FIELD OF THE INVENTION
The present invention relates to oxidation and corrosion resistant Magnesia carbon
refractory brick composition. More particularly, the present invention is directed to a class of
higher carbon containing Magnesia carbon refractory bricks involving a new dual antioxidant
comprising aluminium and boron carbide and a process for manufacturing these bricks. The
Magnesia carbon refractory brick product according to the present invention is fit for use as
refractory lining of liquid steel processing vessels wherein aluminium and born carbide
content is optimized to ensure controlled spinel and glassy phase formation to achieve
desired higher oxidation resistance and thereby, favourably good corrosion resistance
towards steel making slag along with good hot strength. The invented class of Magnesia
carbon refractory bricks are expected to perform better than conventional Magnesia carbon
bricks containing only one antioxidant (i.e. aluminium) in steel processing vessels,
particularly, steel ladles in a cost effective manner.
BACKGROUND ART
The development and refinement of magnesia-carbon brick, involving compositions,
production processes and application know-how, directed to improved performance and
reliability with enhanced service life has been the trends of advancements in refractories
during the past 20 years. It is well known in the related art that the basic ingredients for the
manufacture of these bricks are sintered and fused magnesia together with graphite and
other carbon contributors. Organic materials (e.g., resin, pitch etc.) with high carbon yield
after coking are used as binders in order to ensure a sufficient bond while the bricks are in
service. Metal powders such as Al, Si or Mg, known as antioxidants, are usually added to
influence specific brick properties.
Carbon has been recognized as an essential component of refractories in the art to resist
corrosive high-temperature slag generated in the steel making processes. There has been a
continued effort to develop improved carbon containing magnesia brick, where carbon is an
integral part of a magnesia-carbon composite.
Of great significance to the development of this new refractory class was the realization of
the beneficial characteristics of flake graphite compared to other forms of carbon, i.e.,
superior oxidation resistance, high thermal conductivity, low co-efficient of thermal
expansion etc. in the resulting brick.

Importance and significance of carbon can be seen in the wear reduction by reducing
infiltration depth and in the bond of the unfired bricks with characteristic structure flexibility.
The non-wetting characteristics of the flake graphite greatly contribute in improving this slag
corrosion resistance of the magnesia carbon brick. In addition, thermal shock resistance is
improved due to much higher thermal conductivity and very low thermal expansion of
graphite.
It is further a known phenomenon for application of magnesia carbon bricks as refractory,
that aluminium in bricks starts reacting above 700-800°C with the carbon in the brick to
form aluminium carbide (AI4C3). At a temperature above 1100°C, this AI4C3 subsequently is
oxidized to form Al2O3 which reacts with MgO to form spinel (MgO. Al2O3). The expansion
associated with in-situ spinel formation densifies the matrix improving strength and also
seals pores. However, with increase in Al content, the above phase transformation ( AI4C3 =>
Al2O3 => MgO. AI2O3 ) reaction will generate spinel in larger amount. This may cause
excessive expansion resulting in damage of the brick structure at the oxidation reaction
interface.
Research efforts are directed to improve oxidation resistance property and investigated
performance of different metals, alloys as antioxidants including in particular boron bearing
compounds. Literatures revealed that boron carbide (B4C) react with CO prevailing in the
brick to form B2O3, which further reacts with MgO to form glassy phases like 3MgO.B2O3.
These glassy phases form a protective coating on the graphite flakes and also seal the
pores, thus improving oxidation resistance. However, too much formation of these glassy
phases may reduce hot strength property of MgO-C bricks.
There has been therefore a persistent need in the field of developing magnesia carbon brick
composition as well as production processes to develop bricks with higher oxidation
resistance by retaining carbon in the brick matrix so that the benefits resulting from carbon
are more and more realized without sacrificing much of the hot strength of refractory bricks.
Attempts have been made in this direction by way of the present invention to developing a
magnesia carbon brick composition which would one hand ensure the optimized addition of
aluminium and born carbide as dual antioxidants, and on the other hand result in desired
oxidation and corrosion resistance without sacrificing much of hot strength favouring
application of such bricks for liquid steel processing vessels/steel ladles with improved
performance and longer service life.

OBJECTS OF THE INVENTION
The basic object of the present invention is thus directed to developing a Magnesia carbon
refractory brick composition having desired properties suitable for application in refractory
lining of liquid steel processing vessels/steel ladles.
A further object of the present invention is directed to developing a magnesia carbon brick
composition comprising dual antioxidant in the form of intimate mixture of fine powders of
Aluminium and Boron carbide directed to achieving higher oxidation resistance and slag
corrosion resistance with high hot strength.
A still further object of the present invention is directed to developing a magnesia carbon
brick composition involving dual antioxidant wherein the glassy phase formation at high
service temperature is controlled and graphite is protected from oxidation by optimizing the
proportion of Aluminium and Boron carbide in brick composition.
A still further object of the present invention is directed to developing a magnesia carbon
brick composition involving dual antioxidant wherein aluminium content is selectively
controlled and unwanted expansion due to excessive spinel formation is avoided to eliminate
the problem of damage of brick structure at the oxidation reaction interface.
A still further object of the present invention is directed to developing a magnesia carbon
brick composition involving dual antioxidant wherein batch composition is decided through
extensive trial to achieve desired properties i.e. oxidation resistance, hot strength, slag
corrosion resistance and other physical properties in resulting refractory bricks.
A still further object of the present invention is directed to developing a magnesia carbon
brick composition involving dual antioxidant wherein batch composition is selectively
maintained to ensure desired densification of brick matrix as well as to improve thermal
shock resistance during service by improving protection of carbon from oxidation.
A still further object of the present invention is directed to developing a magnesia carbon
brick composition involving dual antioxidant wherein a particular mixing sequence is
followed for the various ingredients to favour achieving desired properties in the resulting
bricks.
A still further object of the present invention is directed to developing a magnesia carbon
brick composition involving dual antioxidant wherein the proportion of ingredients and

respective grain/particle sizes selectively maintained and the process parameters are
optimized to obtain desired properties of bricks in terms of parameters comprising apparent
porosity (AP), coked porosity, cold crushing strength (CCS), permanent linear change
(PLCR) after heating at operating temperature and favourable phase change and
microstructure to ensure reliable performance and service life of bricks.
SUMMARY OF THE INVENTION
The basic aspect of the present invention is thus directed to a magnesia carbon brick
composition comprising:
(1) Fine powder of metallic aluminium (1-2.5 parts by weight)
(2) Fine powder of boron carbide (0.2-0.5 parts by weight)
(3) Sintered sea water magnesia fines (15-18 parts by weight)
(4) Sintered sea water magnesia micro-fines (9-12 parts by weight)
(5) Flake graphite powder (5-13 parts by weight)
(6) Fine powder of pitch (0.5-1.0 parts by weight)
(7) Fused Magnesia/Sintered sea water Magnesia grains (60-65 parts by weight)
A further aspect of the present invention is thus directed to said composition wherein, the
desired grain sizes of different ingredients comprise:
(1) Magnesia grains (Fused/Sintered sea water) : 0.5 to 4 mm
(2) Sintered sea water magnesia fines : < 0.5 mm
(3) Sintered sea water magnesia micro-fines : < 90 µm
(4) Fine powder of metallic aluminium : < 74 µm
(5) Fine powder of boron carbide : < 44 µm
(6) Flake graphite powder : < 0.3 mm
(7) Fine powder of pitch : < 0.3 mm
A still further aspect of the present invention is directed to said composition wherein, the
MgO content of different magnesia sources comprise:
(1) Magnesia grains (Fused/Sintered sea water): MgO - 97% min.
(2) Sintered sea water magnesia fines : MgO - 97% min.
(3) Sintered sea water magnesia micro-fines : MgO - 97% min.

A still further aspect of the present invention is directed to a composition wherein, the
graphite comprises :
Fixed carbon (FC) : 96.0% min.
Volatile matter : 0.50% max.
Moisture : 0.50% max.
Ash 3.0% max.
Importantly in said Composition, the aluminium content in aluminium powder is 99.5% min.
A still further aspect of the present invention directed to said composition wherein, the
boron carbide powder comprises:
B4C 95% min.
Boron 75% min.
Carbon 20% max.
Boron (free) 0.5% max.
Also in said composition according to the invention, the coking residue in pitch powder is 45
to 55% min. with softening point of 125 to 135°C (R&B).
According to a further aspect of the present invention directed to said composition
comprising of "resol" resin binder having:
Non volatile matter 70-75%
Fixed carbon 40-45% min.
Viscosity at 25°C 250-350 cps
Sp. Gravity at 25°C 1.17-1.21
According to yet another aspect of the present invention directed to said composition
wherein :
1. said sintered sea water magnesia (grains, fines and micro-fines) comprises :
MgO 97.0% min.
SiO2 0.35% max.
Al2O3 0.12% max.
Fe2O3 0.20% max.
CaO 2.40% max.
B2O3 0.02% max.

Bulk Sp. Gr. 3.40 min.
Crystal size 100 urn min.
2. said fused magnesia grains comprises :
MgO 97.0% min.
SiO2 0.60% max.
Al2O3 0.20% max.
Fe2O3 0.80% max.
CaO 1.20% max.
Loss on ignition (LOI) 0.25% max.
Bulk Sp. Gr. 3.50 min.
Crystal size 400 µm min.
CaO : SiO2 2:1 min.
3. said Graphite (Flake) comprises :
Fixed carbon (FC) 96.0% min.
Volatile matter (VM) 0.50% max.
Moisture 0.50% max.
Ash 3.0% max.
Particle size:
-72 mesh BSS (below 0.210 mm): 20% max.
-52 mesh BSS (below 0.297 mm): 80% min.
+44 mesh BSS (above 0.35 mm): 7% max.
4. said Pitch powder comprises :
Fixed carbon (FC) 45-55% min.
Volatile matter (VM) 45-55% max.
Softening point (Ring & Ball) 125-135°C
Ash 1.5% max.
Particle size:
-1.0 mm 100%
+0.3 mm 5% max.
5. said Aluminium powder comprises :
Al 99.5% min.

Si 0.15% max.
Fe 0.40% max.
Particle size:
+200 mesh BSS (above 0.075 mm) 10% max.
-325 mesh BSS (below 0.044 mm) 40% min.
6. said Boron carbide comprises :
B4C 95.0% min.
Boron 75.0% min.
Carbon 20% max.
Boron (free) 0.50% max.
B2O3 0.50% max.
Fe 0.50% max.
Si 0.30% max.
Particle Size 95% passing through 325 mesh BSS
7. said "Resol" resin comprises :
Non volatile matter (NVM) 70-75%
Fixed carbon (FC) 40-45% min.
Viscosity at 25°C 250-350 cps
Sp. Gravity at 25°C 1.17-1.21
pH 6.5-6.9
Free moisture 5-7%
Free phenol 14±2%
Free formaldehyde 0.8+0.2%
Ash 0.2% max.
Water solubility at 25°C 100:50 (Resin:Water) min.
A still further aspect of the present invention is directed to a process for the manufacture of
magnesia carbon brick from the magnesia carbon brick composition comprising:
i) providing mix of fused Magnesia and sintered sea water magnesia grains;
ii) adding to the mix of step (i) above the resin;
iii) adding to the mix of step (ii) above the Graphite;

iv) separately, mixture (herein after called "premix") is prepared by intimately
mixing fine powders of Aluminium, Boron carbide and sea water magnesia
micro fines;
v) adding to the mix of step (iii) above the resin and "premix";
vi) adding to the mix of step (v) above the pitch powder, sintered sea water
magnesia fines and resin to obtain a final mix ;
vii) subjecting the said final mix of step (vi) above to steps of ageing, pressing,
curing and thereby obtaining the said brick.
A still further aspect of the present invention is directed to said Magnesia carbon brick
obtained involving the composition comprising:

The present invention and its objects and advantages are described in greater details with
reference to the following non limiting accompanying drawing and example.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURE
Figure 1: is the flow chart showing the mixing sequence of magnesia carbon brick
composition and steps involved in process for producing such bricks according to the present
invention.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING FIGURE AND EXAMPLE
The present invention is directed to developing a magnesia carbon brick composition
comprising aluminium and boron carbide based dual antioxidant adapted to ensure excellent
oxidation resistance, slag corrosion resistance along with good hot strength of the resulting
refractory bricks produced using such composition. The ratio of aluminium and boron
carbide is selectively used with other ingredients to achieve the desired properties of the
refractory bricks. The optimum composition is decided through a large number of trials
made with varied proportions of ingredients. The new composition contains a novel dual
antioxidant in the form of intimate mixture of fine powders of Aluminium and Boron carbide
directed to achieving higher oxidation resistance and slag corrosion resistance with high hot
strength. The details of the magnesia carbon brick composition and the process of producing
refractory bricks using such composition for application in steel processing vessels/ladles are
described with the help of following example.
EXAMPLE I:
Extensive laboratory work has been carried out to develop compositions using the new dual
antioxidant according to the invention. Samples have been prepared using developed
composition with dual antioxidant as well as with conventional aluminium antioxidant
containing composition. The amount of different raw materials and additives except
antioxidant are kept same. Total amount of antioxidant are also kept same in the different
formulations. Only the ratio of aluminium and boron carbide in the total antioxidant are
varied.
(i) According to an embodiment of the present invention the proportion of different
ingredients used to produce the magnesia carbon brick composition comprised the following:
Fine powder of metallic aluminium in the range of 1-2.5 parts by weight;
Fine powder of boron carbide in the range of 0.2-0.5 parts by weight;
Sintered magnesia sea water fines in the range of 15-18 parts by weight;
Sintered sea water magnesia micro-fines in the range of 9-12 parts by weight;
Flake graphite powder in the range of 5-13 parts by weight;
Fine powder of pitch in the range of 0.5-1.0 parts by weight;
Magnesia grains (Fused/Sintered sea water) in the range of 60-65 parts by weight;

(ii) The preferred grain sizes for the above constituents are selected in the range as follows:
Magnesia grains (Fused/Sintered sea water): 0.5 to 4 mm
Sintered sea water magnesia fines : < 0.5 mm
Sintered sea water magnesia micro-fines : < 90 µm
Fine powder of metallic aluminium : < 74 µm
Fine powder of boron carbide : < 44 µm
Flake graphite powder : < 0.3 mm
Fine powder of pitch : < 0.3 mm
(iii) The desired MgO content of different magnesia sources (Fused/Sintered) used in the
above constituents are as follows:
Magnesia grains (Fused/Sintered sea water) : MgO - 97% min.
Sintered sea water magnesia fines : MgO - 97% min.
Sintered sea water magnesia micro-fines : MgO - 97% min.
(iv) The desired purity of other components used in the magnesia carbon brick composition
are as follows:
Fine powder of metallic aluminium : Al - 99.5% min.
Fine powder of boron carbide : B4C - 95% min.
Boron - 75% min.
Carbon - 20% max.
Boron (free) - 0.5% max.
Flake graphite powder : Fixed carbon - 96% min.
Fine powder of pitch : Fixed carbon - 45-55% min.
(v) The binder used to produce bricks from said composition is liquid "resol" type resin,
having properties of the said binder as follows:
Non volatile matter 70-75%
Fixed carbon 40-45% min.
Viscosity at 25°C 250-350 cps
Sp. Gravity at 25°C 1.17-1.21
The properties of graphite in said composition are as follows:

Fixed carbon (FC) : 96.0% min.
Volatile matter : 0.50% max.
Moisture : 0.50% max.
Ash 3.0% max.
The properties of boron carbide powder used in the composition are as follows:
B4C 95% min.
Boron 75% min.
Carbon 20% max.
Boron (free) 0.5% max.
According to an aspect of the present invention directed to said magnesia carbon brick
composition wherein the following are ensured:
a) The ratio of Aluminium and boron carbide is within 4-5 with boron carbide as minor
constituent.
b) A "premix" is prepared first comprising aluminium powder, boron carbide powder and
sintered sea water magnesia micro fines by intimately mixing these three ingredients.
c) The quantity of resin in the mix is 3.5 to 4.0% max.
Process of manufacturing the bricks:
Reference is invited to the accompanying Figure 1 that schematically illustrate the flow
chart showing the mixing sequence of magnesia carbon brick composition and steps
involved in process for producing such bricks according to the present invention.
(i) The particular mixing sequence of the ingredients as given in accompanying Figure 1, in
required proportions as stated above is followed to achieve desired properties of the bricks
produced using said composition, prepared using a mixer machine as follows:
(a) Fused magnesia and sintered sea water magnesia grains are first mixed to form a Mix
(Ml);
(b) Mixing liquid "resol" type resin with mix (Ml) obtained in first step to produce mix (M2);

(c) Mixing graphite with mix (M2) obtained in second step to form mix (M3);
(d) a separate "premix" is obtained in the form intimate mixture of fine powders of
Aluminium, Boron carbide and sea water magnesia micro fines for preparing mix;
(e) "premix" of step four and the Yesol' type resin is further mixed in required proportion
with mix (M3) obtained in step three to form mix (M4);
(f) Pitch powder, sintered sea water magnesia fine and resin are then mixed thoroughly with
the mix M4 obtained in the preceding step to form the final mix (M5);
(g) subjecting the said final mix of step (f) above to steps of ageing, pressing, curing and
thereby obtaining the said brick.
(h) finished bricks are stacked after sorting, inspection and testing.
Testing of the bricks produced by the process:
(i) Detailed thermo-mechanical evaluation has been carried out under same test conditions
for all the formulations. Oxidation resistance test is done with sample bricks by firing the
samples in a furnace at 1000°C for 2 hours in oxidizing atmosphere along with samples
containing conventional single antioxidant (Aluminium) for comparing oxidation resistance.
The oxidation resistance index is computed based on area of retained carbon core in the
samples. It has been found that dual antioxidant containing samples are having up to 29%
more oxidation resistance as compared to conventional single antioxidant containing
samples. The other properties of new dual antioxidant containing formulations have been
found to be equivalent or better than the single antioxidant containing compositions. The
invented brick composition has been tested for reliable performance with respect to
parameters comprising apparent porosity (AP), coked porosity, cold crushing strength
(CCS), permanent linear change (PLCR) after heating at operating temperature, XRD
analysis for phase studies and Scanning electron microscope analysis for microstructure
studies etc.
Comparative properties of Magnesia carbon bricks with conventional antioxidant and with
new dual antioxidant are given in accompanying table-1.


It is thus possible by way of the present invention to providing magnesia carbon brick
composition involving aluminium and boron carbide based dual antioxidant and a process for
manufacturing magnesia carbon bricks using such composition for application in steel
processing vessels, particularly, steel ladles in a cost effective manner for improving
refractory life and performance. Importantly, the refractory bricks produced according to the
invention having higher oxidation resistance and slag corrosion resistance accompanied with
favourably high hot strength. The ratio of aluminium and the boron carbide is selectively
maintained in the composition to optimize and control the extent of spinel generation and
resultant excessive expansion at the oxidation reaction interface and on the other hand to
glassy phase formation directed to form an oxidation resistant coating on the graphite
flakes, leading to desired structure and strength property in the resulting bricks.

We claim:
1. A magnesia carbon brick composition comprising:
(1) Fine powder of metallic aluminium (1-2.5 parts by weight)
(2) Fine powder of boron carbide (0.2-0.5 parts by weight)
(3) Sintered sea water magnesia fines (15-18 parts by weight)
(4) Sintered sea water magnesia micro-fines (9-12 parts by weight)
(5) Flake graphite powder (5-13 parts by weight)
(6) Fine powder of pitch (0.5-1.0 parts by weight)
(7) Fused Magnesia/Sintered sea water Magnesia grains (60-65 parts by weight)
2. Composition as claimed in claim 1, wherein, the desired grain sizes of different
ingredients comprise:
(1) Magnesia grains (Fused /Sintered sea water) : 0.5 to 4 mm
(2) Sintered sea water magnesia fines : < 0.5 mm
(3) Sintered sea water magnesia micro-fines : < 90 µm
(4) Fine powder of metallic aluminium : < 74 µm
(5) Fine powder of boron carbide : < 44 µm
(6) Flake graphite powder : < 0.3 mm
(7) Fine powder of pitch : < 0.3 mm
3. Composition as claimed in anyone of claims 1 to 2, wherein, the MgO content of
different magnesia sources comprise:
(1) Magnesia grains (Fused/Sintered sea water) : MgO - 97% min.
(2) Sintered sea water magnesia fines : MgO - 97% min.
(3) Sintered sea water magnesia micro-fines : MgO - 97% min.
4. Composition as claimed in anyone of claims 1 to 3, wherein, the graphite comprises :
Fixed carbon (FC) : 96.0% min.
Volatile matter : 0.50% max.
Moisture : 0.50% max.
Ash 3.0% max.
5. Composition as claimed in anyone of claims 1 to 4, wherein, the aluminium content in
aluminium powder is 99.5% min.

6. Composition as claimed in anyone of claims 1 to 5, wherein, the boron carbide powder
comprises:
B4C 95% min.
Boron 75% min.
Carbon 20% max.
Boron (free) 0.5% max.
7. Composition as claimed in anyone of claims 1 to 6, wherein, the coking residue in
pitch powder is 45 to 55% min. with softening point of 125 to 135°C (R&B).
8. Composition as claimed in anyone of claims 1 to 7, comprising of "resol" resin binder
having:
Non volatile matter 70-75%
Fixed carbon 40-45 min.
Viscosity at 25°C 250-350 cps
Sp. Gravity at 25°C 1.17-1.21
9. Composition as claimed in anyone of claims 1 to 8 wherein :
a) said sintered sea water magnesia (grains, fines and micro-fines) comprises :
MgO 97.0% min.
SiO2 0.35% max.
Al2O3 0.12% max.
Fe2O3 0.20% max.
CaO 2.40% max.
B2O3 0.02% max.
Bulk Sp. Gr. 3.40 min.
Crystal size 100 µm min.
b) said fused magnesia grains comprises :
MgO 97.0% min.
SiO2 0.6% max.
Al2O3 0.20% max.
Fe2O3 0.80% max.
CaO 1.20% max.
Loss on ignition (LOI) 0.25% max.
Bulk Sp. Gr. 3.50 min.
Crystal size 400 µm min.
CaO : SiO2 2:1 min.

c) said Graphite (Flake) comprises :
Fixed carbon (FC) 96.0% min.
Volatile matter (VM) 0.50% max.
Moisture 0.50% max.
Ash 3.0% max.
Particle size:
-72 mesh BSS (below 0.210 mm): 20% max.
-52 mesh BSS (below 0.297 mm): 80% min.
+44 mesh BSS (above 0.35 mm): 7% max.
d) said Pitch powder comprises :
Fixed carbon (FC) 45-55% min.
Volatile matter (VM) 45-55% max.
Softening point (Ring & Ball) 125-135°C
Ash 1.5% max.
Particle size:
-1.0 mm 100%
+0.3 mm 5% max.
e) said Aluminium powder comprises :
Al 99.5% min.
Si 0.15% max.
Fe 0.40% max.
Particle size:
+200 mesh BSS 10% max.
-325 mesh BSS 40% min.
f) said Boron carbide comprises :
B4C 95.0% min.
Boron 75.0% min.
Carbon 20% max.
Boron (free) 0.50% max.
B2O3 0.50% max.
Fe 0.50% max.
Si 0.3% max.
Particle Size 95% passing through 325 mesh BSS
g) said "Resol" resin comprises :

Non volatile matter (NVM) 70-75%
Fixed carbon (FC) 40-45% min.
Viscosity at 25°C 250-350 cps
Sp. Gravity at 25°C 1.17-1.21
PH 6.5-6.9
Free moisture 5-7%
Free phenol 14±2%
Free formaldehyde 0.8+0.2%
Ash 0.2% max.
Water solubility at 25°C 100:50 (Resin:Water) min.
10. A process for the manufacture of magnesia carbon brick from the magnesia carbon brick
composition as claimed in anyone of claims 1 to 9 comprising:
(i) providing mix of fused Magnesia and sintered sea water magnesia grains;
(ii) adding to the mix of step (i) above the Resin;
(iii) adding to the mix of step (ii) above the Graphite;
(iv) separately, a 'premix' is prepared by intimately mixing fine powders of
Aluminium, Boron carbide and sea water magnesia micro fines;
(v) adding to the mix of step (iii) above the Resin and Premix;
(vi) adding to the mix of step (v) above pitch powder, sintered sea water magnesia
fines and resin to obtain a final mix ;
(vi) subjecting the said final mix of step (v) above to steps of ageing, pressing,
curing and thereby obtaining the said brick.
11. Magnesia carbon brick obtained involving the composition as claimed in anyone of claims
1 to 10 comprising:



12. Magnesia carbon brick composition and Magnesia carbon bricks obtained thereof
substantially as herein described and illustrated with reference to the accompanying
examples.

The present invention relates to oxidation and corrosion resistant higher carbon containing
Magnesia carbon refractory brick composition and bricks produced thereof involving a new
dual antioxidant comprising aluminium and boron carbide and a process for manufacturing
these bricks. The Magnesia carbon refractory brick product according to the present
invention is fit for use as refractory lining of liquid steel processing vessels wherein
aluminium and born carbide content is optimized to ensure controlled spinel and glassy
phase formation to achieve desired higher oxidation resistance and thereby, favourably good
corrosion resistance towards steel making slag with good hot strength. The invented class of
Magnesia carbon refractory bricks are expected to perform better than conventional
Magnesia carbon bricks containing only one antioxidant (i.e. aluminium) in steel processing
vessels, particularly, steel ladles in a cost effective manner.