JPS5931006A - Composite soft magnetic material - Google Patents

Abstract

PURPOSE:To enhance permeability without using filaments by a method wherein flake-like soft magnetic materials are bonded by bonding materials. CONSTITUTION:Flake-like soft magnetic materials such as pure iron powder of mean grain size 100mum, for example, are rolled by a roll to be converted from the spherical form to the disc-like form. The rolled disc-like pure iron is cleaned and then annealed in hydrogen gas at 800 deg.C for 1hr. This disc-like pure iron is weighed to become 50vol% and knealed with epoxy resin. Thereafter, it undergoes press forming under pressure of 1ton/cm<2>. Subsequently, it is cured at 150 deg.C for 2hr and then drawn out into the ring-like form. In this way, by using the flake-like soft magnetic materials, it becomes possible to enhance permeability without using expensive soft magnetic materials such as filaments.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a soft magnetic material, and is characterized in that flaky soft magnetic material is bonded with a bonding material.

As is well known, soft magnetic materials can be roughly divided into two types: solid materials and composite materials. The solid type is made of a sintered body of gold*, an alloy, or an oxide, and does not contain a binder in the soft magnetic material. On the other hand, in the composite type, since the soft magnetic materials are small, the yoke shape cannot be formed unless they are hardened with a binding material.

Conventional composite soft magnetic materials include pure iron and Sendust.

It is made by bonding powders such as permalloy and permalloy with an inorganic binder such as glass or resin. The characteristics of its magnetic properties are: 1. The saturation magnetic flux density is proportional to the volume percent of the magnetic powder.2 The magnetic permeability is the reciprocal of the volume of the hollow space, and is extremely small, on the order of 1/100 to 1/10 of that of a solid.

3. Magnetic permeability is almost unaffected by the applied magnetic field and remains constant.

4. Due to low magnetic permeability, magnetic leakage is large. 5. The surface of magnetic particles is insulated, so electrical resistance is extremely high, and eddy current loss is significantly smaller than that of solid types.

etc. For this reason, it is widely used in high-frequency magnetic cores.

In the process of researching the magnetic properties of these composite soft magnetic materials, the author found that the difference between the magnetic permeability calculated from a structural model that assumes that magnetic particles are uniformly dispersed within the composite soft magnetic material and the actual value was determined. found that there was a large difference in

According to the structural model that assumes uniform dispersion of magnetic particles, the magnetic permeability/j C of the composite soft magnetic material is 1: the proportion of the space μi: the magnetic permeability of the magnetic material, and μi>>1, so 1, 1 becomes.

On the other hand, a composite soft magnetic material containing 50% by volume of pure iron powder was prototyped. Calculated and measured values of magnetic permeability are shown in Table 1.

As a result of pursuing the cause of this difference, it was discovered that the difference between the theoretical and measured values was that the dispersion of the magnetic particles was not uniform as in the model, but that the magnetic particles were continuous. In order to understand this phenomenon more correctly, we created a composite soft magnetic material using filament-like soft magnetic material and measured its magnetic permeability. As a result, we obtained a high magnetic permeability that could not be achieved with composite soft magnetic materials made of magnetic powder. was completed. For example, pure iron filament (length t/diameter d=100)
The magnetic permeability of the composite soft magnetic material containing 50% of C was 900.

However, turning soft magnetic materials into filaments requires many processing steps. Composite soft magnetic materials made of filamentary soft magnetic materials have good performance but have the disadvantage of high cost.

The present invention aims at cost reduction based on the above new knowledge regarding composite soft magnetic materials.

Examples will be given below to specifically explain.

Pure iron powder with an average particle size of 100 μm is rolled with a roll to form a spherical shape into a disk shape. The thickness of the disk is made 50.25 and 10.5μ by repeated rolling. In particular, multi-stage rolls were used for rolls of 10 μm or less. After rolling, it was washed and annealed in hydrogen gas at 800°C for 1 hour.

These disc-shaped pure irons are weighed so as to be 50% by volume, and epoxy resin is kneaded. Thereafter, it was press-molded at a pressure of 1 ton/cfl, and then cured at 150° C. for 2 hours.

A ring of 45 rtrm x 55 rtrm was cut out of a composite soft magnetic material made of press-formed disk-shaped pure iron, and its magnetic permeability was measured. The results are shown in Table 2. By turning spherical pure iron powder into a disk shape, the magnetic permeability is dramatically improved.

Table 3 shows a cost comparison of composite soft magnetic materials using filamentary soft magnetic materials.

(Note) Filamentary pure iron is made by cutting wire or using whiskers, and although it varies depending on the shape, it is 100 to 1000 times as much as granular pure iron and 50 to 5 times as much as circular pure iron.
Double the price.

The above embodiments describe only a portion of the invention.

Similar effects were obtained with other materials such as mild steel, silicon, hermalloy, and permenziel.

In addition, other molding methods include injection molding, compression molding with an inorganic binder, etc. In addition to rolling granules into a disc shape as a soft magnetic material that yields good results, rolling a long and thin rod shape is also possible. Even higher magnetic permeability was obtained.

In the present invention, the term "flake-like" refers to a lump formed into a flat shape by rolling or crushing. What is soft magnetic material?
Refers to a material with low coercive force and high saturation magnetic flux density. The binding material may be either a resin or an inorganic material. As the resin, nylon, polyethylene, polyester, phenol, vinyl chloride, acrylic, etc. can be used. Glass is suitable as an inorganic substance. The amount of binder is expressed in volume% [
1, 5, 1, 2, 5, 10, 20, 40, 60, 80%
experiment, the fabricated magnetic rate with small volume% increased by 1%
If it is less than 1%, moldability is poor, and 1% or more and 60% or less is an industrially valuable range.

The purpose of the present invention is to increase magnetic permeability by using a flake-like soft magnetic material without using an expensive soft magnetic material such as a filament, and has high practical value in engineering. It is.

This composite soft magnetic material is suitable for yokes with relatively complex shapes and high accuracy in beef dimensioning, and has a wide range of applications such as motors, tacho generators, speakers, and rad geometrical applications. Also insert molding.

Processing costs can be significantly reduced by outsert molding, multicolor molding, etc.

that's all

Claims (1)

[Claims] A composite soft magnetic material characterized by bonding flaky soft magnetic materials with a binding material.