REFRACTORIES IN HEAT UNITS
PROTECTIVE COATINGS AS A MEANS OF IMPROVING
HEAT RESISTANCE OF THE REFRACTORY LINING
FOR EXTRA-FURNACE STEELMAKING FACILITIES
S. I. Borovik,
T. N. Ivanova,
N. L. Mironenko,
A. V. Muratov,
and T. V. Yarushina
Translated from Novye Ogneupory, No. 10, pp. 61 – 63, October, 2004.
Original article submitted August 18, 2004.
Protective coatings based on metallic aluminum are developed that can be used to improve the resistance of
the refractory lining for extra-furnace steelmaking facilities. By sintering a slurry sprayed on the refractory
surface, a heat-resistant gas-impermeable coating containing a-corundum is formed.
In extra-furnace steel facilities operating under condi-
tions of vacuum degassing, elevated temperatures, and high
fluid metal and slag flow rates, the wear of the refractory lin-
ing is seldom a slow process. The failure of the refractory
lining in vacuum degassing facilities under industrial condi-
tions is controlled by a range of factors such as the chemical
resistance of refractories (involving reactions between the re-
fractory material and components of molten metal and slag,
especially iron oxides), charge composition, and tempera
ture. As a result, the structural integrity of the refractory ma
terial undergoes degradation, and this process occurs at a
higher rate as compared with conventional exchange reac
tions that take place on the surface of the electric double
layer “slag – refractory” . In steel ladles, specifically strin
gent requirements are placed on the slag-zone refractories
which are exposed to intense thermocyclic erosive and corro
sive attack by fluid slags at high temperature . The lining
for steel ladles and vacuum degassers is conventionally clas
sified by the degradation effect that the above-mentioned
factors produce on the refractory material of the lining. The
most stable for the lining of vacuum degassers are refrac
tories in the system MgO – Cr
, and for the slag
zone of steel ladles — periclase-carbon refractories contain
ing 98 – 99% MgO and 10% graphite.
The major routes towards improving the lining of extra-
furnace steelmaking facilities are: (i) preventing carbon-con-
taining refractories from oxidation; (ii) increasing the resis-
tance of material towards infiltration of fluid metal and slag
under conditions of degassing and high temperatures, and
(iii) use of protective coatings .
In this paper, we are concerned with a feasibility study to
see if protective coatings based on metallic aluminum can
serve for the lining of extra-furnace steelmaking facilities.
The major requirements placed on the protective coat
ings to be developed were resistance to high temperatures
and to mechanical damage and high adhesive ability. The re
sistance of protective coatings was evaluated by applying
them onto periclase-chromite (PCh) and periclase-carbon
(PCa) refractories under industrial and laboratory conditions.
The protective composites were finely dispersed pow
ders of metallic aluminum and metal-emission composite
(MEC, a mixture of inorganic salts) with a specific surface
of 900 and 6300 cm
/g, respectively. To increase the strength
of the protective coating, TiO
was added to the precursor
A number of methods for applying protective coatings
were proposed; of these, deposition from aqueous suspen
sions has gained wide acceptance owing to its simplicity and
moderate temperature conditions . To prevent the suspen
sion from coagulation, a colloidal component (clay or
KMTs-type adhesive) was added. The KMTs adhesive was
used to replace the silicate component — a clay, which is
Refractories and Industrial Ceramics Vol. 46, No. 1, 2005
1083-4877/05/4601-0024 © 2005 Springer Science+Business Media, Inc.
South Ural State University, Chelyabinsk, Russia; Ural Electrode
Institute Joint-Stock Co., Chelyabinsk, Russia; Mechel Joint-
Stock Co. (Chelyabinsk Iron and Steel Works); Kombinat Magne
zit Joint-Stock Co., Satka, Chelyabinsk Region, Russia.