JPH0582373A - Manufacture of magnetic core - Google Patents

Abstract

PURPOSE:To provide a choke coil wherein the width of a heat treatment temperature is widened, an iron loss is small and a stable characteristic is provided in a low-permeability region. CONSTITUTION:An iron-based amorphous ribbon is wound. Thereby, a magnetic- core main body is obtained. After that, the magnetic-core main body is heat- treated in a so-called wet atmosphere whose unit steam amount in terms of 25 deg.C is 5 to 500m/m<3>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to smoothing of overlapping ripples on direct current, cores and active filters of noise filters for normal mode, and magnetic cores having excellent constant permeability used for high frequency transformers. It relates to a manufacturing method.

[0002]

2. Description of the Related Art A choke coil used in a noise filter of this kind or a high frequency transformer is required to have a constant magnetic permeability, that is, a magnetic permeability having a substantially constant property without being strongly dependent on the magnitude of a magnetic field H. To be done.

In order to satisfy this constant permeability, in a so-called amorphous core made of an amorphous alloy, first, a thin strip of an iron-based amorphous alloy (hereinafter referred to as an amorphous ribbon) is wound a predetermined number of times. It was taken, heat-treated, impregnated with an adhesive such as an epoxy resin, solidified, and then provided with a gap for cutting a part of the magnetic path to realize the above-mentioned constant permeability.

On the other hand, this type of choke coil is expected to be used in the high frequency region of several hundreds of kHz or more in the future, but in such a high frequency region, the heat generated from the core, that is, the iron loss. Had to be suppressed to a minimum.

With respect to this point, in the magnetic core having the gap as described above, in addition to the contraction stress at the time of impregnation curing of the epoxy resin and the processing strain at the time of cutting, the iron loss greatly increases due to the insulation failure of the cut surface and the like. There was a problem to do.

In view of the above points, various techniques have been proposed for realizing constant magnetic permeability without forming the gap.

The earliest is "Pro", published in 1981.
c, 4th Int. Conf. on Rapidl
y Metals] (p. 1007 to p. 1010), a study conducted by “A. Datata” et al. showed that α-Fe microcrystals were deposited in the vicinity of the surface of the amorphous ribbon after heat treatment, which resulted in constant magnetic permeability. Have been revealed to be expressed.

After that, Japanese Patent Laid-Open No. 6324016/1988 proposes heat treatment at a temperature lower than the microcrystallization temperature for 10 hours or more to stably suppress crystal precipitation on the surface and realize constant permeability. Has been done.

On the other hand, the bonding of the Fe-based amorphous ribbon surface
Regarding crystallization, J. Japan Inst. Metal
s, Vol. 52, No. 4 (1988) pp420-
427, N. Morita et al.
Is included, the amorphous ribbon (Fe-B-S
(i type) crystallization occurs in the vicinity of the surface layer, and at the same time, iron loss is poor.
It has been reported that a phenomenon has been found. According to this report
If so, Fe_78.5B₁₃Si _8.5Amorphous alloy ribbon 673K
Ar, N when annealed at₂, Dry H₂And N₂+ O₂
The iron loss was improved by annealing in the air, and the iron loss values were almost the same.
However, the amorphous ribbon is not subject to dew point 323K (5
0 ° C) wet H₂Iron loss was poor in annealing in the atmosphere.
It is written that it will become. However, in this document
The heat treatment method for obtaining the property is not described at all.
Yes.

[0010]

However, in the above-mentioned prior art, since fine crystals are deposited on the surface of the amorphous ribbon to obtain the core having the desired constant magnetic permeability, a fine temperature change is caused during the heat treatment. However, there was a problem in that it resulted in fluctuations in magnetic permeability, and it was not possible to supply stable products in large quantities.

The present invention has been made in view of the above problems, and by controlling the heat treatment conditions, particularly the amount of water vapor in the heat treatment atmosphere, a core (magnetic core) having a constant magnetic permeability even when a gap is not formed is formed. It is an object of the present invention to provide a core (magnetic core) having a stable property in a low magnetic permeability region with a small iron loss, by widening a suitable range of heat treatment temperature for providing constant magnetic permeability.

[0012]

The present inventor has introduced a specific amount of humidity into the atmosphere during heat treatment to achieve a wide temperature range even when a gap is not provided in the magnetic core, and to reduce iron loss and to reduce permeability. It was found that stable constant permeability can be obtained in the magnetic region.

That is, according to the present invention, after a magnetic core main body made of an iron-based amorphous alloy is obtained, the magnetic core main body is soaked at a unit steam amount of 5 to 500 g / m ³ at 25 ° C. Heat treatment is performed in an atmosphere.

The magnetic core body in the present invention is obtained by winding or laminating an iron-based amorphous ribbon. For example, a ribbon (thin band) made of amorphous alloy is processed into a slit shape and wound, and then the winding end is fixed by attaching a Kapton tape or the like, or an amorphous ribbon is laminated, and if necessary, a predetermined shape is formed. Can be punched out.

The amorphous metal used in the present invention is an Fe-based amorphous alloy (metal) having a Fe content of 50 atomic% or more. These Fe-based amorphous alloys include Fe-B and Fe. -BC, Fe-
B-Si, Fe-B-Si-C, Fe-B-Si-C
Examples include Fe-based materials such as r, Fe-Co-B-Si, and Fe-Ni-Mo-B.

Among these, Fe _X Si _Y B _Z M _W can be exemplified as a particularly preferable Fe-based amorphous metal. Here, X = 50 to 85, Y = 5 to 15, Z = 5 to 25 (X,
Both Y and Z represent atomic%). Also, M
Is Co, Ni, Nb, Ta, Mo, W, Zr, Cu, C
Examples of the metal include one or a combination of two or more of r, Mn, Al, P and the like, and _W = 0 to 10 (preferably 0 to 5) atomic%.

As the wet atmosphere, the unit water vapor amount in a gas atmosphere at 25 ° C. is 5 to 500 g / m ³
What is used.

The unit amount of steam (content) in the wet atmosphere is 5
~ 500g / m ^{3 by} the range, even if the gap is not provided in a wide heat treatment temperature range, less iron loss,
Moreover, stable constant magnetic permeability can be obtained in the low magnetic permeability region.

[0019] The unit amount of water vapor in the present invention (25 ° C. conversion) is preferably 8~200g / m ^3, more preferably 10 to 80 g / m ^3, and most preferably 20 to 80 g / m ³
Is. In the present invention, the unit water vapor amount in the gas atmosphere at 25 ° C. is the unit water vapor amount converted when the unit water vapor amount in the gas atmosphere at a predetermined (heat treatment) temperature is 25 ° C. under atmospheric pressure.

The heat treatment atmosphere may be the same as the atmosphere, but it is preferable to use an inert gas atmosphere such as nitrogen, argon or helium atmosphere.
It is preferable to carry out in an inert gas atmosphere because it is possible to prevent peeling off of the Kapton tape used for stopping the ends of the amorphous ribbon, and since a film with good weather resistance is formed on the surface, especially from the practical point of view. A nitrogen atmosphere is preferable.

[0021]

FIG. 5 shows changes in magnetic permeability with an increase in the DC superimposed magnetic field for each heat treatment temperature.

The desired constant magnetic permeability is, for example, as represented by a dust-based smooth choke, it is desirable that the sudden decrease in the magnetic permeability due to an increase in the DC superimposed magnetic field is small.

As shown in FIG.
Only by measuring the magnetic permeability in e), it is possible to infer the magnetic permeability when a DC magnetic field is superposed, that is, the constant magnetic permeability.

Therefore, it is inevitable that constant magnetic permeability can be obtained by lowering the magnetic permeability of the magnetic core in the state where no magnetic field is applied (0 Oe).

By the way, in general, the heat treatment temperature may be raised to lower the magnetic permeability, but the iron loss is increased by raising the heat treatment temperature. In this respect, the present invention realizes the control of the magnetic permeability in a wide range at a relatively low temperature as described below.

FIG. 1 shows a magnetic core body obtained by winding an amorphous metal ribbon (the same as the core body before heat treatment manufactured in the example was used) (without a gap).
On the other hand, as a heat treatment atmosphere, in a dry state and a wet state (25 ° C.) in each of air, oxygen and nitrogen atmospheres.
The relationship between the heat treatment temperature and the magnetic permeability when the unit steam amount in conversion is 23 g / m ³ ) is shown.

The term "permeability" as used herein means Precision LCR meter (HP42) manufactured by Hewlett Packard Co., Ltd.
84A) at 100 kHz and when an AC magnetic field of 5 mOe was applied (DC magnetic field was 0 (Oe)).
By knowing this magnetic permeability, it is possible to estimate the constant magnetic permeability when a DC magnetic field is superimposed. The range of magnetic permeability that can obtain preferable constant magnetic permeability is 150 to 600.

As is clear from the figure, when the heat treatment is performed in a so-called wet atmosphere, the magnetic permeability can be suppressed in a relatively low temperature range of 450 ° C. (2 hours) or less.

In the present invention, the amount of unit water vapor (content) at 25 ° C. in the magnetic core body is 5 to 500 g / m ³ , preferably 8 to 200 g / m ³ , and more preferably 10 to 80 g / m ³ .
By treating in a moist atmosphere of m ³ , most preferably 20 to 80 g / m ³ , the magnetic permeability of the magnetic core is suppressed even when heat-treated in a relatively low temperature region, and iron loss is small in a wide temperature range, In addition, stable constant permeability can be obtained.

The relationship between the heat treatment temperature and the iron loss under each atmosphere condition when the same magnetic core body as the one before the heat treatment manufactured in the example is used is shown in FIGS. 2 and 7, the magnetic permeability and the iron loss. FIG. 3 shows the relationship with.

The moist air in FIGS. 2, 3 and 7
Oxygen and nitrogen also have a unit water vapor content of 2 at 25 ° C.
Indicates air, oxygen or nitrogen in a state of ³ g / m ³ .

In FIGS. 2 and 7, the change in iron loss with respect to the heat treatment temperature is almost the same in the dry atmosphere and the wet atmosphere, and the heat loss in the wet atmosphere causes less iron loss than the heat treatment in the dry atmosphere. It shows that it does not increase.

According to FIG. 3, it can be seen from the range where the magnetic permeability exceeds 600 that the wet atmosphere has the property of increasing the iron loss as compared with the dry atmosphere, but the constant magnetic permeability aimed at by the present invention can be obtained. In the so-called low magnetic permeability region in the magnetic permeability range of about 100 to 600, there is no deterioration of iron loss as compared with the dry atmosphere.

In the present invention, in order to suppress the magnetic permeability of the magnetic core on the low temperature side, obtain a constant magnetic permeability in a wide temperature range, and prevent the iron loss from deteriorating, the heat treatment temperature T is expressed by the following equation 1, particularly the equation 2
It is preferably in the range of.

[0035]

[Formula 1] Tx−5 ° C. ≧ T ≧ Tx−100 ° C.

[0036]

## EQU00002 ## Tx-20.degree. C..gtoreq.T.gtoreq.Tx-65.degree. C. However, in the formulas 1 and 2, Tx represents the crystallization temperature of the amorphous alloy.

As shown in the equations 1 and 2, the heat treatment temperature T is limited by the crystallization temperature Tx, because the permeability is impaired at a temperature lower than this (Tx-100 ° C.). This is because iron loss increases at temperatures higher than the high temperature side (Tx-5 ° C).

In the present invention, in order to obtain good constant permeability and iron loss resistance, it is particularly preferable to carry out in the range of the numerical formula 2.

The crystallization temperature Tx in this case is the amount of the sample 1
0 mg, heating rate 10 ° C / min, extension line from the exothermic peak curve measured in N ₂ atmosphere to the high temperature side of the low temperature side baseline of the lowest temperature exothermic peak and the slope to the low temperature side curve of the exothermic peak Was calculated as the intersection with the tangent line drawn at the maximum point.

The heat treatment time is not particularly limited,
1 minute to 20 hours, especially 30 minutes to 3 hours are preferable. The optimum heat treatment temperature range depends on the alloy composition,
Allied's amorphous alloy 2605S-2
When (Fe ₇₈ B ₁₃ Si ₉ (atomic%): Tx = 501 ° C.) is used, the optimum heat treatment temperature range is 496 ° C. to 401 ° C.
Particularly preferably, it is 481 ° C to 436 ° C.

FIG. 4 shows the relationship between magnetic permeability and unit water vapor content. As is clear from the figure, the magnetic permeability can be suppressed with a small amount of water vapor as the treatment temperature becomes lower. That is, it was found that stable constant magnetic permeability can be obtained by introducing a wet atmosphere in such a low temperature region.

[0042]

EXAMPLES Examples of the present invention will be described below.

Amorphous ribbon manufactured by Allied Company (product name: Metglas, product number: 2605S-2, composition: F
e ₇₈ B ₁₃ Si ₉ (atomic%), thickness 21 μm, width 10 mm)
The obtained toroidal magnetic core body having an outer diameter of 25 mm and an inner diameter of 15 mm is wound in an electric furnace at a treatment temperature of 445
Annealed for 2 hours at ℃. At this time, as the annealing atmosphere, the unit vapor amount in nitrogen gas at 25 ° C. is 25 g /
A wet atmosphere of m ³ was used. Then, the magnetic core body is housed in a case made of synthetic resin without providing a gap,
It was a magnetic core.

FIG. 6 shows the relationship between the magnetic permeability and the DC superimposed magnetic field of this magnetic core. In the same figure, for comparison, the respective characteristics of a gap choke obtained under the same conditions as those of the magnetic core and a dust choke obtained by molding sendust compacts are plotted.

As is clear from the figure, the magnetic core obtained in this example has characteristics similar to those of the dust choke, and it is possible to obtain higher magnetic permeability than the dust choke over the entire superposition. .. Further, unlike the gap choke, there was no sudden decrease in magnetic permeability below 100 (Oe).

[0046]

According to the present invention, by controlling the amount of water vapor in the heat treatment atmosphere, it is possible to provide a magnetic core having a small iron loss and stable characteristics in the low magnetic permeability region.

Further, since the range of temperature control can be widened by the heat treatment in the wet atmosphere, a product having stable characteristics can be supplied even if there is some error in the control temperature, thus improving the productivity of the magnetic core. be able to.

A preferable application of the magnetic core obtained by the method of the present invention is a choke coil.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between heat treatment temperature and magnetic permeability in each heat treatment atmosphere in the present invention.

FIG. 2 is a graph showing the relationship between heat treatment temperature and iron loss in each processing atmosphere in the present invention.

FIG. 3 is a graph showing the relationship between magnetic permeability and iron loss in the present invention.

FIG. 4 is a graph showing the relationship between magnetic permeability and the amount of water vapor in the present invention.

FIG. 5 is a graph showing the relationship between the magnetic permeability and the DC superimposed magnetic field in the present invention.

FIG. 6 is a graph showing a DC superimposed magnetic field characteristic in comparison with a gap choke and a dust choke.

FIG. 7 is a graph showing the relationship between heat treatment temperature and iron loss in each processing atmosphere in the present invention.

Claims (4)

[Claims] 1. A magnetic core body made of an iron-based amorphous alloy,
A method for producing a magnetic core, comprising performing heat treatment in a humid atmosphere having a unit water vapor amount of 5 to 500 g / m ³ at 25 ° C. conversion. 2. The magnetic core body is obtained by winding or laminating a ribbon of an iron-based amorphous alloy.
A method for manufacturing the magnetic core described. 3. The method of manufacturing a magnetic core according to claim 1, wherein the moist atmosphere is formed in a nitrogen atmosphere. 4. The heat treatment temperature is in the range of Tx−5 ° C. to Tx−100 ° C. at the crystallization temperature Tx, and 1 minute to 20 minutes.
The method for manufacturing a magnetic core according to claim 1, wherein the heat treatment is performed for a time.