DISPERSIVITY AND PHASE COMPOSITION
OF ZIRCONIA-BASED POWDERS
Yu. N. Vil’k
Translated from Ogneupory i Tekhnicheskaya Keramika, No. 7, pp. 22 – 26, July, 2001.
Results of an electron microscopic and x-ray diffraction study and data on dispersivity (obtained using a
microanalyzer) and density (obtained using a helium pycnometer) of powders in the ZrO
containing 93.54 – 100 wt.% ZrO
are presented. The powders are prepared by a chemical co-precipitation
method. Crystalline and morphological structural features of powder particles are considered and compared to
those of powder particles of close composition obtained by a plasma-assisted chemical method. Effects of
morphology and structure of the particles on the processability of powders are discussed.
Powders, mainly based on ZrO
and produced by indus-
trial or semi-industrial technologies, are used as components
of a wide range of refractory and structural materials. The
dispersivity and phase composition of powders are factors
essential for the technological properties of commercial
components, and knowledge of these characteristics has im-
portant practical implications.
In this paper, results of electron microscopic and x-ray
phase studies of ZrO
-based powders obtained by the method
of chemical co-precipitation are presented. Dispersivity data
of these powders obtained by means of a “Mastersizer Micro
Microplus,” Serial No. 33091 Software Version 2.1 laser
analyzer (Malvern Instruments Ltd.) are also given.
Scanning electron microscopy (SEM) and transmission
electron microscopy (TEM) were used to determine the
shape and size of microparticles and conglomerates and the
phase composition of crystalline microparticles from an
analysis of diffraction microimages.
Methods for preparing specimens for SEM and TEM
studies and determining the average size of macro- and
microparticles have been described elsewhere [1 – 3]. Re
sults relevant to the present study are given in Table 1.
The shape and size of conglomerates as measured by
SEM are shown in Fig. 1.
Powder No. 1 studied here, when compared to powder
No. 1 in , shows a lesser degree of agglomeration, and its
particles are irregular (fragmental), rather than globular, in
shape and markedly different in size (from 1.0 to 22.0 mm).
Powder No. 1, when ground in a planetary mill, produced a
material with particles (conglomerates) of still smaller size
(minimum 0.6 and maximum 12.0 mm), mostly fragmental in
shape (powder No. 2). Powder No. 3 has particles of smaller
size, mostly of irregular (indistinct) shape; the powder parti-
cles are agglomerated. The particles of powder No. 4 are also
indistinct in shape and likewise agglomerated. When ground
in a planetary mill, the powder particles became reduced in
size (powder No. 5) and developed a more uniform size dis
The SEM photomicrographs of powders Nos.1–5 are
shown in Figs. 2 – 4. By use of a technique analogous to that
of , the shape and size of particles (components of ag
glomerates) and their phase composition (by diffraction
micropatterns) were determined. Relevant data are given in
The micrographs in Figs. 2 and 4 show that the powders
in question bear a resemblance to those described in  and
represent an assemblage of microparticles embedded in an
amorphous matrix. The microparticles are mainly globular in
shape, without clearly marked crystalline features. They are
combined into micro and macroconglomerates. The powder
particles in question are about twice as small as those re
ported in .
A petrographic analysis showed that powders Nos. 1 and
2 consist of colorless isotropic or pseudoisotropic grains of
irregular, angular shape, with a refractory index from 1.598
to 1.720. Mostly, it was N ~ (1.598 ± 0.003) – (1.610 ± 0.003).
The size of grains (agglomerates) varied from 1 to 40 mm.
Occasionally, grains (agglomerates) as large as 80 – 100 mm
Refractories and Industrial Ceramics Vol. 42, Nos.7–8, 2001
1083-4877/01/0708-0280$25.00 © 2001 Plenum Publishing Corporation
Central Research Institute for Materials (TsNIIM), St. Petersburg,