Fabrication, microstructure, and properties of 8 mol% yttria-stabilized zirconia (8YSZ) transparent ceramics

Fine grained 8 mol% yttria-stabilized zirconia (8YSZ) transparent ceramics with high optical and mechanical properties were fabricated by air pre-sintering and hot isostatic pressing (HIP) using commercial 8YSZ powders as the raw material. The pre-sintered ceramics with fine grains and appropriate relative density play a key role to achieve high transparency and suppressed grain size after HIP post-treatment at relatively low temperatures. With the increase of HIP temperature from 1350 to 1550 °C, the in-line transmittance of 8YSZ ceramics at 600 nm increases from 56.9% to 71.5% (2.5 mm in thickness), and the average grain size increases from 2.4 to 16.3 µm. The corresponding bending strength of 8YSZ transparent ceramics decreases from 328±20 to 289±19 MPa, the hardness ( H ) decreases from 12.9±0.1 to 12.5±0.2 GPa, and the fracture toughness ( K IC ) decreases from 1.30±0.02 to 1.26±0.03 MPa·m 1/2 . Systematical investigations were carried out to study the combination of high optical transparency and excellent mechanical properties in 8YSZ ceramics.