CA1233307A - Method and apparatus for making alloy powder - Google Patents
Method and apparatus for making alloy powderInfo
- Publication number
- CA1233307A CA1233307A CA000456271A CA456271A CA1233307A CA 1233307 A CA1233307 A CA 1233307A CA 000456271 A CA000456271 A CA 000456271A CA 456271 A CA456271 A CA 456271A CA 1233307 A CA1233307 A CA 1233307A
- Authority
- CA
- Canada
- Prior art keywords
- alloy
- hearth
- molten
- powder
- fluid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
- B22F2009/0848—Melting process before atomisation
- B22F2009/0856—Skull melting
Abstract
METHOD AND APPARATUS FOR MAKING ALLOY POWDER
ABSTRACT OF THE DISCLOSURE
An improved method for making a metal powder employs improved apparatus comprising, in combination, a fluid-cooled hearth for receiving metallic material which defines an alloy and which is to be melted, a plasma heat source adapted to melt the metallic material, a powder metal producer, and means to introduce the molten metallic material from the hearth into the powder metal producer.
The fluid-cooled walls of the hearth resolidify a portion of the molten metallic material to form a skull as a barrier between the hearth and additional molten alloy produced within the hearth. This method and apparatus restricts introduction of impurities into the molten alloy which is later introduced into the powder metal producer. In one form, a fluid-cooled pouring trough, as a stream control device, can be disposed between the hearth and the powder producer to receive molten metal from the hearth and to introduce it into the powder metal producer.
ABSTRACT OF THE DISCLOSURE
An improved method for making a metal powder employs improved apparatus comprising, in combination, a fluid-cooled hearth for receiving metallic material which defines an alloy and which is to be melted, a plasma heat source adapted to melt the metallic material, a powder metal producer, and means to introduce the molten metallic material from the hearth into the powder metal producer.
The fluid-cooled walls of the hearth resolidify a portion of the molten metallic material to form a skull as a barrier between the hearth and additional molten alloy produced within the hearth. This method and apparatus restricts introduction of impurities into the molten alloy which is later introduced into the powder metal producer. In one form, a fluid-cooled pouring trough, as a stream control device, can be disposed between the hearth and the powder producer to receive molten metal from the hearth and to introduce it into the powder metal producer.
Description
; by 3 3 (3 J
METHOD AND APPARATUS FOX MAKING ALLOY POWDER
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to the manufacture of alloy powder, and, more particularly, to the manufacture of a superalloy powder characterized by reduced amounts of impurities.
METHOD AND APPARATUS FOX MAKING ALLOY POWDER
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to the manufacture of alloy powder, and, more particularly, to the manufacture of a superalloy powder characterized by reduced amounts of impurities.
2. Description of the Prior Art A wide variety of alloy powder manufacturing methods and apparatus are well known in the metallurgical art. As such manufacture relates to high temperature alloys and superalloy, for example the type based on Fe, Co, Nix To or their combinations, current powder production methods include first melting the alloy elements in a high vacuum furnace chamber through the use of vacuum electron beam, vacuum arc, vacuum induction or vacuum plasma melting to produce an ingot. After production of the alloy ingot, current powder production converts the alloy ingot into powder by such methods as gas atomization, rotary atomization and vacuum atomization utilizing ceramic hearth primary melting in conjunction with a ceramic tundish and nozzle for producing a liquid metal stream needed to produce powder.
Certain high temperature operating and highly stressed components of gas turbine engines, for example, turbine disks, use powder metal in their manufacture.
By producing a powder metal preform nearly to the final shape of the component, manufacturing costs can be ~,~333~1t7 reduced. However, it has been recognized that inadequate powder cleanliness, particularly from ceramic particles introduced in currently used powder manufacturing processes, can result in a significant reduction in such mechanical properties as low cycle fatigue in the finished component. This reduction is due to the presence in the consolidated powder metal disks of defects which act as initiation sites for low cycle fatigue failures. Nearly all superalloy powder metal for such applications currently are produced by first providing an ingot, melting the ingot and then making powder by gas atomization processes. Such atomization processes utilize ceramic melting and pouring devices and it has been found that these devices introduce a significant proportion of the undesirable ceramic inclusions. It should be recognized that the present invention can be particularly useful when the starting materials are relatively free of such ceramic inclusions.
SUMMARY OF THY INVENTION
It is a principal object of the present invention to provide an improved method for making an alloy powder in which the melting is conducted without contact with ceramic members and powder is made directly from the molten alloy.
Another object is to provide apparatus for producing an alloy powder, improved through a means to melt the metallic materials of the alloy out of contact with ceramic members.
These and other objects and advantages will be Gore clearly understood from the following detailed description of the preferred embodiments and the drawing all of which are intended to be typical of rather than in any way limiting on the scope of the present invention.
Briefly, the method of the present invention, in one form, provides a melting hearth having fluid-cooled walls and in which is disposed the metallic material which define an alloy composition. The metallic material is then melted in the hearth. In one specific embodiment, a plasma heat source is directed a-t and may be swept over the metallic material and the hearth -to provide substantially uniform heat to the metallic material to initiate and conduct melting of the metallic material. While melting is conducted, a cooling fluid is provided in the walls of the hearth sufficient to resolidify melted metallic material adjacent to the cooled hearth walls. This forms a skull of metallic material within the hearth a-t the cooled walls while maintaining additional molten alloy as a molten metal reservoir within the skull. Then the additional molten alloy is introduced from the hearth into a powder metal producer One form of the apparatus of the present invention provides, in combination, means to melt the metallic material comprising a fluid-cooled hearth for receiving metallic material, a plasma heat source to melt -the metallic material in the hearth and to provide a molten metal reservoir, a powder metal producer, and means to introduce the molten metal prom the reservoir into the powder metal producer. In one form, the means to melt the metallic material is a movable plasma heat source directed toward the hearth and adapted, during operation, to sweep a surface of metallic material in the hearth to provide substantially uniform heat to the metallic material.
BRIEF DESCRIPTION OF THE DRAWING
The drawing is a partially sectional, diagrammatic view of one form of the present invention including an improved melt chamber and a metallic powder producer.
DESCRIPTION Ox TIE PREFERRED EMBODIMENTS
_ _ The development of modern aircraft gas turbine engines has defined requirements for higher temperature operating materials capable of withstanding high stresses.
The complexity of component design and the advances in 33~'~
powder metallurgy processing and alloy definition have made the use of powder metal attractive from an economic manufacturing viewpoint. In addition, powder alloy use has the capability of achieving desirable properties such as low cycle fatigue resistance along with high temperature operating capability.
Typical of such a component requiring very high strength, high temperature materials are rotating disks used in the turbine section of modern gas turbine engines.
Other engine components, such as of Tubs alloys, sometimes are used in the compressor section. However, in order to achieve desirable low cycle fatigue capability, it has been recognized that certain types of impurities must be eliminated from the powder alloy used in such processing.
It has been observed that a major impurity which results in defects in such disks is ceramic in nature and can be traced to initial starting material or the subsequent processing required to produce powder from the alloy. The presence of such defects can reduce the low cycle fatigue capability of such disks below that required under high temperature and high stress conditions.
For the production of powder metal from superalloy, for example of the type based on Fe, Co, No I or their combinations, gas atomization processes are used with ceramic melting and pouring devices. Such ceramic structures introduce a significant portion of the ceramic impurity material which constitutes defects serving as low cycle fatigue fracture initiation sites in the finished component manilfactured by powder metallurgy techniques.
The present invention avoids contact between ceramic members and the alloy from which the powder is manufactured by melting metallic material, out of contact with ceramic members and introducing that molten alloy into a powder metal producer. In one form, this is accomplished by the combination of the use of a fluid-cooled melting hearth and a plasma heat source which may be movable, in the melt chamber or melting apparatus in which the materials of the alloy are melted prior to introduction into a powder metal producer. The fluid-cooled hearth causes resolidification of molten material in the hearth about the walls of the hearth. This forms a hearth skull of metallic materials as a barrier between material of the hearth and the molten alloy remaining in the hearth skull.
Use of a movable plasma heat source, such as one or more movable plasma torches which together define the plasma heat source, provides rapid and uniform heating and melting of the materials defining the composition of the alloy to be made into powder. In addition, superheating of the molten material to a temperature sufficient and practical for introduction into a metal powder producer can be assisted through the use of such movable, primary plasma heat source which is adapted to sweep over a surface of the metallic material in the hearth.
One form of the apparatus of the present invention it shown in the drawing. The improved means to melt the metallic material in melting chamber 10 includes a fluid-cooled hearth 12 including walls 13 having fluid-cooling passages 14 therein connected with a source of cooling fluid such as water (not shown. As used herein, the term "wall" or "walls" may include the base or floor as well as the side walls, as desired, of the member being described. Melting chamber I can be adapted to enclose a desired atmosphere or pressure condition for example by introducing an inert gas such as argon into inlet 16, to be evacuated through gas outlet 18.
Appropriate other means to control the atmosphere within melt chamber 10 will be recognized by those skilled in the art, according to a variety of methods currently used.
Disposed above hearth 12 is a plasma heat source 20 shown ~;333~'~
in the drawing as a plurality of plasma torches, which may be movable, directed toward hearth 12. With metallic material 22 introduced in the hearth 12, plasma heat source 20 is adapted to initiate and further -the melting of such materials. When movable, plasma heat source 20 is adapted to sweep over a surface of the metallic material and to provide substantially uniform heat to such material.
During the operation of the above-dessribed improved melting means, metallic material 22, which defines an alloy composition, is disposed in hearth 12. Such introduction can be in a batch-type process or can be in a continuous or semi-continuous process employing a supplementary metal feed system of a type well known in the art. For example, a chute and feed mechanism of the type shown in US. Patent 3,744,943 - Bomberger, Jr. et at issued July 10, 1973 can be used.
I1~ith cooling fluid such as water circulating within cooling passages 14, plasma heat source 20 such as a battery of movable plasma heat torches are placed in operation. In this embodiment, the torches are moved to sweep a surface o-E the material 22 in hearth 12 to melt such material. As molten material contacts the cooled inner wall of hearth 12, such material resolidifies into a hearth skull 24 which acts as a barrier or buffer between the hearth walls and other melted material and alloy in the hearth. In this way, hearth material is prohibited from being introduced into the molten alloy within the hearth and a reservoir of molten alloy is provided substantially free of foreign materials.
After a desirable level of melting and superheat is achieved, the hearth is tipped such as about pivot 26 using a tipping means or mechanism represented by arrow 28.
Molten alloy in the hearth, remaining from that material which is resolidified to form skull 24, is discharged or poured from the hearth, conveniently from a hearth lip 30 to provide a molten metal stream 32. In the drawing, ~3~33~79 according to one form of the present invention, molten metal stream 32 is poured into a stream control device in the form of a fluid-cooled trough 34 for supplemental handling. however, it should be understood that molten metal stream 32 can be introduced into any of several other stream control devices of a type apparent to those skilled in the art or directly into a powder metal producer.
In the form of the invention shown in the drawing, molten metal stream 32 is introduced into a stream control device comprising fluid-cooled trough 34 which includes fluid-cooling passages 36 supplied from a cooling fluid source such as water (snot shown) in a manner well known in the art. Similar to -the hearth 12, trough 34 can include a lip 38 to assist flow of molten metal from trough 34.
In operation, trough 34 receives molten alloy in stream 32 from hearth 12 while cooling fluid is circulated through cooling passages 36. As the molten metal contacts the fooled walls of the trough, a portion of the molten metal solidifies forming a trough skull 40 similar to hearth skull 24. Skull 40 -functions, in the same manner, as a barrier or buffer between walls of the trough and molten alloy maintained in the trough after solidification of the trough skull. To maintain such additional alloy in the trough in the molten state, a secondary plasma heat source such as shown in the drawing as a plasma heat torch 42 may be desired or required. During operation, secondary plasma heat source 42 is directed at the additional molten alloy in the trough remaining from that which has resolidified as trough skull 40. A stream 44 of molten alloy flows from trough 34 into a powder metal producer shown generally at 46 in the drawing. the stream of molten alloy is converted from the liquid phase to a powder in the powder metal producer 46.
Such a metal powder producer can be of a variety
Certain high temperature operating and highly stressed components of gas turbine engines, for example, turbine disks, use powder metal in their manufacture.
By producing a powder metal preform nearly to the final shape of the component, manufacturing costs can be ~,~333~1t7 reduced. However, it has been recognized that inadequate powder cleanliness, particularly from ceramic particles introduced in currently used powder manufacturing processes, can result in a significant reduction in such mechanical properties as low cycle fatigue in the finished component. This reduction is due to the presence in the consolidated powder metal disks of defects which act as initiation sites for low cycle fatigue failures. Nearly all superalloy powder metal for such applications currently are produced by first providing an ingot, melting the ingot and then making powder by gas atomization processes. Such atomization processes utilize ceramic melting and pouring devices and it has been found that these devices introduce a significant proportion of the undesirable ceramic inclusions. It should be recognized that the present invention can be particularly useful when the starting materials are relatively free of such ceramic inclusions.
SUMMARY OF THY INVENTION
It is a principal object of the present invention to provide an improved method for making an alloy powder in which the melting is conducted without contact with ceramic members and powder is made directly from the molten alloy.
Another object is to provide apparatus for producing an alloy powder, improved through a means to melt the metallic materials of the alloy out of contact with ceramic members.
These and other objects and advantages will be Gore clearly understood from the following detailed description of the preferred embodiments and the drawing all of which are intended to be typical of rather than in any way limiting on the scope of the present invention.
Briefly, the method of the present invention, in one form, provides a melting hearth having fluid-cooled walls and in which is disposed the metallic material which define an alloy composition. The metallic material is then melted in the hearth. In one specific embodiment, a plasma heat source is directed a-t and may be swept over the metallic material and the hearth -to provide substantially uniform heat to the metallic material to initiate and conduct melting of the metallic material. While melting is conducted, a cooling fluid is provided in the walls of the hearth sufficient to resolidify melted metallic material adjacent to the cooled hearth walls. This forms a skull of metallic material within the hearth a-t the cooled walls while maintaining additional molten alloy as a molten metal reservoir within the skull. Then the additional molten alloy is introduced from the hearth into a powder metal producer One form of the apparatus of the present invention provides, in combination, means to melt the metallic material comprising a fluid-cooled hearth for receiving metallic material, a plasma heat source to melt -the metallic material in the hearth and to provide a molten metal reservoir, a powder metal producer, and means to introduce the molten metal prom the reservoir into the powder metal producer. In one form, the means to melt the metallic material is a movable plasma heat source directed toward the hearth and adapted, during operation, to sweep a surface of metallic material in the hearth to provide substantially uniform heat to the metallic material.
BRIEF DESCRIPTION OF THE DRAWING
The drawing is a partially sectional, diagrammatic view of one form of the present invention including an improved melt chamber and a metallic powder producer.
DESCRIPTION Ox TIE PREFERRED EMBODIMENTS
_ _ The development of modern aircraft gas turbine engines has defined requirements for higher temperature operating materials capable of withstanding high stresses.
The complexity of component design and the advances in 33~'~
powder metallurgy processing and alloy definition have made the use of powder metal attractive from an economic manufacturing viewpoint. In addition, powder alloy use has the capability of achieving desirable properties such as low cycle fatigue resistance along with high temperature operating capability.
Typical of such a component requiring very high strength, high temperature materials are rotating disks used in the turbine section of modern gas turbine engines.
Other engine components, such as of Tubs alloys, sometimes are used in the compressor section. However, in order to achieve desirable low cycle fatigue capability, it has been recognized that certain types of impurities must be eliminated from the powder alloy used in such processing.
It has been observed that a major impurity which results in defects in such disks is ceramic in nature and can be traced to initial starting material or the subsequent processing required to produce powder from the alloy. The presence of such defects can reduce the low cycle fatigue capability of such disks below that required under high temperature and high stress conditions.
For the production of powder metal from superalloy, for example of the type based on Fe, Co, No I or their combinations, gas atomization processes are used with ceramic melting and pouring devices. Such ceramic structures introduce a significant portion of the ceramic impurity material which constitutes defects serving as low cycle fatigue fracture initiation sites in the finished component manilfactured by powder metallurgy techniques.
The present invention avoids contact between ceramic members and the alloy from which the powder is manufactured by melting metallic material, out of contact with ceramic members and introducing that molten alloy into a powder metal producer. In one form, this is accomplished by the combination of the use of a fluid-cooled melting hearth and a plasma heat source which may be movable, in the melt chamber or melting apparatus in which the materials of the alloy are melted prior to introduction into a powder metal producer. The fluid-cooled hearth causes resolidification of molten material in the hearth about the walls of the hearth. This forms a hearth skull of metallic materials as a barrier between material of the hearth and the molten alloy remaining in the hearth skull.
Use of a movable plasma heat source, such as one or more movable plasma torches which together define the plasma heat source, provides rapid and uniform heating and melting of the materials defining the composition of the alloy to be made into powder. In addition, superheating of the molten material to a temperature sufficient and practical for introduction into a metal powder producer can be assisted through the use of such movable, primary plasma heat source which is adapted to sweep over a surface of the metallic material in the hearth.
One form of the apparatus of the present invention it shown in the drawing. The improved means to melt the metallic material in melting chamber 10 includes a fluid-cooled hearth 12 including walls 13 having fluid-cooling passages 14 therein connected with a source of cooling fluid such as water (not shown. As used herein, the term "wall" or "walls" may include the base or floor as well as the side walls, as desired, of the member being described. Melting chamber I can be adapted to enclose a desired atmosphere or pressure condition for example by introducing an inert gas such as argon into inlet 16, to be evacuated through gas outlet 18.
Appropriate other means to control the atmosphere within melt chamber 10 will be recognized by those skilled in the art, according to a variety of methods currently used.
Disposed above hearth 12 is a plasma heat source 20 shown ~;333~'~
in the drawing as a plurality of plasma torches, which may be movable, directed toward hearth 12. With metallic material 22 introduced in the hearth 12, plasma heat source 20 is adapted to initiate and further -the melting of such materials. When movable, plasma heat source 20 is adapted to sweep over a surface of the metallic material and to provide substantially uniform heat to such material.
During the operation of the above-dessribed improved melting means, metallic material 22, which defines an alloy composition, is disposed in hearth 12. Such introduction can be in a batch-type process or can be in a continuous or semi-continuous process employing a supplementary metal feed system of a type well known in the art. For example, a chute and feed mechanism of the type shown in US. Patent 3,744,943 - Bomberger, Jr. et at issued July 10, 1973 can be used.
I1~ith cooling fluid such as water circulating within cooling passages 14, plasma heat source 20 such as a battery of movable plasma heat torches are placed in operation. In this embodiment, the torches are moved to sweep a surface o-E the material 22 in hearth 12 to melt such material. As molten material contacts the cooled inner wall of hearth 12, such material resolidifies into a hearth skull 24 which acts as a barrier or buffer between the hearth walls and other melted material and alloy in the hearth. In this way, hearth material is prohibited from being introduced into the molten alloy within the hearth and a reservoir of molten alloy is provided substantially free of foreign materials.
After a desirable level of melting and superheat is achieved, the hearth is tipped such as about pivot 26 using a tipping means or mechanism represented by arrow 28.
Molten alloy in the hearth, remaining from that material which is resolidified to form skull 24, is discharged or poured from the hearth, conveniently from a hearth lip 30 to provide a molten metal stream 32. In the drawing, ~3~33~79 according to one form of the present invention, molten metal stream 32 is poured into a stream control device in the form of a fluid-cooled trough 34 for supplemental handling. however, it should be understood that molten metal stream 32 can be introduced into any of several other stream control devices of a type apparent to those skilled in the art or directly into a powder metal producer.
In the form of the invention shown in the drawing, molten metal stream 32 is introduced into a stream control device comprising fluid-cooled trough 34 which includes fluid-cooling passages 36 supplied from a cooling fluid source such as water (snot shown) in a manner well known in the art. Similar to -the hearth 12, trough 34 can include a lip 38 to assist flow of molten metal from trough 34.
In operation, trough 34 receives molten alloy in stream 32 from hearth 12 while cooling fluid is circulated through cooling passages 36. As the molten metal contacts the fooled walls of the trough, a portion of the molten metal solidifies forming a trough skull 40 similar to hearth skull 24. Skull 40 -functions, in the same manner, as a barrier or buffer between walls of the trough and molten alloy maintained in the trough after solidification of the trough skull. To maintain such additional alloy in the trough in the molten state, a secondary plasma heat source such as shown in the drawing as a plasma heat torch 42 may be desired or required. During operation, secondary plasma heat source 42 is directed at the additional molten alloy in the trough remaining from that which has resolidified as trough skull 40. A stream 44 of molten alloy flows from trough 34 into a powder metal producer shown generally at 46 in the drawing. the stream of molten alloy is converted from the liquid phase to a powder in the powder metal producer 46.
Such a metal powder producer can be of a variety
3~t7 of types well known in the art, for example atomization or other disintegration type devices which produce metal powders. The drawing shows diagrammatically one of -the gas atomization type which includes a cooling tower I
having a molten metal inlet 50 about which is disposed an atomizing gas spray means 52 to inject atomizing gas such as argon, nitrogen, helium, etc., into molten metal stream 44 entering cooling tower 48 through inlet 50.
Such an atomizing gas is fed through conduit 54 from a pressurized gas source (not shown). The atomizing gas thus introduced into the molten alloy stream causes the stream to disperse into small particles which solidify and fall to the bottom of cooling tower 48 to be collected in metal powder collector 56. As shown in the drawing, it is convenient to include with such a powder metal producer an exhaust system shown at 58. Conrail the exhaust system includes a fines or dust collector 60, for example of the cyclone collector type well known in the art.
If desired, supplemental heat sources can be used in melting chamber 10, for example directed at hearth lip 30 or at trough lip 38, or boil. This can assist molten alloy streams such as 32 and 44 to pour in a desired molten condition or superheat.
In one example of the evaluation of the improved melt chamber or means to melt the metallic material of the present invention, a nickel-base superalloy by commercially available as Rune 95 alloy and having a nominal composition, by weight, of Q.06% C, 13% Or, 8% Co, 3.5% Mow 3.5% Cub, 0.05% Or, 2.5% Tip 3.5% Al, 0.01%B, 3.5~ W with the balance No and incidental impurities was used. In this evaluation, three plasma heat torches as the primary heat source 20 were focused on a water-cooled copper melting hearth 12. An additional plasma heat torch as a secondary plasma heat source 42 can be focused on a water-cooled copper pouring trough 34, as shown in the drawing. In other evaluations of melting in hearth 12, t' _ g _ fewer than three torches were used. The hearth heating torches, as the primary plasma heat source, were movable in three orthogonal directions; the pouring trough heating torch or secondary plasma heat source was movable in the vertical and one horizontal direction. The sides of the apparatus and the supports for the plasma torches were protected by heat shields. As a result of several trial evaluations, it was found that the combination of a fluid-cooled hearth and a plasma heat source, which may be movable, alone or in combination with a pouring trough as a stream control device, can provide an improved means to melt a metallic material for the purpose of producing a powder metal and without a substantial increase of ceramic impurities which can act as defect sites.
Through -the use of the apparatus of the present invention, there is provided an improved method for making an alloy powder, especially one of a hick temperature alloy or superalloy such as based on Fe, Jo, Nix To or their mixtures, the method being characterized by the substantial avoidance of addition of defect-forming ceramic materials.
This invention has been described in connection with specific embodiments and examples. However, it will be readily recognized by those skilled in the art the various modifications and variations of which the present invention is capable without departing from its scope as represented by the appended claims.
having a molten metal inlet 50 about which is disposed an atomizing gas spray means 52 to inject atomizing gas such as argon, nitrogen, helium, etc., into molten metal stream 44 entering cooling tower 48 through inlet 50.
Such an atomizing gas is fed through conduit 54 from a pressurized gas source (not shown). The atomizing gas thus introduced into the molten alloy stream causes the stream to disperse into small particles which solidify and fall to the bottom of cooling tower 48 to be collected in metal powder collector 56. As shown in the drawing, it is convenient to include with such a powder metal producer an exhaust system shown at 58. Conrail the exhaust system includes a fines or dust collector 60, for example of the cyclone collector type well known in the art.
If desired, supplemental heat sources can be used in melting chamber 10, for example directed at hearth lip 30 or at trough lip 38, or boil. This can assist molten alloy streams such as 32 and 44 to pour in a desired molten condition or superheat.
In one example of the evaluation of the improved melt chamber or means to melt the metallic material of the present invention, a nickel-base superalloy by commercially available as Rune 95 alloy and having a nominal composition, by weight, of Q.06% C, 13% Or, 8% Co, 3.5% Mow 3.5% Cub, 0.05% Or, 2.5% Tip 3.5% Al, 0.01%B, 3.5~ W with the balance No and incidental impurities was used. In this evaluation, three plasma heat torches as the primary heat source 20 were focused on a water-cooled copper melting hearth 12. An additional plasma heat torch as a secondary plasma heat source 42 can be focused on a water-cooled copper pouring trough 34, as shown in the drawing. In other evaluations of melting in hearth 12, t' _ g _ fewer than three torches were used. The hearth heating torches, as the primary plasma heat source, were movable in three orthogonal directions; the pouring trough heating torch or secondary plasma heat source was movable in the vertical and one horizontal direction. The sides of the apparatus and the supports for the plasma torches were protected by heat shields. As a result of several trial evaluations, it was found that the combination of a fluid-cooled hearth and a plasma heat source, which may be movable, alone or in combination with a pouring trough as a stream control device, can provide an improved means to melt a metallic material for the purpose of producing a powder metal and without a substantial increase of ceramic impurities which can act as defect sites.
Through -the use of the apparatus of the present invention, there is provided an improved method for making an alloy powder, especially one of a hick temperature alloy or superalloy such as based on Fe, Jo, Nix To or their mixtures, the method being characterized by the substantial avoidance of addition of defect-forming ceramic materials.
This invention has been described in connection with specific embodiments and examples. However, it will be readily recognized by those skilled in the art the various modifications and variations of which the present invention is capable without departing from its scope as represented by the appended claims.
Claims (22)
1. In a method for making a metal powder, the steps of:
disposing in a fluid-cooled hearth having delivery means a metallic material defining an alloy composition;
melting the material in the hearth using a plasma heat source to provide a molten metallic alloy while providing a skull of resolidified material substantially completely between the molten alloy and the hearth and said delivery means; and delivering the molten metallic alloy from the fluid-cooled hearth into a powder metal producer, wherein, in said method, the molten alloy substantially contacts only said skull.
disposing in a fluid-cooled hearth having delivery means a metallic material defining an alloy composition;
melting the material in the hearth using a plasma heat source to provide a molten metallic alloy while providing a skull of resolidified material substantially completely between the molten alloy and the hearth and said delivery means; and delivering the molten metallic alloy from the fluid-cooled hearth into a powder metal producer, wherein, in said method, the molten alloy substantially contacts only said skull.
2. An improved method for making a metal powder comprising the steps of:
providing a hearth having delivery means, said hearth and delivery means having fluid-cooled walls;
disposing in the hearth a metallic material defining an alloy composition;
directing a plasma heat source at the metallic material in the hearth to melt the metallic material;
providing cooling fluid in the walls sufficient to resolidify melted metallic material adjacent to the cooled walls to form a skull of a portion of the metallic material substantially completely on the cooled walls, while maintaining molten alloy in the hearth, and separated therefrom by the skull, as a molten alloy reservoir; and delivering a stream of the molten alloy from the hearth into a powder metal producer, wherein, in said improved method, said molten alloy substantially contacts only said skull.
providing a hearth having delivery means, said hearth and delivery means having fluid-cooled walls;
disposing in the hearth a metallic material defining an alloy composition;
directing a plasma heat source at the metallic material in the hearth to melt the metallic material;
providing cooling fluid in the walls sufficient to resolidify melted metallic material adjacent to the cooled walls to form a skull of a portion of the metallic material substantially completely on the cooled walls, while maintaining molten alloy in the hearth, and separated therefrom by the skull, as a molten alloy reservoir; and delivering a stream of the molten alloy from the hearth into a powder metal producer, wherein, in said improved method, said molten alloy substantially contacts only said skull.
3. The method of claim 2 in which the plasma heat source is swept over a surface of the metallic material to provide substantially uniform heat to the metallic material.
4. The method of claim 2 further including delivering the molten alloy into the powder metal producer through a stream control device, said device having a second delivery means and having a skull formed therein substantially completely between said stream control device and said second delivery means and the molten alloy wherein said molten alloy substantially only contacts said skull.
5. The method of claim 4 wherein:
a pouring trough having fluid-cooled walls is the stream control device.
a pouring trough having fluid-cooled walls is the stream control device.
6. The method of claim 5 including directing a secondary plasma heat source at the molten alloy in the trough.
7. The method of claim 6 including sweeping the secondary plasma heat source over the surface of the molten alloy in the trough to provide substantially uniform heat to the molten alloy.
8. In an apparatus for producing a powder metal alloy from a molten metallic alloy, the improvement comprising:
a fluid-cooled hearth for receiving the metallic alloy said hearth having means for delivering the molten alloy to a powder metal producer, said delivery means also having fluid-cooled walls, which fluid-cooled walls provide a skull of resolidified alloy substantially completely between the molten alloy and said fluid-cooled walls;
a heat source;
means for directing the heat source toward the hearth for melting the metallic alloy and maintaining said metallic alloy molten; and means in said powder metal producer for converting the molten alloy to a powder alloy metal.
a fluid-cooled hearth for receiving the metallic alloy said hearth having means for delivering the molten alloy to a powder metal producer, said delivery means also having fluid-cooled walls, which fluid-cooled walls provide a skull of resolidified alloy substantially completely between the molten alloy and said fluid-cooled walls;
a heat source;
means for directing the heat source toward the hearth for melting the metallic alloy and maintaining said metallic alloy molten; and means in said powder metal producer for converting the molten alloy to a powder alloy metal.
9. The apparatus of claim 8 further comprising means for directing the heat source to sweep the surface of the metallic alloy in the hearth to provide substantially uniform heat to the metallic alloy.
10. The apparatus of claim 8 further comprising a pouring trough disposed to receive molten metallic alloy melted in the hearth and to deliver at least a portion of such molten metallic alloy into the means for converting the molten alloy to a powder metal, said trough having fluid cooled walls, which fluid-cooled walls provide a skull of resolidified alloy substantially completely between the molten alloy andthe fluid-cooled walls.
11. The apparatus of claim 10 further comprising a secondary heat source directed toward the trough to maintain the metallic alloy molten in the trough.
12. The method of claim 2 including delivering the molten alloy into the powder metal producer by tipping the hearth.
13. The method of claim 2 including injecting an atomizing gas into the stream of molten alloy delivered to the powder metal producer to solidify the alloy in powder form.
14. The method of claim 13 including collecting the powder metal alloy.
15. An improved method for making a metal alloy powder comprising the steps of:
providing a hearth having delivery means, said hearth and delivery means having fluid-cooled walls;
disposing in the hearth a metallic material defining an alloy composition;
directing a plasma heat source at the metallic material in the hearth to melt the metallic material;
providing cooling fluid in the walls sufficient to resolidify melted metallic material adjacent to the cooled walls to form a skull of a portion of the metallic material substantially completely within the hearth and the delivery means at the cooled walls, while maintaining molten alloy in the hearth, and separated therefrom by the skull, as a molten alloy reservoir;
delivering the molten alloy from the hearth into a stream control device, said stream control device comprising a pouring trough having a second delivery means, the walls of which trough are fluid-cooled, said trough having a skull formed therein substantially completely between the molten alloy and said fluid-cooled walls;
sweeping a secondary plasma heat source over the surface of the molten alloy in said trough to maintain the alloy molten in the trough;
delivering a stream of molten alloy from the trough to a powder metal producer;
injecting an atomizing gas into the molten alloy stream;
converting the molten alloy to powder alloy; and collecting the powder metal alloy, wherein, in said improved method, said molten alloy substantially contacts only said skull.
providing a hearth having delivery means, said hearth and delivery means having fluid-cooled walls;
disposing in the hearth a metallic material defining an alloy composition;
directing a plasma heat source at the metallic material in the hearth to melt the metallic material;
providing cooling fluid in the walls sufficient to resolidify melted metallic material adjacent to the cooled walls to form a skull of a portion of the metallic material substantially completely within the hearth and the delivery means at the cooled walls, while maintaining molten alloy in the hearth, and separated therefrom by the skull, as a molten alloy reservoir;
delivering the molten alloy from the hearth into a stream control device, said stream control device comprising a pouring trough having a second delivery means, the walls of which trough are fluid-cooled, said trough having a skull formed therein substantially completely between the molten alloy and said fluid-cooled walls;
sweeping a secondary plasma heat source over the surface of the molten alloy in said trough to maintain the alloy molten in the trough;
delivering a stream of molten alloy from the trough to a powder metal producer;
injecting an atomizing gas into the molten alloy stream;
converting the molten alloy to powder alloy; and collecting the powder metal alloy, wherein, in said improved method, said molten alloy substantially contacts only said skull.
16. The apparatus of claim 8 wherein the means for delivering the molten metal alloy from the fluid-cooled hearth to a powder metal producer comprises a means for tipping the hearth.
17. The apparatus of claim 8 wherein the means for converting the molten alloy to a powder metal comprises:
a molten metal inlet;
a source of atomizing gas;
atomizing gas spray means for injecting the atomizing gas into the stream of molten alloy.
a molten metal inlet;
a source of atomizing gas;
atomizing gas spray means for injecting the atomizing gas into the stream of molten alloy.
18. The apparatus of claim 17 wherein the means for converting the molten alloy to a powder metal further comprises;
a cooling tower through which the powder metal passes; and a collector for the powder metal that has passed through the cooling tower.
a cooling tower through which the powder metal passes; and a collector for the powder metal that has passed through the cooling tower.
19. In an apparatus for producing a powder from molten metallic alloy, the improvement comprising;
a hearth for receiving the metallic alloy said hearth including delivery means, said hearth and delivery means having fluid-cooled walls for establishing a skull of solidified alloy between the molten alloy and said walls;
a heat source which is adapted, during operation, to sweep a surface of metallic alloy in the hearth to pro-vise substantially uniform heat to melt the metallic alloy and maintain it in the molten state;
a means for tipping the hearth for delivering molten alloy to a stream control device, said stream control device comprising a pouring trough disposed to receive molten alloy melted in the hearth, said trough having means for pouring a stream of molten alloy from the trough into a powder metal producer, said trough and pouring means having fluid-cooled walls for establishing a skull of solidified alloy between the molten alloy and said walls;
a secondary heat source which is adapted, during operation, to maintain the alloy molten in the trough;
a source of atomizing gas;
an atomizing gas spray means for injecting the atomizing gas into the stream of molten alloy poured from the trough to convert the molten alloy to powder alloy;
a cooling tower through which the powder alloy passes; and a powder collector for collecting the powder alloy that has passed through the cooling tower, wherein, in said apparatus, said molten alloy substantially contacts only said skull.
a hearth for receiving the metallic alloy said hearth including delivery means, said hearth and delivery means having fluid-cooled walls for establishing a skull of solidified alloy between the molten alloy and said walls;
a heat source which is adapted, during operation, to sweep a surface of metallic alloy in the hearth to pro-vise substantially uniform heat to melt the metallic alloy and maintain it in the molten state;
a means for tipping the hearth for delivering molten alloy to a stream control device, said stream control device comprising a pouring trough disposed to receive molten alloy melted in the hearth, said trough having means for pouring a stream of molten alloy from the trough into a powder metal producer, said trough and pouring means having fluid-cooled walls for establishing a skull of solidified alloy between the molten alloy and said walls;
a secondary heat source which is adapted, during operation, to maintain the alloy molten in the trough;
a source of atomizing gas;
an atomizing gas spray means for injecting the atomizing gas into the stream of molten alloy poured from the trough to convert the molten alloy to powder alloy;
a cooling tower through which the powder alloy passes; and a powder collector for collecting the powder alloy that has passed through the cooling tower, wherein, in said apparatus, said molten alloy substantially contacts only said skull.
20. An improved method for making a metal powder from a metallic material defining an alloy composition comprising the steps of melting the metallic material in a fluid-cooled hearth having delivery means and delivering the molten metallic material into a powder metal producer, the improvement comprising:
forming a skull of resolidified metallic material substantially completely between said molten metallic material and said hearth and delivery means;
and contacting said molten metallic material substantially only with said skull.
forming a skull of resolidified metallic material substantially completely between said molten metallic material and said hearth and delivery means;
and contacting said molten metallic material substantially only with said skull.
21. The apparatus of claim 8 wherein said heat source is a plasma heat source.
22. The apparatus of claim 19 wherein said heat source and said secondary heat source are plasma heat sources.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US50725583A | 1983-06-23 | 1983-06-23 | |
| US507,255 | 1983-06-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1233307A true CA1233307A (en) | 1988-03-01 |
Family
ID=24017883
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000456271A Expired CA1233307A (en) | 1983-06-23 | 1984-06-08 | Method and apparatus for making alloy powder |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS6046305A (en) |
| CA (1) | CA1233307A (en) |
| DE (1) | DE3421488A1 (en) |
| FR (1) | FR2548937B1 (en) |
| GB (1) | GB2142046B (en) |
| IT (1) | IT1176287B (en) |
| SE (1) | SE8403301L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104209526A (en) * | 2014-08-26 | 2014-12-17 | 苏州智研新材料科技有限公司 | Preparation method for micro-fine spherical titanium alloy powder |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3737130C2 (en) * | 1987-11-02 | 1996-01-18 | Gerking Lueder Dr Ing | Method and device for producing very fine powder |
| FR2629573B1 (en) * | 1988-04-05 | 1991-01-04 | Aubert & Duval Acieries | CONTINUOUS MELTING HEAD FOR METALS OR ALLOYS |
| US4999051A (en) * | 1989-09-27 | 1991-03-12 | Crucible Materials Corporation | System and method for atomizing a titanium-based material |
| US5084091A (en) * | 1989-11-09 | 1992-01-28 | Crucible Materials Corporation | Method for producing titanium particles |
| GB9000818D0 (en) * | 1990-01-15 | 1990-03-14 | Davy Mckee Sheffield | Tundish |
| US5272718A (en) * | 1990-04-09 | 1993-12-21 | Leybold Aktiengesellschaft | Method and apparatus for forming a stream of molten material |
| DE4011392B4 (en) * | 1990-04-09 | 2004-04-15 | Ald Vacuum Technologies Ag | Process and device for forming a pouring jet |
| DE4102101C2 (en) * | 1991-01-25 | 2003-12-18 | Ald Vacuum Techn Ag | Device for producing powders from metals |
| GB2255572A (en) * | 1991-05-01 | 1992-11-11 | Rolls Royce Plc | An apparatus for gas atomising a liquid |
| US5268018A (en) * | 1991-11-05 | 1993-12-07 | General Electric Company | Controlled process for the production of a spray of atomized metal droplets |
| US5176874A (en) * | 1991-11-05 | 1993-01-05 | General Electric Company | Controlled process for the production of a spray of atomized metal droplets |
| US5198017A (en) * | 1992-02-11 | 1993-03-30 | General Electric Company | Apparatus and process for controlling the flow of a metal stream |
| US8891583B2 (en) | 2000-11-15 | 2014-11-18 | Ati Properties, Inc. | Refining and casting apparatus and method |
| ES2608863T3 (en) | 2007-03-30 | 2017-04-17 | Ati Properties Llc | Melting furnace that includes an ion emitter of ionic plasma by wire discharge |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1921885C3 (en) * | 1968-05-03 | 1976-01-02 | National Distillers And Chemical Corp., New York, N.Y. | Method and device for forming lumpy reaction metal in the form of metal scrap of various shapes and sizes |
| FR2084646A5 (en) * | 1970-03-14 | 1971-12-17 | Leybold Heraeus Verwaltung | |
| FR2098951A5 (en) * | 1970-07-31 | 1972-03-10 | Anvar | Spheroidal granules of refractory material prodn - by two-stage pulverization of molten raw material |
| GB1411076A (en) * | 1971-10-27 | 1975-10-29 | Atomic Energy Authority Uk | Production of particulate material |
| US3829538A (en) * | 1972-10-03 | 1974-08-13 | Special Metals Corp | Control method and apparatus for the production of powder metal |
| JPS6224481B2 (en) * | 1974-12-18 | 1987-05-28 | Intaanashonaru Nitsukeru Co Inc Za | |
| DE2528999C2 (en) * | 1975-06-28 | 1984-08-23 | Leybold-Heraeus GmbH, 5000 Köln | Process and device for the production of high-purity metal powder by means of electron beam heating |
| FR2365633A1 (en) * | 1976-09-24 | 1978-04-21 | Gagneraud Francis | DEVICE ALLOWING REGULAR AND HIGH FLOW TREATMENT OF METALLURGIC MILK AND OTHER GENERAL FUSION MATERIALS |
| JPS54442A (en) * | 1977-06-02 | 1979-01-05 | Mitsubishi Heavy Ind Ltd | Garbage remover |
| DE3211861A1 (en) * | 1982-03-31 | 1983-10-06 | Leybold Heraeus Gmbh & Co Kg | METHOD AND DEVICE FOR PRODUCING HIGH-PURITY CERAMIC-FREE METAL POWDERS |
| DE3235182A1 (en) * | 1982-09-23 | 1984-03-29 | Leybold-Heraeus GmbH, 5000 Köln | Method and device for the production of ceramic-free metal powders |
-
1984
- 1984-05-22 GB GB08413002A patent/GB2142046B/en not_active Expired
- 1984-06-08 IT IT21301/84A patent/IT1176287B/en active
- 1984-06-08 DE DE19843421488 patent/DE3421488A1/en not_active Withdrawn
- 1984-06-08 CA CA000456271A patent/CA1233307A/en not_active Expired
- 1984-06-15 FR FR8409365A patent/FR2548937B1/en not_active Expired
- 1984-06-20 SE SE8403301A patent/SE8403301L/en unknown
- 1984-06-22 JP JP59127674A patent/JPS6046305A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104209526A (en) * | 2014-08-26 | 2014-12-17 | 苏州智研新材料科技有限公司 | Preparation method for micro-fine spherical titanium alloy powder |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8413002D0 (en) | 1984-06-27 |
| IT8421301A0 (en) | 1984-06-08 |
| FR2548937B1 (en) | 1988-04-29 |
| IT8421301A1 (en) | 1985-12-08 |
| GB2142046A (en) | 1985-01-09 |
| IT1176287B (en) | 1987-08-18 |
| GB2142046B (en) | 1987-01-07 |
| JPS6046305A (en) | 1985-03-13 |
| JPH059482B2 (en) | 1993-02-05 |
| DE3421488A1 (en) | 1985-01-03 |
| FR2548937A1 (en) | 1985-01-18 |
| SE8403301L (en) | 1984-12-24 |
| SE8403301D0 (en) | 1984-06-20 |
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