PROPERTIES OF MATERIALS OF THE SYSTEM Al
AFTER FIRING IN A REDUCING ATMOSPHERE
L. A. Angolenko,
G. D. Semchenko,
S. V. Tishchenko,
and O. V. Stepanyuk
Translated from Novye Ogneupory, No. 10, pp. 52 – 56, October 2007.
Original article submitted April 4, 2007.
A set of studies is presented for the physicomechanical properties of corundum-graphite carbide-containing
refractories. The efficiency of introducing silicon carbide as an antioxidant addition to Al
rials is established. The structure and phase composition of corundum-graphite silicon carbide-containing
refractories based on an ethyl silicate binder fired in a reducing atmosphere are studied.
Under contemporary conditions the role of refractory
materials with a set of valuable properties such as heat resis-
tance, high corrosion and erosion resistance, mechanical
strength, constantly increases. On one hand, as a result of the
introduction of new advanced technology the overall volume
of the requirement for refractory materials decreases, and on
the other hand at the same time an improvement is noted in
the qualitative characteristics [1 – 8].
One of the most important methods for improving graph-
ite-containing refractories is development of methods for
protecting carbon from oxidation, and this may be resolved
by adding metals, oxygen-free compounds and other mate
rials, that actively react with oxygen, they form a liquid
phase and create a coating of the “glaze” type preventing dif
fusion of oxygen into the refractory. Resistance to oxidation
of the material obtained depends on the nature and quality of
the newly formed synthesizes secondary phases that form in
the intergranular space and at boundaries, and also over the
surface grains. Here additions should carry some engineering
load as much as possible, for example promote an increase in
ductility of the formable mix, reduce the lower temperature
limit for the mix sintering range, and increase the density of
the sintered material, which reduces access of oxygen to the
surface of graphite flakes and reduces the oxidizing capacity
of the material as a whole.
Silicon carbide is added to a charge in order to give co
rundum-graphite articles increased heat and abrasion resis
tance. In addition, it forms with oxidation of articles a pro
tective film that prevents further burning of graphite .
Recently a study has been made of the properties of co
rundum-graphite silicon carbide materials, prepared by
semi-dry compaction using modified ethyl silicate hydro-
lyzates as a binder (Fig. 1). Specimens were fired in a reduc-
ing atmosphere at 1450ºC with soaking for 3 h.
Introduction into the composition of the mix of silicon
carbide, that provides high erosion resistance, resistance to
oxidation, fulfilling the role of an antioxidant, and also use of
modified ethyl silicate binder, that satisfactorily protect
graphite, give strength to the raw material, limit oxidation of
graphite and are a source of amorphous SiO
that has a ca-
pacity to enter into reaction with a-Al
with formation of
mullite, gives rise to the desirability of carrying out studies
directed towards optimizing the composition of corundum-
Refractories and Industrial Ceramics Vol. 48, No. 5, 2007
1083-4877/07/4805-0368 © 2007 Springer Science+Business Media, Inc.
National Technical University “Kharkov Polytechnic Institute”,
in a ball mill (30 h)
a-Al O (ground)
SiC Graphite Binder
Fig. 1. Production scheme for preparing corundum-graphite silicon
carbide materials based on ethyl silicate binder (ÉTS-32).