OXIDATION RESISTANCE BEFORE AND AFTER
HEAT TREATMENT FOR COMPACTED Al
WITH ALUMINUM-CHROMIUM-PHOSPHATE BINDER
L. A. Angolenko,
G. D. Semchenko,
S. V. Tishchenko,
and V. N. Sidorov
Translated from Novye Ogneupory, No. 2, pp. 38 – 43, February, 2009.
Original article submitted September 24, 2008.
Oxidation resistance has been examined for compacted Al
–SiC–C mixtures, which contain an alumi
num-chromium-phosphate binder without firing (DTA method) and ones that have been previously fired and
given isothermal heat treatment at 800°C (as indicated by the mass loss). To obtain oxidation-resistant materi
als, the content of silicon carbide should not exceed 10 wt.% and the recommended graphite content is not
more than 20 wt.%.
Keywords: compacted mass, corundum-graphite material, aluminum chromium-phosphate binder, open po
rosity, oxidation resistance.
The wear in corundum-graphite refractory components is
due [1, 2] to the formation of a decarburized zone by the oxi-
dation of the graphite and the peeling of it due to structural
cracking . The decarburized zone at the working surface
of the lining is formed by gaseous oxidation of the graphite
by oxygen and liquid phase oxidation by slag components
There are methods of protecting graphite in refractory
materials as follows: chemical (antioxidants), structural (for
mation of a dense structure), and physical (depositing coat
The simplex method has been used  to examine the ef
fects of changing the amount of antioxidant (silicon carbide)
on the density and strength of the material. We have exam
ined the oxidation resistance of compacted material based on
-SiC-C mixtures with aluminum-chromium-phosphate
binder (ACPB). It is also of interest to examine the effects of
the amount of SiC as antioxidant and also as a consolidating
structure component as regards the oxidation resistance of
these molded refractories, and it is also of interest to examine
the relationship between the structure of the material and the
Differential thermal analysis (DTA) has been applied to
the processes occurring on heating corundum-graphite bod
ies containing silicon carbide (Table 1) with aluminum-chro
mium-phosphate binder. Figure 1a shows the results.
There is an endothermic effect at 110 – 130°C due to the
removal of physical water. The loss of residual water from
specimen No. 26 based on electrocorundum and ACPB as re-
gards the DTA curve is accompanied by an endothermic ef-
fect at 130°C, while for specimen No. 24 containing
electrocorundum, 5% graphite
, and ACPB, this occurs at
120°C, while for specimen No. 33 containing electro-
corundum, 20% graphite, 5% SiC, and ACPB has the water
loss at an even lower temperature (110°C). Then as the
amount of graphite in the corundum mixture with the ACPB
increases, the water is lost at a lower temperature, which is
due to graphite being hydrophobic. Similarly, the removal of
residual water is influenced by 5% SiC, where the endother
mic effect is lowered to a temperature of 120°C.
The DTA curves for materials containing 5 and 20%
graphite (Nos. 24, 25, and 33) have exothermic peaks at 880,
885, and 970°C (see Fig. 1a ), which correspond to the oxi
dation of the graphite. In specimens No. 24 and 25 with the
lower graphite content, the oxidation is more rapid and be
gins at a lower temperature, with maxima at 880 and 885°C,
while in No. 33 with the higher graphite content, the maxi
mum temperature for the oxidation is 970°C, i.e., increasing
the graphite content by a factor 4 raises the oxidation temper
ature by 85 – 90°C because the thermal conductivity of the
is less than that of graphite by a factor 7. Conse
quently, the heat produced by the exothermic reactions accu
Refractories and Industrial Ceramics Vol. 50, No. 1, 2009
1083-4877/09/5001-0052 © 2009 Springer Science+Business Media, Inc.
Kharkov Polytechnical Institute, Ukraine.
Ukrainian Engineering Teaching Academy, Kharkov, Ukraine.
Here and subsequently, the contents of components in the charge
and the mass losses are given in weight percent.