Effect of titania and magnesia addition to 3 mol% yttria doped tetragonal zirconia on some diffusion related phenomena

The 3 mol% yttria doped tetragonal zirconia (3YTZ) is known to show ionic conductivity and superplastic property. However, the application of superplasticity to the manufacturing process is limited because the strain rate is low. The purpose of this study is to fabricate high-strain rate superplastic zirconias by adding titania and magnesia to 3YTZ. Effect of titania and magnesia addition to 3YTZ on diffusion related phenomena such as sintering, grain growth, superplastic properties and ionic conductivity was investigated. Dense and fine-grained zirconia polycrystals were obtained by colloidal processing, where aqueous suspensions were prepared by dispersing 3YTZ, magnesia and titania powders by ultrasonication and adding the appropriate amount of polyelectrolyte. The grain growth was controlled by cation lattice diffusion and the grain growth rate was enhanced by adding titania and magnesia. The tensile ductility of about 216% was established for the titania and magnesia added 3YTZ at the low temperature of 1350 °C and high strain rate of 1.2×10−2 s−1. The ionic conductivity of 3YTZ was decreased with titania addition.