US3563899A - Permanent magnet material having strontium ferrite base - Google Patents

Permanent magnet material having strontium ferrite base Download PDF

Info

Publication number
US3563899A
US3563899A US732880A US3563899DA US3563899A US 3563899 A US3563899 A US 3563899A US 732880 A US732880 A US 732880A US 3563899D A US3563899D A US 3563899DA US 3563899 A US3563899 A US 3563899A
Authority
US
United States
Prior art keywords
permanent magnet
strontium
magnet material
strontium ferrite
ferrite base
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
US732880A
Inventor
Roger Frank Coe
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.)
ZF International UK Ltd
Original Assignee
Lucas Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Lucas Industries Ltd filed Critical Lucas Industries Ltd
Application granted granted Critical
Publication of US3563899A publication Critical patent/US3563899A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/26—Shaped 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
    • C04B35/2683—Other ferrites containing alkaline earth metals or lead
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G49/00—Compounds of iron
    • C01G49/0018—Mixed oxides or hydroxides
    • C01G49/0036—Mixed oxides or hydroxides containing one alkaline earth metal, magnesium or lead
    • 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
    • H01F1/10—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 non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/42—Magnetic properties
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
    • C04B2235/3208—Calcium oxide or oxide-forming salts thereof, e.g. lime
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
    • C04B2235/3213—Strontium oxides or oxide-forming salts thereof
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3217—Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/44—Metal salt constituents or additives chosen for the nature of the anions, e.g. hydrides or acetylacetonate
    • C04B2235/444—Halide containing anions, e.g. bromide, iodate, chlorite
    • C04B2235/445—Fluoride containing anions, e.g. fluosilicate
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/44—Metal salt constituents or additives chosen for the nature of the anions, e.g. hydrides or acetylacetonate
    • C04B2235/447—Phosphates or phosphites, e.g. orthophosphate, hypophosphite
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
    • C04B2235/605—Making or treating the green body or pre-form in a magnetic field

Definitions

  • a permanent magnet material having a strontium ferrite base is known, and it is also known that additives of various kinds improve the properties of a magnet manufactured from such material.
  • the slurry was then wet pressed in a magnetic field of 8000 oersteds at a pressure of 3 tons per square inch, and was dried and sintered at a maximum temperature of 1230 C., and then cooled to room temperature. To avoid cracking of the magnet formed as a result of dimensional changes taking place in the sintering and cooling process, the heating and cooling were carefully controlled in known manner.
  • the aluminium oxide used in the mixture is a grain growth inhibitor and the calcium fluoride is a flux agent. These additives are known in themselves, but the presence of the strontium phosphate leads to greatly improved results.
  • the properties of a magnet of this general kind are assessed by quoting the values of the remanence B and the field strength of disappearance of magnetisation or intrinsic coercivity H and the values of these parameters in the example quoted were 4160 gauss and 3900 oersted respectively.
  • the amount of phosphate which must be added for best results depends on the exact nature of the starting material.
  • the preferred range is 0.4% to 0.6% but amounts up to 3% can be added.
  • An addition of 0.01% can be regarded as a suitable lower limit.
  • a permanent magnet material consisting essentially of strontium ferrite and from 0.01% to 3% by weight of strontium phosphate.

Abstract

UP TO 3% OF STRONIUM PHOSPHATE IS ADDED TO PERMANENT MAGNET MATERIAL OF KNOWN FROM HAVING A STRONTIUM FERRITE BASE. THE ADDITION OF THE STRONTIUM PHOSPHATE IS FOUND TO GIVE CONSIDERABLY IMPROVED MAGNETIC PROPERTIES.

Description

United States Patent U.S. Cl. 252--62.63 3 Claims ABSTRACT OF THE DISCLOSURE Up to 3% by weight of strontium phosphate is added to permanent magnet material of known form having a strontium ferrite base. The addition of the strontium phosphate is found to give considerably improved magnetic properties.
A permanent magnet material having a strontium ferrite base is known, and it is also known that additives of various kinds improve the properties of a magnet manufactured from such material. We have now found that the magnetic properties of a magnet formed from a strontium based material can be considerably improved if strontium phosphate is added to the starting material.
In one example, 439 grams of ferric oxide, 74 grams of strontium carbonate, 5.22 grams of calcium fluoride, 1.30 grams of aluminium oxide and 2.61 grams of strontium phosphate were wet mixed for two hours in proportions of 50% water by volume to 50% of the mixture. The mixture was then dried to provide a powder which was calcined at 1260 C. for one hour. After cooling, the powder was wet-ball milled using steel balls of 6 inch diameter to a particle size less than 1 micron, the liquid medium being water together with a surface active agent, for example that sold under the trade name Daxad 30. This process was continued for 12 hours. The slurry was then wet pressed in a magnetic field of 8000 oersteds at a pressure of 3 tons per square inch, and was dried and sintered at a maximum temperature of 1230 C., and then cooled to room temperature. To avoid cracking of the magnet formed as a result of dimensional changes taking place in the sintering and cooling process, the heating and cooling were carefully controlled in known manner.
The aluminium oxide used in the mixture is a grain growth inhibitor and the calcium fluoride is a flux agent. These additives are known in themselves, but the presence of the strontium phosphate leads to greatly improved results. The properties of a magnet of this general kind are assessed by quoting the values of the remanence B and the field strength of disappearance of magnetisation or intrinsic coercivity H and the values of these parameters in the example quoted were 4160 gauss and 3900 oersted respectively.
It is known that variation of the sintering temperature can improve the value of intrinsic coercivity at the expense of remanence or vice versa, and this variation occurs with or without the phosphate addition. By way of example, when the specific example mentioned above was repeated at a sintering temperature at 1200 C., the values of remanence and intrinsic coercivity obtained were 3890 gauss and 4325 oersted respectively.
The advantages obtained according to the invention are best seen by considering the properties of strontium-based ferrite magnets which are commercially available. The best of these has parameters of 3720 gauss and 3075 oersted both of which are inferior to the parameters obtained using the invention. Of course either of the parameters can be improved at the expense of the other, but nevertheless the improvement obtained using strontium phosphate will be apparent. The invention also gives better results than the use of strontium sulphate as described in British Pat. No. 995,374. Using sulphate, the intrinsic coercivity for a remanence of 4160 gauss is 3350 oersted, as compared with 3900 in the example above.
The amount of phosphate which must be added for best results depends on the exact nature of the starting material. The preferred range is 0.4% to 0.6% but amounts up to 3% can be added. An addition of 0.01% can be regarded as a suitable lower limit.
Having thus described my invention what I claim as new and desire to secure by Letters Patent is:
1. A permanent magnet material consisting essentially of strontium ferrite and from 0.01% to 3% by weight of strontium phosphate.
2. A permanent magnet material as claimed in claim 1 in which the amount of strontium phosphate is from 0.4% to 0.6% by weight.
3. A permanent magnet formed from the material as claimed in claim 1.
References Cited FOREIGN PATENTS 995,374 6/1965 Great Britain 25262.63
TQBIAS E. LEVOW, Primary Examiner I. COOPER, Assistant Examiner
US732880A 1967-06-02 1968-05-29 Permanent magnet material having strontium ferrite base Expired - Lifetime US3563899A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB25592/67A GB1216675A (en) 1967-06-02 1967-06-02 Permanent magnet material having strontium ferrite base

Publications (1)

Publication Number Publication Date
US3563899A true US3563899A (en) 1971-02-16

Family

ID=10230184

Family Applications (1)

Application Number Title Priority Date Filing Date
US732880A Expired - Lifetime US3563899A (en) 1967-06-02 1968-05-29 Permanent magnet material having strontium ferrite base

Country Status (5)

Country Link
US (1) US3563899A (en)
DE (1) DE1771479B2 (en)
FR (1) FR1566144A (en)
GB (1) GB1216675A (en)
NL (1) NL139125B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3846323A (en) * 1971-09-01 1974-11-05 Bosch Gmbh Robert Process for making a permanent magnet material
US20030095581A1 (en) * 2001-11-19 2003-05-22 Glyn Edwards Laser rod pump chamber and method
EP2453449A1 (en) * 2009-07-08 2012-05-16 TDK Corporation Ferrite magnetic material
CN104140258A (en) * 2014-08-04 2014-11-12 梁家新 Recycling and preparing method of permanent magnetic ferrite and magnet thereof

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3846323A (en) * 1971-09-01 1974-11-05 Bosch Gmbh Robert Process for making a permanent magnet material
US20030095581A1 (en) * 2001-11-19 2003-05-22 Glyn Edwards Laser rod pump chamber and method
US6693940B2 (en) * 2001-11-19 2004-02-17 Gsi Lumonics Ltd. Laser rod pump chamber and method
EP2453449A1 (en) * 2009-07-08 2012-05-16 TDK Corporation Ferrite magnetic material
CN102473499A (en) * 2009-07-08 2012-05-23 Tdk株式会社 Ferrite magnetic material
US20120161062A1 (en) * 2009-07-08 2012-06-28 Tdk Corporation Ferrite magnetic material
EP2453449A4 (en) * 2009-07-08 2013-04-03 Tdk Corp Ferrite magnetic material
US8834738B2 (en) * 2009-07-08 2014-09-16 Tdk Corporation Ferrite magnetic material
US9336933B2 (en) 2009-07-08 2016-05-10 Tdk Corporation Ferrite magnetic material
CN104140258A (en) * 2014-08-04 2014-11-12 梁家新 Recycling and preparing method of permanent magnetic ferrite and magnet thereof

Also Published As

Publication number Publication date
NL139125B (en) 1973-06-15
DE1771479B2 (en) 1972-03-09
FR1566144A (en) 1969-05-02
GB1216675A (en) 1970-12-23
NL6807759A (en) 1968-12-03
DE1771479A1 (en) 1972-03-09

Similar Documents

Publication Publication Date Title
Miller Distribution of cations in spinels
GB747724A (en) Improvements in or relating to non-metallic permanent magnets
Mee et al. Single‐Domain Properties in Hexagonal Ferrites
US2837483A (en) Method of making a permanent magnet
US2715109A (en) Ferromagnetic ceramic materials with hysteresis loops of rectangular shape
USRE26153E (en) Field strength
US4063970A (en) Method of making permanent magnets
US3855374A (en) Method of making magnetically-anisotropic permanent magnets
US3563899A (en) Permanent magnet material having strontium ferrite base
WO2022038531A1 (en) A permanent magnetic material and a method for its preparation
JP2001135512A (en) Ferrite magnet powder, magnet using the magnet powder and method of manufacturing both
JPS5820890B2 (en) Manufacturing method of ferrite particles
GB747737A (en) Improvements in or relating to methods of manufacturing non-metallic permanent magnets
US4279763A (en) Process of preparing ferrite powders
US3412461A (en) Method for making ferrite magnets
Özkan et al. The effect of B2O3 addition on the direct sintering of barium hexaferrite
US4259197A (en) Process of preparing ferrite powders
US3337461A (en) Two-phase ferrite magnet composition and method for preparing same
JPH01112705A (en) Manufacture of oxide permanent magnet
US3036008A (en) Permanent magnet ferrite
JPS6217841B2 (en)
US3093453A (en) Ferrite material containing fluorine
US3804767A (en) Method of manufacturing ceramic magnets containing strontium or barium ferrite
US4117058A (en) Method of making boron containing strontium ferrite
JPH11307331A (en) Ferrite magnet