ASPECTS OF THE CORROSION OF REFRACTORIES
IN STRUCTURED AGGRESSIVE MEDIA
S. V. Mulevanov,
V. M. Nartsev,
V. A. Doroganov,
E. A. Doroganov,
and S. V. Zaitsev
Translated from Novye Ogneupory, No. 7, pp. 42 – 44, July, 2012.
Original article submitted June 26, 2012.
This article examines aspects of the testing of refractories for corrosion resistance by different methods.
Studies were made of the corrosion resistance of refractories under dynamic conditions by using a special unit
based on rotation of the test specimen in a melt of the corrodent (boron-bearing ultrahard flint, 65% PbO, 35%
). It was determined that corrosion rate increases in proportion to the depth of immersion of the specimen
in the melt. A new method is proposed for determining corrosion rate, the method making it possible to signifi
cantly shorten corrosion tests and improve the accuracy of the results.
Keywords: corrosion, refractory materials, aggressive media, methods of evaluating the corrosion resistance
The different types of aggressive media in which
refractories are used can be conditionally divided into un-
structured media (melts of metals and most salts), weakly
structured media (melts of salt-bearing glasses and metallur-
gical slags with a low content of glass-forming components),
and structured media (glasses having a high content of
glass-forming components and containing additions, such as
, and ZrO
, that increase high-temperature viscos
The corrosion of a refractory in an aggressive melt is a
complex process that includes chemical reaction of the com
ponents of the melt with the refractory material to yield prod
ucts that were absent previously, physical dissolution of the
components of the refractory with a change in their phase
state (including polymorphic transformation and the forma
tion of solid solutions), and physico-mechanical wear (ero
sion); the latter is more pronounced for structured media.
Here, high-temperature viscosity can serve as an integral in
dex of the degree of structuralization of the refractory.
High-temperature viscosity characterizes the internal friction
between the layers of the melt during deformation in shear
The chemical reaction of the refractory with the melt is a
typical heterogeneous reaction which includes three main
stages: delivery of the reacting components to the reaction
surface by molecular diffusion or convection; direct reaction
at the surface; the movement of the reaction products back
into the melt . The rate of the reaction phase of the process
depends on the composition of the refractory and the acid-
base properties of the corrosive medium. Acid refractories
are more stable in non-alkaline and low-alkali melts.
In addition to accounting for the composition of the re-
fractory and the acid-base properties of the aggressive me-
dium, any evaluation of corrosion activity must also consider
the activity of the oxygen anions. As was noted in , ions of
free oxygen O
are the most active anions. The ion fraction
of free oxygen
for glass and slag can be evaluated by
means of the Temkin formula
The initial stage of corrosion of the refractory is directly
dependent on the concentration of free oxygen in the melt.
Within the contact layer, ions of free oxygen can be trans
ferred to the solid phase of the refractory and form a low-vis
cosity melt, which accelerates the refractory’s destruction.
As the thickness of the reaction layer subsequently increases,
the corrosion rate comes to depend mainly on diffusion. The
dependence of corrosion rate K on temperature T is exponen
tial, i.e. it obeys the Arrhenius law :
Refractories and Industrial Ceramics Vol. 53, No. 4, November, 2012
1083-4877/12/05304-0226 © 2012 Springer Science+Business Media New York
Belgorod State Technological University.