WO2005024859A1 - Soft magnetic material and method for producing same - Google Patents

Abstract

Disclosed are a soft magnetic material having an optimum electrical resistivity and a method for producing such a soft magnetic material. The soft magnetic material comprises a plurality of composite magnetic particles (30). Each of the composite magnetic particles (30) comprises a metal magnetic particle (10) and an insulating coating film (20) which covers the surface of the metal magnetic particle (10) and contains at least one substance selected from the group consisting of zirconium oxide, aluminum oxide and silicon oxide. The soft magnetic material has an electrical resistivity of not less than 3,000 μΩcm and not more than 50,000 μΩcm, and a magnetic permeability μ of not less than 2,000 and not more than 4,000. A method for producing such a soft magnetic material comprises a step for forming a shaped body by compressing a plurality of the composite magnetic particles (30) and a step for subjecting the shaped body to a first heat treatment at not less than 400˚C and not more than 900˚C.

Description

 Specification

 Soft magnetic material and method of manufacturing the same

 Technical field

 The present invention relates to a soft magnetic material and a method of manufacturing the same, and more particularly, to a soft magnetic material including composite magnetic particles having metal magnetic particles and an insulating film, and a method of manufacturing the same.

 ^ Technology

 In recent years, densification and miniaturization of electric and electronic parts have been achieved, and it is required to perform more precise control with power saving in motor core, core score, and the like. For this reason, development of soft magnetic materials used for these electric and electronic components and having excellent magnetic properties in the middle high frequency region has been advanced. In order for soft magnetic materials to have excellent magnetic properties in the middle to high frequency region, it is necessary to have high saturation magnetic flux density, high permeability, high resitivity, and electrical resistivity.

 Such a soft magnetic material is disclosed, for example, in Japanese Patent Laid-Open No. 6-267723 (Patent Document 1).

 Patent Document 1: Japanese Patent Application Laid-Open No. 6-267723

 Disclosure of the invention

 Problem that invention tries to solve

 However, the soft magnetic materials disclosed in the above-mentioned documents have the problem that the electrical resistivity is too high and the magnetic flux density is small.

 Therefore, the present invention has been made to solve the problems as described above, and it is an object of the present invention to provide a soft magnetic material having an optimized electrical resistivity, and a method of manufacturing the same. It is.

 Means to solve the problem

The soft magnetic material according to the present invention comprises a plurality of composite magnetic particles. Each of the plurality of composite magnetic particles includes metal magnetic particles and at least one selected from the group consisting of aluminum oxide, zirconium oxide, and zirconium oxide surrounding the surface of the metal magnetic particles. And an insulating film. The electrical resistivity p of the soft magnetic material is 3000 μΩ cm or more and 50000 / i Ω cm or less.

 More preferably, the magnetic permeability μ of the soft magnetic material is 2000 or more and 4000 or less. The method for producing a soft magnetic material according to the present invention is a method for producing the above-mentioned soft magnetic material, which comprises metal magnetic particles, and the surfaces of the metal magnetic particles, aluminum oxide, zinc oxide and zinc oxide oxide. Forming a molded body by pressing a plurality of composite magnetic particles having an insulating film containing at least one selected from the group consisting of A heat treatment step of 1 is provided.

Preferably, in the method of manufacturing a soft magnetic material, after pressing the formed body after the first heat treatment, the formed body is subjected to a second heat treatment at a temperature of 400 ° C. to 900 ° C. under atmospheric pressure. It has a process. Effect of the invention

 According to the present invention, it is possible to provide a soft magnetic material having desired magnetic properties and a method for producing the same.

 Brief description of the drawings

FIG. 1 is a schematic view showing a cross section of a soft magnetic material according to an embodiment of the present invention.

 Explanation of sign

 [0011] 10 metal magnetic particles, 20 insulating coatings, 30 composite magnetic particles.

 BEST MODE FOR CARRYING OUT THE INVENTION

 The soft magnetic material according to the present invention has a plurality of composite magnetic particles, and each of the composite magnetic particles has metal magnetic particles and an insulating film surrounding the surface of the metal magnetic particles.

The metallic magnetic particles are generally composed of iron (Fe). While the metal magnetic particles are not limited to iron, they may be composed of other magnetic particles. For example, metal magnetic particles can be iron (Fe) -silicon (Si) based alloys, iron (Fe) -nitrogen (N) based alloys, iron (Fe) -biquettes (Ni) based alloys, iron (Fe) —Carbon (C) -based alloy, iron (Fe) -boron (B) -based alloy, iron (Fe) _ cobalt (Co) -based alloy, iron (Fe) _ phosphorus (P) -based alloy, iron (Fe) _ It may be formed of a nickel (Ni) -cobalt (Co) based alloy, an iron (Fe) -aluminum (A1) -silicon (Si) based alloy or the like. The metal magnetic particles may be either a single metal or an alloy. The average particle diameter of the metal magnetic particles is preferably 5 μm or more and 200 μm or less. When the average particle size of the metal magnetic particles is less than 5 / m, the metal is easily oxidized, which may deteriorate the magnetic properties of the soft magnetic material. In addition, when the average particle size of the metal magnetic particles exceeds 200 μm, the compressibility of the mixed powder is reduced in the subsequent forming process. As a result, the density of the molded product obtained by the molding process may be reduced, making it difficult to handle.

 [0015] The average particle diameter means the particle diameter of particles in which the sum of mass from the smaller one reaches 50% of the total mass in the histogram of particle diameters measured by the sieve method, that is, 50% particles. The diameter is D.

 The insulating coating can be composed of an oxide insulator containing aluminum and Z or zirconium and / or cyne. By covering the surface of the metal magnetic particles with an insulating coating, the electrical resistivity p of the soft magnetic material can be increased. As a result, it is possible to suppress the flow of the eddy current between the metal magnetic particles, and to reduce the iron loss of the soft magnetic material caused by the eddy current.

 According to the present invention, the electrical resistivity p of the soft magnetic material is 3000 μΩcm or more and 50000 μΩcm or less. If the electrical resistivity p is less than 3000 μΩ cm, the electrical resistivity decreases and the effect of suppressing the eddy current decreases.

On the other hand, when the electrical resistivity p exceeds 50000 μΩ cm, the electrical resistivity becomes too large, which is not preferable. Specifically, the increase in the electrical resistivity p means that the amount of the insulating coating is increased. If the amount of the insulating coating is too large, magnetic properties such as permeability and magnetic flux density will deteriorate.

In order to enhance the above effect, the electrical resistivity p of the soft magnetic material is at least 6000 μ Ω cm 15

It is desirable that the force S be less than or equal to 000 μ Q cm, and further more than or equal to 8000 μ Ω cm and less than or equal to 10000 μ Ω cm.

[0020] The thickness of the insulating coating is preferably 以上 005 μm to μ20 μm. By setting the thickness of the insulating coating to not less than 0.005 g, force S can effectively suppress energy loss due to eddy current. Also, by setting the thickness of the insulating film to 20 zm or less, the volume ratio of the insulating film in the soft magnetic material does not become too large. In this way, A soft magnetic material having a saturation flux density can be formed.

 More preferably, the magnetic permeability μ of the soft magnetic material is 2000 or more and 4000 or less. More preferably, the permeability / i of the soft magnetic material is 2500 or more and 3500 or less.

 Next, a method of manufacturing the above-mentioned soft magnetic material will be described. First, prepare multiple composite magnetic particles. The composite magnetic particles are placed in a mold and, for example, the mixed powder is pressure-formed under conditions of a pressure of 390 MPa or more and 150 OMPa or less. Thereby, the mixed powder can be compressed to obtain a compact. The pressure forming atmosphere is preferably an inert gas or a reduced pressure atmosphere. In this case, oxidation of the mixed powder by oxygen in the atmosphere can be prevented. By using the warm forming method and the mold lubrication method which are known techniques in the forming process of the formed body, the formed body is densified, the space factor is improved, and the magnetic property is improved. The powder temperature during warm molding is preferably 100 ° C to 180 ° C.

 In order to strengthen the bonds between the composite magnetic particles, an organic substance may be interposed between the composite magnetic particles. In this case, the composite magnetic particles and the organic matter need to be mixed in advance. The mixing method is not particularly limited, for example, mechanical bonding, vibration ball milling, planetary ball milling, mechanofusion, coprecipitation, chemical vapor deposition (CVD), physical vapor deposition (PVD), plating, It is possible to use any of sputtering method, vapor deposition method, sol-gel method and the like.

 As the organic substance, thermoplastic resins such as thermoplastic polyimide, thermoplastic polyamide, thermoplastic polyamide imide, polyphenylene sulfide, polyamide imide, polyether sulfone, polyether imide or polyether ether ketone can be used. . By providing such an organic substance, the organic substance functions as a lubricant among the plurality of composite magnetic particles. This can suppress breakage of the insulating coating during the molding process.

Next, the compact obtained by pressure formation is heat-treated at a temperature of 400 ° C. or more and 900 ° C. or less. A large number of strains and dislocations are generated inside the compact obtained through the pressure forming process, and the strains and dislocations cause a decrease in permeability and an increase in coercivity. Heat treatment is performed on the compact for the purpose of removing the strain and dislocation. Such heat treatment is required even when organic matter is interposed between composite magnetic particles. In order to improve the density of the soft magnetic material and remove dislocations and strains in the soft magnetic material, the soft magnetic material is compressed again to improve its density, and then the soft magnetic material is subjected to atmospheric pressure. Heat treatment at a temperature of 400 ° C to 900 ° C.

 In this way, the soft magnetic material according to the present invention can be manufactured.

 Generally, when the coercive force of the soft magnetic material is small, the hysteresis loss is small, and when the hysteresis loss is large, the coercive force is also large, and when the coercive force is small, the permeability is large. The improvement of the permeability leads to the reduction of the hysteresis loss. In the present invention, the material is configured to have a high permeability, which leads to a reduction in hysteresis loss.

 In addition, in order to reduce eddy current loss, it is important to maintain insulation between composite magnetic particles. By increasing the resistivity of the soft magnetic material as a balta body, it leads to the reduction of the eddy current loss. In particular, eddy current loss includes eddy current loss in each particle and eddy current loss generated between particles. It is necessary to reduce the eddy current loss across the particles, and in the present invention, it is possible to reduce the eddy current loss because the specific resistance of the soft magnetic material is increased in the range without damaging the magnetic properties.

 The composition of the aluminum oxide, the zirconium oxide and the silicon oxide which constitute the insulating film in the present invention is not particularly limited. Specifically, the composition of aluminum oxide is not limited to Al 2 O 3, and the atomic ratio of aluminum to oxygen may be changed as appropriate. In addition, the composition ratio of zirconium oxide may be changed as appropriate to the ratio of zirconium and oxygen. In addition, the composition ratio of carbon dioxide may also be appropriately changed in the ratio of carbon and oxygen.

 FIG. 1 is a schematic view showing a cross section of the soft magnetic material according to the embodiment of the present invention.

 Referring to FIG. 1, the soft magnetic material comprises a plurality of composite magnetic particles 30. Each of the plurality of composite magnetic particles 30 encloses the metal magnetic particle 10 and the surface of the metal magnetic particle 10, and includes at least one selected from the group consisting of an amine oxide, zirconium oxide and an acid oxide. And an insulating film 20. The electrical resistivity p of the soft magnetic material is 3000 μΩ cm or more and 50000 μΩ cm or less. An organic substance 40 intervenes between the composite magnetic particles 30. (Example 1)

[0032] In Example 1, the soft magnetic material according to the present invention was manufactured. First, as metal magnetic particles Then, using an iron powder having an average particle size of 70 μm 湿式, this iron powder was coated with an Al film as an insulation film using a wet method. At this time, the thickness of the insulating film was made to be lOOnm.

. This coating formed composite magnetic particles in which the surface of the iron powder was surrounded by an Al 2 O film.

[0033] A mixed powder was formed by mixing the composite magnetic particles and particles of a polyphenol sulfide resin having an average particle diameter of 100 μm or less. The mixed powder was placed in a mold and subjected to pressure forming. At this time, pressure molding was performed in a nitrogen gas atmosphere, the temperature of the mold was normal temperature, and the pressure was 882 MPa. Thus, a sample of a molded body was obtained. Next, the compact was heat treated. The heat treatment was performed for 3 hours at a temperature of 800 ° C. in a nitrogen gas atmosphere. Thereafter, the electrical resistivity, density, and permeability of the sample were measured. The electrical resistivity was 5670 μ cm, the density was 7.5 g / cm ³ , and the permeability μ was 2050.

 (Comparative example 1)

 In Comparative Example 1, Somalloy 500 (trade name) was prepared as composite magnetic particles. Somalloy 500 is a composite magnetic particle in which a phosphate film is formed on the surface of iron powder. A mixed powder was formed by mixing particles of polyphenylene sulfide with the composite magnetic particles. The mixed powder was placed in a mold and pressed. At this time, pressure molding was performed in a nitrogen gas atmosphere, the temperature of the mold was normal temperature, and the pressure was 882 MPa. Thereby, a molded body was obtained.

 Next, the compact was heat-treated. The heat treatment was performed for 0.5 hours at a temperature of 300 ° C. in a nitrogen gas atmosphere. Thereafter, the electrical resistivity and permeability of the molded body were measured. The electrical resistivity was 350 / Ω cm, and the permeability μ was 600.

 From the above results, it was confirmed that the soft magnetic material according to the present invention can satisfy the magnetic characteristics required for the soft magnetic material.

 It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above description but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

The scope of the claims [1] comprising a plurality of composite magnetic particles (30),  Each of the plurality of composite magnetic particles (30) surrounds the surface of the metal magnetic particles (10) and the metal magnetic particles (10), and is selected from the group consisting of aluminum oxide, zinc oxide, and silica oxide. And an insulating film (20) containing at least one of  Soft magnetic material with an electrical resistivity p force of 000 μΩ cm or more and 50000 μ Ω cm or less. [2] The soft magnetic material according to claim 1, wherein the magnetic permeability μ is 2000 or more and 4000 or less. [3] A method of manufacturing a soft magnetic material according to claim 1 or 2, wherein  A metallic magnetic particle (10) and an insulating coating (20) including at least one selected from the group consisting of aluminum oxide, zinc oxide and zinc oxide surrounding the surface of the metallic magnetic particle (10). Forming a compact by pressurizing a plurality of composite magnetic particles (30);  And D. performing a first heat treatment on the molded body at atmospheric pressure and at a temperature of 400 ° C. or more and 900 ° C. or less. [4] The method further comprising the step of pressurizing the molded body after the first heat treatment, and thereafter performing a second heat treatment at a temperature of 400 ° C. or more and 900 ° C. or less at atmospheric pressure. The method for producing a soft magnetic material according to claim 3.