Preparation of Fine-grained 3Y-TZP Ceramics with Enhanced Low-temperature Degradation Resistance

Abstract

The occurrence of tetragonal to monoclinic phase (t→m) transformation in zirconia ceramics under humid ambient conditions induces the low-temperature degradation (LTD). Such t→m transformation could be suppressed by grain size refinement or/and doping small amounts of alumina. Fine-grained dense 3mol% yttria-doped tetragonal zirconia polycrystal (3Y-TZP) ceramics were prepared by pressureless sintering a zirconia powder doped with 0.25wt% alumina. The LTD behaviors of as-prepared 3Y-TZP ceramics were evaluated by accelerated aging at 134 °C in water. The samples sintered at 1 300 °C for 2 h achieve the relative density higher than 99.9% with the average grain size of 147 nm. The 3Y-TZP ceramic exhibits excellent LTD resistance that no t→m transformation takes place after 125 h accelerated aging. Large amounts of defects were observed inside grains evidenced by the high-resolution transmission electron microscopic (HRTEM) analysis. It is proposed that the presence of defects enhances the sintering kinetics and favors the present low-temperature densification. Possible reasons for defects formation were discussed and the mechanical properties of the 3Y-TZP ceramic were reported as well.

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Wuhan University of Technology and Springer-Verlag GmbH Germany, Part of Springer Nature