JP2006077294A - Composite magnetic material and magnetic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite magnetic material and a magnetic part obtained by compression-forming the above material with which a frequency characteristic is not deteriorated even with a heat treatment. <P>SOLUTION: The composite magnetic material is obtained by lamination interposing the covered layer (C1) composed of an oxide magnetic material (c1) between a covered layer (A) composed of a material (a) and a material (b) in powder of the grains of a metallic magnetic material (b), and either requirement of the following (1) and (2), is satisfied. (1) Equilibrium dissociation pressure in the heat treatment temperature of the high resistant oxide magnetic material (a) is a value at not higher than the equilibrium dissociation pressure in the heat treatment temperature of oxide with one oxidation state higher than the oxide magnetic material (c1). (2) The oxide magnetic material (c1) is in the highest oxidation state which can be taken in the heat treatment temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a composite magnetic material and a magnetic component used for a transformer or a reactor mounted on a switching power supply or the like.

  In recent years, various electronic devices have been reduced in size and weight, and there has been a demand for lower power consumption. Accordingly, there is an increasing demand for a small switching power supply as a power supply mounted on an electronic device. In particular, switching power supplies used for small portable devices such as notebook computers and mobile phones, thin CRTs, and flat panel displays for televisions are strongly required to be small and thin.

  However, in conventional switching power supplies, magnetic components such as transformers and reactors, which are the main components, occupy a large volume. Unless the volume of these magnetic parts is reduced, switching power supplies can be made smaller and thinner. It was difficult.

  Conventionally, metal magnetic materials such as Sendust and Permalloy and oxide magnetic materials such as ferrite have been used for magnetic parts such as transformers and reactors used in such switching power supplies. Metallic magnetic materials generally have a high saturation magnetic flux density and magnetic permeability, but have low electrical resistivity, so that eddy current loss is particularly large in the high frequency region. In recent years, magnetic components tend to be miniaturized by reducing the required inductance value by driving the power supply circuit at a high frequency, but metal magnetic materials cannot be used at a high frequency due to the influence of eddy current loss. On the other hand, an oxide magnetic material has a higher electrical resistivity than a metal magnetic material, and hence eddy current loss that occurs even in a high frequency region is small. However, since the saturation magnetic flux density is small, the volume cannot be reduced. That is, in any case, the volume of the magnetic material is the largest factor determining the inductance value, and it has been difficult to reduce the size and thickness unless the magnetic properties of the magnetic material itself are improved.

  As described above, the conventional magnetic parts have a limit in miniaturization, and cannot fully meet the demand for miniaturization and thinning of electronic devices.

However, recently, as a magnetic material having the advantages of both metal magnetic material and oxide magnetic material, a film of oxide magnetic material with high electrical resistivity is formed on the surface of metal magnetic material with high saturation magnetic flux density and high magnetic permeability. Magnetic materials have been proposed. For example, a high-permeability material in which a high-permeability metal oxide film is formed on the surface of a metal magnetic material powder has been proposed (see Patent Document 1). Further, the surface of the metallic magnetic material consisting of 1~10μm particles coated with _M-Fe x _{O 4} (where M = Ni, Mn, Zn, x ≦ 2) metal oxide magnetic material of the spinel composition represented by A high-density sintered magnetic body is proposed (see Patent Document 2). Further, a ferromagnetic fine particle powder of a metal or intermetallic compound whose surface is coated with a ferrite layer is compression-molded to form a magnetic path between the particles of the ferroelectric particle powder through the ferrite layer. A composite magnetic material characterized by this has been proposed (see Patent Document 3). According to this, the ferrite ultrafine particle powder is mixed with the ferromagnetic fine particle powder of the metal or intermetallic compound whose surface is covered with the ferrite layer and is compression-molded to form a composite (see Patent Document, Claim). Item 7). Further, as an embodiment of the invention, metal or intermetallic ferromagnetic fine particles coated with a ferrite layer on the surface are blended with a particle size distribution, and small particles are formed in the gaps between particles formed by filling large particles. A structure in which the filling rate of particles is increased by burying sequentially is schematically shown.

JP-A-53-91397 JP-A-56-38402 International Publication No. 03 / 015,109 Pamphlet Corrosion and Corrosion Protection Association, “High-temperature oxidation and high-temperature corrosion of metal materials”, Maruzen, July 1982, p.21 or less (2 High-temperature oxidation of metals)

  The magnetic permeability of a composite magnetic material produced by compression molding metal magnetic particles coated with a high-resistance oxide magnetic material such as ferrite is greatly improved by heat treatment, but the frequency characteristics are deteriorated. This is because the high resistivity of the high resistance oxide magnetic material is lowered by the heat treatment. The main cause of the decrease in resistivity is that iron (Fe) contained in the metal magnetic particles is diffused into the high-resistance oxide magnetic material by the heat treatment, and the decrease in resistivity due to reduction of the high-resistance oxide magnetic material, and This is because Fe oxide having a lower resistivity is generated.

  Accordingly, an object of the present invention is to provide a composite magnetic material whose frequency characteristics are not deteriorated even by heat treatment and a magnetic component obtained by compression molding the composite magnetic material.

The composite magnetic material of the present invention comprises a coating layer (A) composed of a material (a) and a material (b) in a powder in which particles of a metal magnetic material (b) are coated with a high resistance oxide magnetic material (a). A laminated composite magnetic material in which a coating layer (C1) made of an oxide magnetic material (c1) is interposed between particles, and satisfies any of the following requirements (1) and (2) It is characterized by.
(1) A value equal to or lower than the equilibrium dissociation pressure at the heat treatment temperature of the oxide having a higher oxidation state than that of the oxide magnetic material (c1). Be.
(2) The oxide magnetic material (c1) is in the highest oxidation state that can be taken at the heat treatment temperature.

  In addition, the composite magnetic material of the present invention comprises a coating layer (A) made of a material (a) and a material (b) in a powder in which particles of a metal magnetic material (b) are coated with a high resistance oxide magnetic material (a). ) Between the particles of the oxide magnetic material (c1) and the laminated composite magnetic material, which is 200 from the heat treatment temperature of the high resistance oxide magnetic material (a). Requirement that the equilibrium dissociation pressure at a temperature higher by 1 ° C. is not more than 100 times the equilibrium dissociation pressure at a temperature higher by 200 ° C. than the heat treatment temperature of the oxide having one higher oxidation state than the oxide magnetic material (c1). (8) is satisfied.

In addition, the composite magnetic material of the present invention comprises a coating layer (A) made of a material (a) and a material (b) in a powder in which particles of a metal magnetic material (b) are coated with a high resistance oxide magnetic material (a). ) Between the particles of the composite magnetic material in which the coating layer (C3) made of the oxide magnetic material (c3) is interposed. The oxide magnetic material (c3) is magnetite (Fe ₃ O _4). And at least one oxide magnetic material selected from the group consisting of γ-Fe ₂ O ₃ .

  Furthermore, the magnetic component of the present invention is characterized in that the composite magnetic material powder is compression-molded.

  According to the present invention, it is possible to produce a magnetic component that can be used in a high-frequency band of 10 MHz or more with high permeability without reducing the resistivity of a high-resistance oxide magnetic material film such as ferrite by heat treatment. This makes it possible to produce highly functional, small and thin magnetic components for switching power supplies such as notebook computers, small portable devices, and thin displays.

A. The present invention relates to a powder in which particles of a metal magnetic material (b) are coated with a high resistance oxide magnetic material (a), and between the coating layer (A) made of the material (a) and the particles of the material (b). A laminated composite magnetic material with a coating layer (C1) made of an oxide magnetic material (c1) interposed therebetween, characterized by satisfying any of the following requirements (1) and (2) A composite magnetic material is provided.
(1) A value equal to or lower than the equilibrium dissociation pressure at the heat treatment temperature of the oxide having a higher oxidation state than that of the oxide magnetic material (c1). Be.
(2) The oxide magnetic material (c1) is in the highest oxidation state that can be taken at the heat treatment temperature.

1. High resistance oxide magnetic material (a)
The high resistance oxide magnetic material (a) of the present invention refers to an oxide magnetic material having an electrical resistivity of 10 ⁴ Ω · cm or more. An insulating oxide magnetic material is preferable, and a high insulating ferrite among them is preferable, and Ni-Zn ferrite is more preferable.

2. Metallic magnetic material (b)
The metal magnetic material (b) of the present invention is preferably a magnetic material mainly composed of Fe, such as a Ni—Fe alloy or Sendust, or a magnetic material containing a Co magnetic element. The metal magnetic material (b) of the present invention is used as particles.

3. Oxide magnetic material (c1)
The oxide magnetic material (c1) of the present invention is an oxide magnetic material that satisfies any of the following requirements (1) and (2).
(1) A value equal to or lower than the equilibrium dissociation pressure at the heat treatment temperature of the oxide having a higher oxidation state than that of the oxide magnetic material (c1). Be.
(2) The oxide magnetic material (c1) is in the highest oxidation state that can be taken at the heat treatment temperature.

The material (c1) has the property of suppressing the reduction of the high-resistance oxide magnetic material (a) at the heat treatment temperature by satisfying any of the requirements (1) and (2). Further, unlike the high resistance oxide magnetic material (a), it is not always necessary to have a high resistance. However, the oxide magnetic material (c1) must be a magnetic material for improving the magnetic permeability, and is preferably at least one selected from the group consisting of magnetite Fe ₃ O ₄ and γ-Fe ₂ O _3. The above oxide magnetic materials can be used. Can be exemplified magnetite _Fe 3 _{O 4} as capable satisfies the requirements (1). Further, as capable satisfies the requirement (2), mention may be made of _γ-Fe 2 _{O 3.}

Here, the requirement (1) “equilibrium dissociation pressure of the high resistance oxide magnetic material (a) at the heat treatment temperature” means that the high resistance oxide magnetic material (a) is the high resistance oxide magnetic material (a ) This is the equilibrium constant (unit: atm) at the heat treatment temperature when dissociating into a lower oxidation state substance (oxide or metal) and one molecule of oxygen, and this is the partial pressure of oxygen in this dissociation equilibrium. Is equal to The heat treatment temperature refers to a temperature at which heat treatment is performed to improve the magnetic permeability of the composite magnetic material. Examples of the temperature include a temperature of 500 to 800 ° C., more preferably around 600 ° C. The “one substance in a low oxidation state” refers to a substance in an oxidation state that may first be taken when the high-resistance oxide magnetic material (a) is reduced. For example, when Ni—Zn ferrite is taken as an example of the high-resistance oxide magnetic material (a), Ni—Zn ferrite is a solid solution of NiO, ZnO, and Fe ₂ O ₃ , and one of these is in a low oxidation state. The materials are Ni, Zn, and Fe ₃ O ₄ , respectively.

  Similarly, “an equilibrium dissociation pressure at a heat treatment temperature of an oxide that is one higher in oxidation state than the oxide magnetic material (c1)” means an oxide that has one oxidation state higher than that in the oxide magnetic material (c1). Is the equilibrium constant (unit: atm) at the heat treatment temperature when dissociating from the oxide magnetic material (c1) and one oxygen molecule, and this is equal to the partial pressure of oxygen in the dissociation equilibrium.

The requirement (1) “an oxide having an oxidation state one higher than that of the oxide magnetic material (c1)” may be taken first when the oxide magnetic material (c1) is oxidized. An oxide in an oxidized state. For example, when Fe ₃ O ₄ is taken as an example of the oxide magnetic material (c1), Fe ₂ O ₃ is an oxide in a higher oxidation state.

  Table 1 shows the data of the equilibrium dissociation pressure of typical oxides. Such equilibrium dissociation pressure can be obtained from an oxidation-reduction equilibrium diagram (see Non-Patent Document 1).

In addition, the “highest oxidation state” of requirement (2) means that the metal oxide in the oxide magnetic material (c1) is in the highest oxidation state known to be able to be taken at the heat treatment temperature. Say. For example, for iron oxide, Fe ₂ O ₃ corresponds to this. This is because it is impossible to reduce the high-resistance oxide magnetic material (a) at the same time as it is further oxidized because it is in the highest oxidation state.

  In addition, whether the high resistance oxide magnetic material (a) and the oxide magnetic material (c1) satisfy any of the requirements (1) and (2) in the case where each includes a plurality of components, What is necessary is just to determine as follows (I) and (II). However, in the determination in (I) and (II), in both the high-resistance oxide magnetic material (a) and the oxide magnetic material (c1), cumulative addition is performed in the order of decreasing content to reach a total of 5% by weight. It may be determined that the minor component groups up to are not present.

  (I) Among the plurality of components of the oxide magnetic material (c1), the component satisfying the requirement (2) is excluded, and the remaining oxide component (hereinafter abbreviated as “c1 residual component”) is Proceed to II). However, if all oxide components in the material (c1) satisfy the requirement (2), it is judged that the material (c1) satisfies the requirement (2), and the following (II) is not required to be examined. It is.

  (II) Consider whether the requirement (1) is satisfied for the c1 residual component of (I) above. That is, among the oxide components of the high-resistance oxide magnetic material (a), the value of the equilibrium dissociation pressure for the component having the maximum equilibrium dissociation pressure is the oxidation state corresponding to each oxide component of the c1 residual component. If it is below the equilibrium dissociation pressure for the oxide having the lowest equilibrium dissociation pressure among the one higher oxide, the requirement (1) is satisfied, and if it is larger, the requirement (1) is not satisfied.

4). Coating layer (C1)
When the equilibrium dissociation pressure of such an oxide material is high, the oxide material is unstable. When a substance having a lower oxidation state corresponding to another oxide having a lower equilibrium dissociation pressure coexists, the oxide material The material is reduced and the substance (metal or oxide) is oxidized. That is, the ease of the redox reaction when the oxides contact each other or the metal and the oxide are determined by the equilibrium dissociation pressure of the oxide. For this reason, Fe reduces Fe ₂ O ₃ and NiO contained in the Ni—Zn ferrite, and itself is oxidized to FeO, and further FeO is oxidized to change to Fe ₃ O ₄ . Ni also reduces Fe ₂ O ₃ and oxidizes itself to NiO. For this reason, for example, when the metal magnetic material (b) is a particle of Ni—Fe alloy, and the Ni—Zn ferrite film is directly in contact as the high resistance oxide magnetic material (a), the metal magnetic material (b) Ni and Fe in the inside reduce Ni—Zn ferrite, and are likely to generate Fe ₃ O ₄ and FeO having low resistivity.

  Therefore, in order to suppress such a reduction reaction, in the present invention, an oxidation having the property of suppressing the reduction of the high-resistance oxide magnetic material (a) by satisfying any of the requirements (1) and (2). A coating layer (C1) made of the magnetic material (c1) is interposed between the coating layer (A) and the metal magnetic material (b) particles to form a laminated structure. For example, the metal magnetic material (b) particles are coated with the oxide magnetic material (c1), and then further coated with the high resistance oxide magnetic material (a). In addition, as a coating method, a coating means known in the technical field can be used, but preferably an ultrasonic excitation plating method (see Patent Document 3) can be used.

Two or more kinds of oxide magnetic materials (c1) can be used for the coating layer (C1) made of the material (c1) obtained by the coating. Further, the coating layer (C1) can be not only a single layer but also a plurality of laminated layers. For example, a coating layer (C1) containing Fe ₃ O ₄ which is an oxide magnetic material (c1) and a coating layer (C1 ′) containing γ-Fe ₂ O ₃ which is another oxide magnetic material (c1). A three-layer structure in which a coating of a coating layer (A) containing ferrite, which is a high-resistance oxide magnetic material (a), is formed on the laminated coating. Furthermore, components other than the material (c1) such as Fe ₃ O ₄ , for example, a high-resistance oxide magnetic material (a) such as high-insulating ferrite can be included as long as the effects of the present invention are not impaired. The amount is preferably less than 30% by weight based on the material (c1).

5. Coating layer (A)
Two or more types of high-resistance oxide magnetic materials (a) can be used for the coating layer (A) made of the material (a) obtained by the coating. Moreover, the coating layer (A) can be not only a single layer but also a plurality of laminated layers.

B. In the composite magnetic material described in A. above, the present invention further provides that the equilibrium dissociation pressure of the oxide magnetic material (c1) is the most oxidized state among the oxides corresponding to the metal in the metal magnetic material (b). A more preferable composite magnetic material satisfying the requirement (3) that the value is equal to or lower than the equilibrium dissociation pressure at the heat treatment temperature for the low-oxide is provided.

The material (c1) has the property of suppressing the reduction of the high-resistance oxide magnetic material (a) as described above, but in addition to satisfying the requirement (3), the metal magnetic material (b It also has the property of suppressing the reduction due to. As the oxide magnetic material (c1), it is preferable to use the material (c1) that satisfies the requirement (1). For example, a magnetite _Fe 3 _{O 4} as preferred.

  Here, the “equilibrium dissociation pressure of the oxide magnetic material (c1)” means that the oxide magnetic material (c1) has a lower oxidation state than the high-resistance oxide magnetic material (a) (oxide or Metal) and the equilibrium constant (unit atm) when dissociating into one oxygen molecule, which is equal to the partial pressure of oxygen in this dissociation equilibrium. In addition, “the oxide in the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b)” means an oxidation state that may be taken first when the metal is oxidized. Refers to oxide. For example, the oxide with the lowest oxidation state among the oxides corresponding to Ni is NiO, and the oxide with the lowest oxidation state among the oxides corresponding to Fe is FeO. Further, the “equilibrium dissociation pressure at the heat treatment temperature for the oxide” means the equilibrium at the heat treatment temperature when the oxide dissociates into a single oxidation molecule, ie, a metal having a lower oxidation state. This is a constant (unit: atm), which is equal to the partial pressure of oxygen in such dissociation equilibrium. The heat treatment temperature refers to a temperature at which heat treatment is performed to improve the magnetic permeability of the composite magnetic material. As the temperature, a temperature of 500 to 800 ° C., more preferably around 600 ° C. is preferably used.

  When the oxide magnetic material (c1) and the metal magnetic material (b) each include a plurality of components, the equilibrium dissociation pressure of the oxide magnetic material (c1), which is a requirement of (3), is reduced to the metal magnetic material ( b) In determining whether or not the value is equal to or lower than the equilibrium dissociation pressure for the oxide in the lowest oxidation state among the oxides corresponding to the metal in the oxide, each oxide component of the oxide magnetic material (c1) Among the oxides having the lowest equilibrium state, the value of the equilibrium dissociation pressure for the oxide component having the maximum equilibrium dissociation pressure is the lowest among the oxides corresponding to the metal components in the metal magnetic material (b). If the value is equal to or less than the value of the equilibrium dissociation pressure of the oxide having the minimum equilibrium dissociation pressure, the requirement (3) is satisfied, and if the value is larger, the requirement (3) is not satisfied. However, in determining the requirement (3), in both the oxide magnetic material (c1) and the metal magnetic material (b), the minor components until the total amount reaches 5% by weight in the order of increasing content. May be determined as not present.

For example, Ni—Fe ferrite (solid solution of NiO, ZnO, Fe ₂ O ₃ ) is used as the high resistance oxide magnetic material (a), Ni—Fe alloy is used as the metal magnetic material (b), and the oxide magnetic material ( A combination of Fe ₃ O ₄ can be employed as c1). That is, Fe ₃ O ₄ that is the oxide magnetic material (c1) does not reduce the Ni—Fe ferrite that is the high resistance oxide magnetic material (a), and is not reduced by the Ni—Fe ferrite. In addition, Fe ₃ O ₄ which is the oxide magnetic material (c1) is reduced by Fe in the metal magnetic material (b), but is brought into an equilibrium state by heat treatment at 600 ° C., and even at a temperature higher than 600 ° C. The dissociation pressure is relatively close, and the reduction of Fe ₃ O ₄ is suppressed. Moreover, it is not reduced by Ni.

C. The present invention provides a more preferable composite magnetic material characterized in that, in the composite magnetic material described in A. above, all of the following requirements (4) to (7) are satisfied.
(4) The equilibrium at the heat treatment temperature of the oxide having the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b) having an equilibrium dissociation pressure at the heat treatment temperature of the oxide magnetic material (c1). The value is larger than the dissociation pressure.
(5) The oxide magnetic material (c1) is reduced by the metal magnetic material (b) at the heat treatment temperature to produce the oxide magnetic material (c2).
(6) The high-resistance oxide magnetic material (a) has an equilibrium dissociation pressure at a heat treatment temperature equal to or lower than the equilibrium dissociation pressure at the heat treatment temperature of an oxide having a higher oxidation state than the generated oxide magnetic material (c2). Value.
(7) The heat treatment temperature of the oxide having the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b) having an equilibrium dissociation pressure at the heat treatment temperature of the produced oxide magnetic material (c2) The value should be equal to or less than the equilibrium dissociation pressure.

  The material (c1) is composed of the above-mentioned A. As described above, in the heat treatment temperature, it has the property of suppressing the reduction of the high-resistance oxide magnetic material (a). In addition to this, the material (c1) is supposed to be a metal magnetic material ( Even if reduced by b), the generated material (c2) is also an oxide magnetic material, and this material (c2) also suppresses the reduction of the high-resistance oxide magnetic material (a) and is already reduced. Therefore, the metal magnetic material (b) has a property of suppressing reduction.

The oxide magnetic material (c1) is preferably A. The material (c1) that satisfies the requirement (2) described in 1) is used. For example, γ-Fe ₂ O ₃ can be mentioned as a suitable one.

  Here, the requirement (4) satisfies the above-mentioned B.1. Means that the oxide magnetic material (c1) is reduced by the metal magnetic material (b). The requirement (5) means that the material produced by reducing the oxide magnetic material (c1) is also an oxide magnetic material. The requirements (6) and (7) are obtained by replacing the oxide magnetic material (c1) with the oxide magnetic material (c2) in the requirement (1) of the above A. and the requirement (3) of the above requirement B. This means that the produced oxide magnetic material (c2) suppresses reduction of the high-resistance oxide magnetic material (a) and also suppresses reduction by the metal magnetic material (b).

For example, Ni—Fe ferrite was used as the high resistance oxide magnetic material (a), Ni—Fe alloy was used as the metal magnetic material (b), and γ-Fe ₂ O ₃ was used as the oxide magnetic material (c1). In this case, γ-Fe ₂ O _{3 that} is the oxide magnetic material (c1) does not reduce the Ni—Fe ferrite that is the high resistance oxide magnetic material (a), and is not reduced by the Ni—Fe ferrite. Moreover, although γ-Fe ₂ O ₃ which is the oxide magnetic material (c1) is reduced by Fe and Ni in the metal magnetic material (b), the generated oxide magnetic material (c2) is oxidized as described above. Since it becomes Fe ₃ O ₄ which is a magnetic material (c1), the above A. As in the invention described in (1), the property of suppressing the reduction of the high-resistance oxide magnetic material (a) is still maintained, and thereafter the reduction by the metal magnetic material (b) is suppressed at the heat treatment temperature (˜600 ° C.). It also has the property to do.

D. The present invention relates to a powder in which particles of a metal magnetic material (b) are coated with a high resistance oxide magnetic material (a), and between the coating layer (A) made of the material (a) and the particles of the material (b). An equilibrium dissociation of a high-resistance oxide magnetic material (a) at a temperature 200 ° C. higher than the heat treatment temperature, which is a laminated composite magnetic material with a coating layer (C1) made of the oxide magnetic material (c1) interposed Satisfying the requirement (8) that the pressure is not more than 100 times the equilibrium dissociation pressure at a temperature 200 ° C. higher than the heat treatment temperature of the oxide having one higher oxidation state than the oxide magnetic material (c1). A composite magnetic material is provided.

  The present invention provides the above-described A. In the composite magnetic material described in 1), the reference temperature of the equilibrium dissociation pressure is replaced by “a temperature higher by 200 ° C. than the heat treatment temperature” instead of the “heat treatment temperature”, and the oxide is used as a reference for the magnitude relationship of the equilibrium dissociation pressure. The equilibrium dissociation pressure of the oxide having one higher oxidation state than that of the magnetic material (c1) is not 100% but 100 times. A. above. The composite magnetic material described in is redefined in another expression.

Preferably the A. above. The requirement (1) is preferably satisfied, and the combination of Ni—Fe ferrite as the high resistance oxide magnetic material (a) and Fe ₃ O ₄ as the oxide magnetic material (c1) satisfies both requirements.

E. According to the present invention, in the composite magnetic material described in the above D., the equilibrium dissociation pressure of the oxide magnetic material (c1) at a temperature 200 ° C. higher than the heat treatment temperature corresponds to the metal in the metal magnetic material (b). More preferable composite characterized by satisfying the requirement (9) that the value is 100 times or less the equilibrium dissociation pressure at a temperature 200 ° C. higher than the heat treatment temperature for the oxide in the lowest oxidation state among the oxides to be oxidized Provide a magnetic material.

  The present invention provides the above-described B. In the composite magnetic material described in 1), the temperature used as the reference for the equilibrium dissociation pressure is replaced with “temperature higher by 200 ° C. than the heat treatment temperature” instead of “heat treatment temperature”, and metal magnetism is used as a reference for the magnitude relationship of the equilibrium dissociation pressure Among the oxides corresponding to the metal in the material (b), the equilibrium dissociation pressure for the oxide in the lowest oxidation state is 100 times instead of 1 time. B. above. The composite magnetic material described in is redefined in another expression.

For example, when Fe ₃ O ₄ is employed as the oxide magnetic material (c1) and Fe is employed as the metal magnetic material (b), when the heat treatment temperature is 600 ° C., the equilibrium dissociation pressure of 600 ° C. is Among oxides corresponding to the oxide magnetic material (c1) and the metal magnetic material (b), the oxide (FeO) having the lowest oxidation state is the same at 1.3 × 10 ⁻²⁵ atm and satisfies the requirement (3). However, at 800 ° C., which is 200 ° C. higher than the heat treatment temperature, the oxide magnetic material (c1) is 6.3 × 10 ⁻¹⁸ atm, and the oxide having the lowest oxidation state among the oxides corresponding to the metal magnetic material (b). The product (FeO) is 9.5 × 10 ⁻²⁰ atm and satisfies the requirement (9).

Preferably the above B.I. It is preferable to satisfy the requirement (3), and the combination of Fe ₃ O ₄ as the oxide magnetic material (c1) and Fe or Ni as the metal magnetic material (b) satisfies both requirements.

F. The present invention provides a more preferable composite magnetic material characterized in that, in the composite magnetic material described in the above D., all of the following requirements (10) to (13) are satisfied.
(10) The equilibrium at the heat treatment temperature of the oxide having the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b) having an equilibrium dissociation pressure at the heat treatment temperature of the oxide magnetic material (c1). The value is larger than the dissociation pressure.
(11) The oxide magnetic material (c1) is reduced by the metal magnetic material (b) at the heat treatment temperature to produce the oxide magnetic material (c2).
(12) The high-resistance oxide magnetic material (a) has an equilibrium dissociation pressure at a temperature 200 ° C. higher than the heat treatment temperature, higher than the heat treatment temperature of the oxide whose oxidation state is one higher than that of the generated oxide magnetic material (c2). The value should be 100 times or less of the equilibrium dissociation pressure at a temperature 200 ° C higher.

  (13) The oxide having the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b) having an equilibrium dissociation pressure at 200 ° C. higher than the heat treatment temperature of the generated oxide magnetic material (c2) The value is equal to or less than 100 times the equilibrium dissociation pressure at a temperature 200 ° C. higher than the heat treatment temperature.

  The present invention provides the C.I. In the composite magnetic material described in (1), the temperature serving as the reference for the equilibrium dissociation pressure is replaced with “temperature higher by 200 ° C. than the heat treatment temperature” instead of the “heat treatment temperature” (however, the requirements (10) and (11) are excluded). ) And the equilibrium dissociation pressure as a criterion, the “equilibrium dissociation pressure for the oxide in the lowest oxidation state among oxides corresponding to the metal in the metal magnetic material (b)” and “the oxide magnetic material ( c2) “Equilibrium dissociation pressure of oxide having one higher oxidation state” is not 100% but 100 times. C. above. The composite magnetic material described in is redefined in another expression.

Preferably said C.I. It is also preferable to satisfy the requirements (6) and (7), Ni-Fe ferrite as the high resistance oxide magnetic material (a), γ-Fe ₂ O ₃ as the oxide magnetic material (c1), and metal magnetic material (b The combination of Fe and Ni also satisfies these requirements.

G. In the powder in which the particles of the metal magnetic material (b) are coated with the high-resistance oxide magnetic material (a), the present invention is also provided between the coating layer (A) made of the material (a) and the material (b) particles. And a laminated composite magnetic material with a covering layer (C3) made of an oxide magnetic material (c3) interposed therebetween, wherein the oxide magnetic material (c3) is magnetite (Fe ₃ O ₄ ) and γ-Fe _2. A composite magnetic material comprising at least one oxide magnetic material selected from the group consisting of O ₃ is provided.
1. High resistance oxide magnetic material (a), metal magnetic material (b), coating layer (A)
A. above. 1. 2. 5. It is the same.
2. Oxide magnetic material (c3)
The oxide magnetic material (c3) is at least one oxide magnetic material selected from the group consisting of magnetite (Fe ₃ O ₄ ) and γ-Fe ₂ O ₃ . The oxide magnetic material (c3) is a magnetic material for improving the magnetic permeability.

Fe ₃ O ₄ that is the oxide magnetic material (c3) does not reduce, for example, Ni—Fe ferrite that is the high-resistance oxide magnetic material (a), and is not reduced to Ni—Fe ferrite. Further, although it is reduced to Fe in the metal magnetic material (b), it is in an equilibrium state by heat treatment at 600 ° C. or lower, and the equilibrium dissociation pressure is relatively close even at 600 ° C. or higher, and the reduction of Fe ₃ O ₄ is suppressed. The Further, it is not reduced to Ni (or Co) in the metal magnetic material (b).

Γ-Fe ₂ O _{3 that} is an oxide magnetic material (c3) does not reduce, for example, Ni—Fe ferrite that is a high-resistance oxide magnetic material (a), and is not reduced to Ni—Fe ferrite. Further, Fe with metal magnetic particles, but is reduced to Ni (other Co), there is no particular problem since the _Fe 3 _{O 4.}

Further, as the oxide magnetic material (c3), a mixture of Fe ₃ O ₄ and γ-Fe ₂ O ₃ can be used, and the same effect as when each of them is used alone can be obtained.

3. Coating layer (C3)
In the present invention, the coating layer (C3) made of the oxide magnetic material (c3) is interposed between the coating layer (A) and the metal magnetic material (b) particles. For example, the metal magnetic material (b) particles are coated with the oxide magnetic material (c3) and then further coated with the insulating oxide magnetic material (a). As a coating method, a coating means known in the technical field can be used, and an ultrasonic excitation plating method (see Patent Document 3) is preferable.

Two or more kinds of oxide magnetic materials (c3) can be used for the coating layer (C3) made of the material (c3) obtained by the coating. Further, the coating layer (C3) can be not only a single layer but also a plurality of laminated layers. For example, a coating layer (A) containing ferrite, which is an insulating oxide magnetic material (a), is formed on a coating film obtained by laminating a coating layer containing Fe ₃ O ₄ and a coating layer containing γ-Fe ₂ O _3. A three-layer structure may be used. Furthermore, components other than the material (c3), for example, an insulating oxide magnetic material (a) such as highly insulating ferrite, can be included within the range not impairing the effects of the present invention. It is less than 30% by weight based on c3).

H. The present invention also provides A. ~ G. A magnetic component is provided in which the powder of the laminated composite magnetic material described in (1) is compression molded.
As compression molding, a method known in the technical field can be used.

  Embodiments of the present invention will be described below with reference to the drawings.

  The production of the ferrite-coated metal particle powder was performed by the ultrasonic excitation ferrite plating method as follows.

As particles of the metal magnetic material, 10 g of Ni78Mo5Fe particles (Ni 78 wt%, Mo 5 wt%, Fe 17 wt%; average particle diameter 8 μm) prepared by a water atomization method were used. As a pretreatment for ferrite plating, these particles were placed in a mixed solution of H ₂ O, H ₂ SO ₄ and HCl (liquid temperature 70 ° C.), and ultrasonic waves were applied for 5 minutes.

Thereafter, Ni78Mo5Fe particles were transferred into a glass reaction vessel containing pure water, and 19.5 kHz ultrasonic waves were applied. While supplying the reaction solution (H ₂ O + FeCl ₂ .4H ₂ O) and the oxidation solution (H ₂ O + NaNO ₂ ) to this reaction vessel, ammonia water was appropriately added dropwise. This plating process was performed for 15 minutes. After the plating treatment, the particles were classified and dried. As a result of the above treatment, an Fe ₃ O ₄ film having a thickness of about 30 nm was formed on the surface of the metal magnetic particles.

Subsequently, a Ni—Zn-based ferrite film was formed as follows.
Ni78Mo5Fe particles coated with Fe ₃ O ₄ were transferred into a glass reaction vessel containing pure water, and 19.5 kHz ultrasonic waves were applied. While supplying the reaction solution (H ₂ O + FeCl ₂ .4H ₂ O + NiCl ₂ .6H ₂ O + ZnCl ₂ ) and the oxidation solution (H ₂ O + NaNO ₂ ) to this reaction vessel, aqueous ammonia was appropriately added dropwise. This plating process was performed for 30 minutes. After the plating treatment, the particles were classified and dried. By the above treatment, a Ni—Zn ferrite film having a thickness of about 100 nm was formed on the surface of the metal magnetic particles.

The powder of the laminated coated Ni78Mo5Fe particles (FIG. 1) thus obtained was filled into a cemented carbide mold, and the inner diameter was 3 mmφ, the outer diameter was 8 mmφ, and the high diameter was uniaxially pressed at 980 MPa (10 ton weight / cm ² ). It was molded into a ring core shape of about 8 mm. Thereafter, the molded body was fired at 600 ° C. in the air.

  The primary and secondary windings were wound around this ring core for 5 turns, respectively, and the complex permeability μ = μ ′ + iμ ”was measured with a BH analyzer in a frequency range of 10 kHz to 10 MHz. Data R in FIG. The frequency dependence of the real part μ ′ of the complex permeability is shown, and the data I shows the frequency dependence of the imaginary part μ ″ of the complex permeability. Further, data R "and data I" in the figure show the frequency dependence of the real part .mu. 'And imaginary part .mu.' 'Of the complex permeability before heat treatment, respectively.

(Comparative example)
As comparison data, Ni78Mo5Fe particles containing only a ferrite film were ferrite-plated under the same conditions as described in the example (FIG. 2), and the complex permeability of the heat-treated product after compression molding as in the example was measured. . The frequency dependence of the real part μ ′ and imaginary part μ ″ is shown in the data R ′ and I ′ of FIG. 3, respectively.

The magnetic permeability was greatly improved by heat treatment in both Examples and Comparative Examples. However, it can be seen that the comparative example has a higher permeability on the low frequency side than the examples, but the frequency characteristics are poor, and the insulating properties of the coating are deteriorated. On the other hand, in the examples, good frequency characteristics up to 10 MHz are shown, and it can be seen that the insulation of the film is maintained.
In this embodiment, Fe ₃ O ₄ is used as the intermediate layer, but γ-Fe ₂ O ₃ may be used.

It is the figure which showed the double layer coating Ni78Mo5Fe particle | grains which is an Example of this invention. It is the figure which showed the Ni78Mo5Fe particle | grains of the ferrite coating only which is a comparative example of this invention. It is the figure which showed the frequency characteristic of the magnetic permeability of the Example and comparative example of this invention.

Explanation of symbols

1 Metal magnetic particles 2 Ferrite coating 3 Fe ₃ O ₄ coating

Claims (9)

In the powder in which the particles of the metal magnetic material (b) are coated with the high resistance oxide magnetic material (a), the oxide magnetism is interposed between the coating layer (A) made of the material (a) and the particles of the material (b). A composite magnetic material laminated with a covering layer (C1) made of the material (c1), wherein the composite magnetic material satisfies one of the following requirements (1) and (2):
(1) A value equal to or lower than the equilibrium dissociation pressure at the heat treatment temperature of the oxide having a higher oxidation state than that of the oxide magnetic material (c1). Be.
(2) The oxide magnetic material (c1) is in the highest oxidation state that can be taken at the heat treatment temperature.   Further, the equilibrium dissociation at the heat treatment temperature of the oxide having the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b) has an equilibrium dissociation pressure at the heat treatment temperature of the oxide magnetic material (c1). The composite magnetic material according to claim 1, wherein the requirement (3) is a value equal to or lower than the pressure. The composite magnetic material according to claim 1, further satisfying any of the following requirements (4) to (7).
(4) The equilibrium at the heat treatment temperature of the oxide having the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b) having an equilibrium dissociation pressure at the heat treatment temperature of the oxide magnetic material (c1). The value is larger than the dissociation pressure.
(5) The oxide magnetic material (c1) is reduced by the metal magnetic material (b) at the heat treatment temperature to produce the oxide magnetic material (c2).
(6) The high-resistance oxide magnetic material (a) has an equilibrium dissociation pressure at a heat treatment temperature equal to or lower than the equilibrium dissociation pressure at the heat treatment temperature of an oxide having a higher oxidation state than the generated oxide magnetic material (c2). Value.
(7) The heat treatment temperature of the oxide having the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b) having an equilibrium dissociation pressure at the heat treatment temperature of the produced oxide magnetic material (c2) The value should be equal to or less than the equilibrium dissociation pressure.   In the powder in which the particles of the metal magnetic material (b) are coated with the high resistance oxide magnetic material (a), the oxide magnetism is interposed between the coating layer (A) made of the material (a) and the particles of the material (b). A composite magnetic material laminated with a coating layer (C1) made of the material (c1), and the equilibrium dissociation pressure of the high resistance oxide magnetic material (a) at a temperature 200 ° C. higher than the heat treatment temperature is It satisfies the requirement (8) that the oxide has one higher oxidation state than the magnetic oxide material (c1) and has a value equal to or less than 100 times the equilibrium dissociation pressure at a temperature 200 ° C. higher than the heat treatment temperature. Composite magnetic material.   Furthermore, the oxide dissociation pressure at a temperature 200 ° C. higher than the heat treatment temperature of the oxide magnetic material (c1) is the oxide with the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b). 5. The composite magnetic material according to claim 1, wherein the requirement (9) is 100 or less of the equilibrium dissociation pressure at a temperature 200 ° C. higher than the heat treatment temperature. Furthermore, all the following requirements (10)-(13) are satisfy | filled, The composite magnetic material of Claim 4 characterized by the above-mentioned.
(10) The equilibrium at the heat treatment temperature of the oxide having the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b) having an equilibrium dissociation pressure at the heat treatment temperature of the oxide magnetic material (c1). The value is larger than the dissociation pressure.
(11) The oxide magnetic material (c1) is reduced by the metal magnetic material (b) at the heat treatment temperature to give the oxide magnetic material (c2).
(12) The high-resistance oxide magnetic material (a) has an equilibrium dissociation pressure at a temperature 200 ° C. higher than the heat treatment temperature, higher than the heat treatment temperature of the oxide whose oxidation state is one higher than that of the generated oxide magnetic material (c2). The value should be 100 times or less of the equilibrium dissociation pressure at a temperature 200 ° C higher.
(13) The oxide having the lowest oxidation state among the oxides corresponding to the metal in the metal magnetic material (b) having an equilibrium dissociation pressure at 200 ° C. higher than the heat treatment temperature of the generated oxide magnetic material (c2) The value is equal to or less than 100 times the equilibrium dissociation pressure at a temperature 200 ° C. higher than the heat treatment temperature. In the powder in which the particles of the metal magnetic material (b) are coated with the high resistance oxide magnetic material (a), the oxide magnetism is interposed between the coating layer (A) made of the material (a) and the particles of the material (b). A laminated composite magnetic material with a coating layer (C3) made of material (c3) interposed therebetween, wherein the oxide magnetic material (c3) is composed of magnetite (Fe ₃ O ₄ ) and γ-Fe ₂ O ₃ A composite magnetic material comprising at least one oxide magnetic material selected from the group.   The laminated composite magnetic material according to any one of claims 1 to 7, wherein the high-resistance oxide magnetic material (a) is a highly insulating ferrite. 9. A magnetic component, wherein the laminated composite magnetic material powder according to claim 1 is compression-molded.

Images