Note: Descriptions are shown in the official language in which they were submitted.
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1 m e present invention relates to an alloy for
a nozzle plate for spinning glass fibers~ and particularly
to an alloy by the use of which there can be manufactured
a flat plate shaped bushing nozzle which is substantially
free from wetting by molten glass and enabling formation
of a very large number of nozzle holes per unit area.
Representative of conventional nozzle plates
for producing glass fibers is a flat nozzle plate made of
a platinum-rhodium alloy. This flat nozzle plate is
manufactured by simply machining nozzle holes from about
1.5 to about 3 ~n. in diameter in a flat plate made of
a platlnum-rhodium alloy. In this flat nozzle plate made
of a platinum-rhodium alloy, the contact angle between
the nozzle plate and the molten glass is small, namely,
the nozzle plate is wetted heavily by the molten glass.
After the appearance of this flat nozzle plate, there
was developed a nozzle plate made of a platinum-gold-
rhodium alloy in which the contact angle between the
nozzle plate and the molten glass is larger than that
of the former nozzle plate, thus the nozzle plate is
wetted by the molten glass to a lesser extent than in
the former nozzle plate. However, in both of the two
types of nozzle plates described above there is still
encountered a problem. When a pitch for the nozzle holes
is made narrower and lf one of the filaments flowing
through the nozzle holes is cut, the molten glass bead
formed by the molten glass which has passed through the
nozzle hole tends to spread over a large area of the
surface Or the nozzle plate, and thus cuts the other
filaments rlowing through the nozzle holes ad~acent to
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1 the nozzle hole for said first cut filament. This adverse
phenomenon spreads in the manner of a chain reaction, with
the result that all the filaments are cut, and the surface
of the nozzle plate is covered with molten glass which has
passed through the nozzle holes. Once this situation has
been established, it becomes very difficult to separate
each filament from the combined bead of molten glass, that
is~ to bring back the original state in which the filament
of molten glass discharged from one nozzle hole flows
10 smoothly and separately without disturbing the molten -
glass discharged from the other nozzle holes, whereby all
o~' the ~:Ilaments of the molten glass dlscharged from each
lndiv:Ldual nozzLe hole f'orm independently flowing flla-
ments. Particularly, in cases where there is used a pitch
f'or the nozzle holes of 5 mm. or less, even a skilled
operator cannot maintain independent flows of filament by
the use of conventional methods whereby each filament is
succesively formed through respective nozzles. ~urther,
the platlnum-gold-rhodium alloy is brittle, and is
inferior both in durability and machlnability. ~`or
lnstance, lt was found that a nozzle plate made of the
alloy and havlng about 50 nozzle holes per square
centimeter was bent outwardly and deformed after a long
perlod of use. And a nozzle plate made of the above alloy
25 and having 1000 or more nozzle holes needed reinf'orcing ~ -
ribs for preventing deformation. In this case there
were problems when forming the relnforcing ribs by welding,
small cracks occurred on account of thermal expansion, and
these small internal cracks were furGher enlarged by
mechanical shocks and/or by thermal expansion and
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1 contraction resultlng in leakage of the molten glass~
The reason for these drawbac:ks is that gold and
rhodium show very low solid solubility wlth each other and
the larger the amount of gold or rhodiLum, the more diffi-
cult it is to form a single complete solid solution.
It has been pointed out that , in
the platinum-gold-rhodium system, the resistance to wet-
ting by the molten glass filament increases when the
alloy contains gold in an amount between 3 and ll per cent
by weight which is near the solid solubility limit ror
gold consequently, it is considered to be the erfect Or
gold which is very much less soluble in a pla~inum~rhodium base
alloy in the solid state. In view o~ the situation
described above, it has been generally accepted that
it is rairly difficult to produce a single complete
solid solution which a~fords both an excellent reslstance
to wetting by molten glass and a superior machinability.
A nozzle plate made Or graphite or boron nitride 1s
superior to the above described nozzle plates made of
alloys in terms Or the resistance to wettin~ by the
molten riber glass. However, a nozzle plate made of
graphite cannot be used in air since the graphite is -
liable to be oxidized. And with a nozzle plate made Or .
boron nitride it is di~ficult to atkaln a uni~orm
temperature distribution because the boron nitride is an
insulator. A nozzle plate made Or boron nitride also has
a disadvantage that the contact angle between the nozzle
plate and the molten glass is apt to vary depending upon
the state o~ the surrace rinish of the nozzle plate.
An ob~ect Or the present lnvention ls t~D provide
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1 an alloy for a nozzle plate for spinning glass fibers
whlch has an excellent resistance to wettin~ by molten
glass, a superior machinability and a ~superior durability.
Another ob~ect Or the present inventlon is to
provide an alloy for a nozzle plate for spinning glass
fibers by the use of which there can be manufactured a
nozzle plate in which a pitch for nozzle holes of 2 mm. or
less can be used, and a large number o~ no~zle holes can
be machined in the nozzle plate.
Still another ob;ect o~ the present invention
is to provide an alloy for a nozzle plate ~or spinning
glass ribers by the use of which there can be manufactured
a nozzle plate to which reinrorcing plates can be welded
readily, and which can be used for a long period of time.
In the course of research and development of
the present invention, research was conducted to obtain
a material for manufacturing nozzle plates, which is free
from wetting by molten glass, or is hardly wetted by the
molten glass, and also has a superior machlnability,
and with the use o~ which there can be manuractured a
nozzle plate having an increased number of nozzle holes.
It was made possible, in accordance with the present
invention and by the use of a platinum-gold-palladium -
system alloy, to manufacture a nozzle plate which is
able to have several thousand nozzle holes having
therein a pitch Or 2 mm. or less, and which can be used
ror a long period of time due to the fact that reinforcing
plates can be readily welded to the nozzle plate. In
startin~ the research, consideration was given to the
racts that gold-palladium system binary alloys f~rm
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complete solid solu ions. It was also observed during the course
of the research that, in a nozzle plate made of an alloy containing
80 per cent by weight gold and 20 per cent by weight palladium
the contact angle between the alloy and the molten glass has a
large value of 80 degrees, and that the nozzle plate made of the
above binary alloy still tends to melt when used for spinning
glass fibers, hecause the above alloy has a low melting point of
about 1380C.
It was gathered through careful consideration that
platinum-gold-palladium system alloys should form a solid solution
more readily than platinum-gold-rhodium system alloys, and the
contact angles between the alloy system and the molten glass might
be substantially equal to the contact angles between the
platlnum-gold-rhodium system alloys and molten glass, and further,
that the alloy should have superior workability and durability.
As the result of the research, it was found that an alloy
consisting essentially of between 82 and 9~ per cent by weight
platinum, between 3 and 10 per cent by weight gold, and be~ween
3 and 12 per cent by weight palladium forms a single complete
20 solid solution, and has an excellent resistance to wett.ing by ~.
molten glass and a superior machinability, and a nozzle plate . .
made of the above alloy has a superior durability.
The present invention, in one aspect, resides in a single ~.
piece nozzle plate adapted for spinning glass fibers, said
nozzle plate being made of an alloy consisting ess~ntially of .
between 82 and 92 percent by weight platinum, between 3 and 10%
by weight gold and between 3 and 12% by weight palladium, said
alloy having excellent resistance to wetting by molten glass;
the plate having a predetermined number of nozzle holes at a . :
~0 predetermined pitch, and further being characterized by having
a high orifice density per given unit area of said plate. .:
In another aspect the invention resides in a method
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for making a nozzle plate for spinning glass fibers comprising
the steps of (a) preparing a flat nozzle plate blank made of a
Pt-Au-Pd ternary alloy consisting essentially of between 82
and 92 percent by weight platinum, between 3 and 10 percent by
weight gold, and between 3 and 12 percent by weight palladium
and (b) forming a required number of nozzle holes at a predeter-
mined pitch in the plate.
In the alloy employed in making the nozzle plate according
to the present invention having the chemical composition
described above, the resistance to wetting by molten glass
increases with the increased content of gold. The rate of
increase in the contact angle between the above alloy and the
molten
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1 glass, however, becomes less with the lncrease in gold
content, and gradually close to a fixed limit Yalue,
while the melting point Or the alloy becomes gradually
lowe~ thus the amount of the evaporation of gold during
the high temperature operation increases disadvankageously.
If the alloy contains gold in an amount exceeding the
aforesaid maximum limit, the machinability is degraded
and such undesirable defects as cracking take place to
make the nozzle plate unusable.
On the other hand, if the palladium content is
increased, the machinability is improved and the
resistance to wetting is decreased. The ratio Or the
palladium content to the gold content has a great
influence on the resistance to wetting and machinability.
When the gold content is large and the palladium content
is small, the resistance to wetting is improved and the
machinability is degraded. And when the palladium
content is large and the gold content is small,
machinability is improved and the resistance to wetting
ls degraded.
me smaller is ths amount of platinum contained
in the all~ , the lower is the melting point of the
platinum alloy. However, m the present lnvention, no problem
arises in the performance of the nozzle plate as long as
the platinum content of the alloy remains within the
specified range. Taking all of the above described
racts into consideration, it can be said that, in
platinum-gold-rhodium alloys, rhodium and gold are only
soluble wlth di~ficulty in each other in the solid state 3
and even in platinum-gold system alloys, the solid
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1 solubility limit for gold is about 4 per cent, These
facts lead to the conclusion that, in the case Or the
above alloys, solid solution alloys are obtained only
with difficulty. It can ~lso be said that, in the above
alloys, the machinability is degraded because the crystal
grains grow fast and become coarse readily.
By con~.rast, in the platinum-gold-palladium
system alloy employed in the n~zzle plate of the present invention, both
the platinum-palladium system and the gold-palladium
system form continuous complete solid solutions, and
the palladium plays a role of dissolving the platinum in
the gold in the solid state and vice versa, with the
result that complete solid solution type alloys are
obtained with great ease and the machinabillty is enhanced.
Hereinafter the present invention will be
explained with reference to the embodiments thereo~.
Embodiment l.
An alloy containing 90 per cent by weight
platinum, 5 per cent by weight gold, and 5 per cent by
weight palladium was melted under vacuum in an alumina
crucible to produce an ingot. A nozzle plate was made
by rolling the ingot weighing 12~0 g. into a nozzle plate
blank of 2 mm. thick, and machining 4000 nozzle holes
in the nozzle plate blank having a nozzle hole density
of 34 nozzle holes per square centimeter.
No cracking occurred during the processing.
&lass fibers were spun with the use of this nozzle
plate, and it was round that this nozzle plate can be
used continuously ror a period o~ time of 3 months or more.
A publicly known alloy containing 85.5 per cent
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1 by weight platinum, 9.5 per cenk by weight rhodium, and
5 per cent by welght gold was melted ~mder vacuum in
an alumina crucible to produce an ingot. A nozzle plate
blank was manufactured by rolling the ingot weighing
1200 g. to a $hickness of 2 mm. However, small cracks
were formed in the nozzle plate blank during the rolling
operation, and thus it was impossible to use the nozzle
plate blank until it was repaired.
or these cracks, the visible ones were repaired
by welding all the sur~aces Or the nozzle plate. However,
lnvlsible cracks deep ln the nozzle plate were propagated
by the expansion and contraction Or the nozzle plate due
to temperature changes during the operation, resulting
in a leakage of the molten glass. It was thus impossible
to prepare a practical nozzle plate having 800 or more
nozzle holes~
Embodiment 2.
Three flat nozzle plates were manufactured Or
three different alloys according to the present invention,
which had three dirferent chemical compositlons, and
measurements were taken o~ the contact angles between the
above flat nozzle plates and molten glass at temperatures
in the range from 1100C. The results are giYen in the
table below in comparison with the contact angle between
a nozzle plate made of the publicly known platinum-
rhodium-gold system alloy and the above molten glass.
In the table, the specimen No. 4 is an alloy containing
platinum in an amount below the range used in the present
invention and gold in an amount exceeding the above
range.
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Alloy Composition (% by weight) Contact
No. ; Pt Rh Pd Au Angle .:
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1 go _ 5 5 72 - 77
2 85 _ 10 5 60 - 65
3 85 _ 6 ~ 73 - 78
4 80 _ 8 12 75 - 80
a5 5 9.5 _ 5 76 - 81
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1 As can be seen from the table, the contact angles between :.
the nozzle plates made of the alloys of the present
i.nventi.on and molten glass are substantia:l.ly equal to :
the contact angle between the nozzle plate rnade O r the
5 publicly known platinum-rhodium-gold alloy and the molten
glass, while the nozzle plates made of the alloys of the
present invention showed excellent machinability and
superior nozzle plate performance, as was the case with
Embodiment 1.
In this connection, it should be recalled that
the contact angle between a nozzle plate made of an alloy
contalning 80 per cent by weigh~ gold and 20 per cent by
welght palladium and the molten glass is in the range
from 81 to 86 degrees, and the contact angle between a
15 nozzle plate made of an alloy containing 60 per cent by
weight gold and 40 per cent by weight palladium and
the molten glass is in the range from 51 to 57 degrees.
~s has been described in detail in the foregoing, ~:
the alloy according to the present invention has an
excellent resistance to wetting by the molten glass and
an improved machinability, and due to these feat;ures
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1 en~oys advantages that a nozzle plate can be manufactured
very readily by the use of the alloy of the present
invention because no small cracks are formed in the
nozzle plate during the processing and an increased
number of nozzle holes can be machined with ease in the
nozzle plate, and that the nozzle plate made of the alloy
of the present invention can be used for a longer period
of use for spinning glass fibers.
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