JPS59177902A - Core - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a core suitable for high frequency applications, and more specifically, it relates to a core suitable for high frequency applications, and more specifically, to a core suitable for high frequency applications, which has low iron loss in the high frequency range and constant magnetic permeability as a magnetic core for transformers, chiller coils, etc. The present invention relates to a powdered amorphous alloy core for use.

(Technical Background of the Invention and Problems Therewith) Conventionally, crystalline materials such as permalloy and ferrite have been used in magnetic cores for transformers used at high frequencies such as switching regulators.

However, since permalloy has a low resistivity, it has a problem in that iron loss at high frequencies increases. or,
Ferrite has a small loss at high frequencies, but its magnetic flux density is also small, at most 5000G. Therefore, when used at high operating magnetic flux density, it approaches saturation, resulting in an increase in iron loss. ing. Recently, there has been a desire to reduce the size of transformers used at high frequencies, such as power transformers used in switching regulators, but in this case, it is necessary to increase the operating magnetic flux density, so ferrite iron is used. Increased losses pose a major problem in practice.

On the other hand, silicon steel is used as the magnetic core for the choke, but it is unsuitable for high frequencies because it generates a lot of heat at high frequencies.

On the other hand, amorphous magnetic alloys that do not have a crystalline structure have recently attracted attention because they exhibit excellent soft magnetic properties such as high magnetic permeability and low coercive force. These amorphous magnetic alloys are made of iron (Fe
), cobalt (CO), nickel (Ni), etc., and phosphorus (P) as an amorphous element (metalloid).
), carbon (C), boron (B), silicon (8'), aluminum (A/), germanium (Ge), etc.

Amorphous alloys are attracting attention as magnetic cores for high frequencies such as transformers and choke coils because they have low core loss and high saturation magnetic flux density, especially at high frequencies. When used in these applications, it is necessary to make a cut core to improve DC superimposition characteristics, but since amorphous alloys have high hardness and springiness, they can be used while maintaining the wound shape. Quite difficult to cut. Further, if the core is impregnated with resin before cutting, the core loss may increase by 4 to 6 times, and in this case, the excellent properties of the amorphous alloy cannot be effectively utilized.

(Object of the Invention) The present invention has been made in view of the above drawbacks, and provides a core for high frequencies such as transformers and chokes without impairing the low core loss at high frequencies of an amorphous alloy. It is something.

(Summary of the Invention) As a result of intensive research to solve the problems related to the cut core of the amorphous alloy described above, the inventor has developed a powdered amorphous alloy having a metamorphic layer such as an oxide layer on the surface. It has been found that a core made using this material has good sinterability and low iron loss.

That is, the core of the present invention is characterized in that amorphous alloy powder having a metamorphic layer on its surface is bonded via the metamorphic layer. This metamorphic layer contributes to the bonding of the powders, and the core has sufficient strength to withstand use. An oxidized layer is a practical metamorphic layer. In order to obtain an oxidized layer, it is preferable to perform oxidation treatment at a high temperature and under high pressure, for example.

It is desirable that the temperature at this time be as high as possible to trap the formation of crystalline oxides in a short time, but if the temperature is too high, the problem of crystallization of the amorphous alloy will occur, so the temperature should be lower than the crystallization temperature. The temperature is 150-5, specifically 150-5.
The temperature is preferably 00°C, and more preferably 250 to 400"C. As means for increasing the pressure, gas,
Either liquid may be used, but the pressure obtained is 40~
The pressure is preferably 200 atm, more preferably 60 to 100 atm. The treatment time varies depending on the treatment temperature and treatment pressure, but is generally 0.5 to 100 hours, particularly preferably 5 to 24 hours.

A common and easy method is to process in high-temperature steam, such as in an autoclave.

By the above treatment, the oxide film formed and the crystalline oxide contained therein differ depending on the main component of the 4- amorphous alloy, but for example, in an amorphous alloy whose main component is Fe. In some cases, a layer whose main composition is Fe3O4 is formed.

The amorphous alloy to be applied to the present invention can be expressed, for example, by the following formula (11 or more selected from rare earth elements, X is B or B).
and 81 (However, Si is 10 atomic % or less in the formula.

), a and b are each 0.02≦a≦0.0
It represents a number that satisfies the relationships: 75 and 15≦b<30.

) There is something indicated by

In the amorphous alloy represented by the above formula (1) of the present invention,
The preferred composition ratio of each element is as follows.

The above formula CI) amorphous alloy is mainly composed of iron (Fe),
This is mixed with various additive elements.

In the amorphous alloy represented by the above formula, M is a component that contributes to reducing core loss and increasing crystallization temperature in the high frequency region, and its composition ratio a to Fe is 0.
The range of 02≦a≦0.075 is preferable.

When a is 0.02 or more, the above effects can be sufficiently obtained, and on the other hand,
Up to 0.075, the Curie temperature does not drop and is very practical. This increase in crystallization temperature reduces the sintering temperature, resulting in a core with higher strength.

In the amorphous alloy represented by formula (I)-7', both X are elements for making the alloy of the present invention amorphous, and boron (
I3) or boron ([3) and silicon (8i). The blending amount of X is preferably a value satisfying 15≦b≦30 in terms of atomic concentration. When b is 15 or more, the Curie temperature decreases little, and the crystallization temperature also does not decrease.

On the other hand, if it exceeds 30, it is difficult to obtain an amorphous state. In addition, B
and Sl, the amount of Sl is 10
It is preferable to make it less than atomic %. When 8ii is within 10 atomic %, an increase in core loss of the resulting amorphous alloy can be prevented.

The amorphous alloy powder used in the present invention can be obtained by the spark erosion method, the atomization method, or by pulverizing an amorphous alloy ribbon.

In the present invention, the amorphous alloy subjected to the oxidation treatment is compression molded and heat treated in the air at 400 to 500°C for 2 to 6 hours to obtain sufficient strength while maintaining insulation through the oxide film. It is possible to obtain a core having . In addition,
This heat treatment serves both for sintering and for obtaining low iron loss.

The high-frequency core of the present invention is not bonded with a binder such as resin or glass, so the high saturation magnetic flux density of the amorphous alloy is maintained, and it not only reduces iron loss but also reduces size. is also possible.

(Examples of the Invention) Example 1 A powdered amorphous alloy having the composition shown in Table 1 was exploded by an atomization method. These powders were heated in an autoclave for 30 min.
Oxidation treatment was performed at 0°C for 8 hours, and after confirming the formation of an oxide film, it was compression molded into a ring-shaped core with an outer diameter of 18μ, an inner diameter of 12μ, and a height of 10μ. The cores of each composition were then heated at 450°C for 5
Heat treatment was performed in the absence of a magnetic field for a period of time, the primary coil and the secondary coil were wound -'/ (the number of turns was 50 in each case), and the iron loss was measured using a U-function meter. The measurement conditions are an operating magnetic flux density of 3KG.
and 10KH2, 20KH2, 50KHz and 10
It was conducted at each frequency of 0 KHz. The saturation magnetic flux density was determined from a DC BH curve.

Table 1 shows the results.

Comparative example 1゜Mn, Z, which has been conventionally used for switching power supplies
1ζ using n-ferrite as a comparative product.

Iron loss and saturation magnetic flux density were measured for the three types of ring-shaped samples described above in the same manner as in Example 1.

These results are listed in Table 1 together with Examples.

1 Table 8 - As is clear from the table, it was confirmed that the core using the powdered amorphous alloy of the present invention has a higher magnetic flux density and lower iron loss than the conventional ferrite product. .

(Effects of the Invention) The core of the present invention can be formed as a core without impairing the characteristic of the amorphous alloy of low iron loss at high frequencies, and is suitable for high frequency cores such as transformers and chokes.

Note that conventional materials such as ferrite can also be mixed within a range that does not impair the characteristics of the amorphous alloy powder.

Claims (4)

[Claims] (1) A core formed by bonding amorphous alloy powder having a metamorphic layer on its surface via a metamorphic layer. (2) The core according to claim 1, wherein the metamorphosed layer is an oxidized layer. (3) The core according to claim 2, wherein the oxidized layer is formed by heat treatment under pressure. (4) The core according to claim 1, wherein the amorphous alloy powder has a composition represented by the following formula. Any one or more of Y: 8i, B Any one or more of 0.02≦a≦
0.075 15≦b≦30