Sintering and densification behavior of ZnO-doped Y-TZP ceramics

Abstract

The effect on densification and mechanical properties of 3 mol Y-TZP ceramics doped with zinc oxide (0.1 wt. to 1 wt.), has been investigated in this study. Green samples were compacted by uniaxial pressing and cold isostatically pressed at 200 MPa. All samples have been sintered over the temperature range of 1250 degrees C to 1500 degrees C with a ramp rate of 10 degrees C/ minute and 2 hours of holding time. In addition to that, the tetragonal phase stability of the samples was also studied in superheated steam at 180 degrees C/10 bar for up to 50 h. The sintered bodies were examined to determine the phase content, bulk density, Young's modulus, Vickers hardness and fracture toughness. The results showed that the addition of 1 wt. ZnO was effective in aiding densification (similar to 99 theoretical density). It also improved the matrix stiffness (similar to 208 GPa) and Vickers hardness (similar to 13 GPa), when the samples were sintered below 1300 degrees C comparing to the undoped Y-TZP sintered at the same temperature. In contrast, ZnO addition to the Y-TZP matrix displayed a tendency to change hydrothermal ageing behavior as it was noticed that the monoclinic content increased with increasing content of dopant. The undoped samples showed a better hydrothermal ageing behavior at 1300 degrees C compared to the doped samples