JPS61154014A - Dust core - Google Patents

Abstract

PURPOSE:To obtain the dust core which can be subjected to a heat treatment after shaping shaped easily and has the excellent magnetic characteristics by using a bonding agent made of inorganic high molecules. CONSTITUTION:The compression shaped body is used as a magnetic core, which is obtained by compression shaping of magnetic powder through a solvent including inorganic high molecules under the conditions for fabrication of the powder. For the magnetic powder, iron powder, Fe-Al alloy powder, Fe-Si alloy powder, Fe-Ni alloy powder and etc. are available and more preferably, the amorphous alloy powder of small iron loss, particularly that in high frequency zone. this dust core has the excellent shaping property and especially, it can be subjected to a heat treatment so that the high permeability iron loss can be obtained and the magnetic characteristics of the magnetic powder can be sufficiently extracted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a high-frequency magnetic core, particularly a powder magnetic core suitable for alternating current transformers, electric motors, chokes, noise filters, and the like.

[Technical background of the invention and its problems] Fe-8i alloy,
Permalloy, ferrite, etc. have a small resistance, and their magnetocrystalline anisotropy is not zero, so they have the problem of large iron loss in a relatively high frequency range. Since permalloy has a low resistivity, it has the problem of high iron loss at high frequencies. Furthermore, although ferrite has a small loss at high frequencies, its magnetic flux density is also small, at most 5000G, so when used at high operating magnetic flux densities, it approaches saturation, resulting in an increase in iron loss. are doing. In recent years, there has been a desire to reduce the size of transformers that use 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 Increased losses pose a major problem in practice.

It is made by producing powder with magnetic permeability and reducing iron loss at high frequencies, and solidifying it through an insulating layer, and an organic material is used as the insulating layer.

These magnetic cores are mainly used as chokes and noise filters.

However, the powder compact made of the magnetic powder described above has a low magnetic permeability, so in order to obtain a sufficient inductance, the number of windings must be increased, and therefore it is difficult to miniaturize.

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 iron (Fe)
, cobalt (Go>, nickel (Nr>), etc., as well as phosphorus (P), carbon (C), boron (B), silicon (Si) as amorphous elements (metalloids).
), aluminum (Ai'), germanium (Ge)
etc. are contained.

In addition, Fe, Go, Ni, and Ti, Zr, 1-
Amorphous alloys made of alloys such as 1f and Nb are also known.

These amorphous alloys are usually obtained in the form of thin ribbons, and when used as their magnetic cores, the thin ribbons are shaped into toroidal, U-shaped, or
It is used as a wound core formed into an E shape, or as a laminated core made by laminating thin strips into a certain shape. However, these magnetic cores, especially in the U-shape and E-shape, have a drawback in that the manufacturing method thereof is difficult.

In order to eliminate the above-mentioned drawbacks, attempts have been made to produce powder of amorphous magnetic alloy and compact it using, for example, epoxy resin. Usually, an amorphous magnetic alloy is used after its magnetic properties are improved by heat treatment. However, when resin is used as a binder, heat treatment cannot be performed and the characteristics of the amorphous alloy cannot be fully brought out. Also,
When trying to shape amorphous alloy powder after heat treatment,
The disadvantage was that the material was brittle and difficult to mold.

On the other hand, when an inorganic material such as an oxide such as alumina or magnesia is used as an insulating layer, the amorphous alloy is hard and has poor compressibility. The problem was that it was extremely small and impractical.

[Object of the Invention] An object of the present invention is to provide a powder magnetic core manufactured from magnetic powder and having excellent magnetic properties.

[Summary of the Invention] As a result of extensive research in order to solve the above problems, the present inventor has discovered that by using a paint made of an insulating inorganic polymer as a binder for molding magnetic powder, It has been discovered that it is possible to produce a powder magnetic core that can be easily molded and has excellent magnetic properties.

That is, a compression-molded body obtained by compression-molding magnetic powder in the state at the time of powder production through a solvent containing an inorganic polymer is used as a magnetic core.

As magnetic powder, iron powder, Fe-Aj! alloy powder, Fe-3
Examples include i-based alloy powder, Fe-Ni-based alloy powder, etc., but it is preferable to use an amorphous alloy powder that has a small core loss, particularly in a high frequency range.

The amorphous alloy used here generally has the following composition.

That is, when expressed in atomic %, the following formula: (CoFeXN1pHV)ZGloo
-2 or -y-p (CO1-x-y-p FexNipMy) ”100
-u (where M is -r;, v, Or, Mn, CLI, Z
r, Nb, Me, Ru, Rh, Pd, AQ, Hf, Ta
, W, Re, Pt, Au, Y, and a rare earth element; G represents B;
represents at least one element selected from the group consisting of C, s;, p, and Ge: T is Tr, Zr, Hf, V,
Represents at least one element selected from the group consisting of Nb, Ta, W, MOIY and rare earth elements: x, y,
p.

Z and U are O≦X≦1, O≦y≦0.2, O
It represents a number that satisfies the relationships: ≦p≦0.8.65≦Z≦90 and 85≦U≦95. ) is used.

Amorphous alloy powder having such a composition takes the form of powder, flakes, etc. Manufacturing methods include a method of pulverizing an amorphous alloy ribbon obtained by ordinary rapid cooling, and a method of obtaining powder from a molten alloy all at once, such as an atomization method. There is no particular limitation to this manufacturing method. The amorphous alloy powder thus obtained may be subjected to pretreatment such as autoclave treatment to form an oxide film.

The particle size of the magnetic powder is preferably about 300 μm or less, and about 10 μm or less.
Considering the application at high frequency of 0kHz or more, 100μ
It is preferable that the thickness is approximately 30 m or less, for example, 30 t1 m or less. If it is too small, the density will not increase, resulting in a decrease in magnetic density. Therefore, it is preferably 1 μm or more, usually about 10 to 300 μm.

Examples of the inorganic polymer used in the present invention include porsiloxane resin.

During production, inorganic polymers and silica are added to the solvent, and then the solvent is removed at about 150 to 250°C, depending on the magnetic powder.
By performing heat treatment under optimal conditions and curing at the same time, excellent magnetic properties can be obtained.In other words, according to the present invention, by using an inorganic polymer binder, heat treatment can be applied after molding. .

Although the inorganic polymer weight can be changed depending on the desired properties, it is usually preferably about 1 to 10 VOI%.

Further, in the case of an amorphous alloy, the heat treatment is performed at a temperature below the crystallization temperature.

Further, molding can be carried out by methods conventionally used for powder molding, such as explosive compression bonding and warm compression.

[Effects of the Invention] The powder magnetic core obtained by the present invention has excellent moldability, and can be particularly heat-treated, so that it can fully bring out the magnetic properties of the magnetic powder, such as high magnetic permeability and low iron loss. I can do it.

[Embodiments of the Invention] Using a single roll method, a (Fe
O,95Cr O,05)353! The particle size of the powder obtained after making the 3812 amorphous alloy was about 10 μm. Next, the amorphous alloy powder was immersed in a solution containing N-methyl-2-pyrrolidone (trade name: 5MR109 Showa Electric Cable) using an inorganic polymer and a polysiloxane resin as a solvent, and then It was molded into a ring-shaped core with a diameter of 1Qmm. The obtained core was heated at 150℃ for 2
0 minutes, heat treated at 250℃ for 30 minutes to evaporate the solvent,
A curing treatment was performed at 420° C. for 60 minutes.

The frequency characteristics of iron loss and magnetic permeability of the ring core were measured. The iron loss was 460 mW/ccr under the measurement conditions of an operating magnetic flux density of 3 kG and a frequency of 50 kHz.

When the frequency characteristics of magnetic permeability were measured, as shown in FIG. 1(a), it was as high as 700 at 1 kHz, and had excellent frequency characteristics.

In addition, the strength of the core was not a problem in practical use, and there was no change at all even when a 1 m drop test was performed.

For comparison, 42% of amorphous alloy powder with the same composition was prepared in advance.
It was heat treated at 0°C for 60 minutes, molded with epoxy resin into the same shape as the example, and cured at 150°C for 2 hours, and the frequency characteristics of iron loss and magnetic permeability were measured. The iron loss is 2300 (mW/CC) under the same conditions as the example, and the magnetic permeability is 1kHz.
It was extremely small at 20.

[Brief explanation of the drawing]

FIG. 1 is a curve diagram showing the magnetic permeability of amorphous alloy dust cores of the present invention and comparative examples.

Claims (1)

[Claims] A dust core characterized by being made of a compacted compact of magnetic powder using an inorganic polymer as an electrical insulator as a binder.