AU2021100090A4

AU2021100090A4 - ICS- Counter Gravity Casting: Intelligent Centrifugal Counter Gravity Low- cost Casting System

Info

Publication number: AU2021100090A4
Application number: AU2021100090A
Authority: AU
Inventors: M. Ashok Kumar; S. B. Chordiya; Kiran Chunilal More; Pawan Kumar Singh; Pari Nidhi Singh; Vrushsen Purushottam Pawar; Beg Raj; Prasada Rao Bayarapu; S. Saravanan; B. Venkatesh
Original assignee: Purushottam Pawar Vrushsen Dr
Current assignee: Purushottam Pawar Vrushsen Dr
Priority date: 2021-01-07
Filing date: 2021-01-07
Publication date: 2021-04-15
Anticipated expiration: 2029-01-07

Abstract

Our Invention "ICS- Counter Gravity Casting" is a counter gravity casting apparatus includes a reusable metal mold having a plurality of mold cavities, a feed tube configured to feed molten alloy into the mold, and a vacuum fitting configured to permit a vacuum to be applied to the mold. The invented technology also includes a multiple metal sections configured such that adjacent metal sections mate to one another, the metal sections being separable from one another and the metal sections include recesses that form the mold cavities, and the mold includes a sprue and multiple runner passages. The invented technology is also sprue is configured to receive molten alloy from the feed tube and the multiple runner passages are configured to feed molten alloy from the sprue to the mold cavities and the methods of casting bulk amorphous alloy articles or feedstock is described. The invented technology also includes the vacuum, counter gravity casting of molten metal includes a bottom drag member and a casting mold member thereon engaged together at a parting plane. The invented technology also a valve member is disposed adjacent the parting plane in an in gate to a mold cavity formed at least in part in the casting mold member and is movable between a valve seat on the bottom drag member and a stop surface on the casting mold member to permit filling of the mold cavity in counter gravity manner from an underlying molten metal pool when the bottom drag member is immersed therein and to prevent backflow of the molten metal from the mold cavity when the bottom drag member is withdrawn from the pool after mold filling and before solidification of the molten metal in the mold cavity. 21 to vacuum j_00 to vacuum T 152 154 108 vacuurn tube 106 cnnecor - 1 14 b 102 mold height adjust 1062 14neto 120 126 12614 120O 122 156 122- 144 136 124 104 feed tube 313 1132 134 molaten alloy 0gas 158 e1 feed 130 crucible height146 144D vacuum chamber FIG. 1 ILLUSTRATES AN EXEMPLARY COUNTER GRAVITY CASTING APPARATUS ACCORDING TO AN EXEMPLARY EMBODIMENT.

Description

to vacuum j_00 to vacuum T 152 154

108 vacuurn tube b 14 - 1 106 cnnecor 102 mold height adjust 1062 14neto 120 126 12614 120O

122 156 122- 144

136 124 104 feed tube 313

1132

134 molaten alloy 0gas 158 e1 feed

130 crucible height146

144D vacuum chamber

FIG. 1 ILLUSTRATES AN EXEMPLARY COUNTER GRAVITY CASTING APPARATUS ACCORDING TO AN EXEMPLARY EMBODIMENT.

ICS- Counter Gravity Casting: Intelligent Centrifugal Counter Gravity Low- cost Casting System

FIELD OF THE INVENTION

Our Invention "ICS- Counter Gravity Casting" is an intelligent centrifugal counter gravity low- cost casting system and also relates to counter gravity casting of metallic alloys, and more particularly to counter gravity casting of bulk amorphous metal alloys and feedstock for bulk amorphous alloys.

BACKGROUND OF THE INVENTION

Counter gravity casting methods are known in the art for making investment castings using ceramic shell molds, such as described, for example, in U.S. Pat. Nos. 3,863,706, 3,900,064, 4,589,466, and 4,791,977. Such ceramic molds are formed by a process known as the lost wax process. The ceramic shell mold is disposed in a vacuum container, and a fill tube, which communicates with a riser passage that extends from the bottom of the ceramic shell mold, extends out of the container for immersion in a pool of molten metal. Application of a relative vacuum causes the fill tube to draw molten metal upwardly into the riser and mold cavities of the ceramic shell mold.

Methods are also known in the art for preparing and casting bulk amorphous alloys (also called bulk metallic glasses or BMG) of various compositions, such as, for example, U.S. Pat. Nos. 5,797,443, 5,711,363, 7,293,599, and 6,021,840.

The present inventors have observed a need for improved approaches for casting bulk amorphous alloys (or feedstock for such alloys) directly from the melt that permit the casting of large numbers of cast articles in a cost effective and efficient manner. Exemplary approaches and systems described herein may address such needs.

A backpressure casting method in gas-permeable ceramic shell molds is described in US Pat. foundry cavities, the shape of which follows the shape of the molded products. Foundry cavities are located along the entire height of the central sprue channel (from its lower point to the upper), and each casting cavity is connected to the central sprue channel by a narrow lateral sprue channel, the geometry of which depends on the shape of the casting cavity.

The ceramic mold is placed in an evacuated container and the lower end of its central gate channel is connected to a feed pipe, the lower end of the container outward of which is immersed in a molten metal bath located below. After the pipe is lowered into the bath with molten metal, a vacuum is created in the container (vacuum), under the influence of which the molten metal rises into the central gate channel of the mold and fills the casting cavities through the side gate channels. Typically, the vacuum in the container is maintained until the final solidification of the metal in the side gating channels and in the mold casting cavities, although US Pat. after receiving the finished castings, pour the molten metal back into the bath located under the container and then use it to make other castings.

A ceramic shell mold is placed in a support medium consisting of separate particles, in particular in a molding mixture, which, as described in US Pat. No. 5,069,271, is filled in a vacuum container. The use of such a support medium makes it possible to reduce the thickness of the shell mold. The vacuum in the container is created using a vacuum head, which is used not only to evacuate the container, but also to compress the support medium around the shell mold.

During backpressure casting, the filling with molten metal of the same casting cavities located at different heights along the length of the central vertical sprue channel occurs over various periods of time. Depending on the location of the casting cavity along the height of the central sprue channel, the gas permeability of the support medium and the ceramic shell mold, the vacuum rate and the final value of the vacuum created in the container, as well as a number of other factors for filling molten metal of different casting cavities of the same shell form Different time periods are required, which can differ from each other by at least two times. So, in particular, the lower cavity of the mold is filled with molten metal more slowly than the upper cavity.

Due to the relatively slow filling, the lower mold cavities are not completely filled with molten metal. On the other hand, if the upper cavities are filled too quickly with molten metal, gas remains in them, which forms various kinds of defects in finished products cast in these cavities. Unfortunately, all attempts to solve one of these problems (associated with slow or too fast filling of various mold cavities with molten metal) automatically lead to an exacerbation of another problem.

A feature of backpressure casting is also the large pressure difference in the various mold cavities. When creating a vacuum in the container, the pressure in each cavity of the mold is equal to the difference between the external (atmospheric) pressure that acts on the surface of the molten metal bath and the column pressure of molten metal in the central gate channel of the mold, which acts against atmospheric pressure on the bath surface. Therefore, the pressure in the mold casting cavities depends on their location along the height of the central gate channel and, in particular, on the height difference between the surface of the bath and the side gate channel through which molten metal enters the cavity.

Obviously, as the height of the shell mold increases, the difference in pressure in the mold cavities located at different heights of the central gate channel increases. The decrease in pressure increases the shrinkage of the metal and leads to the appearance of various defects associated with the formation of gas inclusions in the molded products in the upper cavities of the mold.

When molten metal rising under the influence of rarefaction reaches the closed upper end of the central gate channel, the upper mold cavities do not yet have time to completely fill with metal. When the molten metal reaches the upper end of the central gate channel, a sharp pressure drop occurs in the side gate channels of the upper mold cavity, and the upper mold cavities fill up with metal too quickly. The gas contained in the molten metal flows through the sprues into the upper mold cavities and forms gas inclusions in the products cast in them.

In order to avoid the reverse flow of molten metal from the side gate channels and mold cavities, the pipe through which the molten metal enters the mold from the bath is kept immersed in the bath long enough for the metal to solidify completely in the mold cavities and side gate channels. The need for prolonged immersion of the pipe in a bath with molten metal increases the duration of casting and requires lowering the mold as the level of molten metal in the bath decreases, resulting in an increase in the degree of influence on the shape of the induction field that is used to heat the bath.

The induction field can reduce the rate of solidification of the metal in the mold or even cause it to heat up, as well as cause damage to the container portion adjacent to the pipe and air to enter the lower mold cavities. The design of the gating system is always associated with a compromise, since the side gating channels, on the one hand, must have a sufficiently large volume necessary to fill the mold casting cavities with molten metal, and on the other hand, must be narrow enough to allow the metal to solidify in the cavities forms occurred in the appropriate time mode. Such restrictions on the design of the gating system limit both the size and weight of the molded product, which, when manufactured by the method described in US Pat. No. 3,863,706, usually does not exceed one pound.

For casting large products by backpressure, the method described above must be improved accordingly using a special device that holds molten metal in the central gate channel. In the patent US 4,589,466 for this purpose it is proposed to use a valve that is installed on the pipe connecting the mold to the bathtub with molten metal and is closed after filling the mold with metal. For the same purpose, one can also use a shut-off valve with a ceramic-coated ball mounted in a pipe connecting the mold with a bath with molten metal. The use of such a valve for backpressure molding is proposed, in particular, in US Pat. No. 3,774,668.

US Pat. No. 4,961,455 describes a "check valve" with a ceramic-coated ferromagnetic ball which, under the influence of a field of magnets, seals the pipe connecting the central gate channel to the molten metal bath. To solve this problem, it was also proposed to use a siphon-type shutter installed in a pipe connecting the bath with molten metal to the central gate channel, and the mold will roll over after casting. To eliminate the backflow of molten metal from the central gate channel when the mold overturns, you can also use the ceramic filter proposed in US Pat. No. 4,982,777, the filter in combination with a spiral channel proposed in US Pat. No. 5,146,973, or the siphon type channel proposed in US Pat. No. 5,904,762, made in a pipe connecting the central sprue channel with a bath with molten metal.

All these solutions to one degree or another limit the amount of molten metal flowing through the central gate channel of the mold and increase the duration of its filling. At the same time, the efficiency of using molten metal, which after solidification remains in the central gate channel, decreases. The solutions proposed in the above patents require the presence of a sufficiently large free space around the central gate channel to cut the castings from the central profit, and therefore significantly limit the number of casting cavities that can be placed in the mold around its central gate channel.

In US Pat. No. 4,112,997, it was proposed to use "stabilizing" nets located in the side gating channels of the mold. Such grids, according to the authors of the invention described in the said patent, after increasing the pressure in the mold to atmospheric, should hold the molten metal in the mold cavity. The casting method proposed in this patent, which has undoubted practical feasibility and is economically viable, removes the aforementioned restriction on the geometry of the casting associated with the need to cut individual castings from the central profit of the casting, since it essentially eliminates the presence of the shape of the central gating channel in the gating system.

The present invention was based on the task of developing a method and apparatus for backpressure centrifugal casting, which would solve the above problems and eliminate the contradictions associated with filling casting chambers located at different heights along the length of the central gate channel.

Another objective of the present intention was to develop a method and apparatus for backpressure casting, in which the molten metal or alloy is held in the casting cavities and side gating channels under the action of centrifugal forces and in which, after the molten metal is drained from the central gating channel, finished castings are obtained that are not connected to the central profit by metal hardened in the side gating channels.

This invention relates to apparatus and methods of counter gravity casting of molten metal. More particularly, the invention concerns such casting in which the molten metal is caused to flow into and fill the cavities of gas-pervious molds by low pressure induced in a vacuum chamber sealed around them.

Prior art apparatus and methods of the type concerned set forth in U.S. Pat. Nos. 3,900,064 and 4,589,466 have been successful in producing high quality castings, superior in many respects to castings produced by pouring methods dependant on gravity-induced flow. The vacuum chamber is usually maintained at a pressure at least as low as about 1/3 (5 p.s.i.) below atmospheric pressure while the molten metal is essentially at atmospheric pressure and, to fill thin molding cavities, often as low as 13 p.s.i. below atmospheric pressure.

Also, after the mold is filled, the metallostatic pressure in the lower part of the mold is additive to the vacuum pressure, so the total metal pressure in that volume often reaches 18 psi. These metal pressures generate stresses in the mold walls depending on the shape of the mold cavity and its size. The size of these stresses increases as the parts overall dimensions' increase. For example, a part 2"x4"x1/4" could have a force of 144 lbs. to contain while a part 6"x4"x1/4" would have a force of 432 lbs. to contain. Such high forces when combined with the high temperatures of steels especially, can cause mold wall movement, metal penetration into the mold face, and even outright mold failure especially if there are any structural defects in the molds.

The practical effect is that costly measures may be required to avoid these problems and certain larger shapes cannot be made by the methods taught. Also, the methods require molds of high strength and inside faces of low porosity, such as high temperature bonded ceramic shell molds. Lower strength molds, such as low temperature bonded sand molds, have been filled primarily by other methods, such as the partial immersion of the mold in the molten metal with vacuum applied only to the upper part of the mold, in accordance with U.S. Pat. Nos. 4,340,108 and 4,532,976.

PRIOR ART SEARCH

US3863706A1972-12-041975-02-04Hitchiner Manufacturing Co Metal casting US3900064A1972-12-041975-08-19Hitchiner Manufacturing Co Metal casting US4589466A1984-02-271986-05-2OHitchiner Manufacturing Co., Inc. Metal casting US4791977A1987-05-071988-12-2OMetal Casting Technology, Inc.Counter gravity metal casting apparatus and process US5044420A*1990-08-131991-09-03General Motors Corporation Vacuum-assisted, counter gravity casting apparatus and method US5161604A*1992-03-261992-11-10General Motors Corporation Differential pressure, counter gravity casting with alloy ant reaction chamber US5288344A1993-04-071994-02-22California Institute Of Technology Beryllium bearing amorphous metallic alloys formed by low cooling rates US5431212A*1993-07-201995-07-11Toyota Jidosha Kabushiki Kaisha Method of and apparatus for vacuum casting US5711363A1996-02-161998-01-27Amorphous Technologies International Die casting of bulk-solidifying amorphous alloys US5758712A1994-05-191998-06-02Georg Fischer Disa A/S Casting device for non gravity casting of a mould with a light-metal alloy through a bottom inlet in the mould US4340108A *1979-09-121982-07-20Hitchiner Manufacturing Co., Inc. Method of casting metal in sand mold using reduced pressure US4606396A*1978-10-021986-08-19Hitchiner Manufacturing Co., Inc. Sand mold and apparatus for reduced pressure casting

OBJECTIVES OF THE INVENTION

1. The objective of the invention is to a counter gravity casting apparatus includes a reusable metal mold having a plurality of mold cavities, a feed tube configured to feed molten alloy into the mold, and a vacuum fitting configured to permit a vacuum to be applied to the mold. 2. The other objective of the invention is to a multiple metal sections configured such that adjacent metal sections mate to one another, the metal sections being separable from one another and the metal sections include recesses that form the mold cavities, and the mold includes a sprue and multiple runner passages. 3. The other objective of the invention is to a configured to receive molten alloy from the feed tube and the multiple runner passages are configured to feed molten alloy from the sprue to the mold cavities and the methods of casting bulk amorphous alloy articles or feedstock is described. 4. The other objective of the invention is to a vacuum, counter gravity casting of molten metal includes a bottom drag member and a casting mold member thereon engaged together at a parting plane. 5. The other objective of the invention is to a valve member is disposed adjacent the parting plane in an in gate to a mold cavity formed at least in part in the casting mold member and is movable between a valve seat on the bottom drag member and a stop surface on the casting mold member to permit filling of the mold cavity in counter gravity manner from an underlying molten metal pool when the bottom drag member is immersed therein and to prevent backflow of the molten metal from the mold cavity when the bottom drag member is withdrawn from the pool after mold filling and before solidification of the molten metal in the mold cavity.

SUMMARY OF THE INVENTION

According to one example, a counter gravity casting apparatus, comprises a reusable metal mold comprising a plurality of mold cavities; a feed tube configured to feed molten alloy into the mold; and a vacuum fitting connected to the mold and configured to permit a sub-ambient pressure to be applied to an interior of the mold. The mold comprises multiple metal sections configured such that adjacent metal sections mate to one another, the metal sections being separable from one another, wherein the metal sections comprise recesses that form the mold cavities.

The mold includes a sprue and multiple runner passages, wherein the sprue is configured to receive molten alloy from the feed tube, and wherein the multiple runner passages are configured to feed molten alloy from the sprue to the mold cavities.

According to another example, a method for counter gravity casting, comprises applying a sub-ambient pressure to an interior of a reusable metal mold comprising a plurality of mold cavities and feeding a molten alloy upward through a feed tube from a crucible and into the reusable metal mold and into the plurality of mold cavities under a pressure differential generated at least partially by the sub-ambient pressure at the interior of the mold, the mold being disposed above the crucible. The mold comprises multiple metal sections that are configured such that adjacent metal sections mate to one another, wherein the metal sections are separable from one another, and wherein the metal sections comprise recesses that form the mold cavities.

The mold includes a sprue and multiple runner passages, wherein the sprue is configured to receive molten alloy from the feed tube, and wherein the multiple runner passages are configured to feed molten alloy from the sprue to the mold cavities. The method also comprises cooling the molten alloy in the mold cavities of the mold at a rate sufficient to solidify the molten alloy in the mold cavities while at least some of the molten alloy disposed within the sprue remains in a molten state. The method further comprises releasing the pressure differential to permit the molten alloy disposed within the sprue to return to the crucible, and removing the cast articles.

According to another example, an article of manufacture comprises a refractory article; a bulk metallic glass structure disposed in contact with the refractory article; and a hermetic or vacuum tight seal at an interface between the bulk metallic glass structure and the refractory article formed by a reaction of molten alloy that forms the bulk metallic glass structure with the refractory article during a casting process.

The invention provides a method and apparatus for casting a plurality of products by a back pressure method in a ceramic casting mold that has a vertical central sprue channel and a plurality of casting cavities located at different heights along the length of the central sprue channel and connected to it by the side sprue channels through which molten metal rising from the bath enters the casting cavities of the mold, in which centro the flowing forces acting in the direction of the casting cavities on the molten metal that remains in the side gating channels, and in which the molten metal merges from the central gating channel until it finally hardens in the casting cavities of the mold and in the side gating channels, which at least remain at least partially filled with molten metal that enters the casting cavities during shrinkage of a container with a molten metal shape hardening in them during rotation. During rotation of the container, the molten metal in the cavities of the mold solidifies and turns into many individual castings (products).

After the solidification of the molten metal, the rotation of the container with the mold stops. Proposed in the invention method allows to increase the useful yield of metal or alloy up to about 80%. In addition, the proposed invention, the method allows to increase the number and size of molded products having, by reducing shrinkage, increased density.

After the molten metal is drained from the central sprue channel and the pressure in it increases to atmospheric, the molten metal remaining in the side sprue channels and in the mold cavities under the influence of external (atmospheric) pressure and the pressure from the centrifugal forces resulting from the rotation of the container is compacted, and the density castings by reducing shrinkage rises. When the molten metal is drained from the central gate channel, the metal remaining in the side gate channels hardens faster, and the reverse flow of molten metal from the side gate channels is almost completely eliminated.

In a preferred embodiment of the invention, when casting molten metal products prone to shrinkage, the filling of the central vertical sprue channel with the rising molten metal occurs during mold rotation while the mold is filled with mold cavities. On the other hand, the mold can also be rotated after the central gate channel is filled with molten metal. The form can rotate around its longitudinal axis or around another axis parallel to the longitudinal axis of the form and offset from it by a certain distance.

In another embodiment of the invention, it is proposed to use a mold with casting cavities that are elongated in the direction of the central vertical sprue channel and are positioned relative to it at a certain angle so that the theoretical free surface of the molten metal formed when the metal is drained from the central sprue channel during rotation of the mold, passes only through the side gate channels and does not pass through the mold casting cavities, which as a result remain filled and molten metal during its discharge from the central gate channel.

In yet another embodiment of the invention, it is proposed to use a mold with casting cavities that are elongated in the direction of the central vertical gate channel and are connected to it by side gate channels located at different heights along the length of the central gate channel. The molten metal first hardens in the areas of the casting cavity located between the side gating channels, and in several more or less separate places of the casting cavity between the areas with hardened metal there remains a certain amount of molten metal, which from the side gating channels partially filled with metal falls into the corresponding place in the casting cavities, compensating during the rotation of the container, the shrinkage of the metal hardening in the cavity.

The present invention relates to the casting of metal or alloy products in both gas permeable and gas impermeable molds. The casting of various metal or alloy products by the method of the invention into gas-tight foundry molds makes it possible, moreover, to reduce or completely eliminate the formation of gas inclusions in products molded in such molds.

In a backpressure molding device according to the invention, the mold is immersed in a carrier (or support) medium consisting of individual particles, in particular in a molding mixture with which the mold container is filled. The container in which the vacuum is created, under the action of which the molten metal rises and fills the central sprue channel, is driven into rotation by a drive mechanism located on the supporting frame of the container itself.

The present invention also provides another embodiment in which instead of a ceramic mold made by investment casting, a casting mold placed in a container is used for casting products, which melts and evaporates during casting when exposed to molten metal. Such a model destroyed during casting, placed in a material consisting of individual particles, with which the container is filled, consists of a section forming a central vertical sprue channel and a plurality of sections forming casting cavities located at different heights along the length of the section forming a central sprue channel.

Each section forming a casting cavity is connected to a section forming a central sprue channel, a section forming a corresponding lateral sprue channel. The molten metal gradually destroys the model, and after it solidifies in a material consisting of separate particles, with which the container is filled, a casting is formed, consisting of central profit and products cast in the cavities, connected to it by metal remaining in the side gate channels.

The method proposed in the invention ensures uniform filling of all casting cavities located at different heights at a uniform height and a uniform pressure distribution in different casting cavities, and also reduces a sharp change in pressure in the upper casting cavities and limits the formation of gas inclusions in the cast products.

It has been discovered that aforesaid difficulties are avoided or minimized, and other advantages ensue, by providing, in the gas-pervious mold, a fill passage which communicates with other cavities of the mold and by maintaining the upper part of this passage at a lower pressure than the pressure in the vacuum chamber surrounding the mold.

The apparatus of the invention includes, as in the prior art, a gas-permeable mold having cavity means therein, including a fill passage communicating laterally with other cavity means of the mold, the fill passage having a lower open end and an upper end above its uppermost lateral communication with other cavity means; a sealable mold support chamber for the mold; means for communicating the lower open end of the fill passage of a mold sealed in the chamber with a body of molten metal to be cast; and pressure reducing means for producing in the sealed chamber pressure sufficiently lower than the pressure on the molten metal to cause the molten metal to flow through the communicating means and fill passage to fill the other cavity means of the mold. However, according to the invention, the pressure reducing means includes differential pressure reducing means for selectively maintaining, during filling of the mold, the upper part of the fill passage at a lower reduced pressure than the reduced pressure in the support chamber external to the mold.

In the method according to the invention the differential pressure reducing means is used to provide, in the upper end of the fill passage, a first pressure sufficiently lower than the pressure on the supply of molten metal to cause the molten metal to fill the passage and maintain it full; and simultaneously to provide in the chamber externally of the mold a second pressure, higher than the first pressure, and sufficiently lower than the pressure on the supply of molten metal to insure fill out of the other cavity means by molten metal flowing thereto from the fill passage. Preferably, the second pressure is raised after fill out of the cavity means, while the first pressure is maintained in the upper end of the fill passage and molten metal remains flowable in the fill passage and other cavity means.

In preferred apparatus, the differential pressure reducing means has a conduit with an open end in the chamber, the mold has a gas permeable closure for the upper end of the fill passage and means are provided for sealing the open end of the conduit to the mold about the fill passage upper end; the closure is a plug inserted in the top of the fill passage; and the top of the fill passage is above the other cavity means of the mold and/or the open end of the conduit is sealed about a larger area of the upper part of the mold including the top of the fill passage, to assist the filling of upwardly extending parts of other mold cavities beneath it.

The dual, independent control of low pressure inside and outside the mold provided by the invention enables fill out of casting cavities at lower total metal pressures against the inside of the casting cavities, reducing the potential for mold breakage and mold wall penetration by the metal and resulting in castings of superior finish and dimensional control. When used with low temperature bonded sand molds, it permits taller molds with more casting cavities, which may be formed of stacked sections bolted together, with substantial savings in cost of mold production as compared with prior apparatus and methods. Molds of large horizontal cross-section can be used with smaller diameter metal melts than before.

BRIEF DESCRIPTION OF THE DIAGRAM

FIG. 2 illustrates a perspective view of a portion of the exemplary counter gravity apparatus shown in FIG. 1.

FIG. 3A illustrates a perspective view of a portion of an exemplary reusable metal mold configuration according to an exemplary embodiment.

FIG. 3B illustrates a perspective view of a portion of another exemplary reusable metal mold configuration according to another exemplary embodiment.

FIG. 4A illustrates a cross-sectional side view of a portion of an exemplary reusable metal mold configuration according to an exemplary embodiment.

FIG. 4B illustrates a cross-sectional side view of a portion of another exemplary reusable metal mold configuration according to another exemplary embodiment.

FIG. 5A illustrates a cross-sectional side view of a portion of an exemplary reusable metal mold configuration and an exemplary ceramic insert according to an exemplary embodiment.

FIG. 5B illustrates a cross-sectional side view of the mold of FIG. 5A with the exemplary ceramic insert in place in the mold.

FIG. 5C illustrates an exemplary ceramic composite article with a bulk metallic glass portion resulting from a casting process using the mold and ceramic insert of FIG. 5B.

FIG. 6 illustrates a flow diagram for an exemplary method of counter gravity casting according to an exemplary embodiment.

DESCRIPTION OF THE INVENTION

FIG. 1: illustrates an exemplary counter gravity casting apparatus 100 according to an exemplary embodiment. In this example, the apparatus 100 comprises a reusable metal mold 102, a crucible 130 for melting an alloy and for holding the molten alloy 134, a vacuum chamber 140 in which the mold 102, the crucible 130 and other components are disposed, and a feed tube 104 configured to feed molten alloy 134 into the mold 102. A vacuum fitting or connector 106 is connected to the top of the mold 102 and is configured to permit a sub-ambient pressure to be applied to an interior of the mold 102 via a vacuum tube, which can be connected to a suitable vacuum system including one or more vacuum pumps, pressure gauges, gas flow controllers and sources of gas (e.g., inert gas) so as to maintain a controllable pressure at the interior of the mold 102 in the range of atmospheric pressure (760 Torr) to sub-ambient pressures less than atmospheric pressure (e.g., a few hundred Torr to 10-6Torr), including low vacuums (e.g., 10-2 -6 Torr, for instance).

A vacuum valve 142 connected to a port of the vacuum chamber 140 is connected to a vacuum system (e.g., the same vacuum system or a different vacuum system) to evacuate the chamber 140 and maintain a desired level of pressure/vacuum in the chamber 140. A valve 144 is connected to a port on the vacuum chamber 140 to permit gas, e.g., inert gas such as argon, nitrogen, etc., to be fed into the chamber 140 to maintain a desired gaseous environment in the chamber 140 at a desired pressure. One or more pressure sensors 152 may be provided for measuring the pressure in the vacuum chamber 140, and one or more pressure sensors 154 may be provided for measuring the pressure in the vacuum arrangement (vacuum tube 108 and associated suitable connectors and valves) that communicates with the interior of the mold 102. Any suitable combination of gas flow controllers, pressure sensors, vacuum pumps and associated vacuum plumbing may be utilized to control the vacuum/pressure conditions and gaseous environment of the vacuum chamber 140.

One or more temperature sensors 156 (e.g., thermocouples) for measuring the temperature of one or more locations of the mold 102, and one or more temperature sensors 158 for measuring the temperature of one or more locations of the crucible 130, e.g., to monitor the temperature of the molten alloy 134. The crucible 130 may be heated by an induction heating coil 132, or by any other suitable means of heating, to both melt alloy constituents at the outset to make the alloy 134 and/or to heat the molten alloy 134 to maintain it a desired temperature.

The apparatus 100 also comprises a drive system, e.g., 146 and or 148, for controllably changing a vertical distance between the mold 102 and the crucible 130. Either, or both, of these exemplary drive systems permits the feed tube 104 to be immersed in the molten alloy 134, either by lowering the mold 102 toward the crucible 130, or by raising the crucible 130 toward the mold 102. The crucible may also comprise a cover 136 that has a movable lid 138 for exposing and covering a portion of the crucible 130. The lid 138 can be opened (using any suitable mechanical control system) when the feed tube 104 approaches the crucible 130, and the lid 138 can be closed after the feed tube 104 is removed from the crucible 130.

Covering the molten alloy 134 with the movable lid 138 can be useful for avoiding potential contamination of the molten alloy 134 both before the feed tube 104 is immersed in the molten alloy 134 for a casting event and after the feed tube 104 is removed from the molten alloy 134 following a casting event (so as to avoid contamination in preparation for a next casting event). In particular, this can prevent portions of the feed tube 104 from contaminating the molten alloy 134 should the feed tube crack after removal from the crucible. While FIG. 1 illustrates the mold 102 and the crucible 130 in one (i.e., the same) chamber 140, the mold 102 and the crucible 130 could be situated in separate vacuum chambers that communicate with one another via a gate value.

For instance, the crucible 130 could be situated in one vacuum chamber at one pressure, e.g., 5 psi, and the mold 102 could be situated in a separate vacuum chamber and could be brought to the same pressure, e.g., 5 psi. Each such vacuum chamber can have its own suitable vacuum plumbing, values, pressure sensors and vacuum pumps, etc. The vacuum chamber containing the mold 102 and the separate vacuum chamber containing the crucible 130 need not be brought to the same pressure level at the same time, but they should be brought to the same pressure level just prior to the opening of the gate valve that separates the two separate chambers for a casting event.

In the example of FIG. 1, the reusable metal mold 102 comprises a plurality of mold cavities 120 connected to a sprue 124 (e.g., a central sprue) via multiple runner passages 126. The mold 102 comprises multiple sections 122 (e.g., metal plates) configured such that adjacent sections 122 mate to one another so as to form the mold cavities 120, wherein the sections 122 are separable from one another. As shown in this example, the multiple metal sections 122 of the mold 102 may comprise metal plates oriented substantially horizontally.

A sectional perspective view of the mold 102 is illustrated in FIG. 2, and a perspective view of a bottom portion (several sections 122) of the mold 102 is shown in FIG. 3A. As shown in FIG. 3A, a given section 122 comprises cavity recesses 120 r, each of which forms a portion of a mold cavity 120, e.g., one-half of a mold cavity 120 in this example. The sections 122 in this example possess such recesses 120 rat opposing sides of the section 122. Likewise, a given section 122 comprises runner recesses 126 r, each of which forms a portion of a runner passage 126, e.g., one-half of a runner passage 126 in this example. When the sections 122 of the metal mold 120 are positioned together side-by side, these recesses 120 rand 126 r form the mold cavities 120 and runner passages 126, respectively. As shown in FIGS. 1 and 2, the sprue 124 is configured to receive molten alloy 134 from the feed tube 104, and the multiple runner passages 126 are configured to feed molten alloy 134 from the sprue 124 to the mold cavities 120. In some examples, multiple runner passages 126 may feed a single mold cavity 120 from any side of the mold cavity 120.

The mold 120 can be machined out of various metals, such as, for example, Cu, Cu Be, various tool steels such as H13, P20, etc., INCONEL@, stainless steel, and the like. The metal from which to fabricate the mold may also be an alloy formed of at least some the same constituents as the alloy being cast so as to reduce the potential for contamination of the cast alloy from erosion of the mold. Inner surfaces of the mold 102 including the mold cavities 120 and the runner passages 126 may be coated, if desired, with zirconia, yttria, or other suitable coatings to protect and enhance the longevity of those surfaces. The feed tube 104 may be formed from quartz, zirconia, or other suitable refractory materials, and may range in diameter from about 10 min to about 50 mm, though other diameters are possible as well. The feed tube 104 may be connected to the bottom of the mold 102 using any suitable tube connector, e.g., compression fitting, or may be fixed in place by providing a lip to the upper portion of the feed tube 104 that is then supported with a screw nut containing a hold for the feed tube 104.

Also shown in the example of FIG. 3A are alignment pins 160 extending from a surface of the section 122, which mate to corresponding alignment holes in an adjacent metal. Of course, this method of alignment is exemplary and any suitable approach for maintaining proper alignment between sections 122 may be used. The mold 102 may be held together by any suitable clamping or fastening mechanisms, e.g., clips, clamps, etc., so that the sections 122 of the mold 102 are held in intimate contact for the casting process. Metal or polymer gaskets may also be placed between adjacent sections 122 of the mold 102 to promote vacuum tight interfaces between the sections 122 as long as such gaskets do not interfere with the arrangement and tightness of the mold cavities 102.

In addition, separation springs may be placed between adjacent sections 122 of the mold 102 so that when the casting process is completed and the mold fasteners (e.g., clips, claims, etc.) are released, the sections 122 of the mold will be forced apart by the springs to facilitate removal of the cast articles from the mold cavities 120. In another example, the sections 122 may be configured such that the sprue opening 124 of each section tapers slightly such that the overall sprue 124 is tapered to be of relatively smaller diameter closer to the top of the mold 102 and of relatively larger diameter closer to the bottom of the mold 102. This tapered sprue shape may further facilitate separation of the mold sections 122.

In the example of FIG. 3A, adjacent mold cavities 120 in adjacent sections 122 that are vertically aligned with one another, as shown by adjacent dotted circles positioned at the front peripheral surfaces of the sections 122, which represent the outer radial position of the mold cavities 120 in this example. FIG. 3A thus illustrates an example wherein groups of mold cavities 120 are arranged at respective planes (imaginary planes on which the various sections 122 are positioned) in the mold 102, and wherein mold cavities 120 at one plane are aligned with mold cavities 120 at an adjacent plane in a direction perpendicular to the planes. Alternatively, groups of mold cavities 120 can be arranged at respective planes in the mold 102, wherein mold cavities 120 at one plane are staggered relative to mold cavities at an adjacent plane so as to not be aligned in a direction perpendicular to the planes. Such an exemplary configuration is shown in FIG. 3B, where mold cavities 120 of adjacent sections 122 are staggered relative to one another, as shown by the staggered dotted circles positioned at the front peripheral surfaces of the sections 122, which represent the outer radial position of the mold cavities 120 in this example.

In the examples of FIGS. 1, 2, 3A and 3B, the runner passages 126 are positioned along center lines of the mold cavities 120. However, the runner passages 126 could be positioned to be aligned with the tops of the mold cavities 120 or aligned with the bottoms of the mold cavities 120. Moreover, while the runner passages 126 illustrated in FIGS. 1, 2, 3A and 3B are shown as being circular in cross section, the runner passages 126, as well as the mold cavities 120, could have other cross sectional shapes such as square, rectangular or other shapes. In such instances, the runner passage 126 that feeds a given mold cavity 120 could be positioned above the mold cavity 120 or below the mold cavity 120 in the vertical direction so as to feed the mold cavity from the top or bottom, respectively.

The mold 102 can be machined out of various metals, such as, for example, Cu, Cube, various tool steels such as H13, P20, etc., INCONEL@, stainless steel, and the like. Preferably, the metal for mold 120 should be readily Machine able and should have a thermal conductivity and heat capacity on the order of the exemplary metal materials listed above so as to be able to readily remove heat from the molten alloy 134 in the mold cavities 102. In particular, the mold may be configured to cool the molten alloy 134 at a rate sufficient to solidify the molten alloy 134 in the mold cavities 102 into a bulk amorphous structure. A variety of bulk amorphous alloys are known in the art to be good bulk metallic glass (BMG) formers.

These are alloys which may readily solidify from the melt directly into a bulk amorphous structure at relatively slow critical cooling rates ranging from about 1000 K/sec to 0.1° K/sec. The mold can be configured to cool the molten alloy 134 at a rate sufficient to solidify the molten alloy 134 in the mold cavities 102 into a bulk amorphous structure by using a metal for the mold that has good thermal conductivity (such as noted for the example metals above) and by choosing appropriate sizes for the mold cavities depending upon the BMG being cast. For instance, various BMGs known in the art may be cast at diameters on the order of 1 mm to 10 mm directly from the melt at relatively slow critical cooling rates depending upon the particular BMG composition.

Once a desired BMG composition is chosen for the casting, appropriate sized mold cavities can be chosen commensurate with known diameters obtainable in a full amorphous structure for that composition. Alternatively, suitable mold cavity sizes and shapes to obtain fully amorphous alloy structures can be determined through trial and error testing of mold fabrication metals and mold cavity sizes for desired BMG compositions.

Examples of BMG applicable for casting approaches described herein include Zirconium based BMGs, Titanium-based BMGs, Beryllium containing BMGs, Magnesium-based BMGs, Nickel-based BMGs, and Al-based BMGs, to name a few. Exemplary alloys known by trade names include VITRELOY@ 1, VITRELOY@ 1b, VITRELOY@ 4, VITRELOY@ 105, VITRELOY@ 106, and VITRELOY@ 106A. Further examples include Zr-Ti-Cu-Ni-Be BMGs, such as described in U.S. Pat. No. 5,288,344, the entire contents of which are incorporated herein by reference, and Zr-Cu-Al-Ni BMGs and Zr-Cu-Al-Ni-Nb BMGs, such as described in U.S. Pat. Nos. 6,592,689 and 7,070,665, the entire contents of each of which are incorporated herein by reference. Examples also include Zr-(Ni, Cu, Fe, Co, Mn)-Al BMGs, such as described in U.S. Pat. No. 5,032,196, the entire contents of which are incorporated herein by reference, and alloys described in U.S. Patent Application Publication No. 2011/0163509, the entire contents of which are incorporated herein by reference.

Of course, the approaches described herein are not limited to these examples and may be applied to other BMG compositions as well. Moreover, if fully amorphous castings are not desired, relatively larger mold cavities 102 may be used.

FIG. 4B shows another exemplary mold 102 configuration according to another aspect. As shown in the example of FIG. 4B, the mold 102 may comprise inserts 162 of predetermined desired sizes configured to be positioned in at least some of the plurality of mold cavities 120 for changing sizes of those mold cavities 120. The inserts 162 may be formed in various sizes and of the same metal of which the mold sections 122 are made. The inserts 162 do not become part of the castings formed in the mold cavities 120 but rather are separable from the castings.

In the example of FIG. 4B, the mold cavities 120 are cylindrical, and the inserts 162 are likewise cylindrical of commensurate diameter. By placing the inserts at the end of some or all of the mold cavities 120 during assembly of the mold 102, desired sizes for the mold cavities 120 may be obtained and multiple different sizes of mold cavities 120 may thereby be obtained for the same mold. By removing the inserts 162 after a casting event, the original mold 102 configuration may once again be obtained as shown in FIG. 4A for a next casting event. Of course, the inserts are not limited to the shapes illustrate in FIG. 4B, and any suitable shape for the insert may be used, which can then not only change the size of the cast article, but also may change the shape of the cast article to replicate a desired shape of the insert surface at its contacting surface with the molten alloy.

FIGS. 5A-5C illustrate an example of using a refractory article insert that may be inserted into one or more mold cavities 120 of the reusable metal mold 102 to form an exemplary composite structure comprising a refractory (e.g., ceramic) tube 350 and an alloy such as a bulk metallic glass according to another aspect. FIG. 5A shows a portion of an exemplary mold 102 configuration like that of FIG. 4A, wherein a refractory article, e.g., a ceramic member in the shape of a cylindrical tube 350 with an opening or channel 352 there through, may be provided in mold cavity 120. FIG. 5B shows the refractory article 350 positioned in multiple mold cavities, e.g., the two lower mold cavities 120. During a casting process, molten alloy 134 contacts the refractory article 350 positioned in the corresponding mold cavity 120, passes into and through the opening 352, and solidifies to form a composite structure 350 a as illustrated in FIG. 5C. The composite structure 350 a comprises an alloy 354, e.g., a bulk metallic glass, in the opening 352 in contact with the refractory tube 350. The composite structure 350 a may thereby form bulk metallic glass conductor 354 extending through the cylindrical ceramic tube 350.

Mold cavities of a variety sizes and shapes may be used. According to certain examples, where fully amorphous cast BMG articles are desired, the diameters of the mold cavities 120 may range from less than 1 mm up to about 10 mm. For castings of alloy feedstock that do not need to be fully amorphous in structure, mold cavities may be even larger in diameter, e.g., 2 cm, 3 cm, 4 cm, 5 cm or more. As shown in FIGS. 1, 2, 3A and 3B, the mold cavities 120 may by cylindrical in shape, and exemplary dimensions for casting fully amorphous BMG cylindrical slugs include diameters in the range of about 1-10 mm and preferably in the range of about 4-10 mm, with lengths in the range of about 5-100 mm and preferably in the range of about 30-55 mm. Of course, the present disclosure is not limited to these exemplary ranges.

In addition, while FIGS. 1, 2, 3A and 3B illustrate cylindrically shaped mold cavities 120, mold cavities of other shapes could be utilized according to the present disclosure. Other exemplary shapes include rectangular solids, triangular solids, hexagonal solids, and more complicated shapes that can be suitably machined into the mold 102, either with or without metal mold inserts to define desired interior surface structure of the mold cavity to be replicated in the cast article. For instance, mold cavities 120 could be suitably machined to provide for the casting of near-net shape articles such as disk springs, ring structures, golf-club-face inserts, jewelry items, consumer electronics casings, etc.

Referring again to FIG. 1, the overall size of the mold 102 and other components of the counter gravity casting apparatus 100 can be chosen to be quite large consistent with commercial manufacturing needs. For instance, the mold could be designed to cast hundreds or thousands of articles in a single mold in a single casting event (e.g., 500-3000 articles) of the exemplary sizes noted above. Exemplary molds may range from about 0.5 to 2 feet in diameter and from about 0.5 to 5 feet in height. The number of sections, e.g., metal plates, may range from 2 to 30 sections, for example. Of course, the present disclosure is not limited to these examples.

The crucible (e.g., boron nitride crucible) may be designed, for instance, to contain hundreds or thousands of pounds of molten alloy, e.g., 5000 pounds. To increase throughput, in some embodiments, the apparatus 100 may be modified so as to divide the vacuum chamber 140 into a first upper chamber section and a second lower chamber section, such that multiple mold assemblies may be positioned on a rotary stage, each with an associated upper chamber section, so that when one mold is filled with molten alloy for a casting event, the upper chamber section containing that mold assembly may then be separated from the lower chamber section containing the crucible, and the upper chamber section having the filled mold can be moved out of the way, and another upper chamber section having another mold assembly may take the place of the prior upper chamber section. A suitable gate valve may be used to isolate the crucible containing molten alloy from ambient air during placement of the next mold assembly. Alternatively, mold assemblies including the mold 102 and feed tube 104 could be shuttled in and out of a first vacuum chamber section that is separate from a second vacuum chamber section containing the crucible 130 through a suitably sized airlock, wherein the first and second vacuum chamber sections may be isolated from one another via a gate valve.

Also, a metal mold according to the present disclosure need not be comprised entirely of metal, and it is possible that a metal mold according to the present disclosure may include in its structure other types of materials such as polymers (e.g., seals), insulating materials, etc. A metal mold according to the present disclosure is still considered a metal mold even if it is comprised of other materials to the extent that the mold is predominantly metal by comprising more than half metal by volume or weight.

An exemplary method for counter gravity casting will now be described. FIG. 6 illustrates a flow diagram for an exemplary method 400. Initially, a mold 102 and crucible 130 can be arranged as illustrated in FIG. 1 with various other components of the system100 shown therein. The crucible can then be charged with the desired metal constituents to melt a desired alloy, e.g., constituents for a bulk metallic glass (BMG) forming alloy. Melting the alloy in the first instance in a section of the counter gravity casting apparatus 100 can be beneficial because it can permit the molten alloy 134 to be cast directly from that initial melt, thereby reducing the number of overall steps in the casting process and enhancing efficiency and cost effectiveness.

At step 402, the chamber 140 can then be evacuated, backfilled with inert gas, e.g., argon gas, and evacuated again to purge gas impurities. This can be repeated several times, and the crucible can then be heated, e.g., with induction heating, so melt the constituents under vacuum or under inert gas to produce the molten alloy 134. At this point, the chamber 140 can be placed under a desired pressure of argon or desired inert gas so as to prevent undesired evaporation of the molten alloy. While FIG. 1 illustrates the mold 102 and the crucible 130 in one (i.e., the same) chamber 140, the mold 102 and the crucible 130 could be situated in separate vacuum chambers that communicate with one another via a gate value. For instance, the crucible 130 could be situated in one vacuum chamber a pressure, e.g., 5 psi, and the mold 102 could be situated in a separate vacuum chamber and brought to the same pressure, e.g., 5 psi.

Each such vacuum chamber can have its own suitable vacuum plumbing, values, pressure sensors and vacuum pumps, etc. The vacuum chamber containing the mold 102 and the separate vacuum chamber containing the crucible 130 need not be brought to the same pressure level at the same time, but they should be brought to the same pressure level just prior to the opening of the gate valve that separates the two separate chambers for a casting event.

As described previously herein in connection with FIG. 1, the chamber 140 comprises a reusable metal mold 102 and a crucible 130 containing a molten alloy 134. The mold comprises a plurality of mold cavities 120 arranged among multiple separable metal sections 122 fed by sprue(s) 124 and runner passages 126, such as previously described. Though these features are referenced with regard to reference numerals from FIG. 1 for brevity and convenience, it should be appreciated that method 400 is applicable to all variations and examples noted in the present disclosure.

At step 404, the feed tube 104 can be immersed in the molten alloy 134 by changing a relative distance between the mold 102 and the crucible 130 as previously described. At step 406, a sub-ambient pressure can be applied to the interior of the mold 102, e.g., by lowering the pressure in the interior of the mold via the vacuum tube 108 by opening a vacuum valve to communicate with a vacuum system, optionally with the aid of a suitable gas controller to provide a sub-ambient pressure that is at an intermediate pressure higher than that of a full vacuum.

At step 408 a pressure differential is applied between the interior of the mold 102 and a surface of the molten alloy 134 to feed the molten alloy 134 upward through the feed tube 104 from the crucible 130 and into the reusable metal mold 102 and into the plurality of mold cavities 120 under the pressure differential generated at least partially by the sub-ambient pressure at the interior of the mold 102. This can be accomplished as a direct result of step 406 if the pressure in the vacuum chamber is held at a higher value than the pressure inside the mold 102 when step 406 is carried out.

Or, if the same sub-ambient pressure exists both in the chamber 140 and in the mold 102 during step 404, step 406 can be accomplished by increasing a pressure of inert gas in the chamber via valve 144 so that the gas pressure at the surface of the the molten alloy 134 is greater than the pressure inside the mold 102. Regardless, pressure differential can be applied by any suitable control of both vacuum hardware and gas flow hardware while monitoring pressure via suitable pressure sensors as discussed previously.

It will be appreciated that the pressure differential applied in step 408 will directly correlate with a height of the column of molten alloy that is drawn up into the feed tube 104 and mold 102, given the known density of the molten alloy. For various BMGs of the type previously mentioned herein, a 5 psi pressure differential can raise a column of molten alloy in a feed tube 50 mm in diameter to a height of about 60 cm, for example.

Once the pressure differential is applied, the molten alloy will quickly and steadily rise into the mold without turbulence so as to fill the mold cavities. Trial and error testing can be used to determine the time that it takes for a molten alloy 134 to fill a mold 102 of a given configuration.

At step 410 the molten alloy 134 in the mold cavities 120 of the mold 102 is cooled at a rate sufficient to solidify the molten alloy 134 in the mold cavities 120 into cast articles having a bulk amorphous structure while at least some of, e.g., a substantial portion of, the molten alloy 134 disposed within the sprue 124 remains in a molten state. In some examples, solidification of the molten alloy 134 (e.g., cooling below the solidus temperature or the glass transition temperature Tg) may occur within several seconds to several tens of seconds of filling the mold cavities 120, depending upon conditions, at which time at least some of the alloy, e.g., a majority of the alloy, contained within the central sprue 124 will still be in a molten state. A portion of the alloy being cast may form a thin solidified shell on the wall of the sprue 124, and this will not interfere with the ability to return the majority of the molten alloy 134 remaining in the sprue 124 back to the crucible 130. Trial and error testing can be used to determine suitable target values for the temperature of the molten alloy 134 in the crucible 130, suitable target values for the temperatures at various locations of the mold 102, suitable levels of cooling desired for various regions of the mold 102, suitable target values for the pressure differential, and suitable values for the sizes of the mold cavities 120, so as to achieve the desired rate of cooling of the alloy 134 in the mold cavities 120 and, if desired, to achieve an amorphous structure for the cast alloy, while maintaining at least some of the alloy 134 in a molten state in the sprue 124.

At step 412, the pressure differential can be released to permit the molten alloy 134 disposed within the sprue 124 to return to the crucible 130 under the force of gravity, thereby conserving material to provide a cost efficient process. As discussed previously, the feed tube 104 can then be removed from the crucible 130, and a movable lid 138 can then cover the exposed portion of the molten alloy 134 in the crucible to prevent contamination of the alloy 134. At step 414, the cast articles can be removed from the mold 102 such as previously described. The apparatus can then be readied for a next casting event.

Claims

WE CLAIM

1) Our Invention "ICS- Counter Gravity Casting" is a counter gravity casting apparatus includes a reusable metal mold having a plurality of mold cavities, a feed tube configured to feed molten alloy into the mold, and a vacuum fitting configured to permit a vacuum to be applied to the mold. The Invented technology also includes a multiple metal sections configured such that adjacent metal sections mate to one another, the metal sections being separable from one another and the metal sections include recesses that form the mold cavities, and the mold includes a sprue and multiple runner passages. The invented technology is also sprue is configured to receive molten alloy from the feed tube and the multiple runner passages are configured to feed molten alloy from the sprue to the mold cavities and the methods of casting bulk amorphous alloy articles or feedstock is described. The Invented technology also includes the vacuum, counter gravity casting of molten metal includes a bottom drag member and a casting mold member thereon engaged together at a parting plane. The Invented technology also a valve member is disposed adjacent the parting plane in an in gate to a mold cavity formed at least in part in the casting mold member and is movable between a valve seat on the bottom drag member and a stop surface on the casting mold member to permit filling of the mold cavity in counter gravity manner from an underlying molten metal pool when the bottom drag member is immersed therein and to prevent backflow of the molten metal from the mold cavity when the bottom drag member is withdrawn from the pool after mold filling and before solidification of the molten metal in the mold cavity.

2) According to claims# the invention is a counter gravity casting apparatus includes a reusable metal mold having a plurality of mold cavities, a feed tube configured to feed molten alloy into the mold, and a vacuum fitting configured to permit a vacuum to be applied to the mold.

3) According to claiml,2# the invention is a multiple metal sections configured such that adjacent metal sections mate to one another, the metal sections being separable from one another and the metal sections include recesses that form the mold cavities, and the mold includes a sprue and multiple runner passages.

4) According to claiml,2,3# the invention is a configured to receive molten alloy from the feed tube and the multiple runner passages are configured to feed molten alloy from the sprue to the mold cavities and the methods of casting bulk amorphous alloy articles or feedstock is described.

5) According to claiml,2,4# the invention is a vacuum, counter gravity casting of molten metal includes a bottom drag member and a casting mold member thereon engaged together at a parting plane.

6) According to claiml,3,5# the invention is a valve member is disposed adjacent the parting plane in an in gate to a mold cavity formed at least in part in the casting mold member and is movable between a valve seat on the bottom drag member and a stop surface on the casting mold member to permit filling of the mold cavity in counter gravity manner from an underlying molten metal pool when the bottom drag member is immersed therein and to prevent backflow of the molten metal from the mold cavity when the bottom drag member is withdrawn from the pool after mold filling and before solidification of the molten metal in the mold cavity.

FIG. 5C ILLUSTRATES AN EXEMPLARY CERAMIC COMPOSITE ARTICLE WITH A BULK METALLIC GLASS PORTION RESULTING FROM A CASTING PROCESS USING THE MOLD AND CERAMIC INSERT OF FIG. 5B. 2021100090