EP0394020A2 - Particules en ferrite et composite ferrite-résine pour noyau magnétique à liant et procédé de leur fabrication - Google Patents

Particules en ferrite et composite ferrite-résine pour noyau magnétique à liant et procédé de leur fabrication Download PDF

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Publication number
EP0394020A2
EP0394020A2 EP90304167A EP90304167A EP0394020A2 EP 0394020 A2 EP0394020 A2 EP 0394020A2 EP 90304167 A EP90304167 A EP 90304167A EP 90304167 A EP90304167 A EP 90304167A EP 0394020 A2 EP0394020 A2 EP 0394020A2
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EP
European Patent Office
Prior art keywords
ferrite
mol
particles
ferrite particles
resin
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.)
Granted
Application number
EP90304167A
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German (de)
English (en)
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EP0394020A3 (fr
EP0394020B1 (fr
Inventor
Shigehisa Yamamoto
Masaru Kawabata
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.)
Toda Kogyo Corp
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Toda Kogyo Corp
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Publication date
Priority claimed from JP1101204A external-priority patent/JP2743009B2/ja
Priority claimed from JP2050715A external-priority patent/JP2893351B2/ja
Application filed by Toda Kogyo Corp filed Critical Toda Kogyo Corp
Publication of EP0394020A2 publication Critical patent/EP0394020A2/fr
Publication of EP0394020A3 publication Critical patent/EP0394020A3/fr
Application granted granted Critical
Publication of EP0394020B1 publication Critical patent/EP0394020B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H01F1/12—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 soft-magnetic materials
    • H01F1/34—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 soft-magnetic materials non-metallic substances, e.g. ferrites
    • H01F1/36—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 soft-magnetic materials non-metallic substances, e.g. ferrites in the form of particles
    • H01F1/37—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 soft-magnetic materials non-metallic substances, e.g. ferrites in the form of particles in a bonding agent
    • 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
    • H01F1/12—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 soft-magnetic materials
    • H01F1/34—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 soft-magnetic materials non-metallic substances, e.g. ferrites
    • H01F1/36—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 soft-magnetic materials non-metallic substances, e.g. ferrites in the form of particles

Definitions

  • the present invention relates to ferrite particles suitable for a bonded magnetic core, a process for producing the particles and a ferrite resin composite containing the particles.
  • Ferrite particles and a ferrite resin composite are mainly used as a magnetic core material of an induction coil for various electronic machines such as a computer, communications apparatus and home appliances, and a magnetic core material of a transformer, etc.
  • a bonded magnetic core which is superior to a sintered magnetic core in dimensional stability, processability and resistance to brittleness, is advantageous in that a small or thin core is realizable and mass production of even cores having a complicated shape is easy.
  • the demands for providing lighter-weight, miniaturization and higher-accuracy cores which are to be produced by making good use of these advantages has been increasing.
  • a bonded magnetic core is generally produced by kneading a magnetic material with a resin such as nylon and phenol, and molding the resultant mixture by compression molding or injection molding.
  • an oxide material such as Mn-Zn ferrite and Ni-Zn ferrite is used.
  • Such an oxide magnetic material is generally obtained by mixing a main raw material such as Fe2O3, MnO, ZnO and NiO in advance by wet or dry blending so as to have a desired composition, granulating the resultant mixture into particles having a diameter of about several mm to several ten mm, calcining the obtained particles and pulverizing the calcined particles into particles having an average particle diameter of several ⁇ m to several hundred ⁇ m.
  • a bonded magnetic core is required to have a magnetic permeability as large as possible. This demand has been increasing with the recent demand for a bonded magnetic core having a higher capacity.
  • a bonded magnetic core is composed of a magnetic material combined with a resin such as nylon and phenol, as described above, and that various properties, in particular, the magnetic permeability of the bonded core has a closer relation to and is more influenced by the properties of the magnetic material used in comparison with a sintered core. Therefore, in order to obtain a bonded magnetic core having a large magnetic permeability, it is advantageous to use ferrite particles having a large magnetic permeability as a magnetic material.
  • the ferrite resin composite is required to have an excellent fluidity.
  • the crystal grains grow as large as several hundred ⁇ m and become non-uniform.
  • the crystal grain contains many pores. Due to the non-uiniform crystal grains and the presence of many pores, the magnetic permeability is lowered. As a result the obtained ferrite particles show a small magnetic permeability as magnetic powder.
  • the magnetic powder itself is angular particles by pulverization, the fluidity thereof is too poor for a suitable magnetic material for a bonded magnetic core.
  • a magnetic material suitable for obtaining a bonded magnetic core having a large magnetic permeability was conventionally proposed.
  • mixed ferrite particles consisting of particle groups having different particle sizes of from 100 ⁇ m to 5 mm in diameter, for example, a large-particle group having a diameter of 400 ⁇ m to 5 mm and a small-particle group having a diameter of 100 to 350 ⁇ m are used as a magnetic material for obtaining a molded product (bonded core) having a large initial magnetic permeability.
  • the mixed ferrite particles contain particles having a large diameter such as 5 mm, they are not suitable as a magnetic material for a bonded magnetic core.
  • the magnetic permeability and the fluidity of the ferrite resin composite for producing a bonded magnetic core are mainly dependent on the properties of the ferrite particles which are mixed with base materials of a resin composite.
  • the magnetic permeability of the ferrite resin composite has a tendency to be enlarged with the increase in the magnetic permeability of the ferrite particles mixed.
  • the fluidity of the ferrite resin composite has a tendency to become more excellent as the average particle diameter of the ferrite particles mixed becomes smaller and the surfaces of the particles become smoother.
  • the magnetic permeability of the ferrite particles has a close relation to the average particle diameter and, hence, the magnetic permeability of the ferrite resin composite is enlarged with the increase in the average particle diameter.
  • the fluidity of the ferrite resin composite is deteriorated.
  • the magnetic permeability As to the relationship between the magnetic permeability and the average particle diameter of the ferrite particles obtained by the conventional method, when the average particle diameter is about 100 ⁇ m, the magnetic permeability is about 18, and when the average particle diameter is about 200 ⁇ m, the magnetic permeability is about 23.
  • the ferrite particles mixed are required to have an appropriate average particle diameter which produces a large magnetic permeability and does not obstruct the fluidity, in particular, an average particle diameter of not more than 200 ⁇ m, and to have as smooth a surface as possible.
  • the present inventors have also paid attention to spray drying which is capable of granulation substantially in the form of a sphere.
  • a mixed powder for producing ferrite particles consisting essentially of 47 to 55 mol%, calculated as Fe2O3, of iron oxide or iron oxide hydroxide powder, 10 to 23 mol%, calculated as NiO, of nickel oxide powder and 25 to 40 mol%, calculated as ZnO, of zinc oxide powder into and with water containing 0.2 to 1.0 wt% of a surfactant based on the weight of the mixed powder for producing ferrite particles so as to prepare a water-dispersed slurry having a slurry concentration of 40 to 60 wt%, spray-drying the resultant slurry so as to obtain the granules having an average particle diameter of 25 to 180 ⁇ m, and calcining the obtained granules at a temperature of 1100 to 1350°C, the obtained nickel zinc ferrite spherical particles comprises
  • ferrite particles for a bonded magnetic core comprising crystal grains of 5 to 15 ⁇ m in average diameter, and having an average particle diameter of 20 to 150 ⁇ m and a magnetic permeability of not less than 25.
  • a ferrite resin composite which comprises nickel zinc ferrite spherical particles comprising crystal grains of 5 to 15 ⁇ m in average diameter and having an average particle diameter of 20 to 150 ⁇ m, and base materials of a resin composite and which has a magnetic permeability of not less than 25 and an excellent fluidity.
  • a process for producing ferrite particles for a bonded magnetic core comprising crystal grains of 5 to 15 ⁇ m in average diameter, and having an average particle diameter of 20 to 150 ⁇ m and a magnetic permeability of not less than 25, the process comprising the steps of dispersing and mixing a powder for producing ferrite particles consisting essentially of 47 to 55 mol%, calculated as Fe2O3, of an iron oxide or iron oxide hydroxide powder, 10 to 23 mol%, calculated as NiO, of a nickel oxide powder and 25 to 40 mol%, calculated as ZnO, of an zinc oxide powder as a starting material into and with water containing 0.2 to 1.0 wt% of a surfactant based on the weight of the powder for producing ferrite particles so as to prepare a water-dispersed slurry having a slurry concentration of 40 to 60 wt%, spray-drying the resultant slurry so as to obtain granules having an average particle diameter of 25 to 180 ⁇
  • the nickel zinc ferrite spherical particles as ferrite particles, comprising crystal grains of 5 to 15 ⁇ m in average diameter and having an average particle diameter of 20 to 150 ⁇ m of the present invention are produced by using an iron oxide or iron oxide hydroxide powder, a nickel oxide powder and a zinc oxide powder as starting materials.
  • the nickel zinc ferrite spherical particles are produced by dispersing and mixing a mixed powder for producing ferrite particles of 47 to 55 mol%, preferably 48 to 53 mol%, calculated as Fe2O3, of iron oxide or iron oxide hydroxide, 10 to 23 mol%, preferably 13 to 20 mol%, calculated as NiO, of nickel oxide and 25 to 40 mol%, preferably 27 to 39, calculated as ZnO, of zinc oxide into and with water containing 0.2 to 1.0 wt% of a surfactant based on the weight of the mixed powder for producing ferrite particles so as to prepare a water-dispersed slurry having a slurry concentration of 40 to 60 wt%, spray-drying the resultant slurry so as to obtain the granules having an average particle diameter of 25 to 180 ⁇ m, and calcining the obtained granules at a temperature of 1100 to 1350°C.
  • a mixed powder for producing ferrite particles of 47 to 55 mol%,
  • the reason why the nickel zinc ferrite spherical particles having a magnetic permeability of not less than 25 are obtained according to the present invention is considered to be that the nickel zinc ferrite spherical particles obtained by the process according to the present invention comprises uniform crystal grains of an appropriate size containing few pores.
  • the ferrite particles for a bonded magnetic core according to the present invention are spherical particles having appropriate sizes unlike the irregular, the particles of the present invention have an excellent fluidity which facilitates the production of a molded product having a complicated shape when the ferrite particles are kneaded with a resin and molded, especially, by injection molding.
  • the ferrite particles for a bonded magnetic core according to the present invention comprises ferrite particles having a composition represented by 47 to 55 mol%, preferably 48 to 53 mol% of Fe2O3, 10 to 23 mol%, preferably 13 to 20 mol% of NiO and 25 to 40 mol%, preferably 27 to 39 of ZnO.
  • the particles having a composition other than this ranges are unfavorable for practical use because the magnetic permeability is apt to be lowered.
  • the ferrite particles for a bonded magnetic core according to the present invention comprise nickel zinc ferrite spherical particles having an average diameter of 20 to 150 ⁇ m, preferably 30 to 140 ⁇ m and comprising crystal grains of 5 to 15 ⁇ m, preferably 5 to 13 ⁇ m in average diameter. If the average particle diameter of the ferrite particles is less than 20 ⁇ m, the growth of the particles is unfavorably insufficient. The average particle diameter of more than 150 ⁇ m is also unfavorable because the crystal grains abnormally grow and many pores tend to remain therein, thereby lowering the magnetic permeability.
  • the average particle diameter of the granules before calcination in the range of 20 to 180 ⁇ m.
  • the mixed powder for producing ferrite particles into and with water containing 0.2 to 1.0 wt%, preferably 0.2 to 0.8 wt% of a surfactant based on the weight of the mixed powder for producing ferrite particles, thereby obtaining a water-dispersed slurry having a slurry concentration of 40 to 60 wt%, preferably 40 to 55 wt%, and thereafter to spray-dry the resultant slurry.
  • the slurry concentration is less than 40 wt%, the spray-drying efficiency is lowered, which often leads to the reduction in the productivity.
  • the slurry concentration is more than 60 wt%, it is difficult to supply and spray-dry the slurry and, hence, it is difficult to produce the ferrite particles for a bonded core of the present invention.
  • iron oxide which is one of the starting materials of the present invention
  • ⁇ -Fe2O3, ⁇ -Fe2O3 and Fe3O4 are usable.
  • ion oxide hydroxide ⁇ -­FeOOH, ⁇ -FeOOH and ⁇ -FeOOH are usable.
  • surfactants generally used as a dispersant for a water-dispersed slurry, for example, alkali salts, amine salts and ammonium salts of anionic surfactants, lower fatty acid salts and hydrochlorides of cationic surfactants are usable.
  • the amount of surfactant used is preferably 0.2 to 1.0 wt% based on the weight of the mixed powder for producing ferrite particles in consideration of sphericity of the ferrite particles obtained.
  • the calcining temperature is in the range of 1100 to 1350°C. If the temperature is lower than 1100°C, it is difficult to obtain large crystal grains. If it exceeds 1350°C, the abnormal growth of the crystal grains is accelerated, so that the crystal grains become unfavorably non-uniform and contain many pores.
  • the ferrite resin composite according to the present invention is a mixture of the above-described nickel zinc ferrite spherical particles comprising crystal grains of 5 to 15 ⁇ m in average diameter and having an average particle diameter of 20 to 150 ⁇ m and a resin, and has a magnetic permeability of not less than 25 and an excellent fluidity.
  • the nickel zinc ferrite spherical particles of the present invention may be coated in advance with a coupling agent which is generally used as a surface treating agent, for example, a silane coupling agent, titanium coupling agent, aluminum coupling agent and zircoaluminate coupling agent, or a cationic, anionic or nonionic surfactant in order to enhance various properties such as the dispersibility.
  • a coupling agent which is generally used as a surface treating agent, for example, a silane coupling agent, titanium coupling agent, aluminum coupling agent and zircoaluminate coupling agent, or a cationic, anionic or nonionic surfactant in order to enhance various properties such as the dispersibility.
  • the mixing ratio (wt%) of the nickel zinc ferrite spherical particles to the base materials of a resin composite according to the present invention is 90 to 95/5 to 10, preferably 92 to 9416 to 8 in consideration of the magnetic permeability and the fluidity of the ferrite resin composite.
  • the base materials of a resin composite in the present invention is a resin with a plasticizer, lubricant, antioxidant, etc., added thereto, if necessary.
  • thermoplastic resin such as a polystyrene resin, polyethylene resin, AS resin (acrylonitrile-styrene copolymer), ABS resin (acrylonitrile-butadiene-styrene copolymer), vinyl chloride resin, EVA resin (ethylene-vinylacetate copolymer), PMMA resin (polymethylmethacrylate), polyamide resin, polypropylene resin, EEA resin (ethylene-ethylacrylate copolymer) and PPS resin (polyphenylene sulfide), and a thermosetting resin such as a phenol resin, urea resin, melamine resin, alkyd resin, epoxy resin and polyurethane resin.
  • a thermoplastic resin such as a polystyrene resin, polyethylene resin, AS resin (acrylonitrile-styrene copolymer), ABS resin (acrylonitrile-butadiene-styrene copolymer), vinyl chloride resin, EVA resin (ethylene-vinylacetate cop
  • the ferrite resin composite of the present invention is usable both for compression molding and for injection molding, since the fluidity thereof is excellent, it is preferably used for injection molding.
  • the nickel zinc ferrite spherical particles of the present invention which have an average particle diameter of 20 to 150 ⁇ m and a magnetic permeability of not less than 25, are suitable as ferrite particles for a bonded magnetic core.
  • a ferrite resin composite of the present invention has a large magnetic permeability such as not less than 25 due to the large magnetic permeability of the ferrite particles which are mixed with the base materials of a resin composite, and an excellent fluidity due to the ferrite particles having appropriate size and smooth spherical surfaces.
  • the ferrite resin composite of the present invention is thereof suitable as a ferrite resin composite which is now demanded.
  • the application of the ferrite resin composite of the present invention, which has a large magnetic permeability, to an electromagnetic wave absorber and an electromagnetic wave insulator is expected.
  • a cylindrical molded product having an outer diameter of 36 mm, an inner diameter of 24 mm and a height of 10 mm was produced by the press-molding of the granules of a mixture of ferrite particles and polyvinyl alcohol (M A BOZ O RUT-30 produced by Matsumoto Yushi Seiyaku Co., Ltd.) under a pressure of 1 ton/cm2 as a sample being measured.
  • M A BOZ O RUT-30 produced by Matsumoto Yushi Seiyaku Co., Ltd.
  • the magnetic permeability of the ferrite particles are expressed by the values obtained by measuring the magnetic permeability of the thus-­obtained molded product which has been wound with a winding at 40 turns, by an impedance analyzer 4194A (produced by Yokokawa Hewlet Packard, Ltd.) at a frequency of 1 MHz.
  • the magnetic permeability of the ferrite resin composite of the present invention was measured by the same method described above except for using a molded product having an outer diameter of 36mm, an inner diameter of 24mm and a height of 10mm, and produced by the press-molding of the granules of the ferrite resin composite.
  • the granules obtained were calcined at a temperature of 1320°C for 3 hours to obtain ferrite particles for a bonded magnetic core which was composed of nickel zinc ferrite spherical particles.
  • the magnetic permeability of the ferrite particles for a bonded magnetic core obtained was 32.7. It was confirmed from the observation of the scanning-type electron micrograph shown in Fig. 1 that the ferrite particles were nickel zinc ferrite spherical particles which were composed of crystal grains 12.2 ⁇ m in average diameter and which had an average particle diameter of 80 ⁇ m and few pores.
  • Ferrite particles for a bonded magnetic core were produced in the same way as in Example 1 except for varying the composition of the mixed powder for producing ferrite particles, the kind and the amount of surfactant, the concentration of the mixed slurry for producing ferrite particles, the particle size of the granules and the calcining temperatures.
  • Example 3 Fe3O4 was used as the iron oxide material and in Example 5, polycarboxylic acid sodium salt (Nobcosant K: produced by Sannopco Co., Ltd.) was used as the surfactant.
  • Comparative Example 7 the mixed powder for producing ferrite particles was granulated into granules about 6 mm in diameter by the conventional method without spray-drying, the granules were calcined at a temperature of 1250°C, and the calcined granules were then pulverized to obtain ferrite particles for a bonded magnetic core having a particle diameter of 39 ⁇ m and containing many pores.
  • the thus-obtained kneaded mixture was granulated into granules having an average particle diameter of about 3 mm, and press-molded at a temperature of 75°C and a pressure of 1.5 ton/cm2 to obtain a cylindrical molded product having an outer diameter of 36 mm, an inner diameter of 24 mm and a height of 10 mm. Since the ferrite resin composite filled in all parts of the mold including every corner, the surface of the molded product was smooth and the circumferential portions of the upper surface and the lower surface of the cylinder are formed into complete circles without any chipping and deformation.
  • the magnetic permeability of the molded product was 31.0
  • Ferrite resin composites were produced in the same way as in Example 7 except for varying the kind and the amount of ferrite particles, the kind and amount of additive and the kneading temperature and time.
  • the molded product produced from the ferrite resin composite obtained in any of Examples 8 to 11 had a smooth surface and complete circular circumferential portions of the upper surface and the lower surface of the cylinder without any chipping and deformation like the molded product obtained in Example 7.

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  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Soft Magnetic Materials (AREA)
  • Compounds Of Iron (AREA)
EP19900304167 1989-04-19 1990-04-18 Particules en ferrite et composite ferrite-résine pour noyau magnétique à liant et procédé de leur fabrication Expired - Lifetime EP0394020B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP1101204A JP2743009B2 (ja) 1989-04-19 1989-04-19 ボンド磁心用フェライト粒子粉末及びその製造法
JP101204/89 1989-04-19
JP2050715A JP2893351B2 (ja) 1990-02-28 1990-02-28 フェライト・樹脂複合組成物
JP50715/90 1990-02-28

Publications (3)

Publication Number Publication Date
EP0394020A2 true EP0394020A2 (fr) 1990-10-24
EP0394020A3 EP0394020A3 (fr) 1991-10-09
EP0394020B1 EP0394020B1 (fr) 1994-09-14

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EP19900304167 Expired - Lifetime EP0394020B1 (fr) 1989-04-19 1990-04-18 Particules en ferrite et composite ferrite-résine pour noyau magnétique à liant et procédé de leur fabrication

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EP (1) EP0394020B1 (fr)
DE (1) DE69012398T2 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0542200A1 (fr) * 1991-11-11 1993-05-19 SIEMENS MATSUSHITA COMPONENTS GmbH & CO. KG Matériau magnétique pour noyaux de bobine et procédé de fabrication
WO2000003404A1 (fr) * 1998-07-10 2000-01-20 Epcos Ag Produit magnetisable, son utilisation et son procede de production
EP1014394A1 (fr) * 1997-02-13 2000-06-28 Kureha Kagaku Kogyo Kabushiki Kaisha Materiau composite doux
WO2007111793A2 (fr) * 2006-02-17 2007-10-04 Steward Advanced Materials, Inc. Procédé et appareil de projection à flamme oxygaz à faible vitesse (lvof) pour l'élaboration de produits de ferrite et produits ainsi obtenus
CN113871126A (zh) * 2021-09-26 2021-12-31 安徽智磁新材料科技有限公司 一种磁性海泡石纳米晶磁芯及其制备方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3542319B2 (ja) 2000-07-07 2004-07-14 昭栄化学工業株式会社 単結晶フェライト微粉末

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2254536A1 (fr) * 1973-12-12 1975-07-11 Xerox Corp
US4268430A (en) * 1979-01-31 1981-05-19 Kanegafuchi Kagaku Kogyo Kabushiki Kaisha Ferrite composition having higher initial permeability and process for preparing molding product therefrom
EP0044592A1 (fr) * 1980-07-22 1982-01-27 Koninklijke Philips Electronics N.V. Composant électromagnétique à liant de résine synthétique et procédé pour sa fabrication
US4352717A (en) * 1975-08-12 1982-10-05 Dowa Mining Co., Ltd. Apparatus for production of spherical grain ferrite powder

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2254536A1 (fr) * 1973-12-12 1975-07-11 Xerox Corp
US4352717A (en) * 1975-08-12 1982-10-05 Dowa Mining Co., Ltd. Apparatus for production of spherical grain ferrite powder
US4268430A (en) * 1979-01-31 1981-05-19 Kanegafuchi Kagaku Kogyo Kabushiki Kaisha Ferrite composition having higher initial permeability and process for preparing molding product therefrom
EP0044592A1 (fr) * 1980-07-22 1982-01-27 Koninklijke Philips Electronics N.V. Composant électromagnétique à liant de résine synthétique et procédé pour sa fabrication

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0542200A1 (fr) * 1991-11-11 1993-05-19 SIEMENS MATSUSHITA COMPONENTS GmbH & CO. KG Matériau magnétique pour noyaux de bobine et procédé de fabrication
EP1014394A1 (fr) * 1997-02-13 2000-06-28 Kureha Kagaku Kogyo Kabushiki Kaisha Materiau composite doux
EP1014394A4 (fr) * 1997-02-13 2000-07-19 Kureha Chemical Ind Co Ltd Materiau composite doux
US6338900B1 (en) 1997-02-13 2002-01-15 Kureha Kagaku Kogyo K.K. Soft magnetic composite material
WO2000003404A1 (fr) * 1998-07-10 2000-01-20 Epcos Ag Produit magnetisable, son utilisation et son procede de production
US6696638B2 (en) 1998-07-10 2004-02-24 Epcos Ag Application and production of a magnetic product
US7011764B2 (en) 1998-07-10 2006-03-14 Epcos Ag Method for producing a magnetic device
WO2007111793A2 (fr) * 2006-02-17 2007-10-04 Steward Advanced Materials, Inc. Procédé et appareil de projection à flamme oxygaz à faible vitesse (lvof) pour l'élaboration de produits de ferrite et produits ainsi obtenus
WO2007111793A3 (fr) * 2006-02-17 2007-12-13 Steward Advanced Materials Inc Procédé et appareil de projection à flamme oxygaz à faible vitesse (lvof) pour l'élaboration de produits de ferrite et produits ainsi obtenus
CN113871126A (zh) * 2021-09-26 2021-12-31 安徽智磁新材料科技有限公司 一种磁性海泡石纳米晶磁芯及其制备方法

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Publication number Publication date
DE69012398D1 (de) 1994-10-20
DE69012398T2 (de) 1995-02-02
EP0394020A3 (fr) 1991-10-09
EP0394020B1 (fr) 1994-09-14

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