HIGH-TEMPERATURE SURFACE-ACTIVE SUBSTANCES
OF DIFFERENT COMPOSITION FOR USE IN REFRACTORY TECHNOLOGY
E. N. Demin,
A. V. Sarychev,
and S. I. Kazakov
Translated from Novye Ogneupory, No. 1, pp. 23 – 25, January, 2005.
Original article submitted December 8, 2004.
Results on the use of high-temperature SAS in the technology of alumomagnesian refractories are reported.
The advantages of dry mixes for preparing monolithic linings for steel ladles are discussed.
In metallurgical processes, the gas phase and, especially,
the liquid phase provide suitable conditions for reactions be-
tween components of the refractory lining and at the refrac-
tory – liquid metal interface. Occasionally, the service life of
refractories and their resistance to attack by molten metal
and slag display a behavior distinct from that normally ex-
pected. In this paper, we report on a study concerned with the
service of refractory materials in the steel-making industry
and discuss the results obtained against theoretical back-
grounds of the refractory technology.
In refractory materials, as in any material system, the
thermodynamic equilibrium is controlled by thermodynamic
potentials that tend to reach a minimum value. The
interphase energy is one of the parameters involved in this
process. By the Second Law of Thermodynamics, condensed
phases are governed by the minimum free-energy principle;
free energy, in turn, depends on the phase surface, interfacial
surface energy, and the location of phase boundaries . In
our case, the liquid phase is either concentrated in pores be
tween crystal grains or occurs as a coating layer between
crystals phase; in this particular situation, no crystalline ag
gregates are formed. It is normally believed that the crystal
phase shows a higher stability and its potential energy is
never too high, whereas the glassy phase is metastable and its
potential energy is quite significant. However, the behavior
of a refractory on its contact with molten metal or slag is
governed not only by the quantitative ratio of phases, but
also by their distribution in the refractory material . It is
generally assumed that in alumina-containing materials ex
posed to high temperatures under non-equilibrium condi
tions, two kinds of liquid phase occur: one, almost free of
alumina, with a relatively low surface tension, and the other,
containing alumina and, consequently, exhibiting a higher
surface tension. As follows from energy considerations, a
liquid with low surface tension is capable of spreading over
the surface of a liquid with high surface tension; the opposite
A means that allows one to control interfacial energies
and phase distributions within the refractory bulk is the intro-
duction of high-temperature surface-active substances (SAS)
. A promising route in refractory technology is design of
the liquid-phase composition that would allow control over
interfacial energy and surface tension temperature coeffi
cient. The liquid phase affects the structure and properties of
refractories during the sintering and under service condi
tions. The impregnation with molten metal is always pre
ceded by the migration of the liquid phase driven by the tem
perature gradient; during this process, the high-temperature
SAS tend to concentrate at the refractory – molten metal in
terface. The infiltrating liquid phase wets the pore walls, fills
the pores, and thereby provides conditions for impregnation.
However, the impregnation can be avoided by adding a liq
uid with a wettability higher than that of the former liquid
phase (molten metal). Of the two liquid phases, the one with
higher wettability will expel the less wetting liquid and
thereby fill small-size pores.
The concentration of high-temperature SAS in molten
metal may vary over a wide range. As was noted in , a ma
jor factor here is the formation of interfacial liquid films. By
varying the viscosity and surface tension of these films, one
can exert control over the behavior of refractory materials.
Refractories and Industrial Ceramics Vol. 46, No. 2, 2005
1083-4877/05/4602-0098 © 2005 Springer Science+Business Media, Inc.
Regional Trading and Industrial Company (RTIC), Ekaterinburg,
Russia; Magnitogorsk Iron and Steel Works (MISW) Joint-Stock
Co., Magnitogorsk, Russia.