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Publication numberUS3652261 A
Publication typeGrant
Publication dateMar 28, 1972
Filing dateJun 25, 1969
Priority dateJun 25, 1969
Also published asDE2030635A1
Publication numberUS 3652261 A, US 3652261A, US-A-3652261, US3652261 A, US3652261A
InventorsTaubenblat Pierre W
Original AssigneeAmerican Metal Climax Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Iron powder infiltrant
US 3652261 A
Abstract
Infiltrant and process for using same for impregnating iron and iron base alloy powder compacts, said infiltrant being an atomized cupreous alloy powder composition containing at least 85 percent by weight of copper and having iron, manganese, aluminum and nickel as essential alloying components thereof. Carbon and lubricant may be incorporated therein as optional ingredients.
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Description  (OCR text may contain errors)

United States Patent Taubenhlat [54] IRON POWDER INFILTRANT [72] Inventor: Pierre W. Taubenblat, Somerset, NJ.

[73] Assignee: American Metal Climax, Inc., New York,

[22] Filed: June 25, 1969 [21] Appl. No.: 836,569

2,430,419 11/1947 Edens ..7s/ 1 s9 1 51 Mar. 28, 1972* Koehring ..29/l82.1 X Michael ..75/ 153 X Primary Examiner-L. Dewayne Rutledge Assistant Examiner-J. Davis Attorney-Kasper T. Serijan [5 7] ABSTRACT lnfiltrant and process for using same for impregnating iron and iron base alloy powder compacts, said infiltrant being an atomized cupreous alloy powder composition containing at least 85 percent by weight of copper and having iron, manganese, aluminum and nickel as essential alloying components thereof. Carbon and lubricant may be incorporated therein as optional ingredients.

10 Claims, No Drawings IRON POWDER INFILTIRANT This invention relates to infiltrants for impregnating metal powder compacts and relates more particularly to new and novel atomized cupreous alloy powder infiltrants which may be advantageously used for impregnating iron and iron base alloy powder compacts.

BACKGROUND OF THE INVENTION Infiltrating iron and iron base alloy powder compacts with other metals and alloys having a melting point lower than that of iron is a well established practice in powder metallurgy, the purpose thereof being to increase the density and strength of the porous iron skeleton. Infiltration is effected either by dipping or fully immersing the porous iron compact in the molten infiltrant or by the more commonly used proce dure of either bringing the unsintered or previously sintered porous iron powder compact into contact with the solid infiltrant as by placing the infiltrant in powder, powder compact, or other suitable form on the surface of the porous iron compact and heating the assembly to a temperature between the melting point of the infiltrant and iron powder compact. In all these procedures, the voids of the porous iron powder compact become substantially filled with the infiltrant metal by the action of the capillary forces thereby enhancing the density and strength of the resulting iron powder skeleton.

In the so-called two step process the iron powder compact is first sintered in the absence of infiltrant and then a sufficient amount of the infiltrant is suitable form is placed thereon. The composite is then heated to a temperature sufficient to melt the infiltrant and impregnate the sintered iron powder compact. The more commonly used so-called one step process, also sometimes referred to as sintration," involves essentially the same procedure except that the iron powder compact is not previously sintered in the absence of the infiltrant. In this process, the green compact with infiltrant on its surface is heated to a temperature sufficient to effect sintering of the iron and also cause the infiltrant to melt and impregnate the iron compact in a single operation.

It is essential that the infiltrant used in either of the aforementioned one or two step processes possess a melting point below the melting point of iron and that it impart to the sintered iron powder compact the prerequisite increase in density and strength sought to be achieved by infiltration. Commercial use considerations make it highly desirable that the infiltrant also (a) not be unduly costly, (b) not occasion heavy erosion, i.e., pitting of the porous iron skeleton surface, (c) not leave excessive infiltrant residue, (d) not result in a strongly adhering residue requiring costly removal treatment, (e) not be overly temperature sensitive so as to become too fluid within the range of furnacing temperature ordinarily used thereby causing infiltrant run-off, (f) not result in undue loss of infiltrant due to vaporation of one or more of its constituents at furnacing temperatures, and (g) not cause the iron powder skeleton to become adhered to its supporting surface in the course of infiltration. Moreover, the infiltrant in compacted form should possess adequate green strength and otherwise lend itself to effective use at the commonly used furnacing temperatures for infiltrating iron powder compacts, said temperature usually ranging between 2,010 to 2,050 F. or thereabouts.

It is a principal object of the present invention to provide new and novel infiltrant compositions which meet the aforementioned requirements for a satisfactory infiltrant for iron and iron base alloy powder compacts. It is another object of this invention to provide an improved process for impregnating iron and iron base alloy powder compacts whereby practically no erosion of the infiltrated skeleton takes place and the resulting infiltrant residue does not adhere to the skeleton surface. Further objects and advantages of the present invention will become apparent from the detailed description hereinafter presented.

THE PRIOR ART Known infiltrants for iron and iron base alloy powder compacts include copper powder and a variety of cupreous alloy powder compositions and powder blends including brass, bronze, copper-iron, copper-iron-manganese, copper-ironmanganese-aluminum, copper-cobalt and copper-cobalt-zinc, among others. While some of the known cupreous alloy powder infiltrant compositions as, for example, those containing cobalt possess the attribute of leaving no residue, such infiltrant powder compositions are relatively costly and result in the production of a somewhat rough skeleton surface. Such infiltrant powders also possess relativelylow green strength and further tend toward excessive fluidity especially at the higher furnacing temperatures. Excessive fluidity of the infiltrant composition during furnacing not only causes infiltrant losses and sticking of the iron powder compact to its support but also usually necessitates more frequent furnace cleaning occasioned by deposition of volatile components on the furnace walls.

Of the known infiltrants of the type that ordinarily leave a residue, cupreous powder infiltrant compositions containing iron and manganese have been rather widely used in commercial practice in recent years. The heretofore used infiltrants of this type, however, have the drawback of causing substantial erosion, i.e., pitting of the surface of the iron or iron base alloy powder skeleton. Further, all such residue leaving infiltrant powder compositions have the detrimental characteristic of leaving a rather strongly adhering residue on the surface of the impregnated skeleton necessitating brushing, grinding or other treatment for its removal. There is a definite need in the industry for improved infiltrant powder compositions which 'can be made available at relatively low cost and which overcome or minimize the problems attributable to skeleton erosion and adhering of the infiltrant residue to the skeleton surface.

SUMMARY OF THE INVENTION The present invention provides atomized powder infiltrant compositions containing at least percent and preferably a minimum of percent by weight of copper, said copper containing iron, manganese, aluminum and nickel, in the amounts hereinafter specified, as essential alloying components. Carbon, preferably as graphite, and lubricant of the type hereinafter specified may be additionally included as optional ingredients, it being preferable to include the same in intimate admixture with the atomized cupreous alloy powder infiltrant. The use of the atomized cupreous alloy powder infiltrant compositions of this invention enables improvements in the process for impregnating iron powder and iron base alloy powder compacts whereby erosion of the infiltrated skeleton is minimized and the infiltrant residue is non-adhering.

TECHNICAL DISCLOSURE OF THE INVENTION Infiltrant alloy powder compositions within the scope of the present invention contain, on a weight basis, 2 to 7 percent iron, 1 to 7 percent manganese, 0.1 to 0.6 percent aluminum, 0.3 to 4 percent nickel and the balance copper and incidental impurities. Preferred infiltrant alloy powder compositions in accordance with the present invention, however, contain from 4 to 6 percent iron, 1.2 to 3 percent manganese, 0.2 to 0.4 percent aluminum, 0.4 to 2 percent nickel, balance copper. A representative infiltrant alloy powder composition contains approximately 5 percent iron, 1.5 percent manganese, 0.3 percent aluminum, 0.6 percent nickel, balance copper. Carbon and lubricant, when included, may be added in amounts ranging from about 0.2 to about 1.5 percent and from about 0.5 to about 1.5 percent by weight, respectively, with the use of about 0.5 percent graphite and about 1 percent lubricant being generally preferred.

For avoiding erosion of the skeleton and adherence of the infiltrant residue to the skeleton, it has been found important,

particularly when infiltrating under furnacing conditions having a dew point exceeding 25 F., that the content of manganese and nickel in the cupreous alloy infiltrant powder be controlled such that a ratio of from 1:1 to 4:1 manganese to nickel is maintained, it being preferred, however, to maintain said ratio between 2:1 and 3:1 and optimally at about 2.511 manganese to nickel.

The atomized cupreous alloy powder infiltrants of this invention may be made using conventional atomization techniques and equipment for the making of metal and/or alloy powders. Water atomization employing an inert or reducing protective atmosphere has been found to produce satisfactory results. The particle size range of the atomized infiltrant alloy powder of from less than 60 mesh to minus 325 mesh (US. Standard Mesh) with about 40 percent being below 325 mesh has been found satisfactory by way of providing desirable flow characteristics to the powder whereby its being processed into green compacts is facilitated.

In making the atomized cupreous alloy powder infiltrant, the desired content of the various alloying ingredients may be added, with stirring, to the molten copper using elemental iron, manganese, aluminum and nickel in powder or any other suitable form. If desired, one or more master alloys such as copper-iron, manganese-nickel, ferro-manganese and the like may also be used in appropriate quantities. The resulting atomized cupreous alloy powder obtained by water atomization, suitably in a nitrogen atmosphere, is then dewatered and dried at about 1,000 E, in a reducing atmosphere. Carbon and lubricant, if included, may be incorporated by blending or otherwise admixing the same in desired amounts with the dried atomized cupreous alloy powder.

As previously indicated, it is not essential that graphite or other carbonaceous material be included in admixture with the infiltrant powder since there are some applications of the infiltrant powder composition of the present invention wherein carbon may be omitted. Similarly, the incorporation of lubricant directly in admixture with the atomized cupreous alloy powder is not essential but its inclusion is preferable not only for reducing friction of die walls during subsequent compaction of the infiltrant powder but also for enhancing the green strength of the infiltrant compacts. Various lubricants of the type commonly used for die lubricating purposes may be used as, for example, zinc stearate, lithium stearate, stearic acid, among others, may be used, it being preferred, however, to use a finely divided powder type lubricant such as ethylenediamine-bis-stearamide (sold by the manufacturer, Nopco Chemical Company under the trademark NOP- COWAX 22 DS).

The atomized cupreous alloy powder compositions so prepared have a melting point generally between l,980 to 2,000 F. or thereabouts and may be used in powder form for some infiltrating applications. For making green compacts in which form infiltrants are more commonly used, the atomized and dried cupreous alloy powder is compacted into round, rectangular or other shape of desired size using conventional powder metallurgy compaction equipment and techniques. The resulting green compact is then ready for use in impregnating porous iron powder compacts using either the aforementioned sintration or two step processes, the infiltration being effected by furnacing at temperatures generally between 2,010 and 2,050 F. or thereabouts using a reducing atmosphere consisting, for example, of hydrogen, carbon monoxide, dissociated ammonia, endothermic gas, exothermic gas or the like, including mixtures thereof. Infiltration tests using the infiltrant compositions of the present invention gave no visible signs of skeleton erosion and, in each instance, the infiltrant residue left on the skeleton was non-adhering and readily removable, i.e., simply fell off.

DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention comprises an atomized cupreous alloy powder infiltrant composition containing 5 percent iron, 1.5 percent manganese, 0.3 percent aluminum, 0.6 percent nickel and the balance copper with its incidental impurities, said atomized cupreous alloy powder being made by water atomization at 2,700-2,800 F. using an inert atmosphere of nitrogen followed by dewatering and drying at about 1,000 F. in a hydrogen or other reducing atmosphere. The resulting atomized powder of particle size ranging from less than 60 to below 325 mesh with about 65 percent thereof being 200 mesh and about 40 percent being below 325 mesh had an apparent density of 3.4 grams per cubic centimeter. Graphite and ethylenediamine-bis-stearamide lubricant were incorporated by blending 0.5 and 1 percent by weight, respectively, with the atomized and dried cupreous alloy powder. Compacts made using a compaction pressure of 30 t.s.i. possessed green density values in excess of 7 grams per cubic centimeter and green strength values of at least 1,000 p.s.i.

Infiltration tests with iron powder compacts containing l percent by weight of carbon and compacted to a density of 6.1 grams per cubic centimeter into the form of standard transverse rupture bars weighing 15.7 grams were conducted utilizing 20 and 25 percent by weight of similarly shaped compacted infiltrant. One step infiltration was used with furnace temperatures being varied from 2010 to 2050 F. and infiltration time from 5 to 20 minutes. Different furnace atmospheres including hydrogen, endothermic gas, exothermic gas and dissociated ammonia were separately used in the infiltration tests with the dew point being maintained at 25-30 F. in accordance with usual infiltration practice. Infiltration results using higher dew points up to 60 F. also proved entirely satisfactory.

In each of the tests, the infiltrant effectively penetrated the iron powder compact without causing any visible erosion of the skeleton. The infiltrant residue amounting to 10 to 15 percent of the amount of infiltrant used fell off easily with no brushing or other type of cleaning being required. Typically, the density of the skeletons was increased to about 7.3 to 7.4 grams per cubic centimeter after impregnation, the transverse rupture strength thereof was approximately 160,000 p.s.i. and a hardness of about (Rockwell B) was obtained.

Examples of other infiltrant compositions within the scope of this invention are listed in Table I wherein the amounts of the various alloying ingredients contained in the cupreous alloy infiltrant are shown, the balance being copper. lnfiltrant compacts made in accordance with the same procedure as used in respect of the previously described preferred embodiment and similarly containing 0.5 and 1 percent by weight of graphite and lubricant possessed green strength values therein shown. Standard transverse rupture bars (M.P.I.F.) made as previously described and impregnated using 25 percent by weight of similarly shaped compacted infiltrant using one step infiltration, a furnacing temperature between 2,010 and 2,020 F., endothermic gas furnace atmosphere with the dew point maintained between 25 and 30 F and furnacing time of 20 minutes and tested in accordance with standard M.P.I.F. procedures yielded the transverse rupture strength values shown in the table.

TABLE I Infiltrant composition (wt. percent) Transverse rupture Infiltrant green strength (p.s.i.) of

Fe Mn N1 A1 strength (p.s.i.) infiltrated skeleton 1. An infiltrant for iron and iron-base alloy powder compacts capable, when melted in contact therewith at furnacing temperatures generally between 2,010 and 2,050 F., of infiltrating the compact without eroding the surface of said compact and leaving a non-adherent residue thereon, said infiltrant consisting essentially of an atomized cupreous alloy powder containing, on a weight basis, from 2 to 7 percent iron, 1 to 7 percent manganese, 0.1 to 0.6 percent aluminum, 0.3 to 4 percent nickel, balance copper and incidental impurities, the copper content being at least 85 percent.

2. The infiltrant composition as defined in claim 1 wherein carbon and lubricant are included as additional ingredients thereof.

3. The infiltrant composition as defined in claim 2 wherein the carbon is in the form of graphite, and the content of graphite and lubricant is from 0.2 to 1.5 percent and from 0.5 to l .5 percent by weight, respectively.

4. The infiltrant composition as defined in claim 1 wherein the ratio of manganese to nickel is maintained between 1:] and 4:1.

5. An infiltrant for impregnating iron and iron base alloy powder compacts, said infiltrant comprising an atomized cupreous alloy powder having a minimal copper content of 90 percent by weight, and containing on a weight basis from 4 to 6 percent iron, 1.2 to 3 percent manganese, 0.2 to 0.4 percent aluminum and 0.4 to 2 percent nickel as essential alloying components thereof, the manganese and nickel being within the ratio from 2:1 to 3:1 manganese to nickel.

6. The infiltrant defined in claim 5 wherein carbon and lubricant are included as additional ingredients in intimate ad mixture therewith.

7. The infiltrant as defined in claim 6 wherein carbon is in the form of graphite and the lubricant is ethylenediamine-bis stearamide the amounts thereof being about 0.5 and about 1 percent by weight, respectively.

8. An infiltrant for iron and iron base alloy powder compacts comprising an atomized cupreous alloy powder, said alloy powder, on a weight basis, consisting essentially of about 5 percent iron, about 1.5 percent manganese, about 0.3 percent aluminum, about 0.6 percent nickel and the balance copper and incidental impurities.

9. The infiltrant as defined in claim 8 wherein about 0.5 percent by weight of graphite and about 1 percent by weight of lubricant are contained therein as additional ingredients.

10. The infiltrant as defined in claim 9 wherein the cupreous alloy powder in admixture with graphite and lubricant is in the form of green compacts.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2430419 *Feb 2, 1945Nov 4, 1947Edens Walter WWelding rod
US2606831 *Apr 18, 1950Aug 12, 1952Gen Motors CorpMethod of impregnation
US3307924 *Jun 30, 1965Mar 7, 1967Glidden CoCopper infiltrating composition for porous ferruginous material
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3889349 *Jun 8, 1973Jun 17, 1975Ford Motor CoBrazing metal alloys
US3994734 *Apr 22, 1974Nov 30, 1976Scm CorporationHigh density infiltrating paste
US4158719 *Jun 9, 1977Jun 19, 1979Carpenter Technology CorporationAlloying controlled to obtain desired qualities
US4168162 *Sep 22, 1978Sep 18, 1979Scm CorporationInfiltrating powder composition
US4286987 *Nov 28, 1979Sep 1, 1981United States Bronze Powders, Inc.Composition for iron powder compact infiltrant
US4491558 *Nov 5, 1981Jan 1, 1985Minnesota Mining And Manufacturing CompanyDies, multilayer
US5096661 *Apr 2, 1991Mar 17, 1992Raybestos Products CompanyVapor infiltration, alloying
US5476534 *Aug 2, 1993Dec 19, 1995Kawasaki Steel CorporationIron-based powder mixture and method
US5553767 *Aug 17, 1994Sep 10, 1996Donald FegleyDurable, pitting resistant and thermoconductive
US5579533 *Aug 17, 1995Nov 26, 1996Donald FegleyMethod of making a soldering iron tip from a copper/iron alloy composite
US5643679 *Dec 14, 1992Jul 1, 1997Kabushiki Kaisha ToshibaDecorative article
US5654106 *Sep 21, 1993Aug 5, 1997Brico Engineering LimitedSintered articles
US6534191 *Jan 26, 2001Mar 18, 2003Suzuki Motor CorporationSintered alloy and method for the hardening treatment thereof
US6719948May 21, 2001Apr 13, 2004Massachusetts Institute Of TechnologyTechniques for infiltration of a powder metal skeleton by a similar alloy with melting point depressed
US7060222May 21, 2001Jun 13, 2006Massachusetts Institute Of TechnologyThe infiltrant fills the powder skeleton, then as the melting point depressant diffuses into the base powder, the liquid undergoes solidification and the material will homogenize; control of dimensions in parts with homogenous microstructure
US7250134Nov 26, 2003Jul 31, 2007Massachusetts Institute Of TechnologyInfiltrating a powder metal skeleton by a similar alloy with depressed melting point exploiting a persistent liquid phase at equilibrium, suitable for fabricating steel parts
US7553445 *Sep 9, 2004Jun 30, 2009Hitachi Powdered Metals Co., Ltd.Forming a mixed powder of copper or copper alloy and iron powder of specified surface area and particle size into a green compact, and sintering to obtain a porous alloy
WO1996005014A1 *Aug 16, 1995Feb 22, 1996Fegley DonaldSoldering iron tip made from a copper/iron alloy composite
WO2002094484A1 *May 17, 2002Nov 28, 2002Massachusetts Inst TechnologyTechniques for infiltration of a powder metal skeleton by a similar alloy with melting point depressed
Classifications
U.S. Classification75/252, 75/337, 420/486, 428/567, 419/27, 75/255, 419/44
International ClassificationC22C9/06, C22C33/02
Cooperative ClassificationC22C9/06, C22C33/0242
European ClassificationC22C33/02C, C22C9/06
Legal Events
DateCodeEventDescription
Apr 7, 1986ASAssignment
Owner name: ALCAN ALUMINUM CORPORATION
Free format text: MERGER;ASSIGNORS:ALCAN ALUMINUM CORPORATION A CORP. OF NY (MERGED INTO);ALCAN PROPERTIES, INC., A CORP OF OHIO (CHANGED TO);REEL/FRAME:004536/0724
Effective date: 19860220
Mar 29, 1982ASAssignment
Owner name: ALCAN ALUMINUM CORPORATION, 100 ERIEVIEW PLAZA, CL
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:AMAX, INC.;REEL/FRAME:003960/0859
Effective date: 19820309
Mar 29, 1982AS02Assignment of assignor's interest
Owner name: ALCAN ALUMINUM CORPORATION, 100 ERIEVIEW PLAZA, CL
Effective date: 19820309
Owner name: AMAX, INC.