JP3423299B2 - Fe-BR type permanent magnet having corrosion-resistant film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Fe-B-R permanent magnet having an excellent corrosion resistant coating. More specifically, it has excellent adhesion to a magnet and has a temperature of 80 ° C and a relative humidity of 90.
% Magnetic properties do not deteriorate even when left for a long time under high temperature and high humidity conditions, and have thermal shock resistance that can withstand a long time heat cycle in a temperature range of -40 ° C to 85 ° C. , Can exhibit stable and high magnetic characteristics,
Furthermore, the present invention relates to an Fe-BR permanent magnet having a corrosion-resistant coating containing no hexavalent chromium on the surface of the magnet.

[0002]

2. Description of the Related Art Fe-BR type permanent magnets represented by Fe-B-Nd type permanent magnets use abundant resources and are cheaper than Sm-Co type permanent magnets. Since it has high magnetic properties, it has been put to practical use in various applications. However, since the Fe-BR permanent magnet contains highly reactive R and Fe, it is easily oxidized and corroded in the atmosphere, and when used without any surface treatment, a slight amount of acid or Corrosion progresses from the surface due to the presence of alkali or moisture, and rust is generated, which causes deterioration or variation in magnet characteristics. Furthermore, when a magnet with rust is incorporated into a device such as a magnetic circuit, the rust may scatter to contaminate peripheral parts.

[0003]

In view of the above points, Fe
In order to improve the corrosion resistance of -BR permanent magnets, there has already been proposed a magnet in which a metal plating film having corrosion resistance is formed on the surface of the magnet by a wet plating method such as an electroless plating method or an electroplating method. (See Japanese Patent Publication No. 3-74012). However, in this method, the acidic solution or alkaline solution used in the pretreatment of the plating treatment remains in the magnet holes, and the magnet may corrode over time. Further, since the magnet has poor chemical resistance, the magnet surface may be corroded during the plating treatment. Furthermore, even if a metal plating film is formed on the magnet surface as described above, the temperature is 60 ° C.
× Corrosion resistance test under the condition of 90% relative humidity
After 00 hours, the magnetic properties may deteriorate by 10% or more from the initial values.

A method of forming an oxidation resistant chemical conversion coating such as a phosphate coating or a chromate coating on the surface of an Fe-BR permanent magnet has also been proposed (Japanese Patent Publication No. 4-2200).
No. 8), the film obtained by this method is excellent in terms of adhesion to the magnet, but at a temperature of 60 ° C. and a relative humidity of 90.
When the corrosion resistance test is conducted under the condition of%, the magnetic characteristics may deteriorate by 10% or more from the initial value after 300 hours.

Further, a method of forming a Al film by a vapor phase growth method, which has been proposed for improving the corrosion resistance of Fe-BR permanent magnets, and then performing a chromate treatment, a so-called aluminum-chromate treatment method ( Japanese Examined Patent Publication (Kokoku) No. 6-66173) significantly improves the corrosion resistance of the magnet. However, since the chromate treatment used in this method uses hexavalent chromium, which is not environmentally desirable, the waste liquid treatment method is complicated, and the film obtained by this method contains hexavalent chromium in a very small amount. There is also concern about the effects on the human body when handling magnets.

On the other hand, in recent years, the Fe-BR permanent magnets have been expected to be applied not only in the electronic industry and the home appliance industry but also in the more severe operating environment. As for the properties required for magnets, not only excellent corrosion resistance under certain conditions but also excellent thermal shock resistance with respect to temperature changes is emphasized. For example, magnets incorporated in parts such as motors for automobiles must be able to withstand large temperature changes, but in order to meet this demand, the corrosion-resistant film itself formed on the magnets also has to undergo temperature changes. Must not cause cracking or peeling.

Therefore, in the present invention, the adhesiveness with the magnet is excellent, the magnetic characteristics are not deteriorated even when left for a long time under a high temperature and high humidity condition of a temperature of 80 ° C. and a relative humidity of 90%. It has a thermal shock resistance that can withstand a long-term heat cycle in a temperature range of 40 ° C to 85 ° C, can exhibit stable and high magnetic properties, and has corrosion resistance that does not contain hexavalent chromium in the film. It is an object of the present invention to provide an Fe-BR type permanent magnet having a coating on the surface of a magnet.

[0008]

Means for Solving the Problems In the course of conducting various studies in view of the above points, the present inventors have made Fe-BR
We focused on forming a metal film on the surface of the system permanent magnet and then forming a metal oxide film on it that has little effect on the human body and the environment. The method itself of forming an underlayer containing a metal as a main component on the surface of the Fe-BR permanent magnet and forming a glass layer on the surface of the underlayer has already been proposed (Japanese Patent Laid-Open No. 1-165105). (See the official gazette). JP-A-1-16510
According to Japanese Unexamined Patent Publication No. 5 (1994), it is difficult to form a uniform film when the thickness of the glass layer is less than 1 μm. However, as a result of further investigations by the present inventors, surprisingly, a metal film was formed on the surface of the Fe—B—R permanent magnet, and in consideration of the components of the metal film, the film thickness was 1 μm or less. When a specific metal oxide film having a film thickness is formed, the metal oxide film firmly adheres to the magnet and is excellent not only in corrosion resistance under certain conditions but also in thermal shock resistance against temperature change. It was found that the effect was exhibited.

The present invention has been made on the basis of such findings, and the permanent magnet of the present invention has a structure as described in claim 1.
-The thickness of the B-R permanent magnet is 0.
It has a metal oxide film of 05 μm to 0.5 μm, and the metal oxide film is composed of a metal oxide component containing the same metal component as the metal component of the metal film. Further, the permanent magnet according to claim 2 is the permanent magnet according to claim 1, wherein the metal coating is Al, Sn, Zn, Cu, F.
It is characterized by comprising at least one metal component selected from e, Ni, Co and Ti. A permanent magnet according to a third aspect is the permanent magnet according to the first aspect, characterized in that the film thickness of the metal coating is 0.01 μm to 50 μm. A permanent magnet according to a fourth aspect is the permanent magnet according to the first aspect, wherein the metal oxide film is an Al oxide,
It is characterized by comprising at least one metal oxide component selected from Si oxide, Zr oxide, and Ti oxide.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, examples of the metal component of the metal coating formed on the surface of the Fe-BR system permanent magnet include Al, Sn, Zn, Cu, Fe, Ni,
At least one selected from Co and Ti can be mentioned.

The method for forming the metal coating is not particularly limited, but it is preferable to use the vapor phase growth method in consideration of the fact that the magnet and the metal coating are easily oxidized and corroded.
Examples of the vapor phase growth method include known methods such as a vacuum vapor deposition method, an ion sputtering method, and an ion plating method. The metal film may be formed under general conditions in each method. It is desirable to use the vacuum deposition method or the ion plating method from the viewpoints of the denseness of the metal film, the uniformity of the film thickness, the film formation rate, and the like. Needless to say, the magnet surface may be subjected to known cleaning treatments such as cleaning, degreasing, and sputtering before the film formation. The temperature of the magnet when forming the metal film is preferably set to 200 ° C to 500 ° C. 200
If the temperature is lower than 0 ° C, a film having excellent adhesion to the magnet surface may not be formed, and if it exceeds 500 ° C, cracks may occur in the film during the cooling process after film formation, and the film may peel off from the magnet. Because there is.

If the thickness of the metal coating formed by the above method is less than 0.01 μm, excellent corrosion resistance may not be exhibited, and if it exceeds 50 μm, not only the production cost may increase, but also Since the effective volume of the magnet may be small, 0.01 μm to 50 μm
Is preferable, and 0.05 μm to 25 μm is more preferable.

It is also possible to increase the adhesion between the magnet surface and the metal film by heat treating after forming the metal film on the magnet surface by the above method. The heat treatment may be performed at this stage, but the same effect can be obtained by the heat treatment for forming a metal oxide film described later. If the temperature of the heat treatment exceeds 500 ° C., the magnetic properties of the magnet may be deteriorated and the metal film may be melted. Therefore, it is desirable to perform the heat treatment at 500 ° C. or less.

The method for forming the metal oxide film is not particularly limited, but a sol solution obtained by a hydrolysis reaction and a polymerization reaction of a metal compound as a raw material of the metal oxide film is applied and heat treated. The sol-gel film forming method for forming the metal oxide film is desirable in that the metal oxide film can be formed easily and safely.

The metal oxide film comprises a metal oxide component containing the same metal component as the metal component of the metal film formed on the surface of the metal oxide film. The metal oxide film may be a film made of a single metal oxide component or a composite film made of a plurality of metal oxide components. Examples of the metal oxide component include Al oxide, Si oxide,
At least one metal oxide component selected from Zr oxide and Ti oxide can be mentioned.

Among the coatings composed of a single metal oxide component, the Si oxide coating (SiO _x coating: 0 <x ≦ 2) is
The sol liquid for forming the film is more stable than the sol liquid for forming the other metal oxide film, and it is formed at a lower temperature than the case of forming the film containing other metal oxide components. Therefore, it is advantageous in that the influence on the magnetic characteristics of the magnet can be reduced. The Zr oxide coating (ZrO _x coating: 0 <x ≦ 2) is advantageous in that it is excellent in alkali resistance as well as corrosion resistance. By forming a metal oxide film containing the same metal component as the metal component of the metal film to be the underlayer (for example, an Al oxide film (Al ₂ O _x film: 0 <x ≦ 3) is formed on the Al film). When formed), the adhesion at the interface between the metal film and the metal oxide film can be made stronger. As a composite film composed of a plurality of metal oxide components, Si-A
l Complex oxide film (SiO _x Al ₂ O _y film: 0 <x
≦ 2.0 <y ≦ 3) and Si-Zr composite oxide film (S
iO _x · ZrO _y film: 0 <x ≦ 2 · 0 <y ≦ 2),
Si-Ti composite oxide film (SiO _x TiO _y film:
0 <x ≦ 2 · 0 <y ≦ 2) and the like. The composite film containing the Si oxide component is advantageous in that the sol liquid is relatively stable and that it can be formed at a relatively low temperature, so that the influence on the magnetic characteristics of the magnet can be reduced. The composite film containing the Zr oxide component is advantageous in that it is also excellent in alkali resistance. By forming a composite film containing the same metal component as the metal component of the underlying metal film (for example, when a Si-Al composite oxide film is formed on the Al film or Si-Ti is formed on the Ti film).
When a composite oxide film is formed), the adhesion at the interface between the metal film and the composite film can be made stronger.

The sol solution used in the sol-gel film forming method is prepared by adjusting a metal compound, which is a constituent source of the metal oxide film, a catalyst, a stabilizer, water, etc., in an organic solvent to carry out a hydrolysis reaction or a metal compound. It is a solution in which a colloid obtained by a polymerization reaction or the like is dispersed.

Examples of the metal compound as a constituent source of the metal oxide film include metal alkoxides such as methoxide, ethoxide, propoxide, butoxide (some alkoxyl groups are alkyl groups such as methyl groups and ethyl groups, phenyl groups, etc.). Carboxylic acid salts such as metal oxalates, acetates, octylates, stearates, chelate compounds of metals with acetylacetonate, and metal nitrates. Inorganic salts typified by chlorides and chlorides can be used. Considering the stability and cost of the sol solution, for example, in the case of an Al compound used when forming an Al oxide film or a Zr compound used when forming a Zr oxide film, propoxy of Al or Zr is used. It is desirable to use an alkoxide having an alkoxyl group having 3 to 4 carbon atoms such as a metal or butoxide, or a carboxylate such as a metal acetate or octylate. In the case of the Si compound used for forming the Si oxide film, it is desirable to use an alkoxide having an alkoxy group having 1 to 3 carbon atoms such as Si methoxide, ethoxide, and propoxide. In the case of a Ti compound used for forming a Ti oxide film, Ti has a carbon number of 2 to 4 such as ethoxide, propoxide and butoxide.
It is desirable to use an alkoxide having an alkoxyl group.

When forming the composite oxide film, a plurality of
Metal compounds can be mixed and used, or metal composites
Metal complex compounds such as alkoxides alone
It can also be used as a mixture with a genus compound. For example, S
When forming the i-Al composite oxide film, Si-O-
Alkoxyl groups having 1 to 4 carbon atoms and having an Al bond (one
Part of the alkoxyl group is an alkyl group such as methyl group or ethyl group.
May be substituted with a phenyl group or a phenyl group.
Si-, such as a Si-Al composite alkoxide having
An Al composite compound can be used. Compound like this
Specifically, (H_ThreeCO)_Three-Si-O-
Al- (OCH_Three)_TwoOr (H₅C_TwoO) _Three-Si-O
-Al- (OC_TwoH₅)_TwoAnd so on.

When forming a composite oxide film using a plurality of metal compounds, the mixing ratio of each metal compound is not particularly limited, and may be determined according to the desired component ratio of the composite oxide film. . For example, when forming a Si-Al composite oxide film on an Al film, Si
The number of moles of Al (Al / Si + Al) relative to the total number of moles of Si and Al contained in the -Al composite oxide film is 0.
Si compound and Al so that 001 or more (molar ratio)
It is desirable to use a mixture of compounds or a mixture of a Si compound and a Si-Al composite compound. By using such a mixing ratio, excellent properties of the Si oxide film (the sol liquid is relatively stable,
It is possible to improve the reactivity at the interface with the Al film while maintaining that the film can be formed at a relatively low temperature. In addition, when the heat treatment after coating the sol liquid on the surface of the metal film is performed at 150 ° C. or less, the above molar ratio is preferably 0.5 or less, and when performed at 100 ° C. or less, the above molar ratio is used. Is preferably 0.2 or less. This is because it is necessary to raise the heat treatment temperature as the mixing ratio of Al increases.

The mixing ratio of the metal compound to the sol liquid is
0.1 wt% to 20 wt% (converted to metal oxide (for example, in the case of Si compound, converted to SiO ₂ , Si compound + A
In the case of the 1 compound, the range of (SiO ₂ + Al ₂ O ₃ conversion)) is desirable. This is because if the blending ratio is less than 0.1 wt%, an excessive number of film forming steps may be required to obtain a film having a sufficient film thickness. Further, if it exceeds 20 wt%, the viscosity of the sol liquid becomes high, which may make it difficult to form a film.

As the catalyst, acids such as acetic acid, nitric acid and hydrochloric acid can be used alone or in combination. The proper addition amount is defined by the hydrogen ion concentration of the sol solution to be prepared, and it is desirable to add it so that the sol solution has a pH of 2-5. This is because if the pH is less than 2 or more than 5, there is a possibility that the hydrolysis reaction, the polymerization reaction, etc. at the time of preparing a sol solution suitable for film formation may not be controlled.

The stabilizer used as necessary for stabilizing the sol liquid is appropriately selected according to the chemical stability of the metal compound used, and β including acetylacetone is used. Compounds that form chelates with metals, such as diketones and β-keto acid esters such as ethyl acetoacetate, are desirable. The blending amount of the stabilizer is preferably 2 or less in terms of molar ratio (stabilizer / metal compound) when using β-diketone. This is because if the molar ratio exceeds 2, there is a possibility that the hydrolysis reaction or the polymerization reaction during the preparation of the sol solution may be hindered.

The water contained in the sol liquid may be supplied directly, but for example, a chemical reaction such as the use of water produced by the esterification reaction with a carboxylic acid when alcohol is used as a solvent. The method may be an indirect supply using, or a method of utilizing water vapor in the atmosphere. When water is directly or indirectly supplied to the sol liquid, the water / metal compound molar ratio is preferably 100 or less. This is because if the molar ratio exceeds 100, the stability of the sol liquid may be affected.

The organic solvent is not limited as long as it can uniformly dissolve the metal compound, the catalyst, the stabilizer and the water, which are the components of the sol liquid, and uniformly disperse the obtained colloid. , For example, lower alcohols typified by ethanol, hydrocarbon ether alcohols typified by ethylene glycol monoalkyl ether, acetic acid esters of hydrocarbon ether alcohol typified by ethylene glycol monoalkyl ether acetate, and lower typified by ethyl acetate. Although acetic acid esters of alcohols, ketones represented by acetone, etc. can be used, it is preferable to use lower alcohols such as ethanol, isopropyl alcohol, butanol alone or in combination from the viewpoint of safety during processing and cost. .

Although the viscosity of the sol liquid depends on the combination of various components contained in the sol liquid, it is generally desirable that the viscosity is less than 20 cP. This is because if it exceeds 20 cP, it becomes difficult to form a uniform film, and cracks may occur during heat treatment.

The adjusting time and adjusting temperature of the sol solution depend on the combination of various components contained in the sol solution.
Adjusting time is 1 minute to 72 hours, adjusting temperature is 0 ℃ to 100 ℃
Is.

As a method of applying the sol liquid to the surface of the metal film, a dip coating method, a spray method, a spin coating method or the like can be used.

After applying the sol liquid to the surface of the metal film, heat treatment is performed. The temperature of the treatment needs to be at least a temperature at which the organic solvent is evaporated. For example, when ethanol is used as the organic solvent, its boiling point is 80 ° C.
is necessary. On the other hand, in the case of a sintered magnet, the heat treatment temperature is 5
If the temperature exceeds 00 ° C, the magnetic properties of the magnet may be deteriorated and the metal film may be dissolved. Therefore, the heat treatment temperature is preferably 80 ° C to 500 ° C, but more preferably 80 ° C to 250 ° C from the viewpoint of preventing the occurrence of cracks during cooling after the heat treatment as much as possible. In the case of a bonded magnet, the temperature condition for heat treatment must be set in consideration of the heat resistant temperature of the resin used. For example, in the case of a bonded magnet using an epoxy resin or a polyamide resin, the heat treatment temperature is preferably 80 ° C to 200 ° C in consideration of the heat resistant temperature of these resins.
The heat treatment time is usually 1 minute to 1 hour.

According to the above method, it is possible to obtain a metal oxide film mainly composed of amorphous material having excellent corrosion resistance. Note that, for example, in the case of a Si-Al composite oxide film, the structure is Si-O-Si in the case of a film rich in Si component.
Bonds and Si-O-Al bonds are abundant, and when the Al component is abundant, Al-O-Al bonds and Si-O-Al bonds are abundant. The existence ratio of both components in the film is determined by the mixing ratio of the above metal compounds.

Further, according to the above method, the metal oxide film contains C derived from the metal compound and the stabilizer. C
By containing, it becomes easy to obtain a metal oxide film mainly composed of an amorphous material having excellent corrosion resistance, but its content is preferably 50 ppm to 1000 ppm (wt / wt). If the C content is less than 50 ppm, cracks may form in the film, and the C content is 1000 pp.
This is because if it exceeds m, the film may not be sufficiently densified.

If the film thickness of the metal oxide film formed by the above method is less than 0.01 μm, it may not be possible to exhibit excellent corrosion resistance under certain conditions, and if the film thickness exceeds 1 μm, it may change due to temperature changes. There is a possibility that cracks and peeling may occur and excellent thermal shock resistance may not be exhibited . To both excellent thermal shock resistance for excellent corrosion resistance and temperature variation in certain conditions, the film thickness of the metal oxide coating to 0.05Myuemu～0.5Myuemu.
In addition, if necessary, application of a sol solution to the surface of the metal film,
It goes without saying that the subsequent heat treatment may be repeated a plurality of times.

Forming a metal oxide film on the metal film
As a pre-process, shot peening (impacting hard particles
The surface may be modified by
Yes. Metal film by shot peening
Metal acid that smoothes the surface and has excellent corrosion resistance even in thin films
The compound film can be easily formed. Shot pie
As the powder used for hardening, the hardened metal film formed
It is desirable that the hardness is equal to or higher than the degree.
Mohs hardness like 3 balls and glass beads is 3
The above spherical hard powders can be mentioned. The average particle size of the powder is
If the thickness is less than 30 μm, the pressing force against the metal film is small and
It takes time to reason. On the other hand, if it exceeds 3000 μm, the surface
Roughness may become too rough and the finished surface may be uneven
There is. Therefore, the average particle size of the powder is 30 μm to 3 μm.
000 μm is preferable, and 40 μm to 2000 μm is more preferable.
desirable. Injection pressure in shot peening is 1.0
kg / cm^Two~ 5.0 kg / cm ^TwoIs desirable. Injection pressure
Is 1.0 kg / cm^TwoIf less than, pressing force against the metal film
Is small and processing takes time, and the injection pressure is 5.0 kg / c
m^TwoIf the pressure exceeds the value, the pressing force against the metal film will become uneven.
The surface roughness may deteriorate. Sho
Injecting time in peening is 1 minute to 1 hour
Good If the injection time is less than 1 minute, a uniform treatment will be performed on all surfaces.
It may not be possible to make sense, and if it exceeds 1 hour, the surface roughness
This may lead to deterioration of

The rare earth element (R) in the Fe-BR permanent magnet used in the present invention is Nd, Pr or D.
At least one of y, Ho, Tb, Sm, or further La, Ce, Gd, Er, Eu, Tm, Yb,
A material containing at least one of Lu and Y is desirable.
Usually, one of R is sufficient, but in practice, a mixture of two or more kinds (Misch metal, didymium, etc.) can be used for reasons of availability. F
The content of R in the e-B-R permanent magnet is 10 atom%.
If less than 30%, the crystal structure becomes a cubic structure having the same structure as α-Fe, so that high magnetic properties, particularly high coercive force (iHc), cannot be obtained. Since the residual magnetic flux density (Br) decreases and a permanent magnet with excellent characteristics cannot be obtained, the R content is 1 of the composition.
It is desirable that the content is 0 atom% to 30 atom%.

When the Fe content is less than 65 atomic%, Br decreases, and when it exceeds 80 atomic%, a high iHc cannot be obtained. Therefore, the Fe content is preferably from 65 atomic% to 80 atomic%. Further, by substituting a part of Fe with Co, the temperature characteristics can be improved without impairing the magnetic characteristics of the obtained magnet. However, when the Co substitution amount exceeds 20% of Fe, the magnetic characteristics are improved. It is not desirable because it deteriorates. When the Co substitution amount is 5 atom% to 15 atom%, Br increases as compared with the case where no substitution is performed, and therefore it is desirable to obtain a high magnetic flux density.

When the content of B is less than 2 atomic%, the rhombohedral structure becomes the main phase and a high iHc cannot be obtained, and when it exceeds 28 atomic%, the B-rich non-magnetic phase increases and Br decreases, which is excellent. 2% by atom to 2
The content of 8 atomic% is desirable. Also, in order to improve the manufacturability of magnets and reduce the price, P of 2.0 wt% or less, 2.0 w
At least one of S of t% or less, and the total amount is 2.0.
You may contain the wt% or less. Furthermore, the corrosion resistance of the magnet can be improved by substituting 30% by weight or less of C for B.

Further, Al, Ti, V, Cr, Mn, B
i, Nb, Ta, Mo, W, Sb, Ge, Sn, Zr,
The addition of at least one of Ni, Si, Zn, Hf, and Ga is effective in improving the squareness of the coercive force and demagnetization curve, improving the manufacturability, and reducing the cost. In addition, in order to set the maximum energy product (BH) max to 20 MGOe or more, Br needs to be at least 9 kG or more. The Fe-B-R permanent magnet may contain impurities unavoidable in industrial production in addition to R, Fe, and B.

Fe-B used in the present invention
The -R permanent magnet has a compound having a tetragonal crystal structure having an average crystal grain size in the range of 1 μm to 80 μm as a main phase, and a volume ratio of 1% to 50% of a non-magnetic phase (oxide phase). Except) is included. The magnet has iHc ≧ 1k
Oe, Br> 4 kG, (BH) max ≧ 10 MGOe, and the maximum value of (BH) max reaches 25 MGOe or more.

Further, another film may be laminated on the metal oxide film of the present invention. By adopting such a configuration, it is possible to enhance / complement the characteristics of the metal oxide film or to add further functionality.

[0040]

EXAMPLES For example, as described in US Pat. No. 4,770,723, 17Nd-1Pr obtained by pulverizing a known casting ingot and performing fine pulverization, molding, sintering, heat treatment, and surface treatment. -75Fe-7
The following experiment was conducted using a sintered magnet having a B composition of 23 mm × 10 mm × 6 mm (hereinafter referred to as “magnet test piece”). In the following experiments, the film thickness of the metal film was measured using a fluorescent X-ray film thickness meter. The film thickness of the metal oxide film was measured by observing the fracture surface with an electron microscope. The amount of C in the metal oxide film was measured using a glow discharge mass spectrometer. The structure of the metal oxide film was analyzed using an X-ray diffractometer. The present invention is not limited to the application to the Fe-BR system sintered magnet, but can also be applied to the Fe-B-R system bonded magnet.

Experimental Example 1: The magnet test piece was evacuated to 1 × 10 ⁻⁴ Pa or less in the vacuum chamber, and the Ar gas pressure was set to 1
0 Pa, bias voltage -400V, 35 minutes,
The magnet surface was cleaned by sputtering. Ar gas pressure 0.2 Pa, bias voltage -50 V, magnet temperature 250
At the temperature of ℃, using metal Al as a target, arc ion plating was performed for 10 minutes,
1 film was formed and allowed to cool. The thickness of the obtained Al coating was 0.5 μm. The sol solution was added with the Al compound, catalyst, stabilizer, organic solvent and water components shown in Table 1,
The composition, the viscosity and the pH shown in Table 2 were adjusted, and the dip coating method was applied to the magnet having the Al film at the pulling rate shown in Table 3 and heat-treated to form an Al oxide film on the Al film. did. Obtained film (Al ₂ O _x
Film: The film thickness of 0 <x ≦ 3) was 0.3 μm. The amount of C in the film was 350 ppm. The structure of the film was amorphous. A magnet having an Al oxide film was obtained on the surface of the magnet through the Al film by the method described above at a temperature of 80.
The sample was left for 300 hours under a high temperature and high humidity condition of ° C x 90% relative humidity to perform an accelerated corrosion resistance test. Table 4 shows the magnetic properties before and after the test and the appearance changes after the test. As a result, the obtained magnet has almost no deterioration in magnetic properties and appearance even when left for a long time under high temperature and high humidity conditions.
It was found that the required corrosion resistance was sufficiently satisfied.

Experimental Example 2: Magnet body test under the same conditions as Experimental Example 1.
After cleaning the test piece, Ar gas pressure 1Pa, voltage 1.5kV
Al wire is used as coating material under
I, Al wire is heated to evaporate, ionize, 1
Minute, using an ion plating method, Al skin on the magnet surface
A film was formed and allowed to cool. The thickness of the obtained Al film was 0.
It was 9 μm. The sol solution was treated with Al compounds shown in Table 1
See Table 2 for media, stabilizers, organic solvents and water components.
Adjust with the composition, viscosity and pH shown, and use dip coat
With Al film at the pulling rate shown in Table 3
Applied to the magnet and heat treated to form an Al acid film on the Al film.
A compound film was formed. The obtained Al oxide film (Al_Two
O _xFilm: The film thickness of 0 <x ≦ 3) was 0.1 μm.
The amount of C in the film was 120 ppm. The structure of the film is
Some of them are crystalline, but the main one is amorphous.
It was An Al coating is formed on the surface of the magnet obtained by the above method.
Then, for a magnet having an Al oxide film, Experimental Example 1
An accelerated corrosion resistance test was conducted under the same conditions as above. The results are shown in Table 4.
Shown in. As a result, the resulting magnet has the required corrosion resistance.
It turned out that he was fully satisfied with his sex. Also another real
As a test, modified acrylate adhesive (product number
Drock G-55: manufactured by Denki Kagaku Kogyo Co., Ltd.
Bonded magnet to a cast iron jig and leave it for 24 hours before
A compression shear test was performed using a Mussler tester and the resulting magnetic
When the shear adhesive strength of the stone was measured, it was 341 kg weight /
cm^TwoIt showed an excellent value.

Experimental Example 3: After cleaning a magnet body test piece under the same conditions as in Experimental Example 1, arc ion plating was performed for 2.5 hours to form an Al film on the magnet surface and allowed to cool. The film thickness of the obtained Al film was 5 μm. The sol solution was added with the Al compound, the catalyst, the stabilizer, the organic solvent, and the water components shown in Table 1, and the composition, viscosity, and p shown in Table 2 were obtained.
After adjusting with H, it was applied to a magnet having an Al film at a pulling rate shown in Table 3 by a dip coating method, and heat-treated to form an Al oxide film on the Al film. The film thickness of the obtained film (Al ₂ O _x film: 0 <x ≦ 3) was 0.3 μm. The amount of C in the film was 350 ppm. The structure of the film was amorphous. Acceleration of corrosion resistance is obtained by leaving the magnet obtained by the above method and having an Al oxide film on the surface of the magnet through the Al film under high temperature and high humidity conditions of temperature 80 ° C. and relative humidity 90% for 1000 hours. The test was conducted. Table 5 shows the magnetic properties before and after the test and the appearance change state after the test. As a result, it was found that the obtained magnet was sufficiently satisfied with the required corrosion resistance without being deteriorated in magnetic properties and appearance even when left for a long time under high temperature and high humidity conditions.

Experimental Example 4: 7 minutes under the same conditions as in Experimental Example 2,
An Al coating was formed on the surface of the magnet by the ion plating method and allowed to cool. The film thickness of the obtained Al film was 7 μm. Then, a spherical glass bead powder having an average particle diameter of 120 μm and a Mohs hardness of 6 was sprayed onto the surface of the Al coating at a spraying pressure of 1.5 kg / cm ^{2 for} 5 minutes together with a pressurized gas of N ₂ gas, Shot peened.
The sol solution was adjusted with the Al compound, the catalyst, the stabilizer, the organic solvent and the water components shown in Table 1 to the composition, viscosity and pH shown in Table 2.
Apply to the magnet with Al coating at the pulling speed shown in
Heat treatment was performed to form an Al oxide film on the Al film. The film thickness of the obtained film (Al ₂ O _x film: 0 <x ≦ 3) was 0.1 μm. The amount of C in the film is 120ppm
Met. The structure of the film was amorphous. A corrosion resistance acceleration test under the same conditions as in Experimental Example 3 was performed on the magnet obtained by the above method and having an Al oxide film on the magnet surface via the Al film. The results are shown in Table 5. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance. In addition, as another experiment, a compression shear test under the same conditions as in Experimental Example 2 was performed, and the shear adhesive strength of the obtained magnet was measured.
^It showed an excellent value of ² .

Experimental Example 5: An Al film was formed on the surface of the magnet by the ion plating method under the same conditions as in Experimental Example 10 for 10 minutes, and then allowed to cool. The thickness of the obtained Al film is 10μ
It was m. The sol solution was prepared from the Al compound, catalyst, and
The composition, the viscosity and the pH shown in Table 2 were adjusted with each component of the stabilizer, the organic solvent and water, and the dip coating method was applied to the magnet having an Al film at the pulling rate shown in Table 3 and heat treatment was performed. Then, an Al oxide film was formed on the Al film. Obtained film (Al ₂ O _x film: 0 <
The film thickness of x ≦ 3) was 1 μm. The amount of C in the film is 50
It was 0 ppm. The structure of the film was amorphous. On the surface of the magnet obtained by the above method, through the Al film, A
A corrosion resistance acceleration test under the same conditions as in Experimental Example 3 was performed on the magnet having the 1-oxide film. The results are shown in Table 5.
As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

[Table 5]

Comparative Example 1: After degreasing and pickling a magnet test piece,
It was dipped in a treatment liquid containing zinc 4.6 g / l and phosphate 17.8 g / l at a bath temperature of 70 ° C. to form a phosphate film having a film thickness of 1 μm on the magnet surface. The obtained magnet was subjected to an accelerated corrosion resistance test under the same conditions as in Experimental Example 1. The results are shown in Table 4. As a result, the obtained magnet caused deterioration of magnetic properties and rusting.

Comparative Example 2: A magnet test piece was subjected to an accelerated corrosion resistance test under the same conditions as in Experimental Example 1. The results are shown in Table 4. As a result, the magnet test piece caused deterioration of magnetic properties and rusting.

Comparative Example 3: A magnet having an Al coating on the surface of the magnet which was shot peened in Experimental Example 4 was subjected to an accelerated corrosion resistance test under the same conditions as in Experimental Example 3. The results are shown in Table 5. As a result, the obtained magnet caused deterioration of magnetic properties and rusting.

Comparative Example 4 After cleaning the magnet having the Al coating on the surface of the magnet which was shot peened in Experimental Example 4, 300 g / l of sodium hydroxide and 40 g / zinc oxide were used.
1, the ferric chloride 1 g / l, Rochelle salt 30 g / l, and a bath temperature of 23 ° C. were immersed in the treatment liquid to replace the Al film surface with Zn. Furthermore, nickel sulfate 240 g / l, nickel chloride 48 g / l, nickel carbonate suitable amount (pH adjustment), boric acid 3
Electroplating was performed at a current density of 1.8 A / dm ² using a plating solution having a bath temperature of 55 ° C. and a pH of 4.2 consisting of 0 g / l, and a film thickness was formed on the Al film whose surface was replaced by Zn. Formed a Ni film of 0.9 μm. The obtained magnet was subjected to an accelerated corrosion resistance test under the same conditions as in Experimental Example 3. The results are shown in Table 5. As a result, in the obtained magnet, the magnetic characteristics were deteriorated, and a part of the Ni coating was peeled off.

Experimental Example 6: For the magnet obtained in Experimental Example 1 having an Al coating of 0.5 μm on the magnet surface, the Si compound, Al compound, catalyst, stabilizer, organic solvent and water shown in Table 6 were used. For each of the components, the composition, viscosity and p shown in Table 7
A sol liquid of H was prepared, and was applied by a dip coating method at a pulling rate shown in Table 8 and heat-treated to form a Si-Al composite oxide film on the Al film. The obtained film (SiO _x Al ₂ O _y film: 0 <x ≦ 2.0 <
Table 9 shows the film thickness of y ≦ 3), the amount of C in the film, and the structure of the film. The corrosion resistance accelerated test under the same conditions as in Experimental Example 1 was performed on the magnet obtained by the above method and having the Si-Al composite oxide film on the magnet surface via the Al film. The results are shown in Table 10. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance. As another experiment, a compression shear test under the same conditions as in Experimental Example 2 was performed, and the shear adhesive strength of the obtained magnet was measured. As a result, an excellent value of 322 kgf / cm ² was shown.

Experimental Example 7: For the magnet having an Al coating of 0.9 μm on the magnet surface obtained in Experimental Example 2, the Si compound, Al compound, catalyst, stabilizer, organic solvent and water shown in Table 6 were used. For each of the components, the composition, viscosity and p shown in Table 7
A sol liquid of H was prepared, and was applied by a dip coating method at a pulling rate shown in Table 8 and heat-treated to form a Si-Al composite oxide film on the Al film. The obtained film (SiO _x Al ₂ O _y film: 0 <x ≦ 2.0 <
Table 9 shows the film thickness of y ≦ 3), the amount of C in the film, and the structure of the film. The corrosion resistance accelerated test under the same conditions as in Experimental Example 1 was performed on the magnet obtained by the above method and having the Si-Al composite oxide film on the magnet surface via the Al film. The results are shown in Table 10. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance. As another experiment, a compression shear test under the same conditions as in Experimental Example 2 was performed, and the shear adhesive strength of the obtained magnet was measured. As a result, an excellent value of 332 kgf / cm ² was shown.

Experimental Example 8: For the magnet obtained in Experimental Example 3 and having a 5 μm Al coating on the magnet surface, S shown in Table 6 was used.
The sol liquid having the composition, viscosity and pH shown in Table 7 was adjusted with each component of i compound, Al compound, catalyst, stabilizer, organic solvent and water, and the pulling rate shown in Table 8 was obtained by the dip coating method. And applied a heat treatment to form a Si-Al composite oxide film on the Al film. Obtained film (SiO _x Al ₂ O _y film: 0 <x ≦ 2.0 <y ≦
Table 9 shows the film thickness of 3), the amount of C in the film, and the structure of the film. The corrosion resistance accelerated test under the same conditions as in Experimental Example 3 was performed on the magnet obtained by the above method and having the Si-Al composite oxide film on the magnet surface via the Al film. The results are shown in Table 11. As a result, the resulting magnet is
It was found that the required corrosion resistance was sufficiently satisfied. As another experiment, a compression shear test under the same conditions as in Experimental Example 2 was performed, and the shear adhesive strength of the obtained magnet was measured. As a result, an excellent value of 322 kgf / cm ² was shown.

Experimental Example 9: For the magnet obtained in Experimental Example 4 having an Al coating of 7 μm on the magnet surface, S shown in Table 6 was used.
The sol liquid having the composition, viscosity and pH shown in Table 7 was adjusted with each component of i compound, Al compound, catalyst, stabilizer, organic solvent and water, and the pulling rate shown in Table 8 was obtained by the dip coating method. And applied a heat treatment to form a Si-Al composite oxide film on the Al film. Obtained film (SiO _x Al ₂ O _y film: 0 <x ≦ 2.0 <y ≦
Table 9 shows the film thickness of 3), the amount of C in the film, and the structure of the film. An accelerated corrosion resistance test under the same conditions as in Experimental Example 3 was performed on the magnet obtained by the above method and having the Si-Al composite oxide film on the magnet surface via the Al film. The results are shown in Table 11. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance.
As another experiment, a compression shear test under the same conditions as in Experimental Example 2 was performed, and the shear adhesive strength of the obtained magnet was measured. As a result, an excellent value of 319 kgf / cm ² was shown.

Experimental Example 10: Each of the Si compounds, Al compounds, catalysts, stabilizers, organic solvents and water shown in Table 6 was applied to the magnet having an Al coating of 10 μm on the surface of the magnet obtained in Experimental Example 5. In composition, composition, viscosity and p shown in Table 7
A sol liquid of H was prepared, and was applied by a dip coating method at a pulling rate shown in Table 8 and heat-treated to form a Si-Al composite oxide film on the Al film. The obtained film (SiO _x Al ₂ O _y film: 0 <x ≦ 2.0 <
Table 9 shows the film thickness of y ≦ 3), the amount of C in the film, and the structure of the film. The corrosion resistance accelerated test under the same conditions as in Experimental Example 3 was performed on the magnet obtained by the above method and having the Si-Al composite oxide film on the magnet surface via the Al film. The results are shown in Table 11. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance. As another experiment, a compression shear test under the same conditions as in Experimental Example 2 was performed, and the shear adhesive strength of the obtained magnet was measured. As a result, an excellent value of 329 kgf / cm ² was shown.

[0060]

[Table 6]

[0061]

[Table 7]

[0062]

[Table 8]

[0063]

[Table 9]

[0064]

[Table 10]

[0065]

[Table 11]

Experimental Example 11: After cleaning a magnet test piece under the same conditions as in Experimental Example 1, metal Ti was used as a target under the conditions of Ar gas pressure of 0.1 Pa, bias voltage of −80 V and magnet temperature of 400 ° C. Arc ion plating was performed for 3 hours to form a Ti film on the surface of the magnet, which was allowed to cool. The thickness of the obtained Ti film was 5 μm. The sol solution was adjusted with the Ti compound, catalyst, stabilizer, organic solvent and water components shown in Table 12 to have the composition, viscosity and pH shown in Table 13, and was prepared by the dip coating method.
Apply to the magnet with Ti coating at the pulling speed shown in
Heat treatment was performed to form a Ti oxide film on the Ti film. The film thickness of the obtained film (TiO ₂ film: 0 <x ≦ 2) was 0.1 μm. The amount of C in the film was 140 ppm. The structure of the film was amorphous. The corrosion resistance acceleration test under the same conditions as in Experimental Example 3 was performed on the magnet having the Ti oxide film on the magnet surface through the Ti film obtained by the above method. The results are shown in Table 15. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance.

[0067]

[Table 12]

[0068]

[Table 13]

[0069]

[Table 14]

[0070]

[Table 15]

[0071]

The Fe-BR permanent magnet of the present invention has a metal oxide film having a thickness of 0.01 μm to 1 μm on the surface of the Fe-BR permanent magnet, and the metal oxide film is the metal film. The permanent magnet composed of the metal oxide component containing the same metal component as the above metal component has a temperature of 80 ° C. ×
Even when left for a long time under a high temperature and high humidity condition with a relative humidity of 90%, the magnetic properties and the appearance hardly deteriorate. Further, it has excellent thermal shock resistance capable of withstanding a long-time heat cycle in a temperature range of -40 ° C to 85 ° C.

─────────────────────────────────────────────────── ─── Continuation of front page (31) Priority claim number Japanese Patent Application No. 10-303731 (32) Priority date October 26, 1998 (October 26, 1998) (33) Country of priority claim Japan (JP) (31) Priority claim number Japanese Patent Application No. 10-349915 (32) Priority date December 9, 1998 (December 9, 1998) (33) Country of priority claim Japan (JP) (56) References Japanese Patent Laid-Open No. 4-328804 (JP, A) Japanese Patent Laid-Open No. 6-318512 (JP, A) Japanese Patent Laid-Open No. 9-326308 (JP, A) Japanese Patent Laid-Open No. 7-74043 (JP, A) Japanese Patent Laid-Open No. 6-176911 (JP , A) United States Patent 5089066 (US, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01F 1/00-1/117 H01F 41/00-41/04 H01F 41/08-41 / 10 C22C 38/00 303 C22C 38/00 304

Claims (4)

(57) [Claims] 1. An Fe-BR type permanent magnet having a metal oxide film having a thickness of 0.05 μm to 0.5 μm on the surface of a Fe-BR permanent magnet, the metal oxide film being a metal of the metal film. A permanent magnet comprising a metal oxide component containing the same metal component as the component. 2. The metal coating is Al, Sn, Zn, Cu, F
The permanent magnet according to claim 1, which is made of at least one metal component selected from e, Ni, Co, and Ti. 3. The thickness of the metal coating is 0.01 μm to 50 μm.
The permanent magnet according to claim 1, wherein m is m. 4. The metal oxide film comprises at least one metal oxide component selected from Al oxide, Si oxide, Zr oxide and Ti oxide.
The permanent magnet described.