MODIFICATION OF HCBS AT THE NANODISPERSION LEVEL
E. A. Doroganov
and A. V. Mazurov
Translated from Novye Ogneupory, No. 10, pp. 30 – 34, October 2010.
Original article submitted October 1, 2009.
The possibility of modifying HCBS by artificial introduction of an optimum amount of nanoparticles in the
form of silicic acid gel is studied. It is shown that a modifying addition promotes improvement of rheo
technological properties of suspensions, and an increase in the physicomechanical properties of castings based
Keywords: HCBS, modification, strengthening by UKhAKS (chemical activation of contact bonds) method.
As is well known, the properties of highly concentrated
ceramic binder suspensions (HCBS) are considerably af-
fected by the content of nanoparticles (colloidal component)
in the original system, i.e., the finely dispersed fraction of the
HCBS solid phase . Nanoparticles in the stage of HCBS
preparation and molding systems promote achievement of
the optimum rheotechnological properties, in the stage of
structure formation and drying they determine the increase in
mechanical strength, and in the warm-up (firing) stage they
determine a marked increase in strength at 800 – 1000°C .
The fraction of HCBS nanoparticles has a complex com-
position, since it includes not only residue of the basic solid
phase, but also grinding products of milling bodies or impu
rities passing into a dispersed medium during dissolution of
the surface of grindable particles. Within the composition of
an HCBS colloidal component there are also residues of ad
ditions of water glass or other electrolytes, introduced for
controlling rheological and binder properties. The colloidal
component of an HCBS is represented by sols and particles
of sub-colloidal size .
Studies have been made previously [3, 4] for the effect of
colloidal component (nanoparticles) on different properties
of both HCBS and materials based on them. The original
HCBS are impoverished or enriched in colloidal compo
nents, prepared by ultracentrifuging or within the composi
tion of HCBS of very fine quartz glass added to the HCBS
composition. It has been shown that the optimum content of
nanoparticles is a favorable factor in HCBS technology and
In preparing materials with use as HCBS as a binder, as a
rule there is a problem of preparing material within which
the matrix phase has a high density (low porosity). The po-
rosity of the matrix phase is a complex function of HCBS
production and rheological properties, dispersion character-
istics and material molding conditions. One of the main fac-
tors for reducing porosity of a semifinished product, molded
by different methods, is the choice of optimum grain size
composition. The HCBS composition may be controlled at
different levels of dispersion: at the microlevel (1 – 200 mm)
with introduction of filler; at the mesolevel (0.1 – 5 mm) with
controlled grinding, with introduction of filler; at the
nanolevel (less than 0.1 mm) with controlled grinding, and
with introduction of different modifying additions.
In view of the fact that during grinding and stabilization
it is not always possible to obtain HCBS with the optimum
content of colloidal component, we have attempted to mod
ify HCBS by artificial introduction of an additional amount
of nanoparticles and to study the effect on the main
physicomechanical properties of both the HCBS and ceramic
concretes based upon it. The starting material was high-alu
mina chamotte (not less than 72% Al
), which is used for
preparing HCBS and as a filler during concrete manufacture.
The modifying addition (MA) used was anhydrous silicic
(chemically pure reagent) and synthesized silica
gel, obtained as a result of chemical reaction of sodium water
glass and hydrochloric acid followed by washing out NaCl.
Use of modifying additions, containing SiO
, is connected
with the fact that in this system there is an effect of low-tem
perature mullite formation and improvement of thermo
mechanical properties .
A highly concentrated binder suspension was prepared
by wet grinding in a ball mill with a volume of 200 liters by
Refractories and Industrial Ceramics Vol. 51, No. 5, January, 2011
1083-4877/11/5105-0366 © 2011 Springer Science+Business Media, Inc.
V. G. Shukhov Belgorod State Technological University, Belgo