US3663317A - Method of making a permanent-magnetisable body of compressed fine particles of a compound of m and r - Google Patents

Method of making a permanent-magnetisable body of compressed fine particles of a compound of m and r Download PDF

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Publication number
US3663317A
US3663317A US90512A US3663317DA US3663317A US 3663317 A US3663317 A US 3663317A US 90512 A US90512 A US 90512A US 3663317D A US3663317D A US 3663317DA US 3663317 A US3663317 A US 3663317A
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United States
Prior art keywords
permanent
compound
powder
fine particles
ageing
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Expired - Lifetime
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US90512A
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English (en)
Inventor
Frans Frederik Westendorp
Antonius Gregorius Rijnbeek
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US Philips Corp
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US Philips Corp
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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
    • 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
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/02—Compacting only
    • B22F3/04—Compacting only by applying fluid pressure, e.g. by cold isostatic pressing [CIP]
    • 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
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • 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
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49075—Electromagnet, transformer or inductor including permanent magnet or core
    • Y10T29/49076—From comminuted material

Definitions

  • the invention relates to a method of manufacturing a permanent-magnetisable body of fine particles of a compound of M and R, the range of existence of which is integral with that of the compound M R having a hexagonal crystal structure, in which M represents Co or a combination of Co with one or more of the elements Fe, Ni and Cu and R represents one or more of the elements of the rare earth metals and/or Th, in which method a casting of the alloy concerned of M and R is ground to a powder of the desired granular size, the powder being pre-densified and orientated simultaneously or subsequently in a magnetic field, after which it is compressed by an isostatic pressure of at least kbar and finally plastically deformed slightly, while said isostatic pressure is maintained.
  • the rare earths are to include also the element Y.
  • range of existence is to denote herein a range of concentrations within which for a continuous series of compounds the same crystal structure can be obtained for 100 percent.
  • the resultant magnetic body described therein may have a relative density of 97 percent at the most, which is to be understood to mean that the density of the body is 97 percent of the theoretical density of the M-R compound concerned.
  • Magnetic bodies thus manufactured have, however, the disadvantageous property that the coercive force decreases with time: there occurs a so-called ageing process.
  • this ageing is referred to and recognized as a disadvantage to practical use of the magnetic bodies. This ageing increases with increasing temperature. However, even at room temperature ageing occurs to an undesirable extent.
  • Said advantageous effect of said step during the grinding process on ageing is the more surprising as, when considering oxidation in air as being the cause of ageing, it cannot be accounted for how any oxidation, which occurs only for a short time i.e. during the grinding process, may be the cause of the ageing effect in a later stage i.e. when the magnetic body has been manufactured.
  • Castings of the compound SmCo were ground by means of a coffee mill in a so-called glove box (gas-tight space in which protrude two gloves fastened by the sleeves in holes of the wall and being thus accessible from without) into powder of an average granular size of about 3 pm.
  • the glove box was filled with He gas containing less than 5 ppm of oxygen and/or water vapour.
  • the resultant powder, still in the glove box, was poured into a lead holder, orientated in a magnetic field and pre-densified by an isostatic pressure of 8 kbar. Then the lead holder with the block resulting from the compression, was
  • the resultant permanent-magnetisable body was found to have a relative density of 97 percent.
  • the body was then exposed to a temperature of C in air. After 10 minutes the coercive force was found to be 15.900 Oe. After l00, 1,000 and 10,000 minutes the coercive forces were again measured.
  • Graph (a) of FIG. 1 illustrates the variation of the coercive force as a function of time. It should be noted that the ageing effect occurs about 2,000 times more rapidly at a temperature of 100 C than at room temperature. Apart from the time associated with a temperature of 100 C the time associated with a temperature of 27 is therefore plotted on the abscissa.
  • the graph of FIG. 1 also shows an ageing curve (b) measured on a permanentmagnetisable body having also a density of 97 percent and made from a powder ground by the same method and having the same chemical composition and the same average granular size, however, not being ground under the conditions characteristic of the method according to the invention.
  • the graph of FIG. 2 illustrates for a few magnetic bodies the relationship between the coercive force at the time t(H (t)) and the coercive force at the time t 10 minutes (H,( 10)) and the time during which the magnetic bodies were exposed to air at 100 C.
  • the magnetic bodies having densities of 98.5 to 99.9 percent were manufactured by the method according to the invention, whereas the bodies having densities of 95.0 and 97.0 percent were manufactured by the method hitherto known.
  • An additional advantage of permanent magnets manufactured from bodies having such high densities resides in that the energy product (BH),,,,, as compared with that of permanent magnets formed from magnetic bodies differing only in density therefrom, is higher.
  • the invention relates furthermore to permanent-magnetisable bodies manufactured by the method according to the invention and particularly to such bodies having a relative density of more than 99 percent.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Hard Magnetic Materials (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Powder Metallurgy (AREA)
US90512A 1969-12-20 1970-11-18 Method of making a permanent-magnetisable body of compressed fine particles of a compound of m and r Expired - Lifetime US3663317A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6919154A NL6919154A (xx) 1969-12-20 1969-12-20

Publications (1)

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US3663317A true US3663317A (en) 1972-05-16

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US90512A Expired - Lifetime US3663317A (en) 1969-12-20 1970-11-18 Method of making a permanent-magnetisable body of compressed fine particles of a compound of m and r

Country Status (10)

Country Link
US (1) US3663317A (xx)
AU (1) AU2352970A (xx)
BE (1) BE760570A (xx)
CH (1) CH544388A (xx)
DE (1) DE2059303A1 (xx)
ES (1) ES386582A1 (xx)
FR (1) FR2073860A5 (xx)
GB (1) GB1309958A (xx)
NL (1) NL6919154A (xx)
SE (1) SE372995B (xx)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3771221A (en) * 1971-12-03 1973-11-13 Bbc Brown Boveri & Cie Method and apparatus for producing fine-particle permanent magnets
US3873379A (en) * 1972-07-12 1975-03-25 Hitachi Metals Ltd Method of producing rare earth-cobalt permanent magnet using special cooling rates
US3901742A (en) * 1974-04-11 1975-08-26 Gen Electric Removal of lubricants and binders from sinterable powder components
US4063970A (en) * 1967-02-18 1977-12-20 Magnetfabrik Bonn G.M.B.H. Vormals Gewerkschaft Windhorst Method of making permanent magnets
US4075042A (en) * 1973-11-16 1978-02-21 Raytheon Company Samarium-cobalt magnet with grain growth inhibited SmCo5 crystals
US4104787A (en) * 1977-03-21 1978-08-08 General Motors Corporation Forming curved wafer thin magnets from rare earth-cobalt alloy powders
US4152178A (en) * 1978-01-24 1979-05-01 The United States Of America As Represented By The United States Department Of Energy Sintered rare earth-iron Laves phase magnetostrictive alloy product and preparation thereof
WO1992005903A1 (en) * 1990-10-09 1992-04-16 Iowa State University Research Foundation, Inc. A melt atomizing nozzle and process
US5228620A (en) * 1990-10-09 1993-07-20 Iowa State University Research Foundtion, Inc. Atomizing nozzle and process
US5240513A (en) * 1990-10-09 1993-08-31 Iowa State University Research Foundation, Inc. Method of making bonded or sintered permanent magnets
US5242508A (en) * 1990-10-09 1993-09-07 Iowa State University Research Foundation, Inc. Method of making permanent magnets

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3463678A (en) * 1966-08-15 1969-08-26 Gen Electric Method for improving magnetic properties of cobalt-yttrium or cobalt-rare earth metal compounds
US3523836A (en) * 1967-01-21 1970-08-11 Philips Corp Permanent magnet constituted of fine particles of a compound m5r
US3540945A (en) * 1967-06-05 1970-11-17 Us Air Force Permanent magnets

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3463678A (en) * 1966-08-15 1969-08-26 Gen Electric Method for improving magnetic properties of cobalt-yttrium or cobalt-rare earth metal compounds
US3523836A (en) * 1967-01-21 1970-08-11 Philips Corp Permanent magnet constituted of fine particles of a compound m5r
US3540945A (en) * 1967-06-05 1970-11-17 Us Air Force Permanent magnets

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4063970A (en) * 1967-02-18 1977-12-20 Magnetfabrik Bonn G.M.B.H. Vormals Gewerkschaft Windhorst Method of making permanent magnets
US3771221A (en) * 1971-12-03 1973-11-13 Bbc Brown Boveri & Cie Method and apparatus for producing fine-particle permanent magnets
US3873379A (en) * 1972-07-12 1975-03-25 Hitachi Metals Ltd Method of producing rare earth-cobalt permanent magnet using special cooling rates
US4075042A (en) * 1973-11-16 1978-02-21 Raytheon Company Samarium-cobalt magnet with grain growth inhibited SmCo5 crystals
US3901742A (en) * 1974-04-11 1975-08-26 Gen Electric Removal of lubricants and binders from sinterable powder components
US4123297A (en) * 1977-03-21 1978-10-31 General Motors Corporation Forming curved thin magnets from rare earth-transition metal powders
US4104787A (en) * 1977-03-21 1978-08-08 General Motors Corporation Forming curved wafer thin magnets from rare earth-cobalt alloy powders
US4152178A (en) * 1978-01-24 1979-05-01 The United States Of America As Represented By The United States Department Of Energy Sintered rare earth-iron Laves phase magnetostrictive alloy product and preparation thereof
WO1992005903A1 (en) * 1990-10-09 1992-04-16 Iowa State University Research Foundation, Inc. A melt atomizing nozzle and process
US5125574A (en) * 1990-10-09 1992-06-30 Iowa State University Research Foundation Atomizing nozzle and process
US5228620A (en) * 1990-10-09 1993-07-20 Iowa State University Research Foundtion, Inc. Atomizing nozzle and process
US5240513A (en) * 1990-10-09 1993-08-31 Iowa State University Research Foundation, Inc. Method of making bonded or sintered permanent magnets
US5242508A (en) * 1990-10-09 1993-09-07 Iowa State University Research Foundation, Inc. Method of making permanent magnets
US5470401A (en) * 1990-10-09 1995-11-28 Iowa State University Research Foundation, Inc. Method of making bonded or sintered permanent magnets

Also Published As

Publication number Publication date
CH544388A (de) 1973-11-15
ES386582A1 (es) 1973-03-16
GB1309958A (en) 1973-03-14
SE372995B (xx) 1975-01-20
DE2059303A1 (de) 1971-06-24
BE760570A (fr) 1971-06-18
NL6919154A (xx) 1971-06-22
FR2073860A5 (xx) 1971-10-01
AU2352970A (en) 1972-06-22

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