JP4569066B2 - Soft magnetic material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a soft magnetic material having a high electric resistance value that can be applied to applications requiring high AC magnetic characteristics, and in particular, a magnetic path forming member represented by a motor core (rotor core, stator core, etc.). The present invention relates to a soft magnetic material used as a material.
[0002]
[Prior art]
As such a conventional high-resistance soft magnetic material, there is a sintered soft magnetic material composed of 3 to 7% chromium, 2.5 to 3.5% silicon, and the balance iron (for example, patent) Reference 1). The sintered soft magnetic material is produced by mixing chromium and iron alloy powder with iron powder to form a raw material powder, and molding and sintering the raw material powder.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 7-179983 (Pages 2 and 3, Table 1)
[0004]
[Problems to be solved by the invention]
However, in order to improve the sinterability, it is required to make the particle size of the alloy powder / iron powder as small as possible. However, if this requirement is met, the formability deteriorates and the sintered soft magnetic material The problem that the strength is insufficient is foreseen. Incidentally, in the above-mentioned Patent Document 1, it is clearly stated that the sintered soft magnetic material is excellent in electric resistance value, magnetic flux density and coercive force, but the strength is silent.
[0005]
Therefore, an object of the present invention is to provide a high-resistance soft magnetic material having sufficient strength.
[0006]
[Means for Solving the Problems]
The means taken to solve the problem described above, as in claim 1, wherein, in the "weight ratio, C and 2.0 to 3.5%, the Si 3 .0 to 5.5% and B The remaining Fe is contained in an amount of 0.03 to 0.10%, and the matrix is composed of a ferrite-based Fe-based matrix containing Si , and the Fe-based matrix is spherical using a spheroidizing agent containing Mg and Ca. -Modified spherical graphite, compact vermicula graphite (CV), and a soft magnetic material in which boron or a boron compound is dispersed, wherein one third of the weight percent of C and the weight percent of Si in the soft magnetic material (CE value) is 2 or more, and the boron or boron compound constitutes a “soft magnetic material that exists in the matrix structure and at the grain boundaries of the matrix structure”.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In order to describe the present invention in more detail, examples are given below together with comparative examples, but the present invention is not limited to these examples.
[0008]
Production method:
High purity pig iron (C content 4.0 wt%) 6Kg, S25C19Kg, carburizing agent (C content 70wt%) 680g, ferrosilicon (Si content 70wt%) 1150g and boron source are put in a high frequency furnace and melted And this dissolution is used as a hot spring.
[0009]
In the crucible for spheroidizing treatment, spheroidizing agent (TDCR-5 / Mg: 4.8 wt%, Si: 46 wt%, Ca: 2.4 wt%, balance: Fe / particle size: 20 mm) manufactured by Toyo Denka, 70 g of ferrosilicon (Si-containing 70 wt%, balance: Fe) is added, and 110 g of iron powder is covered thereon.
[0010]
Into the spheroidizing crucible, the hot water dissolved up to 1600 ° C. is poured to cause the spheroidizing reaction. Thereafter, the melted material after the spheroidizing treatment is poured into a self-hardening sand mold (using alkali phenol as a binder). The pouring temperature is 1450 ° C., and at the time of pouring, carballoy (Fe-Si system) made by Osaka Special Alloy is used, and pouring is inoculated.
[0011]
After 1 hour from pouring, the sand casting is taken out of the sand mold.
[0012]
In addition, the sand mold (casting mold) used was a mold shape that could take a test piece for measuring material magnetic properties and electrical resistance and an iron core for motor properties.
[0013]
composition:
According to the above method, 2.0% C, 3.0% Si and 0.07% B are included by weight, and the balance is Fe, and spherical graphite and compact vermicular graphite (CV graphite) are contained in the matrix. A soft magnetic material having) was obtained.
[0014]
Organization:
FIG. 2 shows a photomicrograph of a soft magnetic material having such a composition. As shown in this photograph, in the structure of the soft magnetic material of Example 1, CV-like graphite and spherical graphite are dispersed in the matrix structure, and boron compounds are precipitated in the grain boundaries and the matrix structure. . Since the matrix is a ferritic iron-based matrix containing silicon, the soft magnetic characteristics of the matrix portion are excellent. The electrical resistance is higher due to CV-like graphite, spheroidal graphite, and boron compound dispersed in the matrix. The strength can ensure the tensile strength by carrying out the spheroidization treatment.
[0015]
Characteristic:
The magnetic properties (magnetic flux density / effective permeability), volume resistivity, and tensile strength of the soft magnetic material having the composition and structure described above were measured. The magnetic properties were measured using a BH analyzer SY-8232 with Iwasaki Tsushinki Co., Ltd. under the conditions of an AC frequency of 400 Hz and a magnetic field of 2000 A / m, and the electrical resistance was measured by the 4-terminal method. went. Moreover, the tensile strength was performed using the JIS Z2201 No. 4 test piece according to the conditions of JIS Z2241. The results are shown in FIG. 1 and all show excellent characteristics.
[0016]
<Example 2>
In a weight ratio, C is 2.3%, Si is 3.4%, and B is 0.03%, the balance is Fe, and the base has spherical graphite and compact vermicula graphite. A magnetic material was produced in the same manner as in Example 1. The soft magnetic material according to Example 2 had the characteristics shown in FIG. The measurement of characteristics is the same as the measurement procedure in the first embodiment.
[0017]
<Example 3>
In a weight ratio, C is 3.5%, Si is 5.0% and B is 0.05%, the balance is Fe, and the base has spheroidal graphite and compact vermicular graphite. A magnetic material was produced in the same manner as in Example 1. The soft magnetic material according to Example 3 had the characteristics shown in FIG. The measurement of characteristics is the same as the measurement procedure in the first embodiment.
[0018]
<Example 4>
In a weight ratio, C is 3.5%, Si is 5.0% and B is 0.10%, the balance is Fe, and the base has spherical graphite and compact vermicular graphite. A magnetic material was produced in the same manner as in Example 1. The soft magnetic material according to Example 4 had the characteristics shown in FIG. The measurement of characteristics is the same as the measurement procedure in the first embodiment.
[0019]
<Example 5>
The weight ratio includes 3.5% C, 5.5% Si, and 0.10% B, the balance is Fe, and the base has spherical graphite and compact vermicula graphite. A magnetic material was produced in the same manner as in Example 1. The soft magnetic material according to Example 5 had the characteristics shown in FIG. The measurement of characteristics is the same as the measurement procedure in the first embodiment.
[0020]
<Comparative Example 1>
A soft magnetic material was prepared from an iron powder molded body containing a resin content of 0.6% by weight. The soft magnetic material according to Comparative Example 1 has the characteristics shown in FIG. The measurement of characteristics is the same as the measurement procedure in the first embodiment.
[0021]
<Comparative Example 2>
A soft magnetic material was produced from a 3% silicon steel plate having a thickness of 3 mm. The soft magnetic material according to Comparative Example 2 has the characteristics shown in FIG. The measurement of characteristics is the same as the measurement procedure in the first embodiment.
[0022]
<Comparative Example 3>
A soft magnetic material containing 2.0% C and 4.0% Si, the balance being Fe, and having spherical graphite in the matrix in the same manner as in Example 1 in a weight ratio. Produced.
The soft magnetic material according to Comparative Example 3 has the characteristics shown in FIG. The measurement of characteristics is the same as the measurement procedure in the first embodiment.
[0023]
<Comparative example 4>
In a weight ratio, a soft magnetic material containing 2.3% of C and 3.4 of Si, the balance being Fe, and having spherical graphite in the matrix was obtained in the same manner as in Example 1. Produced. The soft magnetic material according to Comparative Example 4 has the characteristics shown in FIG. The measurement of characteristics is the same as the measurement procedure in the first embodiment.
[0024]
<Overview of Examples and Comparative Examples>
In the soft magnetic material of each example, CV-like graphite and spherical graphite are dispersed in the matrix structure, as is apparent from the evaluation results in the table of FIG. In a ferritic iron-based matrix containing). As a result, the material properties of volume resistivity, magnetic properties, and strength necessary for the motor core can be secured in a well-balanced manner. Since the soft magnetic material of each example is a material that can be cast and has this material property, it is possible to produce a core having a three-dimensional shape that is not possible with a silicon steel plate. Moreover, since the soft magnetic material of each Example is a soft magnetic material with high intensity | strength, it becomes possible to use in the motor operation | movement conditions which generate | occur | produce the high-torque in the press injection of the shaft which cannot be performed with an iron powder molded body, and a high temperature environment. .
[0025]
The soft magnetic material of each embodiment can be used as a magnetic path forming material for electromagnetic actuators such as motors and electromagnetic valves. For motors, it can be used for rotor cores, stator cores, and the like. As the motor, various motors such as an ABS system motor, a power steering motor, a wiper motor, a window regulator motor, a door lock motor, and a sunroof motor can be used. Since the soft magnetic material according to the present invention is made by melting, there is little change in strength and magnetic characteristics even in a high temperature environment or an environment with temperature change. Can be used.
[0026]
【The invention's effect】
According to the present invention, there is a great practical effect that a soft magnetic material having high resistance and high strength can be obtained.
[Brief description of the drawings]
FIG. 1 is a graph showing characteristics of an embodiment of the present invention and a comparative example thereof.
FIG. 2 is a photomicrograph showing the structure of a soft magnetic material according to Example 2 of the present invention.

Claims (1)

By weight, C is 2 . 0 to 3.5%, the Si 3. 0 to 5.5%, B is 0.03 to 0.10% and the balance is Fe. The matrix is composed of a ferrite-based Fe-based matrix containing Si , and Mg and Ca are contained in the Fe-based matrix. A soft magnetic material in which spherical graphite, compact vermicula graphite (CV), and boron or a boron compound dispersed therein using a spheroidizing treatment agent are contained, wherein the weight percentage of C in the soft magnetic material is A soft magnetic material in which the sum (CE value) of 1/3 by weight of Si is 2 or more, and the boron or boron compound is present in the matrix structure and at the grain boundary of the matrix structure.

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