Sintering mechanisms of partially stabilized zirconia (TZ3Y) with ZnO and Co<sub>3</sub>O<sub>4</sub> as sintering additives

Marcomini, R. F.; Arantes, V. L.

doi:10.1590/0366-69132021673823099

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Articles • Cerâmica 67 (382) • Apr-Jun 2021 • https://doi.org/10.1590/0366-69132021673823099 copy

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

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

In this work, the sintering mechanisms of 3 mol% yttria-stabilized zirconia (TZ3Y) and TZ3Y containing 0.3 wt% of ZnO or Co₃O₄ 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 Co₃O₄ additive acted via solid-state sintering by increasing cation diffusivity.

Keywords:
sintering additives; sintering mechanism; zirconia; ZnO; Co₃O₄

Relative density	A₀ (K/s)	E/R (K)	r²
TZ3Y
0.600	5.11x10¹⁹	6.68x10⁴	0.988
0.625	6.47x10¹⁷	6.13x10⁴	1.000
0.650	2.92x10¹⁶	6.07x10⁴	0.984
0.700	6.72x10¹⁶	5.93x10⁴	0.968
0.750	1.94x10¹⁵	5.47x10⁴	0.946
0.800	3.11x10¹³	4.91x10⁴	0.915
0.850	1.27x10¹⁰	3.77x10⁴	0.796
TZ3Y+0.3 wt% ZnO
0.600	7.34x10¹⁹	6.46x10⁴	0.996
0.625	3.07x10²¹	7.09x10⁴	0.999
0.650	1.94x10²⁴	8.11x10⁴	0.999
0.700	2.07x10²⁵	8.65x10⁴	0.996
0.750	4.25x10²³	8.24x10⁴	0.992
0.800	2.73x10²²	7.97x10⁴	0.986
0.850	2.37x10²⁰	7.38x10⁴	0.991
TZ3Y+0.3 wt% Co₃O₄
0.600	4.61x10²³	7.56x10⁴	0.908
0.625	5.37x10²³	7.70x10⁴	0.938
0.650	5.35x10²²	7.47x10⁴	0.934
0.675	1.49x10²²	7.35x10⁴	0.943
0.700	1.16x10²²	6.91x10⁴	0.948
0.750	4.49x10²⁰	6.99x10⁴	0.977
0.800	6.92x10²⁶	9.24x10⁴	0.880

Material	Sintering additive	Relative density	Activation energy (kJ/mol)	Ref.
TZ3Y	N/A	60%	555	This work
		70%	493
		80%	313
TZ3Y	0.3 wt% ZnO (0.46 mol% ZnO)	60%	537	This work
		70%	718
		80%	662
TZ3Y	0.3 wt% Co₃O₄ (0.16 mol% Co₃O₄)	60%	628	This work
		70%	574
		80%	768
TZ3Y	N/A	73%	935	⁹9 G. Bernard-Granger, C. Guizard, J. Am. Ceram. Soc. 90, 4 (2007) 1246.
TZ3Y	N/A	90%	310
TZ8Y	N/A	<56%	691	¹¹11 X.C. Song, J. Lu, T.S. Zhang, J. Ma, J. Eur. Ceram. Soc. 31, 14 (2011) 2621.
TZ8Y	N/A	>56%	572
TZ8Y	0.5 mol% NiO	<56%	660	¹¹11 X.C. Song, J. Lu, T.S. Zhang, J. Ma, J. Eur. Ceram. Soc. 31, 14 (2011) 2621.
TZ8Y	0.5 mol% NiO	>56%	501
TZ8Y	N/A	Initial stage	1087	⁵5 T. Selvaraj, B. Johar, S.F. Khor, Mater. Chem. Phys. 222 (2019) 309.
TZ8Y	N/A	Intermediate stage	318
TZ8Y	0.5 mol% Fe₂O₃ + 2.5 mol% ZnO	Initial stage	283	⁵5 T. Selvaraj, B. Johar, S.F. Khor, Mater. Chem. Phys. 222 (2019) 309.
TZ8Y	0.5 mol% Fe₂O₃ + 2.5 mol% ZnO	Intermediate stage	145
TZ8Y	1.0 mol% Fe₂O₃ + 2.0 mol% ZnO	Initial stage	279	⁵5 T. Selvaraj, B. Johar, S.F. Khor, Mater. Chem. Phys. 222 (2019) 309.
TZ8Y	1.0 mol% Fe₂O₃ + 2.0 mol% ZnO	Intermediate stage	144
TZ8Y	1.5 mol% Fe₂O₃ + 1.5 mol% ZnO	Initial stage	264	⁵5 T. Selvaraj, B. Johar, S.F. Khor, Mater. Chem. Phys. 222 (2019) 309.
TZ8Y	1.5 mol% Fe₂O₃ + 1.5 mol% ZnO	Intermediate stage	143
TZ8Y	2.0 mol% Fe₂O₃ + 1.0 mol% ZnO	Initial stage	579	⁵5 T. Selvaraj, B. Johar, S.F. Khor, Mater. Chem. Phys. 222 (2019) 309.
TZ8Y	2.0 mol% Fe₂O₃ + 1.0 mol% ZnO	Intermediate stage	197
TZ8Y	2.5 mol% Fe₂O₃ + 0.5 mol% ZnO	Initial stage	544	⁵5 T. Selvaraj, B. Johar, S.F. Khor, Mater. Chem. Phys. 222 (2019) 309.
TZ8Y	2.5 mol% Fe₂O₃ + 0.5 mol% ZnO	Intermediate stage	190

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

Abstract

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