POWDER COMPACT STRUCTURE.
PART 2. METHODS FOR INCREASING PARTICLE PACKING UNIFORMITY
A. V. Galakhov
Translated from Novye Ogneupory, No. 6, pp. 34 – 45, June, 2014.
Original article submitted March 14, 2014.
Methods are considered for increasing powder compact structure uniformity, conditionally classified as pro
cessing and structural. In considering processing methods main attention is devoted to an original approach
such as working a compact by deformation and two-stage sintering. Among structural methods those noted in
crease compact uniformity by organizing ordered structures of agglomerated powders and use of powders
with an internal nanostructure.
Keywords: powder compact, structure, uniformity, processing methods, structural methods.
All of the methods for improving powder compact ho-
mogeneity in structural ceramic technology may condition-
ally be sub-divided in two avenues. One of them is connected
with improvement of powder billet molding technology or
with performance of thermal, mechanical treatment for an al-
ready molded compact. This avenue is called processing.
Another avenue is connected with optimizing characteristics
of powder raw material used, and we call this avenue struc-
tural. It is understood that this classification does not pretend
to be rigid, and it is only for the purpose of organizing ac
counts into a sequence.
INCREASE IN PARTICLE PACKING
HOMOGENEITY BY PROCESSING METHODS
Improvement of processing methods for powder billet
molding is one of the definitive directions of ceramic tech
nology development. Good potential with respect to forming
a uniform structure is opened up by optimizing aggregation
and sedimentation stability of working suspensions in liq
uid-phase molding methods . A perceptible effect is also
use of all-round pressure molding method, i.e., the method of
isostatic pressing . These methods have general feature,
i.e., the powder compact structure formed in a molding oper
ation for a powder compact. These methods are connected
with optimizing molding technology and have been ade-
quately aired in numerous publications. Recently, the impor-
tance of new original standard methods for improving the
structure of a molded powder billet, not connected with its
molding, has acquired importance. Among them it is neces-
sary to note a method for developing a compact structure by
molding and a method for optimizing the porous structure of
a molded compact by two-stage sintering.
Compact structure development by deformation .
The main idea of this method involves the fact that a powder
compact prepared by any traditional molding method is then
subjected to action of intense shear deformation under condi
tions of all-round compression. A diagram of a device for de
forming a powder compact is shown in Fig. 1. A compact is
packed into a rubber shell, and placed within a chamber with
liquid between plates of a pressing unit. Pressure created
within the chamber is transferred to side surfaces of a com
pact through the elastic shell. Simultaneously the compact is
subject to uniaxial loading by the pressing plates. Under
these conditions a compact is “flattened” between plates. De
velopment of a compact structure achieved by this method is
by shear deformation without disrupting its continuity. In
tense shear deformation redistributes particles within it, forc
ing them to fill interagglomerate pores, reducing pore space
A method used for deforming compacts prepared by cast
ing from a liquid suspension is slip casting. Suspensions
have been prepared from aluminum oxide powders. One sus
pension contained strongly flocculated particles, i.e., in fu
Refractories and Industrial Ceramics Vol. 55, No. 3, September, 2014
1083-4877/14/05503-0209 © 2014 Springer Science+Business Media New York
Part 1 of the article published in Novye Ogneupory No. 5 (2014).
FGBUN A. A. Baikov Institute of Metallurgy and Materials Sci
ence, Russian Academy of Sciences, Moscow, Russia, e-mail: