JPH0945567A - Rare earth-iron-boron permanent magnet manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the magnetic characteristics of a rare earth-Fe-B perma nent magnet deteriorated by the cutting or electroplating process by post-heat treating it after forming an anticorrosive film. SOLUTION: After forming an anticorrosive film on the surface of a sintered magnet composed of R (= one or more rare earth elements including Y) 20-45wt.%, Fe 50-80wt.%, Co 0.1-15wt.%, B 0.5-6wt.%, Cu 5wt.% or less and M (= at least one of Al, Si, Nb, Mo, V, Mn, Sn, Ni, Zn, Ti, Cr, Ta, W, Ge, Zr, Hf and Ga) 10wt.% or less, it is heat treated in an inert gas or nonoxidating atmosphere or vacuum at 400-600 deg.C to form a rare earth-iron-born permanent magnet. The anticorrosive film is a single or multilayer film composed of one or more elements selected among Zn, Cr, Ni, Cu, Sn, Pb, Cd, Ti, W, Co, Al and Ta.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention improves the deterioration of magnetic properties due to cutting or electrolytic plating by forming a corrosion resistant film on a rare earth-iron-boron permanent magnet and then performing heat treatment to improve the film and the magnet. The present invention relates to a method for producing a rare earth-iron-boron-based permanent magnet having improved adhesion to the body.

[0002]

2. Description of the Related Art In recent years, along with the market trend toward smaller and lighter electronic equipment and precision equipment, rare earth magnets have been used in many fields in permanent magnets instead of conventional alnico and ferrite magnets. . Among rare earth permanent magnets, there is an increasing demand for rare earth-iron-boron-based permanent magnets that can obtain a high energy product, and there is a tendency for higher energy products and higher coercive force to be required than ever. However, this rare earth-iron-boron-based permanent magnet has a drawback that the temperature coefficient of residual magnetic flux density is large and demagnetization occurs at high temperature because of its low Curie temperature. In addition, it has a defect that it is easily rusted because it contains a rare earth element that is easily oxidized and iron as main components. In order to overcome this low corrosion resistance, various methods of adding elements such as Co, Ga, Ni and Cr have been proposed.

[0003]

However, even a rare earth-iron-boron-based permanent magnet containing these elements cannot provide complete corrosion resistance. Therefore, when a rare earth-iron-boron-based permanent magnet having no corrosion resistant coating is incorporated into a magnetic circuit of an electronic device or the like, oxidation occurs from the surface of the magnet body and progresses inside the magnet body. As a result, the magnetic characteristics are deteriorated and the performance of electronic devices and the like is deteriorated, and oxides on the surface of the magnet body fall off, so that the peripheral devices are contaminated with the magnetic substance. For this reason, various surface treatment methods have been proposed in order to prevent oxidation of the surface of the rare earth-iron-boron-based permanent magnet body. For example, resin coating by spraying or electrodeposition coating, vacuum deposition, ion sputtering, vapor phase plating method by ion plating, Cr,
There are an electrolytic plating method and an electroless plating method for plating a metal or alloy such as Ni. Among these, in the electrolytic plating method or the electroless plating method, in order to perform degreasing or activation treatment with an alkali or an acid as a pretreatment for plating, the grain boundary phase that plays a role of coercive force from the magnet body surface portion during pretreatment is It elutes, and as a result, a layer having deteriorated magnetic characteristics is generated on the surface of the magnet body, and the magnetic characteristics of the magnet body deteriorate. In particular, a thin magnet has a problem that the rate of deterioration in magnetic characteristics is large.

Further, in order to incorporate a rare earth-iron-boron permanent magnet body into an electronic device, it is necessary to cut the entire surface of the magnet body or a required surface before coating.
At this time as well, the surface of the magnet body is roughened and a processing deterioration layer is generated to deteriorate the magnetic characteristics. When a coating is applied on the processing-deteriorated layer, coating peeling easily occurs at the processing-deteriorated layer portion, and the adhesion of the coating deteriorates. In order to improve the deterioration of magnetic properties due to such cutting work, an alloy thin film layer of a metal element such as Ti and W and a rare earth element such as Ce, La, and Nd is formed by vapor deposition such as vacuum deposition or ion sputtering. After forming by plating method, 400 to 9 in vacuum or inert atmosphere
It has been proposed to perform heat treatment at 00 ° C for 1 minute to 3 hours (Japanese Patent Laid-Open No. 62-192566). However,
Active rare earth element at 50 at. %, The corrosion resistance is poor and the cost is high. Also, the inner hole,
There is also a problem that the groove cannot be coated.
In Japanese Patent Laid-Open No. 63-211703, in order to improve the corrosion resistance, the adhesion, and the abrasion resistance, an Ni-P alloy layer is formed by electroplating or electroless plating, and then 100 to 5 is formed.
A method of performing heat treatment at a temperature of 00 ° C. for 10 minutes to several hours has been proposed, and the examples also show a method of performing heat treatment at a temperature of 150 ° C. or 180 ° C. after forming a Ni—P plating layer. However, the heat treatment at a temperature of about 200 ° C., which is generally known as a method for removing hydrogen occluded in plating as in this example, is higher than the temperature at which a liquid phase such as an R-rich phase is generated. Since it is low, it is not possible to recover the deterioration of the magnetic properties due to cutting work or to improve the adhesion between the magnet body and the plating layer. Also, 200
There is a problem that the magnetic properties are rather deteriorated by heat treatment at about ° C. In JP-A-1-139705, a noble metal layer such as Pd and Pt and a base metal layer such as Ni are laminated on the surface of the magnet body for the purpose of improving the adhesion between the oxidation resistant film and the magnet body, and the base metal layer is 400 to 700. It has been proposed to perform a diffusion heat treatment at ° C. However, in the vapor phase plating method in which a noble metal such as Pd or Pt is formed on the surface of the magnet with a film thickness of 10 to 100 A or the method of adsorbing the noble metal colloid, the noble metal layer is likely to be non-uniform and tends to be porous. Therefore, due to this, pinholes are easily generated in the base metal layer attached thereon, and the corrosion resistance is lowered. In addition, there is a problem in that the cost of precious metals is high. On the other hand, 16
As a method of reducing the irreversible demagnetization rate in a high temperature environment such as 0 ° C. and improving thermal stability, there is a method of adding a Co element or the like, which is an element that raises the Curie temperature. Also,
It is known that the addition of Co improves the corrosion resistance. However, when Co element is added, there is a problem that the heat treatment temperature range that gives the optimum coercive force is narrowed and the mass productivity is deteriorated. Therefore, the present invention improves the corrosion resistance and the temperature coefficient by adding the Co element, improves the mass productivity by adding the Cu element in order to widen the optimum heat treatment temperature range narrowed by the addition of Co, and at the same time the sintered magnet. A rare earth element that prevents the deterioration of magnetic properties due to the formation of a corrosion resistant film on the body surface and improves the adhesion between the corrosion resistant film and the sintered magnet body.
An object is to provide a method for manufacturing an iron-boron permanent magnet.

[0005]

In order to solve the above-mentioned problems, a method for manufacturing a permanent magnet according to the present invention is designed such that R (R is one or more kinds of rare earth elements including Y) is 20 to 45 wt. %,
Fe is 50 to 80 wt. %, Co 0.1 to 15 wt.
%, B is 0.5 to 6 wt. %, Cu 5 wt. % Or less on the surface of the sintered magnet body, and then 400% in an inert gas atmosphere, a non-oxidizing atmosphere or a vacuum.
The method for producing a rare earth-iron-boron-based permanent magnet characterized by heat treatment at a temperature of up to 600 ° C., or R (R is one or more of rare earth elements including Y) is 20
~ 45 wt. %, Fe 50 to 80 wt. %, Co 0.1 to 15 wt. %, B is 0.5 to 6 wt. %, Cu
Is 5 wt. % Or less and M (M is Al, Si, Nb, M
o, V, Mn, Sn, Ni, Zn, Ti, Cr, Ta,
W, Ge, Zr, Hf, and Ga) of 10 wt. % Or less, a corrosion resistant film is formed on the surface of the sintered magnet body, and then heat treatment is performed at a temperature of 400 to 600 ° C. in an inert gas atmosphere, a non-oxidizing atmosphere or a vacuum, a rare earth-iron-boron system. A method of manufacturing a permanent magnet, wherein the corrosion-resistant coating is Zn, Cr, Ni, C.
u, Sn, Pb, Cd, Ti, W, Co, Al, Ta, a single-layer film or a multi-layer film made of one or more elements, or the corrosion-resistant film is C, P, S, O, B. ,
At least one or more elements of H and Zn, C
r, Ni, Cu, Sn, Pb, Cd, Ti, W, Co,
It is preferable to use a single-layer film or a multi-layer film made of at least one or two or more elements of Al and Ta. In the present invention, the corrosion resistant film may be either a single layer film or a multilayer film. In the case of a single layer film, the thickness of the film is 10 μm or more. In the case of a multilayer film, it is preferable that the thickness of the coating in contact with the magnet body is 0.1 μm or more, and the thickness of the entire corrosion resistant coating is 10 μm or more. Further, in the present invention, in order to improve the adhesion between the magnet body and the corrosion resistant coating, it is preferable to perform pretreatment such as degreasing and activation treatment on the surface of the magnet body before forming the corrosion resistant coating.

[0006]

The present invention provides a magnetic property by cutting or electrolytic plating by forming a corrosion resistant film on a rare earth-iron-boron permanent magnet with improved temperature coefficient of residual magnetic flux density and corrosion resistance, and then performing heat treatment. Improve the deterioration of
The present invention relates to a method for producing a rare earth-iron-boron-based permanent magnet having improved adhesion between a coating film and a magnet body. That is, since the coercive force mechanism of the rare earth-iron-boron-based permanent magnet belongs to the nucleation type, the magnitude of the coercive force is the main phase R2F14 which is a bud of the reverse magnetic domain.
It is determined by the number of lattice defects and dislocations in B, or the crystal structure and amount of the grain boundary phase surrounding the main phase R2F14B which is considered to pin the buds of the reverse magnetic domain. Therefore, if cracks or strains are generated in the main phase due to cutting, or if the main phase that does not have a grain boundary phase is exposed, buds in the reverse magnetic domain are likely to occur and the domain wall becomes easy to move and the coercive force is reduced. To do. In addition, in the pretreatment with an acid or alkali which is performed at the time of coating the corrosion resistant film, the coercive force of the magnet body surface portion is lowered because the grain boundary phase of the magnet body surface portion is eluted,
As a result, the magnetic characteristics of the entire magnet body also deteriorate. Especially,
In the case of a thin magnet body, the deterioration of the magnetic characteristics due to the pretreatment of cutting or plating becomes large.

Therefore, the present invention utilizes the rare-earth-rich phase, the B-rich phase, and the like, which are excessively present in the grain boundary phase, and after the corrosion-resistant film is formed, it can be used in an inert atmosphere, a non-oxidizing atmosphere, or a vacuum of 400- Rare earths heat-treated at 600 ℃
The present invention relates to a method for manufacturing an iron-boron permanent magnet.
When the heat treatment temperature is lower than 400 ° C., a liquid phase such as a rare earth rich phase is not generated, and the effect of the present invention cannot be obtained. It is more preferable that the heat treatment temperature is 450 ° C. or higher. The present invention improves the temperature characteristics and corrosion resistance of the sintered magnet body by containing Co, and heat treatment at a temperature at which a liquid phase appears after forming a corrosion resistant film and the coercive force is improved, whereby the grain boundary is improved. Part of the rare earth-rich phase existing in the magnet is discharged to the interface between the surface of the magnet and the corrosion-resistant film, and the part of the process-deteriorated layer formed by cutting or the part of the grain boundary phase eluted by pretreatment with acid or alkali is repaired and the magnetic It is a method of manufacturing a permanent magnet that restores the characteristics. In the present invention, the thickness of the corrosion-resistant coating is set to 10 μm or more because when the thickness of the corrosion-resistant coating is less than 10 μm, pinholes are easily formed, and the rare earth-rich phase is exuded from the pinholes by heat treatment to provide sufficient corrosion resistance. Because I can't get it. Further, if the thickness exceeds 50 μm, the smoothness of the corrosion-resistant coating deteriorates, so the thickness of the corrosion-resistant coating is preferably 50 μm or less. The corrosion resistant film may be a single layer film,
It is preferable that the film is a multilayer film and the thickness of the film in contact with the magnet body is 0.1 μm or more. By forming the multilayer film, the number of pinholes penetrating from the surface of the corrosion resistant film to the surface of the magnet body is reduced, and the corrosion from the pinholes can be prevented. If the thickness of the coating in contact with the magnet body is less than 0.1 μm, the coating tends to be thin and porous, which easily causes pinholes in the coating to be applied on top of it, so that the coating in contact with the magnet body The thickness is preferably 0.1 μm or more. Corrosion resistant film is Zn, Cr, Ni, Cu, Sn,
A single-layer film or a multi-layer film made of one or more elements selected from Pb, Cd, Ti, W, Co, Al, and Ta, or the corrosion-resistant coating is at least C, P, S, O, B, and H. Zn, Cr, Ni, one or more elements,
Cu, Sn, Pb, Cd, Ti, W, Co, Al, Ta
Of these, a single-layer film or a multi-layer film composed of at least one or two or more elements is preferable. C, P, S,
O, B, and H have the effect of microcrystallizing and amorphizing the corrosion-resistant film and contribute to the improvement of corrosion resistance. However, since the plating bath of P easily damages the magnet body, C, S, O, B, and H are added. It is more preferable to use. When forming a corrosion resistant film by electrolytic plating, Ni plating, Ni-S plating, and Cu plating are preferable because they do not damage the magnet body.

The reasons for limitation of the present invention will be described below. The rare earth element R used in the permanent magnet of the present invention is 20 to 45w.
t. %, But one or two rare earth elements including Y
20 wt. If less than%, α-F
e was generated and a high coercive force could not be obtained. %, The amount of the rare earth-rich phase that is a non-magnetic phase increases, the residual magnetic flux density decreases, and a permanent magnet having excellent characteristics cannot be obtained. Therefore, R is 20 to 45 wt. % Range is preferred. B
Is an essential element in the above permanent magnet, and is 0.5 w
t. %, The rhombohedral structure becomes the main phase and a high coercive force cannot be obtained. %, The B-rich nonmagnetic phase increases and the residual magnetic flux density decreases, so that an excellent permanent magnet cannot be obtained. Therefore, B is 0.5 to 6 wt. % Range is preferred. Fe is also an essential element in the permanent magnet, and is 50 wt. If it is less than 80%, the residual magnetic flux density decreases,
wt. %, A high coercive force cannot be obtained, so that Fe is 50 to 80 wt. % Range is preferred. Co is necessary to improve temperature characteristics and corrosion resistance, and the amount of Co added is 0.1 wt. % Or less, a sufficient effect cannot be obtained,
15 wt. If it exceeds%, the coercive force will decrease. Therefore, C
The addition amount of o is 0.1 to 15 wt. % Range is preferred.
Cu is an element necessary for expanding the optimum heat treatment temperature for obtaining the optimum coercive force and improving the mass productivity, and is 5 wt.
% Or more, the residual magnetic flux density decreases, so Cu is 5 wt.
% Or less is preferable. Also, by adding Cu,
Since the optimum heat treatment temperature can be lowered, crystallization of the corrosion resistant film can be suppressed to some extent when the heat treatment is performed after the corrosion resistant film is applied, which is preferable. In order to improve the magnetic characteristics or physical characteristics of the permanent magnet body, N
i, Nb, Ta, W, Al, Ti, Zr, Si, Ga,
One or more elements of Mo, V, Sn, Cr, Mn, Zn, Ge, and Hf are added in an amount of 10 wt. %, The permanent magnet of the present invention is a sintered anisotropic permanent magnet obtained by sintering crystalline alloy powder after anisotropy by magnetic field molding, A compound having a tetragonal crystal structure having a crystal grain size in the range of 1 to 50 μm is used as a main phase, and the maximum energy product reaches 20 MGOe or more. The rare earth-iron-boron-based permanent magnet body thus obtained is subjected to pretreatment with an acid or alkaline solution such as phosphoric acid or sodium hydroxide, and then a corrosion resistant coating is subjected to electrolytic plating, electroless plating, vapor phase plating, etc. It is produced by a generally known method.
After that, heat treatment is performed at 400 to 600 ° C. in an inert atmosphere, a non-oxidizing atmosphere, or a vacuum. As a method for forming the corrosion resistant coating, electrolytic plating and electroless plating are desirable from the viewpoint of cost and uniformity of coating thickness. Further, after forming the corrosion resistant film, heat treatment can be performed to further form the corrosion resistant film. Since the corrosion resistant film is crystallized and becomes brittle by the heat treatment, the strength can be supplemented by further forming the corrosion resistant film after the heat treatment. When forming a corrosion resistant film after heat treatment, after performing pretreatment with an acid or alkaline solution such as phosphoric acid, sodium hydroxide, etc., the corrosion resistant film is generally known for electrolytic plating, electroless plating, vapor phase plating, etc. Can be manufactured by the method described above. Further, a film such as a resin coat may be formed.

[0009]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

(Example 1) Nd23.5 wt. %, Pr
7.0 wt. %, Dy 1.5 wt. %, Al 0.2w
t. %, Nb 0.6 wt. %, B1.05 wt. %, C
o 2.3 wt. %, Ga 0.1 wt. %, Cu 0.08
wt. %, And the balance Fe was used to produce a cast ingot by high-frequency melting in an inert atmosphere. After breaking this ingot to 50 mm square or less, the broken mass was inserted into a closed container and Ar gas was allowed to flow in for 20 minutes to replace with air.
After being treated with kgf / cm @ 2 of hydrogen gas for 2 hours, it was mechanically pulverized into powder having an average particle diameter of 500 .mu.m. This coarse powder was finely pulverized into a powder having an average particle diameter of 5.0 μm using a jet mill. This fine powder was filled in a molding space formed by a die and a lower punch, and pressure-molded at 2 ton / cm 2 while orienting in a magnetic field of about 10 kOe to obtain a molded body. This molded body was sintered at 1080 ° C. for 2 hours to obtain 900
Heat treatment was performed at 1 ° C. for 1 hour to produce a permanent magnet. A sample of 10 × 11 × 8 mm (magnetization direction: 8 mm) was cut out from this magnet body, and after surface polishing, pretreatment with phosphoric acid was performed and electrolytic Ni plating with an average thickness of 20 μm was performed using a Watts bath. The sample on which the Ni plating film was formed was heat-treated in an Ar gas atmosphere at 460 to 520 ° C. for 1 hour, and then the change in the irreversible demagnetization factor with respect to the magnetic characteristics and the heating temperature was measured. FIG. 1 shows changes in coercive force with respect to heat treatment temperature, and FIG. 2 shows changes in irreversible demagnetization rate with respect to heating temperature. QUAD SEVASTIA of the sample heat-treated at 480 ℃ in Table 1
The adhesion strength of the Ni plating film by NV is shown. From FIG.
In Example 1, which is an example of the present invention, the heat treatment temperature was 460 to 50.
It can be seen that a high coercive force can be stably obtained in the range of 0 ° C. Further, from FIG. 2, it can be seen that in Example 1, the reduction of the irreversible demagnetization rate at high temperature is less than that in Comparative Examples 2 and 3.

(Comparative Example 1) Nd 23.5 wt. %, Pr
7.0 wt. %, Dy 1.5 wt. %, Al 0.2w
t. %, Nb 0.6 wt. %, B1.05 wt. %, C
o 2.3 wt. %, Ga 0.1 wt. %, And the balance Fe was used to produce a cast ingot by high-frequency melting in an inert atmosphere. After breaking this ingot to less than 50 mm square, the broken mass was inserted into a closed container, Ar gas was allowed to flow in for 20 minutes to replace air, treated with 1 kgf / cm 2 hydrogen gas for 2 hours, and then mechanically crushed and averaged. Particle size is 500μ
m powder. This coarse powder was finely pulverized into a powder having an average particle diameter of 5.0 μm using a jet mill. This fine powder is filled in a molding space formed by a die and a lower punch,
While oriented in a magnetic field of kOe, pressure molding was performed at 2 ton / cm 2 to obtain a molded body. This molded body is heated to 1080 ° C,
Sintering was performed for 2 hours, and heat treatment was performed at 900 ° C. for 1 hour to produce a permanent magnet. 10x11x8 from this magnet
mm (magnetization direction: 8 mm) was cut out, and after surface polishing, pretreatment with phosphoric acid was performed and electrolytic Ni plating with an average thickness of 20 μm was performed using a Watts bath. The sample on which the Ni plating film was formed was subjected to 500 to 5 in an Ar gas atmosphere.
After heat treatment at 50 ° C. for 1 hour, changes in magnetic property and irreversible demagnetization rate with respect to heating temperature were measured. FIG. 1 shows the change in coercive force with respect to the heat treatment temperature. 520 in Table 1
The adhesion strength of the Ni plating film by QUAD SEVASTIAN V of the sample heat-treated at ℃ is shown. It can be seen from FIG. 1 that Comparative Example 1 has a large change in coercive force with respect to the heat treatment temperature.

(Comparative Example 2) Nd23.5 wt. %, Pr
7.0 wt. %, Dy 1.5 wt. %, Al 0.2w
t. %, Nb 0.6 wt. %, B1.05 wt. %, C
o 2.3 wt. %, Ga 0.1 wt. %, Cu 0.08
wt. %, And the balance Fe was used to produce a cast ingot by high-frequency melting in an inert atmosphere. After breaking this ingot to 50 mm square or less, the broken mass was inserted into a closed container and Ar gas was allowed to flow in for 20 minutes to replace with air.
After being treated with kgf / cm @ 2 of hydrogen gas for 2 hours, it was mechanically pulverized into powder having an average particle diameter of 500 .mu.m. This coarse powder was finely pulverized into a powder having an average particle diameter of 5.0 μm using a jet mill. This fine powder was filled in a molding space formed by a die and a lower punch, and pressure-molded at 2 ton / cm 2 while orienting in a magnetic field of about 10 kOe to obtain a molded body. This molded body was sintered at 1080 ° C. for 2 hours to obtain 900
C. and 480.degree. C. were heat-treated for 1 hour to produce a permanent magnet. 10x11x8mm from this magnet (magnetization direction: 8
(mm) sample was cut out and surface-polished, and then pretreated with phosphoric acid and a Watts bath was used to produce electrolytic N having an average thickness of 20 μm.
i plating was performed. FIG. 2 shows changes in the irreversible demagnetization rate with respect to the heating temperature. Table 1 shows Ni by QUAD SEVASTIAN V
The adhesion strength of the plating film is shown. It can be seen from FIG. 2 that Example 1, which is an example of the present invention, has a better irreversible demagnetization rate at high temperatures than Comparative Example 2.

[0013]

[Table 1]

(Comparative Example 3) Nd 23.5 wt. %, Pr
7.0 wt. %, Dy 1.5 wt. %, Al 0.2w
t. %, Nb 0.6 wt. %, B1.05 wt. %, C
o 2.3 wt. %, Ga 0.1 wt. %, Cu 0.08
wt. %, And the balance Fe was used to produce a cast ingot by high-frequency melting in an inert atmosphere. After breaking this ingot to 50 mm square or less, the broken mass was inserted into a closed container and Ar gas was allowed to flow in for 20 minutes to replace with air.
After being treated with kgf / cm @ 2 of hydrogen gas for 2 hours, it was mechanically pulverized into powder having an average particle diameter of 500 .mu.m. This coarse powder was finely pulverized into a powder having an average particle diameter of 5.0 μm using a jet mill. This fine powder was filled in a molding space formed by a die and a lower punch, and pressure-molded at 2 ton / cm 2 while orienting in a magnetic field of about 10 kOe to obtain a molded body. This molded body was sintered at 1080 ° C. for 2 hours to obtain 900
C. and 480.degree. C. were heat-treated for 1 hour to produce a permanent magnet. 10x11x8mm from this magnet (magnetization direction: 8
(mm) sample was cut out and surface-polished, and then pretreated with phosphoric acid and a Watts bath was used to produce electrolytic N
i plating was performed. The sample on which the Ni plating film was formed was heat-treated at 200 ° C. for 1 hour in an Ar gas atmosphere, and then the change in the irreversible demagnetization rate with respect to the heating temperature was measured. FIG. 2 shows changes in the irreversible demagnetization rate with respect to the heating temperature. As shown in FIG. 2, Comparative Example 3 in which the heat treatment was performed at 200 ° C. after forming the plated film had the same irreversible demagnetization rate as Comparative Example 2 in which the heat treatment was not performed after forming the plated film. It turns out that the effect of is not obtained.

According to the present invention, a corrosion resistant film is formed on an R-Fe-B system permanent magnet having improved temperature characteristics and corrosion resistance, and the R-Fe-B system permanent magnet is subjected to an inert atmosphere, a non-oxidizing atmosphere or a vacuum,
By heat treatment at 400 to 600 ° C., the crystal structure portion deteriorated by cutting or electrolytic plating is repaired,
It is possible to improve the deterioration of the magnetic properties and the secular change of the magnetic properties, and also to improve the adhesion between the coating film and the magnet body, and its industrial utility value is extremely high.

[Brief description of drawings]

FIG. 1 is a diagram showing a change in coercive force with respect to a heat treatment temperature after forming a plated film.

FIG. 2 is a diagram showing changes in irreversible demagnetization rate with respect to heating temperature.

Claims (7)

[Claims] 1. R (wherein R is one or more of rare earth elements including Y) is 20 to 45 wt. %, Fe 50 to
80 wt. %, Co 0.1 to 15 wt. %, B is 0.
5-6 wt. %, Cu 5 wt. % Or less, after forming a corrosion resistant film on the surface of the sintered magnet body, 400 to 600 ° C. in an inert gas atmosphere, non-oxidizing atmosphere or vacuum
A method of manufacturing a rare earth-iron-boron-based permanent magnet, characterized in that the heat treatment is performed at the temperature of. 2. R (wherein R is one or more of rare earth elements including Y) is 20 to 45 wt. %, Fe 50 to
80 wt. %, Co 0.1 to 15 wt. %, B is 0.
5-6 wt. %, Cu 5 wt. % Or less and M (M is Al, Si, Nb, Mo, V, Mn, Sn, Ni, Z
n, Ti, Cr, Ta, W, Ge, Zr, Hf, and Ga) of 10 wt. % Or less, after forming a corrosion resistant film on the surface of the sintered magnet body, 400 to 60 in an inert gas atmosphere, a non-oxidizing atmosphere or a vacuum.
Rare earth-iron-characterized by heat treatment at a temperature of 0 ° C
Method for manufacturing boron permanent magnet. 3. The corrosion resistant coating is Zn, Cr, Ni, Cu,
The method for producing a rare earth-iron-boron-based permanent magnet according to claim 1 or 2, comprising one or more elements selected from Sn, Pb, Cd, Ti, W, Co, Al, and Ta. 4. The corrosion-resistant coating comprises at least one element selected from C, P, S, O, B and H, or two or more elements, and Zn, Cr,
Ni, Cu, Sn, Pb, Cd, Ti, W, Co, A
The method for producing a rare earth-iron-boron-based permanent magnet according to claim 1 or 2, comprising at least one element or two or more elements of 1 and Ta. 5. The method for producing a rare earth-iron-boron-based permanent magnet according to claim 1, wherein the corrosion-resistant coating is a single-layer coating having a thickness of 10 μm or more. 6. The corrosion-resistant coating is a multi-layered film, the thickness of the coating in contact with the magnet body is 0.1 μm or more, and the thickness of the multi-layered film is 10 μm or more. The method for producing a rare earth-iron-boron-based permanent magnet according to 1. 7. The method for producing a rare earth-iron-boron-based permanent magnet according to claim 1, further comprising forming a corrosion resistant film after the heat treatment.