PRODUCTION AND EQUIPMENT
PHENOMENON OF AN ELASTIC AFTER-EFFECT WITH QUASI-ISOSTATIC
COMPACTION AND COMPACT DEFECTS
M. I. Timokhova
Translated from Novye Ogneupory, No. 10, pp. 17 – 23, October 2008.
Original article submitted June 18, 2008.
The phenomenon of an elastic after-effect for compacted elastic elements and the reasons for compacted ob
ject failure are considered. Recommendations are made for avoiding defects in compacted objects. Use of an
anti-breaking device in mold construction provides preparation of objects with a density close to theoretical
over a wide range of compaction pressure.
In recent years in developing an isostatic compaction
method a volumetric method has been developed for com-
pacting pressed material, i.e. quasi-isostatic compaction,
combining the advantages of static and hydrostatic methods
of pressing. Pressing is accomplished without use of isostats
in a quasi-isostatic compaction mold similar in construction
to normal metallurgical molds using pressing equipment em-
ployed for static compaction. As a pressing medium, trans-
ferring the force of the press to the pressed material, elasto-
mers are used providing preparation of high quality objects
as a result of creating volumetrically uniform compression of
pressed material in any zone of the mold.
In contrast to the method of hydrostatic pressing  the
method of quasi-isostatic compaction has found extensive
use in plants producing series products due to its simplicity,
economically high productivity, a reduction in capital expen
diture, a reduction in production area, a reduction of the time
of assimilation under production conditions, since there is no
requirement for acquiring special equipment, and also as a
result of the real possibility of the manufacture of molds in
factories by their own efforts.
The method of quasi-isostatic compaction is amenable to
total mechanization and automation. It is suitable for mold
ing objects of plastic non-plastic materials: saggers and cas
ings of circular, rectangular and square shape. Operation of
saggers, prepared by this technology, has shown an increase
in their turnover by a factor of five to seven.
The ultrahigh specifications laid down for vacuum-tight
rings, used in the electronic industry, for vacuum tightness
and physicomechanical properties could not be provided in
our country by any of the ceramic technologies existing in
this field. In view of the stringent requirement for these ob-
jects one of the enterprises of the electronic industry con-
cluded an agreement for the supply of one type of object
from an overseas firm, Siemens. Molding of objects was in-
tended by the hydrostatic compaction method. However, the
firm did not manage to provide the required quality of vac-
uum-tight rings by the hydrostatic compaction method, and it
was necessary to pay a penalty.
In order to provide the quality required for these objects
it was necessary to develop a new production process, i.e.
volumetric compaction, that made it possible to provide the
same uniform density at any point of an object. Introduction
of the technology of volumetric (quasi-isostatic) compaction
in factories producing series products entirely provided the
requirements of enterprises of the electronic technology for
high quality objects and it made it possible to create a num
ber of instruments markedly exceeding in operating capacity
the level of the best overseas analogs. Vacuum-tight rings
have a uniform structure and density close to theoretical, in
any cross section of an object, with high physicomechanical
and electrical properties, and a high output of finished ob
jects. For rings with a diameter of 300 and a thickness of
205 mm and weighing 106 kg the output of finished fired ob
jects taking account of the operation of all-round grinding
during 10 years was not less than 65%, and mainly reaching
90%, whereas with use of hot casting technology under pres
sure in order to prepare objects of the same diameter but less
thick and weighing three times less, the output of finished
products was 8 – 10%. The compaction process for these
Refractories and Industrial Ceramics Vol. 49, No. 6, 2008
1083-4877/08/4906-0426 © 2008 Springer Science+Business Media, Inc.