Non-agglomerated Nanoparticles Research Articles

Processing of nanostructured zirconia ceramics

The inert gas condensation (IGC) technique was employed to synthesize nonagglomerated nanoparticles of ZrO 2 and Y 2O 3 with different average particle sizes ranging from 4 to 14 nm. High pressure phases were found in the as-prepared powders of both n-Y 2O 3 and n-ZrO 2. This has been explained on the basis of Gibbs-Thomson effect. The sintering behaviors (in air and vacuum) of single phase n-ZrO 2 (monoclinic crystal structure) and Y 2O 3-ZrO 2 mixture (Y-TZP) were studied in terms of densification rate and final sintering temperature. There was a strong correlation between densification characteristics and properties of the starting powder compacts, such as average particle size, particle and pore size distributions. n-ZrO 2 was sintered to full density in air at temperatures as low as 1125 °C (0.47 T m) and in vacuum at 975 °C (0.42 T m). Although the grain sizes in the fully sintered samples were well below 100 nm, the grains had grown by a factor of at least 10, as compared to the initial particle size. Therefore, pressure-assisted sintering techniques, such as sinter-forging and hot pressing, were employed to further reduce the densification temperature and final grain size. Threshold effects in these processes are also discussed.

Processing of Nanostructured Zirconia Ceramics

ABSTRACTThe inert gas condensation (IGC) technique was employed to synthesize non-agglomerated nanoparticles of ZrO2 and Y2O3 with different average particle sizes ranging from 4 to 14 run. The sintering behaviors (in air and vacuum) of single phase n-ZrO2 (monoclinic crystal structure) and Y2O3-ZrO2 mixture (Y-TZP) were studied in terms of densification rate and final sintering temperature. There was a strong correlation between densification characteristics and properties of the starting powder compacts such as average particle size, particle and pore size distributions. n-ZrO2 was sintered to full density in air at temperatures as low as 1125°C (0.47 Tm) and in vacuum at 975 °C (0.42 Tm). Although the grain sizes in the fully sintered samples were well below 100 nm, the grains had grown by a factor of 10 as compared to the initial particle size. Therefore, a pressureassisted sintering technique was employed to further reduce the densification temperature and final grain size. Threshold effects in this process are also discussed.