THE DOPANT-MODIFIED STRUCTURE AND PROPERTIES OF CORUNDUM
REFRACTORIES FOR SLOT-NOZZLE BLOWING FACILITIES
S. I. Kazakov,
S. I Borovik,
T. N. Ivanova,
A. M. Chuklai,
and O. I. Frolov
Translated from Novye Ogneupory, No. 6, pp. 22 – 25, June, 2006.
Original article submitted April 12, 2006.
The effect of dopants graphite, boron carbide, and crystalline silicon on the physicomechanical and thermal
properties of corundum-carbon refractories used in the fabrication of slot-nozzle tuyeres for off-furnace steel
processing is discussed.
Inert gas injection into molten metal ladle is currently be-
coming a trend in the off-furnace steel metallurgy. This tech-
nique involves processes essential for improving the metal
quality: it makes the stirring of molten metal more effective
owing to the gas bubbling; improves the homogeneity of the
molten metal in temperature and chemical composition; re-
duces the concentration of undesired gaseous impurities; re-
duces the concentration of contaminants such as oxides and
sulfur compounds, and facilitates dissolution and uniform
distribution of deoxidizers, alloying agents, and slag-forming
A shortcoming of the gas injection technique is that it
promotes corrosion of the ladle lining. The tuyeres through
which an inert gas is supplied to the ladle become exposed to
the most heavy-duty conditions 
Apart from the main damaging factors — thermal and
mechanical stresses, corrosive and erosive attack by stirred
metal and slag, and bubble cavitation effect — other factors
that specifically affect the performance of slot-nozzle injec
tion tuyeres are added: thermal stress associated with the
cooling and erosive action of the gas jet on the injection duct
and the enhanced risk of molten metal ingress into the gas in
let system, frequently resulting in the duct clogging.
To enhance the stability of slot-nozzle injection facilities
(henceforth slot tuyeres for simplicity) against thermome
chanical stress, and spalling and penetration of molten metal
into the tuyere’s slot nozzles, high-strength and thermore
sistant refractory materials with minimum open porosity
should be used.
Promising materials for that purpose are corundum-car-
bon refractories . Adding antioxidizing and structure-for-
ming agents to the precursor mixture may provide the re-
quired physicomechanical, structural, and operational pro-
perties of the material .
In this work we have studied the effect of additives (do-
pants) on the properties of corundum-carbon materials in-
tended for the manufacture of slot-nozzle tuyeres for use in
off-furnace steel treatment. The objects of study were labora
tory specimens molded under pressure from fused corundum.
The binding material was a phenolic powder (PP) and ethy
lene glycol (EG). The composites differed in structure-form
ing agents added. Composite 1 contained no dopant; com
posite 2 contained artificial graphite and boron carbide
C); composite 3 contained artificial graphite, boron car
bide, and crystalline silicon.
The dopants introduced into the refractory matrix pro
duce a pronounced effect on physicomechanical properties
and micro- and macrostructure of the material (Table 1;
Figs. 1 – 3). Corundum and corundum-carbon materials
heat-treated at operating temperatures (1000 – 1700°C) de
velop a range of sequential and parallel reactions that exert
an individual effect on properties and structure of the refrac
tory material. Processes that occur in the temperature range
of 20 – 1000°C are illustrated by thermogravimetric analysis
data in Fig. 4.
At low temperatures (up to 300°C), the weight loss is
mainly associated with the removal of adsorbed atmospheric
moisture from the surface of material particles, polymeriza
Refractories and Industrial Ceramics Vol. 47, No. 3, 2006
1083-4877/06/4703-0189 © 2006 Springer Science+Business Media, Inc.
Magnitogorsk Iron and Steel Works (MISW) Joint-Stock Co.,
Magnitogorsk, Russia; South Ural State University, Chelyabinsk,
Russia; Ural Electrode Institute Joint-Stock Co., Chelyabinsk,
Russia; Terg-K Research and Production Association, Russia.