PREPARATION AND PROPERTIES OF A CERAMIC
IN THE ZrO
L. V. Morozova,
A. E. Lapshin,
and V. B. Glushkova
Translated from Ogneupory i Tekhnicheskaya Keramika, No. 5, pp. 18 – 19, May, 2002.
solid solution (88 mol.% – 12 mol.%) is synthesized by coprecipitation. The effect of dry
mechanical grinding on the dispersity of the solid solution is studied. Combining methods of coprecipitation
and mechanical grinding intensifies the sintering process and allows preparation of compact ceramic materials
in the ZrO
Ceramics based on zirconium dioxide (zirconia) are
promising materials for multifunctional applications. Re-
cently, much attention has been focused on solid solutions of
tetragonal zirconia and cerium oxide. For synthesis of zirco-
nia-based ceramic composites, sol-gel technologies capable
of producing nanopowders (20 nm) are widely used [1 – 5].
A major disadvantage of these methods is that material
particles tend to form large agglomerates. A way toward re-
ducing the powder agglomeration in sol-gel technologies
consists of treating dry percursor powders in a planetary mill.
Thus treated, powders develop a higher loose density, a
higher compaction density during pressing, and better sinter
Our goal in this study was to see how the mechanical
treatment may affect the dispersivity and sinterability of a
solid solution (88 mol.% – 12 mol.%) obtained
by a coprecipitation method.
The powder of stabilized zirconia was prepared by a
backward precipitation method at pH = 9 from aqueous solu
tions of zirconium (about 0.2 M) and cerium (about 0.2 M)
nitrates. The precipitating agent used was an ammonium hy
droxide solution (about 0.1 M). The co-precipitate was
washed with distilled water, dried at 70°C, and heat-treated
at 300°C — conditions that are optimum for dehydration ac
cording to the results of a differential thermal analysis (car
ried out on a Netzsch derivatograph). An x-ray phase analy
sis (carried out on a D-500/HS diffractometer, Siemens)
showed that the precursor powder thus prepared is a
-based solid solution of pseudocubic structure.
An electron microscopic analysis (carried out on a
BS-300 scanning electron microscope) showed the powder
to consist of irregularly shaped agglomerates with a size of
5–7mm. Structurally, these agglomerates were clusters of
individual crystallites with an average size of 30 – 40 nm.
To reduce agglomeration, the powder was thoroughly
ground on a planetary mill (Fritsch), where the powder parti-
cles were subjected to the combined action of impact and
friction forces, with the dose of absorbed energy varying
from5to20kJ/mole. Grinding conducted for 15 min made
it possible to obtain a powder with a maximum particle size
of 2 mm and to reduce the size of individual crystallite to
20 nm. Results of an x-ray phase analysis showed that the
-based solid solution retained its pseudocubic structure.
The increase in heat-treatment temperature to 600°C
caused transition of the pseudocubic structure of the solid so
lution to a metastable tetragonal structure (t-ZrO
was seen in the splitting of a diffraction peak in the range
2q = 34 – 35 deg.
Heat treatment of the solid solution at 600 – 1400°C
caused precipitation of a monoclinic phase of zirconia
). The volume fraction of monoclinic and tetragonal
phases of the zirconia-based solid solutions was determined
using a formula proposed in  (Fig. 1).
The average size of crystallites in the tetragonal solid so
(88 mol.% – 12 mol.%) in the tempera
ture range 500 – 1400°C was evaluated from the broadening
of x-ray diffraction peaks using the Scherrer formula . The
growth of crystallite size from 25 to 200 nm as a function of
temperature is shown in Fig. 2.
The sintering process was studied on compact specimens
pressed at 150 MPa that were heated in a silicon-carbide rod
heating furnace at 1400°C for 2 h. It should be noted that
Refractories and Industrial Ceramics Vol. 43, Nos.5–6, 2002
1083-4877/02/0506-0179$27.00 © 2002 Plenum Publishing Corporation
This work was supported by the Russian Foundation for Basic
Research, grant No. 00-03–32192.
Institute of Silicate Chemistry, Russian Academy of Sciences, St.