[0001] The present invention relates to an apparatus for chill casting of metallic materials.
[0002] Extraction of filaments from a liquid melt has been employed to form amorphous metal
filaments. For example, the US-A-3 863 700 discloses a method and apparatus for filament
extraction from molten metal contained in a vessel. This patent offers no teaching
which overcomes the problem of reaction of the melt with the vessel containing the
melt when either
[0003] a high melting or a reactive material is employed. Alloys containing large concentrations
of titanium, zirconium, niobium, vanadium, chromium, and the like, when molten are
known to react with refractory crucible materials such as alumina, fused silica, zirconia,
thoria, yttria, beryllia, and the like. Reaction with the crucible can cause: contamination
of the melt which can result in embrittlement of the cast filament; formation of insoluble
inclusions in the melt which can reduce the fluidity of the melt, and thereby changing
its casting characteristics; and attach of the crucible by the melt which will shorten
the life of the crucible.
[0004] By the appropriate selection of the crucible material employed with a particular
alloy, the abovementioned problems can be minimized but not eliminated. The selection
process may require extensive experimentation to determine the compatible combinations
of alloy and crucible material. In many cases the crucible material that is subject
to minimal attack by the alloy may suffer from thermal instability and be subject
to cracking when thermally cycled.
[0005] High temperature nickel-base, nickel- chromium-titanium-aluminum alloys have been
melted in water-cooled copper crucibles. GB-A-1 517 283 teaches the use of a water-cooled
crucible to contain nickel-based alloys. The melt is removed from the crucible by
spinning the crucible about its axis to generate atomized particles of liquid which
move out radially from the edge of the crucible. This patent offers no teaching that
the melt can be extracted from the crucible in the form of a continuous stream of
limited dimensions.
[0006] Likewise, GB-A-1 428691 teaches that alloys can be melted in water-cooled molds.
The melt is then solidified in situ. This patent offers no teaching of a technique
for the extraction of liquid metal from a water-cooled mold.
[0007] Since the electrodes used to supply heat to the melts in the above examples are directly
above the melt, it is necessary to form a stream of controlled dimensions away from
these electrodes if a filament of metal is to be extracted. Thus, while the above
examples show a method for melting materails in water-cooled crucibles, they provide
no teachings which are suitable for extraction of filaments from the liquid melt.
[0008] The most relevant DE-A-2 827 731 discloses an apparatus for the extraction of filaments
from a metallic melt having a tiltable crucible. But also this patent publication
offers no teaching to overcome the problem of reaction of the melt when either a high
melting or a reactive material is used.
[0009] Finally there is made reference to the EP-A-0 055 827 having the same priority. Thus,
the objective of the invention was to provide an apparatus for chill casting of high
temperature and/or reactive metallic materials. More particularly, the objective related
to an apparatus for the extraction of rapidly-quenched filaments from a high melting
point and/or reactive melt.
[0010] According to the invention the apparatus for casting metal filaments directly from
the melt comprising a tiltable crucible which is constructed of thermally conductive
material for holding a metal charge, means for supplying heat to melt the metal charge
contained in said crucible to form a melt, a chill surface provided by a heat extracting
member for deposition of molten metal thereon for quenching into filament together
with means for advancing said chill surface, and means for tilting said crucible is
characterized in that the apparatus comprises a pouring spout forming an integral
part of said crucible, one or more cooling passages internal to said crucible for
passing a cooling medium therethrough to provide a solidified layer of the melt for
preventing interaction between the melt and said crucible and the means for tilting
said crucible elevate the melt into said spout for deposition onto the chill surface
as it is being advanced.
[0011] The invention provides an apparatus for casting metal filament directly from the
melt when the metal filament is made from high temperature and/or reactive materials.
A heating source such as an electric arc is employed for heating the metal and/or
holding it in molten condition. The metal charge is held in a cooled, tiltable crucible,
which is constructed of high thermal conductive material. When an arc source is employed,
an electrically conductive material is employed for crucible material. Suitable materials
of construction for the crucible include copper, graphite, brass, etc.
[0012] The crucible has one or more internal passages, and a cooling medium is passed through
these channels. When the apparatus includes an electrode, it is associated with the
crucible and an arc is struck between the electrode and the metal charge contained
in the crucible. The heat generated by the arc is used to melt the metal and/or hold
it in molten condition.
[0013] To effect rapid quenching of the molten metal and thereby form a continuous filament,
the apparatus further includes an advanceable chill surface for depositing the molten
metal thereon. The crucible has a pouring spout, and means are provided for tilting
the crucible to elevate the molten metal into the spout of the crucible for deposition
onto the chill surface as it is being advanced. The chill surface is provided with
a heat extracting member which may be constructed of any metal having relatively high
thermal 'conductivity, such as copper, beryllium-copper, molybdenum, iron, and the
like. The metal solidifies in contact with the chill surface and is drawn out by the
advancing chill surface into a continuous metal strip.
Fig. 1 is a schematic view of a cross-section of one embodiment of the present invention.
Fig. 2 is a schematic of the crucible and spout configuration of one embodiment of
the present invention wherein the spout contains an insulating insert.
Fig. 3 is a perspective view of another embodiment of the invention where a chamber
encloses the crucible and the heat extracting disk.
Fig. 1 is one embodiment of the present invention. The apparatus has a heat extracting
crucible 2 for containment of a molten melt 4. The crucible 2 is fabricated of a high
conductivity material such as copper, brass or graphite. The crucible 2 has a coolant
inlet 5, a channel 6 and a coolant outlet 7 for the passage of a coolant such as water
therethrough. The coolant enhances the heat extracting characteristics of the crucible
2. A spout 8 is positioned on the peripheral edge of the crucible 2.
[0014] The spout 8 can optionally be insulated with an insulating insert 10 as is illustrated
in Fig. 2. This insert can be made of a material such as zirconia, boron nitride,
alumina, or alternatively of a material such as clay graphite. The insert can be heated
by heating element 12. When the insert is graphite or clay graphite, it can be readily
coupled to a magnetic field, and the heating may be with an induction coil.
[0015] Again referring to Fig. 1, a metal charge may be melted to form the molten metal
4 which is maintained liquid in the crucible 2 by means for supplying heat to the
charge and/or the molten metal 4. The heating means illustrated is an arc source 14
which preferably has a water-cooled electrode holder 16 and a non-consumable electrode
18. Typically, tungsten is used as a non-consumable electrode 18. This electrode 18
is maintained at a potential with respect to the molten metal 4. Typically, the voltage
applied between the molten metal 4 and an electrode 18 will be between about 200 and
500 volts AC. A power supply 20 is connected between the electrode holder 16 and the
crucible 2. The power supply 20 may alternatively be connected to multiple electrodes
to provide a potential between the electrodes and the molten metal 4.
[0016] It should be appreciated that while the means for heating the molten metal 4 is illustrated
as an arc source 14, other means such as an e-beam or a laser could be employed. The
molten metal 4 is isolated from the crucible by a solidified layer 22. This solidified
layer 22 has the same composition as the molten metal 4. This solidified layer 22,
or crust, prevents reaction between the molten metal 4 and the crucible 2.
[0017] A heat extracting disk 24 having a circumferential peripheral edge 26 is connected
to a means for rotating the disk, such as a motor 27 shown by dashed lines. The disk
24 provides a heat extracting surface with a means for moving the heat extracting
surface. Other means such as a rotating belt could also be employed.
[0018] When the spout 8 of the crucible 2 is coplanar with the peripheral edge 26 of the
disk 24, the spout 8 can be brought into close proximity with the peripheral edge
26 by pivoting the crucible 2 on the pivotal mounts 28. The pivotal motion will bring
the molten metal 4 into the spout 8. As the molten metal 4 makes contact with the
peripheral edge 26, a filament 30 will be drawn. When the peripheral edge 26 is a
right cylindrical surface, the filament drawn will tend to be a flattened ribbon.
[0019] For the best control of the filament size, it is preferred that the spout 8 have
a channel with a radius of curvature of between about 0.15 cm. and 0.5 cm. The lower
limit insures that the channel will remain unconstricted during the casting of the
filament 30, while the upper limit is a practical limit beyond which it is difficult
to maintain a constant head during the formation of the filament -30.
[0020] In the event that a more cylindrical filament is sought, the peripheral edge 26'
can be made a tapered convex surface as is illustrated in Fig. 3 by the surface 26'.
In this case the spout 8 must be modified so as to have a contoured surface which
is a mirror image of the peripheral edge 26'. When the molten metal 4 readily reacts
in air, it is. preferred to provide a controlled atmosphere. Fig. 3 illustrates a
chamber 32 which is provided for enclosing the crucible 2 and the disk 24. The chamber
32 has an outlet 34 for evacuation which is closeable by a valve 36. There is an inlet
38 which again is provided with a valve 40. This inlet 38 serves to supply a protective
atmosphere for the crucible 2. The arc source 14 passes through a cover 42 of the
chamber 32. A rotatable seal 44 is provided between the electrode holder 16 and the
removable cover 42. A removable cover 42 allows access to the crucible 2 and the disk
24. In order to further illustrate the present invention the following examples are
given.
Examples 1-9
[0021] A series of samples were melted in a water-cooled copper crucible. The charge size
varied between 50 and 100 grams. A nonconsumable tungsten electrode was employed to
heat the melts. The melts were cast under an argon atmosphere. This was accomplished
by placing the crucible and the disk in a chamber which was evacuated to 10-
4 torr (1.33 to-
2Pa) and thereafter backfilled with high purity argon to about 20 cm of mercury. An
arc was struck between the charge which was in the form of a pellet, and the electrode.
By gradually tilting the crucible the molten metal was brought into the spout and
in kissing contact with the right cylindrical surface of the rotating chill disk.
The disk had a diameter of about 12 inches (30.5 cm) and was rotated at between about
1200 rpm and 1600 rpm. The disk was a water-cooled molybdenum wheel. A filamentary
fiber was extracted or dragged from the melt by the wheel. The materials cast are
summarized in the table.
1. Apparatus for casting metal filaments directly from the melt comprising a tiltable
crucible (2) which is constructed of thermally conductive material for holding a metal
charge, means (14) for supplying heat to melt the metal charge contained in said crucible
to form a melt, a chill surface (26) provided by a heat extracting member for deposition
of molten metal thereof for quenching into filament, together with means (27) for
advancing said chill surface, and means for tilting (28) said crucible, characterized
in that the apparatus comprises a pouring spout (8) forming an integral part of said
crucible (2), one or more cooling passages (6) internal to said crucible for passing
a cooling medium therethrough to provide a solidified layer of the melt for preventing
interaction between the melt (4) and said crucible and the means for tilting (28)
said crucible elevate the melt (4) into said spout (8) for deposition onto the chill
surface (26) as it is being advanced.
2. The apparatus of claim 1 wherein said spout (8) has a channel with a radius of
curvature between about 0.15 cm and 0.5 cm.
3. The apparatus of claim 1 wherein said thermally conductive crucible (2) is also
electrically conducting and said means (14) for supplying heat to the metal charge
is an electrode associated with said crucible for striking an arc between said electrode
and the metal charge contained in said crucible to melt the metal charge.
4. The apparatus of claim 3 wherein said spout (8) has an insulating insert (10) with
means (12) for heating said insert.
5. The apparatus of claim 2 wherein said means for supplying heat (14) to the metal
charge comprises at least two non-consumable electrodes; and a power supply connected
between said electrodes, said power supply passing a current between said electrodes
via said metal charge.
1. Appareil pour couler des filaments métalliques directement à partir du bain fondu
comprenant; un creuset basculable (2) qui est construit en un matériau thermiquement
conducteur pour contenir une charge de métal, des moyens (14) pour fournir de la chaleur
afin de fondre la charge de métal contenue dans ledit creuset, de façon à former un
bain fondu, une surface de refroidissement (26) formée par un organe d'extraction
de chaleur pour le dépôt sur elle du métal fondu pour la trempe sous forme d'un filament,
ainsi que des moyens (27) pour faire avancer ladite surface de refroidissement, et
des moyens (28) pour basculer ledit creuset, caractérisé en ce que l'appareil comprend
un goulot (8) de déversement formant une partie intégrale dudit creuset (2), un ou
plusieurs passages (6) de refroidissement à l'intérieur dudit creuset pour y faire
passer un milieu de refroidissement de façon à former une couche solidifiée du bain
fondu afin d'empêcher une interaction entre le bain fondu (4) et ledit creuset, et
lesdits moyens pour basculer ledit creuset élevant le bain fondu (4) jusque dans ledit
goulot (8) pour former un dépôt sur ladite surface (26) de refroidissement pendant
qu'elle avance.
2. L'appareil de la revendication 1 dans lequel ledit goulot (8) comporte un canal
avec un rayon de courbure compris entre 0,15 et 0,5 cm environ.
3. L'appareil de la revendication 1, dans lequel ledit creuset thermiquement conducteur
(2) est également électriquement conducteur, et lesdits moyens (14) pour fournir de
la chaleur à ladite charge de métal sont constitués par une électrode associée audit
creuset pour former un arc entre ladite électrode et la charge de métal contenue dans
ledit creuset de façon à faire fondre la charge de métal.
4. L'appareil de la revendication 3, dans lequel ledit goulot (8) comporte une pièce
rapportée isolante (10) avec des moyens (12) pour la chauffer.
5. L'appareil selon la revendication 2, dans lequel lesdits moyens pour fournir de
la chaleur (14) à la charge de métal comprennent au moins deux électrodes non consommables;
et une source de puissance reliée entre lesdites électrodes, ladite source de puissance
faisant passer un courant entre lesdites électrodes à travers ladite charge de métal.
1. Vorrichtung zum Gießen von Metalldrähten direkt aus der Schmelze mit einem kippbaren
Schmelzbehälter (2), der aus wärmeleitfähigem Material konstruiert ist, zur Aufnahme
einer Metallcharge, Einrichtungen (14) zur Zuführung von Wärme zum Schmelzen der in
dem Schemlzbehälter enthaltenen Metallcharge unter Bildung einer Schmelze, einer Abkühloberfläche
(26), die von einem wärmeextrahierenden Teil gebildet wird, zur Ablagerung von geschmolzenem
Metall darauf, um dieses zu einem Draht abzukühlen, zusammen mit Einrichtungen (27)
zum Vorrücken dieser Abkühloberfläche und Einrichtungen zum Kippen (28) des Schmelzbehälters,
dadurch gekennzeichnet, daß die Vorrichtung eine aus einem Stück mit dem Schmelzbehälter
(2) bestehende Ausgußtülle (8) und einen oder mehrere Kühlkanäle (6) im Inneren des
Schmelzbehälters zum Durchleiten eines Kühlmediums besitzt, um eine verfestigte Schicht
der Schmelze zu bekommen und so eine Wechselwirkung zwischen der Schmelze (4) und
dem Schmelzbehälter zu verhindern, und daß die Einrichtungen zum Kippen .(28) des
Schemlzbehälters die Schmelze (4) in die Tülle (8) zur Ablagerung auf der Abkühloberfläche
(26), während diese vorangerückt wird, heben.
2. Vorrichtung nach Anspruch 1, worin die Tülle (8) einen Kanal mit einem Krümmungsradius
zwischen etwa 0,15 cm und 0,5 cm besitzt.
3. Vorrichtung nach Anspruch 1, worin der wärmeleitfähige Schmelzbehälter (2) auch
elektrisch leitend ist und die Einrichtung (14) zur Zuführung von Wärme zu der Metallcharge
eine mit dem Schmelzbehälter verbundene Elektrode ist, die einen Lichtbogen zwischen
der Elektrode und der in dem Schemlzbehälter enthaltenen Metallcharge erzeugt, um
die Metallcharge zu schmelzen.
4. Vorrichtung nach Anspruch 3, worin die Tülle (8) einen isolierenden Einsatz (10)
mit Einrichtungen (12) zum Erhitzen dieses Einsatzes besitzt.
5. Vorrichtung nach Anspruch 2, worin die Einrichtung zur Zufuhr von Wärme (14) zu
der Metallcharge wenigstens zwei nicht verbrauchbare Elektroden und eine mit diesen
Elektroden verbundene Stromzufuhr besitzt, wobei die Stromzufuhr einen elektrischen
Strom zwischen diesen Elektroden über die Metallcharge leitet.