Ceramics-Silikáty 44 (2) 41-47 (2000)

ALUMINA TOUGHENED ZIRCONIA MADE BY ROOM TEMPERATURE EXTRUSION OF CERAMIC PASTES

W. Pabst, J. Havrda, E. Gregorová, B. Krčmová 

A novel preparation route for ATZ (alumina toughened zirconia) ceramics is presented, using a commercial ATZ powder (a mixture of 20 wt.% alumina and 80 wt.% zirconia containing 3 mol.% yttria) as a solid filler and an ATZ sol or gel (of the same composition) as a liquid binder for paste extrusion at room temperature. The pastes have a total oxide content of approx. 70 wt.% and during heat treatment the binder composition accommodates to the composition of the filler powder. Extruded samples are characterized before and after heat treatment by determining their shrinkage, bulk density, apparent density and apparent porosity. The optimal firing temperature is determined to be about 1550 °C. Quantitative X-ray phase analysis is used to establish the phase composition (ratio of monoclinic to tetragonal zirconia) and to calculate a (spatially averaged) mean value for the true density of the prepared nanocomposite after firing, which is 5.45 g cm^-3. For optimally sintered specimens the bulk density is approx. 5.06 g cm^-3, i.e. 92.8 % of the theoretical value. The total porosity after sintering is approx. 6.8 % (open 4.7 %, closed 2.1 %).