US3132022A - Metal whiskers having an essentially constant diameter of not more than 1000 angstroms - Google Patents

Metal whiskers having an essentially constant diameter of not more than 1000 angstroms Download PDF

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Publication number
US3132022A
US3132022A US120648A US12064861A US3132022A US 3132022 A US3132022 A US 3132022A US 120648 A US120648 A US 120648A US 12064861 A US12064861 A US 12064861A US 3132022 A US3132022 A US 3132022A
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United States
Prior art keywords
whiskers
particles
constant diameter
essentially constant
angstroms
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Expired - Lifetime
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US120648A
Inventor
Fred E Luborsky
Charles R Morelock
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General Electric Co
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General Electric Co
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Publication date
Application filed by General Electric Co filed Critical General Electric Co
Priority to US120648A priority Critical patent/US3132022A/en
Priority to GB20503/62A priority patent/GB981172A/en
Priority to DE19621464614 priority patent/DE1464614B1/en
Priority to BE618632A priority patent/BE618632A/en
Priority to DK273962AA priority patent/DK116143B/en
Priority to CH763162A priority patent/CH409165A/en
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Publication of US3132022A publication Critical patent/US3132022A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • Y—GENERAL 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
    • Y10S264/19—Inorganic fiber
    • Y—GENERAL 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S75/00—Specialized metallurgical processes, compositions for use therein, consolidated metal powder compositions, and loose metal particulate mixtures
    • Y10S75/952—Producing fibers, filaments, or whiskers
    • Y—GENERAL 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12431—Foil or filament smaller than 6 mils

Definitions

  • This invention relates to magnets and more particularly to permanent magnets constructed of nearly perfect single crystal whiskers.
  • Another object of this invention is to provide an improved magnet composed of a plurality of ferromagnetic whiskers.
  • FIG. 1 is a graph showing the intrinsic coercive force of various types of small ferromagnetic particles as a function of the diameters of the particles.
  • FIG. 2 is a greatly enlarged view showing the ferromagnetic whiskers of this invention.
  • the elongated ferromagnetic whiskers of this invention may be composed of iron, nickel, cobalt and alloys of these three metals.
  • Probably the most important single characteristic which the whiskers must have to obtain higher coercive forces than heretofore is an essentially constant diameter throughout the entire length of each whisker.
  • the whiskers are elongated, smooth and of substantially constant diameter throughout their entire lengths. Magnets can be produced from the whiskers by assembling a plurality of them together into one integral magnet body by conventional techniques. I
  • the intrinsic coercive force of the whiskers of this invention is compared to the intrinsic coercive forces of the best small particles currently available.
  • Curve illustrates the intrinsic coercive force, in oersteds, of generally spherically-shaped iron particles produced by electrodeposition into mercury.
  • Curve 11 indicates similar properties for elongated magnetic particles also produced by deposition into mercury.
  • a comparison of the values obtained from the two types of particles clearly indicates that the elongated configuration is much more effective in delivering high coercive forces than is the generally spherical geometry.
  • the coercive forces shown by curve 11 for the mercury-deposited, elongated particles were obtained from specimens having the particles aligned with the long axis parallel to the direction of magnetic measurement, although substantially the same coercive forces are obtained from randomly distributed particles.
  • Curve 12 of the drawings indicates the intrinsic coercive forces of iron whiskers produced according to the present invention.
  • the valves indicated by curve 12 were ob tained from specimens composed of elongated iron 3,132,022 Patented M-ay'5, 1964 ice whiskers whose long axes were randomly distributed with "respectto the direction of magnetic measurement. Additional measurements were made on specimens composed of elongated whiskers whose long axes were aligned generally parallel to the directionof magnetic measurement and it-was found that the coercive forces were substantially the same as the non-aligned Whiskers when the whisker diameters were on the order of about 500 A.
  • the coercive force of an aligned whisker specimen was about 37.5 percent less than that of the non-aligned specimen.
  • Theory indicates that the coercive force of aligned whiskers should become larger than the coercive force of randomly distributed whiskers when the diameter becomes'less than a critical diameter.
  • the theoretical critical diameter is felt to be about 250 A., but test data indicates that the actual critical diameter is somewhat larger, for example between 400 and 500 A.
  • whisker having a diameter of about 250 A. has an intrinsic coercive force of about 3000 oerstedsa-t room temperature, this value being appreciably higher than has previously been obtainable in other small particles.
  • the general shape of the whiskers is indicated. It will be noted that they are elongated, and substantially uniform in diameter throughout the entire length thereof. It is the small diameter and the uniformity of this diameter which makes it possible for the present whiskers to attain their high magnetic properties.
  • the whiskers of this invention may be produced by placing a source metal body and a substrate body in a closed chamber which is continuously evacuated. The chamber is then heated by any suitable means to a temperature such that the source metal body begins to evaporate. The vapor then resulting will be deposited upon the substrate body, which is maintained at a temperature sufficiently below that of the source metal body to provide for deposition and growth of whiskers from its surface.
  • a complete description of the method for producing whiskers can be found in the copending application of Charles R. Morelock Serial No. 120,560, now abandoned, filed concurrently herewith and assigned to the same assignee as the present invention.
  • Magnets can be produced using the present whiskers by agglomerating a plurality of the whiskers in a suitable matrix material.
  • a metal such as lead or a plastic matrix, may be used to combine the whiskers. Measurements were made of a magnet produced by combining a plurality of whiskers on an insulating plastic film and it was found to have coercive forces superior to mag nets previously produced. from existing small ferromagnetic particles.

Description

ay 5, 1964 F. E. LUBORSKY ETAL 3,132,022
METAL WHISKERS HAVING AN ESSENTIALLY CONSTANT DIAMETER 0F NOT MORE THAN 1000 ANGSTROMS Filed June 29, 1961 mpoa w Qm mu m smu 2.53
1&0 1,0'00
Diameter, Angst/ems s m .s m w Fig. 2
lnvenfars Fred E. Lubors/ry; Char/es R More/00k by M j The/r Afforne y 3,132,022 METAL WHISKERS HAVING AN ESSENTIALLY CONSTANT DIAMETER OF NOT MORE THAN 1000 ANGtiTROlViS Fred E. Luborsky, Schenectady, and Charles R. Morelock,
Ballston Spa, N.Y., assignors to General Electric Company, a corporation ofNew York Filed June 29, 1961, Ser. No. 120,648 2 Claims. (Cl. 75.5)
This invention relates to magnets and more particularly to permanent magnets constructed of nearly perfect single crystal whiskers.
The search for increasingly strong magnets and magnetic materials has, among other things, resulted in the use of single domain magnetic particles in the production of magnets having high coercive forces. Currently, the best single domain particles are produced by electrodeposition from mercury baths and while their magnetic properties are superior to any previously produced, some reduction of maximum magnetic properties were felt to occur due to the extremely irregular shapes of these particles.
It is a principal object of this invention to provide ferromagnetic whiskers having improved magnetic characteristics.
Another object of this invention is to provide an improved magnet composed of a plurality of ferromagnetic whiskers.
Other objects and advantages of this invention will be in part obvious and in part explained by reference to the accompanying specification and drawings.
In the drawings:
FIG. 1 is a graph showing the intrinsic coercive force of various types of small ferromagnetic particles as a function of the diameters of the particles; and
FIG. 2 is a greatly enlarged view showing the ferromagnetic whiskers of this invention.
The elongated ferromagnetic whiskers of this invention may be composed of iron, nickel, cobalt and alloys of these three metals. Probably the most important single characteristic which the whiskers must have to obtain higher coercive forces than heretofore is an essentially constant diameter throughout the entire length of each whisker. Thus, the whiskers are elongated, smooth and of substantially constant diameter throughout their entire lengths. Magnets can be produced from the whiskers by assembling a plurality of them together into one integral magnet body by conventional techniques. I
Referring to the graph shown in FIG. 1 of the drawings, the intrinsic coercive force of the whiskers of this invention is compared to the intrinsic coercive forces of the best small particles currently available. Curve illustrates the intrinsic coercive force, in oersteds, of generally spherically-shaped iron particles produced by electrodeposition into mercury. Curve 11 indicates similar properties for elongated magnetic particles also produced by deposition into mercury. A comparison of the values obtained from the two types of particles clearly indicates that the elongated configuration is much more effective in delivering high coercive forces than is the generally spherical geometry. The coercive forces shown by curve 11 for the mercury-deposited, elongated particles were obtained from specimens having the particles aligned with the long axis parallel to the direction of magnetic measurement, although substantially the same coercive forces are obtained from randomly distributed particles.
Curve 12 of the drawings indicates the intrinsic coercive forces of iron whiskers produced according to the present invention. The valves indicated by curve 12 were ob tained from specimens composed of elongated iron 3,132,022 Patented M-ay'5, 1964 ice whiskers whose long axes were randomly distributed with "respectto the direction of magnetic measurement. Additional measurements were made on specimens composed of elongated whiskers whose long axes were aligned generally parallel to the directionof magnetic measurement and it-was found that the coercive forces were substantially the same as the non-aligned Whiskers when the whisker diameters were on the order of about 500 A. At larger diameters, for example at 1500 A., the coercive force of an aligned whisker specimen was about 37.5 percent less than that of the non-aligned specimen. Theory indicates that the coercive force of aligned whiskers should become larger than the coercive force of randomly distributed whiskers when the diameter becomes'less than a critical diameter. The theoretical critical diameter is felt to be about 250 A., but test data indicates that the actual critical diameter is somewhat larger, for example between 400 and 500 A.
It is obvious, comparing curves 10-12, that for particles of similar diameters, those delivering the highest coercive forces are the whiskers of the present invention. Table I sets forth the magnetic properties of several whiskers produced in accordance with this invention.
These particles were stable in air due to the presence of an oxide coating on their surface which was only a few atoms thick. Because only a small amount of oxide is present, there is no detrimental effect by the oxide on the magnetic properties of the whiskers. It will be noted that the coercive force increases significantly as the diameter of the whiskers decreases, so that, for example, a
whisker having a diameter of about 250 A. has an intrinsic coercive force of about 3000 oerstedsa-t room temperature, this value being appreciably higher than has previously been obtainable in other small particles.
Referring to FIG. 2 of the drawings, the general shape of the whiskers is indicated. It will be noted that they are elongated, and substantially uniform in diameter throughout the entire length thereof. It is the small diameter and the uniformity of this diameter which makes it possible for the present whiskers to attain their high magnetic properties.
The whiskers of this invention may be produced by placing a source metal body and a substrate body in a closed chamber which is continuously evacuated. The chamber is then heated by any suitable means to a temperature such that the source metal body begins to evaporate. The vapor then resulting will be deposited upon the substrate body, which is maintained at a temperature sufficiently below that of the source metal body to provide for deposition and growth of whiskers from its surface. A complete description of the method for producing whiskers can be found in the copending application of Charles R. Morelock Serial No. 120,560, now abandoned, filed concurrently herewith and assigned to the same assignee as the present invention.
The process described in the patent application just referred to can be etfectively used on the magnetic materials described in this application, specifically iron, nickel, cobalt, and alloys of these metals, so that whiskers 3 of all of these materials can be obtained. For example, iron-cobalt whiskers containing 40 percent cobalt will have the saturation induction increased by about 15 percent with a corresponding increase in coercive force since the coercive force, due to shape anisotropy, is directly proportional to saturation induction. Thus, the maximum energy product will increase by about 32 percent.
Magnets can be produced using the present whiskers by agglomerating a plurality of the whiskers in a suitable matrix material. For example, a metal such as lead or a plastic matrix, may be used to combine the whiskers. Measurements were made of a magnet produced by combining a plurality of whiskers on an insulating plastic film and it was found to have coercive forces superior to mag nets previously produced. from existing small ferromagnetic particles.
What we claim as new and desire to secure by Letters Patent of the United States is:
1. As an article of manufacture, an elongated whisker of a metal selected from the group consisting of iron, nickel, cobalt and their alloys with each other, said whisker having an essentially constant diameter of not more than about 1000 A, throughout the length thereof. 2. An article as defined in claim 1 wherein the diameter does not exceed 500 A. I
References Cited in the file of this patent UNITED STATES PATENTS Paine et al Mar. 7, 1961 OTHER REFERENCES

Claims (1)

1. AS AN ARTICLE OF MANUFACTURE, AN ELONGATED WHISKER OF A METAL SELECTED FROM THE GROUP CONSISTING OF IRON, NICKEL, COBALT AND THEIR ALLOYS WITH EACH OTHER, SAID WHISKER HAVING AN ESSENTIALLY CONSTANT DIAMETER OF NOT MORE THAN ABOUT 1000 A. THROUGHOUT THE LENGTH THEREOF.
US120648A 1961-06-29 1961-06-29 Metal whiskers having an essentially constant diameter of not more than 1000 angstroms Expired - Lifetime US3132022A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US120648A US3132022A (en) 1961-06-29 1961-06-29 Metal whiskers having an essentially constant diameter of not more than 1000 angstroms
GB20503/62A GB981172A (en) 1961-06-29 1962-05-28 Magnets
DE19621464614 DE1464614B1 (en) 1961-06-29 1962-05-30 Method of manufacturing a permanent magnet
BE618632A BE618632A (en) 1961-06-29 1962-06-06 Permanent magnet
DK273962AA DK116143B (en) 1961-06-29 1962-06-19 Permanent magnet composed of a number of elongated ferromagnetic particles.
CH763162A CH409165A (en) 1961-06-29 1962-06-25 Permanent magnet

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US120648A US3132022A (en) 1961-06-29 1961-06-29 Metal whiskers having an essentially constant diameter of not more than 1000 angstroms

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BE (1) BE618632A (en)
CH (1) CH409165A (en)
DE (1) DE1464614B1 (en)
DK (1) DK116143B (en)
GB (1) GB981172A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3278342A (en) * 1963-10-14 1966-10-11 Westinghouse Electric Corp Method of growing crystalline members completely within the solution melt
US3434892A (en) * 1964-11-05 1969-03-25 Magnetfab Bonn Gmbh Directionally solidified permanent magnet alloys with aligned ferro-magnetic whiskers
US3542541A (en) * 1966-03-15 1970-11-24 United Aircraft Corp Whisker reinforced alloys and method of making the same
US3607451A (en) * 1969-10-08 1971-09-21 Us Army Process for forming iron whiskers of uniform high quality
US4113521A (en) * 1974-04-15 1978-09-12 International Business Machines Corporation Process for producing magnetic particles by vacuum evaporation of iron with collection on a magnetized surface
US4784703A (en) * 1983-08-26 1988-11-15 Grumman Aerospace Corporation Directional solidification and densification of permanent magnets having single domain size MnBi particles
US20040028936A1 (en) * 2001-03-08 2004-02-12 Masaki Kogiso Metalic nanowire and process for producing the same

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5376957A (en) * 1976-12-20 1978-07-07 Hitachi Maxell Magnetic metal iron powder and said manufacturing process
AU598370B2 (en) * 1987-06-12 1990-06-21 Minnesota Mining And Manufacturing Company Process for metal fibers

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2974104A (en) * 1955-04-08 1961-03-07 Gen Electric High-energy magnetic material

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2879154A (en) * 1956-10-02 1959-03-24 Franklin Inst Of The State Of Acicular metal particles and method of making the same

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2974104A (en) * 1955-04-08 1961-03-07 Gen Electric High-energy magnetic material

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3278342A (en) * 1963-10-14 1966-10-11 Westinghouse Electric Corp Method of growing crystalline members completely within the solution melt
US3434892A (en) * 1964-11-05 1969-03-25 Magnetfab Bonn Gmbh Directionally solidified permanent magnet alloys with aligned ferro-magnetic whiskers
US3542541A (en) * 1966-03-15 1970-11-24 United Aircraft Corp Whisker reinforced alloys and method of making the same
US3607451A (en) * 1969-10-08 1971-09-21 Us Army Process for forming iron whiskers of uniform high quality
US4113521A (en) * 1974-04-15 1978-09-12 International Business Machines Corporation Process for producing magnetic particles by vacuum evaporation of iron with collection on a magnetized surface
US4784703A (en) * 1983-08-26 1988-11-15 Grumman Aerospace Corporation Directional solidification and densification of permanent magnets having single domain size MnBi particles
US20040028936A1 (en) * 2001-03-08 2004-02-12 Masaki Kogiso Metalic nanowire and process for producing the same
US6858318B2 (en) * 2001-03-08 2005-02-22 Japan Science And Technology Corporation Metalic nanowire and process for producing the same

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GB981172A (en) 1965-01-20
CH409165A (en) 1966-03-15
DK116143B (en) 1969-12-15
DE1464614B1 (en) 1970-08-20
BE618632A (en) 1962-10-01

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