United States Patent Office
3,519,448
Patented July 7, 1970
1
2
3,519,448
Another object is to provide fused refractory materials
which exhibit low stoning and blistering and excellent
ZIRCONIA-ALUMINA FUSED REFRACTORY
MATERIALS AND STRUCTURES
Allen M. Alper and Robert N. McNally, Corning, N.Y.,
assignors to Corhart Refractories Company, Louisville,
Ky., a corporation of Delaware
No Drawing. Continuation-impart of application Ser. No.
643,337, June 5, 1967. This application Jan. 26, 1968,
Ser. No. 700,748
Int. Cl. C04b 35/48
10
US. Cl. 106—57
15 Claims
corrosion resistance when contacted by molten glass, and
structures made of such materials.
Another important purpose is to provide fused re
fractory material containing large crystals of zirconia and
in which often the formation of non-fragmented inter
locked zirconia crystal chains is promoted. Such a struc
ture, having a coarse microstructure of zirconia, tends to
retard stoning and has superior corrosion resistance.
In accordance with the present invention, it has now
been found that a fused refractory material satisfying the
above discussed and other desirable objectives comprises
ABSTRACT OF THE DISCLOSURE
primarily large zirconia crystals (and can also have dis
Fused refractory materials and structures of the zir 15 crete corundum or alpha alumina crystals and/or a sili
ceous glassy phase) and is composed essentially of the
conia-alumina type containing large zirconia crystals as
a primary phase. Composition consists essentially of,
analytically by weight: at least 50% ZrO2, 1 to 29%
following constituents, analytically by weight:
Al2O3,;0.1 to 25% SiO‘Z, 0.5 to 15% rare earth oxide, 0
to 6% P205, 0 to 5% alkaline earth oxide, 0 to 4% 20
alkali oxide, 0 to 47% Cr2O3, 0 to 25% FeO, ‘0 to 4%
ZrOz ________________________________ __ at least 50
A1203 _______________________________ __
1 to 29
halogen, and at least 90% of ZrO2 plus A1203 plus Si02
plus rare earth oxide plus Cr2O3 plus FeO plus halogen.
Structures useful in glass tanks exhibit corrosion, wear,
high temperature and thermal shock resistance and low
blistering and stoning.
Percent
Si02
______ _, ________________________ __
0.1 to 25
Rare earth oxides _____________________ __ 0.5 to 15
P205 _____________________________ __ up to about 6
Alkaline earth oxide ________________ __ up to about 5
25
Alkali metal oxide __________________ __ up to about 4
CROSS-REFERENCE TO RELATED
APPLICATION
This is a continuation-in-part of application Ser. No.
643,337, ?led June 5, 1967 now abandoned.
BACKGROUND OF THE INVENTION
Field of the invention
The present invention relates to fused refractory ma
terials and to articles produced from such materials. More
speci?cally, the invention is concerned with improved
fused refractory materials of the zirconia-alumina type
having particular value in glass tanks due to their excel
lent corrosion, wear, high temperature and thermal shock
resistance and low blistering and stoning.
In another embodiment of the invention, it has been
found that a further improvement in the corrosion resist
ance of the above described fused refractory materials
may be realized by the addition to the composition of
0.25 to 47%, and preferably 1 to 15%, of Cr2O3.
According to another embodiment, it has been found
that the density of the fused cast refractory materials of
the invention may be increased, the manufacturability may
be improved and the coloring of the glass contacting the
refractory may be slightly decreased by the addition to
the composition of 0.03 to 4%, and preferably 0.1 to
2%, of a halogen, preferably ?uorine. The bene?ts of the
halogen addition are derived whether or not the fused
refractory in which it is incorporated also contains the
Cr2O3 additive. The halogen helps to produce denser
castings.
As used herein, “rare earth oxide” means oxide of one
or more of the metallic rare earth elements having an
45 atomic number of 21, 39 and 57 through 71.
Description of the prior art
Of course, the fused material product will contain inci
Fused-cast refractory materials comprising substantial
amounts of alumina, zirconia and silica have previously
been disclosed in Japanese patent application 40,792/ 1960
of Oct. 10, 1960, published on Sept. 18, 1962 as publica
tion No. 14,348/1962. The application is entitled “Zir
conia-Alumina Type Cast Refractory Body” and was ?led
in the names of Hideo Nagashima, Eiji Miyake and Akira
Ito, as inventors.
dental impurities normally associated with the raw ma
terials. In some cases, such impurity constituents can be
in somewhat substantial amounts, or they may be deliber
ately added separately in such amounts. For example, iron
oxides (all computed as FeO) can amount to about 25 %,
especially in combination with amounts of Cr2O3. Thoria
(ThO2) is frequently present as a substantial constituent
of many rare earth oxide containing ores which may 'be
The materials disclosed in the published Japanese ap 55
found wanting in several respects. For example, in melting
high temperature glasses the prior materials have been
found to lack the necessary refractoriness, melting as they
fused refractory materials. It is permissible to include
?ne zirconia crystals included intragranularly in the
earth oxide plus Cr2O3 plus FeO plus halogen, which
plication are useful in many applications, but have been
used to provide the rare earth oxide content of the present
thoria in these fused materials in amounts up to about
5% (or even about 10%) by weight. In any event, the
do at from about l600° to 1750” C. The previously dis 60 new fused materials should consist essentially of at least
90% by weight of ZrO2 plus A1203 plus SiOz plus rare
closed materials also contain a large amount of extremely
limitation is applicable even in those situations where
certain ones of these constituents are absent.
ratio. Large amounts of ?ne zirconia particles lead to
Articles and structures produced from the described
problems of stoning and accelerate the corrosion rate of 65
fused refractory material may take any of the usual
the refractory.
forms, such as, fused cast articles, grain and rebonded
gram.
SUMMARY OF THE INVENTION
DESCRIPTION OF PREFERRED
The object of the present invention is to provide fused
EMBODIMENTS _
refractory materials characterized by excellent resistance 70
In a preferred embodiment, the fused refractory com
to corrosion, wear, high temperature and thermal shock,
position, without Cr2O3 or ?uorine additions, has the
and structures made of such materials.
alumina crystals as a result of the low zirconia/ alumina
3,519,448
4
following essential composition analytically on a weight
basis:
speci?cally “Norton Q-23 Zirconia,” the typical analysis
of which, on a weight basis, is as follows:
Percent
Zr02
________________________________ -. at least 60
Percent
ZrOz
___________________________________ -_ 85.03
A1203 ___________________________________ __
10.0
$102
____________________________________ __
4.36
Rare earth oxide _________________________ -. 1.5 to 9
Fe2O3 ___________________________________ __
P205 ____________________________ __ up to about 3.5
TiO2 ____________________________________ -_
Alkaline earth oxide _______________ -_ up to about 2.5
CaO ____________________________________ __
Alkali oxide ______________________ _. up to about 2.5 10
0.15
A1203
SiOz ___________________________________
___________________________________ ..~
__ 42 to
to 18
fractory materials is “Alcoa A-2” and is substantially
all A1203.
SiOZ plus rare earth oxide.
Some alkali oxide, e.g. N320, in an amount of 0.5 to
1.5% is helpful in decreasing the formation of blisters
in molten glass contacting the refractory material.
Where Cr2O3 is added, the material has the following
composition stated in broad and narrow, or more pre
ferred, ranges of each constituent, analytically on a
weight basis:
Narrow Range
ZrOz _________________________ .. 50% to 98% _____ _. 60% to 87.5%.
111203 _______ ._
S102 __________ ..
. 1% to 29% ______ __ 5% to 21%.
. 0.1% to 25%... _. 4% to 18%.
Rare earth oxide
105 _________ ..
. 0.5% to 15% _____ ._ .5% to 9.0%.
. Up to about 6%.. 1% to 3.5%.
Alkaline earth oxides
. Up to about 5%..- Up to about 2.5%.
Alkali oxides _________________ -_ Up to about 4%..-
0.28
The alumina employed in producing the fused-cast re
At least 93% of ZrO2 plus A1203 plus
Broad Range
0.18
Do.
FeO _____________________ .. Up to about 25%.. Up to about 7%.
C170; ________________________ .. 0.25% to 47% ____ ._ 1% to 15%.
Sum of ZrOz-l-AlgOz-l-SiOz-lz... At least 90% ____ .. At least 93%.
The monazite referred to in the subsequent descrip
tion and examples, unless otherwise noted, is Titanium
Alloy Co. monazite having the following typical analysis,
by weight:
About 60%-65% rare earth oxides and ThO2 as
follows:
20
Percent
CeO2 _____________________________ -_
La2O3 _____________________________ _.
Nd2O3 ____________________________ __
Th02 _____________________________ __
Y2O3 _____________________________ __
from 20 to 25
from 12 to 15
from 10 to 12
from 4 to 5
from 1.5 to 3
About
P205.
About 2% each of SiO;, and ZrO2.
The balance, minor amounts of A1203, F6203, MnO-2,
PbO, MgO, TiOz, CaO, CuO.
Another source of rare earth oxide which could be
used in producing the present materials is bastnesite
which is a rare earth ?uorcarbonate available in a num
Where ?uorine is added to the fused refractory ma
terial, the material has the following composition, stated
in broad and narrow, i.e. more preferred, ranges of each
constituent, analytically on a weight basis:
vBroad Range
Narrow Range
__ 60% to 89.4%.
.. 5% to 21%.
1’: 5
Alkaline earth oxide.
Alkali oxide.
Up to about 5%... Up60 about 2.5%.
. Up to about 4%..-
o.
Fluorine. ____________________ __ 0.03% to 4% _____ _. 0.1% to 2%.
Sum of ZrO2+Al2O3+SiOz+.... At least 00% ____ .. At least 93%.
ber of grades from Molybdenum Corp. of America. One
available leached concentrate of bastnesite has the fol
lowing general typical analysis:
Percent
Rare earth oxide ___________________ .__
Barium sulphate ______________________ _.
Calcium oxide _______________________ _-
68-73
1-3
0.3-0.5
sio2 ............................... --
0.3-0.5
Fluorine ____________________________ _.
5.0-5.0
ThO2 ____ __- ________________ __/ ______ __
less than 0.1
Fe2O3 ______________________________ -. less than 0.3
P205 _______________________________ _. less than 0.2
Loss on ignition ______________________ _.
20-21
The invention will be more fully appreciated in the
light of the following examples.
The present invention also contemplates refractory
structures including individual cast bricks, plates, slabs
or other shapes, and structures incorporating one or more
EXAMPLES 1-3
A batch of raw materials was prepared by mixing, by
weight, 80% zirconia (Norton Q-23), 10% alumina
(Alcoa A-2), and 10% monazite (Titanium Alloy Co.).
fused cast articles, such as refractory glass tanks, fur
naces, high temperature nozzles, for molten steel or high
The batch was melted and cast to form a brick. The re
temperature gases or the like, formed by one or a plu
in the following table.
Small slices of the Refractory A material 13/16" square
by %;” thick were then cut from the brick by diamond
rality of assembled fused cast articles.
The invention also contemplates the production of
grains of the fused refractory material and the formation
of articles from rebonded grains.
The materials of the invention are produced by mix
ing a batch of the necessary raw materials and melting
by any available technique as described, for example, in
US. Pat. 1,700,288 and US. Pat. 3,079,452.
As the basic raw materials for preparing the refrac
tories of the invention, it is preferred to use zirconia,
alumina and monazite. The last is a natural mineral hav
ing a substantial rare earth oxide content.
sulting fused cast brick is referred to as Refractory A
grinding and were polished, washed and oven dried at
110° C.
The specimens were tested for blistering in contact
with three di?’erent types of glass, (1) a borosilicate
glass, (2) a soda lime glass, and (3) a barium oxide glass.
A typical borosilicate glass used in the test has the fol
lowing cOmpOsitiOn on a percent by weight basis: 79.8%
K20
SiO2, and 0.8% B203,
CaO.
N320,
A1203.
A typical soda-lime glass used in the test has the
In the previosu description and in the claims, zirconia 70 following composition on a percent by weight basis:
refers to the pure compound. However, the commercial
73.4% SiO2, 16.72% NaZO, 0.12% potash, 4.96% CaO,
ly available zirconia generally contains substantial
3.30% MgO and 1.45% A1203.
amounts of alumina and silica. Therefore, in the fol
A typical barium oxide glass used in the test has
lowing description and examples, unless otherwise noted,
the following composition on a percent by weight basis:
the zirconia refers to a commercial zirconia source, 75 65.7% SiO2, 12.1% BaO, 6.7% NazO, 6.6% K20,
3,519,448
5
6
0.4% LizO, 0.4% RbZO, 3.4% A1203, 1.8% F, 0.6%
M1102 and
for varying periods of time. The amount of cut or re
.
duction in diameter of each specimen was then measured,
after removal from the melt. Measurements were taken
at two points on the sepcimen, one at the melt line,
i.e., the point on the specimen adjacent the air-glass
melt interface, and a second at a point mid-way be
tween the melt line and the end of the specimen which
has been submerged beneath the molten glass. The
smaller the cut, the greater is the corrosion resistance of
For purposes of comparison, specimens of an avail
able and commercially utilized zirconia-alumina fused
cast refractory were tested for blistering under the same
circumstances. The standard or comparison material is
a zirconia-alumina-silica refractory which is fully de
scribed in U.S. Pat. 3,132,953.
The standard refractory has the followling typical
analysis on a weight basis:
10
Percent
A1203 _____________________________________ __
49
SiO‘Z
ZI'203 ______________________________________
_____________________________________ __
15
NazO
_____________________________________ __
Fluorine
the refractory.
The composition of the barium oxide and soda-lime
glasses used in the tests are given above in connection
with Examples 1-3.
The barium silicate glass has the following composi
tion on a percent by weight basis: 63.5% SiOZ, 7.5%
1.5
NazO, 10.4% K20, 6.7% BaO, 4.5% CaO, 4.8% MgO,
3.8% A1203, 1.8% F, 0.5% TiO2, and 0.2% CeO2.
__________________________________ __ 0.2
Fe2O3, Tlog, B203 ______________________ __ Balance
The calcium-aluminum-boron silicate glass has the fol
lowing composition on a percent by weight basis: 54.5%
The standard or comparison material is referred to
as Refractory B in the following table.
The blister testing was carried out in the following
SiO2, 14.2% A1203, 17.5% CaO, 4.8% MgO, 7.7%
B203,
Na20+K20,
F6203,
‘and
0.1% ZrSiO4.
manner:
A 1" x l" x M?" sample having a highly ground sur
face, is pre-heated to 1400° C. for 15 minutes in the
The results of comparative tests are set forth in the
following data:
Extent of Cut, mm.
Temp.,
Example Number Ref.
A
B
Glass
° C. Time
Barium oxide ___________________ _ _
__
1, 550
7 days... _
1,550
__
o _____ _.
Mid-Point
. 98
0.1
1.42
1.05
1. 29
2. 80
0. 19
1. 30
A
B
2. 24
5. 00
0. 51
5. 00
A
B
1. 41
5. 00
0. 88
5. 00
A
B
____.do ___________ __
Melt Line
Barium silicate
furnace. Then the glass is added to the sample to wet
It will be seen from the above data that, in every
the surface with the borosilicate or other test glass. The 35 case, Refractory A, the material of this invention, ex
test is run at 1400° C. for an additional 15 minutes.
hibited very superior corrosion resistance, as compared
After the test is completed, the sample is rated by a
with Refractory B, the high alumina comparison re
direct visual comparison with a scale of ‘blistering
fractory.
standards.
‘
EXAMPLES 8-10
Blistering is the presence of bubbles in the re-solidi?ed
Refractory materials were then prepared as in Exam
glass due to interaction of the molten glass at the inter
ples l-3, but varying the content of monazite to 15%
face With the refractory. Blistering may be rated in a
in one batch and 5% in another. The amount of alumina
number of ways, but the system here used is based on
was adjusted to compensate for the change in monazite
direct visual comparison with a scale of blistering
content.
Refractories were prepared from each batch
standards. The standards are based on bubble popula 45
as before and were compared with the standard Re
tion and size.
fractory B for corrosion resistance. Refractory C has a
The standards were established after numerous tests
composition of, by weight, 80% zirconia, 15% alumina
by arbitrarily assigning a 100 (no unit) value to the
and 5% monazite. Refractory D has a composition of,
by weight, 80% zirconia, 5% alumina and 15% mona
greatest amount of blistering observed. An absence of
blistering is considered to be a zero value. On this basis.
the tests reported below were arranged, compared, and
assigned proportionate ratings.
zite. Refractory D—l has a composition of, by weight,
60% zirconia, 20% alumina and 20% monazite.
-
In the present instance, the following blister ratings
were observed with the refractory of this invention,
Refractory A, and the comparison material, identi?ed as
Refractory B:
Example No.
Refractory Glass
Borosilicate _ _ _
Temp.,
55
Blister Rating
Ex. N0. Ref.
Glass
° 0.
Time,
Extent of Cut, mm.
hrs. Melt Line
Mid-point
8 _____ __ B
9 _____ ._ 0
Soda-lime.
...__do__._
1,538
1, 538
72
72
2.60
1.67
0.56
0. 40
10 . . _ _ _ .
_ . _ "do..."
1, 538
72
5.00
5.00
"do..."
1, 538
72
2. 50
0.62
10(a).._. D~1
16
Soda-lime_ __ __
12
Barium oxide _
14
It is apparent from the above that the present re
fractory provides a substantial reduction in Blister Rat
ing, on the order of 50%, in comparison with the
standard zirconia-alumina refractory.
60
Thus, the results of Examples 8-101 indicate that a
combination of lower alumina content and a monazite
content of 15% or above reduces the corrosion resistance
to molten soda-lime glass of the prosent refractories below
that of the standard Refractory B. However, Example
10(a) shows that the higher monazite content can be
employed with the higher alumina content to provide re
sistance to soda-lime glass corrosion. For soda-lime glass
service, it is de?nitely desirable to have at least 15 wt.
percent Al2O3 when the new refractory material contains
EXAMPLES 4—7
Specimens of the Refractory A of the invention were 70 about 9 wt. percent or more of rare earth oxide derived
from monazite. In service with other glasses having a
prepared as in Examples 1-3 and were compared for
substantial alumina content, the new refractory material
corrosion resistance with standard or comparison Re~
having lower alumina combined with higher monazite
provides much better resistance to corrosion.
suspended in melts of glasses of different compositions 75 Another factor indicated by the results of Examples
fractory B.
Elongated specimens of the Refractories A and B were
3,519,448
7
8
8-10 is that a reduction of the monazite content to 5%
The results, after contact with a soda-lime glass for
72 hrs. at 1538° C., are shown in the following data:
with corresponding increase in the alumina content pro
vides improved corrosion resistance.
Extent of Cut,
Refractory mm. Melt Line
Example Number
EXAMPLES 11-16
Additional refractories were prepared as in Examples
18.
1-3, but varying the weight proportions as set forth below:
J
Zireonia, Alumina, Monazite,
percent
percent
percent
Refractory E _____________________ __
62
30
Refractory F. _ _
._
53
40
7
Refractory G._
__
44
50
8
6
Refractory H _____________________ _ .
35. 5
60
4. 5
Specimens of each refractory were then immersed in
molten soda-lime glass at 1538° C. for 72 hours to observe
Stones
5. 00
10
Man .
5. 00
2. 77
5.00
Do.
Do.
Do.
5.00
Do.
EXAMPLES 21-27
Additional refractories were prepared and were com
pared with the standard Refractory B. The specimens were
contacted with molten soda-lime glass at 1538° C. for 72
hours. The results are shown in the following data:
Refractory Composition, wt. percent
Zirconia-Alumina-llionazrte
Extend of Cut, mm.
Example
(Norton
Number
Q-23)
(Alcoa
A-2)
(Titanium
Alloy Co.) Melt Line
Refractory B
80
71
80
90
10
20
10
5
10
9
10
5
90
5
(1)
80
15
5
Mid-Point
Stones
3. 02
0. 62 Many.
2. 21
1. 79
2. 42
2. 25
0. 51 None.
0. 32
Do.
0.72
D0.
0. 56
D0.
1. 95 ............ _.
Do.
2. 27
Do.
0.75
15% REO.
corrosion resistance and stoning. In the present context,
stoning refers to the presence of inclusions in the resolidi
?ed glass after a melt of the glass has contacted the re
It is seen from the above data that substantial improve
ment in corrosion resistance and absence of stoning are
experienced with the materials of this invention.
As already discussed brie?y above, in one embodiment
of the invention Cr2O3 is added to the basic refractory
composition to improve corrosion resistance. This has
conact. Refractories causing the formation of stones are
particular utility in structures which contact molten cal
of course undersirable for use as glass tanks or other
cium-alumina-boron-silicate glasses. Standard chrome
structures which contact molten glass, since they impart
undesirable properties to the glass product.
35 bricks, conventionally used in glass tanks, crack in contact
with such glasses. The following examples illustrate the
Comparisons were made with the standard Refractory
improvement in corrosion resistance experienced as a
B and the results are reported in the following data:
result of the Cr2O3 addition to the present refractories.
fractory. In this case the stones are attributable to inter
action with the refractory with which the glass is in
Example Number
Refractory
Extent of Cut,
mm. Melt Line
Stones
1. 84 None.
2. 63 Many.
0 Do.
EXAMPLES 28-29
A refractory batch was prepared by mixing, by weight,
7
.
80% zirconia, 10% alumina and 10% monazite. The
8
1
Do.
batch was melted and cast to form a refractory block
from which specimens were cut. A second refractory batch
As the zirconia content is decreased progressively in 45 was prepared by mixing, by weight, 80% zirconia, 6%
alumina, 10% monazite and 4% Cr2O3, and this batch
refractories B through H, the presence of many stones is
was also melted, cast and cut to provide specimens.
found on observation of the re-solidi?ed glass from the
The specimens were then immersed in a molten cal
melts which have been in contact with the refractory.
cium-alumina-boron silicate glass bath at 1'538" C. for 96
In Example 11, Refractory E contains 62% zirconia
hours. The composition of the glass was the same as that
(Norton Q-23) which contains about 85% ZrO2. Thus,
used in Example 7.
Refractory E contains about 53% ZrO2 and is free from
stoning. However, in Example 12, Refractory F contains
The results are set forth below:
53% zirconia (Norton Q-23) or about 45% ZrO2 and
produces many stones in the glass which it contacts. In
Examples 14 and 15, stoning also results as the ZrO2 con
tent is reduced farther below 50% in Refractories G and
H. Therefore, in accordance with the invention the re
fractories must contain at least 50% ZrOz to minimize
Extent of Cut, mm.
Example Number
Refractory
Melt Line
Mid-Point
28 __________________________ __ Without Cr2O3__
1. 68
0. 91
29 __________________________ __ With CHO; ____ __
0.51
0.56
the problem of stoning. Stoning is also found in the glass
contacted by Refractory B, under the same conditions, as 60
shown in Examples 13 and 16.
As seen above, the Cr2O3 addition results in improved
corrosion resistance both at the melt line and at the
EXAMPLES 17-20
mid-point. Not only are the present refractories free from
Likewise, it has been established that low zirconia and
cracking which occurs in standard chrome bricks when
alumina contents, in a constant ratio, and high rare earth
used with such glasses, but the cost is considerably below
oxide and P205 contents, obtained by increasing the
that of the standard chrome refractory.
monazite content results in refractories having poor cor
EXAMPLES 30-31
rosion resistance and high stoning.
Refractories were prepared as in Examples l-3, varying
The effect of the Cr2O3 addition to the refractories of
the weight proportions as follows:
this invention was also observed in contact with molten
Refractory
Zircorria, Alumina,
percent
percent
20
30
40
20
30
40
Monazite,
percent
60
40
20
soda-lime glass for 72 hours at 1538° C. Fused-cast re
fractories were prepared from batches containing, by
weight, 80% zirconia, 10% monazite, 8% alumina and
2% Cr2O3, and 80% zirconia, 10% monazite, 4% alumina
75 and 6% Cr2O3.
3,519,448
9
Specimens of the two refractories were immersed in
the molten glass and the results appear below:
The Q-l Zr02 material had the following typical
analysis, by weight: 96.15% ZrO2 (including about 2%
Extent of Cut, mm.
Example Number
Refractory
HfOZ), 1.0% max. A1203, 0.8% max. SiO2, 0.75% max.
CaO and 0.5% max. Fe2O3.
EXAMPLES 40-43
The present refractories also exhibit relatively low
Melt Line Mid-Point
30 __________________________ ._ With 2% CrzO;_.
31 __________________________ ._ With 6% CD03"
2. 36
2.18
10
greater or an equivalent rare earth oxide content of about
2% or greater is desirable.
0. 72
0.47
Thus, the increase in Cr2O3 content at the expense of
alumina is seen to improve the corrosion resistance of the 10 exudation. Exudation testing was conducted to measure
the quantity of glassy phase exuded from the refractory
refractory.
when heated. The test was carried out in the following
The bene?t of the addition of from 0.03 to 4% and
preferably from 0.1 to 2% of a halogen, especially ?uorine,
is demonstrated in the following examples. The halogen
manner:
metal halides for this purpose include CaF2, AlFg, MgF2,
nique of weighing the sample in water, before and after
the heat treatment, the amount of glassy phase lost is
A 1" x 1" x 1As" highly ground sample is placed on a
may conveniently be added as a metal halide. Suitable 15 platinum sheet at 1500° C. for 16 hours. Using a tech
BaFz, SrF2, NaF, CaCl2, MgCl2, NaCl, KCI, NaI, KI,
measured in terms of the percent change in volume of the
NaBr, and KBr.
sample.
EXAMPLE 32
A refractory batch was prepared by mixing, by weight,
76.8% zirconia, 9.6% alumina, 9.6% monazite and 4%
20
A1133. The batch was melted, cast and specimens were
cut from the casting.
On contact with molten borosilicate glass, the refrac
tory exhibited a Blister Rating of 8-12 which compares
very favorably with the Blister Rating of 38 for standard
zirconia-alumina Refractory B and is equivalent to the
Two refractory compositions prepared in accordance
with the invention were compared with standard Refrac
tory B in exudation tests. The results with Refractory B,
Examples 40 and 41, and the results with the other re
fractories, Examples 42 and 43, are reported in the fol
lowing table. The refractory of Example 42 contained,
by weight, 80% zirconia (Norton Q-23), 10% alumina
and 10% monazite (Titanium Alloy Co.). The refractory
of Example 43 contained, by weight, 76.8% zirconia
(Norton Q-23), 9.6% alumina, 9.6% monazite (Titanium
Alloy Co.) and 4.0% AlF3.
Blister Rating for a refractory of, by weight, 80% zir
conia, 10% alumina and 10% monazite.
Also, in corrosion testing in contact with a soda-lime
glass the resistance was found to be equivalent to the
TABLE
80% zirconia—10/a1umina-10% monazite refractory, with
Exudation Test (16 hrs. at 1.500° C.)
out a halogen addition. No stoning is observed in the
Percent
glass in contact with the halogen containing refractory.
Before
Thus, the addition of a halogen in the stated propor
tions to the refractories of this invention does not effect
their superior corrosion resistance and low stoning and
After
Diff.
Change
Example 40:
blistering, and has been observed to improve the density,
microstructure and manufacturability of the refractories.
EXAMPLES 33-39
The present materials also have good thermal shock
resistance. This property was tested in the following
manner:
A 1" x 1" x 3" sample is heated from room tempera
ture to 1400" C., held for 10 minutes at that temperature
and then cooled rapidly at room temperature. This con
stitutes one complete cycle. After each cycle, the sample
is examined for cracking and spalling of small pieces. r
When the sample has spalled, the test is stopped and the
number of cycles is recorded.
Any sample which lasts over about 5 cycles is con
From the above, it can ‘be seen that the percent change
in volume of the standard Refractory B, tested in Ex
sidered to have good thermal shock resistance in the
1400° C. test. In a similar test conducted up to 1650" C., 55 amples 40 and 41 is on the order of 10%. The low exuda
tion of the materials of this invention, Examples 42 and
survival for 4 or more cycles is considered evidence of
43, is evidenced by a volume change of only 3.0% and
1.0% respectively.
good thermal shock resistance.
The results of several such tests are reported in the
following table.
EXAMPLES 44-46
TABLE
Ex.
No.
Refractory Composition Tested, weight
percent
1,400° C.,
1,650° 0.,
Cycles
Cycles
No. of
Using a substantial amount of zircon, (zirconium
silicate) as a raw material the following two high silica
refractory compositions were prepared on a weight basis
No. of -
as follows:
33__._ 80% Q-l Zl‘Oz, 10% A1203, 10% Monazite__
19,10 __________ _.
34---- 80% Q-23 ZrOz,10% A1203,10% Monazite_.._.
.._
8, 0
35.--. 80% African ZrO2, 10% A1203, 10%..
__
5
65
Monazite.
36.-.- 76.0% Q-23 ZrOz, 9.5% A1203, 9.5% __________ _.
Monazite, 5.0% NazO.
37.... 80% Q-23 ZrOz, 19.5% A1203, 0.5% __________ ..
Monazi
3
.
38.... 80% Q-23 Z1‘O2,
Monazite.
39.... 80% Q-23 ZrOz,
Monazite.
18%
A1203,
2.0% .......... ..
2
Monazite _____________________________ ._
15%
A1203,
5.0% __________ __
Example 44,
Example 45,
Percent
Percent
38. 6
9. 7
48. 2
2. 5
37. 8
9. 5
47. 3
2. 4
1. 0
3. 0
4
10
The refractories were tested in contact with a soda-lime
glass to determine corrosion resistance and stoning, in
Where thermal shock resistance is important, the above
comparison with a sample of standard refractory B. The
data indicates that a monazite content of about 5% or 75 samples were in contact with the soda-lime glass for three
3,519,448
11
12
at least 90% of ZrO2 plus A1203 plus Si02 plus rare earth
days at 1538° C. The composition of the soda-lime glass
oxide plus FeO plus Cr2O3.
is given above. The results, set forth in the following
table, indicate the superior corrosion resistance and lower
9. The fused refractory material of claim 8 wherein
stoning of the high silica refractories of the invention, Ex
the P205 is at least 1% by Weight.
amples
tor
B 44 and 45, as compared with the standard refrac 5
10. The fused refractory material of claim 9 wherein
y
'
the alkali oxide is at least 0.5% by weight.
TABLE
Refractory
Composition
Extent of Cuts, mm.
Melt Line
Mid-Point
Average
2. 77
0. 38
1. 58
Example 44 _____ __
Stoning
Temp., days
Few _____ ._ 1,538° 0., 3 days.
Example 46 _____ __
1.56
0.36
0.96
Few _____ __
D0.
Example 46 l ____ __
3.93
2. O4
2. 99
Many. __-_
Do.
1 Standard Refractory B.
11. The fused refractory material of claim 9 wherein
the P205 is at least 1% by weight and the alkali oxide is
at least 0.5% by weight.
12. The fused refractory material of claim 1 wherein
made in the procedures and products Without departing
from the scope of the invention as de?ned in the follow 20 said material consists essentially of the following consti
tuents, analytically on a weight basis:
ing claims.
What is claimed is:
60% to 87.5% ZrO2,
1. A fused refractory material comprising primarily
5% to 21% A1203,
crystalline zirconia, said material consisting essentially
to 18% SiOZ,
of the following constituents analytically, on a weight 25 4%
1.5% to 9% rare earth oxide,
basis:
1% to 3.5% P205,
up to about 2.5 % alkaline earth oxide,
at least 50% ZrO2,
up to about 2.5 % alkali oxide,
1% to 29% A1203,
0.1% to 25% SiO-Z,
30 up to about 7% FeO,
1% to 15% C1303, and
0.5 to 15% rare earth oxide,
Although the present invention has been described with
reference to certain preferred embodiments, it will be
understood that various changes and modi?cations may be
up to
P205,
up to 5% alkaline earth oxide,
up to 4% alkali metal oxide,
up to 47% Cr2O3,
up to 25% FeO,
up to 4% halogen, and
at least 93% of ZrO2 plus A1203 plus SiO-z plus rare earth
oxide plus FcO plus C1'2O3.
13. The fused refractory material of claim 1 wherein
35 said material consists essentially of the following con
stituents, analytically on a Weight basis:
50% to 98% ZrO2,
1% to 29% A1203,
0.1% to 25% SiO2,
at least 90% of ZrO2 plus A1203 plus SiOz plus rare earth
oxide plus Cr2O3 plus FeO plus halogen.
2. The fused refractory material of claim 1 containing
at least 0.25% by weight Cr2O3.
3. The fused refractory material of claim 1 containing
at least 0.03% by weight halogen.
4. The fused refractory material of claim 1 wherein
said material consists essentially of the following constitu~
0.5 to 15% rare earth oxide,
up to about 6% P205,
up to about 5% alkaline earth oxide,
up to about 4% alkali oxide,
0.03% to 4% ?uorine, and
at least 90% of ZrO2 plus A1203 plus SiOz plus rare earth
oxide plus ?uorine.
ents, analytically on a ‘weight basis:
at least 60% ZrO2,
2% to 21% A1203,
4% to 18% SiO2,
14. The fused refractroy material of claim 13 wherein
the P205 is at least 1% by weight.
15. The fused refractory material of claim 1 wherein
said material consists essentially of the following constitu
1.5% to 9% rare earth oxide,
up to about 3.5% P205,
up to about 2.5% alkaline earth oxide,
up to about 2.5 % alkali metal oxide, and
ents, analytically on a weight basis:
60% to 89.4% ZrO2,
5% to 21% A1203,
at least 93% of ZrO2 plus A1203 plus SiO2 plus rare earth
4% to 18% SiOZ,
oxide.
5. The fused refractory material of claim 4 wherein the
P205 is at least 1% by weight.
6. The fused refractory material of claim 4 wherein the
1.5 % to 9% rare earth oxide,
1% t0
P205,
up to about 2.5 % alkaline earth oxide,
up to about 2.5% alkali oxide,
alkali oxide is at least 0.5% by weight.
60 0.1% to 2% ?uorine, and
7. The fused refractory material of claim 4 wherein
at least 93% of ZrO2 plus A1203 plus SiO2 plus rare earth
the P205 is at least 1% by weight and the alkali oxide
oxide plus ?uorine.
content is at least 0.5% by weight.
8. The fused refractory material of claim 1 wherein
References Cited
said material consists essentially of the following con—
UNITED
STATES PATENTS
stituents, analytically on a weight basis:
3,132,953
5/1964 Alper et a1. ________ __ 106-57
50% to 98% ZrOZ,
1% t0
A1203,
FOREIGN PATENTS
0.1% to 25% SiO2,
0.5% to 15 % rare earth oxide,
up to about 6% P205,
up to about 5% alkaline earth oxide,
up to about 4% alkali oxide,
up to about 25 % FeO,
0.25 % to 47% Cr2O3, and
70
14,348
9/1962 Japan.
JAMES E. POER, Primary Examiner
US. Cl. X.R.
75 l06--66