JP2002198240A - R-Fe-B PERMANENT MAGNET AND MANUFACTURING METHOD THEREFOR - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an R-Fe-B permanent magnet which can be used in an environment where the temperature in the environment fluctuates very much and can very effectively contribute to the recent emphasized energy conservation, and to provide a method of manufacturing the magnet. SOLUTION: This R-Fe-B permanent magnet (where, R denotes at least one kind of rare-earth element, including Sc and Y) is covered with a metal coating film. The coating film is composed of a first plated metal coated film, having a thickness of 0.1-1.0 μm and substantially containing no pores, and a second plated metal coating film, including pores having major axes of 0.1-1.5 μm in length at their cross sections.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an R-type light emitting device suitable for use in an environment having a rapid temperature change or a continuous high temperature environment.
The present invention relates to an Fe—B-based permanent magnet (R is at least one of rare earth elements including Sc and Y, and the same applies hereinafter) and a method for producing the same.

[0002]

2. Description of the Related Art Rare-earth permanent magnets are widely used in the fields of electricity and electronics due to their excellent magnetic properties and economical efficiency. Is eagerly awaited. Among them, Nd-based rare earth permanent magnets are particularly inexpensive because compared with Sm-based rare-earth permanent magnets, Nd, which is a main element, is more abundant than Sm, and it does not require a large amount of expensive Co. In terms of characteristics, it is an extremely excellent permanent magnet material, far superior to Sm-based rare-earth permanent magnets. It is going to be widely used in fields where ferrites or electromagnets have been used. However, rare earth metal materials such as Nd generally oxidize easily in a very short period of time in humid air, and consequently the deterioration of magnetic properties and contamination caused by falling off of the magnet material are disadvantageous. Exists as Therefore, in general use, as a protective coating on the surface of the magnet, a plated metal coating as disclosed in JP-A-60-54406, an inorganic coating as disclosed in JP-A-9-63833, It has been proposed to apply an organic coating or the like as disclosed in JP-A-9-180922. Also, recently, a problem that the magnet is corroded and deteriorated by a plating solution remaining between the coating and the magnet is disclosed in Japanese Patent Application Laid-Open No. 7-7404.
As disclosed in Japanese Patent Application Publication No. 3 (1993) -3, a method of dry-coating the magnet surface with a metal deposition film of aluminum or the like using ion plating has been proposed, and measures against oxidation deterioration, which has been a problem in the past, are being taken. is there.

However, with the expansion of applications, R-
The handling of Fe-B permanent magnets has also changed drastically, and in recent motor assembly, shrink-fitting techniques such as mounting magnets on parts heated to around 400 ° C and fixing them have been used. While exhibiting the conventional oxidation resistance even in such a high temperature environment, in addition, from room temperature to
New durability is required, such as heat shock resistance of about 400 ° C., heat resistance of about 400 ° C., and heat deterioration resistance in which magnetic properties are not extremely reduced even when exposed to such high temperatures. .

[0004] With respect to such demands, particularly, from room temperature to 40
Although the thermal shock resistance at about 0 ° C. has not been considered so far, there is a difference in the degree. However, in the conventional protective coating, the thermal expansion and shrinkage of the magnet substrate and the coating metal are greatly different, and the coating itself has Due to the effects of stress and the decrease in film strength caused by the structural transformation that occurs when the film is further cooled, the film may have cracks, cracks, or blisters, and may further develop peeling of the film or thermal decomposition of the film itself. As a result, problems such as significantly reducing the protection function occur,
The demands have not been able to be fully satisfied.

[0005] Regarding the problem caused by the difference between expansion and contraction, the magnet is a sintered body of an alloy composed of a plurality of components mainly composed of Nd and Fe, and the shape of the sintered body varies widely. It is difficult to match the expansion and contraction rates of the magnet base and the coating metal because of the fact that there is no sufficient solution.For problems caused by the stress of the protective coating, reduce the stress in the coating. The method of adding such an element is effective, but when such an additive is used, there is an adverse effect such as making the coating brittle or easily corroded. Was.

[0006]

Therefore, in the present invention,
In order to expand the application range of R-Fe-B permanent magnets,
In addition to the function of the coating that has been required in the past, even in use under an environment with an extreme temperature difference or in use at high temperatures, the corrosion resistance is maintained because there is no cracking, blistering or peeling of the coating. It is an object to provide a B-based magnet and a method for manufacturing the magnet.

[0007]

Means for Solving the Problems and Embodiments of the Invention The present inventor has studied to achieve the above object and to solve the disadvantages and disadvantages of the prior art. After protection with a film, it is effective to deposit and protect a plating metal film having pores inside, in which case these plating metal films are formed using a copper pyrophosphate electroplating solution having a specific composition. Have been found to be preferable, and have completed the present invention.

Accordingly, the present invention provides an R-
In the Fe-B (R is at least one kind of rare earth element including Sc and Y) -based permanent magnet, the metal layer has substantially no pores in the first layer having a thickness of 0.1 to 1.0 μm. R-Fe-B permanent coating characterized by coating a plated metal film and further coating thereon a second layer of plated metal film containing pores having a major axis of 0.1 to 1.5 [mu] m in cross section. The surface area of the magnet and R-Fe-B (R is at least one of rare earth elements including Sc and Y) -based permanent magnets
A first-layer plating metal film having a thickness of 1.0 μm and having substantially no voids is coated, and the major axis of the cross-section is 0.1 μm.
Provided is a method for producing an R-Fe-B-based permanent magnet, which comprises coating a second-layer plated metal film containing pores of up to 1.5 µm.

In this case, on the second plating metal film,
At least one of a nickel plating film, a nickel alloy plating film, and a composite nickel plating film in which composite particles are eutectoid can be coated. The first and second plating metal films are preferably formed by copper pyrophosphate electroplating. In this case, the formation of the first plating metal film is performed using potassium pyrophosphate or sodium pyrophosphate. A plating pretreatment using an aqueous solution containing 1 to 10 wt% is performed, and then potassium pyrophosphate or sodium pyrophosphate is 200 to 300 g / l, and copper pyrophosphate is 1
0-30 g / l, potassium citrate or sodium citrate 10-30 g / l, ammonia 0.1-1 m
1 / l of an aqueous solution of electrolytic copper is applied, and the formation of the second plating metal film is performed by using potassium pyrophosphate or sodium pyrophosphate for 20 minutes.
0 to 450 g / l, copper pyrophosphate 60 to 100 g / l,
40-8 potassium citrate or sodium citrate
It is effective to perform electrolytic copper plating using an aqueous solution containing 0 g / l and ammonia of 0.5 to 5 ml / l.

Hereinafter, the present invention will be described in more detail.

In the R-Fe-B permanent magnet of the present invention, a plated metal film having substantially no voids is formed as a first layer metal film on the surface of the permanent magnet, and a second layer metal film is formed thereon. A plated metal film containing pores is formed as a metal film,
If necessary, a nickel-based plating film is formed on the third layer.

The metal film having pores therein in the present invention is a metal film containing pores having a major axis of 0.1 to 1.5 μm, and a metal film having substantially no pores. Is a coating in which these vacancies are hardly observed even when using a device that can be observed on the micron order such as an electron microscope. The existence of things is acceptable. Further, the vacancy in the present invention is not a pinhole generated due to foreign matter or bubbles attached to the substrate,
A closed hole intentionally created under specific plating conditions.

Here, the permanent magnet (sintered magnet) to which the present invention is applied is of the R-Fe-B type, and R is selected from at least one of the rare earth elements including Sc and Y. Are Sc, Y, La, Ce, Pr, Nd, Pm, Sm, E
u, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu
At least one rare earth metal, and the content is 5 to 40 wt%. Further, the sintered magnet body contains 50 to 90 wt% of Fe, 15 wt% or less of Co, 0.2 to 8 wt% of B, and Ni, Nb, and A as additives.
1, Ti, Zr, Cr, V, Mo, Si, Sn, Ga,
8 wt% of at least one element selected from Cu and Zn
% Or less, and additionally contains industrially unavoidable impurities such as C, O, P, S, and N.

In the present invention, a first-layer plating film having substantially no voids is formed on the magnet, and a second-layer plating film containing voids is formed thereon. In this case, when a coating having pores inside is directly applied to the magnet, a slight plating solution remains in the pores. If there are vacancies in the vicinity, there is a possibility that the plating solution will stain over time, and as a result, magnet corrosion will occur.
After protecting the magnet by depositing about 1 to 1 μm, a metal film containing pores having thermal shock resistance is deposited thereon.

The plating solution for depositing the first layer of the coating is desirably as hard to corrode as possible because the magnet is directly shaken. However, in the case of the R-Fe-B permanent magnet of the present invention, the pH of the plating solution is When considered on the basis of, generally, the plating solution tends to be easily corroded by an acidic plating solution, and hardly corroded by a weakly acidic to alkaline plating solution. Is good. The plating bath having such a liquid property includes electroless nickel phosphorus plating, electroless copper plating, pyrophosphate copper electroplating, tin pyrophosphate plating, tin nickel pyrophosphate plating, and tin lead organic acid plating. Among these, it is preferable to form a first layer using a copper pyrophosphate plating solution having a specific composition after performing electroplating, particularly a specific pretreatment described later.

In this case, the film thickness of the first layer is 0.1
To 1.0 μm. If the thickness is less than 0.1 μm, it is not possible to prevent plating stains from coming out of the holes included in the second plating film. If it is thicker than 1.0 μm, the possibility of peeling off from the magnet substrate due to thermal shock increases. The thickness of the film was measured with a fluorescent X-ray measuring instrument using a calibration curve method.
You can check.

Next, the plating solution for forming the plating film containing the pores of the second layer is not particularly limited, but is an electroplating solution, particularly an electrocopper plating solution, and especially a copper pyrophosphate electroplating having a specific composition described later. Preferably, it is a liquid.

The thickness of the second plating film is appropriately selected, but is preferably about 3 to 10 μm. The pores have a major axis of 0.1 to 1.5 μm. When the major axis of the pores is larger than 1.5 μm, the thickness of the thinnest portion of the coating becomes insufficient, and the corrosion resistance and abrasion resistance are extremely reduced. When it is smaller than 0.1 μm, the ability to mitigate thermal shock is insufficient. Would.

The holes present in the plating film are made to exist independently of each other to prevent the plating solution remaining inside the holes from seeping into the plating surface or the magnet substrate.
The shape of the hole may be such that its cross section is a perfect circle or an ellipse.

Further, the number of vacancies, but it may be difficult to determine the exact number for collapsing a portion of the pores by measuring pretreatment, the film cross-section, approximately 16 / [mu] m ² or less, More preferably, it is 3 to 10 particles / μm ² .

The film having pores tends to be slightly inferior in corrosion resistance and abrasion resistance as compared with a film containing almost no pores. Two films containing almost no voids on the film
The thickness may be about 10 to 10 μm.

The type of film is not particularly limited as long as it can be deposited by a known plating method such as Ni or Cu, but it is assumed that the film is heated to about 400 ° C. The coating must be durable, and it is desirable to perform nickel plating as the third plating film.

As such nickel-based plating, nickel alloy plating such as nickel plating, nickel-phosphorus plating, nickel-boron plating, nickel-zinc plating, and composite particles (eutectoid particles) such as SiC and WC are dispersed.
Examples include composite plating in which these composite particles are eutectoid in the nickel film. These may be electroplating or electroless plating, but are preferably electroplating.

When an R-Fe-B-based permanent magnet having two or more, if necessary, three or more plating films as described above is obtained by electroplating, a pre-treatment step, activation A processing step is performed, and then an electroplated metal film is deposited. In the pretreatment step, rust removal, degreasing, and removal of inert substances are performed sequentially in the conventional plating treatment, but conditions are appropriately changed according to the magnet composition. The next activation treatment step is performed in order to remove the influence of the pretreatment and improve the plating deposition in the next step. Specifically, it is as follows.

[Pretreatment Step] Rust removal Rust removal is performed for the purpose of removing the oxide film on the surface of the rare earth magnet. Rust, dirt and other impurities on the magnet surface are removed by polishing with a grindstone or buff, barrel polishing, sand blasting or honing, brushing, etc. . 2. Solvent degreasing Solvent degreasing is performed for the purpose of removing dirt from the surface of the rare earth magnet due to oils and fats, and is performed by immersing the magnet in an organic solvent such as an ester, ether, or alcohol, or spraying the solvent. . 3. Alkaline degreasing Alkaline degreasing is generally performed following the above solvent degreasing, and is performed for the purpose of removing dirt from oils and fats on the magnet surface, and includes potassium hydroxide, sodium hydroxide,
An aqueous solution containing at least one of sodium carbonate, potassium carbonate, sodium orthosilicate, sodium metasilicate, trisodium phosphate, and a chelating agent in a total amount of 5 g / l to 200 g / l, and a small amount of a surfactant Is added, and then the rare earth magnet is immersed in the mixture while being heated to a temperature not lower than room temperature and not higher than 90 ° C. 4. Removal of Inert Substances Pickling is performed to remove impurities such as oxide films that could not be removed in the previous step, inactive films newly generated in the previous step, and attached metal salts.

The treatment liquid is an aqueous solution containing 1 to 40% by weight of sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, oxalic acid, acetic acid, formic acid, citric acid, tartaric acid and at least one of these potassium salts and sodium salts in total. Is in the range of 10 to 60 ° C., and the magnet is immersed in this for treatment.

In the above-mentioned four operations, ie, operations 1 to 4, at least one operation is selected according to the amount of dirt on the surface of the magnet.
It is desirable to perform a combination of more than one type, and the processing time of each can be appropriately changed. In addition, after each treatment, it is necessary to thoroughly wash with water.

[Activation Treatment Step] The activation treatment is performed to increase the surface energy state of the rare-earth magnet in advance, and to improve the adhesion between the plating film and the magnet.

The chemical used for the activation treatment is an aqueous solution containing at least one of phosphoric acid, oxalic acid, acetic acid, formic acid, citric acid, tartaric acid and at least one of these potassium salts and sodium salts in total. However, in order to further enhance the effect, anionic interface such as alkali salts of higher fatty acids such as sodium laurate, sodium myristate, sodium palmitate and sodium stearate, alkyl sulfonates, alkyl aryl sulfonates, etc. Activators or cationic surfactants such as higher amine halides and quaternary ammonium salts, as well as nonionic surfactants such as polyethylene glycol alkyl ether polyethylene glycol fatty acid esters and fatty acid monoglycerides, and amphoteric surfactants such as amino acids. Addition It may be desirable for that.

In order to extend the life of the activation treatment solution, an inorganic metal ion sealing agent such as sodium tripolyphosphate, sodium tetrapolyphosphate, sodium hexametaphosphate, citric acid, gluconic acid, tartaric acid and salts thereof, EDTA At least one kind of an organic metal ion sealing agent such as a total of 5 wt% or less may be added.

The magnet is immersed in the above solution at a temperature in the range of 10 to 60 ° C. to perform an activation process.

[Plating Step] The plating of the first layer of the first layer is preferably electroplating because the plating applied to the second layer is electroplating.
When examined under the conditions of having a heat resistance of 0 ° C. or higher and a high cathode efficiency with little gas generation during plating that causes pinholes, among various plating solutions, copper pyrophosphate plating is most preferable. The result was obtained.

However, in the case of copper pyrophosphate plating, a known document “Metal Surface Technology Vol. 19 No. 9”
With the general bath composition described in 1968, it is not possible to completely form the coating on the R-Fe-B permanent magnet used in the present invention, or to obtain a coating having practically sufficient adhesion strength. Because it was extremely difficult, we reviewed the production method including bath composition and additives, pretreatment, etc.,
1 to 10 potassium pyrophosphate or sodium pyrophosphate
A plating pretreatment using an aqueous solution containing 20% by weight is performed.
0-300 g / l, copper pyrophosphate 10-30 g / l, potassium citrate or sodium citrate 10-30
g / l, ammonia is 0.1-1 ml / l, and it is extremely effective to use an alkaline plating solution having a P ratio (P ₂ O ₇ / Cu) in the range of 14-28. Was.

In this case, the pyrophosphate soaking, which is a pretreatment, depends on the state of the magnet surface, but the liquid temperature is 20 ° C. to 6 ° C.
This is performed at 0 ° C. for about 10 seconds to 3 minutes.

Next, using the plating solution described above,
-12, 20-60 ° C., while performing air stirring or mechanical stirring using a screw-type stirring rod, the cathode current density 0.5-
Plating is preferably performed using copper at 3.0 A / dm ² and the anode.

Second-layer plating The first-layer coating is electroplated using the above-mentioned plating solution to form a coating phase having substantially no voids, and then the metal coating containing the voids is subjected to room temperature to 400 ° C. Electroplating is performed to a thickness of about 3 to 10 μm so as to withstand a thermal shock in a temperature range of the order.

The film containing the pores is formed by reducing the metal ion concentration in the vicinity of the magnet base to 20 to 70% of the normal concentration, lowering the plating bath temperature, stopping stirring of the bath by air blowing or the like, and removing the plating solution. This is obtained by creating a state in which polarization is likely to occur by, for example, worsening the circulation of magnets only in the vicinity of the magnet, and making the deposition of the coating partially different.

However, since excessive polarization generates hydrogen gas which may adversely affect the R—Fe—B permanent magnet, the current density during plating is preferably set at 0.5%.
Note, such as in the range of A / dm ² ~3.0A / dm ² is also required.

In this case, as the electroplating solution for forming the second layer film, copper pyrophosphate plating solution, especially potassium pyrophosphate or sodium pyrophosphate is 200 to 450 g / l,
It is preferable to use a plating solution containing 60 to 100 g / l of copper pyrophosphate, 40 to 80 g / l of potassium citrate or sodium citrate, and 0.5 to 5 ml / l of ammonia.

Using this plating solution, preferably a pH of 8 to
12. The plating current temperature is from 20 to 60 ° C., and the cathode current density is from 0.5 to 3.0 A / dm ² , preferably from 0.5 to 3.0 A, under mild stirring such as weak air stirring or thermal convection stirring using a heater.
In the range of 1.8 A / dm ² , it is preferable to perform plating using copper as an anode.

Third-layer plating After depositing a film containing such voids, if the film is to be further enhanced in function, the above-mentioned nickel plating, nickel alloy plating, or By performing composite nickel plating, a thickness of 2 to 10 μm can be formed.

More specifically, when a magnet protected by two layers of electroplated metal as described above is used in a particularly clean environment, an electroplated metal film such as electronickel plating may be applied thereon.

When further abrasion resistance is required, an electric nickel phosphorous plating, an electric nickel SiC plating, or the like may be applied to the upper layer of the magnet having the two-layer electroplated metal protection.

In addition to the above, when a more inexpensive and higher corrosion resistance is required in addition to the above, electric nickel zinc plating or the like may be applied.

[Post-treatment] The post-treatment is performed to remove metal salts and other impurities attached in the plating step. Generally, removal is performed by washing by immersing in pure water or spraying with pure water. Then, the whole is dried with warm air.

[0046]

The present invention will now be described in detail with reference to Examples, but it should not be construed that the present invention is limited thereto.

[Examples and Comparative Examples] Nd 32 wt%, B 1.2 wt%, Fe 59.
An ingot having a composition of 8% by weight and 7% by weight of Co was prepared. This was coarsely pulverized with a jaw crusher, and further finely pulverized with a jet mill using nitrogen gas to have an average particle size of 3.5 μm.
m was obtained. Then, this fine powder was filled in a mold to which a magnetic field of 10 kOe was applied, and molded at a pressure of 1.0 t / cm ² . Next, sintering was performed at 1100 ° C. for 2 hours in a vacuum, and aging treatment was further performed at 550 ° C. for 1 hour to obtain a permanent magnet.

From the obtained permanent magnet, a magnet piece having a length of 20 mm × a width of 5 mm × a thickness of 4 mm was cut out and plated according to the following conditions. In Example 1, copper plating having a film thickness of 0.5 μm having substantially no pores, copper plating having a film thickness of 5 μm having pores, and a film thickness of 3 μm having substantially no pores
m, nickel plating having a film thickness of 0.5 μm with substantially no pores in Example 2, copper plating having a film thickness of 6 μm with pores in Example 2, and a film thickness having substantially no pores in Example 3. Copper plating of 0.5 μm, copper plating with a pore thickness of 5 μm, coating thickness of substantially void-free coating of 4 μm
A nickel-phosphorous-plated product was prepared.

Further, in Comparative Example 1, a matte nickel plating having a coating thickness of 9 μm substantially having no pores was used, and in Comparative Example 2, a matte nickel plating having a coating thickness of 4 to 5 μm having substantially no pores was used. Plated.

Table 1 shows the results obtained by observing the cross sections of these films and examining the types and thicknesses of the films and the number of pores in the films in Examples and Comparative Examples.

Each of the five samples thus prepared was placed in an electric furnace for 35 times.
After being heated and maintained at 0 ° C. × 30 min, it was immediately left on a refractory brick at about 25 ° C. to perform a thermal shock test.
c) A thermal degradation test result obtained by measuring a decrease rate (%), a film adhesion test result at a humidity of 100%, a pressure of 0.2 MPa, 120 ° C. for 48 hours, and an environmental test at a temperature of 80 ° C. and a humidity of 90% Table 2 collectively shows the results of the corrosion resistance test according to Example 1, and a cross-sectional photograph of the sample of Example 2 is shown in FIG.

The pretreatment, plating,
The method of post-processing is shown.

Example 1 Rust removal: centrifugal barrel polishing 10 minutes Alkaline degreasing: sodium hydroxide 30 g / l sodium carbonate 20 g / l sodium orthosilicate 50 g / l surfactant 2 g / l bath temperature 40 ° C. immersion time 10 min Removal of active substance: nitric acid 3 wt% Bath temperature 40 ° C immersion time 1 min Activation: potassium pyrophosphate 10 wt% bath temperature 40 ° C immersion time 1 min Plating 1: copper pyrophosphate trihydrate 30 g / l potassium pyrophosphate 280 g / l potassium citrate Monohydrate 30 g / l Ammonia 0.5 ml / l pH 10-11 P ratio 15 Bath temperature 40 ° C. Current density 0.7 A / dm ² stirring Air stirring Plating 2: Copper pyrophosphate trihydrate 60 g / l potassium pyrophosphate 210 g / L Potassium citrate monohydrate 40g / l Ammonia 1ml / l Bath temperature 40 ° C. Stirring Heat convection stirring Current density 1.0 A / dm ² Plating 3: Nickel sulfate hexahydrate 300 g / l Nickel chloride hexahydrate 40 g / l Boric acid 40 g / l pH 3-4 Temperature 60 ° C. Current density 1.5 A / Dm ² stirring Air stirring Post-treatment: pure water washing 1 min Temperature 35 ° C. Hot air drying 10 min

Example 2 Rust removal: centrifugal barrel polishing 10 minutes Alkaline degreasing: sodium hydroxide 30 g / l sodium carbonate 20 g / l sodium orthosilicate 50 g / l surfactant 2 g / l bath temperature 40 ° C. immersion time 10 min Removal of active substances: nitric acid 3 wt% bath temperature 40 ° C. immersion time 1 min activation: sodium pyrophosphate 10 wt% bath temperature 40 ° C. immersion time 1 min Plating 1: copper pyrophosphate trihydrate 30 g / l potassium pyrophosphate 300 g / l potassium citrate Monohydrate 30 g / l Ammonia 0.5 ml / l pH 10-11 P ratio 16 Bath temperature 40 ° C. Stirring Air stirring Current density 0.7 A / dm ² Plating 2: Copper pyrophosphate trihydrate 60 g / l Potassium pyrophosphate 210 g / L Potassium citrate monohydrate 40g / l Ammonia 1ml / l Temperature 40 ° C. Current density 1.0A / dm ² stirred convection stirring Workup: pure water cleaning 1min temperature 35 ° C. hot air drying 10min

Example 3 Rust removal: centrifugal barrel polishing 10 minutes Alkaline degreasing: sodium hydroxide 30 g / l sodium carbonate 20 g / l sodium orthosilicate 50 g / l surfactant 2 g / l bath temperature 40 ° C. immersion time 10 min Removal of active substances: nitric acid 3 wt% bath temperature 40 ° C. immersion time 1 min Activation: sodium pyrophosphate 10 wt% bath temperature 40 ° C. immersion time 1 min Plating 1: copper pyrophosphate trihydrate 25 g / l potassium pyrophosphate 300 g / l potassium citrate Monohydrate 30 g / l Ammonia 0.5 ml / l pH 10-11 P ratio 19 Bath temperature 40 ° C. Current density 0.7 A / dm ² stirring Air stirring Plating 2: Copper pyrophosphate trihydrate 70 g / l Potassium pyrophosphate 320 g / L Potassium citrate monohydrate 60g / l Ammonia 1ml / l Temperature 40 ° C. stirred convection stirring current density 1.0A / dm ² Plating 3: Nickel sulfate hexahydrate 200 g / l of nickel chloride hexahydrate 100 g / l phosphorous acid 10 g / l phosphate 50 g / l Temperature 50 ° C. Current density 1. 5A / dm ² stirring Air stirring Post-treatment: pure water washing 1min Temperature 35 ° C Hot air drying 10min

[Comparative Example 1] Rust removal: centrifugal barrel polishing 10 minutes Alkaline degreasing: sodium hydroxide 30 g / l sodium carbonate 20 g / l sodium orthosilicate 50 g / l surfactant 2 g / l bath temperature 40 ° C. immersion time 10 min Removal of active substances: nitric acid 3 wt% bath temperature 40 ° C. immersion time 1 min Plating: nickel sulfate hexahydrate 300 g / l nickel chloride hexahydrate 40 g / l boric acid 40 g / l bath temperature 50 ° C. pH 3-4 current density 1.5 A / Dm ² stirring Air stirring Post-treatment: pure water washing 1 min Temperature 35 ° C Hot air drying 10 min

[Comparative Example 2] Rust removal: centrifugal barrel polishing 10 minutes Alkaline degreasing: sodium hydroxide 30 g / l sodium carbonate 20 g / l sodium orthosilicate 50 g / l surfactant 2 g / l bath temperature 40 ° C. immersion time 10 min Removal of active substances: nitric acid 3 wt% bath temperature 40 ° C. immersion time 1 min Plating 1: nickel sulfate hexahydrate 300 g / l nickel chloride hexahydrate 40 g / l boric acid 40 g / l pH 3-4 bath temperature 50 ° C. current density 1. 5 A / dm ² stirring Air stirring Plating 2: Nickel sulfate hexahydrate 300 g / l Nickel chloride hexahydrate 40 g / l Boric acid 40 g / l Brightener 5 ml / l Bath temperature 50 ° C. Current density 1.5 A / dm ² stirring Air Stirring Post-treatment: Pure water washing 1 min Temperature 35 ° C Hot air drying 10 min

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

The R-Fe-B permanent magnet and the method of manufacturing the same according to the present invention make it possible to apply the permanent magnet even in an environment having an extreme temperature difference, and it is extremely effective as contributing to energy saving in recent years. Things.

[Brief description of the drawings]

FIG. 1 is a micrograph of a cross section of a magnet of an example.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 15/03 H01F 1/04 HF term (Reference) 4K023 AA19 BA12 CA09 4K024 AA03 AA09 AB02 AB03 AB12 AB19 BA02 BB14 CA02 GA16 5E040 AA04 BC01 BC08 CA01 HB14 NN05 5E062 AA06 CD04 CG07 5H622 AA03 CA02 DD02 QA02 QA08

Claims (7)

[Claims] An R—Fe—B having a metal film (R is S
c, at least one rare earth element containing Y) -based permanent magnet, wherein the metal film is 0.1 to 1..
A metal film having a thickness of 0 μm and having substantially no pores, and a major axis of a cross section of 0.1 to 1.5 μm
An R-Fe-B-based permanent magnet, characterized by being coated with a second plated metal film containing voids. 2. A nickel plating film, a nickel alloy plating film, and a composite nickel plating film in which composite particles are eutectoid as a third film on the second plating metal film of the R—Fe—B permanent magnet. The R-Fe-B-based permanent magnet according to claim 1, wherein at least one of the permanent magnets is coated. 3. The method according to claim 1, wherein the first and second plating metal films are
The R-Fe-B permanent magnet according to claim 1 or 2, wherein each of the R-Fe-B-based permanent magnets is a copper plating film formed by copper pyrophosphate electroplating. 4. An R—Fe—B (R is at least one of rare earth elements including Sc and Y) -based permanent magnet
A first-layer plating metal film having a thickness of 1.0 μm and having substantially no voids is coated, and the major axis of the cross-section is 0.1 μm.
A method for producing an R-Fe-B-based permanent magnet, which comprises coating a second plated metal film containing pores of up to 1.5 [mu] m. 5. The plating metal film of the second layer is coated with at least one of a nickel plating film, a nickel alloy plating film, and a composite nickel plating film in which composite particles are eutectoid. A method for producing the R-Fe-B-based permanent magnet described in the above. 6. The formation of the first-layer plated metal film,
1 to 10 potassium pyrophosphate or sodium pyrophosphate
A plating pretreatment using an aqueous solution containing 20% by weight is performed.
0-300 g / l, copper pyrophosphate 10-30 g / l, potassium citrate or sodium citrate 10-30
The R-Fe-B-based permanent magnet according to claim 4 or 5, wherein the electroless copper plating is performed using an aqueous solution containing 0.1 to 1 ml / l of ammonia and 0.1 to 1 ml / l of ammonia. Method. 7. The formation of the second plating metal film,
Potassium pyrophosphate or sodium pyrophosphate is 200 to
450 g / l, copper pyrophosphate 60-100 g / l, potassium citrate or sodium citrate 40-80 g
The R-Fe-B-based permanent magnet according to claim 4, 5 or 6, wherein the electroless copper plating is performed using an aqueous solution containing 0.5 to 5 ml / l of ammonia. Production method.