JPH079057B2 - Amorphous alloy magnetic core manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing an amorphous alloy magnetic core.

[Technical background of the invention and its problems]

Conventionally used as a magnetic core of an electromagnetic device,
There are crystalline materials such as permalloy and ferrite. However, since permalloy has a small specific resistance, iron loss in the high frequency region becomes large. Further, although ferrite has a small iron loss in the high frequency region, it has a drawback that the saturation magnetic flux density is as small as about 5000G.

On the other hand, an amorphous alloy containing P, C, B, Si, Al, Ge, etc. based on Fe, Co, Ni, etc. and having no crystallinity has excellent soft magnetic properties, The research is active.

In the production of amorphous alloys, it is common to perform heat treatment to improve magnetic properties and to improve magnetic properties such as reduction of iron loss. Such heat treatment is carried out in a range of the Curie temperature or higher and the crystallization temperature or lower as the atmospheric conditions, usually under reduced pressure (in vacuum) in nitrogen, which improves magnetic properties to some extent, such as reduction of iron loss. To be done. Further, it has been reported that the iron loss in the heat treatment in the air is inferior to the above conditions.

[Object of the Invention]

An object of the present invention is to provide a method for manufacturing an amorphous alloy magnetic core, which can further reduce the iron loss of the amorphous alloy magnetic core.

[Outline of Invention]

The present invention, after winding or laminating an iron-based amorphous alloy ribbon having a positive saturation magnetostriction, forms an oxide film layer having a thickness of 200 Å or more and 3000 Å or less on the entire surface of the alloy ribbon during strain relief heat treatment. This is a method for producing an amorphous alloy magnetic core.

Here, various magnetic alloys are used as the amorphous alloy, and (Fe _1- aMa) _100- bXb M: Ti, V, Cr, Mn, Co, Ni, Zr, Nb, Mo, Hf, Ta , At least one of W: at least one of Si, B, P, C, Ge 0 ≦ a ≦ 0.15 12 ≦ b ≦ 30, Fe-based amorphous alloy having a positive saturated magnetostriction is preferable. .

The addition of M has the effect of reducing iron loss and increasing the crystallization temperature in the high frequency region. The effect appears even if added in a small amount, but in practice, it is preferable that a ≧ 0.01.
If a> 0.15, Tc becomes too low, which is not preferable in practice.

Further, X is an element essential for amorphization, and in consideration of thermal stability in practical use, a combination of Si and B is preferable. B <12
And b> 28, it becomes difficult to amorphize, so 12 ≦ b
≦ 28 is preferable, and 15 ≦ b ≦ 25 is more preferable. Si is 2
-13%, preferably 2-8% is good.

As a method for forming an oxide film during the heat treatment, it is preferable to mix it with an inert gas such as nitrogen and oxygen in a gas, and further forcibly supply the gas between the layers of the wound or laminated magnetic core. As a result, a further lower iron loss can be realized.

When the ratio of the inert gas to oxygen, which is an atmospheric condition, is (100-C): C in molar ratio, 0.01≤C≤10 is preferable. C <
A core loss of 0.01 does not result in a marked reduction, and a C> 10 deteriorates the characteristics. Preferably 0.01 ≦ C ≦ 5
Is.

Further, it is preferable to forcibly supply the atmosphere between the layers of the magnetic core during the heat treatment. This is because an oxide film is formed on the entire surface of the ribbon of the amorphous alloy forming the magnetic core, and under normal conditions with almost no convection, a uniform oxide film is formed only on the outer periphery of the magnetic core. This is because the surface of the inner ribbon is only slightly seen at both ends of the ribbon, and it is difficult to obtain low iron loss. Examples of the atmosphere supply method include a method of blowing the atmosphere from a nozzle-shaped outlet, a method of absorbing the atmosphere by reducing the pressure of the core, and the like.

Regarding the thickness of the oxide film of the amorphous alloy, when the thickness of the oxide film is less than 200Å, the effect of reducing iron loss is small, and when it exceeds 3000Å, the iron loss increases rather. A significant effect in reducing iron loss is obtained when an oxide film having a thickness in the range of 200 Å or more and 3000 Å or less is formed.

The reason for this is that if an oxide film layer with a thickness of 200 Å or more and 3000 Å or less is formed on the surface of the amorphous alloy ribbon during heat treatment, compressive stress is applied in the in-plane direction of the ribbon when the temperature is lowered to room temperature. Occurs, and the interaction between it and the positive magnetostriction of the iron-based amorphous alloy causes induced magnetic anisotropy in the thickness direction of the ribbon, which hinders the movement of the magnetic domain wall. This is considered to reduce the eddy current loss that occupies It is preferably 200 to 2000Å.

Example of Invention

 The present invention will be described below based on examples.

Example 1 A (Fe _0.95 Nb _0.05 ) ₈₃ Si ₅ B ₁₂ amorphous alloy ribbon having a width of 10 mm and an average thickness of 20 μm produced by a single roll method is wound, and a toroidal shape having an outer diameter of 18 mm and an inner diameter of 12 mm is wound. Got a magnetic core. The magnetic core
Heat treatment was performed for 30 minutes at 460 ° C. in an atmosphere of nitrogen: oxygen = 99: 1 while forcibly blowing the gas onto the magnetic core, and the high frequency iron loss was measured using a U function meter. For comparison, the same heat treatment was performed in nitrogen and air. FIG. 1 shows the iron loss characteristics under the condition of f = 50 KHz. Here, the examples are represented by solid lines, the heat treatment in nitrogen of the comparative examples is represented by a broken line, and the heat treatment in the atmosphere is represented by a chain line.

In the same figure, the thickness of the oxide film layer formed on the surface of the amorphous alloy ribbon is additionally shown. The thickness of the oxide film layer is a value obtained by the Auger analysis method.

As is clear from FIG. 1, when heat treatment is performed in a mixed gas of nitrogen and oxygen, an appropriate oxide film layer is formed on the surface of the alloy ribbon, and iron loss is reduced. It is understood that the effect of reducing iron loss is small if the thickness of the oxide film layer is too thin or too thick.

(Example 2) In the same manner as in Example 1, Fe-based amorphous alloys having several kinds of compositions were produced, formed into the same magnetic core shape, and heat-treated in various atmospheres. The heat treatment conditions are the optimum conditions for each alloy. These results are summarized in Table 1, but the iron loss value is f
= 50KHz, Bm = 3KG.

From this table, it can be seen that low iron loss is obtained when the thickness of the oxide film layer formed on the surface of the amorphous alloy during the heat treatment is in the range of 200 Å or more and 3000 Å or less.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY The present invention provides a high frequency magnetic core having a low iron loss, and thus has a great industrial value.

[Brief description of drawings]

FIG. 1 is an iron loss characteristic curve diagram of f = 50 KHz for explaining the effect of the present invention.

Claims (5)

[Claims] 1. An iron-based amorphous alloy ribbon having a positive saturation magnetostriction is wound or laminated, and an oxide film layer having a thickness of 200 Å or more and 3000 Å or less is formed on the entire surface of the alloy ribbon during heat treatment for strain relief. A method for manufacturing an amorphous alloy magnetic core, which is characterized by forming the core. 2. The method for producing an amorphous alloy magnetic core according to claim 1, wherein the heat treatment is performed in a mixed atmosphere of an inert gas and oxygen. 3. The method for producing an amorphous alloy magnetic core according to claim 2, wherein the mixed atmosphere is forcibly supplied during the heat treatment. 4. The mixed atmosphere is 0.01≤C≤10 when the mixed molar ratio of inert gas and oxygen is expressed as (100-C): C.
The method for producing an amorphous alloy magnetic core according to claim 2, characterized in that: 5. The iron-based amorphous alloy has the general formula (Fe _1- aMa) _100- bXb M: Ti, V, Cr, Mn, Co, Ni, Zr, Nb, Mo, Hf, Ta, W. At least one of X: Si, B, P, C, Ge is at least one of 0 ≦ a ≦ 0.15 12 ≦ b ≦ 30. The amorphous alloy magnetic core according to claim 1. Manufacturing method.