SCIENTIFIC RESEARCH AND DEVELOPMENT
POWDER COMPACT STRUCTURE.
PART 1. PARTICLE PACKING INHOMOGENEITY
A. V. Galakhov
Translated from Novye Ogneupory, No. 5, pp. 22 – 32, May, 2014.
Original article submitted March 14, 2014.
Powder compact characteristics, on which its sintering kinetics, grain formation, and structural oxide ceramic
mechanical properties depend, are considered. Powder compact inhomogeneity criteria are formulated. Rea
sons are analyzed for forming pore space structure inhomogeneity. Experimental data are provided for the ef
fect of powder compact structure inhomogeneity on compaction kinetics and grain growth within it during
Keywords: powder compact, inhomogeneity, structure, structural oxide ceramic, sintering, compaction kinet-
ics, grain growth.
Mechanical properties are particularly important for ce-
ramics for structural purposes. Use of powders with particles
of submicron size makes it possible to intensify sintering,
and to facilitate preparation of material with a fine grain
structure and good physicomechanical properties. However,
in spite theoretical predictions for compacts made from
submicron powders after sintering, a suitable density is often
not achieved, there are coarse residual pores and other de
fects, which worsen material properties. A more detailed
study of ultrafine powders has shown that such a system
should not be considered as a simple collection of individual
particles. The finest individual particles are often collected
into well-formed agglomerates, sometimes stably sintering
groups of particles, have been given the name agglomerates.
The agglomeration capacity of ultrafine powders generates
extreme pore space inhomogeneity in powder compacts
formed from them. A coarse grained structure is achieved in
sintered material, inherited from a compact inhomogeneous
pore structure, not facilitating development of good mechan
ical properties. In view of these reasons a study of features of
the effect of powder compact pore characteristics on
sintering and structure within sintered material is an impor
tant task, whose solution will facilitate an improvement in
the efficiency of structural ceramic technology.
POWDER COMPACT STRUCTURE
INHOMOGENEITY EVALUATION CRITERIA
In appearance the problem considered in this publication
conveniently defines a powder compact as a collection of
powder particles in contact with spaces between them. Terms
often used for a pore space are; interparticle cavities, poros
ity, and pore space. The last term is used most often. Prop
erties of particles in contact and their mutual position are
mainly determined by pore space geometry. This geometry,
as is shown subsequently, has a considerable effect on occur
rence of powder compaction during sintering, sintered mate
rial structure, and consequently on its mechanical properties.
Geometric properties of a pore space are not numerous,
but at the same time a collection in a significant way, often
definitive, affects the course of physical processes occurring
within it. In production practice compact quality is often
evaluated by one parameter, i.e., density. However, one char
acteristic is not always sufficient. Pore size distribution is
used for more precise evaluation of pore space geometry.
This property contains information about the distribution of
discrete cavity dimensions within a powder compact, desig
nated by the concept of a “pore”. The number of experimen
Refractories and Industrial Ceramics Vol. 55, No. 3, September, 2014
1083-4877/14/05503-0199 © 2014 Springer Science+Business Media New York
FGBUN A. A. Baikov Institute of Metallurgy and Materials Sci
ence, Russian Academy of Sciences, Moscow, Russia; e-mail: