Low-temperature sintering and microstructural development of nanocrystalline Y-TZP powders

Powders of yttria-doped tetragonal zirconia (3 mol%) with a narrow pore size distribution and ultrafine particle size (similar to 9 nm) have been prepared by the mixed organic + inorganic precursors coprecipitation method The compaction behaviour of almost agglomerate-free calcined powders was studied, and their sintering behaviour using both isothermal and non-isothermal techniques was evaluated. Fully dense nanoscale ceramics with. an average grain size below 95 nm were obtained after sintering at 1200 degrees C for 20 min or at 1150 degrees C for 4 h. Several stages were identified in the whole densification process: it was found that a particle rearrangement process assisted by sintering pressure is the densification mechanism in the earlier sintering step (up to 800 degrees C), and grain boundary diffusion was the dominant mechanism for densification up to 1180 degrees C. Activation energy values of 130 +/- 20 and 300 +/- 40 kJ mol(-1), respectively, were calculated for these densification mechanisms. The almost complete absence of agglomerates in the calcined powders and the homogeneous pore structure of the green compacts are the two main factors leading to low-temperature fully densified Y-TZP bodies. (C) 1996 Elsevier Science Limited.