JP5145923B2 - Composite magnetic material - Google Patents

Description

  The present invention relates to a composite magnetic material having excellent productivity and magnetic properties used for various inductance components, and a method for manufacturing the same.

  A dust core used as a magnetic core for an inductance component or the like is a magnetic core manufactured by press-molding a mixed powder obtained by appropriately adding a binder such as a resin to a metal powder. The structure of the dust core is characterized in that the core loss in a high frequency region is smaller than that of an iron core using an electromagnetic steel sheet by using a resin having excellent insulating properties as a binder. Moreover, since the magnetic body which comprises comprises using metal magnetism, there exists the characteristic that a saturation magnetic flux density becomes higher than a soft ferrite core.

  However, the core loss of the dust core is still larger than that of soft ferrite, and further reduction in loss is required.

Conventionally, various manufacturing methods for dust cores have been studied for the purpose of reducing core loss. For example, a coating made by mixing and stirring a silicon resin and an inorganic pigment is sprayed and coated on the surface of the metal magnetic powder, the metal magnetic powder having an insulating film is pressure-molded, and the resulting molded body is heat-treated. The manufacturing method of the dust core obtained by this is disclosed (for example, refer patent document 1).
JP 2003-303711 A

  However, in the conventional configuration, when a hard metal magnetic powder such as Fe-Si-based and Fe-Si-Al-based plastic deformability is low, the strength of the molded body after the heat treatment is not yet sufficient and complicated. It has the subject of the yield fall at the time of mass production of the powder magnetic core which has a shape.

  In the present invention, when hard metal magnetic powders such as Fe-Si and Fe-Si-Al are used, the molded body has high strength even after heat treatment, thereby improving productivity and having excellent magnetic properties. It is an object of the present invention to provide a composite magnetic material having the above and a method for producing the same.

In order to solve the above-described conventional problems, the present invention provides a composite magnetic material comprising a metal magnetic powder, an insulating metal oxide, and an organic binder, wherein the surface of the metal magnetic powder is a partial surface. manner so as to expose, and is covered with a mesh-like or dot-like on the metal oxide Rutotomoni, wherein the sintered wearing organic binder, the coating thickness of the metal oxide is B, the metal magnetic powder When the particle diameter of A is A, the coating thickness of the metal oxide is in the range of 0.01 ≦ B / A ≦ 0.1 .

  The composite magnetic material and the method for producing the same of the present invention provide a composite magnetic material having a high strength and a good magnetic property after the heat treatment, and a method for producing the same.

(Embodiment 1)
Hereinafter, the composite magnetic material and the manufacturing method thereof according to Embodiment 1 of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view for explaining the fine structure of the composite magnetic material according to Embodiment 1 of the present invention. FIG. 2 is an enlarged cross-sectional view of the main part of FIG.

  1 and 2, reference numeral 1 denotes a magnetic metal magnetic powder, and a magnetic material having a high saturation magnetic flux density and a large magnetic permeability is preferable. The surface of the metal magnetic powder is covered with the metal oxide 2 so that the surface of the metal magnetic powder 1 is partially exposed. For example, the metal oxide 2 is formed in a mesh shape or a dot shape. It is preferable to coat with. About the metal oxide 2 which coat | covers this metal magnetic powder 1, it is preferable that it has high insulation and high joint strength, and also has excellent coating properties.

  And the composite magnetic material is comprised by carrying out fluid filling of the organic binder 3 in the clearance gap which is micro space. The metal magnetic powder 1 partially covered with the metal oxide 2 becomes particles having innumerable irregularities on the surface, and the metal magnetic powder 1 having such a surface shape has a bonding strength with the organic binder 3. It turns out that it grows.

  In addition, since the metal oxide 2 and the organic binder 3 have insulating properties, direct contact with the metal magnetic powder 1 can be prevented, and a composite magnetic material excellent in magnetic characteristics can also be prevented. Can be realized. This is particularly characterized in that the organic binder 3 is filled in contact with both the metal magnetic powder 1 and the metal oxide 2. As a result, a composite magnetic material that can increase the bond strength of the organic binder 3 and retain the mechanical strength even after heat treatment can be realized. In particular, in an inductance component that requires a complicated core shape, it is possible to provide a composite magnetic material that does not cause structural defects such as chipping and cracking even in the course of production.

  Next, the composite magnetic material in Embodiment 1 will be described in further detail.

  As the metal magnetic powder 1 used for the composite magnetic material in the first embodiment, when a hard metal magnetic material such as Fe-Si, Fe-Si-Al, Fe-based amorphous, Co-based amorphous or the like is used, magnetic characteristics are obtained. Can achieve high magnetic permeability and saturation magnetic flux density, and the effect of improving the strength of the composite magnetic material is most remarkable.

  In addition, the average particle size of the metal magnetic powder in the first embodiment is preferably in the range of 10 to 100 μm. If the average particle size is smaller than 10 μm, the magnetic permeability decreases due to a decrease in molding density, which is not preferable. Further, if the average particle size is larger than 100 μm, eddy current loss in the high frequency region increases, which is not preferable.

Moreover, as the metal oxide 2 having insulating properties, it is preferable to include at least one of inorganic substances such as Al ₂ O ₃ , SiO ₂ , MgO, ZrO, CaO, and TiO ₂ . These metal oxides 2 are less likely to react with the metal magnetic powder 1 in the course of temperature treatment such as heat treatment or annealing treatment, and are more effective as insulating materials. Moreover, it is easy to obtain a powder having a desired particle size.

  And it is preferable to coat | cover the metal magnetic powder 1 on the surface with the metal oxide 2 in 35 to 90% of range. If this coverage is less than 35%, it is not preferable from the viewpoint of magnetic properties. This is because eddy current loss due to contact between metal magnetic powders 1 or thermal diffusion increases. On the other hand, if the coverage is greater than 90%, the magnetic permeability decreases and the strength of the molded body decreases, which is not preferable.

  The thickness B of the coating layer of the metal oxide 2 partially coated on the surface of the metal magnetic powder 1 is 0.01 ≦ B / A ≦ 0.1, where A is the particle size of the metal magnetic powder. It is preferable that When B / A is smaller than 0.01, eddy current loss in the high frequency region increases, which is not preferable. On the other hand, if B / A is greater than 0.1, the density of the molded body is lowered and the magnetic permeability is lowered.

  Furthermore, as the organic binder 3, it is preferable to use a resin having insulating properties, bonding strength and heat resistance, and in particular, a silicon resin, an epoxy resin, a phenol resin, a butyral resin, a vinyl chloride resin, a polyimide resin or a polyamide resin. It is preferable to use the organic binder 3 containing at least one kind of the resin.

  Next, the manufacturing method of the composite magnetic material in this Embodiment 1 is demonstrated.

  The composite magnetic material according to the first embodiment can be improved in the strength of the compact of the composite magnetic material by being produced by the following steps.

  First, the surface of the metal magnetic powder 1 is partially coated with the metal oxide 2 in a mesh or dot shape, and then the organic binder 3 is added and mixed, followed by pressure molding and heat treatment to obtain a molded body. The molded body produced through such a process can form an infinite number of uneven portions of the metal oxide 2 formed on the surface of the metal magnetic powder 1, and an organic binder is formed on the uneven portions. When 3 invades, the anchor effect can be exhibited and the strength of the compact as a composite magnetic material can be improved. Next, examples will be described in detail.

Example 1
As the metal magnetic powder 1 used in this example, an Fe—Si—Al based sendust alloy is used, the composition of which is Si: 9%, Al: 5%, the balance Fe, and the Fe—Si based alloy , Si; 3.5%, balance Fe, and atomized powder having the average particle size shown in (Table 1). An Fe-based amorphous powder is an Fe—Si—B alloy, and a Co-based amorphous powder is a Co—Fe—Nb—B alloy prepared by liquid quenching and then pulverized to obtain an average particle size of about 50 μm. Metallic magnetic powder 1 was obtained. Moreover, as the metal oxide 2 having insulating properties, those having an average particle diameter of 5 μm or less were used.

  Next, the surface of the metal magnetic powder 1 was coated with the metal oxide 2 shown in (Table 1) in a mesh shape so as to have a predetermined coverage using a mechano-fusion method. The coverage was basically 80%.

  Here, the mechanofusion method is a technique for causing a mechanochemical reaction by applying mechanical energy between a plurality of different material particles. Examples of the apparatus used for such a mechanofusion method include a mechanofusion system manufactured by Hosokawa Micron and a hybridization system manufactured by Nara Machinery Co., Ltd.

  Next, using a mechanofusion method, a polyamide resin as an organic binder 3 on a metal magnetic powder 1 coated with a metal oxide 2 in a network form; an organic vehicle dissolved using an organic solvent so as to be 3 parts by weight After the addition, mixing and stirring were performed to prepare a mixture.

  Then, after deaeration drying was performed in order to remove the organic solvent from the mixture, the mixture after this deaeration drying was granulated with a roll granulator to produce granulated powder.

Next, this granulated powder is press-molded for 5 seconds with a pressing force of 10 ton / cm ² using a uniaxial molding machine and a predetermined mold, and the outer shape: 14 mmφ, inner diameter: 10 mmφ, thickness: about 4.5 mm A toroidal shaped body was obtained. Further, a flat molded sample for measuring the mechanical strength of height: 1.8 mm, depth: 5.85 mm, width: 50 mm by press molding at a pressure of 3.5 ton / cm ² for 5 seconds. Got.

  Then, each produced molded object was heat-processed in 300 degreeC and the temperature holding time for 0.5 hour in nitrogen atmosphere.

  A toroidal core and a plate-shaped molded body sample were produced by the combination of the metal magnetic powder 1 and the metal oxide 2 as shown in (Table 1) by the configuration and the manufacturing method as described above. The magnetic permeability and core loss (core loss) of the obtained toroidal core molded body sample were measured. The magnetic permeability (μi) was measured with a LCR meter at a frequency of 100 kHz, and the core loss was measured with a BH analyzer at a frequency of 100 kHz and a magnetic flux density of 25 mT.

  Moreover, the three-point bending test which is a measuring method of bending strength was done using the flat-shaped molded object sample, and the maximum bending stress was calculated | required. Specifically, a flat shaped sample is supported from below by two wedge-shaped support portions each having an interval of 30 mm, and a load is applied from above to the middle portion of the two support portions, and the sample is broken. The weight was measured. This bending test result was evaluated as mechanical strength. The evaluation results are shown in (Table 1).

From the results of (Table 1), Al ₂ O ₃ , SiO ₂ , MgO having insulating properties are formed on the surface of the metal magnetic powder 1 such as Fe—Si, Fe—Si—Al, Fe-based amorphous, and Co-based amorphous. It can be seen that coating the metal oxide ₂ of ZrO, CaO, and TiO ₂ partially has an effect of improving the strength of the compact as a composite magnetic material. Compared with the case where the insulating film made of the metal oxide 2 is not formed, the mechanical strength is three times or more.

Next, SiO ₂ was coated to a coverage of 70% by the same method as described above using the metal magnetic powder 1 having an average particle size as shown in (Table 2). The evaluation results of this sample are shown in (Table 2).

  From the results of (Table 2), it can be seen that a composite magnetic material having more excellent magnetic properties and compact strength is realized when the average particle size of the metal magnetic powder 1 is in the range of 10 to 100 μm.

  In the mixed powder containing at least one or more of hard metal ferromagnets such as Fe-Si, Fe-Si-Al, Fe-based amorphous and Co-based amorphous metal magnetic powders as the metal magnetic powder 1 Needless to say, there is a similar effect.

Further, as the metal oxide ₂ , the inorganic oxide powders of Al ₂ O ₃ , SiO ₂ , MgO, ZrO, CaO, and TiO ₂ have high insulating properties and are difficult to react with the metal magnetic powder 1 in the heat treatment process. Therefore, it is particularly preferable.

(Example 2)
Using the same method as in Example 1, SiO ₂ was used as the metal oxide 2 for the metal magnetic powder 1 shown in Table 3, and the coverage of the metal oxide 3 on the metal magnetic powder 1 and the metal magnetic powder 1 The relationship between the size and shape ratio was evaluated.

  Regarding the size / shape ratio, when the average particle size is A and the thickness of the coating layer of the metal oxide 2 is B, the ratio between the average particle size and the thickness of the coating layer is evaluated by B / A as the size / shape ratio. . In the production of such a sample, the metal magnetic powder 1 coated with a predetermined metal oxide 2 can be produced by changing various conditions of the mechanofusion method.

In addition, as a method for evaluating that the thickness B of the coating layer of SiO ₂ coated on the surface of the metal magnetic powder 1 is formed at a predetermined ratio with respect to the particle diameter A of the metal magnetic powder 1, After the cut surface of the sample was polished, the cross section was confirmed by a scanning electron microscope (SEM). The evaluation results for these samples are shown in (Table 3).

  From the results of (Table 3), it can be seen that a composite magnetic material capable of achieving both magnetic properties and compact strength when the coverage of the metal oxide 2 is 35 to 90% is realized.

  Further, when the ratio (A / B) of the average particle diameter A of the metal oxide 2 and the thickness B of the coating layer of the metal oxide 2 is in the relationship of 0.01 ≦ B / A ≦ 0.1, the magnetic characteristics It has been found that the strength of the molded body can be achieved.

(Example 3)
Fe-9Si-5Al sendust powder with an average particle diameter of 50 μm is used for the metal magnetic powder 1, SiO ₂ with an average particle diameter of 0.5 μm is used for the metal oxide 2, and the organic binder is shown in (Table 4). A thing was used.

  In addition, conditions other than the above were performed in the same manner as in Example 1, and samples were produced and evaluated.

That the thickness B of the coating layer of SiO ₂ coated on the surface of the sendust powder was formed with 0.01 ≦ B / A ≦ 0.1 with respect to the particle size A of the metal magnetic powder 1, the scanning type It confirmed with the electron microscope (SEM).

  The evaluation results are shown in (Table 4).

  From the results of (Table 4), when the organic binder 3 is a silicon resin, epoxy resin, phenol resin, butyral resin, polyimide resin or amide resin, a composite having more excellent magnetic properties and molded body strength. It has been found that a magnetic material can be obtained.

  In addition, when the said organic binder 3 was not added, the molded object could not be produced because mechanical strength was insufficient.

Example 4
As the metal magnetic powder 1, an atomized powder having a composition of Fe-3.5Si and an average particle diameter of 50 μm was used. The surface of the metal magnetic powder 1 was coated with colloidal silica having an average particle diameter of 1 μm as the metal oxide 2 having insulating properties.

  After colloidal silica; 20% aqueous solution was sprayed on the metal magnetic powder 1, it was dried at 150 ° C. in a nitrogen atmosphere for 2 hours. The colloidal silica thus coated on the surface of the metal magnetic powder 1 can be coated on the surface of the metal magnetic powder 1 in a mesh shape.

  An organic vehicle dissolved in an organic solvent so as to contain 3 parts by weight of a polyamide resin as an organic binder 3 was added to the metal magnetic powder 1 thus prepared, and mixed and stirred, under the same conditions as in Example 1. Then, deaeration drying and granulation were carried out to produce molded bodies such as toroidal cores and flat plate samples, and heat treatment was performed.

  In addition, it is scanned that the thickness B of the silica coating layer coated on the surface of the metal magnetic powder 1 is 0.01 ≦ B / A ≦ 0.1 with respect to the particle size A of the metal magnetic powder 1. This was confirmed by a scanning electron microscope (SEM). The evaluation results are shown in (Table 5).

  From the results of (Table 5), it was confirmed that spraying of mechanofusion and colloidal silica aqueous solution was suitable as a technique for coating the surface of the metal magnetic powder 1 with the metal oxide 2 partially and uniformly.

  As described above, the composite magnetic material and the manufacturing method thereof according to the present invention can maintain the mechanical strength as a molded body and can realize a composite magnetic material having excellent magnetic properties. It is useful as a dust core to be used.

Sectional drawing for demonstrating the fine structure of the composite magnetic material in Embodiment 1 of this invention 1 is an enlarged cross-sectional view of the main part of FIG.

Explanation of symbols

1 Metallic magnetic powder 2 Metal oxide 3 Organic binder

Claims (6)

Metal magnetic powder,
An insulating metal oxide;
A composite magnetic material comprising an organic binder,
Wherein as metal magnetic powder surface is partially exposed and covered by reticulated or dots on the metal oxide Rutotomoni are sintered wearing the organic binder,
Composite magnetism wherein the metal oxide coating thickness is in the range of 0.01 ≦ B / A ≦ 0.1, where B is the metal oxide coating thickness and A is the particle size of the metal magnetic powder. material. 2. The metal magnetic powder according to claim 1, wherein the metal magnetic powder includes at least one or more of Fe—Si, Fe—Si—Al, Fe-based amorphous, and Co-based amorphous ferromagnetic materials. Composite magnetic material. The composite magnetic material according to claim 1, wherein the metal magnetic powder has an average particle size of 10 to 100 μm. The composite magnetic material according to the metal oxide _{Al 2 O 3, SiO 2,} MgO, ZrO, to claim 1 in which the said metal oxide comprising at least one of CaO or TiO _2. The composite magnetic material according to claim 1, the surface of the magnetic metal powder coated with a range of 35 to 90% by the metal oxide. The organic binder, silicone resin, epoxy resin, phenol resin, butyral resin, vinyl chloride resin, of polyimide resin or polyamide resin, to claim 1 where the comprising at least one said organic binder The composite magnetic material described.

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