JP2003086415A - Soft magnetic particle for motor of electromagnetic actuator, manufacturing method therefor, soft magnetic molded body for motor or electromagnetic actuator, and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide soft magnetic particles for motor or electromagnetic actuator, which are advantageous to increase the resistivity of a motor or electromagnetic actuator, while increasing the permeability of the motor or actuator, a method of manufacturing the particles, a soft magnetic molded body for motor or electromagnetic actuator, and a method of manufacturing the molded body. SOLUTION: The soft magnetic particles are manufactured by coating iron powder and particles, containing iron as the main component with soft ferrite layers. A step of reducing the number of crystal grains can be performed as necessary on the iron powder and particles. In the method of manufacturing soft magnetic particles for motor or electromagnetic actuator, a step of preparing powder aggregates containing the soft magnetic particles for motor or electromagnetic actuator as main component and a coupling step of obtaining the soft magnetic molded body, by coupling the aggregates with each other through press-molding the aggregates are performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing soft magnetic particles used in a soft magnetic core equipped in an AC-driven motor or an electromagnetic actuator, a soft magnetic compact and a method for producing the soft magnetic compact. .

[0002]

2. Description of the Related Art With recent advances in industrial equipment and the like, soft magnetic materials are required to have higher magnetic permeability than ever before. Further, in addition to high magnetic permeability, it is required to have high specific resistance in order to reduce iron loss and the like.
To meet these demands, various studies have been conducted so far, and various soft magnetic molded body technologies have been proposed.

In Japanese Unexamined Patent Publication No. 5-326289, Fe is disclosed.
-Soft magnetic particles in which the surface of the powder particles is selectively oxidized by heat-treating an Al-based iron-based powder in the air to form a film of aluminum oxide or iron oxide having a high specific resistance on the surface of the powder particles. Is disclosed, and a powder aggregate of the soft magnetic particles is molded under high temperature and high pressure to manufacture a high-density magnetic core.

In Japanese Patent Laid-Open No. 5-47541, the surface of the soft magnetic metal particles is obtained by mechanically agitating the soft magnetic metal particles and the soft ferrite in a drum while mechanically stirring them. Discloses a technique for producing a magnetic core by mechanically coating a soft ferrite layer and plasma-activating sintering a powder aggregate of the soft magnetic metal particles.

In Japanese Unexamined Patent Publication (Kokai) No. 8-167519, the surface of soft magnetic metal powder particles is coated with a glassy oxide having a high specific resistance, and the powder aggregate of the soft magnetic metal powder particles is heated at a high temperature. A technique for manufacturing a soft magnetic compact by high pressure sintering is disclosed.

Japanese Unexamined Patent Publication No. 9-180924 discloses that Si
A technique is disclosed in which metal powder particles are covered with an insulating layer containing oxide fine particles made of O _2, and the metal powder particles are bonded to each other through the insulating layer to manufacture a soft magnetic compact.

[0007]

According to the above-mentioned respective prior arts, since the specific resistance of the soft magnetic molded body can be increased, the vortices generated in the soft magnetic molded body even when used in an alternating magnetic field. The current can be suppressed, and eventually the loss can be suppressed by the eddy current. However, although the above-mentioned respective prior arts have satisfactory specific resistance values, they have not always been satisfactory with respect to the magnetic permeability value of the soft magnetic molded body. In particular, the soft magnetic particles and soft magnetic moldings used for the stator core and rotor core installed in motors,
The value of magnetic permeability was not always sufficient.

According to the technique disclosed in the above-mentioned Japanese Patent Laid-Open No. 5-47541, by carrying out mechanofusion by mechanically agitating soft magnetic metal particles and soft ferrite in a drum. The surface of the soft magnetic metal particles is mechanically coated with a soft ferrite layer, but in this case, stress distortion occurs in the soft magnetic metal particles due to mechanical agitation, and the expected magnetic characteristics are It is disadvantageous to obtain. Furthermore, when the surface of the soft magnetic metal particles is coated with a soft ferrite layer by mechanofusion, a minute gap is often generated at the boundary between the soft magnetic metal particles and the soft ferrite layer. This may cause a decrease in magnetic permeability.

The present invention has been made in view of the above-mentioned circumstances, and is soft magnetic particles for a motor or an electromagnetic actuator, which is advantageous for increasing the magnetic permeability while increasing the specific resistance, and soft magnetic for a motor or an electromagnetic actuator. A method for producing particles,
An object of the present invention is to provide a soft magnetic molded body for a motor or an electromagnetic actuator, and a method for manufacturing a soft magnetic molded body for a motor or an electromagnetic actuator.

[0010]

The inventor of the present invention is eagerly developing a technique relating to soft magnetic particles and soft magnetic moldings used in motors and electromagnetic actuators. And
By coating the surface of iron powder particles containing iron as the main component with a soft ferrite layer by ferrite plating, it is possible to increase the magnetic permeability while increasing the specific resistance, and moreover, between the surface of the iron powder particles and the soft ferrite layer. The gap that is the main cause of the magnetic gap of can be reduced or eliminated, and when used in applications in which an alternating magnetic field acts, it is possible to reduce eddy currents, which is advantageous in reducing losses due to eddy currents. The present invention was completed by confirming the above and confirming by a test.

That is, the soft magnetic particles for motors or electromagnetic actuators according to the present invention are characterized in that iron powder particles containing iron as a main component are coated with a soft ferrite layer by ferrite plating on the surface. is there.

The method for producing soft magnetic particles for a motor or electromagnetic actuator according to the present invention comprises the steps of preparing iron powder particles containing iron as a main component, and coating the surface of the iron powder particles with a soft ferrite layer by ferrite plating. And a coating step to do so.

A soft magnetic compact for a motor or an electromagnetic actuator according to the present invention is characterized in that powder aggregates containing the soft magnetic particles according to any one of claims 1 to 7 as main elements are bonded to each other. It is what

A method of manufacturing a soft magnetic compact for a motor or an electromagnetic actuator according to the present invention comprises a step of preparing a powder aggregate having soft magnetic particles as a main element according to any one of claims 1 to 7, And a binding step of obtaining a soft magnetic molded body by press-molding a powder aggregate of the soft magnetic particles and bonding them to each other.

The soft ferrite layer is basically a composite oxide layer having iron oxide as a main component and having a high insulating property, and has a high specific resistance and a high magnetic permeability. Therefore, if the surface of the iron powder particles containing iron as a main component is coated with the soft ferrite layer, it is advantageous for exhibiting high specific resistance and high magnetic permeability. Therefore, when used in an application in which an alternating magnetic field such as a high frequency alternating magnetic field acts, the eddy current is reduced and the loss caused by the eddy current is reduced.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The iron powder particles according to the present invention include:
Pure iron (Fe), iron-aluminum system (Fe-Al system),
Iron-silicon type (Fe-Si type), iron-nickel type (F
e-Ni system), iron-silicon-aluminum (Fe-S)
At least one of i-Al system), iron-chromium system (Fe-Cr system), and iron-cobalt system (Fe-Co system) can be adopted, and it may be amorphous in some cases. In the iron powder particles, C is 0.1% or less by weight, and especially C.
It can be up to 01% and O can be up to 0.5%, in particular up to 0.1%. As iron powder particles,
It may be produced by the water atomizing method, may be produced by the gas atomizing method, or may be produced by the mechanical crushing method in some cases.

If the particle size of the iron powder particles is excessively small, it is difficult to obtain a satisfactory magnetic synchronism. When the particle size of the iron powder particles is excessively large, the compression moldability is deteriorated when the soft magnetic molded body is compression molded. Therefore, the particle size of the iron powder particles is 10 μm
2000 μm, 10 μm to 1000 μm, preferably 5
0 to 250 μm, more preferably 100 μm to 200 μm
m can be adopted. Iron powder particles having a uniform particle size can be used. To increase the density of the soft magnetic compact, use iron powder particles with a large particle size and iron powder particles with a small particle size together rather than using iron powder particles with a uniform particle size. You can also

As the soft ferrite layer, a spinel type structure can be generally adopted. Since the spinel structure has a relatively small crystal magnetic anisotropy, it has high magnetic permeability and high saturation magnetic flux density. In this case, as the soft ferrite layer, (Fe,
M) A form having a composition formula of ₃ O ₄ can be adopted. M is iron (F
e), cobalt (Co), nickel (Ni), manganese (Mn), zinc (Zn), chromium (Cr), aluminum (Al), and titanium (Ti). When the above M is Ni or Zn, Ni
Also called Zn soft ferrite. The thickness of the soft ferrite layer depends on the size of the plating particles, the composition of the soft ferrite layer, the particle size of the iron powder particles, etc., but is 0.01 μm.
-10 μm, especially 0.01 μm-2 μm, 0.2 μm-
It can be 1 μm. When the thickness of the soft ferrite layer is excessive, it takes a long time to form the soft ferrite layer, which is not preferable in terms of industrial production. If the thickness of the soft ferrite layer is too small, it becomes difficult to obtain the desired specific resistance of the soft magnetic particles and the soft magnetic molded body, and when used in an alternating magnetic field, there is a possibility that the loss caused by the eddy current will increase.

The soft ferrite layer is coated with iron powder particles by ferrite plating. In this case, the soft ferrite layer may be coated on the entire surface or substantially the entire surface of the iron powder particles, and in some cases, in consideration of the bondability between the iron powder particles, on the surface of the iron powder particles. It may be a partially covered form. Ferrite plating is a plating method for producing a soft ferrite layer containing iron oxide having ferromagnetism and insulation as a main component from a solution such as an aqueous solution at low temperature (generally 20 to 120 ° C.). By contacting the iron powder particles with the iron powder particles, the soft ferrite layer can be coated on the iron powder particles.

As the plating solution, an aqueous solution containing iron ions (Fe ²⁺ ) and other metal ions (M ^{n +} ) can be generally adopted. Examples of the other metal ion include at least one kind of cobalt ion, nickel ion, manganese ion, zinc ion, chromium ion, aluminum ion, and titanium ion. Iron ions (Fe ²⁺ ) and other metal ions (M ^{n +} ) are adsorbed via the OH groups on the surface of the granular material. Nitrite ion (NO ₂ ^-), presumably by introducing an oxidizing agent such as air in the plating solution, while with the oxidation reaction of Fe ²⁺ → Fe ^3+, soft ferrite layer is formed on the surface of the iron powder particles Has been done. The soft ferrite layer thus formed is generally said to have a spinel structure.

Prior to the coating step of coating the surface of iron powder particles with the soft ferrite layer according to the present invention, the iron powder particles are heated to a high temperature in a heating atmosphere to heat the number of crystal grains in one iron powder particle. It is possible to adopt a mode in which the number of crystal grains to be reduced and the step of reducing the number of steps are performed as compared with the above. In this case, it is preferable that the average number of crystal grains in one iron powder particle is 10 or less or 5 or less when viewed from the cut surface. As a result, the size of the crystal grains in the iron powder particles is increased, and the magnetic permeability of the iron powder particles is increased.
It is also possible to promote the single crystallization of iron powder particles through the above-described crystal grain number / reduction step. Single crystallization is advantageous for increasing the magnetic permeability of the soft magnetic particles.

A non-oxidizing atmosphere is preferable as a heating atmosphere for heating the iron powder particles in the crystal grain number / reducing step. Examples of the non-oxidizing atmosphere include reducing atmosphere (for example, hydrogen gas atmosphere, hydrogen gas-containing atmosphere), vacuum atmosphere, and argon gas atmosphere. In the case of a reducing atmosphere, the surface of the iron powder particles can be reduced, which is advantageous for ensuring the inherent magnetic permeability of iron, which is the main component of the iron powder particles. If the number of crystal grains and the heating temperature in the reduction process are high, it is advantageous to reduce the number of crystal grains in one iron powder particle and obtain a high magnetic permeability, but the consumed heat energy is large and the manufacturing cost is high. Will be at a disadvantage.
Therefore, as the heating temperature in the number of crystal grains / reduction process,
It is selected in consideration of factors such as particle material, required magnetic permeability, cost, etc., and generally 750 to 1350 ° C. can be adopted. Therefore, 1320 ° C., 1280 ° C., 1250 ° C. or the like can be exemplified as the upper limit of the heating temperature depending on the degree of importance of the above factors. The lower limit of heating temperature is 780 ° C, 8
Examples include 20 ° C. and 860 ° C. Considering the reduction of the number of crystal grains in one iron powder particle, the coexistence of the manufacturing cost, etc., the heating temperature is in the range of 800 to 1320 ° C., 82
0 to 1280 ° C range, 850 to 1220 ° C range, 9
The range of 00 to 1100 ° C is preferable. However, it is not limited to these. The heating time may be generally 20 minutes to 2 hours or 30 to 90 minutes, although it depends on the required magnetic permeability and heating temperature, but 10 minutes or more is preferable. Since the powder aggregate of particles has the same specific surface area as compared with the metal mass having the same weight and the same composition, the heat transfer to the inside is performed quickly, and the heating time for reducing the crystal grains is Compared with the case of heating metal lumps of the same material, it takes less time.

Even when an oxide film is formed on the iron powder particles, the oxide film formed on the iron powder particles is removed when the heating atmosphere in the step of reducing the number of crystal grains is a reducing atmosphere. A reduction can be expected, which can contribute to uniform ferrite plating. The heating method in the crystal grain number / reduction step is not particularly limited, and heat transfer heating, radiant heating, or induction heating may be performed in the heating furnace.

When the total amount of powder aggregates of soft magnetic particles is 100% by weight, or the total amount of soft magnetic compacts is 10% by weight.
When the content is 0% by weight, the number of crystal grains in one iron powder particle is not more than n on average (n = 10) when viewed from the cut surface, and 80% by weight or more of the iron powder particles, especially It preferably accounts for 90% by weight or more. Note that n = 7 can be set. Alternatively, n = 5 or n = 3 can be set.

In addition, the whole powder aggregate of soft magnetic particles is
When it is set to 00% by weight, or when the whole of the soft magnetic molded body is set to 100% by weight, the single crystallized iron powder particles are 80% by weight or more, particularly 90% by weight or more when viewed from a cut surface. The occupying form can also be adopted.

Further, if the above-described crystal grain number / reduction step is performed on the iron powder particles, the size of the crystal grains in the iron powder particles becomes large, and the hardness of the iron powder particles can be expected to decrease, so that pressure molding is performed. This facilitates compression at the time of compression and is advantageous in increasing the density of the soft magnetic molded body. In this case, it is advantageous to improve the magnetic permeability and the mechanical strength of the soft magnetic molded body.

According to the present invention, the acid contact step of contacting the iron powder particles with the acid can be carried out prior to the above-mentioned coating step. In this case, it is preferable to immerse the iron powder particles in an acid or an acid aqueous solution. The natural oxide film formed on the surface of the iron powder particles is removed by the acid contact process, and the new surface can be exposed on the surface of the iron powder particles, which is advantageous for reducing unevenness of ferrite plating that produces soft ferrite. Is. Therefore, the coating of the soft ferrite layer can be made uniform, and the unevenness of the soft ferrite layer can be reduced.
Examples of the acid used in the acid contact step include hydrochloric acid, nitric acid, sulfuric acid and the like. If the concentration of the acid is excessive, the iron powder particles will melt and the diameter of the iron powder particles will change unexpectedly, and the reaction will be too fast to control the diameter of the iron powder particles. If the acid concentration is too low, the acid contact step requires time, which is not preferable in terms of industrial production. Therefore, the concentration of the acid depends on the type of the acid and the composition of the iron powder particles, but is 0.
01 to 10% can be adopted, preferably 0.1 to 1%, 0.
5 to 0.8% (0.7%) is preferable, but not limited to these. The time of the acid contact step depends on the type of acid and the composition of the iron powder particles, but is 5 seconds to 10 minutes, especially 3 seconds.
It can be exemplified from 0 seconds to 3 minutes, but is not limited to this. When both the crystal grain number / reduction step and the acid contact step are performed, the acid contact step can be performed after the crystal grain number / reduction step.

When the acid contact step is performed after the crystal grain number / reducing step is performed in a reducing atmosphere, not only the crystal grain number / reducing step can be performed but also the iron powder particles can be reduced. It is also possible to reduce or eliminate the oxide film formed on the surface. Therefore, it is advantageous for shortening the acid contact time and for reducing the acid concentration in the acid contact step performed after the crystal grain number / reduction step.

The soft magnetic compact for a motor or electromagnetic actuator according to the present invention is formed by bonding the powder aggregates of the soft magnetic particles produced as described above to each other. In manufacturing a soft magnetic compact for a motor or an electromagnetic actuator, a step of preparing a powder aggregate having the above-mentioned soft magnetic particles as a main element, and pressing the powder aggregate of the soft magnetic particles to bond them to each other. By doing so, it is possible to carry out a bonding step of obtaining a soft magnetic molded body. Examples of the pressure molding include a molding die pressure method and a hydrostatic pressure method (CIP). The pressing force varies depending on the type of iron powder particles, the temperature of pressure molding, etc., but is 2.0 to 10 to
nf / cm ² (≈196 to 980 MPa), especially 4.5
˜7 tonf / cm ² (≈441 to 686 MPa) can be exemplified, but the invention is not limited thereto. Although the pressing time varies depending on the type of iron powder particles, the temperature of pressure molding, etc., it is 5 to 120 seconds, especially 10 seconds.
-60 seconds can be exemplified, but the invention is not limited thereto. Examples of the atmosphere for pressure molding include an air atmosphere and a non-oxidizing atmosphere (argon gas atmosphere, vacuum atmosphere, etc.).

The soft magnetic molded body can be applied to at least one of a stator core of a motor, a rotor core of a motor, and a soft magnetic core of an electromagnetic actuator. Therefore, it may be applied to a stator core of a motor, a rotor core of a motor, or a soft magnetic core of an electromagnetic actuator. The motor may be any known motor, and includes rotary motors and linear motors. The electromagnetic actuator means one that operates an operating element by a magnetic force or an electromagnetic force by energizing a coil, and includes a solenoid valve of a plunger type, a solenoid valve used in a fluid circuit such as a hydraulic circuit or a pneumatic circuit, and the like. .

[0031]

EXAMPLES Examples of the present invention will be specifically described. (First
Example) (1) A powder aggregate of iron powder particles having the following soft magnetism was prepared.

Composition: weight ratio Fe-0.004% C-
0.25% O-0.01% Si-0.01 Mn-0.0
01% P Production method: Gas atomization method Particle size: 50 to 150 μm As described above, the particle size is widely dispersed to 50 to 150 μm because the particle size is made uniform in order to increase the density of the soft magnetic molded body. This is because it is preferable to use the iron powder particles having a large particle size and the iron powder particles having a small particle size together, rather than using only the iron powder particles. It is also disadvantageous in terms of manufacturing cost. 1 and 2 are electron micrographs (TEM) of iron powder particles as a starting material produced by the gas atomizing method.
Indicates.

(2) Next, the powder aggregate of iron powder particles is heated to a high temperature (1000 ° C. × 1 hour) in a reducing atmosphere (hydrogen atmosphere) to perform the step of reducing the number of crystal grains of the iron powder particles. It was The number of crystal grains on the cut surface of one iron powder particle was 15 or more on average before heating,
After heating, it was reduced to 8 or less on average. Along with this, the size of the crystal grain was increased in one iron powder particle.

(3) Next, an acid contact step of contacting the iron powder particles subjected to the above-described crystal grain number / reduction step with an acid was carried out in a room temperature range. In this case, hydrochloric acid aqueous solution (vol%
About 0.7%) was immersed in the iron powder particles for about 10 minutes. The purpose of the acid contact step is to remove the oxide film formed on the surface of the iron powder particles. The concentration of the above-mentioned hydrochloric acid aqueous solution is not limited to the above and can be changed as appropriate as long as the oxide film formed on the surface of the iron powder particles can be removed.

(4) Ferrite plating treatment was performed on the powder aggregate of iron powder particles that had been subjected to the acid contact step described above.
As shown in FIG. 7, an oxidant supply tank 10, a processing tank 12, a plating solution supply tank 14, and an ammonia container 16 were prepared. An aqueous solution of iron chloride (3 g / 300 m
l), nickel chloride aqueous solution (0.717 g / 300 m)
1) and an aqueous zinc chloride solution (0.081 g / 300 ml) were added. An aqueous solution of sodium nitrite (1.0 g / 500 ml) was put into the oxidizing agent supply tank 10. The concentrations of the iron chloride aqueous solution, the nickel chloride aqueous solution, the zinc chloride aqueous solution, and the sodium nitrite aqueous solution are not limited to the above and can be changed as appropriate.

Then, the iron powder particles that have undergone the acid contact step are charged into the processing tank 12, and the hose 10c of the first metering pump 10a, the hose 14c of the second metering pump 14a, the ultrasonic transducer 20, and the PH. The electrode 22 was placed in the processing tank 12. After confirming that the iron powder particles in the treatment tank 12 are dispersed by the vibration action of the ultrasonic oscillator 20, the oxidant aqueous solution in the oxidant supply tank 10 is introduced into the treatment tank 12 by the first metering pump 10a. Supply and second metering pump 1
4a treats the plating liquid in the plating liquid supply tank 14 with the processing tank 1
2, and the iron powder particles were subjected to a ferrite plating treatment.

In carrying out the ferrite plating treatment, the ammonia water is treated by the titration pump 16a.
It was dripped appropriately. The supply amount per unit time was 3.0 ml / min for the plating solution, 2.0 ml / min for the oxidizing agent, and 4.3 ml / min for the ammonia water. However, it is not limited to this. In the ferrite plating treatment, the inside of the treatment tank 12 becomes acidic, so the pH was kept at 6.0 by the pH monitor. As the ferrite plating process progresses, the processing tank 1
The plating solution in 2 changed from blue green to brown to black.

The surface of the iron powder particles was coated with the soft ferrite layer by the ferrite plating treatment. After completion of the ferrite plating treatment, the iron powder particles in the treatment tank 12 were adsorbed by a magnet and taken out from the treatment tank 12. The iron powder particles taken out were transferred onto a filter paper, and the iron powder particles were filtered and washed with pure water. Further, the iron powder particles were filtered and washed with ethanol.

FIG. 8A schematically shows a conceptual diagram of the soft magnetic particles formed in this way. As shown in FIG. 8 (A),
A soft ferrite layer 200 is coated on the entire surface of the iron powder particle 100 having a large crystal grain. See also FIG.
(B) schematically shows a conceptual diagram of soft magnetic particles formed without performing the above-described crystal grain number / reduction step. As shown in FIG. 8B, in the iron powder particles 100A that have not been subjected to the crystal grain number / reduction step, many crystal grains are generated in one iron powder particle. The surface of the iron powder particles 100A is covered with the soft ferrite layer 200.

FIGS. 3 and 4 show electron micrographs (TEM) of iron powder particles after the ferrite plating treatment is performed after the acid contact step as described above. As can be seen from FIGS. 3 and 4, the ferrite layer was uniformly formed after the acid contact step. Further, FIG. 5 shows an electron micrograph (TEM) of iron powder particles after carrying out the ferrite plating treatment without carrying out the above-mentioned acid contacting step. As shown in FIG. 5, when the ferrite plating treatment is performed without performing the above-mentioned acid contact step, the surface of the iron powder particles is covered with the soft ferrite layer, but a part of the surface of the iron powder particles is covered. There was also an ungenerated portion where the soft ferrite layer was not covered. Therefore, considering the uniform coverage of the soft ferrite layer, it is preferable to perform the acid contact step on the iron powder particles before the ferrite plating treatment. However, when the oxide film has no practical problems, the acid contact step may not be performed.

(5) The powder aggregate of the soft magnetic particles thus produced was loaded into a cavity of a molding die (not shown) and then pressure-molded to carry out a bonding step of bonding the soft magnetic particles to each other. As a result, a soft magnetic compact (diameter: 30 m
m, a cylinder with a height of 10 mm) was formed. The conditions for pressure molding were warm molding (450 ° C. in the atmosphere), and the surface pressure was 7.0 tonf / cm ² (≈686 MPa).
FIG. 6 shows an optical microscope photograph (after nital etching) of the soft magnetic molded body that has been pressure-molded as described above. As shown in FIG. 6, soft magnetic particles are bonded to each other, and a soft ferrite layer is laminated around the soft magnetic particles. It can be seen that the soft ferrite layer is formed in a three-dimensional network. The density of this soft magnetic molded body was 7.4 to 7.7.

(6) The specific resistance and magnetic permeability of the soft magnetic molded body formed as described above were measured, and the relationship therebetween was determined. Regarding specific resistance, soft magnetic molded body (diameter: 30 m
m, a column having a height of 10 mm) was used and the measurement was carried out at room temperature by the four-terminal method. Regarding the magnetic permeability, the soft magnetic molded body (diameter: 3
From 0mm, height 10mm cylinder) to test piece (outer diameter 12
mm × inner diameter 8 mm × height 2 mm) was taken out, and the initial magnetic permeability μi of the test piece was measured. The measurement result is shown in FIG. In FIG. 9, the mark Δ corresponds to the developed material 1. The ○ mark corresponds to the developed material 2.

In the developed material 1, the material of the iron powder particles is pure iron (average particle size: 100 μm), and the soft ferrite layer is N.
iZn soft ferrite (thickness: about 200 nm = about 0.
2 μm). In the developed material 2, the material of the iron powder particles is pure iron (average particle size: 100 to 250 μm), and the soft ferrite layer is NiZn soft ferrite (thickness: about 200
nm = about 0.2 μm). The comparative material 1 is a technology according to the prior art 1 (Japanese Patent Laid-Open No. 5-326289) described in the prior art, in which the surface of iron powder particles is coated with an insulating film of iron oxide by selective oxidation. In Comparative Material 1, the material of the iron powder particles is Fe-3 wt% Si (average particle diameter: 100 μm), and the insulating layer is SiO ₂ (thickness: about 150 μm).
nm). The comparative material 2 is a technology according to the prior art 2 (Japanese Patent Laid-Open No. 5-47541) described in the prior art, and is a method in which the surface of iron powder particles is coated with a soft ferrite layer by mechanofusion. In Comparative Material 2, the iron powder particles were made of pure iron (average particle size: 100 μm),
Insulating layer is MnZn soft ferrite (thickness: about 2 μm)
And The comparative material 3 is a technology based on the conventional document 3 (Japanese Patent Laid-Open No. 8-167519) described in the prior art, and is a glass coating in which the surface of iron powder particles is covered with an insulating film. In Comparative Material 3, the iron powder particles were made of pure iron (average particle size: 100 μm), and the insulating layer was made of phosphate glass (thickness: about 40 nμm).

As can be understood from FIG. 9, according to the developed materials 1 and 2, it was possible to obtain a high magnetic permeability while realizing a high specific resistance. On the other hand, Comparative material 1 to Comparative material 3
The magnetic permeability was not sufficient.

(Second Embodiment) The second embodiment has basically the same configuration as that of the first embodiment, and has the same effects as the first embodiment. In the second embodiment, the molding conditions for the soft magnetic molded body are based on those of the first embodiment. In the second embodiment, the iron powder particles are not subjected to the crystal grain number / reduction step, but the iron powder particles subjected to the acid contact treatment are subjected to the ferrite plating treatment. According to the soft magnetic molded body formed by pressure-molding the soft magnetic particles manufactured in the second example, it is possible to obtain a high magnetic permeability while realizing a high specific resistance.

(Third Embodiment) The third embodiment has basically the same configuration as that of the first embodiment, and has the same effects as the first embodiment. In the third embodiment, the molding conditions for the soft magnetic molded body are based on those of the first embodiment. According to the third embodiment, the iron powder particles are subjected to the crystal grain number / reduction step, but not to the acid contact step. Therefore, the ferrite plating treatment was carried out on the iron powder particles which had been subjected to the crystal grain number / reduction step but not the acid contact step. According to the soft magnetic molded body formed by pressure-molding the soft magnetic particles manufactured in the third embodiment, it is possible to obtain a high magnetic permeability while realizing a high specific resistance. However, since the acid contact step was not carried out, the soft ferrite layer coated with the iron powder particles had some unevenness.

(Preliminary test) Prior to the production of the above-mentioned soft magnetic compact, a preliminary test was performed to select the optimum size of the iron powder particles. In this preliminary test, pure iron powder was used as the iron powder particles, a green compact was formed by warm molding, and the influence of the powder particle size was investigated. In this case, since it is a preliminary test, the pure iron powder is not plated with ferrite. The results of the preliminary test are shown in FIGS. As shown in FIG. 10, the maximum magnetic permeability before sieving was about 1000.
As shown in FIG. 10, when the particle size is 45 μm or less,
The maximum magnetic permeability was about 650. Particle size is 100-25
In the case of the range of 0 μm, the maximum magnetic permeability exceeded 1100 both in the case of the particle size of 160 to 250 μm and in the case of the particle size of 250 to 430 μm.

Further, the relationship between the powder particle size of the iron powder particles and the density of the soft magnetic compact was measured, and similarly, the relationship between the powder particle size and the magnetic flux density of the soft magnetic compact was measured. Figure 11 shows the measurement results.
Shown in. In this case, since it was a preliminary test, iron powder particles not subjected to ferrite plating were used. As the molding conditions for the soft magnetic molded body, the temperature is 450 ° C. and the applied pressure is 7 ton.
f / cm ² (≈686 MPa). In FIG. 11, the mark ◯ indicates the density of the soft magnetic molded body. Δ indicates the magnetic flux density of the soft magnetic molded body. As can be understood from FIG. 12, when the particle size is as small as 45 μm or less, the density of the soft magnetic molded body sharply decreases, which is not preferable in terms of ensuring strength. However, even when the particle size was 45 μm or less, the decrease in the magnetic flux density of the soft magnetic molded body was small.

Further, the relationship between the powder particle size of the iron powder particles and the specific resistance of the soft magnetic compact was measured, and similarly, the relationship between the powder particle size and the bending strength of the soft magnetic compact was measured. Figure 1 shows the measurement results
2 shows. In this case, since it was a preliminary test, iron powder particles not subjected to ferrite plating were used. In FIG. 12, the mark ◯ indicates the specific resistance (ρ: μΩcm). Δ indicates bending strength (Rtr: kgf / mm ² ). As can be seen from FIG. 12, when the particle size of the iron powder particles was large, the specific resistance tended to be small. Regarding the bending strength, the change in the particle size of the iron powder particles did not significantly affect the bending strength.

(Application example) FIG. 13 shows a switched reluctance motor (SRM: Switched Rel) mounted on a vehicle or the like.
uctance Motor). The switched reluctance motor includes a stator core 600 and a rotor core 7 rotatably arranged in the stator core 600.
00 and. The stator core 600 includes a first ring body 610 having a large diameter and a plurality of inward projections 620 protruding inward in the radial direction of the first ring body 610. The rotor core 700 includes a second ring body 710 having a shaft hole 711 and having a diameter smaller than that of the first ring body 610, and a plurality of outward projections 720 protruding radially outward of the second ring body 710. Have. A rotary shaft 712 is fitted in the shaft hole 711. Each inward projection 62 of the stator core 600
0 is equipped with a winding coil 650 for obtaining a rotating magnetic field. Since the rotor core 700 is not equipped with a winding coil, the structure can be simplified. One or both of the rotor core 700 and the stator core 600 can be formed of the soft magnetic molded body according to the present invention.

Specifically, the second ring body 710 and the outward projection 720 of the rotor core 700 can be formed of the soft magnetic molded body according to the present invention. In addition, the stator core 60
The first ring body 610 of 0 and the inward projection 620 can be formed by the soft magnetic molded body according to the present invention.

In this way, since it is possible to increase the specific resistance while increasing the magnetic permeability, it is possible to suppress the eddy current even when the frequency of the alternating magnetic field is high, and consequently the loss caused by the eddy current. Can be reduced. Since the switched reluctance motor has a high torque / inertia ratio, it is reversible and can be driven at a high speed and with a large torque at a variable speed.

FIG. 14 shows an example of a rotor used in the above-mentioned switched reluctance motor. According to the example shown in FIG. 14, the rotor core 700B has a second ring body 710B having a shaft hole 711B and a plurality of outward protrusions 720B protruding radially outward of the second ring body 710B. The rotor core 700B is formed of the soft magnetic molded body according to the present invention. Shaft hole 711B of rotor core 700B
A rotary shaft 712B (material: SCM20) is fitted on the shaft.

FIG. 15 shows a plunger type solenoid device 800 which is an example of an electromagnetic actuator. The solenoid device 800 includes a bottomed cylindrical soft magnetic core 810 having a chamber 811, an exciting coil 820 held in the chamber 811 of the soft magnetic core 810, and a movable plunger 830 as an operator inserted in the chamber 811. And the movable plunger 83
It has a return spring 840 connected to 0. Excitation coil 82
The plunger 830 moves in accordance with the energization of 0. When the exciting coil 820 is not energized, the spring force of the return spring 840 causes the plunger 830 to return to its original position.

(Others) The soft magnetic molded body according to the present invention is the above-mentioned switched reluctance motor (SRM).
The present invention can be applied not only to the stator core and rotor core of DC motors, induction motors, and synchronous motors, but also to the soft magnetic cores of solenoid valves as electromagnetic actuators, not limited to the solenoid device 800. be able to. The material and particle size of the iron powder particles are not limited to those used in the first embodiment, and can be changed as appropriate. In the first embodiment, the ferrite plating treatment is carried out by the apparatus shown in FIG. 7, but it is not limited to this apparatus. The present invention is not limited to the embodiments and application examples described above and shown in the drawings, but can be implemented with appropriate modifications without departing from the scope of the invention.

[0056]

The soft magnetic particles for motors or electromagnetic actuators and the method for producing the same according to the present invention are advantageous in increasing the magnetic permeability and the specific resistance.

The soft magnetic molded body for a motor or electromagnetic actuator and the method for producing the same according to the present invention are advantageous in increasing the magnetic permeability and the specific resistance. According to the soft magnetic molded body for the motor or the electromagnetic actuator according to the present invention, the degree of freedom in shape can be increased as compared with the case where a number of silicon steel plates are laminated in the thickness direction to form the soft magnetic molded body. Is advantageous to.

[Brief description of drawings]

FIG. 1 is an electron micrograph (magnification: 1000 times) of iron powder particles used in the first example.

FIG. 2 is an electron micrograph (magnification: 5000 times) of iron powder particles used in the first example.

FIG. 3 is an electron micrograph (magnification: 50) showing a state where the surface of the iron powder particles used in the first example is coated with a ferrite layer.
0 times).

FIG. 4 is an electron micrograph (magnification: 50) showing a state in which the surface of the iron powder particles used in the first example is coated with a ferrite layer.
0 times).

FIG. 5 is an electron micrograph showing a state in which a ferrite layer is coated on the surface of iron powder particles that have not been subjected to an acid contact step (magnification:
500 times).

FIG. 6 is an optical micrograph of a soft magnetic compact formed by pressure-molding an aggregate of soft magnetic particles in which a surface of iron powder particles used in the first example is coated with a ferrite layer.

FIG. 7 is a schematic view of an apparatus for performing a ferrite plating process on iron powder particles.

FIG. 8A is a conceptual diagram schematically showing soft magnetic particles in which the surface of the iron powder particles used in the first embodiment is coated with a ferrite layer, and FIG. 8B is the number of crystal grains / reduction. It is a conceptual diagram which shows typically the soft magnetic particle of the state which covered the ferrite layer on the surface of the iron powder particle which has not passed through the process.

FIG. 9 is a graph showing the relationship between the specific resistance of the soft magnetic molded body and the initial magnetic permeability.

FIG. 10 is a graph showing the results of preliminary tests and showing the relationship between the particle size of iron powder particles and magnetic permeability.

FIG. 11 is a graph showing the results of preliminary tests and showing the relationship between the particle size of iron powder particles and the density of soft magnetic compacts.

FIG. 12 is a graph showing the results of preliminary tests and is a graph showing the relationship between the particle size of iron powder particles, the specific resistance of soft magnetic moldings, and the bending strength.

FIG. 13 is a configuration diagram showing an application example and schematically showing a switched reluctance motor (SRM).

FIG. 14 is a configuration diagram showing an application example and schematically showing a rotor core of a switched reluctance motor (SRM).

FIG. 15 is a configuration diagram showing a plunger type solenoid device which is an example of an electromagnetic actuator.

[Explanation of symbols]

In the figure, 600 is a stator core, 650 is a winding coil, 70
0 indicates a rotor core.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Wataru Yagi             Aichi, 2-chome, Asahi-cho, Kariya city, Aichi prefecture             Within Seiki Co., Ltd. (72) Inventor Yoshiharu Isuda             Aichi, 2-chome, Asahi-cho, Kariya city, Aichi prefecture             Within Seiki Co., Ltd. (72) Inventor Ichiro Arita             Aichi, 2-chome, Asahi-cho, Kariya city, Aichi prefecture             Within Seiki Co., Ltd. (72) Inventor Toshiya Kojima             Aichi, 2-chome, Asahi-cho, Kariya city, Aichi prefecture             Within Seiki Co., Ltd. (72) Inventor Makoto Okabayashi             Aichi, 2-chome, Asahi-cho, Kariya city, Aichi prefecture             Within Seiki Co., Ltd. (72) Inventor Naoki Kamiya             5-50 Hachikencho, Kariya City, Aichi Stock Association             Company Imula Materials Development Laboratory (72) Inventor Masaki Abe             5-8-502 Kitamine, Ota-ku, Tokyo F-term (reference) 4K018 BA14 BC22                 5E041 AA01 AA02 AA03 AA04 AA05                       AA07 BC01 CA04 CA10 HB05                       HB14 HB17 NN01 NN05 NN06    (54) [Title of Invention] Production of soft magnetic particles for motors or electromagnetic actuators, soft magnetic particles for motors or electromagnetic actuators                     Manufacturing method, soft magnetic molded body for motor or electromagnetic actuator, soft magnet for motor or electromagnetic actuator                     For producing flexible molded body

Claims (10)

[Claims] 1. A soft magnetic particle for a motor or an electromagnetic actuator, wherein the surface of iron powder particles containing iron as a main component is coated with a soft ferrite layer by ferrite plating. 2. The soft ferrite layer according to claim 1, wherein the soft ferrite layer has a spinel structure and has a composition formula of (Fe, M) ₃ O ₄ , and M is iron (Fe), cobalt (Co), nickel ( Ni), manganese (Mn), zinc (Zn), chromium (Cr), aluminum (Al), and titanium (Ti), at least one kind of soft magnetic particles for a motor or an electromagnetic actuator characterized by the above-mentioned. 3. The soft magnetic particle for a motor or an electromagnetic actuator according to claim 1, wherein the soft ferrite layer has a thickness of 0.01 μm to 10 μm. 4. The iron powder particles according to claim 1, wherein the iron powder particles are pure iron (Fe), iron-aluminum system (Fe).
-Al system), iron-silicon system (Fe-Si system), iron-nickel system (Fe-Ni system), iron-silicon-aluminum (Fe-Si-Al system), iron-chromium system (Fe-Cr).
System), at least 1 of iron-cobalt system (Fe-Co system)
A soft magnetic particle for a motor or an electromagnetic actuator characterized by being a seed. 5. A method for producing soft magnetic particles for use in a motor or an electromagnetic actuator, comprising the steps of preparing iron powder particles containing iron as a main component, and the iron powder particles having soft ferrite on the surface by ferrite plating. A coating step of coating a layer, the method for producing soft magnetic particles for a motor or an electromagnetic actuator. 6. The method according to claim 5, wherein, prior to the coating step, the soft magnetic particles are heated to a high temperature in a heating atmosphere to reduce the number of crystal grains in one iron powder particle as compared with before heating. A method for producing soft magnetic particles for a motor or an electromagnetic actuator, which comprises performing a step of reducing the number of crystal grains. 7. A softener for a motor or an electromagnetic actuator according to claim 5, wherein an acid contacting step of bringing the iron powder particles into contact with an acid is carried out prior to the coating step. Method for producing magnetic particles. 8. A soft magnetic compact for a motor or an electromagnetic actuator, characterized in that particles of a powder aggregate containing the soft magnetic particles according to any one of claims 1 to 7 as main elements are bonded to each other. . 9. The stator core of the motor according to claim 8,
A soft magnetic molded body for a motor or an electromagnetic actuator, which is used for at least one of a rotor core of a motor and a soft magnetic core of an electromagnetic actuator. 10. A step of preparing a powder aggregate having the soft magnetic particles according to any one of claims 1 to 7 as a main element, and softening by soft-pressing the powder aggregates and bonding them to each other. A method for manufacturing a soft magnetic molded body for a motor or an electromagnetic actuator, which comprises performing a coupling step for obtaining a magnetic molded body.