CERAMIC REFRACTORY SHS-COATINGS
BASED ON THE SYSTEM Al–SiO
K. B. Podbolotov,
E. M. Dyatlova,
and R. Yu. Popov
Translated from Novye Ogneupory, No. 10, pp. 31 – 36, October, 2013.
Original article submitted June 28, 2013.
Preparation of refractory coatings by self-propagating high-temperature synthesis (SHS) based on the system
on aluminum silicate refractories using quartz sand and kaolin from the Belorussian Republic is stud
ied. It is established that use of a mixture of kaolin and quartz sand reduces the probability of crack formation
in a coating during drying and firing, and improves its qualitative properties. It is shown that coating refracto
riness higher than 1300°C is only achieved using binders not containing sodium salts. Physicochemical and
thermal properties of synthesized ceramic SHS-materials and coatings based on them are studied. The effect
of additives on these properties is established. High adhesive strength is apparent for coatings containing addi
tions of titanium dioxide and boric acid.
Keywords: SHS-coating, exothermic synthesis, binder, refractoriness, thermal shock resistance, mullite.
Of the considerable amount of refractory materials used
currently the most widespread are aluminosilicate with a
mullite weight content of 61 – 72% [1 – 3]. It is possible to
prepare these refractory compositions in an SHS regime.
This phenomenon, discovered in 1957, has been used exten
sively as a result of saving energy during synthesis of valu
able products in a solid-flame combustion regime [4 – 8].
Use of SHS is known for preparing mortars, and also
various mastics, coatings, and other similar materials, which
are used in manufacturing furnace linings as a mortar or for
sealing and protecting a furnace lining from the action of
gases, dust, and sharp temperature drops, etc.
From a practical point of view in order to prepare various
materials for structural purposes (lining materials,
refractories, light cellular concretes, heat- and flame-protec
tion materials), SHS-systems are especially preferred, con
taining silicon dioxide SiO
, and this component is the basis
of the majority of natural materials and building industry
waste [9 – 11].
Research of Mal’tsev and others [12, 13] is worthy of at
tention, who developed material containing mullite of the
, where X = 0.68 – 0.70 and
Y = 0.33. The material was prepared by exothermic synthesis
of a starting charge, containing 70 – 80% silicon dioxide,
20 – 30% alumina and 35%-water glass solution in an
amount of 16 – 18% of the charge weight. The starting mix-
ture may additionally contain 10 – 40% silicon carbide. The
silica-containing component in the starting mixture is sand
grade S-070-1, containing 98.3% SiO
, being an oxidizing
agent of the system, and aluminium metal powder as ASD-1
is used as a reducing agent.
The main components of SHS-mortars in relation to type
may be aluminum metal powder, aluminosilicate (mullite-co
rundum) filler, silica, periclase, chromite concentrate, and
various modifying additives. Practical use of SHS-mortars is
similar to using mortars prepared by traditional technology.
After preparation of a starting mix it is applied to an individ
ual refractory object in a layer 3–5mmthick during furnace
lining installation, and dried for 1 h. Heating of a lining and
joint is normally accomplished due to supply of molten metal
or incandescent gases. During lining heating to 900 – 1100°C
the joint ignites and burns at a rate of 1 mm/sec, and the tem
perature in the combustion zone reaches 1500 – 1900°C
[14 – 17].
After completing the combustion stage a joint almost im
mediately acquires the required strength. SHS-mortar with
respect to adhesive strength is significantly (by a factor of
3 – 4) better than traditionally prepared mortars. This effect
is due to the fact that in the course of SHS due to develop
ment of high temperature within a combustion zone there is
not only synthesis of refractory joint materials, but also si
Refractories and Industrial Ceramics Vol. 54, No. 5, January, 2014
1083-4877/14/05405-0401 © 2014 Springer Science+Business Media New York
Belorussian State Technological University, Minsk, Belarus.