US2319240A - Electric contact and the like - Google Patents

Electric contact and the like Download PDF

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Publication number
US2319240A
US2319240A US324742A US32474240A US2319240A US 2319240 A US2319240 A US 2319240A US 324742 A US324742 A US 324742A US 32474240 A US32474240 A US 32474240A US 2319240 A US2319240 A US 2319240A
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United States
Prior art keywords
graphite
contact
silver
disc
plus
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 - Lifetime
Application number
US324742A
Inventor
Earl I Larsen
Earl F Swazy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Duracell Inc USA
Original Assignee
PR Mallory and Co Inc
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Publication date
Application filed by PR Mallory and Co Inc filed Critical PR Mallory and Co Inc
Priority to US324742A priority Critical patent/US2319240A/en
Application granted granted Critical
Publication of US2319240A publication Critical patent/US2319240A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00Contacts
    • H01H1/02Contacts characterised by the material thereof
    • H01H1/021Composite material
    • H01H1/023Composite material having a noble metal as the basic material
    • H01H1/0231Composite material having a noble metal as the basic material provided with a solder layer
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00Contacts
    • H01H1/02Contacts characterised by the material thereof
    • H01H1/021Composite material
    • H01H1/027Composite material containing carbon particles or fibres
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S384/00Bearings
    • Y10S384/90Cooling or heating
    • Y10S384/902Porous member
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00Stock material or miscellaneous articles
    • Y10S428/922Static electricity metal bleed-off metallic stock
    • Y10S428/9265Special properties
    • Y10S428/929Electrical contact feature
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S76/00Metal tools and implements, making
    • Y10S76/11Tungsten and tungsten carbide
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/49002Electrical device making
    • Y10T29/49117Conductor or circuit manufacturing
    • Y10T29/49204Contact or terminal manufacturing
    • Y10T29/49206Contact or terminal manufacturing by powder metallurgy
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/4981Utilizing transitory attached element or associated separate material
    • Y10T29/49812Temporary protective coating, impregnation, or cast layer
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/12All metal or with adjacent metals
    • Y10T428/12486Laterally noncoextensive components [e.g., embedded, etc.]

Description

y 1943 E. l. LARSEN EI'AL 2,319,240
ELECTRIC CONTACT AND THE LIKE Filed March 19, 1940 INVEII TORS Ear! Z la men avid/"IF Jzmzq ATTO R N EY May W, 1943 ELECTRIC CONTACT AND THE LIKE Earl l. llarsen and Earl F. Swazy, Indianapolis,
Ind., assignors to P. B. Mallory & 00., Inc., Indianapolis, Ind., a corporation of Delaware Application March 19, 1940, Serial No. 324,742
2 Claims. '(Ol. 75-22) This invention relates to facing elements such as electric contacts and the manufacture thereof.
An object of the invention is to improve such elements and the methods of manufacture thereof.
Other objects of the invention will be apparent from the following description taken in connection with the appended claims.
The present invention comprises a combination of elements, methods of manufacture and the product hereinafter set forth, the scope of the invention being indicated in the appended claims.
While a preferred embodiment of the invention is described herein, it is contemplated that considerable variation may be made in the method of procedure and the combination of elements, without departing from the spirit of the invention.
In the drawing:
Figure 1 illustrates a contact disc during a preliminary stage of its manufacture;
Figure 2 is a cross section of the contact disc illustrated in Figure 1;
Figure 3 illustrates the furnacing or sintering of the contacts;
Figure d is a cross section of a contact after furnacing;
Figure 5 is a cross section of the contact after a subsequent pressing operation;
Figure 6 is a perspective View of the repressed contact; and
Figure 7 illustrates a contact during a preliminary step in its processing according to a modified procedure.
The present invention relates to improvements in face plates or surfacing elements, particularly of the type formed of mixtures of metals and carbon or graphite particles, or other carbonaceous material. In its preferred embodiment the invention contemplates electric contact plates, or discs, formed of a mixture of powdered contact metal and graphite, pressed into suitable form and sintered.
A feature of the invention resides in the improved structure and composition of the face plate or contact disc wherein carbon or graphite is present in the metal composition at one face and substantially absent at the other face of the plate. Another aspect of the invention resides in the improved method of manufacture wherein the plate or disc is first formed with graphite present throughout and the graphite is subsequently removed from one surface by a degraphitizing process.
The metal used will depend upon the application intended. It is apparent that any metal which is not substantially deleteriously affected by the process will be suitable. For contact purposes a metal having desirable characteristics for contacts is preferred, such as silver, copper, nickel, cadmium, tungsten and molybdenum or alloys or mixtures containing one or more of these elements. The metal or alloy is preferably mixed, in powder form, with the graphite or other carbonaceous material. The preferred composition for contact purposes is a pressed and sintered mixture of silver and graphite powders.
One of the principal objections, heretofore, to
a contact composed of silver and graphite is the fact that it is extremely difficult to attach a backing member thereto. It can not be riveted, staked, screwed or otherwise mechanically attached to the backing material in an efilcient manner. Therefore, it is necessary that the silver graphite pressed material be soldered or brazed to the supporting or current carrying backing. It has been found that when the usual solders are used to perform this brazing operation, that a very weak joint or bond between the silver graphite material and the backing, is obtained. This appears to be due to the fact that when the silver graphite material is heated, the graphite is not tinned or wetted by the soldering. Furthermore, it appears to be very gassy and does not allow the silver to tin or solder properly. This objection or deficiency is entirely overcome when contacts of, for example, silver and graphite, are manufactured according to the present invention.
Following is a description of a, preferred method of preparing silver graphite contacts according to the invention, referencebeing made to the accompanying drawing:
A powder mixture comprising approximately by weight of silver powder and 5% graphite powder is prepared by mixing the powder thoroughly. The mixed powders are then pressed into the desired shape, for example, the contact disc ill illustrated in Figure 1 of the drawing.
The pieces are then laid on a graphite slab H- with one face directly in contact with the graphite slab. The graphite slab ll carrying the contacts Ill is then placed in a heated chamber such as electric furnace l 2 of Figure 3, the chamber having an oxidizing atmosphere.
The cross section of the pressed contact discs, prior to sintering, may appear somewhat as illustrated in Figure 2 of the drawing wherein the graphite particles l3 are interspersed with the silver ll in which there may also be present at this time a few voids IS.
The contact discs are allowed to remain in the heated chamber for a time suiiicient to sinter the silver particles together and to degraphitize the exposed surfaces of the contacts. With a furnace temperature of 900 degrees C. a period of hour is generally satisfactory.
The degraphitizing, which comprises an important aspect of the present invention, is believed to take place in the following manner: The oxidizing atmosphere, for example air, reacts with the graphite particles at and adjacent to the exposed surface of the contacts to form gaseous carbon monoxide or carbon dioxide or both, thereby denuding the pressed mixture of graphite adjacent to the surface. However, the opposite face of the contact which is resting against the graphite slab is protected from oxidation by the graphite slab and hence the graphite particles remain substantially undiminished in quantity at the latter surface.
While air is a satisfactory oxidizing atmosphere, other oxidizing atmospheres may be used such as pure oxygen or even hydrogen, containing a small percentage of oxygen or water vapor. The water vapor reacts with the graphite to form carbon monoxide with the release of pure hydrogen.
Upon removal from the furnace the contact disc may have a cross section such as illustrated in Figure 4. It will be noted that the graphite particles ii are removed from the surface I6 and for a substantial depth below the surface, while the surface I! which was in contact with the graphite slab still contains graphite in substantially undiminished quantity. It will also be noted that the contact disc l has shrunk somewhat in thickness. In order to increase the density of the contact disc and substantially eliminate the voids it is generally preferred, although not essential, to apply a subsequent repressing or coining operation which further reduces the thickness of the contact disc and substantially eliminates the voids. A cross section of the repressed contact disc III is illustrated in Figure and a perspective view thereof in Figure 6.
The depth of the degraphitized layer of the contact will depend upon the temperature at which the sintering operation is carried out and the length of time the piece is held at that temperature. Hence if a degraphitized layer of greater thickness is desired the time of sintering will be correspondingly extended.
Figure 7 illustrates another method of producing a contact of the type described. According to this method the surface of the pressed powder disc 20, similar to disc l0 previously described, at which it is desired to retain the graphite, is painted or otherwise coated with a protective layer 2| such as a paint formed from refractory material with a suitable binder. The refractory paint protects one face of the disc from the oxidlzing atmosphere allowing the other surface of the disc to be degraphitized. The refractory material may subsequently be removed.
While the invention has been described in its preferred form as applied to silver graphite contact compositions, the invention also contemplates other compositions for contact purposes and other uses. For example, a mixture of copper powder with various amounts of graphite may be used; likewise a mixture of copper, silver and graphite powders is suitable. Other powder mixtures which are suitable, particularly for contact purposes, are silver plus tungsten plus graphite, silver plus molybdenum plus graphite, copper plus tungsten plus graphite, silver plus nickel plus graphite, silver plus nickel plus cadmium plus graphite. Any of these metals may likewise be used with other forms of carbon instead of graphite as well as certain carbonaceous compounds, particularly the type which decompose leaving a residual carbon deposit upon sinterlng. It will also be understood that while a composition of silver and 5% graphite is mentioned by way of illustration various other proportions of the materials may likewise be used.
Although the invention has been described as applied to electric contacts it is also contemplated that other types of face plates or surfacing elements, such as bearings, clutch facings and the like come within the purview of the invention.
While the present invention, as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby but it is intended to cover the invention broadly within the spirit and scope of the appended claims.
What is claimed is:
1. The method of making electric contacts which comprises mixing graphite and contact metal powders, pressing the mixture into a body of suitable shape, coating the contact face of said body with a protective layer of refractory paint and then sintering said body in an oxidizing atmosphere, whereby to produce a sintered contact body having graphite at and adjacent the contact face thereof and substantially devoid of graphite at the back face thereof.
2. The method of making a weldable silvergraphite electric contact element, comprising coating 9. surface of said element with a refractory paint and then oxidizing the graphite from the exposed surfaces of said element to thereby leave a readily weldable silver face substantially free of graphite.
EARL I. LARSEN. EARL F. SWAZY.
US324742A 1940-03-19 1940-03-19 Electric contact and the like Expired - Lifetime US2319240A (en)

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US324742A US2319240A (en) 1940-03-19 1940-03-19 Electric contact and the like
GB1384940A GB539996A (en) 1940-03-19 1940-09-04 Improvements in and relating to facing elements or electrical contact plates

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Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2436205A (en) * 1946-12-20 1948-02-17 Gen Electric Resistance welding electrode
US2450339A (en) * 1943-09-17 1948-09-28 Mallory & Co Inc P R Method of making porous metal filters
US2464517A (en) * 1943-05-13 1949-03-15 Callite Tungsten Corp Method of making porous metallic bodies
US2621123A (en) * 1949-04-23 1952-12-09 Gibson Electric Company Method of sintering silver contact material
US2634342A (en) * 1950-02-18 1953-04-07 Raymond Rosen Engineering Prod Commutator
US2652621A (en) * 1949-02-25 1953-09-22 Gen Electric Method of making a unitary thermionic filament structure
US2652624A (en) * 1948-08-28 1953-09-22 Wilson H A Co Method of producing composite metal
US2723444A (en) * 1951-05-16 1955-11-15 Gibson Electric Company Contacts
US2733968A (en) * 1956-02-07 Wear resistant bushing or liner for the plunger
US2786104A (en) * 1952-11-04 1957-03-19 Muirhead & Co Ltd Rotary stud switches
US2790100A (en) * 1951-06-06 1957-04-23 James V Caputo Electrical brush
US2799081A (en) * 1952-09-24 1957-07-16 Gibson Electric Company Electrical contacts
US2876097A (en) * 1957-03-28 1959-03-03 Purolator Products Inc Aluminum filters and method of production
US2984894A (en) * 1956-11-30 1961-05-23 Engelhard Ind Inc Composite material
US3086285A (en) * 1957-11-05 1963-04-23 Engelhard Ind Inc Electrical contacts
US3428374A (en) * 1966-04-13 1969-02-18 Kaman Corp Self-lubricating bearing
US3601645A (en) * 1968-05-23 1971-08-24 Morganite Carbon Ltd Electrical contact brushes
FR2181699A1 (en) * 1972-04-28 1973-12-07 Siemens Ag
US4084669A (en) * 1975-08-25 1978-04-18 Hitachi, Ltd. Composite collector
DE3108502A1 (en) * 1979-11-28 1982-09-30 Kostal Fa Leopold Electrical contact-making device and a method which is suitable for producing the same
US4457780A (en) * 1981-04-10 1984-07-03 Sumitomo Electric Industries, Ltd. Electric contact materials
US5141702A (en) * 1990-03-13 1992-08-25 Olin Corporation Method of making coated electrical connectors
DE19503184C1 (en) * 1995-02-01 1996-05-02 Degussa Ag-based material for electrical contacts with improved erosion characteristics and resistant to welding
US20040174088A1 (en) * 2003-02-04 2004-09-09 Kyoji Inukai Multilayer brush

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8808323D0 (en) * 1988-04-08 1988-05-11 T & N Technology Ltd Improvements in/relating to coating of metal substrates

Cited By (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2733968A (en) * 1956-02-07 Wear resistant bushing or liner for the plunger
US2464517A (en) * 1943-05-13 1949-03-15 Callite Tungsten Corp Method of making porous metallic bodies
US2450339A (en) * 1943-09-17 1948-09-28 Mallory & Co Inc P R Method of making porous metal filters
US2436205A (en) * 1946-12-20 1948-02-17 Gen Electric Resistance welding electrode
US2652624A (en) * 1948-08-28 1953-09-22 Wilson H A Co Method of producing composite metal
US2652621A (en) * 1949-02-25 1953-09-22 Gen Electric Method of making a unitary thermionic filament structure
US2621123A (en) * 1949-04-23 1952-12-09 Gibson Electric Company Method of sintering silver contact material
US2634342A (en) * 1950-02-18 1953-04-07 Raymond Rosen Engineering Prod Commutator
US2723444A (en) * 1951-05-16 1955-11-15 Gibson Electric Company Contacts
US2790100A (en) * 1951-06-06 1957-04-23 James V Caputo Electrical brush
US2799081A (en) * 1952-09-24 1957-07-16 Gibson Electric Company Electrical contacts
US2786104A (en) * 1952-11-04 1957-03-19 Muirhead & Co Ltd Rotary stud switches
US2984894A (en) * 1956-11-30 1961-05-23 Engelhard Ind Inc Composite material
US2876097A (en) * 1957-03-28 1959-03-03 Purolator Products Inc Aluminum filters and method of production
US3086285A (en) * 1957-11-05 1963-04-23 Engelhard Ind Inc Electrical contacts
US3428374A (en) * 1966-04-13 1969-02-18 Kaman Corp Self-lubricating bearing
US3601645A (en) * 1968-05-23 1971-08-24 Morganite Carbon Ltd Electrical contact brushes
FR2181699A1 (en) * 1972-04-28 1973-12-07 Siemens Ag
US4084669A (en) * 1975-08-25 1978-04-18 Hitachi, Ltd. Composite collector
DE3108502A1 (en) * 1979-11-28 1982-09-30 Kostal Fa Leopold Electrical contact-making device and a method which is suitable for producing the same
US4457780A (en) * 1981-04-10 1984-07-03 Sumitomo Electric Industries, Ltd. Electric contact materials
US5141702A (en) * 1990-03-13 1992-08-25 Olin Corporation Method of making coated electrical connectors
DE19503184C1 (en) * 1995-02-01 1996-05-02 Degussa Ag-based material for electrical contacts with improved erosion characteristics and resistant to welding
US20040174088A1 (en) * 2003-02-04 2004-09-09 Kyoji Inukai Multilayer brush
US6815862B2 (en) * 2003-02-04 2004-11-09 Denso Corporation Multilayer brush

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Publication number Publication date
GB539996A (en) 1941-10-01

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