 1300 °C had slightly lower hardness (720–950 kg/mm2) and fracture toughness (3.1–3.3 MPa m0.5).