EP0394020B1 - 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
EP0394020B1
EP0394020B1 EP19900304167 EP90304167A EP0394020B1 EP 0394020 B1 EP0394020 B1 EP 0394020B1 EP 19900304167 EP19900304167 EP 19900304167 EP 90304167 A EP90304167 A EP 90304167A EP 0394020 B1 EP0394020 B1 EP 0394020B1
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Prior art keywords
ferrite
particles
mol
magnetic permeability
ferrite particles
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Expired - Lifetime
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EP19900304167
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German (de)
English (en)
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EP0394020A2 (fr
EP0394020A3 (fr
Inventor
Shigehisa Yamamoto
Masaru Kawabata
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Toda Kogyo Corp
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Toda Kogyo Corp
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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
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Publication of EP0394020B1 publication Critical patent/EP0394020B1/fr
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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 spherical 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 as a magnetic core material of a transformer.
  • 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 cores having a complicated shape is easy.
  • 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 which is 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, have a closer relation to and are 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 excellent fluidity.
  • the crystal grains grow as large as several hundred ⁇ m and become non-uniform.
  • the crystal grains contain many pores. Due to the non-uniform crystal grains and the presence of many pores, the magnetic permeability is lowered. As a result the obtained ferrite particles have a small magnetic permeability as a magnetic powder.
  • the magnetic powder itself is in the form of angular particles due to the 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 has been 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 ideally suitable as a magnetic material for a bonded magnetic core.
  • US-A-4,357,717 discloses spherical ferrite particles for use as a carrier in a dry process copying machine which have a particle diameter of, for example, 30 to 200 ⁇ m.
  • EP-A-44,592 discloses pre-shaped ferrite bodies for use in the manufacture of electromagnetic components. These may be in the form of balls having a diameter of 0.6 to 1.2 mm.
  • 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 the base materials of a resin composite.
  • the magnetic permeability of the ferrite resin composite has a tendency to increase with the increase in the magnetic permeability of the ferrite particles mixed.
  • the fluidity of the ferrite resin composite has a tendency to become better 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 increases 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 obtained nickel zinc ferrite spherical particles comprise crystal grains of 5 to 15 ⁇ m average diameter, and have an average particle diameter of 20 to 150
  • the present invention provides spherical ferrite particles suitable for a bonded magnetic core, which particles comprise uniform crystal grains of from 5 to 15 ⁇ m in average diameter and have an average particle diameter of from 20 to 150 ⁇ m and a magnetic permeability of not less than 25; the above magnetic permeability being the magnetic permeability of a molded product obtained by:
  • the present invention also provides a ferrite resin composite comprising ferrite particles as defined above and a base resin, said ferrite resin composite having a magnetic permeability of not less than 25; the above magnetic permeability being determined by:
  • the present invention also provides a process for producing ferrite particles as defined above, which comprises:
  • Figs. 1 to 6 are scanning electron micrographs (x 6500), in which
  • the nickel zinc ferrite spherical particles of the present invention are produced from (a) an iron oxide or iron oxide hydroxide powder, (b) a nickel oxide powder and (c) a zinc oxide powder as starting materials. More specifically, the nickel zinc ferrite spherical particles are produced by (i) dispersing and mixing a mixed powder for producing ferrite particles of (a) 47 to 55 mol%, preferably 48 to 53 mol%, calculated as Fe2O3, of an iron oxide or iron oxide hydroxide, (b) 10 to 23 mol%, preferably 13 to 20 mol%, calculated as NiO, of a nickel oxide and (c) 25 to 40 mol%, preferably 27 to 39, calculated as ZnO, of a zinc oxide into and with (d) water containing 0.2 to 1.0 wt% of a surfactant based on the weight of the mixed powder to prepare a water-dispersed slurry having a slurry concentration of 40 to 60 wt%, (ii) spray-drying 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 because they comprise uniform crystal grains of an appropriate size containing few pores.
  • the ferrite particles of the present invention are spherical, have appropriate sizes, and are not irregular, they 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 spherical ferrite particles of the present invention comprise 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 mol%, of ZnO. Particles having a composition outside the above ranges are unfavorable for practical use because the magnetic permeability is apt to be lowered.
  • the spherical ferrite particles of the present invention are nickel zinc ferrite particles having an average diameter of 20 to 150 ⁇ m, preferably 30 to 140 ⁇ m, and comprise crystal grains of 5 to 15 ⁇ m, preferably 5 to 13 ⁇ m, average diameter. If the average particle diameter of the ferrite particles is less than 20 ⁇ m, the growth of the particles is unfavorably insufficient. An average particle diameter of more than 150 ⁇ m is also unfavorable because the crystal grains grow abnormally and many pores tend to remain therein, thereby lowering the magnetic permeability.
  • the average particle diameter of the granules before calcination is necessary to control the average particle diameter of the granules before calcination to from 25 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. If the slurry concentration is less than 40 wt%, the spray-drying efficiency is lowered, which often leads to a reduction in productivity. If 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 of the present invention.
  • iron oxide which is one of the starting materials of the present invention
  • ⁇ -Fe2O3, ⁇ -Fe2O3 and Fe3O4 are usable.
  • iron 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 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 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, 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 of the present invention is a mixture of the above-described nickel zinc ferrite spherical particles 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 94/6 to 8 in consideration of the magnetic permeability and the fluidity of the ferrite resin composite.
  • the base material of the resin composite in the present invention is a resin with a plasticizer, lubricant, antioxidant, for example, 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 are suitable as ferrite particles for a bonded magnetic core.
  • the ferrite resin composite of the present invention has a large magnetic permeability of not less than 25 due to the large magnetic permeability of the ferrite particles which are mixed with the base material of a resin composite, and an excellent fluidity due to the ferrite particles having appropriate sizes and smooth spherical surfaces.
  • the ferrite resin composite of the present invention is therefore suitable as a ferrite resin composite which is now demanded.
  • 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 press-molding of granules of a mixture of ferrite particles and polyvinyl alcohol (M ⁇ BOZ ⁇ RU T-30 produced by Matsumoto Yushi Seiyaku Co., Ltd.) under a pressure of 1 ton/cm2 as a sample being measured.
  • M ⁇ BOZ ⁇ RU T-30 produced by Matsumoto Yushi Seiyaku Co., Ltd.
  • the magnetic permeabilities 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 of 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 spherical nickel zinc ferrite particles for a bonded magnetic core.
  • the magnetic permeability of the ferrite particles 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 of 12.2 ⁇ m 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 5 mm in diameter by a 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 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 were 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)

Claims (9)

  1. Particules de ferrite sphériques utilisables pour un noyau magnétique aggloméré, ces particules comprenant des grains cristallins uniformes de 5 à 15 µm de diamètre moyen et ayant un diamètre moyen de particule de 20 à 150 µm et une perméabilité magnétique non inférieure à 25 ;
       la perméabilité magnétique ci-dessus étant la perméabilité magnétique d'un produit moulé obtenu par :
    a) moulage par compression des particules et d'alcool polyvinylique sous une pression d'une tonne/cm² pour former un produit moulé cylindrique ayant un diamètre externe de 36 mm, un diamètre interne de 24 mm et une hauteur de 10 mm ; et
    b) formation autour du produit moulé d'un enroulement de 40 tours et mesure de la perméabilité magnétique de celui-ci avec un analyseur d'impédance à une fréquence de 1 MHz.
  2. Particules de ferrite selon la revendication 1, qui comprennent de 48 à 53 moles % de Fe₂O₃, de 13 à 20 moles % de NiO et de 27 à 39 moles % de ZnO.
  3. Composite ferrite-résine comprenant des particules de ferrite selon les revendications 1 ou 2 et une résine de base, ce compcsite ferrite-résine ayant une perméabilité magnétique non inférieure à 25 ;
       la perméabilité magnétique ci-dessus étant déterminée par :
    a) moulage par compression de granulés de ce composite ferrite-résine sous une pression d'une tonne/cm² pour former un produit moulé cylindrique ayant un diamètre externe de 36 mm, un diamètre interne de 24 mm et une hauteur de 10 mm ; et
    b) formation autour du produit moulé d'un enroulement de 40 tours et mesure de la perméabilité magnétique de celui-ci avec un analyseur d'impédance à une fréquence de 1 MHz.
  4. Composite selon la revendication 3, qui comprend de 92 à 94 % en poids des particules et de 8 à 6 % en poids de la résine de base.
  5. Composite selon les revendications 3 ou 4 sous la forme d'un noyau magnétique.
  6. Procédé de préparation de particules de ferrite selon les revendications 1 ou 2, qui comprend :
    (i) le mélange a) de 47 à 55 moles %, calculées en Fe₂O₃, d'une poudre d'oxyde de fer ou d'hydroxyde de fer, b) de 10 à 23 moles %, calculées en NiO, d'une poudre d'oxyde de nickel et c) de 25 à 40 moles %, calculées en ZnO, d'une poudre d'oxyde de zinc et d) de l'eau contenant de 0,2 à 1,0 % en poids d'un agent tensioactif par rapport au poids total des poudres a), b) et c), de manière à préparer une bouillie ayant une concentration de 40 à 60 % en poids
    (ii) séchage par pulvérisation de la bouillie obtenue de manière à obtenir des granulés sphériques ayant un diamètre moyen de particule de 25 à 180 µm et
    (iii) calcination des granulés obtenus à une température de 1100 à 1350 °C.
  7. Procédé selon la revendication 6, dans lequel le stade (i) comprend le mélange :
    a) de 48 à 53 moles % de Fe₂O₃
    b) de 13 à 20 moles % de NiO
    c) de 27 à 39 moles % de ZnO
    d) d'eau contenant 0,2 à 0,8 % en poids d'un agent tensioactif.
  8. Procédé selon les revendications 6 ou 7, dans lequel l'agent tensioactif du stade (i) est un sel de métal alcalin, un sel d'amine, un sel d'ammonium d'un agent tensioactif anionique, un sel d'acide gras ou un chlorhydrate d'un agent tensioactif cationique.
  9. Procédé selon l'une quelconque des revendications 6 à 8, qui comprend le stade supplémentaire de malaxage de particules de ferrite avec la résine de base et de moulage par compression du mélange pour former un produit moulé.
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 EP0394020A2 (fr) 1990-10-24
EP0394020A3 EP0394020A3 (fr) 1991-10-09
EP0394020B1 true EP0394020B1 (fr) 1994-09-14

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DE (1) DE69012398T2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6793842B2 (en) 2000-07-07 2004-09-21 Shoei Chemical Inc. Single-crystal ferrite fine powder

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE59209285D1 (de) * 1991-11-11 1998-05-20 Siemens Matsushita Components Verwendung eines magnetischen Materials als Spulenkern
JP3838730B2 (ja) * 1997-02-13 2006-10-25 株式会社メイト 軟磁性複合材料
EP1097463B1 (fr) 1998-07-10 2002-11-27 Epcos Ag Produit magnetisable, son utilisation et son procede de production
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
CN113871126B (zh) * 2021-09-26 2024-07-30 阜阳师范大学 一种磁性海泡石纳米晶磁芯及其制备方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1054837A (fr) * 1973-12-12 1979-05-22 Xerox Corporation Formation particulaire spherique non alveolaire pour ferrites frittees
JPS5224200A (en) * 1975-08-12 1977-02-23 Dowa Mining Co Ltd Method for production of spherical ferrite powder
JPS55103705A (en) * 1979-01-31 1980-08-08 Kanegafuchi Chem Ind Co Ltd Ferrite composition with high initial permeability and method of manufacturing its compact
NL8004200A (nl) * 1980-07-22 1982-02-16 Philips Nv Kunststofgebonden electromagnetische component en werkwijze voor het vervaardigen daarvan.

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6793842B2 (en) 2000-07-07 2004-09-21 Shoei Chemical Inc. Single-crystal ferrite fine powder

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EP0394020A2 (fr) 1990-10-24
EP0394020A3 (fr) 1991-10-09
DE69012398T2 (de) 1995-02-02
DE69012398D1 (de) 1994-10-20

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