Sintering mechanisms of partially stabilized zirconia (TZ3Y) with ZnO and Co3O4 as sintering additives

Abstract

In this work, the sintering mechanisms of 3 mol% yttria-stabilized zirconia (TZ3Y) and TZ3Y containing 0.3 wt% of ZnO or Co 3 O 4 were analyzed by determining the apparent activation energy of sintering from dilatometry data and observing the evolution of microstructure. Dilatometry test was performed at a heating rate ranging from 5 to 20 °C/min from room temperature up to 1500 °C. The main mechanism of each sintering additive for the studied samples was revealed from the variation of the sintering activation energy as a function of the relative density and scanning electron microscopy images. The mechanism for the ZnO additive was the formation of a liquid phase at the beginning of the sintering process, while the Co 3 O 4 additive acted via solid-state sintering by increasing cation diffusivity.

Sintering activation energies of anisotropic layered and particle alumina/zirconia-based composites and their mechanical response

“…It was found that activation energies of nominally pure alumina and zirconia were 670 and 580 kJ/mol in longitudinal orientation and 700 and 550 kJ/mol in transversal orientation, respectively. These values fit the previously reported data in the literature covering a big scatter in the range of 342 -1163 kJ/mol for alumina [1-4, 7-13, 21, 22, 51] and 310 -990 kJ/mol for zirconia [3,9,[14][15][16]22]. The broad values spread is given by evaluation method, morphology [7] and purity of the powder used, considered density interval [14,52,53], different microstructure before sintering and temperature range [9].…”

“…A lot of works have been published up to now to establish activation energies of nominally monolithic ceramics. The most attention was paid to alumina [1][2][3][7][8][9][10][11][12][13], zirconia [3,7,9,[14][15][16], silicon nitride [17], zinc oxide [8], uranium dioxide [18,19], yttrium oxide [20], etc. Moreover, it was found that the sintering technique can also play a role in diffusion mechanisms in studied materials affecting the activation energy of sintering [8].…”