JPS62154604A - Permanent magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a permanent magnet having high coercive force of excellent shape anisotropy by utilizing the properties of acicular single crystal magnetic material precipitated in pores of anodic oxidation film of aluminum or aluminum alloy. CONSTITUTION:Pore diameter is controlled to a range of 80-400Angstrom and barrier layer film thickness is controlled to a range of 100-300Angstrom in a process for precipitating a ferromagnetic material in the pores of an anodic oxidation film of aluminum or aluminum alloy to precipitate single crystal acicular ferromagnetic material to form a magnetic material, thereby magnetizing the ferromagnetic material of this magnetic material. An anodeic oxidation is executed, for example, by applying a voltage and a current controlled at 20 deg.C with oxalic acid solution with aluminum alloy base material to form a film having pores, the material is then dipped in phosphoric acid path to enlarge the pores, thereby adjusting to 150Angstrom of pore diameter, 200Angstrom of cell diameter and 200Angstrom of barrier layer. Thus, the base material is electrolytically treated in Mohrs.. salt to precipitate ferromagnetic material in the pores, thereby forming a permanent magnet material.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical field to which the invention pertains The present invention provides a permanent magnet with high coercive force that utilizes the shape anisotropy of a ferromagnetic material deposited in a bore in an anodized film of Aluminum 1 or an aluminum alloy. The present invention relates to a magnet and a method for manufacturing the same.

Prior Art and Its Disadvantages Magnetic anisotropy refers to the property that the direction of easy magnetization is in a specific direction. A magnetic material having this property has a strong strength against the II and LA fields, that is, a large coercive force, and is therefore suitable as a permanent magnet material. The magnetic material utilizing shape anisotropy is better as the size ratio of a single magnetic material, that is, the ratio of the long axis to the short axis of the magnetic material is larger.

One example of a magnet that utilizes the shape anisotropy of ferromagnetic material is the Lad, which was announced by General Electric Company in the United States.
OX (the company's product name) is known, which is made by mixing acicular magnetic material deposited on a mercury negative electrode with a lead alloy, etc.
This is a magnet obtained by press molding.

The characteristics of this magnet have the advantage that magnets with accurate dimensions can be manufactured, but the diameter of the single magnetic body obtained is 500 to 10
,000λ, and the dimension ratio is about 5 at most, so the important thing is that the coercive force is as low as about 600 to 1.0000e. In addition, with the manufacturing method of the same magnet, it is difficult to disperse ferromagnetic particles, and the filling rate of ferromagnetic material is only about 50% at maximum.
Maximum energy product (B H) ■a! is up to 3 MG
Oe, and is not particularly excellent as a permanent magnet.

The problem to be solved The magnetic material precipitated in the bore of the anodic oxide film of aluminum or aluminum alloy has a much larger dimensional ratio than any other single magnetic material, and has a much better shape anisotropy. What? It has been pointed out that it is a magnetic material.

However, in what has been reported so far, the coercive force, which is an important magnetic characteristic of permanent magnet performance, has not necessarily been able to meet various practical needs. The conventional anodic oxide film of aluminum or aluminum alloy in which a magnetic material is deposited in the bore is considered to be used exclusively as a readable/writable magnetic recording material, and therefore is not suitable as the above-mentioned magnetic recording material. The dimensional ratio of a single magnetic material that satisfies the conditions, the processing conditions of anodization, bore enlargement, and magnetic material electrolytic deposition to obtain coercive force (applied voltage, processing time, barrier layer thickness, filling rate, etc.) Exploration of
This is because the setting was the subject of exclusive research and development, and it was not possible to explore the practical problems of using this as a permanent magnet.

Therefore - C1 The first invention according to this application is a permanent magnet that takes advantage of the shape anisotropy of the magnetic material deposited in the bore of alumite.

It is an object of the present invention to provide a permanent magnet having high coercive force due to particularly excellent shape anisotropy.

Moreover, the second invention and the third invention aim to provide two methods for producing a permanent magnet having an acicular single crystal magnetic material having excellent shape anisotropy and high coercive force. According to the second invention, an acicular single crystal magnetic material is deposited in the bore of an anodic oxide film of aluminum or an aluminum alloy, and the single magnetic material thus deposited has a particularly large size ratio and high resistance. Aiming to make it possible to provide high-performance permanent magnets using magnetic force, the third invention manufactures permanent magnets with excellent shape anisotropy using a single magnetic material having a large dimension ratio and high coercive force. The purpose is to provide other ways to

Means for Solving Problems In the groove of the present invention, the dimensional ratio of a single magnetic substance deposited in the bore of the anodic oxide film of aluminum or aluminum alloy can be determined by controlling the amount of electricity applied in the anodizing process.
It is possible to select any value from 50 to 1, and in a certain control electric i (8500Q), the size ratio of magnetic fine particles precipitated in the alumite bore reaches 50,000 at a film thickness of 500 l5. It was discovered that the material becomes a needle-like single magnetic material.

In addition, although the bore diameter can be freely controlled by the applied voltage during anodization, the inventor's experiments have confirmed that the value of the bore diameter greatly affects the coercive force of the permanent magnet. A suitable bore diameter for the permanent magnet material is 80 to 4. O
Since O is less than 1.0000e, it is not preferable as a permanent magnet.

Furthermore, when depositing ferromagnetic material into the alumite bore, a thicker barrier influences the shape and quality of the magnetic crystals that are deposited and grown, and is another important determining factor for the performance of permanent magnets. It was found that the maximum energy product is affected. By controlling the barrier layer thickness to 100 to 30 OA and using AC electrolysis, an acicular single-crystal ferromagnetic material can be obtained, which has particularly good shape anisotropy and a coercive force of up to 30,000. It also reaches e.

Even if the thickness of the barrier layer is less than xooi or more than 3ooi, it is possible to deposit a ferromagnetic material by controlling the pH of the electrolytic deposit using an appropriate reducing agent, but it is possible to deposit a ferromagnetic substance in the acicular particles. A good single-crystal ferromagnetic material cannot be obtained due to the incorporation of impurities such as ferromagnets, and as a result, the permanent magnet in this case has a low coercive force.

The filling rate of magnetic material in the bore is approximately 10% by volume in a normal alumite film that has undergone only anodizing treatment, but a maximum of 70% by volume can be easily achieved by performing bore enlargement treatment after anodizing treatment. .

In the case of Lodox mentioned above, since the acicular ferromagnetic material is dispersed in lead, lead alloy, resin, etc., the dispersion is not uniform or sufficient, so the filling rate of the ferromagnetic material is about 30% at maximum. On the other hand, in the alumite film, the lateral crystalline magnetic material is regularly precipitated one by one in the bore, so that it is evenly dispersed. Permanent magnets have a maximum energy product of 40
It also reaches M G Oe. This is comparable to permanent magnets made of rare earth or cobalt alloys.

Furthermore, since the permanent magnet according to the present invention is made by precipitating a magnetic material in a bore formed by anodizing treatment, it is possible to create a permanent magnet on the inner surface of an aluminum pipe, for example. For example, it can be applied to the production of specially shaped magnets that can be used in water treatment equipment that utilizes the magnetic field inside the vibrator.

As mentioned above, the invention of t51 utilizes all the characteristics of the acicular single crystal magnetic material deposited in the bore of the anodic oxide film of aluminum or aluminum alloy, so it has a high resistance with particularly excellent shape anisotropy. Since it can provide a permanent magnet with magnetic force and does not require expensive raw materials such as cobalt, it has great economic effects.

In addition, the second invention makes it possible to easily produce a high-strength permanent magnet by magnetizing a base material in which acicular single-crystal magnetic material is deposited in the bore of an anodic oxide film of aluminum or aluminum alloy. .

A permanent magnet that takes advantage of the excellent shape anisotropy and high coercive force of an acicular single-crystal magnetic material precipitated in the bore of an anodic oxide film of aluminum or aluminum alloy is the ferromagnetic material precipitation in the second invention. The subsequent anodic oxide film is dissolved in a phosphoric chromic acid solution to extract only the acicular single crystal ferromagnetic material, which is mixed with a binder such as lead or lead alloy, or synthetic resin, and solidified in a magnetic field. By press molding, it is also possible to manufacture a permanent magnet having the same performance as the permanent magnet according to the second invention.In addition, in the melting process of this manufacturing method, the surface of the acicular magnetic material is naturally oxidized. A protective film is formed.

Examples of this invention Next, the present invention will be explained in detail.

Example 1 An aluminum alloy base material was coated with 2% oxalic acid solution.
After anodizing under controlled voltage and current application at 0°C to produce a coating with bores, 1
% phosphoric acid bath for 10 minutes to enlarge the bore.
Bore diameter 150, cell diameter 200λ, barrier thickness 200
A, the base material was electrolytically treated in a 10% Mohr's salt solution, and a ferromagnetic material was deposited in the bore to form a permanent magnet material. Next, a magnetic field is applied to the permanent magnet material to completely remove the magnetizing force from the state of saturation magnetic flux density, and the saturation magnetic flux density Bs, residual magnetic flux density B' and coercive force He are measured, and the demagnetization curve is The maximum energy product (BH) wax was measured from the product of magnetic flux density and magnetizing force, and the results were as follows.

Bs: 12KG Br: 11.5KG Hc: 25000 e (B H) wax: 20MG Oe Under the same conditions as the above example, only anodizing treatment was performed, or bore enlargement treatment was performed afterwards, and magnetic material (Fe, Co) precipitation treatment was performed. However, here are the results of measuring the coercive force when only the bore diameter was different.

As shown in FIG.

Example 2 Anodizing treatment and bore enlargement treatment were carried out under the same conditions as in Example 1, and the bore diameter was adjusted to 150 mm, and the bore diameter was adjusted to 40 mm.
Two types of base materials were prepared, one adjusted to slightly more than 0λ, and each base material was electrolytically treated in a 10% Mohr's salt solution to precipitate a ferromagnetic material in the bore to obtain a permanent magnet material. . Then, in the same manner as in Example 1, the saturation magnetic flux density Bs
, the residual magnetic flux density Br and the coercive force He are measured, and the maximum energy product (
BH)+waz was measured.

When the barrier layer thickness is 200λ, the holding force Hc is 2700
0 e, whereas the holding force He when the barrier layer thickness is a little over 400 λ is 8000 e. In order to investigate the cause of this difference, we observed the growth state of the magnetic material precipitated in the bore using an electron microscope.As a result, when the barrier layer was 200A thick, as shown in attached photo 1, a high density acicular single crystal magnet On the other hand, in the case of 400λ or more, the precipitated magnetic material is needle-shaped, but it is composed of an aggregate of two or more types of fine particles and becomes a complete magnetic material. It turns out there isn't.

Other Bs, Br, and (BH)saw are almost the same as in Example 1.

Example 3 In the same manner as in Example 1, an acicular single-crystal magnetic material was precipitated in the bore of a model of alumite skin, and then it was placed in a phosphoric acid chromic acid solution (phosphoric acid 35 ccZ, chromic acid 30 g/text). The film was immersed in a liquid with a film thickness of 200°C for 10 minutes at a temperature of 40°C to extract only a single magnetic substance by dissolving the base material, collect the precipitated acicular magnetic substance, and transfer it to a thermosetting resin material. As an example, the mixture was mixed with vinyl chloride resin so that the proportion of the former was 30%, and the mixture was heated and pressed in a magnetic field to form a permanent magnet.

The measured values obtained from this permanent magnet by the permanent magnet test method according to JIS 02501 are as follows.

Bs: 8KG Br: 8KG Hc: 25000e (BH) mat + 5.0 MGOe Application examples of the permanent magnet of the present invention" As shown in the double series, the permanent magnet of the present invention has a bore of an anodized coating of aluminum or aluminum alloy. The second invention makes use of the excellent shape anisotropy and high coercive force of the acicular single crystal magnetic material precipitated therein, which are not found in conventional products. If a disk magnetized with a filled aluminum or aluminum alloy plate, or a disk prepared by mixing the acicular single crystal magnetic material extracted according to the third invention with a binder and magnetic field pressing is used in combination with a printed coil, , a thin electric motor can be manufactured. Such a motor is suitable for, for example, a thin magnetic disk driver.

Furthermore, since this magnetic disk has a particularly large coercive force, the recorded magnetic signal will not be erased by the magnetic field of a normal printed coil. Therefore, as illustrated in FIG. 2, the permanent magnet manufactured by the method of the present invention is magnetized so that different magnetic poles 2n and 2s are arranged alternately in the circumferential direction on a disk 1 to form a magnetic rotor. Moreover, by magnetizing and recording the rotational position or rotational angle detection signal 3 on the periphery, for example, it is possible to provide a new product in which the power source and the encoder are integrated.

Furthermore, since the direction of easy magnetization of the alumite magnetic film is perpendicular, it is possible to indicate the rotational position or rotational angle with high precision such as o- and i-pitch, so it is suitable for use in, for example, magnetic disk drive servo motors. It is.

[Brief explanation of drawings]

FIG. 1 is a characteristic graph showing the relationship between the bore diameter control range and coercive force according to the present invention, and FIG. 2 is a front view of a magnetic rotor which is an application example of the permanent magnet manufactured according to the present invention. Patent Applicant: Lawyer No. 2) Figure 2

Claims (3)

[Claims] (1) A permanent magnet that utilizes the shape anisotropy of an acicular single-crystal ferromagnetic material deposited in the bore of an anodic oxide film of aluminum or aluminum alloy. (2) In the process of depositing a ferromagnetic material in the bore of the anodic oxide film of aluminum or aluminum alloy, the bore diameter is 80 to 400 Å, and the barrier layer thickness is 100 to 3
1. A method for producing a permanent magnet, comprising: precipitating a single-crystal acicular ferromagnetic material to form a magnetic material, and magnetizing the ferromagnetic material of the magnetic material by controlling the ferromagnetic material within a range of 00 Å. (3) In the process of depositing a ferromagnetic material in the bore of the anodic oxide film of aluminum or aluminum alloy, the bore diameter is 80 to 400 Å, and the barrier layer thickness is 100 to 3
By controlling the thickness to a range of 00 Å, a needle-like single crystal ferromagnetic material is precipitated, and the anodic oxide film is etched with a phosphoric acid chromic acid solution to extract only the needle-like single crystal ferromagnetic material. Mixing a shaped single crystal ferromagnetic material with a binder,
A method for producing a permanent magnet characterized by solidifying in a magnetic field.