Surface modification toughening of partially stabilized zirconia ceramics: by sub-eutectoid solution annealing

Abstract

In this investigation, surface modification toughening of partially stabilized zirconia ceramics, by sub-eutectoid solution annealing, has been performed. The Zr0.918Mg0.068Y0.014O1.925 designated (MZY) was prepared by mixing Magnesia Partially Stabilized Zirconia (MZ9) and Yttria Tetragonal Zirconia (TZ3Y) Polycrystal commercial powders using wet ball milling. The mechanical properties and microstructure of the MZY were investigated. XRD and SEM were used for phase analysis and microstructure examination of the sintered samples’ surfaces. The fracture toughness and hardness of the sintered compacts were determined by the Vickers indentation technique. The physical and mechanical properties of MZY were compared to those of MZ9 ceramics prepared under the same conditions. The results showed that, the Yttria addition inhibited the exaggerated growth of the tetragonal precipitates during sintering. The MZY showed a maximum in the fracture toughness of 12.9 MPa√m upon sub-eutectoid solution annealing at 1000 °C for 150 h, while the tetragonal precipitates in the MZ9 lost coherence due to their spontaneous massive transformation to the monoclinic phase via the decomposition reaction.