US2960470A - Method of manufacturing permanent magnets - Google Patents

Method of manufacturing permanent magnets Download PDF

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Publication number
US2960470A
US2960470A US554605A US55460555A US2960470A US 2960470 A US2960470 A US 2960470A US 554605 A US554605 A US 554605A US 55460555 A US55460555 A US 55460555A US 2960470 A US2960470 A US 2960470A
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United States
Prior art keywords
conglomerate
produce
magnetic field
anisotropic
permanent
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Expired - Lifetime
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US554605A
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English (en)
Inventor
Loosjes Robert
Veenemans Cornelis Frederik
Weber Gerard Hugo
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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Classifications

    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/26Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on ferrites
    • C04B35/2683Other ferrites containing alkaline earth metals or lead
    • 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
    • Y10T29/4902Electromagnet, transformer or inductor
    • Y10T29/49075Electromagnet, transformer or inductor including permanent magnet or core
    • Y10T29/49076From comminuted material

Definitions

  • Permanent magnets which substantially consist of simple crystals or mixed crystals having a constitution according to the formula M Ca O.6Fe O where M is one or more of the metals Ba, Sr or Pb and O.6x- -l, are known (see for example French patent specification No. 1,048,792 or U.S. Patent 2,672,777, and Philips Technical Review, volume 13, No. 7, January 1952, pages 194-208). It is also known (see French patent specification 1,080,514, or U.S. Patent 2,762,778) to manufacture crystal oriented or anisotropic permanent magnets which consist of such materials.
  • the constituent essential to the magnetic properties of the material is MFe O or MO.6Fe O M being barium, strontium or lead, or mixed crystals of two or more of those compounds. Calcium may be substituted for one of said metals in an amount up to 0.4 as an atomic fraction of those metals.
  • the formula of the essential constitutent may be written (to include calcium) as M Ca 0.6Fe O or x being greater than 0.6 and less than 1.
  • Other, and nonessential constituents may and often are present.
  • an excess of one of the oxides, preferably the bivalent metal oxide is employed in the starting mixture and this excess may remain as unreacted or partially reacted material in the final composition, for as noted in U.S. Patent 2,762,777, these materials may be prepared by mixing the oxides in a relatively wide range of proportions representing a significant departure from the ratio appearing in the constitutent essential to the magnetic properties of the material.
  • this material can be made anisotropic by orienting the crystals while they are in a mobile state. Preferably this is accomplished by suspending the material, in finely-divided form, in a liquid arranged between the poles of magnet. The material is preferably compressed during orientation and then sintered at a temperature of about 1100 to 1450 C. to form a coherent body.
  • This method has already led to the manufacture of permanent magnets having a (BH) -value exceeding 2 10 gauss-oersted. The mechanical properties also of the magnets thus produced are generally satisfactory. However, the method concerned does not give complete satisfaction when magnets of more or less complicated shape have to be manufactured. It should be borne in mind that the dies which must be used for carrying out said method must obviously also frequently break down owing to wear when comparatively large quantities of water are drawn off.
  • the invention solves the problem of manufacturing anisotropic permanent magnets of the kind described and having a comparatively complicated structure, by the use of a method which comprises features both of the wet and of the dry moulding method.
  • a method which comprises features both of the wet and of the dry moulding method.
  • the permanent magnet powder is suspended in an indifferent liquid, for example water, and the liquid is removed from the suspension, for example by filtering, while the suspension is arranged between the poles of a magnet.
  • an indifferent liquid for example water
  • the liquid is removed from the suspension, for example by filtering, while the suspension is arranged between the poles of a magnet.
  • a conglomerate is obtained which has a magnetic directive effect: it is magnetically anisotropic.
  • the conglomerate is granulated, for example by means of a sieve, through which the solid substance is pressed.
  • Suitable substances are particularly solid organic substances which are liquefied under a slight pressure (of less than 500 kg./cm.
  • Camphor or chemically related substances have proved very suitable for the purpose concerned; thus, camphor is liquefied at a pressure of from to kg./cm.
  • the camphor or similar substance are added in the form of an alcoholic solution, for example a solution of 2% by weight, which is sprayed over the granulate required to be molded.
  • camphor or a similar substance use may, for example, be made of paraflin.
  • Example I Finely powdered barium carbonate, BaCO and ferric oxide, Fe O are thoroughly mixed at a ratio of 1.1:6 mol. The mixture is compressed to form blocks and these blocks are fired for approximately 15 minutes at 1280 C. After cooling, the blocks are pulverised and the obtained powder is worked up into a suspension after the addition of a small amount of water and 1% by weight of calcium carbonate, CaCO From this suspension the water is removed by filtering in a magnetic field, after which the filter cake is dried by exposure to air. The airdried substance is subsequently pressed through a sieve having meshes of approximately 2 x 2 mms. The grains produced are compressed in a magnetic field and finally fired for approximately 5 minutes at approximately 1250" C.
  • the properties of the permanent magnet produced by this method were as follows:
  • a permanent anisotropic magnet the steps of suspending in a chemically inert liquid crystals of a material having a composition in which M is at least one of the metals selected from the group consisting of barium, strontium and lead, and x is at least equal to 0.6 and not greater than 1, filtering the liquid under the action of a magnetic field to thereby produce a magnetically anisotropic conglomerate, granulating the conglomerate, adding to the granulated conglomerate an organic binder adapted to increase cohesion between grains without increasing friction therebetween during molding, molding the conglomerate under the action of a magnetic field to produce a magnetically anisotropic body, and sintering said body at a temperature of about 1100 to 1400 C. to produce a highly-coherent permanent magnet body having a (BI-l) value exceeding approximately 1.5 x10 gauss-oersted.
  • a permanent anisotropic magnet In the manufacture of a permanent anisotropic magnet, the steps of suspending in a chemically inert liquid crystals of a material having a composition in which M is at least one of the metals selected from the group consisting of barium, strontium and lead, and x is at least equal to 0.6 and not greater than 1, filtering the liquid under the action of a magnetic field to thereby produce a magnetically anisotropic conglomerate, granulating the conglomerate, adding to the granulated conglomerate an organic binder adapted to be liquefied at a pressure of less than about 500 lag/cm.
  • a permanent anisotropic magnet the steps of suspending in a chemically inert liquid crystals of a material having a composition in which M is at least one of the metals selected from the group consisting of barium, strontium and lead, and x is at least equal to 0.6 and not greater than 1, filtering the liquid under the action of a magnetic field to thereby produce a magnetically anisotropic conglomerate, granulating the conglomerate, adding camphor to the granulated conglomerate, molding the conglomerate under the action of a magnetic field to produce a magnetically anisotropic body, and sintering said body at a temperature of about ll00 to 1400 C. to produce a highly-coherent permanent magnet body having a (BI-U value exceeding ap proximately 1.5 10 gauss-oersted.
  • a permanent anisotropic magnet the steps of suspending in a chemically inert liquid crystals of a material having a composition in which M is at least one of the metals selected from the group consisting of barium, strontium and lead, and x is at least equal to 0.6 and not greater than 1, filtering the liquid under the action of a magnetic field to thereby produce a magnetically anisotropic conglomerate, granulating the conglomerate, adding an alcoholic solution of camphor to the granulated conglomerate, molding the conglomerate under the action of a magnetic field to produce a mag netically anisotropic body, and sintering said body at a temperature of about 1100 to 1400 C. to produce a highly-coherent permanent magnet body having a (EH) value exceeding approximately 1.5 10 gaussoersted.
  • a permanent anisotropic magnet the steps of suspending in a chemically inert liquid crystals of a material having a composition in which M is at least one of the metals selected from the group consisting of barium, strontium and lead, and x is at least equal to 0.6 and not greater than 1, filtering the liquid under the action of a magnetic field to thereby produce a magnetically anisotropic conglomerate, granulating the conglomerate, spraying the granulated conglomerate with an alcoholic camphor solution, molding the conglomerate under the action of magnetic field to produce a magnetically anisotropic body, and sintering said body at a temperature of about 1100 to 1400 C. to produce a highly-coherent permanent magnet body having a (BH) value exceeding approximately 1.5 10 gauss oersted.
  • M is at least one of the metals selected from the group consisting of barium, strontium and lead
  • x is at least equal to 0.6 and not greater than 1
  • a permanent anisotropic mag- M Ca 0.61 6 0 in which M is at least one of the metals selected firom the group consisting of barium, strontium and lead, and x is at least equal to 0.6 and not greater than 1, filtering the liquid under the action of a magnetic field to thereby produce a magnetically anisotropic conglomerate, granulating the conglomerate, adding paraflin to the granulated conglomerate, molding the conglomerate under the action of a magnetic field to produce a magnetically anisotropic body, and sintering said body at a temperature of about 1100 to 1400 C. to produce a highly-coherent permanent magnet body having a (BH),,,,,, value exceeding approximately 1.5 X gauss-oersted.
  • BH highly-coherent permanent magnet body having a
  • a permanent anisotropic magnet the steps of suspending in a chemically inert liquid crystals of a material having a composition in which x is at least equal to 0.6 and not greater than 1, filtering the liquid under the action of -a magnetic field to thereby produce a magnetically anisotropic conglomerate, granulating the conglomerate, spraying the granulated conglomerate with an alcoholic camphor solution, molding the conglomerate under the action of a magnetic field to produce a magnetically anisotropic body, and sintering said body at a temperature of about 1100 to 1400 C. to produce a highly-coherent permanent magnet body having a (BH) value exceeding approximately 1.5 x10 gaussoersted.
  • BH highly-coherent permanent magnet body having a (BH) value exceeding approximately 1.5 x10 gaussoersted.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Hard Magnetic Materials (AREA)
  • Magnetic Ceramics (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)
  • Magnetic Treatment Devices (AREA)
US554605A 1954-12-21 1955-12-21 Method of manufacturing permanent magnets Expired - Lifetime US2960470A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL783237X 1954-12-21

Publications (1)

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US2960470A true US2960470A (en) 1960-11-15

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US554605A Expired - Lifetime US2960470A (en) 1954-12-21 1955-12-21 Method of manufacturing permanent magnets

Country Status (8)

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US (1) US2960470A (fr)
BE (1) BE543773A (fr)
CH (1) CH347585A (fr)
DE (1) DE1028708B (fr)
FR (1) FR1144257A (fr)
GB (1) GB783237A (fr)
LU (1) LU34051A1 (fr)
NL (2) NL86918C (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3113927A (en) * 1960-10-18 1963-12-10 Westinghouse Electric Corp Ferrite magnets
US3136033A (en) * 1961-07-17 1964-06-09 Allen Bradley Co Method and apparatus for producing permanent magnets
US4117058A (en) * 1976-12-03 1978-09-26 General Motors Corporation Method of making boron containing strontium ferrite

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE521244A (fr) * 1952-07-07
BE516598A (fr) *
US2535025A (en) * 1949-10-06 1950-12-26 Steatite Res Corp Process of treating ferrites
US2565861A (en) * 1947-09-26 1951-08-28 Rca Corp Magnetic materials
FR1080514A (fr) * 1951-12-21 1954-12-09 Philips Nv Aimant permanent et son procédé de fabrication
US2705701A (en) * 1952-11-28 1955-04-05 Henry L Crowley & Company Inc Method for preparing magnetic compositions
US2714580A (en) * 1951-09-19 1955-08-02 Mallory & Co Inc P R Magnetic materials and methods of making the same
US2723238A (en) * 1952-08-19 1955-11-08 Rca Corp Manganese zinc ferrospinel compositions, including copper oxide
US2762777A (en) * 1950-09-19 1956-09-11 Hartford Nat Bank & Trust Co Permanent magnet and method of making the same
US2849312A (en) * 1954-02-01 1958-08-26 Milton J Peterman Method of aligning magnetic particles in a non-magnetic matrix
US2854412A (en) * 1954-12-23 1958-09-30 Philips Corp Method of making a permanent magnet

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE516598A (fr) *
US2565861A (en) * 1947-09-26 1951-08-28 Rca Corp Magnetic materials
US2535025A (en) * 1949-10-06 1950-12-26 Steatite Res Corp Process of treating ferrites
US2762777A (en) * 1950-09-19 1956-09-11 Hartford Nat Bank & Trust Co Permanent magnet and method of making the same
US2714580A (en) * 1951-09-19 1955-08-02 Mallory & Co Inc P R Magnetic materials and methods of making the same
FR1080514A (fr) * 1951-12-21 1954-12-09 Philips Nv Aimant permanent et son procédé de fabrication
BE521244A (fr) * 1952-07-07
US2723238A (en) * 1952-08-19 1955-11-08 Rca Corp Manganese zinc ferrospinel compositions, including copper oxide
US2705701A (en) * 1952-11-28 1955-04-05 Henry L Crowley & Company Inc Method for preparing magnetic compositions
US2849312A (en) * 1954-02-01 1958-08-26 Milton J Peterman Method of aligning magnetic particles in a non-magnetic matrix
US2854412A (en) * 1954-12-23 1958-09-30 Philips Corp Method of making a permanent magnet

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3113927A (en) * 1960-10-18 1963-12-10 Westinghouse Electric Corp Ferrite magnets
US3136033A (en) * 1961-07-17 1964-06-09 Allen Bradley Co Method and apparatus for producing permanent magnets
US4117058A (en) * 1976-12-03 1978-09-26 General Motors Corporation Method of making boron containing strontium ferrite

Also Published As

Publication number Publication date
NL86918C (fr)
NL193422A (fr)
DE1028708B (de) 1958-04-24
CH347585A (de) 1960-07-15
FR1144257A (fr) 1957-10-11
BE543773A (fr)
GB783237A (en) 1957-09-18
LU34051A1 (fr)

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