SCIENTIFIC RESEARCH AND DEVELOPMENTS
EFFICIENCY OF ADDING VERY FINE SILICA IN HIGH-SILICA
AND CORUNDUM CERAMIC CONCRETE TECHNOLOGY. PART 2
Yu. E. Pivinskii
and P. V. Dyakin
Translated from Novye Ogneupory, No. 3, pp. 34 – 40, March 2009.
Original article submitted September 22, 2008.
Results are provided for comparative evaluation of the properties of pressed specimens of a matrix system and
ceramic concrete specimens prepared on the basis of bauxite with very fine quartz glass and quartz sand
(VFQG and VFQS), and also the thermal expansion of castings based on a suspension of quartz sand, bauxite
and bauxite ceramic concrete. It is established that high-silica molded and unmolded ceramic concretes pre
pared on a basis of bauxite VFQG (85%) and VFQS (15%) have improved physicomechanical properties. Af
ter firing at 1150 and 1420°C their open porosity is 16 – 18% and the ultimate strength in compression is
95 – 125 MPa. Their temperature for the onset of softening is above 1570°C and higher than 1650°C (for com-
positions containing SiC).
Keywords: very fine silica, matrix system, ceramic concrete, bauxite suspension, open porosity, apparent
density, ultimate strength in compression, change in linear dimensions, weight content of matrix system, tem-
perature for the onset of softening, mullite formation.
As formulated previously , ceramic concretes are
considered as composite (heterogeneous) materials consist-
ing of a matrix or binder system (HCBS (highly concentrated
binding suspension) of an appropriate composition) and a re
fractory filler. It is conditionally assumed that the matrix ex
hibits the properties of continuity, but the filler has an inter
face. Here grains of filler only in a limited way (with a sur
face) react with the binder system. The matrix is condition
ally assumed to be homogeneous. It combines into a single
whole numerous polydispersed single particles, that give so
lidity and prescribed shape of an object or lining. The matrix
provides transfer of mechanical and thermal stresses to the
filler, and it may also partly prevent it from corrosive action
due to its fine capillary structure impermeable to melts
A considerable proportion of ceramic concretes in the
are currently produced using a matrix system based on baux
ite HCBS, containing VFQS (10 – 12%), in the form of
unmolded refractories, for example ramming mixes for
monolithic linings . The structure of these refractories is
formed directly during service. In addition, the area is ex-
panding for the use of molded refractories based on bauxite
HCBS that are subjected to prior firing at 1100 – 1430°C
[8, 9]. The authors of this article have studied a version of the
technology for molded refractories prepared by compaction.
According to this technology the original HCBS, having a
moisture content of about 12%, are mixed with a
polyfraction filler (densely sintered bauxite with a porosity
up to 5% or electrocorundum) and a plastifying addition is
made to the mixture obtained. Compaction is accomplished
in friction or hydraulic presses at a pressure P 15 – 200 MPa.
Depending on the type of filler used the refractories prepared
by this technology in accordance with the generally accepted
classification  relate to mullite corundum (for example
grade MKTP-85) or corundum (Al
> 90%) [3, 5, 8, 15].
COMPARATIVE EVALUATION OF POROSITY
AND STRENGTH OF MATERIALS
In part 1 of this articles there was comparative evaluation
of the properties of cast specimens of a matrix system pre
pared on the basis of mixed suspensions of bauxite with
VFQG or VFQS. In part 2 of this article there is not only
comparison of similar specimens with respect to composition
Refractories and Industrial Ceramics Vol. 50, No. 2, 2009
1083-4877/09/5002-0121 © 2009 Springer Science+Business Media, Inc.
Part 1 was published in Novye Ogneupory, No. 1 (2009).
OOO NVF Kerambet-Ogneupor, St. Petersburg, Russia.
St Petersburg State Technological Institute (Technical University).