JP2003059741A - Manufacturing method of rare earth-based permanent magnet having deposition film on surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a rare earth-based permanent magnet for forming a uniform deposition film as a corrosion-resistant film having excellent coherency on the surface stably, without generating cracks and cutout during manufacture and deteriorating magnetic characteristics. SOLUTION: The manufacturing method should include a process for forming a deposition film on the surface of an aging treatment body, by performing deposition treatment to an aging treatment body after a rare earth-based permanent magnet sintering body having a desired composition is subjected to cutting machining and/or grinding machining, and an obtained machining body is washed for carrying out aging treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can prevent the occurrence of cracks and cracks in magnets and deterioration of magnetic properties during the manufacturing process.
The present invention relates to a method for producing a rare earth-based permanent magnet capable of stably forming a vapor-deposited coating as a corrosion-resistant coating having excellent uniformity and adhesion on its surface.

[0002]

2. Description of the Related Art Rare-earth permanent magnets such as R-Fe-B permanent magnets typified by Nd-Fe-B permanent magnets have high magnetic properties and are used in various fields today. There is. However, the rare earth-based permanent magnet contains a metal species (especially R) that is easily oxidized and corroded in the atmosphere. Therefore, when it is used without surface treatment, corrosion progresses from the surface due to the influence of slight acid, alkali and moisture, and rust occurs, which causes deterioration and dispersion of magnetic properties. It will be. Further, when rust is generated in a magnet incorporated in a device such as a magnetic circuit, the rust may scatter to contaminate peripheral parts. In view of the above points, vapor deposition coatings, particularly metal vapor deposition coatings such as aluminum and titanium are formed on the surface of the rare earth permanent magnet for the purpose of imparting excellent corrosion resistance. In particular, the aluminum vapor-deposited film has excellent corrosion resistance and mass productivity, as well as excellent adhesion reliability with the adhesive required when assembling parts (by the time the adhesive reaches the breaking strength inherently). (Peeling is less likely to occur between the coating and the adhesive)
Therefore, it is widely applied to rare earth-based permanent magnets that require strong adhesive strength. Here, as the adhesive, epoxy resin type, phenol resin type, reactive acrylic resin type, modified acrylic resin type (ultraviolet curable adhesive or anaerobic adhesive), cyanoacrylate type, silicone resin type,
Emulsion of various resin adhesives such as polyisocyanate-based, vinyl acetate-based, methacrylic resin-based, polyamide-based and polyether-based, and various resin-based adhesives (for example, vinyl acetate resin-based adhesives and acrylic resin-based adhesives) Mold adhesives, various rubber-based adhesives (for example, nitrile rubber-based adhesives, polyurethane rubber-based adhesives, etc.), ceramics adhesives, etc. are appropriately selected and used according to purposes such as heat resistance and impact resistance. .

A rare earth-based permanent magnet for forming a metal vapor deposition coating on its surface is usually manufactured as follows. That is, first, a rare earth-based permanent magnet raw material alloy powder having a desired composition is pressure-molded in a magnetic field to form a compact, and this is sintered to obtain a sintered body. Generally, the sintering of the molded body is performed at 900 ° C. to 1200 ° C. in an inert gas atmosphere such as argon gas or a reducing gas atmosphere such as hydrogen gas, or in vacuum.
It is carried out at 30 ° C. for 30 minutes to 8 hours. Next, the rare earth-based permanent magnet sintered body having the desired composition thus obtained is subjected to an aging treatment for retaining desired magnetic properties. Generally, the aging treatment of the sintered body is carried out in an inert gas atmosphere such as argon gas or in a reducing gas atmosphere such as hydrogen gas, or in vacuum at 450 ° C. to 900 ° C. for 5 minutes to 4 minutes.
It will be held for 0 hours. Next, the aging-treated body thus obtained is subjected to cutting processing or grinding processing to obtain a processed body having a predetermined shape having a predetermined dimensional accuracy. At this time, for example, Japanese Patent Laid-Open No. 2001-2001
As described in JP-A-25967, by using a cooling liquid (grinding liquid), it becomes possible to improve processing efficiency and processing accuracy. The cooling liquid is used to cool the processed part during cutting and grinding, and it contains water as the main component and contains a surfactant or synthetic type synthetic lubricant, organic rust preventive agent, non-ferrous metal. Those containing an anticorrosive agent, an antiseptic agent, an antifoaming agent, etc. are generally used.
After performing the cutting process or the grinding process, the workpiece is washed using a cleaning liquid to remove the cooling liquid remaining on the surface of the workpiece and to remove the shavings adhering to the surface of the workpiece. As the cleaning liquid, one containing water as a main component and an organic rust preventive agent containing alkanolamine represented by ethanolamine as a component is generally used. Finally, a blast treatment is performed on the processed body obtained as described above. Normally, as a pre-process of forming a metal vapor deposition film, the surface of the workpiece is subjected to surface cleaning treatment such as sputtering.However, such treatment alone can be used for cooling liquid and cleaning used during cutting and grinding. This is because components derived from the used cleaning liquid, for example, water and alkanolamine, which is an organic rust preventive component, may remain on the surface of the processed body and adversely affect the subsequent vapor deposition process. When vapor deposition is performed with water or organic rust preventive components remaining on the surface of the processed body, the remaining components as described above vaporize and adversely affect the formation of the metal vapor deposition coating, resulting in uniform and adherence. It becomes impossible to form a vapor-deposited metal coating excellent in heat resistance.

[0004]

As described above, the blasting process performed as the final step for producing a rare earth-based permanent magnet is an indispensable step. Generally, this step involves stirring the magnet in a barrel processing chamber or the like. However, there is a risk of cracking or chipping of the magnet. In addition, it cannot be denied that if the medium used for the blast treatment is not completely removed from the surface of the processed body, it may adversely affect the adhesion of the metal vapor deposition coating formed on the surface of the processed body. A method of volatilizing and / or decomposing and removing the residual components on the surface of the processed body by performing high-temperature heat treatment instead of the blast treatment is conceivable, but if this method is adopted, the process becomes complicated. In addition, according to the studies conducted by the present inventors, the processed body must be heated at a high temperature of 500 ° C. or higher in order to completely remove the residual components by this method. It is difficult to adopt this method because heating at such a high temperature may cause deterioration of magnetic properties. Therefore, in the present invention, it is possible to stably form a vapor-deposited coating as a corrosion-resistant coating that is uniform and has excellent adhesiveness on the surface thereof without causing cracking and chipping of the magnet or deterioration of magnetic characteristics during the manufacturing process. It is an object of the present invention to provide a method for manufacturing a rare earth-based permanent magnet that can be manufactured.

[0005]

In view of the above points, the present inventors have reviewed the process for preparing a rare earth-based permanent magnet on which a metal vapor deposition film is formed, and as a result, the blasting process as the final process thereof. The inventors have found a method capable of forming a metal vapor-deposited coating as a corrosion-resistant coating having excellent uniformity and adhesion on the surface thereof without performing high-temperature heat treatment.

The present invention has been made based on the above findings, and a method for producing a rare earth-based permanent magnet having a metal vapor-deposited coating on the surface of the present invention is, as described in claim 1, a rare earth of a desired composition. System permanent magnet sintered body and / or
Alternatively, a step of forming a vapor-deposited coating on the surface of the aging-treated body by performing grinding processing, washing the obtained processed body, and then performing aging treatment, and then performing vapor deposition treatment on the obtained aging-treated body It is characterized by including. The manufacturing method according to claim 2 is characterized in that, in the manufacturing method according to claim 1, the vapor deposition coating is a vapor deposition coating made of aluminum, titanium, or an alloy containing aluminum and / or titanium.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A method for producing a rare earth-based permanent magnet having a vapor-deposited coating on the surface of the present invention is a cutting product obtained by cutting and / or grinding a rare earth-based permanent magnet sintered body having a desired composition. And then performing an aging treatment, and then performing a vapor deposition treatment on the obtained aging-treated body to form a vapor-deposited coating film on the surface of the aging-treated body. .

Hereinafter, the method for producing a rare earth-based permanent magnet having a vapor-deposited coating on the surface of the present invention will be described step by step, taking as an example the case of producing a rare-earth permanent magnet having a metal vapor-deposited coating on the surface.

First, a rare earth-based permanent magnet raw material alloy powder having a desired composition is pressure-molded in a magnetic field to form a compact, and this is sintered to obtain a sintered body. This step itself may be performed according to a method usually performed, and sintering of the molded body is performed in an inert gas atmosphere such as argon gas or in a reducing gas atmosphere such as hydrogen gas, or in vacuum at 900 ° C to 1200 ° C. As described above, it may be performed for 30 minutes to 8 hours.

Next, the obtained rare earth-based permanent magnet sintered body having a desired composition is cut or ground to obtain a processed body having a predetermined shape with a predetermined dimensional accuracy. Here, for the cutting process, an outer peripheral blade cutting machine, an inner peripheral blade cutting machine, a wire saw, or the like for cutting out individual pieces from a block-shaped sintered body or obtaining a desired dimension is used. For the grinding process, a single-sided grinder or a double-sided grinder for obtaining a desired thickness dimension, a barrel grinder such as a rotary barrel or a centrifugal barrel for chamfering the sintered body is used. As described above, it is desirable that the cutting process and the grinding process be performed using a cooling liquid to cool the processed part. As the cooling liquid, water is the main component,
A mixture of a surfactant or a synthetic synthetic lubricant, an organic rust preventive, a non-ferrous metal anticorrosive, a preservative, an antifoaming agent and the like is generally used.

Next, the workpiece having a predetermined shape and having a predetermined dimensional accuracy obtained by cutting or grinding is washed to remove the cooling liquid remaining on the surface of the workpiece and the shavings adhering to the surface of the workpiece. . Cleaning of the processed body may be performed according to a conventional method. For example, the processed body is housed in a rotary barrel processing chamber, and the barrel containing the processed body is immersed in a cleaning tank and rotated in the cleaning tank to clean the processed body. Wash with stirring,
By performing ultrasonic cleaning, efficient cleaning becomes possible. As described above, as the cleaning liquid, a liquid containing water as a main component and an organic rust preventive agent containing alkanolamine represented by ethanolamine as a component is generally used. This is to prevent corrosion of the processed body as much as possible during and after cleaning the processed body. There is no particular limitation on the drying method after washing the processed body, but if a large amount of water remains on the surface without being sufficiently dried, an excessive oxide layer or water may be added during the aging treatment performed thereafter. An oxide layer may be formed on the surface, and these may lead to the obstruction of the adhesiveness of the metal vapor deposition film formed by the vapor deposition process. Therefore, in order to prevent such a situation, it is desirable to remove water effectively and reliably by performing physical removal of water at the same time by centrifugal force or high-pressure gas injection using compressed air or the like.

Next, an aging treatment is performed on the processed body washed as described above. Aging treatment for retaining desired magnetic properties is generally performed in an inert gas atmosphere such as argon gas or a reducing gas atmosphere such as hydrogen gas,
Alternatively, it is carried out in vacuum at 450 ° C. to 900 ° C. for 5 minutes to 40 hours. This condition is effective even if water or alkanolamine which is an organic rust inhibitor component remains on the surface of the processed body. Since it is a high-temperature heating condition sufficient for volatilization removal and / or decomposition removal, the surface of the processed body is cleaned at the same time as the aging treatment. The aging treatment is not limited to the one-step aging treatment as described above, and may be a multi-step aging treatment of two or more steps. The multi-step aging treatment is generally performed in an inert gas atmosphere such as argon gas or in a reducing gas atmosphere such as hydrogen gas, or in vacuum at a temperature of 800 ° C. to 90 ° C. as the first step aging treatment.
30 minutes ~ 6 hours at 0 ℃, 400 ℃ after the second stage aging
It is carried out at 750 ° C. for 2 hours to 30 hours.

Finally, a vapor deposition process is performed on the aging treated body obtained as described above. As a vapor deposition processing method,
From the viewpoint of the denseness of the metal vapor-deposited coating to be formed, the uniformity of the film thickness, the rate of film formation, etc., it is desirable to adopt the vacuum vapor deposition method or the ion plating method. As a pre-process for forming the metal vapor deposition coating, a surface cleaning treatment known per se may be performed on the surface of the aged body by sputtering or the like. Although there are no particular restrictions on the vapor deposition treatment conditions, it is desirable to set the temperature of the aging treated body at the time of film formation to 100 ° C to 500 ° C. If the temperature is lower than 100 ° C, a metal vapor deposition film having excellent adhesion to the surface of the aged body may not be formed, whereas if it exceeds 500 ° C, cracks may occur in the metal vapor deposition film during the cooling process after the film formation. This is because the coating may be peeled off from the magnet and the magnetic characteristics may be deteriorated. When the film thickness of the metal vapor deposition film formed by such a method is less than 0.01 μm, the film itself may not exhibit excellent corrosion resistance.
If it exceeds 0 μm, not only the manufacturing cost may increase, but also the effective volume of the magnet may decrease.
Therefore, the film thickness is preferably 0.01 μm to 50 μm, more preferably 0.1 μm to 25 μm, and 1 μm to 1 μm.
5 μm is more desirable. The metal vapor-deposited film formed by such a method forms a strong bonding layer with a rare earth element in a rare earth-based permanent magnet and has excellent adhesion, aluminum, titanium, and an alloy containing these metal components (for example, , Aluminum-magnesium alloy, titanium-
Vapor-deposited coatings composed of nickel alloys, titanium-copper alloys, etc.) are suitable. After forming the metal vapor deposition film, a peening treatment known per se may be performed on the metal film, or another film may be laminated on the surface of the metal film.

The vapor-deposited coating in the present invention is not limited to a metal vapor-deposited coating, but may be a ceramic vapor-deposited coating (for example, a vapor-deposited coating made of aluminum oxide, aluminum nitride, titanium oxide, titanium nitride, titanium carbide, etc.). The same effect can be expected.

According to the method for producing a rare earth-based permanent magnet having a vapor-deposited coating on the surface of the present invention, the surface of the processed body which has been conventionally used as the final step of preparing a rare-earth-based permanent magnet for forming the vapor-deposited coating on the surface thereof. No blasting is required for cleaning the. Therefore, it is possible to prevent the occurrence of cracking and chipping of the magnet in the middle of manufacturing, and since it does not heat at a high temperature after the aging treatment, it does not lead to deterioration of magnetic properties, and as a corrosion-resistant coating excellent in uniformity and adhesion. The vapor-deposited coating can be stably formed on the surface.
The surface of the rare earth permanent magnet has an average crystal grain size of 1 μm.
It is formed of a main phase composed of a compound having a tetragonal crystal structure in the range of m to 80 μm and a rare earth element rich phase, but the surface of the processed body that has been cut or ground is soft and rare earth element rich. It is considered that the phase is spread and the ratio of the rare earth element-rich phase on the surface of the processed body is increased. Conventionally, since the blast treatment is performed on the processed body having the rare earth element-rich phase spread on the surface, the spread rare earth element-rich phase may be separated from the surface. On the other hand, according to the method for producing a rare earth-based permanent magnet having the vapor deposition coating on the surface of the present invention, the vapor deposition treatment is performed on the processed body having the rare earth element-rich phase spread on the surface. Aluminum or the like originally has the property of forming a vapor-deposited coating having excellent adhesion on the magnet surface with a rare earth element on the magnet surface and a strong bonding layer, but in the present invention, it was spread on the surface. It is considered that performing the vapor deposition treatment on the processed body having the rare earth element-rich phase contributes to further improving the adhesion between the magnet surface and the aluminum vapor deposition coating.

[0016]

The present invention will be described in more detail by the following examples, but the present invention is not limited to the following description.

Example 1 (Production of Rare Earth Permanent Magnet) Step 1: 14 Nd-79Fe-6B-1Co Composition (at
%) After crushing the cast ingot and then finely crushing the resulting alloy powder into a molded body by pressure molding in a magnetic field,
This was sintered in an argon gas atmosphere at 1100 ° C. for 2 hours to obtain a sintered body of 55 mm × 45 mm × 8 mm. Step 2: The obtained sintered body was cut with a peripheral cutting machine. At this time, a 2 wt% aqueous solution of JP-04 / 97N (manufactured by Castrol Co.) containing organic acid salts, alkanolamines and the like as components was used as the cooling liquid. Subsequently, the obtained cut body was ground in a rotary barrel processing chamber using an abrasive having a JIS grain size of # 150 and 10φ alumina balls as a grinding medium. At this time, TKX containing organic acid salt, alkanolamine, etc. as a rust preventive agent
A 10 wt% aqueous solution of compound # 807B (manufactured by Kyoeisha Chemical Co., Ltd.) was used. Step 3: After removing the obtained processed body from the rotary barrel polishing machine, it is housed in a rotary barrel processing chamber used for barrel plating and the like, the barrel is immersed in a cleaning liquid, and the processed body is stirred by rotating the barrel. Washed while. At this time, a 2% by volume aqueous solution of PC-120 (manufactured by Fuso Chemical Industry Co., Ltd.) containing ethanolamine as a component was used as a cleaning liquid. After that, the drying temperature is 100 ° C and the maximum rotation speed is 5
The processed body was dried under a centrifugal drying condition of 00 rpm. Step 4: The washed and dried processed body is subjected to an aging treatment in an argon gas atmosphere at 550 ° C. for 1 hour to obtain 14N.
6 mm x with d-79Fe-6B-1Co composition (at%)
4.8 mm × 8 mm: test piece of rare earth permanent magnet having a surface area of 2.304 cm ² (hereinafter, abbreviated as magnet body test piece)
Got

(Measurement of amount of gas released from magnet test piece) High-accuracy thermal desorption gas analyzer (EMD manufactured by Electronic Science Co., Ltd.)
-WA1000S) was used as follows.
One magnet body test piece is housed in the device and the inside of the device is 3 × 1
After reducing the pressure to ^0-7 Pa or less, room temperature to 600
The temperature was raised to 0.5 ° C./second at 0.5 ° C./second, and the amount of released gas was measured. The results are shown in Table 1. In addition, in the table, "amount of released gas (total)" means the amount of all kinds of released gas. The "amount of released gas (M / z = 28)" means the amount of the released gas having a detected fragment ion mass / ion valence of 28, which is an alkanol contained in a cooling liquid, a rust preventive, or a cleaning liquid. It has been found from the analysis results that it is caused by C ₂ H ₄ ⁺ ions derived from amine.

(Formation of aluminum vapor-deposited coating on the surface of a magnet test piece) Vapor deposition apparatus (with a vacuum chamber having a volume of 2.2 m ³
Inside the vacuum chamber, there are two cylindrical barrels made of stainless steel mesh wire with a diameter of 355 mm and a length of 1200 mm, which are parallel to each other. The cylindrical barrel is rotated and the wire-shaped metal vapor deposition material is melted and evaporated. Which can be vapor-deposited while being continuously supplied to the apparatus: JP 2001-3206A
(The same configuration as in FIG. 1 of Japanese Patent Publication No. 2), 9000 magnet test pieces are accommodated in each cylindrical barrel, and 18000 magnet test pieces in total are accommodated in two cylindrical barrels. Was evacuated to 1.0 × 10 ⁻³ Pa or less,
Argon gas was introduced so that the total pressure in the vacuum chamber was 1 Pa. Thereafter, while rotating the rotation axis of the barrel at 1.5 rpm, sputtering by glow discharge was performed for 15 minutes under a bias voltage of -500 V to clean the surface of the magnet test piece. Next, set the barrel rotation axis to 1.
While rotating at 5 rpm, an aluminum wire was used as a vapor deposition material under the conditions of an argon gas pressure of 1 Pa and a bias voltage of -100 V, which was heated to be ionized.
An aluminum vapor deposition film was formed on the surface of the magnet body test piece by the ion plating method for 5 minutes. Regarding the aluminum vapor-deposited film formed on the surface of the magnet body test piece, visual appearance observation (n = 10), and those that passed the appearance observation were measured by a fluorescent X-ray film thickness meter (SFT-70 manufactured by Seiko Instruments Inc.).
00) was used to measure the film thickness (n = 10). The results are shown in Table 1.

(Peening treatment of vapor-deposited aluminum film) A magnet test piece having the vapor-deposited aluminum film obtained on the surface as described above was put into a blasting machine, and a blasting material was added together with a pressurized gas consisting of N ₂ gas. Glass beads (manufactured by Shinto Blator Co., Ltd .: GB-AG)
Was sprayed for 15 minutes at a projection pressure of 0.2 MPa to perform shot peening. Visual observation of the appearance of the vapor-deposited aluminum film subjected to shot peening (n
= 10), and the temperature of 80 for those that have passed the appearance observation.
Accelerated corrosion resistance test (n: left for 500 hours under high temperature and high humidity conditions of 90 ° C x 90% relative humidity) to observe the presence or absence of rust
= 10). The results are shown in Table 1.

Comparative Example 1 (Manufacture of Rare Earth Permanent Magnet) A sintered body was obtained in the same manner as in Step 1 of Example 1, and an aging treatment was performed in the same manner as in Step 4, and the same as in Step 2. After obtaining the processed body which has been subjected to the aging treatment, washing it in the same manner as in the step 3 and then drying it,
A magnet body test piece having the same composition and dimensions as the magnet body test piece obtained in Example 1 was obtained.

(Measurement of the amount of gas released from the magnet test piece) The amount of gas released from the magnet test piece was measured in the same manner as in Example 1. The results are shown in Table 1.

(Formation of Aluminum Vapor Deposition Coating on Magnet Body Specimen Surface) An aluminum vapor deposition coating was formed on the surface of the magnet body specimen as in Example 1. With respect to the aluminum vapor-deposited coating film formed on the surface of the magnet test piece, visual observation (n = 10) and film thickness measurement (n = 10) were performed in the same manner as in Example 1. The results are shown in Table 1.

(Peening treatment of vapor deposited aluminum film) Shot peening was performed on the vapor deposited aluminum film formed on the surface of the magnet test piece in the same manner as in Example 1. The aluminum vapor-deposited film subjected to shot peening was subjected to visual observation (n = 10) and film thickness measurement (n = 10) in the same manner as in Example 1. The results are shown in Table 1.

[0025]

[Table 1]

As is clear from Table 1, the amount of gas released from the magnet test piece of Comparative Example 1 was larger than the amount of gas released from the magnet test piece of Example 1. this is,
In Comparative Example 1, the water content and components derived from the used cooling liquid, rust preventive agent, and cleaning liquid could not be sufficiently removed from the surface of the magnet body test piece and remained, which is the result of vaporization. Was inferred. Further, in Comparative Example 1, it took a long time to evacuate when forming the aluminum vapor deposition coating on the surface of the magnet body test piece due to the influence of the components remaining on the surface of the magnet body test piece as described above. Further, in Comparative Example 1, it was not possible to stably form an aluminum vapor-deposited coating as a corrosion-resistant coating having excellent uniformity and adhesion on the surface of the magnet body test piece. On the other hand, in Example 1, the amount of gas released from the magnet test piece was small. It is presumed that this was due to the fact that the water and each component derived from the used cooling liquid, rust preventive agent, and cleaning liquid could be sufficiently removed from the surface of the magnet body test piece during the aging treatment in step 4. Was done. Further, in Example 1, it was possible to stably form an aluminum vapor-deposited coating as a corrosion-resistant coating having excellent uniformity and adhesion on the surface of the magnet body test piece. Although data are not shown, deterioration of magnetic properties was not observed in the magnet body test piece having the aluminum vapor-deposited film subjected to shot peening on the surface thereof in Example 1.

Example 2 (Manufacture of Rare Earth Permanent Magnet) In the same manner as in Example 1, 14
Nd-79Fe-6B-1Co composition (at%) 6 mm
× 15 mm × 30 mm: A magnet test piece having a surface area of 14.4 cm ² was obtained.

(Formation of evaporated aluminum film on the surface of magnet test piece) An aluminum evaporated film was formed on the surface of the magnet test piece in the same manner as in Example 1. In addition, in Example 2, each magnet barrel test piece was attached to each cylindrical barrel of the vapor deposition apparatus.
A total of 1656 magnet test pieces were housed in two cylindrical barrels each having 28 pieces, and vapor deposition processing was performed. With respect to the aluminum vapor-deposited coating film formed on the surface of the magnet test piece, visual observation (n = 10) and film thickness measurement (n = 10) were performed in the same manner as in Example 1. The results are shown in Table 2.

(Peening treatment of vapor-deposited aluminum film) In the same manner as in Example 1, shot peening was performed on the vapor-deposited aluminum film formed on the surface of the magnet test piece. The aluminum vapor-deposited film subjected to shot peening was subjected to visual observation (n = 10) and film thickness measurement (n = 10) in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 2 (Manufacture of Rare Earth Permanent Magnet) A sintered body was obtained in the same manner as in Step 1 in Example 1, and an aging treatment was carried out in the same manner as in Step 4 above. After obtaining the processed body which has been subjected to the aging treatment, washing it in the same manner as in the step 3 and then drying it,
A magnet body test piece having the same composition and dimensions as the magnet body test piece obtained in Example 2 was obtained.

(Formation of evaporated aluminum film on the surface of magnet test piece) An aluminum evaporated film was formed on the surface of the magnet test piece in the same manner as in Example 2. The aluminum vapor-deposited coating formed on the surface of the magnet test piece was subjected to visual observation (n = 10) and film thickness measurement (n = 10) in the same manner as in Example 2. The results are shown in Table 2.

(Peening treatment of vapor deposited aluminum film) Shot peening was performed on the vapor deposited aluminum film formed on the surface of the magnet test piece in the same manner as in Example 2. The aluminum vapor-deposited film subjected to shot peening was subjected to visual observation (n = 10) and film thickness measurement (n = 10) in the same manner as in Example 2. The results are shown in Table 2.

Comparative Example 3 (Manufacture of Rare Earth Permanent Magnet) A sintered body was obtained in the same manner as in Step 1 of Example 1, and was subjected to an aging treatment in the same manner as in Step 4 and in the same manner as in Step 2. An aged processed product was obtained, washed in the same manner as in the same step 3, and then dried. Subsequently, the washed and dried processed body is put into a drum having an opening of a tumbler type blast processing apparatus,
The magnet body test obtained in Example 2 was performed by using Alundum A # 180 (trade name: manufactured by Shinto Blator Co., Ltd., JIS grain size # 180 equivalent) as a shot material, and performing a blasting treatment for 20 minutes while rotating the drum. A magnet test piece having the same composition and dimensions as the piece was obtained. When the cracks of the obtained magnet test pieces were examined, cracks were present at a rate of about 1 in 10.

(Formation of Aluminum Vapor Deposition Coating on Magnet Body Specimen Surface) An aluminum vapor deposition coating was formed on the surface of the magnet body specimen without cracking in the same manner as in Example 2. The aluminum vapor-deposited coating formed on the surface of the magnet test piece was visually observed in the same manner as in Example 2 (n = 1.
0) and film thickness measurement (n = 10). The results are shown in Table 2.

(Peening treatment of vapor-deposited aluminum film) Shot peening was performed on the vapor-deposited aluminum film formed on the surface of the magnet test piece without cracks in the same manner as in Example 2. For the shot-peened aluminum vapor-deposited film, the external appearance was visually observed (n = 10) and the film thickness was measured (n = 10) in the same manner as in Example 2.
I went. The results are shown in Table 2.

[0036]

[Table 2]

As is clear from Table 2, in Example 2, it was possible to stably form an aluminum vapor-deposited coating as a corrosion-resistant coating having excellent uniformity and adhesion on the surface of the magnet body test piece. Although data is not shown, Example 2
No deterioration of the magnetic properties was observed in the magnet body test piece having the aluminum vapor-deposited coating on its surface subjected to the shot peening in the above. In Comparative Example 2, it took a long time to evacuate when forming the aluminum vapor-deposited film on the surface of the magnet body test piece due to the influence of the components remaining on the surface of the magnet body test piece. Further, in Comparative Example 2, it was not possible to stably form an aluminum vapor-deposited coating as a corrosion-resistant coating having excellent uniformity and adhesion on the surface of the magnet test piece. In Comparative Example 3, it was possible to stably form an aluminum vapor-deposited coating as a corrosion-resistant coating having excellent uniformity and adhesion on the surface of the magnet body test piece, but cracking of the magnet body test piece was caused by the blast treatment. I made it.

[0038]

EFFECTS OF THE INVENTION According to the present invention, the residual components on the surface of the processed body are volatilized and / or decomposed and removed by utilizing the high temperature heating for the aging treatment, so that the vapor deposition coating is conventionally formed on the surface. Therefore, the blast treatment for cleaning the surface of the processed body, which was performed as the final step of preparing the rare earth-based permanent magnet, becomes unnecessary. Therefore, it is possible to prevent the occurrence of cracking and chipping of the magnet in the middle of the manufacturing process, and there is no adverse effect on the formation of the vapor deposition coating. Moreover, since high temperature heating is not performed after the aging treatment, deterioration of magnetic characteristics is not caused. Therefore, a vapor-deposited coating as a corrosion-resistant coating having excellent uniformity and adhesion can be stably formed on the surface of the magnet without causing cracking of the magnet or deterioration of the magnetic characteristics during the manufacturing process.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ken Otagaki             1053-45, Mizushima Nishidori, Kurashiki City, Okayama Prefecture             Mizushima Office of Tomo Special Metal Co., Ltd. F-term (reference) 4K018 AA27 CA04 CA11 DA11 DA21                       DA31 FA06 FA08 FA22 FA23                       KA45                 4K029 AA02 BA03 BA17 BA21 BA23                       BC01 BD00 CA01 CA17 DB03                       DB04 DB15 FA04 FA06 JA02                 5E062 CD04 CG05 CG07

Claims (2)

[Claims] 1. A rare earth-based permanent magnet sintered body having a desired composition is subjected to cutting and / or grinding, the obtained processed body is washed and then subjected to an aging treatment, and then to the obtained aging treated body. A method for producing a rare earth-based permanent magnet having a vapor-deposited coating on the surface, which comprises the step of forming a vapor-deposited coating on the surface of the aged body by performing a vapor deposition treatment. 2. The vapor-deposited coating is aluminum, titanium,
The manufacturing method according to claim 1, which is a vapor deposition coating made of an alloy containing aluminum and / or titanium.