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Publication numberUS3887667 A
Publication typeGrant
Publication date3 Jun 1975
Filing date6 Aug 1973
Priority date15 Jul 1970
Publication numberUS 3887667 A, US 3887667A, US-A-3887667, US3887667 A, US3887667A
InventorsIrvin Dwight Clark
Original AssigneeSpecial Metals Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method for powder metal production
US 3887667 A
Abstract
A method for producing pre-alloyed metallic powder which utilizes a pair of electrodes and a reservoir to accomplish its objectives. An arc is struck between a consumable electrode and a second electrode to produce molten metal which is collected, held and homogenized in a reservoir and subsequently atomized.
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Description  (OCR text may contain errors)

0 United States Patent 11 1 1111 3,887,667 Clark June 3, 1975 [54] METHOD FOR POWDER METAL 2,304,130 12/1942 Truthe 264/8 4 P 2,816,826 12/1957 Byennan 264/12 RODUCTIOI? 3,556,780 1/1971 Holtz, Jr. 264/12 Inventor: Irvm g t Clark, New ord, 3,586,747 6/1971 Radtke et a1. 264/8 [73] Assignee: Special Metals Corporation, New Primary ExaminerR0bert F. White Hartford, Assistant Examiner-J. R. Hall [22] Filed: Aug 6, 1973 Attorney, Agent, or FirmVincent C. Gioia; Robert F.

Dropkm [21] Appl. No.: 386,127

I Related US. Application Data ABSTRACT [63] Continuation of Ser. No. 55,123, July 15, 1970,

abandoned. A method for producing pre-alloyed metallic powder which utilizes a pair of electrodes and a reservoir [52] US. Cl 264/8; 264/10 to a omplish its objectives, An arc is struck between [51] Int. Cl 1322f 9/00 a consumable electrode and a second electrode to Field 0f Search 8 produce molten metal which is collected, held and homogenized in a reservoir and subsequently atomized. [56] References Cited UNITED STATES PATENTS 2/1940 Wissler 264/25 5 Claims, 1 Drawing Figure METHOD FOR PQWDER METAL'PRODUCTION This 'is a continuation of application Ser. No. 55:123. filed July, 15, l970,'n'ow abandoned. I

The present invention relates toa method of producing powder and'more" particularly to a'method of producing pre-alloyedmetallic powder. i

Design applications frequently require alloys which will not fail at elevated temperaturesregt, l,70()F, under relatively high stresses; e.g., l5 ksi.'Alloys which meet the requirements are referred to as superalloys."

An exemplary superalloy consists essentially of, in weight percent, up to 0.18%carbon, from l4.2 to cobalt, froml3.7 to 16% chromium, from 3.8 to 5.5% molybdenum, from 2.7 5 to 3.75% titanium, from3.75 to 4.75% aluminum, up to 4% iron, from 0.005 to 0.035% boron, up to 0.5% zirconium,'balance essentially nickel with incidental impurities. Many'other superalloys are described in'various technical publicatlons.

Superalloys are often desired in,small and/or complex shapes. These shapes are most economically produced by powder metallurgy techniques. To produce optimum mechanical properties in powder metallurgy manufactured products it is often desirable to use pre alloyed powder, i.e., powder that has each element present in each particle in substantially equal amounts.

Metallic powder has been produced from consumable electrodes. Certain prior practices comprised the striking of an are between a metallic consumable spinning electrode and a tungsten electrode and others comprised the striking of an are between a metallic consumable electrode and a spinning wheel. A particular prior art process is disclosed in US. Pat. No. 2,897,539 issued on Aug. 4, 1959. The process disclosed therein is disadvantageous insofar as it requires a starter body to protect the rotating table from damage caused by the arc and to preclude contamination of the powder being produced. In addition, it is plagued by a troublesome sliding electrical contact to the rotating table.

I have determined that the prior art consumable electrode melting processes for producing metallic powder, such as the process disclosed in U.S. Pat. No. 2,897,539, are not suitable for the production of prealloyed Superalloy metallic powder as superalloy consumable electrodes have a segregated; i.e., heterogeneous, makeup. Superalloy consumable electrodes have a concentration of low melting point impurities, elements and compounds in their center and form metal droplets of varying composition when melted. The grains of consumable electrodes grow inward during their solidification and drive the low melting point impurities, elements and compounds along with them. thereby setting up a degree of segregation within the electrodes. This degree of segregation is more prominent in superalloys than in other alloys as superalloys have a greater difference between their liquidus and solidus temperatures and since superalloys are statically cast.

The present invention provides a method for producing pre-alloyed metallic powder and utilizes a pair of consumable electrodes and a reservoir; e.g., a tundish, to accomplish its objectives. Use of a pair of electrodes removes the need for an electrical connection to the rotating table which obviates the troublesome sliding electrical contact and eliminates the requirement of a starter body to protect the rotating table from damage caused by the arc and to preclude contamination of the powder being produced. In addition, the double electrodes improve melting efficiency when both are consumablel'The reservoir provides a means for holding a homogenizing molten metal prior to atomization.

It is accordingly an object of this invention to provide a methodfor producing pre-alloyed metallic powder.

The foregoing and other objects of the invention will be best understood from the following description, reference being had to the accompanying drawing wherein:

The Figure is a schematic view of an embodiment of the apparatus for producing pre-alloyed powder from consumable electrodes.

The method of the present invention comprises the steps of melting a metallic consumable electrode by striking an arc between it and a second electrode (the second electrode can be consumable or nonconsumpassing the homogenized molten metal from the reservoir, atomizing the homogenized molten metal into powder and collecting the powder. Atomization can be performed in the air but is preferably performed in a non-reactive atmosphere such as an inert atmosphere; e.g., argon, or a vacuum. Illustrative methods of atomization comprise the steps of passing the homogenized .molten metal onto a moving disintegrator or into an inert gas stream.

The apparatus used to perform the method of the present invention is best seen from the Figure which is a schematic view of a particular embodiment of the invention. It comprises reservoir or tundish 10, having an inlet 10 and outlet valve 10'', which holds and homogenizes molten metal 20, supplied from consumable electrodes 11 and 12 (either electrode could have been nonconsumable), electrical connections 13 and 14 for striking an are between electrodes 11 and 12, hydraulic pressure cylinders 15 and 16 for moving electrodes 11 and 12 together. sight port 17 for viewing the are between electrodes 11 and 12, resistance heater 18 for supplying heat to molten metal 20 in tundish l0, atomization chamber 30, disintegrating wheel 31 for atomizing the molten metal (an inert gas stream or a vibrating disintegrator could have been used), shaft 33 for imparting motion to disintegrating wheel 31 through motor 35 and speed increaser 37, vacuum pump 39 and inert gas source 41 for producing a nonreactive atmosphere in atomization chamber 30 through conduits 40 and 42, hopper 43 for collecting metallic powder 50, moving belt 45 for carrying metallic powder 50 into hopper 43, shield 47 for directing metallic powder 50 onto belt 45, cooling coils 49 to dissipate heat from powder 50 and atomization chamber 30 so as to keep particles from adhering to each other, container chamber 60, containers 62 for receiving powder from hopper 43 and turntable 64 for holding and placing empty containers below hopper 43.

In operation the relative position of consumable electrodes 11 and 12 is adjusted, through hydraulic pressure cylinders 15 and 16, to obtain proper spacing for the passing of an electrical arc. Current is passed through electrical connections 13 and 14 in order to strike an arc and melt the electrodes. Proper spacing of consumable electrodes 11 and 12 is maintained through hydraulic pressure cylinders and 16 as the electrodes are consumed. The character of the arc is observed through sight port 17. Molten metal from the electrodes is collected through inlet 10 and held in tundish 10 for a period of time sufficient to homogenize it. A nonreactive atmosphere is created in atomization chamber 30 through conventional means utilizing vacuum pump 39 and conduit 40 or vacuum pump 39, conduit 40, inert gas source 41 and conduit 42. Motion is imparted to disintegrating wheel 31 from motor 35 through speed increaser 37 and shaft 33. Molten metal is atomized into metallic powder by being passed from tundish 10, through outlet valve 10-", onto disintegrating wheel 31 (outlet valve 10" is positioned at mid radius with respect to wheel 31 so as to give the powder particles proper directional motion, as depicted in the Figure). Metallic powder is carried to hopper 43 by moving belt 45 and passed through hopper 43 into collecting containers 62.

From the above paragraphs it will be apparent to those skilled in the art that the novel principles of the invention disclosed herein in connection with specific examples thereof will suggest various other modifications and applications of the same. It is accordingly desired that in construing the breadth of the appended I claims they should not be limited to the specific examples described herein.

1 claim:

1. A method of producing metallic powder of a superalloy wherein each element in the alloy is present in each particle of powder in substantially equal amounts,

4 which comprises the steps of: arranging a statically cast superalloy consumable electrode having a heterogeneous make-up in a substantially horizontal position; arranging a second electrode in a substantially horizontal position; melting said consumable electrode by striking an electric are between it and said second elec-.

trode; collecting molten metal droplets from said consumable electrode in a heated reservoir. said droplets having varying compositions; holding said molten metal in said reservoir for a period of time sufficient to homogenize it; passing said homogenized molten metal from said reservoir; atomizing said homogenized molten metal and cooling it to a temperature below its melting point as it passes from said reservoir, thereby forming metallic superalloy powder, each particle of powder containing each element in said alloy in substantially equal amounts; and collecting said powder, said powder being processable into parts having excellent high temperature strength.

2. A method according to claim 1 wherein said atomizing comprises the step of passing said homogenized molten metal onto a moving disintegrator.

3. A method according to claim 1 wherein said atomizing is performed in a nonreactive atmosphere.

4. A method according to claim 1 wherein said second electrode is a metallic consumable electrode.

5. A method according to claim 2 wherein said moving disintegrator is a wheel and wherein said molten metal contacts said wheel off-center thereof.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2189387 *5 Mar 19386 Feb 1940Haynes Stellite CoMethod of making hard compositions
US2304130 *16 Apr 19418 Dec 1942Chemical Marketing Company IncProcess for the conversion of metals into finely divided form
US2816826 *4 Nov 195217 Dec 1957Brennan Joseph BApparatus for and method of producing metal powders and metal strips
US3556780 *3 Jan 196619 Jan 1971Iit Res InstProcess for producing carbide-containing alloy
US3586747 *9 Apr 196922 Jun 1971Int Lead Zinc ResMethod of obtaining strips and sheets of zinc and zinc alloys
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3963812 *30 Jan 197515 Jun 1976Schlienger, Inc.Method and apparatus for making high purity metallic powder
US4027718 *24 Nov 19757 Jun 1977Skf Nova AbProcess for manufacturing a reinforcing material for concrete
US4153655 *23 Jul 19768 May 1979Minnick Leonard JProducts from molten fly ash and scrubber sludge including fly ash
US4256677 *12 Apr 197617 Mar 1981Magnavox Government And Industrial Electronics Co.Apparatus and method for making small spheres
US4259271 *4 May 197931 Mar 1981Minnick L JohnMethod of making shot from molten siliceous-aluminous composition
US4315720 *5 Mar 198016 Feb 1982Itoh Metal Abrasive Co., Ltd.Apparatus for producing spherical particles and fibers with a specially fixed size from melts
US4323523 *27 Aug 19796 Apr 1982Sato Technical Research Laboratory Ltd.Process and apparatus for producing spherical particles and fibers with a specially fixed size from melts
US4374074 *31 Oct 198015 Feb 1983Sato Technical Research Laboratory Ltd.Process for producing fibers with a specially fixed size from melts
US4386896 *18 Feb 19827 Jun 1983Allied CorporationApparatus for making metallic glass powder
US4443390 *24 Mar 198217 Apr 1984U.S. Philips CorporationMethod for making amalgam pellets
US4523621 *17 Mar 198318 Jun 1985Allied CorporationMethod for making metallic glass powder
US4886547 *17 Sep 198712 Dec 1989Nippon Kokan Kabushiki KaishaPowder manufacturing apparatus and method therefor
US5460701 *27 Jul 199324 Oct 1995Nanophase Technologies CorporationMethod of making nanostructured materials
US5874684 *3 May 199623 Feb 1999Nanophase Technologies CorporationNanocrystalline materials
US663530712 Dec 200121 Oct 2003Nanotek Instruments, Inc.Manufacturing method for thin-film solar cells
EP0282604A1 *17 Sep 198721 Sep 1988Nippon Kokan Kabushiki KaishaApparatus for producing powder and process for its production
WO1995003907A1 *26 Jul 19949 Feb 1995Nanophase Tech CorpMethod and apparatus for making nanostructured materials
Classifications
U.S. Classification75/334, 264/10
International ClassificationB01J2/04, B22F9/10
Cooperative ClassificationB22F2999/00, B22F2009/0848, B22F9/10, B01J2/04
European ClassificationB22F9/10, B01J2/04
Legal Events
DateCodeEventDescription
14 May 1993ASAssignment
Owner name: CREDIT LYONNAIS NEW YORK BRANCH, NEW YORK
Free format text: SECURITY INTEREST;ASSIGNOR:SPECIAL METALS CORPORATION;REEL/FRAME:006540/0204
Effective date: 19900831
19 Sep 1990ASAssignment
Owner name: SPECIAL METALS CORPORATION, NEW YORK
Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:HELLER FINANCIAL, INC.;REEL/FRAME:005463/0096
Effective date: 19900831
16 Nov 1987AS17Release by secured party
Owner name: AL-INDUSTRIAL PRODUCTS, INC., A CORP. OF PA
Effective date: 19870827
Owner name: ALLEGHENY INTERNATIONAL, INC., A C
Owner name: SPECIAL METALS CORPORATION, 240 TWO CHATHAM CENTER
16 Nov 1987ASAssignment
Owner name: SPECIAL METALS CORPORATION, 240 TWO CHATHAM CENTER
Free format text: RELEASED BY SECURED PARTY;ASSIGNORS:AL-INDUSTRIAL PRODUCTS, INC., A CORP. OF PA;ALLEGHENY INTERNATIONAL, INC., A CORP. OF PA;REEL/FRAME:004846/0078
Effective date: 19870827
Owner name: SPECIAL METALS CORPORATION,PENNSYLVANIA
Free format text: RELEASED BY SECURED PARTY;ASSIGNORS:AL-INDUSTRIAL PRODUCTS, INC., A CORP. OF PA;ALLEGHENY INTERNATIONAL, INC., A CORP. OF PA;US-ASSIGNMENT DATABASE UPDATED:20100526;REEL/FRAME:4846/78
3 Sep 1987ASAssignment
Owner name: SPECIAL METALS CORPORATION
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31 Aug 1987ASAssignment
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2 Apr 1987ASAssignment
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18 Mar 1985ASAssignment
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29 Dec 1983ASAssignment
Owner name: AL-INDUSTRIAL PRODUCTS, INC. 2700 TWO OLIVER PLAZA
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Owner name: CITICORP INDUSTRIAL CREDIT, INC., BOND COURT BLDG.
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Effective date: 19831223
29 Dec 1983AS06Security interest
Owner name: AL-INDUSTRIAL PRODUCTS, INC. 2700 TWO OLIVER PLAZA
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Effective date: 19831229