PRESSURE-MOLDED HIGH-ALUMINA CERAMIC CASTABLES.
2. COMPACTION AND PROPERTIES OF MATERIALS BASED
ON PLASTICIZED BAUXITE HCBS, REACTIVE ALUMINA,
AND THEIR BINARY MIXTURES
Yu. E. Pivinskii,
Pavel V. Dyakin,
S. V. Vikhman,
and Petr V. Dyakin
Translated from Novye Ogneupory, No. 11, pp. 25 – 31, November, 2005.
Original article submitted March 14, 2005.
The effect of compacting pressure (20 – 100 MPa) on the densification of refractory clay plasticized molding
mixes based on bauxite HCBS containing 10% highly dispersed quartz glass, reactive STS-30 alumina, and
their binary compositions has been studied. The properties of these materials subjected to heat treatment are
discussed. Optimum compositions for binary systems are formulated that show promise as matrices for refrac
tory materials and for preparation of engineering ceramics.
The matrix in ceramic castables of corundum of high-
alumina composition may vary in Al
content. For this
reason, not only well-studied bauxite-based highly concen-
trated ceramic binding suspensions (HCBSs) with addition
of highly dispersed quartz glass (HDQG) , but also
HCBSs prepared from high-purity reactive alumina  or re-
lated binary systems, show promise for practical application.
In previous communication (Part I, ) an additional
component, GEF-grade alumina, was introduced to increase
the content of Al
in bauxite HCBS. The GEF alumina had
a lower degree of dispersion in comparison with the solid
phase of base HCBS (specific surface S
= 0.16 m
against 1.62). In this study, we have tested an STS-30-grade
reactive alumina (Alcoa) with 99.8% Al
= 3.8 m
and median diameter d
= 1.6 mm [2 – 4]. The specific sur
face of the bauxite HCBS solid phase (1.2 m
/g) was some
what less than that used in the previous work . Thus, in the
former case  the value of S
of the additional Al
ponent was 10 times less, and in the latter case, 3 times
greater as compared to the base HCBS (90% bauxite + 10%
highly dispersed quartz glass).
The integral grain-size distri
bution curves for the precursor systems (curves 1 and 2 ) and
their binary mixture (curve 3 ) are shown in Fig. 1. As can be
seen, in the STS-30-grade alumina the content of particles of
size < 1 mm is about 5 times less than in the base bauxite
HCBS. The value of d
in HCBS (6 mm) is nearly 4 times the
value of d
in alumina. The maximum particle size d
bauxite HCBS reaches 100 mm, whereas in alumina d
12 mm. The HCBS is rather low in ultrafine particles (0.1 –
0.3 mm), whereas alumina lacks them altogether. The poly
dispersity index K
for all the curves in Fig. 1 does not differ
significantly and ranges from 5.5 to 7.0.
Refractories and Industrial Ceramics Vol. 46, No. 6, 2005
1083-4877/05/4606-0396 © 2005 Springer Science+Business Media, Inc.
Kerambet Research and Development Firm, St. Petersburg, Rus
sia; St. Petersburg State Technological Institute (Technical Uni
versity), St. Petersburg, Russia.
In what follows, the initial mixes free of the additional alumina
are denoted as bauxite HCBS (all of them contain 10% HDQG).
100 10 1 0.1
Particle diameter, mm
Integral distribution, %
Fig. 1. Integral curves of particle size distribution for the solid
phase in bauxite HCBS (1 ), reactive STS-30-grade alumina (2 ), and
mixed HCBS with 20% STS-30 (3 ).