JP3176597B2 - Corrosion resistant permanent magnet and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Fe-BR permanent magnet having an excellent corrosion resistant film and a method for producing the same. More specifically, it has excellent adhesion to a magnet and has a temperature of 8
Even when left for a long time under high temperature and high humidity conditions of 0 ° C. × 90% relative humidity, the magnetic properties are not degraded, stable and high magnetic properties can be exhibited, and the coating contains hexavalent chromium. With a corrosion-resistant coating on the magnet surface
The present invention relates to a BR-based permanent magnet and a method for manufacturing the same.

[0002]

2. Description of the Related Art Fe--B--R permanent magnets, represented by Fe--B--Nd permanent magnets, are made of materials that are more abundant and inexpensive than Sm--Co permanent magnets, and Because of its high magnetic properties, it has been put to practical use in various applications. However, since the Fe-BR based permanent magnet contains highly reactive R and Fe, it is easily oxidized and corroded in the air, and when used without any surface treatment, a slight amount of acid or Corrosion progresses from the surface due to the presence of alkali, moisture, etc., and rust is generated, which leads to deterioration and variation in magnet characteristics. Furthermore, when the rusted magnet is incorporated into a device such as a magnetic circuit, the rust may scatter and contaminate peripheral components.

[0003]

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

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

Further, a method of forming an aluminum film by a vapor phase growth method and then performing a chromate treatment, that is, a so-called aluminum-chromate treatment method (proposed to improve the corrosion resistance of the Fe—BR based permanent magnet) ( 6-661
No. 73) significantly improves the corrosion resistance of the magnet. However, the chromate treatment used in this method uses hexavalent chromium, which is environmentally undesirable,
The wastewater treatment method is complicated. In addition, the film obtained by this method contains hexavalent chromium, albeit in trace amounts,
There are also concerns about the effects on the human body when handling magnets.

In the present invention, therefore, the magnetic properties are excellent even when left for a long time under high temperature and high humidity conditions of 80 ° C. × 90% relative humidity without deteriorating the magnetic properties without being deteriorated. It is an object of the present invention to provide a Fe-BR-based permanent magnet which can exhibit magnetic properties and has a corrosion-resistant film containing no hexavalent chromium on the surface of the magnet, and a method for producing the same.

[0007]

Means for Solving the Problems The present inventors have made various studies in view of the above points, and as a result, have formed an aluminum film on the surface of a Fe-BR based permanent magnet, It has been found that when a chemical conversion film containing titanium and / or zirconium as an element is formed, the chemical conversion film firmly adheres to the magnet via the aluminum film and exhibits excellent corrosion resistance.

[0008] The present invention has been made based on such knowledge, and the permanent magnet of the present invention has the following features.
The present invention is characterized in that a chemical conversion film containing at least one selected from titanium and zirconium as constituent elements, phosphorus, oxygen and fluorine is provided on the surface of a -BR type permanent magnet via an aluminum film. Claim 2
The permanent magnet according to claim 1 is the permanent magnet according to claim 1,
The aluminum film has a thickness of 0.01 μm to 50 μm. A permanent magnet according to a third aspect is characterized in that, in the permanent magnet according to the first aspect, the chemical conversion film has a thickness of 0.01 μm to 1 μm. The permanent magnet of claim 4, wherein, in the permanent magnet of claim 1, wherein, with a film per 0.1mg~100mg the content of titanium and / or zirconium in the chemical conversion film is formed on the magnet surface 1 m ² There is a feature.
According to a fifth aspect of the present invention, there is provided the permanent magnet according to the first aspect, wherein the phosphorus content in the chemical conversion film is less than the magnet surface.
0.1mg~100mg per film formed on m ²
It is characterized by being. The permanent magnet of claim 6, wherein the wherein the at permanent magnet according to claim 1, wherein the content of oxygen in the chemical conversion coating is a 0.2mg~300mg per film formed on the magnet surface 1 m ² And A permanent magnet according to a seventh aspect is the permanent magnet according to the first aspect, wherein the fluorine content in the chemical conversion film is less than the magnet surface 1.
0.05mg~100m per film formed on m ²
g. The permanent magnet according to claim 8 is the permanent magnet according to claim 1, wherein the ratio of the number of moles of phosphorus to the number of moles of titanium and / or zirconium near the surface of the chemical conversion film is greater than the ratio in the entire chemical conversion film. It is characterized by being large. Also,
According to a ninth aspect of the present invention, there is provided the permanent magnet according to the first aspect, wherein the ratio of the number of moles of phosphorus to the number of moles of titanium and / or zirconium near the surface of the chemical conversion film is 1 or more. . Further, the method for manufacturing a permanent magnet according to the present invention includes the steps of:
After an aluminum film is formed on the surface of the -BR type permanent magnet, at least one selected from a titanium compound and a zirconium compound, phosphoric acid, condensed phosphoric acid, phytic acid and phytic acid are formed on the aluminum film. A treatment liquid containing at least one selected from decomposition products and salts thereof and a fluorine compound is applied and dried to contain at least one selected from titanium and zirconium as constituent elements, phosphorus, oxygen and fluorine. Forming a chemical conversion film. An eleventh aspect of the invention is directed to the method of the tenth aspect, wherein the aluminum film is formed by a vapor phase growth method. According to a twelfth aspect of the present invention, in the method of the eleventh aspect, an aluminum film having a thickness of 0.01 μm to 50 μm is formed. The manufacturing method according to claim 13 is the manufacturing method according to claim 10, wherein the Fe-BR
The system is characterized in that a system permanent magnet and an aluminum piece are placed in a processing vessel, and both are subjected to vibration and / or agitated in the processing vessel to form an aluminum film. The manufacturing method according to claim 14 is the manufacturing method according to claim 13, wherein the film thickness is 0.0
It is characterized in that an aluminum film of 1 μm to 1 μm is formed. The production method according to claim 15 is the production method according to claim 10, wherein phosphoric acid and condensed phosphoric acid are based on at least one kind of mole number (in terms of metal) selected from a titanium compound and a zirconium compound in the treatment liquid. , Phytic acid, a hydrolyzate of phytic acid, and a salt thereof, wherein a ratio of at least one kind of moles (in terms of phosphorus) is 1 or more.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The permanent magnet of the present invention is Fe-B-
The R-based permanent magnet has a chemical conversion film containing at least one selected from the group consisting of titanium and zirconium, phosphorus, oxygen and fluorine, via an aluminum film on the surface of the permanent magnet.

The method for forming the aluminum film on the surface of the Fe-BR-based permanent magnet is not particularly limited.
However, considering that the magnet and the aluminum film are easily oxidized and corroded, the following method using a vapor phase growth method, a Fe-BR-based permanent magnet and an aluminum piece are placed in a processing vessel, and And apply vibration to both,
And / or a method of stirring both is a desirable method.

(1) Method by vapor phase epitaxy The vapor phase epitaxy that can be employed to form an aluminum film includes known methods such as vacuum deposition, ion sputtering, and ion plating. Can be The aluminum film may be formed under general conditions in each method, but the denseness of the formed film,
From the viewpoint of the uniformity of the film thickness, the film formation speed, and the like, it is desirable to employ a vacuum evaporation method or an ion plating method. In addition, cleaning, degreasing,
It goes without saying that a known cleaning treatment such as sputtering may be performed.

The temperature of the magnet at the time of film formation is 200
It is desirable that the temperature be set in the range of 500C to 500C. The temperature is 20
If the temperature is lower than 0 ° C., a film having excellent adhesion to the magnet surface may not be formed. If the temperature exceeds 500 ° C., a crack occurs in the cooling process after the film is formed, and the film peels off from the magnet. This is because there is a fear.

The thickness of the aluminum film is 0.01 μm
If it is less than 50 μm, excellent corrosion resistance may not be exhibited. If it exceeds 50 μm, not only may the production cost be increased, but also the effective volume of the magnet may be reduced, so that 0.01 μm to 50 μm is desirable. But,
0.05 μm to 25 μm is more desirable.

(2) A method in which an Fe-BR-based permanent magnet and an aluminum piece are placed in a processing vessel, and both are vibrated and / or agitated in the processing vessel. The aluminum piece to be used may have various shapes such as a needle shape (wire shape), a columnar shape, and a lump shape. From the viewpoint of efficiently generating aluminum fine powder which is a constituent source of the aluminum film, It is desirable to use a needle-shaped or column-shaped one with a sharp end.

The size (major axis) of the aluminum piece is preferably from 0.05 mm to 10 mm, more preferably from 0.3 mm to 5 mm, and still more preferably 0 mm, from the viewpoint of efficiently producing aluminum fine powder. .
5 mm to 3 mm. The aluminum pieces having the same shape and the same size may be used, or the aluminum pieces having different shapes and different sizes may be mixed and used.

The vibration and / or stirring of the magnet and the aluminum piece is desirably performed dry in consideration of the fact that both are easily oxidized and corroded.
It can be performed at room temperature. The processing vessel that can be used in the present invention does not require a complicated apparatus, and may be, for example, a processing chamber of a barrel apparatus. As the barrel device, a known device such as a rotary type, a vibration type, and a centrifugal type can be used. In the case of a rotary type, the rotation speed is 20 rpm to 50 r.
pm is desirable. In the case of the vibration type, the frequency is 50 Hz to 100 Hz, and the vibration amplitude is 0.3 mm to 10 mm.
mm. In the case of the centrifugal type, it is desirable that the rotation speed be 70 rpm to 200 rpm.

The amount of the magnet and the aluminum piece to be put in the processing container is 20 vol% to 90 vol% of the volume in the processing container.
Is desirable. If it is less than 20 vol%, the treatment amount is too small to be practical, and if it exceeds 90 vol%, it may not be possible to form a film efficiently.
Further, the ratio of the magnet and the aluminum piece put in the processing container is desirably 3 or less in terms of volume ratio (magnet / aluminum piece). If the volume ratio exceeds 3, it takes a long time to form a film, which may not be practical. Also,
Although the processing time depends on the processing amount, it is usually 1 hour to 10 hours.
Time.

According to the above-described method, aluminum fine powder generated from aluminum pieces is applied to the magnet surface to form an aluminum film. The phenomenon that the aluminum fine powder adheres to the magnet surface is considered to be a kind of mechanochemical reaction, and the aluminum fine powder adheres firmly to the magnet surface, and the resulting aluminum film shows excellent corrosion resistance. From the viewpoint of ensuring sufficient corrosion resistance, as described above,
The thickness is desirably 0.01 μm or more. Although the upper limit of the film thickness is not particularly limited, the film thickness is 1 μm.
This method is suitable as a method for forming an aluminum film having a thickness of 1 μm or less, since it takes time to form an aluminum film exceeding m.

After forming an aluminum film on the magnet surface, heat treatment can be performed to increase the adhesion between the magnet surface and the aluminum film. If the temperature of the heat treatment is lower than 200 ° C., the interface reaction between the magnet and the aluminum film may not sufficiently proceed, and the adhesion may not be improved. If the temperature exceeds 500 ° C., the magnetic properties of the magnet may be deteriorated. The aluminum film may be dissolved. Therefore, the heat treatment is desirably performed at 200 ° C. to 500 ° C., but is more desirably performed at 200 ° C. to 250 ° C. from the viewpoint of productivity and manufacturing cost.

Next, a method of forming a chemical conversion film containing at least one selected from the group consisting of titanium and zirconium, phosphorus, oxygen and fluorine on the aluminum film will be described. As the method, for example, at least one selected from a titanium compound and a zirconium compound, phosphoric acid, condensed phosphoric acid, phytic acid,
A method of applying a treatment liquid containing at least one kind selected from a hydrolyzate of phytic acid and a salt thereof and a fluorine compound, followed by drying.

[0021] The treatment liquid comprises at least one selected from a titanium compound and a zirconium compound, at least one selected from phosphoric acid, condensed phosphoric acid, phytic acid, a hydrolyzate of phytic acid and salts thereof, and a fluorine compound. It is adjusted by dissolving in

As the titanium compound contained in the treatment liquid, fluorotitanic acid, alkali metal salts, alkaline earth metal salts and ammonium salts of fluorotitanic acid, sulfates and nitrates of titanium and the like can be used. Examples of the zirconium compound include fluorozirconic acid, alkali metal salts, alkaline earth metal salts and ammonium salts of fluorozirconic acid, and sulfates and nitrates of zirconium. The content in at least one treatment liquid selected from a titanium compound and a zirconium compound is preferably 1 ppm to 2000 ppm in terms of metal, and more preferably 10 ppm to 1000 ppm.
If the content is less than 1 ppm, the chemical conversion film may not be formed, and if it is more than 2000 ppm, the cost may be increased.

As the condensed phosphoric acid contained in the treatment liquid, pyrophosphoric acid, tripolyphosphoric acid, metaphosphoric acid, ultraphosphoric acid and the like can be used. Examples of the phytic acid hydrolyzate include myo-inositol diphosphate, triphosphate, tetraphosphate, and pentaphosphate. phosphoric acid,
As the salts of condensed phosphoric acid, phytic acid, and the hydrolyzate of phytic acid, respective ammonium salts, alkali metal salts, alkaline earth metal salts, and the like can be used. phosphoric acid,
When condensed phosphoric acid and salts thereof are used, the content in these treatment solutions is 1 ppm to 2000 ppm in terms of phosphoric acid.
ppm is desirable, and 5 ppm to 1000 ppm is more desirable. If the content is less than 1 ppm, the chemical conversion film may not be formed, and if the content is more than 2000 ppm, the adhesion of the chemical conversion film to the magnet may be affected. For the same reason, when phytic acid, a hydrolyzate of phytic acid and a salt thereof are used, the content of these treatment liquids is 50 ppm in terms of phytic acid.
-10,000 ppm is desirable, and 100 ppm-500
0 ppm is more desirable.

Examples of the fluorine compound contained in the treatment solution include hydrofluoric acid, ammonium fluoride, ammonium hydrogen fluoride, and sodium fluoride in addition to the above-mentioned fluorotitanic acid and salts thereof, fluorozirconic acid and salts thereof. And sodium hydrogen fluoride. The content of the fluorine compound in the treatment solution is 10 ppm in fluorine concentration.
-10,000 ppm is desirable, and 50 ppm-5000
ppm is more desirable. If the content is less than 10 ppm, the aluminum film surface may not be efficiently etched. If the content is more than 10,000 ppm, the etching rate may be faster than the film formation rate, and uniform film formation may be difficult. .

It is desirable that the pH of the treatment liquid is adjusted to 1 to 6. If the pH is less than 1, excessive etching of the surface of the aluminum film may occur, and if it exceeds 6, the stability of the processing solution may be affected.

In the treatment liquid, in addition to the above-mentioned components, the chemical conversion treatment reactivity is improved, the stability of the treatment liquid is improved, the adhesion of the chemical conversion film to the magnet is improved, and the magnet is used when the magnet is incorporated into parts. Organic acids such as tannic acid, oxidizing agents (hydrogen peroxide, chloric acid and its salts, nitrous acid and its salts, nitric acid and its salts, tungstic acid and its And water-soluble resins such as water-soluble polyamides.

When the processing solution itself lacks storage stability, it may be adjusted as needed. Examples of the processing liquid that can be used in the present invention include a processing liquid prepared from Palcoat 3753 (product name, manufactured by Nippon Parkerizing Co., Ltd.), Palcoat 3756MA, and Palcoat 375.
6MB (All product names, manufactured by Nippon Parkerizing Co., Ltd.)
And a treatment liquid adjusted from the above.

As a method of applying the treatment liquid to the surface of the aluminum film, a dipping method, a spray method, a spin coating method, or the like can be used. At the time of coating, the temperature of the processing solution is 20
It is desirable that the temperature be in the range of ℃ to 80 ℃. If the temperature is lower than 20 ° C., the reaction may not proceed, and if it exceeds 80 ° C., the stability of the processing solution may be affected. The processing time is usually 10 seconds to 10 minutes.

After the treatment liquid is applied to the surface of the aluminum film, a drying treatment is performed. If the temperature of the drying treatment is lower than 50 ° C., it may not be possible to dry sufficiently, so that the appearance may be deteriorated or the adhesiveness to the adhesive used when the magnet is incorporated into the component may be affected. There are 250
If the temperature exceeds ℃, the formed chemical conversion film may be decomposed. Therefore, the temperature is desirably 50 ° C. to 250 ° C., but from the viewpoint of productivity and manufacturing cost, the temperature is 50 ° C. to 1 ° C.
50 ° C. is more desirable. Note that the drying time is usually 5
Seconds to 1 hour.

The chemical conversion film formed by the above-mentioned method and containing at least one selected from titanium and zirconium, phosphorus, oxygen and fluorine, is firmly adhered to the magnet via the aluminum film. Therefore, if the film thickness is 0.01 μm or more, sufficient corrosion resistance can be obtained. Also, during the chemical conversion treatment, phosphoric acid or condensed phosphoric acid in the treatment liquid is a magnet material Nd on the magnet surface.
It is considered that a passive film is formed by reacting with Al or Fe, and even if there is a portion where the degree of formation of the aluminum film is not sufficient, the corrosion resistance of this portion is compensated.
The upper limit of the film thickness of the chemical conversion film is not limited, but from the viewpoint of the request based on the downsizing of the magnet itself and the production cost,
1 μm or less is desirable, and 0.3 μm or less is more desirable.

The content of titanium and / or zirconium in the chemical conversion coating is preferably 0.1 mg to 100 mg per coating formed on 1 m ² of the magnet surface.
0 mg is more desirable. If the content is less than 0.1 mg, sufficient corrosion resistance may not be obtained.
If the amount is larger than g, the cost may be increased.

The content of phosphorus in the chemical conversion film is determined based on the magnet surface 1
0.1mg~100mg per film formed on m ²
Is desirable, and 1 mg to 50 mg is more desirable. If the content is less than 0.1 mg, sufficient corrosion resistance may not be obtained, and if the content is more than 100 mg, the adhesion to the adhesive used when the magnet is incorporated into the component may be affected. It is.

The oxygen in the chemical conversion film is added to the treatment liquid in the form of bonding with titanium, zirconium and phosphorus, and for the purpose of improving the adhesiveness with the adhesive used when assembling the magnet into parts. Is present in the chemical conversion film as a constituent element of the organic acid. The oxygen content in the conversion coating is 0.2 m per coating formed on 1 m ^{2 of} magnet surface.
g to 300 mg is desirable. If the content is less than 0.2 mg, sufficient corrosion resistance may not be obtained,
If the amount is more than 0 mg, there is a possibility that the adhesiveness to an adhesive used when the magnet is incorporated into the component may be affected.

Fluorine in the chemical conversion film is caused by free fluorine ions present in the processing solution for etching the surface of the aluminum film and those bonded to Zr such as ZrF ₄ HPO _4. It is taken into the film at the time of formation. The content of fluorine in the chemical conversion film is set to 0.1 per film formed on 1 m ² of the magnet surface.
05 mg to 100 mg is desirable, and 0.1 mg to 50 m
g is more desirable. If the content is less than 0.05 mg, sufficient corrosion resistance may not be obtained, and 100 mg
If the amount is too large, there is a possibility that the adhesion to the adhesive used when the magnet is incorporated into the component may be affected.

Among the chemical conversion films formed by the above method and containing at least one selected from the group consisting of titanium and zirconium, phosphorus, oxygen and fluorine, those near the film surface (for example, from the film surface to the surface from the film surface to 0%). (A thickness region of 0.002 μm) in a film in which the ratio of the number of moles of phosphorus to the number of moles of titanium and / or zirconium is greater than the ratio in the whole film, Is preferably a film having a molar ratio of 1 or more, preferably 2 or more, more preferably 3 or more. Even when the coating comes in contact with moisture, the phosphoric acid and condensed phosphoric acid that are stably present in the vicinity of the coating surface capture moisture and make it possible for the moisture that causes corrosion to reach the magnet surface. This is because it is considered that it can be further suppressed. In order to form such a film, hydrolysis of phosphoric acid, condensed phosphoric acid, phytic acid, and phytic acid with respect to at least one type of mole number (in terms of metal) selected from a titanium compound and a zirconium compound in the treatment liquid. It is desirable to use a processing solution in which the ratio of the number of moles (in terms of phosphorus) of at least one selected from a product and a salt thereof is 1 or more.

As a pre-process for forming a chemical conversion film on the aluminum film, shot peening (a method of modifying the surface by colliding hard particles) may be performed. By performing shot peening, the aluminum film can be smoothed, and a chemical conversion film having excellent corrosion resistance can be easily formed even with a thin film. The powder used for shot peening preferably has a hardness equal to or higher than the hardness of the formed aluminum film, and includes, for example, a spherical hard powder having a Mohs hardness of 3 or more, such as a steel ball or a glass bead. When the average particle size of the powder is less than 30 μm, the pressing force against the aluminum film is small, and a long time is required for the treatment. On the other hand, 30
If it exceeds 00 μm, the surface roughness may be too rough and the finished surface may be non-uniform. Therefore, the average particle size of the powder is desirably 30 μm to 3000 μm.
μm to 2000 μm is more desirable. The injection pressure in shot peening is 1.0 kg / cm ^{2 to} 5.0 kg.
/ Cm ² is desirable. If the injection pressure is less than 1.0 kg / cm ² , the pressing force on the metal film is small and it takes time to process, and if it exceeds 5.0 kg / cm ² , the pressing force on the metal film becomes non-uniform and the surface roughness increases. This is because the degree of deterioration may be caused. The injection time in shot peening is preferably 1 minute to 1 hour. If the injection time is less than 1 minute, uniform treatment may not be performed on the entire surface, and if it exceeds 1 hour, the surface roughness may be deteriorated.

The rare earth element (R) in the Fe—BR permanent magnet used in the present invention is Nd, Pr, D
at least one of y, Ho, Tb, and Sm, or La, Ce, Gd, Er, Eu, Tm, Yb,
A material containing at least one of Lu and Y is desirable.
In general, one kind of R is sufficient, but in practice, a mixture of two or more kinds (such as misch metal and dymium) can be used for convenience and other reasons. F
The content of R in the eBR type permanent magnet is 10 atomic%.
If it is less than 1, the crystal structure becomes a cubic structure having the same structure as that of α-Fe, so that high magnetic properties, particularly high coercive force (iHc)
On the other hand, if the content exceeds 30 atomic%, the amount of R-rich nonmagnetic phase increases, the residual magnetic flux density (Br) decreases, and a permanent magnet having excellent characteristics cannot be obtained. Is desirably 10 at% to 30 at%.

When the Fe content is less than 65 atomic%, B
If the value of r decreases and exceeds 80 atomic%, a high iHc cannot be obtained. Therefore, the content of 65 to 80 atomic% is desirable.
Further, by replacing part of Fe with Co, the temperature characteristics can be improved without impairing the magnetic characteristics of the obtained magnet. However, when the amount of Co exceeds 20% of Fe, the magnetic characteristics become poor. It is not desirable because it deteriorates. When the amount of Co substitution is 5 atomic% to 15 atomic%, Br increases in comparison with the case where no substitution is made, and thus 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, high iHc cannot be obtained, and 28 atomic%
If it exceeds 0.005%, a B-rich non-magnetic phase increases, and Br decreases, so that a permanent magnet having excellent characteristics cannot be obtained.
The content of about 28 atomic% is desirable. Further, in order to improve the manufacturability of the magnet and to reduce the price, the content of P of 2.0 wt% or less;
At least one of S at 0 wt% or less may be contained in a total amount of 2.0 wt% or less. Further, by replacing a part of B with 30 wt% or less of C, the corrosion resistance of the magnet can be improved.

Further, Al, Ti, V, Cr, Mn, B
i, Nb, Ta, Mo, W, Sb, Ge, Sn, Zr,
Addition of at least one of Ni, Si, Zn, Hf, and Ga is effective in improving the coercive force and the squareness of the demagnetization curve, improving the manufacturability, and reducing the cost. In order to make the maximum energy product (BH) max equal to or more than 20 MGOe, at least 9 kG of Br is required. Therefore, it is preferable to add Br in a range that satisfies the above condition. It should be noted that the Fe-BR-based permanent magnet may contain impurities inevitable in industrial production in addition to R, Fe, and B.

Further, Fe-B used in the present invention
-Among R-based permanent magnets, the average crystal grain size is 1 μm to 80 μm.
The compound having a tetragonal crystal structure in the range of m as a main phase and containing 1% to 50% by volume of a nonmagnetic phase (excluding an oxide phase) is characterized by iHc ≧ 1kO
e, 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 chemical conversion film of the present invention. By adopting such a configuration, the characteristics of the chemical conversion film can be enhanced or supplemented, or further functionality can be imparted.

[0043]

For example, as described in U.S. Pat. No. 4,770,723, 17Nd-1Pr obtained by pulverizing a well-known casting ingot, performing pulverization, forming, sintering, heat treatment and surface processing. -75Fe-7
The following experiment was performed using a sintered magnet having a B composition and a size of 23 mm × 10 mm × 6 mm (hereinafter referred to as “magnet test piece”). In the following experiments, the film thickness of the aluminum film was measured using a fluorescent X-ray film thickness meter (the device was SFT-
7000: manufactured by Seiko Instruments Inc.). The film thickness of the chemical conversion film was determined from the analysis of the film in the depth direction by X-ray photoelectron spectroscopy (XPS) (ESCA-850: manufactured by Shimadzu Corporation). The content of each component in the film was measured by X-ray fluorescence intensity (the device used was RIX-3000: manufactured by Rigaku Corporation). The present invention is not limited to application to Fe-BR-based sintered magnets, but can also be applied to Fe-BR-based bonded magnets.

EXPERIMENTAL EXAMPLE 1: The magnet body test piece was evacuated to 1 × 10 ⁻⁴ Pa or less in the vacuum vessel, and the Ar gas pressure was set to 1 × 10 ⁻⁴ Pa or less.
0 Pa, bias voltage -400 V, 35 minutes,
Sputtering was performed to clean the magnet surface. Ar gas pressure 0.2 Pa, bias voltage -50 V, magnet temperature 25
Under a condition of 0 ° C., using metal aluminum as a target, arc ion plating was performed for 15 minutes to form an aluminum film on the magnet surface and allowed to cool. The thickness of the obtained aluminum film was 0.5 μm. Pal coat 3753 (product name, manufactured by Nippon Parkerizing Co., Ltd.)
35 g was dissolved in 1 liter of water to obtain a treatment solution (pH
3.8). A magnet having an aluminum film on the magnet surface is immersed in the treatment solution at a bath temperature of 40 ° C. for 1 minute to form a chemical conversion film, and then subjected to a drying treatment at 100 ° C. for 20 minutes. 0.1 μm thick
A titanium-containing chemical conversion film was formed. The titanium content in the conversion coating was 10 mg (per 1 m ² on the magnet surface), the phosphorus content was 7 mg (same), the oxygen content was 21 mg (same),
The fluorine content was 2 mg (same). The magnet having a titanium-containing chemical conversion film on the magnet surface via an aluminum film obtained by the above method is left for 300 hours under a high-temperature and high-humidity condition of a temperature of 80 ° C and a relative humidity of 90% to accelerate corrosion resistance. The test was performed. Table 1 shows the magnetic properties before and after the test and the appearance change after the test. As a result, the magnet obtained has a magnetic property,
It was found that the required corrosion resistance was sufficiently satisfied without substantially deteriorating the appearance.

Experimental Example 2: After cleaning the magnet test piece under the same conditions as in Experimental Example 1,
Under conditions of r gas pressure 1 Pa and voltage 1.5 kV, an aluminum wire was used as a coating material, and the aluminum wire was heated to evaporate, ionized, and ionized for 1 minute.
An aluminum film was formed on the surface of the magnet by an ion plating method and allowed to cool. The thickness of the obtained aluminum film was 0.9 μm. Then, together with the pressurized gas composed of N ₂ gas, the average particle size is 120 μm, and the Mohs hardness is 6
The spherical glass bead powder was sprayed at a pressure of 1.5 kg / cm ^2.
For 5 minutes at the aluminum coating surface
Shot peening was applied. Pal coat 3756MA
And 10 g each of Palcoat 3756MB (both manufactured by Nippon Parkerizing Co., Ltd.) were dissolved in 1 liter of water to obtain a treatment liquid (the ratio of the number of moles of phosphorus to the number of moles of zirconium was 6.2 / pH 3.2). After dipping the magnet having an aluminum film on the magnet surface at a bath temperature of 50 ° C. for 1 minute and 30 seconds in this treatment liquid to form a chemical conversion film, a drying treatment is performed at 120 ° C. for 20 minutes to obtain an aluminum film. A zirconium-containing chemical conversion film having a thickness of 0.07 μm was formed thereon. The zirconium content in the conversion coating was 16 mg (per 1 m ^{2 of} magnet surface),
Phosphorus content is 11mg (same), oxygen content is 50mg
(The same), the fluorine content was 3 mg (the same). Obtained by the above method, on the magnet surface, via an aluminum film, for a magnet having a zirconium-containing conversion coating,
An accelerated corrosion resistance test was performed under the same conditions as in Experimental Example 1. Table 1 shows the results. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance.

Experimental Example 3: 150 magnet body test pieces (apparent capacity: 0.5 liter, weight: 1.6 kg) and diameter: 0.8
A 1 mm long, 1 mm long cylindrical aluminum piece (20 liters in apparent capacity, 100 kg in weight) is charged into a processing chamber of a 50 liter vibrating barrel device (total input volume is 40 vol% of the processing chamber volume), and the frequency is 60 Hz. The treatment was performed dry for 5 hours under the condition of a vibration amplitude of 1.8 mm to form an aluminum film on the magnet surface. The thickness of the obtained aluminum film was 0.05 μm. After dipping the magnet having an aluminum coating on the magnet surface at a bath temperature of 50 ° C. for 1 minute and 30 seconds in the treatment liquid described in Experimental Example 2 to form a chemical conversion coating, a drying treatment is performed at 120 ° C. for 20 minutes. As a result, a zirconium-containing chemical conversion film having a thickness of 0.08 μm was formed on the aluminum film. The zirconium content in the conversion coating was 16 mg (per 1 m ^{2 of} magnet surface), the phosphorus content was 12 mg (same as above), and the oxygen content was 38.
mg (same) and the fluorine content was 3 mg (same). A magnet having a zirconium-containing chemical conversion coating on the magnet surface via an aluminum coating obtained by the above method was subjected to an accelerated corrosion resistance test under the same conditions as in Experimental Example 1. Table 1 shows the results. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance.

Experimental Example 4: After cleaning the 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 aluminum film on the magnet surface, and then allowed to cool. The thickness of the obtained aluminum film is 5μ.
m. By dipping the magnet having an aluminum film on the magnet surface at a bath temperature of 40 ° C. for 1 minute to form a chemical conversion film in the treatment liquid described in Experimental Example 1, and then performing a drying treatment at 100 ° C. for 20 minutes, A titanium-containing chemical conversion film having a thickness of 0.09 μm was formed on the aluminum film. The titanium content in the conversion coating was 9 mg (per 1 m ^{2 of the} magnet surface), the phosphorus content was 6 mg (same as above), and the oxygen content was 2
0 mg (same) and the fluorine content was 2 mg (same).
The magnet having a titanium-containing chemical conversion film on the surface of the magnet obtained through the above-described method via an aluminum film was heated to a temperature of 8 ° C.
The sample was allowed to stand for 1000 hours under a high temperature and high humidity condition of 0 ° C. × 90% relative humidity, and an accelerated corrosion resistance test was performed. Table 2 shows the magnetic properties before and after the test and the appearance change after the test. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance without substantially deteriorating in magnetic properties and appearance even when left under a high temperature and high humidity condition for a long time.

Experimental Example 5: An aluminum film was formed on the magnet surface by the ion plating method under the same conditions as in Experimental Example 2 for 10 minutes and allowed to cool. The thickness of the obtained aluminum film was 10 μm. Thereafter, spherical glass bead powder having an average particle size of 120 μm and a Mohs hardness of 6 was sprayed onto the aluminum film surface at an injection pressure of 1.5 kg / cm ^{2 for} 5 minutes together with a pressurized gas composed of N ₂ gas. Shot peening was applied. After dipping the magnet having an aluminum coating on the magnet surface at a bath temperature of 50 ° C. for 1 minute and 30 seconds in the treatment liquid described in Experimental Example 2 to form a chemical conversion coating, a drying treatment is performed at 120 ° C. for 20 minutes. As a result, a zirconium-containing chemical conversion film having a thickness of 0.07 μm was formed on the aluminum film. The zirconium content in the conversion coating was 15 mg (per 1 m ^{2 of} magnet surface), and the phosphorus content was 12 mg.
(The same), the oxygen content was 47 mg (the same), and the fluorine content was 2 mg (the same). A corrosion resistance accelerated test was conducted on the magnet having a zirconium-containing chemical conversion coating via an aluminum coating on the magnet surface obtained by the above method under the same conditions as in Experimental Example 4. Table 2 shows the results. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance. When the ratio of the number of moles of phosphorus to the number of moles of zirconium in the thickness region of 0.002 μm from the coating surface of the zirconium-containing chemical conversion coating was measured by X-ray photoelectron spectroscopy (XPS) (the device was ESCA-850). : Using Shimadzu Corporation). On the other hand, based on the number of moles of zirconium and the number of moles of phosphorus measured by the fluorescent X-ray intensity, the moles of zirconium in the entire chemical conversion coating are determined.
When the ratio of the number of moles of phosphorus to the number was calculated,
It was 2.

Experimental Example 6: A magnet body test piece was cleaned under the same conditions as in Experimental Example 1, and then an ingot of metallic aluminum was used as a coating material under an Ar gas pressure of 1 × 10 ⁻² Pa and heated. To form an aluminum film on the magnet surface by vacuum evaporation for 50 minutes,
Allowed to cool. The thickness of the obtained aluminum film was 8 μm. The magnet having an aluminum coating on the magnet surface was added to the treatment liquid described in Experimental Example 2 at a bath temperature of 50 ° C. for 1 minute 30 minutes.
After forming a chemical conversion film by dipping for 2 seconds, a zirconium-containing chemical conversion film having a thickness of 0.06 μm was formed on the aluminum film by performing a drying treatment at 120 ° C. for 20 minutes. The zirconium content in the conversion coating is 15 mg
(Per upper magnet surface 1 m ^2), the phosphorus content is 13mg
(The same), the oxygen content was 35 mg (the same), and the fluorine content was 2 mg (the same). A corrosion resistance accelerated test was conducted on the magnet having a zirconium-containing chemical conversion coating via an aluminum coating on the magnet surface obtained by the above method under the same conditions as in Experimental Example 4. Table 2 shows the results. As a result, it was found that the obtained magnet sufficiently satisfied the required corrosion resistance.

[0050]

[Table 1]

[0051]

[Table 2]

Comparative Example 1: Magnet specimen was degreased and pickled,
It was immersed in a treatment solution consisting of 4.6 g / l of zinc and 17.8 g / l of a phosphate at a bath temperature of 70 ° C. to form a 1 μm-thick phosphate film on the surface of the magnet. The obtained magnet was subjected to a corrosion resistance acceleration test under the same conditions as in Experimental Example 1. Table 1 shows the results. As a result, the obtained magnet was deteriorated in magnetic properties and rusted.

Comparative Example 2 A test piece for magnet body was subjected to an accelerated corrosion resistance test under the same conditions as in Experimental Example 1. Table 1 shows the results. As a result, the magnet body test piece caused deterioration of magnetic properties and rust.

Comparative Example 3: A magnet having an aluminum film on the surface of the magnet subjected to shot peening in Experimental Example 5 was subjected to a corrosion resistance acceleration test under the same conditions as in Experimental Example 4.
Table 2 shows the results. As a result, the resulting magnet is
Deterioration of magnetic properties and rusting were caused.

Comparative Example 4: After cleaning the magnet having an aluminum film on the surface of the magnet subjected to shot peening in Experimental Example 5, 300 g / l of sodium hydroxide, 40 g / l of zinc oxide, and 1 g / l of ferric chloride. , Rossell salt 30g /
l, immersed in a treatment solution at a bath temperature of 23 ° C. to replace the surface of the aluminum film with zinc. Furthermore, nickel sulfate 240g /
l, nickel chloride 48g / l, nickel carbonate appropriate amount (pH
Adjustment), bath temperature 55 ° C consisting of boric acid 30 g / l, pH
Using a plating solution of 4.2, electroplating was performed under the conditions of a current density of 1.8 A / dm ² to form a nickel film having a thickness of 0.9 μm on an aluminum film whose surface was replaced with zinc. . The obtained magnet was subjected to a corrosion resistance acceleration test under the same conditions as in Experimental Example 4. Table 2 shows the results.
As a result, the resulting magnet causes deterioration of magnetic properties,
Part of the nickel film peeled off.

[0056]

According to the present invention, a chemical conversion coating containing at least one selected from zirconium and titanium, phosphorus, oxygen and fluorine as constituent elements is provided on the surface of the Fe-BR based permanent magnet of the present invention via an aluminum coating. The permanent magnet has excellent corrosion resistance because the chemical conversion film is firmly adhered to the magnet via the aluminum film, and has a temperature of 80 ° C.
Even when left for a long time under high-temperature and high-humidity conditions of 90% relative humidity, the magnetic properties are not deteriorated and stable and high magnetic properties are exhibited. Further, hexavalent chromium is not contained in the film.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01F 1/08 C22C 38/00 C23C 14/08 H01F 1/053

Claims (15)

(57) [Claims] 1. A Fe—BR—based permanent magnet having a chemical conversion film containing at least one selected from titanium and zirconium as constituent elements, phosphorus, oxygen and fluorine, on an aluminum film surface via an aluminum film. And a permanent magnet. 2. The thickness of an aluminum film is 0.01 μm.
2. The permanent magnet according to claim 1, wherein the thickness of the permanent magnet is from 50 to 50 [mu] m. 3. The chemical conversion film has a thickness of 0.01 μm to 1 μm.
The permanent magnet according to claim 1, wherein 4. The permanent magnet according to claim 1, wherein the content of titanium and / or zirconium in the chemical conversion coating is 0.1 mg to 100 mg per coating formed on 1 m ^{2 of the} magnet surface. 5. The method according to claim 1, wherein the content of phosphorus in the chemical conversion coating is 1% on the magnet surface.
0.1mg~100mg per film formed on m ²
The permanent magnet according to claim 1, wherein 6. The method according to claim 1, wherein the oxygen content in the chemical conversion film is less than the magnet surface.
0.2mg~300mg per film formed on m ²
The permanent magnet according to claim 1, wherein 7. The fluorine content in the chemical conversion film is 0.05 mg to 100 mg per film formed on 1 m ^{2 of the} magnet surface.
The permanent magnet according to claim 1, wherein the amount is mg. 8. The permanent magnet according to claim 1, wherein the ratio of the number of moles of phosphorus to the number of moles of titanium and / or zirconium near the surface of the chemical conversion film is larger than the ratio in the entire chemical conversion film. 9. The method according to claim 1, wherein the ratio of the number of moles of phosphorus to the number of moles of titanium and / or zirconium in the vicinity of the surface of the chemical conversion film is 1 or more.
The permanent magnet as described. 10. An aluminum film is formed on the surface of a Fe—BR-based permanent magnet, and at least one selected from a titanium compound and a zirconium compound, phosphoric acid, condensed phosphoric acid, and phytin are formed on the aluminum film. acid,
At least one selected from titanium and zirconium as constituent elements is applied by applying and drying a treatment liquid containing at least one selected from phytic acid hydrolysates and salts thereof and a fluorine compound,
A method for producing a permanent magnet, comprising forming a chemical conversion film containing phosphorus, oxygen and fluorine. 11. The method according to claim 10, wherein the aluminum film is formed by a vapor growth method. 12. The method according to claim 11, wherein an aluminum film having a thickness of 0.01 μm to 50 μm is formed. 13. An aluminum film is formed by placing an Fe—BR-based permanent magnet and an aluminum piece in a processing container, and applying vibration and / or stirring both in the processing container. The method according to claim 10, wherein: 14. The method according to claim 13, wherein an aluminum film having a thickness of 0.01 μm to 1 μm is formed. 15. A phosphoric acid, a condensed phosphoric acid, a phytic acid, a hydrolyzate of phytic acid and a salt thereof based on at least one kind of mole number (in terms of metal) selected from a titanium compound and a zirconium compound in a treatment liquid. 11. The production method according to claim 10, wherein a ratio of at least one selected mole content (in terms of phosphorus) is 1 or more.