JPH01184202A - Amorphous alloy powder for magnetic shield - Google Patents

Abstract

PURPOSE:To manufacture soft magnetic powder having easy-to-paint, good orientation property and excellent magnetic shield property by pulverizing amorphous alloy and making flasky shape specifying thickness, length and aspect ratio. CONSTITUTION:The amorphous alloy of Co base amorphous alloy (Co75Fe5Si4B16, etc.), Fe base amorphous alloy (Fe75Si10B15, etc.) etc., are pulverized with pulverizing method to manufacture the flasky shape soft magnetic powder having 0.1-10mum thickness, 1-50mum length and 3-100 aspect ratio (length/thickness). By this method, the amorphous alloy soft magnetic powder having excellent magnetic shield property, which can easily cover wall of building, room, box body or various kinds of parts, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective] The present invention relates to a flaky soft magnetic powder that is easily formed into a paint, has good orientation when applied, and has excellent magnetic shielding properties.

In recent years, electronic devices have become more susceptible to malfunctions and other problems caused by external magnetic fields such as the earth's magnetism, permanent magnets, and peripheral electronic devices. Furthermore, magnetic recording products such as magnetic cards and magnetic tapes often suffer from problems such as erasure of records due to similar external magnetic fields.

It has become essential to provide magnetic shielding to protect these products.

Magnetic shielding can be achieved by covering buildings, rooms, housings, parts, etc. with soft magnetic materials, and various methods are used, such as plate processing, coating methods, plating methods, etc. Among these methods, the coating method is said to be the simplest and most economical for complex shapes. However, in order to turn fine soft magnetic powder into a paint and obtain the desired magnetic shielding characteristics after application, it is necessary to increase the thickness of the film, which increases the number of man-hours such as repeating the application several times, which is economically disadvantageous. It becomes. This is because soft magnetic powders are fixed together via a binder, which increases magnetic resistance and decreases magnetic permeability.In order to provide magnetic shielding, the film thickness must be increased until a predetermined amount of magnetization is achieved. There is a need. As a result of intensive research, the present inventor has discovered that by making a magnetic amorphous alloy into flakes, the magnetic resistance can be reduced, and by taking advantage of the excellent properties of the amorphous alloy, a magnetic shielding material with excellent productivity can be obtained. I found out.

An object of the present invention is to provide a magnetic shielding powder for coating, which has excellent magnetic shielding properties against static magnetic fields and alternating magnetic fields, and has high productivity.

〔composition〕

The present invention relates to an amorphous alloy magnetic shielding powder for coating, which has a flaky shape with a thickness of 0.1 to 10 μm, a length of 1 to 50 μm, and an aspect ratio (length/thickness) of 3 to 100.

Amorphous alloys have attracted attention as various functional materials because they exhibit unique chemical and mechanical properties that are not found in ordinary crystalline alloys. Among them, amorphous alloys such as iron-based and cobalt-based alloys have no crystal anisotropy, and are therefore known to exhibit extremely good soft magnetic properties such as very small coercive force and high magnetic permeability.

By making this amorphous alloy into powder, other soft magnetic powders,
For example, Sendust, which is often used for this purpose,
It can be made into a magnetic powder with lower coercive force and higher magnetic permeability than powders of permalloy, stainless steel, etc.

If the composition of the amorphous alloy powder exhibits soft magnetism, it exhibits magnetic shielding properties.

Preferred composition examples of amorphous alloy powder in the present invention include C075Fe5Si4B+6+ Co6e, aFe4.
zSi++B+or CO7o, +Fe4. +Si+s
B+o+Co65FesSi+J+3+Co
66Fe5CrqSisB+s I Co7eSi+o
B+z+CoqoZr+.

Co-based amorphous alloy composition typified by (the suffix indicates atomic %; the same applies hereinafter), or Fe7sslloI
3+s+pe? 8stJ+3. Fe
ri eSi+oB+z +Fe7qSisB+ 6 +
F e+zCOaSi 5B+s + F
et6Cr 6SiJz+Few6MO6SitB+a
+ Fe7bCr6Nb+5L4B+a+Fea+5
itB+:+Cz+FebJi+bSieB+4
+Fe2:1NisssilOB12 +Fe
[1OP13G? +Fe7oCr+oP+:
+C7+FezoNi6oP+oB+o + Feqo
Fe-based amorphous magnetic alloys such as Zr+o+ can be used. The thickness of this amorphous alloy powder is 0.
When it is less than 1 μm, the coercive force of the powder increases and it becomes 10 μm.
Since the aspect ratio of the coating powder becomes small if the thickness exceeds 0.1 to 10 μm. A particularly preferred thickness is 0.5 to 3 μm.

Next, if the maximum length of the powder is less than 1 μm, the coercive force will increase, and if it exceeds 50 μm, it will be difficult to form it into a paint, so this length is set to 1 to 50 μm. Particularly preferred is 5 to 20 μm.

Amorphous alloy powder has no crystalline anisotropy and has low coercive force and high magnetic permeability, but by forming the powder into flakes instead of lumps, shape anisotropy is imparted and the magnetic resistance after application is reduced. Since the purpose of the present invention is to
thickness) is important.

If this aspect ratio is less than 3, it is difficult to reduce the magnetic resistance after coating, and the amount of coating needs to be increased, which becomes uneconomical. If it exceeds 100, it becomes difficult to orient the powder during coating. Since it becomes difficult to reduce magnetic resistance, this aspect ratio is set to 3 to 100. Particularly preferred is 10-30. Manufacturing methods for amorphous alloy powder include solid phase methods such as sputtering,
A method for producing powder (Japanese Patent Application Laid-Open No. 60-39106) and a cavitation method (Japanese Patent Application Laid-Open No. 58-1989) that the present applicant previously applied
Although various methods have been proposed, such as methods for directly producing powder from molten metal such as No. 6907), a pulverization method is industrially most preferred for producing powder of the size of the present invention. However, there is a method of applying heat to cause structural relaxation and then crushing (Japanese Patent Laid-Open No. 55-128506), and a method of charging hydrogen to cause embrittlement and then crushing (Japanese Patent Laid-Open No. 56-87610).
In this case, the powder of the present invention is difficult to obtain and becomes lumpy.

As a production means for obtaining the powder of the present invention, Japanese Patent Application No. 58-038
Possible methods include the method proposed in Japanese Patent No. 942 in which surface exfoliation is achieved by crushing the powder together using a jet stream, or the stamp mill method in which the powder is pulverized while being plastically deformed.

Example I A powder of 100 to 500 μm was prepared from the composition of C06B, aFen, and zSi I 78I O by the cavitation method, and this powder was further pulverized with a jet mill to obtain 1
A powder of 5 μm or less was obtained. This powder has a thickness of 0.5 to 3
．． The diameter was 0 μm, and the length was 3 to 15 μm.

This powder was made into a paint using acrylic resin and applied onto a PVC film to form a plate-shaped magnetic shielding material.

The magnetic shielding properties of this plate-shaped magnetic shielding material were examined using the apparatus shown in FIG. That is, a magnetizing coil 5 wound around an electromagnetic copper plate (silicon steel plate) core 4 is used as a magnetic field source, and an excitation current is supplied to the magnetizing coil 5 to generate magnetic flux 6, which passes through the plate-shaped magnetic shielding material 1. The strength of the leakage magnetic flux was measured at a distance of 100 mm from the end of the core 4 (indicated by 11 in the figure).

), and the magnetic shielding properties are evaluated based on the measurement results. The plate-shaped magnetic shielding material 1 is located between the core 4 and the detection coil 7 at a position 1511 from the detection coil 7 (indicated by 12 in the figure). Furthermore, by changing the excitation current supplied to the magnetizing coil 5, the strength of the magnetic field formed by the magnetic flux 6 is changed.

Using the apparatus shown in FIG. 1, the power supplied to the magnetizing coil 5 is DC, and the applied weight of the amorphous alloy powder per unit area of the plate-shaped magnetic shielding material 1 is changed.
The leakage magnetic flux passing through was measured. In this example, the applied magnetic field is IG.

The results are shown in FIG.

For comparison, a film coated with powder of the same composition having an average particle size of 10 μm and an aspect ratio of 3 or less in a similar manner was measured. As shown in Figure 2, there are large differences in magnetic shielding properties even when powders with the same composition are used. By increasing the aspect ratio, magnetic resistance is reduced and magnetic shielding properties are improved, making it possible to achieve properties close to those of a thin ribbon of the same composition by coating.

Example 2 An amorphous alloy ribbon having a composition of Fe7eSi+Jq was made into a powder of 50 to 200 μm in an impact mill, and further ground in a stamp mill to obtain a powder of 20 μm or less. This powder has a thickness of 0
．． The powder had a diameter of 2 to 2 μm and a length of 3 to 20 μm (see FIG. 3). This powder was made into a paint using an acrylic resin in the same manner as in Example 1, and was applied onto paper to form a magnetic shielding material.

This magnetic shielding material was measured at DC
The leakage magnetic field was measured in an applied magnetic field of 300G. For comparison, a coated paper similarly prepared using a powder having the same composition and an aspect ratio of 3 or less was also measured. As the results are shown in FIG. 4, it can be seen that good shielding characteristics are exhibited.

〔effect〕

The present invention can expand the field of application of magnetic shielding materials that can be applied. Furthermore, by being able to easily apply the magnetic shielding material, it becomes possible, for example, to create guides using the magnetic shielding material on roads, corridors, etc., and use it as guides for unmanned cars and blind people.

[Brief explanation of the drawing]

Figure 1 is a side view of the device used in the magnetic shield evaluation method, Figure 2 is C0611,8Fea, z'si I
Figure 3 shows the shielding characteristics of the 78I O composition.
Ew. An electron micrograph showing the particle structure of the Si, 38g composition, and FIG. 4 is a diagram showing the shielding characteristics of the Fe7eSi 1 3B9 composition. In the diagram: 1-----------------Electromagnetic shielding material 4-
−−−−−−−−−−−−−Electromagnetic steel core 5−−
−−−−−−−−−−−− Electromagnetic coil 6−−−−−−
−−−−−−−−Electromagnetic flux 7−−−−−−−−−−−−
---Detection coil agent Hideaki Kuwahara, patent attorney Figure 2: 91 m2 per 4W on the grass side (Fig. 4).゛He, ゝ, bite ~~ noise \ sound \ ~ in the book
〜＼shiko#eiireshin

Claims (1)

[Claims] A magnetic shielding amorphous alloy soft magnetic powder for coating having a flake shape with a thickness of 0.1 to 10 μm, a length of 1 to 50 μm, and an aspect ratio (length/thickness) of 3 to 100.