JPH056523A - Magnetic recording body and production thereof - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and vibration resistance by sealing the pores of a magnetic film by a prescribed sealing material. CONSTITUTION:The magnetic film 3 for magnetic signal recording contg. Fe3O4 and FeO is formed by thermally spraying iron oxide powder to the surface of a base material 2. The sealing material 4 is applied on the surface of the magnetic film 3 to smooth the surface in order to close the pores opened on the surface thereof and thereafter, the surface layer is baked at 200 to 300 deg.C. The infiltration of oxidative materials into the pores in the magnetic film 3 is, therefore, prevented by the sealing material 4 and the corrosion of the magnetic film 4 or the base material 2 is prevented. The sealing material 4 serves as the buffer material when the magnetic film 3 vibrates. The peeling down of the individual magnetic particles is thus prevented. Since the vibration resistance is improved, this recording body is effectively used as a torque sensor for detecting the torque of a revolving shaft.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording body having a magnetic film for recording magnetic signals on a substrate and a method for producing the same.

[0002]

2. Description of the Related Art A technique of using a magnetic recording medium for detecting the torque of a rotary drive shaft, detecting the number of rotations, or detecting the rotation angle of an automobile or machine tool is generally known. That is, this technique forms a magnetic film as a magnetic recording medium on a base material, records a magnetic signal on the magnetic film, and reproduces the magnetic signal during use of the base material. The state of is detected.

Japanese Patent Laid-Open No. 61-53504 discloses a magnetic scale used in an encoder for detecting the number of revolutions, in which a hard magnetic quenched alloy ribbon is fixed to a plastic card to form a magnetic signal recording film. Forming,
The quenched alloy ribbon has a peripheral speed of 10 to 4 made of molten magnetic material.
It is disclosed to be jetted onto a copper wheel rotating at 0 m / s.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the corrosion resistance and vibration resistance of a magnetic recording medium having a porous magnetic coating formed by spraying magnetic particles onto the surface of a substrate. Especially. That is, in the case of the above porous magnetic film, when used in an oxidizing atmosphere, an oxidizing substance such as sulfur dioxide penetrates into the pores to corrode the interface between the magnetic film and the base material or the magnetic film itself, It causes peeling of the film.
Further, in an environment where mechanical vibration is applied as in the case of detecting the torque of the shaft-shaped member, there is a concern that the inter-particle bonding force of each magnetic particle forming the magnetic film is weakened by the vibration and partially peeled off. . Therefore, the present invention is intended to solve such a problem.

[0005]

SUMMARY OF THE INVENTION The present invention addresses the above problems by sealing the pores of a magnetic film.

That is, a magnetic recording medium for solving the above-mentioned problems has a magnetic film for recording a magnetic signal on a base material, and the magnetic coating is a porous material formed by thermal spraying of magnetic particles. And the pores formed on the surface of the magnetic coating are closed by a sealing material softer than the magnetic particles.

In this case, the base material may be magnetic or non-magnetic, and in the case of a magnetic base material, a non-magnetic film of Al, Cu, Ti or the like is formed as an underlayer. It is desirable to prevent the leakage of magnetic flux from the magnetic film on it to the substrate.

As the magnetic material for forming the magnetic film, iron oxide (Fe ₃ O ₄ or γ-Fe ₂ O ₃ or a mixed powder of these and FeO), cobalt, Fe, permalloy or the like can be used.

As the sealing material, a so-called binder containing an acrylic resin, an epoxy resin, polyvinyl alcohol, a phenol resin as a main component can be used.
Further, in order to improve the magnetic properties of the magnetic film, it is preferable to use a binder containing magnetic particles. As the magnetic particles in this case, a magnetic material that forms a magnetic film may be used, or a high magnetic permeability material such as permalloy, sendust, or soft ferrite may be used.

A preferred embodiment is to cover the entire surface of the magnetic film with the above-mentioned sealing material and form a surface layer having a smooth surface with this sealing material.

A preferred method for producing the above magnetic recording body is a step of spraying iron oxide powder on the surface of a substrate to form a magnetic film for magnetic signal recording containing Fe ₃ O ₄ and FeO. And a step of forming a surface layer having a smooth surface by applying a sealing material on the magnetic film to close pores opening on the surface of the magnetic film, and the surface layer having a thickness of 200 to 300.
And a step of baking at a temperature of ° C.

In this case, as the spraying method, plasma spraying, arc spraying, flame spraying can be adopted, or reduced pressure plasma spraying can also be adopted.

[0013]

In the above magnetic recording medium, the sealing material prevents the infiltration of the oxidizing substance into the pores of the magnetic film, and prevents the corrosion of the magnetic film or the substrate. Further, the sealing material serves as a cushioning material when the magnetic film vibrates, and prevents the individual magnetic particles from coming off.

In this case, the fact that the pore-sealing material is filled in the pores of the magnetic film is effective for preventing the above corrosion and improving the vibration resistance.

Further, the sealing material covers the entire surface of the magnetic film,
In addition, in a magnetic recording medium having a smooth surface layer, the surface of the magnetic film is prevented from being corroded, and the smooth surface can improve the S / N value.

Further, in the sealing material containing the magnetic material, the sealing material itself has a function as a magnetic recording medium to improve the reproduction output, or a high permeability material is used as the magnetic material. It becomes possible to promote the entry of a magnetic field into the magnetic film during recording of a magnetic signal and improve the recordability (writeability).

On the other hand, in the method of manufacturing the magnetic recording medium, the surface layer made of the sealing material is baked at a temperature of 200 to 300 ° C., so that the adhesion between the surface layer and the magnetic film can be increased. Fe ₃ O ₄ which has magnetism due to the fact that FeO in the magnetic film is oxidized by the heating during the above baking
And the magnetic characteristics of the magnetic film are improved.

[0018]

Therefore, according to the above magnetic recording medium, since the sealing material for sealing the pores of the magnetic film is provided, the corrosion resistance of the magnetic recording medium and the vibration resistance of the magnetic film can be improved, which is excellent for a long period of time. The magnetic characteristics can be maintained.

Further, according to the magnetic recording body in which the sealing material is filled in the pores, the above corrosion resistance and vibration resistance can be enhanced more effectively.

Further, according to the magnetic recording body having the smooth surface layer formed by the sealing material, the above-mentioned corrosion resistance and vibration resistance can be improved, and noise during reproduction can be suppressed.

Further, according to the magnetic recording body using the sealing material containing the magnetic material, the magnetic characteristics can be improved, and, for example, the reproduction output and the recording property can be improved.

According to the method for producing a magnetic recording medium, iron oxide powder is sprayed on the surface of the base material to form a magnetic film for magnetic signal recording containing Fe ₃ O ₄ and FeO. Since a sealing material is applied on the film to form a surface layer having a smooth surface, this surface layer is baked at a temperature of 200 to 300 ° C., so that the adhesion between the magnetic film and the surface layer is increased. While increasing the amount of Fe ₃ O ₄ in the magnetic film,
The reproduction output can be improved.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. In the magnetic recording body 1 shown in FIG. 1, 2 is a shaft-shaped base material made of carbon steel (JIS S45C), and a magnetic film 3 for recording a magnetic signal is formed on the surface thereof by a thermal spraying method. That is, the magnetic coating 3 is of iron oxide type, and has a large number of magnetic particles 3a deposited and deposited on the surface of the base material 2, and therefore has a large number of pores 3b. A sealing material 4 is embedded in the pores 3b.

The sealing material 4 is formed by mixing and dispersing magnetic particles in an organic binder, and imparts a binding force to the magnetic particles 3a, 3a of each magnetic coating 3. The main component of the organic binder is an acrylic resin solution. 25 magnetic particles
It is made of Fe ₃ O ₄ powder having a size of 0 mesh or less, and its ratio to the total amount of the sealing material is 5 to 30 wt%.

Next, a method for manufacturing the magnetic recording body 1 will be described. -Formation of magnetic coating- A plasma spraying apparatus using a plasma arc as a heat source was used to form the magnetic coating 3. The thermal spraying conditions are as follows, and the film thickness is 300 μm.

Thermal spraying material: 100% Fe ₃ O ₄ particles (particle size 10 to 63 μm) Output power: 32 KW gas pressure; Ar: 80 psi, H ₂ : 50 psi gas flow rate; Ar: 80 scfh, H ₂ : 15 scfh.

By the above thermal spraying, a magnetic film containing Fe ₃ O ₄ as a main component and a small amount of FeO is formed. A small amount of FeO is included because some Fe ₃ O ₄ particles are reduced in the process of thermal spraying.

-Impregnation with sealing material-Pretreatment In order to remove dust, oil and the like adhering to the magnetic film 3, degreasing treatment and washing treatment are carried out (to remove impurities).

The vacuum-treated magnetic recording medium 1 is placed in a container for performing vacuuming and pressurization and kept at 15 mmHg or less for about 15 minutes to remove air in pores between magnetic particles (impregnated with a sealing material. This is to make it easier).

Impregnation Treatment The pores of the magnetic film 3 are impregnated with a sealing material in the above container,
In addition, the sealing material is vibrated (to spread the sealing material to each part).

Pressure treatment The surface of the sealing material liquid is pressurized at 7 kg / cm ² for about 15 minutes in the above-mentioned container (to spread the sealing material to each part).

The liquid-draining magnetic recording medium 1 is taken out from the container, and the sealing material adhering to the surface is removed. Washing with water The sealing material on the surface of the magnetic film 3 is removed by washing with water.

Hardening treatment of the sealing material The magnetic recording body 1 was immersed in hot water at 90 ° C. or higher for about 15 minutes,
Sealing material (Acrylic resin is cured.

The magnetic recording medium 1 directly applies torque applied to a rotary drive shaft used in automobiles, industrial robots, etc.
Suitable for use as a highly accurate torque sensor.
In that case, magnetic pulse signals are circumferentially recorded in a magnetic layer formed over the entire circumference of the rotary drive shaft at two positions spaced apart in the axial direction of the rotary drive shaft, and the magnetic pulse signal is recorded in the circumferential direction during rotation of the rotary drive shaft. The magnetic signals at both positions can be read by a magnetic signal reading head, the torsion angle of the rotary drive shaft can be obtained from the phase shift amount of the magnetic signals at both positions, and the torque can be obtained therefrom.

Next, a test conducted to confirm the effect of the present invention will be described.

-Reproduction Output Evaluation Test- A plurality of types of test materials (Examples) having a base material of an Al alloy shaft having a diameter of 30 mm and different Fe ₃ O ₄ contents in the sealing material, and the sealing material. A test material (Comparative Example) not provided with was prepared. Each of these test materials has a magnetic film formed by the magnetic film forming step of the above-described manufacturing method, and the test materials of Examples are sealed based on the sealing material impregnation treatment step of the above-described manufacturing method. Pores were provided. Then, for each of the above test materials, recording and reproduction of magnetic signals were performed under the following conditions,
The reproduction output was measured.

Shaft rotation speed: 600 rpm (constant) Recording / reproducing head; Erasing head recording current; 0.4 A recording frequency; 1000 Hz Gap between head and shaft; 0 μm Note that an amplifier and a filter are not used during reproduction. It was The results are shown in Figure 2.

According to FIG. 2, among the test materials of the examples, those in which the Fe ₃ O ₄ content in the sealing material is zero have a lower reproduction output than the comparative example having no sealing material. ing. It is considered that this is because the sealing material became magnetic resistance and the recording property was slightly lowered. However, in the example in which Fe ₃ O ₄ was contained in the sealing material, the reproduction output was higher than that in the comparative example, and the reproduction output was also increased as the Fe ₃ O ₄ content was increased. ing. This is Fe in the sealing material
_{It is considered that 3} O ₄ increases the magnetic permeability of the sealing material and suppresses the following recording properties, and this Fe ₃ O ₄ functions as a magnetic recording medium.

-Corrosion resistance test- The structure of each sample material of the example and the comparative example is as follows.

Example 1 Carbon steel (JIS
A plate (60 mm long, 50 mm wide, 10 mm thick) according to S45C) was used. Then, a magnetic film having a thickness of 300 μm was formed on the surface of the base material by the above-described magnetic film forming step, and then a sealing material was provided by the sealing material impregnating treatment step.

Example 2 A shaft made of carbon steel (JIS S45C) having a diameter of 30 mm was used as a base material.
Then, a magnetic film having a thickness of 300 μm was formed on the peripheral surface of the base material by the above-described magnetic film forming step. Next, as a sealing material, Fe ₃ O ₄ powder (250
(A mesh or less) is mixed at a ratio of 3: 1,
This was spray-coated on the surface of the magnetic film. Then, using a rubber grindstone, the sealing material was rubbed into the pores of the magnetic film. In this case, the acrylic resin layer remains on the magnetic film in a thickness of about 10 μm or less (note that such a residue also occurs when other resins of different materials are used).

(Example 3) A test material was prepared in the same manner as in Example 2, except that an epoxy resin was used instead of the acrylic resin in Example 2 above.

Example 4 A test material was prepared in the same manner as in Example 2, except that a phenol resin was used instead of the acrylic resin in Example 2 above.

(Example 5) The same base material as in Example 2 was used, and a magnetic coating having a thickness of 200 µm was formed on the peripheral surface of this base material by the above-described magnetic coating forming step.
Next, as a sealing material, a mixture of phenol resin and Fe ₃ O ₄ powder (250 mesh or less) in a ratio of 3: 1 was used, and this was spray-coated on the surface of the magnetic film, and then the temperature of 250 ° C. The baking treatment was performed for about 60 minutes. The cross-sectional structure of the surface layer of the obtained test material is shown in Fig. 3.
Is shown in. That is, in the figure, 12 is a base material, 13 is a magnetic film, and 14 is a surface layer of a sealing material, and the surface of the surface layer 4 is formed smooth.

(Comparative Example) Carbon steel (JIS
S45C) board (length 60mm, width 50mm, thickness 1
0 mm) was used. Then, a magnetic film having a thickness of 300 μm was formed on the surface of the base material by the above-described magnetic film forming step. The impregnation treatment with the sealing material was not performed.

Then, for each of the above test materials, 100
Brine was sprayed in for 0 hours. Then, the presence or absence of peeling of the magnetic film in each test material was examined. In spraying the salt water, the test material is placed in a spray chamber kept at 35 ± 2 ° C, and sodium chloride solution (salt concentration 5 ±
A method according to JIS Z2371 of spraying and supplying 0.5%, PH 6.5-7.2) was adopted. The results are shown in Table 1.

[0047]

[Table 1]

According to Table 1 above, no peeling of the magnetic film occurred in any of the test materials of the examples. It is considered that this is because the sealing material prevented the invasion of salt water into the pores of the magnetic film.

-Film Strength Evaluation Test- The test material of Example 1 and the test material of the comparative example were prepared separately, and the interparticle bonding force in the magnetic coating was evaluated by the blast erosion test method shown in FIG. . In FIG. 4, 21 is a sample material, 22 is a blast nozzle, and 23 is a blast material. The test conditions are as follows.

Blast nozzle diameter: Diameter 5 mm Angle between blast direction and test material θ: 30 degrees Blast distance L; 100 mm Blast air pressure; 3.0 kg / cm ² Blast time; 10 seconds Results of the above test, Example In the test material of No. 1, the volume reduction of the magnetic film was about 90 mm ^{3 or} more, whereas in the case of the comparative example, the volume reduction was about 120 mm ^{3 or} less. It is considered that this is because the sealing material exhibited a cushioning effect.

Further, with respect to the fifth embodiment, the surface layer 14
After firing, it is desirable to grind or polish so that the thickness is as thin as possible. This is the surface layer 14
Although it contains magnetic particles, it becomes a magnetic resistance between the recording head and the magnetic film 13.

It is needless to say that the present invention can be used in other fields such as the measurement of the rotation angle and the number of rotations of the rotary shaft, in addition to the torque sensor described above.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic recording body.

FIG. 2 is a graph showing the difference in reproduction output due to the presence or absence of a sealing material and the difference in the content of magnetic particles in the sealing material.

FIG. 3 is a sectional view of a magnetic recording body having a surface layer.

FIG. 4 is a front view showing a blast erosion test method.

[Explanation of symbols]

1 Magnetic recording body 2,12 base material 3,13 Magnetic film 4 Sealing material 14 Surface layer made of sealing material

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshitsugu Ueoka             3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda             Within the corporation

Claims (5)

[Claims] 1. A magnetic recording body having a magnetic film for recording a magnetic signal on a base material, wherein the magnetic film is formed in a porous form by magnetic particles being deposited by thermal spraying. A magnetic recording medium characterized in that the pores open on the surface of the magnetic recording medium are sealed with a sealing material which is softer than the magnetic particles. 2. The magnetic recording medium according to claim 1, wherein the sealing material is filled in the pores of the magnetic film. 3. The magnetic recording medium according to claim 1, wherein the sealing material covers the entire surface of the magnetic film and forms a surface layer having a smooth surface. 4. The sealing material comprises a magnetic material.
The magnetic recording medium according to claim 3. 5. Fe _{3 is obtained} by spraying iron oxide powder onto the surface of a base material.
A step of forming a magnetic film for recording a magnetic signal containing O ₄ and FeO, and applying a sealing material on the magnetic film to close the pores opening on the surface of the magnetic film to smooth the surface. A step of forming a smooth surface layer,
And a step of baking at a temperature of 300 ° C.