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 gra...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℃in water.The samples sintered at 1300℃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.展开更多
基金financially supported by the Foundation of Hubei Province Key Laboratory of Green Materials for Light Industry,Hubei University of Technology。
文摘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℃in water.The samples sintered at 1300℃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.
