EP0383035B1 - Magnetkerne aus Eisen-Silizium-Legierungspulver und Herstellungsverfahren - Google Patents

Magnetkerne aus Eisen-Silizium-Legierungspulver und Herstellungsverfahren Download PDF

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Publication number
EP0383035B1
EP0383035B1 EP19900100930 EP90100930A EP0383035B1 EP 0383035 B1 EP0383035 B1 EP 0383035B1 EP 19900100930 EP19900100930 EP 19900100930 EP 90100930 A EP90100930 A EP 90100930A EP 0383035 B1 EP0383035 B1 EP 0383035B1
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EP
European Patent Office
Prior art keywords
powder
alloy powder
cores
permeability
core
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.)
Revoked
Application number
EP19900100930
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English (en)
French (fr)
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EP0383035A2 (de
EP0383035A3 (de
Inventor
Tokuhiko C/O Nippon Steel Corporation Nishida
Masao C/O Nippon Steel Corporation Yamamiya
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Nippon Steel Corp
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Nippon Steel Corp
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Application filed by Nippon Steel Corp filed Critical Nippon Steel Corp
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Publication of EP0383035A3 publication Critical patent/EP0383035A3/de
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0206Manufacturing of magnetic cores by mechanical means
    • H01F41/0246Manufacturing of magnetic circuits by moulding or by pressing powder
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12Magnets 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
    • H01F1/14Magnets 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 metals or alloys
    • H01F1/147Alloys characterised by their composition
    • H01F1/14766Fe-Si based alloys
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12Magnets 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
    • H01F1/14Magnets 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 metals or alloys
    • H01F1/20Magnets 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 metals or alloys in the form of particles, e.g. powder
    • H01F1/22Magnets 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 metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H01F1/24Magnets 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 metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated

Definitions

  • This invention relates to a process of manufacturing iron-silicon alloy powder magnetic cores used in noise filters and choke coils for switching power supplies and powder cores obtainable by such process.
  • the prior art includes the following process for manufacturing materials for powder magnetic cores used in magnetic noise suppression and choke coils. Specifically, the process is as follows: magnetic metal powders including pure iron, carbonyl iron, Fe-Ni alloy (hereafter referred to as Permalloy), or Fe-Si-Al alloy (hereafter referred to as Sendust) to which insulating binders such as sodium silicate or epoxy resin are added are compacted under pressure of 1-15 ton/cm2 and then heat-treated to relieve compression stresses (Japan Society of Powder and Powder Metallurgy, Magnetic Materials (1970), The Nikkan Kogyo Shimbun, Ltd.).
  • magnetic metal powders including pure iron, carbonyl iron, Fe-Ni alloy (hereafter referred to as Permalloy), or Fe-Si-Al alloy (hereafter referred to as Sendust) to which insulating binders such as sodium silicate or epoxy resin are added are compacted under pressure of 1-15 ton/cm2 and then
  • JP-A-60-74602 discloses a dust core which is press-formed from metal magnetic powder obtained by using a water atomization method.
  • EP-A-0 088 992 discloses a method for manufacturing an object of soft-magnetic material by bonding together a mass of powder grains. These grains of iron and iron alloy powders have a particle size of 50 to 1000 ⁇ m and are coated with oxides of Fe, Si, Al and/or the like to a coating thickness of 0.01 to 0.5 ⁇ m, and are then subjected to isostatic pressing at a temperature of 600 to 900°C.
  • Pure iron powder cores are used in choke coils for switching power supplies at frequencies of 50 kHz or lower, transformers for ringing-choke-type power supply circuits, and noise suppressors in circuits in which low-frequency currents are superimposed.
  • Permalloy powder cores are used as cores for secondary-side smoothing chokes in switching power supplies in the frequency range of 100-150 kHz, and as noise-suppressors.
  • Sendust powder cores can be used in the same frequency range as permalloy powder cores.
  • powder cores of high permeability and low core loss are increasingly required.
  • the powder particles are insulated by epoxy resin or sodium silicate to avoid direct contact between powder particles and decrease eddy current losses in the high-frequency region.
  • pressing is used to increase density and obtain high permeability and low core loss.
  • Permalloy powder cores have higher permeability than pure iron powder cores and their high-frequency magnetic properties are excellent, but they are expensive and the adhesion of powder to the insulating layer is insufficient so that the insulation between particles breaks down, markedly degrading the magnetic properties in the high frequency region.
  • an object of the present invention is to solve these problems by providing a process of manufacturing Fe-Si alloy powder cores and powder cores obtainable by such process which are inexpensive which have high permeability, excellent magnetic properties in the high frequency region and low core loss.
  • Figure 1 shows the variation of permeability with the frequency for powder cores of this invention along with other powder cores for comparison.
  • the inventors studied the effects on magnetic characteristics of interlayer insulation, powder compacting, powder composition and other factors which affect the magnetic properties in the high frequency region. As a result of this research, they found that Fe-Si alloy powders produced by water atomization form a stable oxide layer on the surface of the particles and have excellent compressibility, so that they may be manufactured into powder cores of high permeability and low core loss.
  • the invention is an Fe-Si alloy powder core manufactured by compacting an alloy powder of an average particle diameter of 10-100 ⁇ m, produced by water atomization, in which the composition by weight of the alloy powder is 2-12% silicon, 0.05-0.95% oxygen and the balance being essentially iron.
  • the composition by weight of the alloy powder is 2-12% silicon, 0.05-0.95% oxygen, with an Al, Cr and Ti content of less than 3% separately or combined, and the balance being essentially iron.
  • Fe-Si alloy powder cores comprising the steps of adding an insulating binder to alloy powder of the above composition, compacting the resulting mixture and curing.
  • the Si in the composition of the alloy powder of the invention is an essential component of this alloy, and if the Si content is less than 2%, electrical resistance will be decreased and eddy current losses in the high-frequency region will increase so that the desired permeability will not be obtained. If the Si content exceeds 12%, an intermetallic compound will be formed, making the powder hard and thus losing compressibility.
  • the Si content is preferably between 3.0% and 7.5%, resulting in low magnetic anisotropy and magnetostriction.
  • Oxygen is vital to the formation of an insulating film on the surface of the powder, so if the oxygen content is less than 0.05%, a stable oxide layer will not be formed, and if greater than 0.95%, the oxide layer will become too thick, decreasing permeability and also decreasing the density of the green compacts. Therefore the oxygen content is in the range of 0.05-0.95%.
  • the Al, Cr and Ti added to the essential components as optional components have the effect of further enhancing the stability of the insulating layer formed. If any of the elements are added individually or together in an amount exceeding 3%, the film will grow too thick, and the compressibility of the powder will be lowered, hence the 3% limitation.
  • the particle size of the powder greatly affects permeability and the quality of interparticle insulation. If the average particle size is less than 10 ⁇ m, the magnetic properties of the powder itself will be impaired, and a high packing density cannot be obtained so the desired level of permeability will not be attained. On the other hand, if the particle size exceeds 100 ⁇ m, excessive friction between particles will damage the insulating layer, so the magnetic properties in the high-frequency region will be impaired, hence the range of 10-100 ⁇ m.
  • Water atomization is a process of producing metal powder in which the raw material is melted and this molten metal is dropped through a tundish nozzle as a downward stream of molten metal of 2-20 mm in diameter. Water of high pressure, 50-800 kg/cm2, is sprayed from an atomizing nozzle system onto this metal stream, which is disintegrated into fine droplets which solidify as powder (Metals Handbook Vol. 7, Page 25).
  • the water atomizing is easily controllable to obtain powder of the desired composition.
  • the particles are irregular in shape, giving the powder excellent compressibility and a low demagnetization factor.
  • the metal since the metal is oxidized by the water, the thickness of the oxide layer, and hence the oxygen content of the alloy powder, may be controlled by altering the atmosphere during atomization or altering the dissolved oxygen content of the water.
  • powder suited to the powder core of the invention may be produced.
  • an atomizing nozzle is provided on the inside top of an atomizing chamber. Molten metal is dropped as a fine stream from the top of the chamber and atomized as high-pressure water from the nozzle strikes the metal stream.
  • the amount of oxygen of the powder will reach a level of 3-5%. If the chamber atmosphere is replaced by nitrogen, argon or another inert gas and the inside of the chamber is filled with water to rapidly quench the drops of atomized metal, the oxygen content of the iron powder can be decreased to about 1%.
  • the oxygen content of the iron powder can be decreased to less than 0.1%.
  • the dissolved oxygen content of the water can be altered to control the oxygen content of the powder within the range of 0.05-0.95%.
  • Water-atomized Fe-Si alloy powder produced in this manner will have an average particle size of 10-100 ⁇ m after sieving.
  • An insulating binder typically sodium silicate, epoxy resin or, if heat treatment will be carried out, a heat-resistant resin such as silicone resin will be added in the amount of 1-10% by weight and mixed.
  • compacting under a pressure of 1-15 ton/cm2 will be used to make compacts of the desired shape, and then hardening treatment and, if necessary, heat treatment will be carried out. Finally, an insulating coating is painted onto the surface and the powder core is manufactured.
  • the compacts After adding insulating binder to Fe-Si alloy particles and compacting, the compacts are hardened by a hardening treatment in which they are heated to 100-300°C, depending on the type of insulating binder and the application for the powder core.
  • a hardening treatment in which they are heated to 100-300°C, depending on the type of insulating binder and the application for the powder core.
  • the curing step may be omitted.
  • Fe-Si alloy powder can be used in this manner to manufacture powder cores having excellent electromagnetic properties, the electromagnetic properties may be further improved by heat-treating the compacted cores.
  • Heat treatment is effective when carried out at a temperature between 500°C and 950°C in an inert atmosphere of nitrogen or argon.
  • nitrogen or argon atmosphere is preferable.
  • the relief of compacting stress is difficult at less than 500°C, while if 950°C is exceeded, the insulating layer breaks down and the powder particles are sintered together and the magnetic properties in the high-frequency region deteriorate.
  • heat treatment at a temperature between 500°C and 950°C relieves stress in the core and causes the structure to change to improve electromagnetic properties by forming a superlattice structure.
  • the time should generally be longer at lower temperature and shorter at high temperature, but nevertheless it should be 1-20 hours, preferably 1-5 hours.
  • Fe-Si alloy powders of various compositions as listed in Table 1 were fabricated and sieved to the desired average particle size.
  • the oxygen content of the alloy powder was altered by using Ar gas as the atomizing atmosphere and by bubbling Ar gas through the cooling water and atomizing water.
  • sodium silicate was added to the Fe-Si alloy powder in an amount of 1.0% by weight, and the mixture was pressed at a pressure of 8 ton/cm2.
  • the heat treatment was carried out in an argon atmosphere.
  • the notation ⁇ e10K indicates the permeability at a frequency of 10 kHz
  • ⁇ e10M/ ⁇ e10K indicates the ratio of permeability at 10 MHz to permeability at 10 kHz, and this is taken as an indication of the magnetic properties in the high-frequency region.
  • the oxygen content of cores 1-9 of the invention is in the range 0.05-0.95%, the average particle size is in the range 10-100 ⁇ m and each core exhibits high permeability at 10 kHz of 70 or greater.
  • the high-frequency properties in that the permeability at 10 MHz is the same or greater than the permeability at 10 kHz.
  • the cores of the invention which had been heat treated, namely cores 8-13, maintained a high permeability even up to the high-frequency region.
  • the Sendust powder core 4 the pure iron powder core 5 and the Permalloy powder core 6 each have a higher permeability at 10 kHz than cores 1-5 of the invention, but a lower permeability at 10 MHz, so their high-frequency properties are inferior.
  • core 1 for comparison is made from powder of such small particle size that the magnetism of the powder itself is poor, while the particle size of core 2 for comparison is so large that the insulating performance is inferior in the high-frequency range.
  • the powder In core 3 for comparison, in which the Si content exceeds 12%, the powder is so hard that the packing density is insufficient and the permeability at 10 kHz is low.
  • core 7 for comparison the gas atomization by which the powder was produced caused the particles to be spherically-shaped and thus the demagnetization factor is high and the permeability low.
  • Core 8 for comparison has a thick oxide layer so its permeability is low.
  • Core 9 for comparison was subjected to high-temperature annealing, so the powder became sintered, thus increasing permeability in the low-frequency range but giving inferior properties in high-frequency region.
  • Core 10 for comparison is made from carbonyl iron powder so while the high-frequency properties is good, the absolute value of the permeability is low.
  • Figure 1 shows the variation of permeability with frequency for several cores in Table 1 fabricated by the same steps as above.
  • the cores on the graph are cores 2 and 8 of the invention and cores 4, 5 and 10 for comparison.
  • Core 2 of the invention exhibits high permeability even at frequencies above 10 MHz, while the permeability of the cores for comparison begins to drop off at around 1 MHz.
  • the cores of the invention have good high-frequency magnetic properties.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Manufacturing & Machinery (AREA)
  • Powder Metallurgy (AREA)
  • Soft Magnetic Materials (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)

Claims (3)

  1. Verfahren zur Herstellung eines Kerns aus Fe-Si-Legierungspulver mit den folgenden Schritten:
    a) Herstellen eines Legierungspulvers mit 2 bis 12 Gew.-% Si, 0,05 bis 0,95 Gew.-% O und wahlweise weniger als 3 Gew.-% Al, Cr und/oder Ti, wobei der Rest Eisen ist, durch Wasserverdüsung, bei der ein Metallschmelzstrom in einen Verdüsungsbehälter gegossen und mit Wasser unter hohem Druck zum Verdüsen des Metallstroms besprüht wird, um unregelmäßig geformte Legierungspulverteilchen mit einer durchschnittlichen Teilchengröße von 10 bis 100 µm zu erhalten, wobei die Atmosphäre des Verdüsungsbehälters und/oder der Gelöstsauerstoffgehalt des unter hohem Druck stehenden Wassers zum Steuern des Sauerstoffgehalts des Legierungspulvers eingestellt wird,
    b) Zufügen eines Isolierbindemittels zu dem Legierungspulver,
    c) Formen der resultierenden Mischung und
    d) Durchführen einer Härtungsbehandlung der geformten Mischung.
  2. Verfahren nach Anspruch 1, wobei die geformte Mischung einer Wärmebehandlung in einer Inertatmosphäre bei einer Temperatur im Bereich von 500 bis 950 °C unterzogen wird.
  3. Kern aus Fe-Si-Legierungspulver, der durch ein Verfahren gemäß Anspruch 1 oder 2 erhältlich ist.
EP19900100930 1989-01-18 1990-01-17 Magnetkerne aus Eisen-Silizium-Legierungspulver und Herstellungsverfahren Revoked EP0383035B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP7853/89 1989-01-18
JP785389 1989-01-18
JP1335899A JPH0682577B2 (ja) 1989-01-18 1989-12-25 Fe―Si系合金圧粉磁心およびその製造方法
JP335899/89 1989-12-25

Publications (3)

Publication Number Publication Date
EP0383035A2 EP0383035A2 (de) 1990-08-22
EP0383035A3 EP0383035A3 (de) 1991-07-03
EP0383035B1 true EP0383035B1 (de) 1995-10-04

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EP19900100930 Revoked EP0383035B1 (de) 1989-01-18 1990-01-17 Magnetkerne aus Eisen-Silizium-Legierungspulver und Herstellungsverfahren

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EP (1) EP0383035B1 (de)
JP (1) JPH0682577B2 (de)
DE (1) DE69022751T2 (de)

Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19610196A1 (de) * 1996-03-15 1997-09-18 Horst Dr Kleine Verfahren zur Herstellung von weichmagnetischen FeSi-Massekernen
JP2000040614A (ja) * 1998-05-18 2000-02-08 Daido Steel Co Ltd ノイズフィルタ―用コア材
KR100533097B1 (ko) 2000-04-27 2005-12-02 티디케이가부시기가이샤 복합자성재료와 이것을 이용한 자성성형재료, 압분 자성분말성형재료, 자성도료, 복합 유전체재료와 이것을이용한 성형재료, 압분성형 분말재료, 도료, 프리프레그및 기판, 전자부품
US6395193B1 (en) * 2000-05-03 2002-05-28 Lord Corporation Magnetorheological compositions
US6621399B2 (en) 2002-01-17 2003-09-16 Nec Tokin Corporation Powder core and high-frequency reactor using the same
US6788185B2 (en) 2002-01-17 2004-09-07 Nec Tokin Corporation Powder core and high-frequency reactor using the same
US6646532B2 (en) 2002-02-26 2003-11-11 Nec Tokin Corporation Powder core and reactor using the same
EP1341191A1 (de) * 2002-02-27 2003-09-03 NEC TOKIN Corporation Puderkern und Reaktor damit
KR20040042214A (ko) * 2002-11-13 2004-05-20 휴먼일렉스(주) Fe-Si 합금분말을 이용한 SMD 코아 제조방법
JP2009088502A (ja) * 2007-09-12 2009-04-23 Seiko Epson Corp 酸化物被覆軟磁性粉末の製造方法、酸化物被覆軟磁性粉末、圧粉磁心および磁性素子
JP5257743B2 (ja) * 2008-02-28 2013-08-07 日立金属株式会社 Fe基軟磁性粉末、その製造方法、および圧粉磁心
JP2010080978A (ja) * 2009-12-16 2010-04-08 Daido Steel Co Ltd 軟磁性合金粉末および圧粉磁芯
KR101881952B1 (ko) * 2010-06-09 2018-07-26 신토고교 가부시키가이샤 철족계 연자성 분말재
CN103065786A (zh) * 2011-10-22 2013-04-24 湖南康力新材料科技有限责任公司 一种高磁导率低功耗铁硅铝磁粉芯的制造方法
JP5650702B2 (ja) * 2012-10-15 2015-01-07 株式会社タムラ製作所 圧粉磁心とその製造方法
JP6382487B2 (ja) * 2013-01-24 2018-08-29 Tdk株式会社 磁芯およびコイル型電子部品
KR102047565B1 (ko) * 2014-11-04 2019-11-21 삼성전기주식회사 인덕터

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58147106A (ja) * 1982-02-26 1983-09-01 Toshiba Corp 鉄心材料
SE8201678L (sv) * 1982-03-17 1983-09-18 Asea Ab Sett att framstella foremal av mjukmagnetiskt material
US4564401A (en) * 1983-09-29 1986-01-14 Crucible Materials Corporation Method for producing iron-silicon alloy articles
JPS6074603A (ja) * 1983-09-30 1985-04-26 Nippon Ferrite Ltd 圧粉磁心
JPS6074602A (ja) * 1983-09-30 1985-04-26 Nippon Ferrite Ltd 圧粉磁心

Also Published As

Publication number Publication date
JPH0682577B2 (ja) 1994-10-19
EP0383035A2 (de) 1990-08-22
EP0383035A3 (de) 1991-07-03
DE69022751T2 (de) 1996-04-04
JPH02290002A (ja) 1990-11-29
DE69022751D1 (de) 1995-11-09

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