JP2001230108A - Method of manufacturing corrosion-resistant rare earth magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corrosion-resistant high-performance rare earth permanent magnet at a low cost. SOLUTION: Fine powder of one metal selected out of Al, Mg, Ca, Zn, Si, Mn and alloy thereof and an oxide of one or more elements selected out of Si, Mn, Zn, Mo, Cr, and P are compounded into a composite, the composite is formed into a corrosion-resistant film, and the film is provided on the pretreated surface of a rare earth permanent magnet of R-T-M-B (R is, at least, a rare earth element including Y, T denotes Fe of Fe and Co, and M is at least one element selected out of Ti, Nb, Al, V, Mn, Sn, Ca, Mg, Pb, Sb, Zn, Si, Zr, Cr, Ni, Cu, Ga, Mo, W, and Ta, and the contents of the elements are represented as follows: 5 wt.%<=R<=40 wt.%, 50 wt.%<=T<= 90 wt.%, 0.1 wt.%<=M<=8 wt.%, and 0.2 wt.%<=B<=80 wt.%).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a corrosion-resistant rare earth magnet having high corrosion resistance.

[0002]

2. Description of the Related Art Rare earth permanent magnets are widely used in a wide range of fields such as various electric products and computer peripherals because of their excellent magnetic properties, and are used in important electric and electronic materials. is there. Especially Nd-Fe-B
Compared with Sm-Co-based permanent magnets, Nd, which is a main element, is more abundant than Sm-based permanent magnets, and raw materials are inexpensive because Co is not used in large amounts. It is a very good permanent magnet far beyond the permanent magnet. For this reason, in recent years Nd-Fe-
The usage of B-based permanent magnets is increasing, and the applications are expanding.

[0003] Development research for improving the magnetic properties is based on Nd-F.
It has been energetically performed since the invention of the eB-based permanent magnet,
As one of them, there is a so-called two-alloy method in which two kinds of alloy powders having different compositions are mixed and sintered to produce a high-performance Nd magnet. Patent No. 2853838, Patent No. 2853
No. 839, JP-A-5-21218, JP-A-5-212
No. 19, JP-A-5-74618, JP-A-5-1828
No. 14 discloses that the composition of two types of alloys is determined in consideration of the types and characteristics of constituent phases of a magnetic substance, and by combining them, a balance having a high residual magnetic flux density, a high coercive force and a high energy product is obtained. There has been proposed a method for producing a reliable high-performance Nd magnet.

[0004] However, since the Nd-Fe-B permanent magnet contains a rare earth element and iron as main components, it has a disadvantage that it is easily oxidized in humid air in a short time. Therefore, when incorporated in a magnetic circuit, the output of the magnetic circuit decreases due to these oxidations,
There is a problem that rust contaminates around the equipment. The Nd—Fe—B-based permanent magnet produced by the two-alloy method proposed in the above-mentioned patent publication and the published patent publication has a composition containing Co, so that the corrosion resistance is improved to some extent. Is not enough.

[0005] In particular, recently, Nd-Fe-B permanent magnets have begun to be used in motors such as motors for automobiles and motors for elevators, but these must be used in a high-temperature and humid environment. In addition, it must be assumed that it will be exposed to moisture containing salt, and it is required to realize higher corrosion resistance at low cost. Further, in these motors, the magnet may be heated to 300 ° C. or higher for a short time in the manufacturing process, and in such a case, heat resistance is also required.

In order to improve the corrosion resistance of Nd-Fe-B permanent magnets, various surface treatments such as resin coating, Al ion plating, and Ni plating are applied in many cases. It is difficult to cope with these surface treatments with current technology. For example, resin coating lacks corrosion resistance and does not have heat resistance. Since a small number of pinholes are present in Ni plating, rust occurs in moisture containing salt. Ion plating generally has good heat resistance and corrosion resistance, but requires large-scale equipment,
It is difficult to achieve low cost.

The present invention has been made in view of the above circumstances, and has been made to provide a rare-earth permanent magnet that is high-performance and can withstand use under the above-mentioned severe conditions. It is an object of the present invention to provide a method for producing a corrosion-resistant high-performance rare-earth magnet in which a film having corrosion resistance and heat resistance is applied with good adhesion after pre-treatment.

[0008]

Means for Solving the Problems and Embodiments of the Invention The present inventor has proposed a high performance and corrosion resistant Nd-Fe-B.
As a result of intensive studies on the system permanent magnet, RTMB
(R is at least one kind of rare earth element including Y, T is Fe
Or Fe, Co, and M are Ti, Nb, Al, V, Mn,
Sn, Ca, Mg, Pb, Sb, Zn, Si, Zr, C
At least one element selected from the group consisting of r, Ni, Cu, Ga, Mo, W and Ta, and the content of each element is 5 wt% ≦ R ≦ 40 wt% and 50 wt% ≦ T ≦ 90 w, respectively.
t%, 0.1wt% ≦ M ≦ 8wt%, 0.2wt% ≦ B
≦ 8 wt%), in particular, the alloy 1 and R-
Fe—Co—MB (R and M are the same as above, and the content of each element is 30 wt% ≦ R ≦ 90 wt%, 0 wt%
≦ Fe ≦ 50 wt%, 5 wt% ≦ Co ≦ 70 wt%, 0
(wt% ≦ M ≦ 8 wt%, 0 wt% ≦ B ≦ 2 wt%), and after pretreatment is preferably performed on the surface of the manufactured rare earth permanent magnet, Al, Mg,
A fine powder of at least one metal selected from Ca, Zn, Si, Mn and alloys thereof, and Si, Mn, Z
It has been found that a rare-earth magnet excellent in corrosion resistance and heat resistance can be provided by providing a film formed by combining oxides of at least one element selected from n, Mo, Cr, and P with good adhesion. The present invention was completed by establishing various conditions.

That is, the present invention relates to (1) RTMB
(R is at least one kind of rare earth element including Y, T is Fe
Or Fe, Co, and M are Ti, Nb, Al, V, Mn,
Sn, Ca, Mg, Pb, Sb, Zn, Si, Zr, C
At least one element selected from the group consisting of r, Ni, Cu, Ga, Mo, W and Ta, and the content of each element is 5 wt% ≦ R ≦ 40 wt% and 50 wt% ≦ T ≦ 90 w, respectively.
t%, 0.1wt% ≦ M ≦ 8wt%, 0.2wt% ≦ B
≦ 8 wt%), after performing a pretreatment on the surface of the rare earth permanent magnet, Al, Mg, Ca, Zn, Si, Mn
And a corrosion-resistant film formed by combining at least one kind of metal fine powder selected from alloys thereof and an oxide of at least one kind of element selected from Si, Mn, Zn, Mo, Cr and P. And (2) In the method of (1), the rare-earth permanent magnet is formed of R-T-M-B (R
Is at least one of the rare earth elements containing Y, T is Fe or Fe and Co, M is Ti, Nb, Al, V, Mn, S
n, Ca, Mg, Pb, Sb, Zn, Si, Zr, C
At least one element selected from the group consisting of r, Ni, Cu, Ga, Mo, W and Ta, and the content of each element is 5 wt% ≦ R ≦ 40 wt% and 50 wt% ≦ T ≦ 90 w, respectively.
t%, 0.1wt% ≦ M ≦ 8wt%, 0.2wt% ≦ B
≦ 8 wt%) and R—Fe—Co—
MB (R and M are the same as above, and the content of each element is 30 wt% ≦ R ≦ 90 wt%, 0 wt% ≦ Fe ≦ 5
0 wt%, 5 wt% ≦ Co ≦ 70 wt%, 0 wt% ≦ M
≦ 8 wt%, 0 wt% ≦ B ≦ 2 wt%) and a method for producing a corrosion-resistant rare earth magnet, which is produced by mixing with alloy 2.

Hereinafter, the present invention will be described in detail. In manufacturing the Nd-Fe-B permanent magnet used in the present invention, R-T-M-B (R is at least one rare earth element including Y, T is Fe or Fe and Co, M is Ti,
Nb, Al, V, Mn, Sn, Ca, Mg, Pb, S
b, Zn, Si, Zr, Cr, Ni, Cu, Ga, M
at least one element selected from o, W, and Ta, and the content of each element is 5 wt% ≦ R ≦ 40 wt, respectively.
%, 50 wt% ≦ T ≦ 90 wt%, 0.1 wt% ≦ M ≦
8 wt%, 0.2 wt% ≦ B ≦ 8 wt%), rare earth permanent magnets, in particular, RTMB (R is at least one kind of rare earth element including Y, T is Fe or Fe and C
o and M are Ti, Nb, Al, V, Mn, Sn, Ca, M
g, Pb, Sb, Zn, Si, Zr, Cr, Ni, C
at least one element selected from u, Ga, Mo, W and Ta, and the content of each element is 5 wt% ≦
R ≦ 40 wt%, 50 wt% ≦ T ≦ 90 wt%, 0.1
(wt% ≦ M ≦ 8wt%, 0.2wt% ≦ B ≦ 8wt%)
And R-Fe-Co-MB (R and M are the same as above, and the content of each element is 30 wt.
% ≦ R ≦ 90 wt%, 0 wt% ≦ Fe ≦ 50 wt%, 5
wt% ≦ Co ≦ 70 wt%, 0 wt% ≦ M ≦ 8 wt%,
(0 wt% ≦ B ≦ 2 wt%) to prepare a rare-earth permanent magnet manufactured by a so-called two-alloy method.

Here, it is preferable that the alloy 1 has an R ₂ Fe ₁₄ B compound phase (R is at least one of rare earth elements including Y) as a main component and becomes a main phase of an Nd magnet after sintering. The alloy 1 is prepared by melting raw metal in a vacuum or an inert gas, preferably in an Ar atmosphere. As the raw material metal, a pure rare earth element, a rare earth alloy, pure iron, ferroboron, or an alloy thereof is used. Various impurities inevitable in industrial production, typically, C, N, O, H, P, S, etc. Shall be included. In the obtained alloy, αFe, R-rich phase, B-rich phase, etc. may remain in addition to the R ₂ Fe ₁₄ B phase. However, when producing a high-performance Nd magnet, the R ₂ Fe ₁₄ B phase in the alloy 1 was used. Therefore, a solution treatment is performed if necessary. The heat treatment may be performed at a temperature of 700 to 1200 ° C. for 1 hour or more in a vacuum or Ar atmosphere.

On the other hand, alloy 2 is made of R-Fe-Co-MB
(The content of each element is 30 wt% ≦ R ≦ 90 wt%, 0 w
t% ≦ Fe ≦ 50 wt%, 5 wt% ≦ Co ≦ 70 wt
%, 0 wt% ≦ M ≦ 8 wt%, 0 wt% ≦ B ≦ 2 wt
%) And R must be Pr, Dy or Tb.
It is preferable to use the same raw material metal as alloy 1
Dissolved in an empty or inert gas, preferably an Ar atmosphere
create. Raw metal is pure rare earth element, rare earth alloy, pure
Iron, ferroboron, pure cobalt, and alloys of these
Is used, but various impurities inevitable in industrial production,
Typically, C, N, O, H, P, S, etc. are included
I do. The alloy obtained in this composition contains R _TwoT¹ ₁₄B
Phase (T¹Is a transition metal element mainly composed of Fe and Co), R
Rich phase and RT^Two _FourL phase, RT^Two _ThreePhase, RT^Two _TwoPhase, R
_TwoT^Two ₇Phase B, RT^Two _FivePhase (T^TwoIs a transition mainly composed of Fe and Co
One or two of a transition metal element, the same transition metal and M, L
Represents B or B and M). The melting points of these phases
The gap is also R_TwoFe₁₄Since the melting point of the phase B is lower than that of the alloy 2, the alloy 2
It has a moderate viscosity at the setting temperature and does not disturb the orientation of the grains.
It becomes a liquid phase component that cleans the field. Alloy 2 oxidizes
It is a composition containing a large amount of rare earth elements, but Co is used.
This suppresses oxidation.

After separately pulverizing the alloys 1 and 2 described above, the powders are mixed at a predetermined ratio.
The pulverization is generally performed stepwise as coarse pulverization and fine pulverization, but mixing may be performed at any stage. However, it is preferable that the two alloy powders are uniformly mixed with substantially the same average particle size,
The average particle size is preferably in the range of 0.5 to 20 μm. 0.5 μm
If it is less than 0, it is liable to be oxidized and magnetic properties may be deteriorated. If it exceeds 20 μm, the sinterability may deteriorate.

The mixing ratio of the powders of alloy 1 and alloy 2 is preferably 70 to 99 wt% for alloy 1 and 1 to 30 wt% for alloy 2. If the content of the alloy 2 is less than 1 wt%, the liquid phase component is too small, the sintering density does not increase, and a sufficient coercive force may not be obtained. If the alloy 2 exceeds 30 wt%, the proportion of the nonmagnetic phase after sintering is too large, and the residual magnetic flux density may be reduced.

The mixed fine powder is formed into a predetermined shape by a forming press in a magnetic field, and then sintered. The sintering is preferably performed in a temperature range of 900 to 1,200 ° C. for 30 minutes or more in a vacuum or Ar atmosphere.

The Nd-Fe-B permanent magnet according to the present invention preferably has a concentration segregation of Pr, Dy and / or Tb around the grain boundary. This is alloy 2 of liquid phase component
This is because Pr, Tb, and Dy contained in the alloy do not completely diffuse into the main phase and exist near the grain boundaries even after sintering. This has the effect of further improving the coercive force of the magnet. I have.
Therefore, a magnet having higher magnetic characteristics can be manufactured even with the same composition.

The Nd—Fe—B permanent magnet according to the present invention has a magnetic property of 1.1 T or more in residual magnetic flux density Br, 796 kA / m or more in coercive force iHc, and a maximum energy product (B
H) max is preferably 239 kJ / m ³ or more, and further contains impurity elements inevitable in industrial production, typically C, N, O, H, P, S, etc., but the total amount is 2 wt%. It is desirable that: If it exceeds 2 wt%, the non-magnetic component in the permanent magnet increases, and the residual magnetic flux density may decrease. In addition, rare earth elements are consumed by these impurities, which may result in poor sintering and lower coercive force. The lower the total amount of impurities, the higher the residual magnetic flux density and coercive force, which is preferable.

The sintered body density of the Nd-Fe-B permanent magnet according to the present invention is desirably 7.2 g / cc or more. 7.2
If it is less than g / cc, a sufficient coercive force may not be obtained. Further, the bending strength is desirably 150 MPa or more, and the Vickers hardness is desirably 500 or more. Flexural strength less than 150 MPa,
A permanent magnet having a Vickers hardness of less than 500 may be damaged when actually used in a motor or the like.

In the present invention, a fine powder of at least one metal selected from the group consisting of Al, Mg, Ca, Zn, Si, Mn and alloys thereof is formed on the surface of the rare-earth permanent magnet, and Si, Mn, Zn, Mo. , Cr, P to form a corrosion-resistant film formed by compounding with an oxide of at least one element selected from the group consisting of:

Here, the metal fine powder is preferably a flake-like fine powder, which has an average major axis of 0.1 to 15 μm, an average thickness of 0.01 to 5 μm, and Aspect ratio (average major axis / average thickness) of 2
The above are preferred. More preferably, the average major axis is 1
10 to 10 μm, the average thickness is 0.1 to 0.3 μm,
And the aspect ratio (average major axis / average thickness) is 10 or more. If the average major axis is less than 0.1 μm, the flake-like fine powder will not be laminated in parallel with the substrate, and the adhesion may be insufficient. If the average major axis exceeds 15 μm, the flakes are lifted by the evaporated water during heating and baking,
The film may not be laminated parallel to the substrate, resulting in a film having poor adhesion. Further, from the viewpoint of the dimensional accuracy of the film, the average major axis is desirably 15 μm or less. Average thickness 0.01μm
If the average thickness exceeds 5 μm, the dispersion of the flakes in the aqueous dispersion becomes poor when the flake surface is oxidized in the flake production stage, the film becomes brittle and the corrosion resistance tends to deteriorate. It becomes worse and tends to settle, and the treatment liquid becomes unstable, and as a result, the corrosion resistance may be deteriorated. When the aspect ratio is less than 2, flakes are difficult to be laminated in parallel with the base material, and there is a possibility that poor adhesion may occur. There is no upper limit on the aspect ratio, but an excessively large one results in high cost, usually 50 or less.

In the film formed according to the present invention, the content of the metal fine powder, particularly the flake-like fine powder, is 70 wt%.
And more preferably 75% by weight or more. 7
If the content is less than 0 wt%, the amount of fine powder is too small to sufficiently cover the magnet substrate, and thus the corrosion resistance may be reduced.
The oxide of at least one element selected from Si, Mn, Zn, Mo, Cr, and P is preferably added in an amount of 30 wt% or less, more preferably 25 wt% or less (excluding 0).

In the present invention, as a method for forming the corrosion resistant film, a method in which the permanent magnet is immersed in an aqueous dispersion of the metal fine powder and the oxide or a method in which the aqueous solution is applied to the permanent magnet can be adopted. In this case, it is preferable to first perform a pretreatment on the surface of the magnet. Pretreatment is selected from acid treatment, alkali treatment, and blast treatment.
At least one type of treatment selected from (1) acid washing, water washing, ultrasonic washing, (2) alkali washing, water washing, and (3) shot blasting may be performed. The washing liquid used in (1) is at least one selected from nitric acid, hydrochloric acid, acetic acid, citric acid, formic acid, sulfuric acid, hydrofluoric acid, permanganic acid, oxalic acid, hydroxyacetic acid, and phosphoric acid in total. A rare-earth magnet is immersed in an aqueous solution containing 1 to 20 wt% at a temperature not lower than room temperature and not higher than 80 ° C. By performing the acid cleaning, the oxide film on the surface can be removed, which has the effect of improving the adhesion of the film. (2)
The alkaline washing liquid that can be used in the above is at least one of sodium hydroxide, sodium carbonate, sodium orthosilicate, sodium metasilicate, trisodium phosphate, sodium cyanide, a chelating agent and the like in a total of 5 or more.
It is an aqueous solution containing g / L or more and 200 g / L or less. Alkali washing has the effect of removing dirt from oils and fats attached to the magnet surface, and improves the adhesion between the film and the magnet. As the blast material of (3), ordinary ceramics, glass, plastic, and the like can be used, and the treatment may be performed at a discharge pressure of ^{2 to 3} kgf / cm ² . Shot blasting can remove the oxide film on the magnet surface in a dry manner, and also has the effect of increasing the adhesion.

Subsequent to the pretreatment, a permanent magnet is immersed in an aqueous solution of a dispersion of the metal fine powder and the oxide, or the aqueous solution is applied to the permanent magnet. After immersion or application, a heat treatment is performed, and the temperature is desirably maintained at 300 ° C. or more and less than 350 ° C. for 30 minutes or more. If the temperature is lower than 300 ° C., the film formation is insufficient and the adhesion and the corrosion resistance may be deteriorated. If the temperature is 350 ° C. or higher, the underlying magnet may be damaged, which may cause deterioration of magnetic properties.

In forming the film in the present invention,
Repeated coating and heat treatment may be performed repeatedly. The film in the present invention has a structure in which metal fine powder, particularly flake-like fine powder, is bound by an amorphous oxide. It is not clear why this shows high corrosion resistance, but when the fine powder is in the form of flakes, it is considered to be substantially parallel to the substrate, cover the magnet well, and have a shielding effect. Also,
When a metal or an alloy having a potential lower than that of the permanent magnet is used as the flake-like fine powder, it is considered that these are oxidized first and have an effect of suppressing the oxidation of the underlying magnet. Further, since this film is an inorganic material, it also has a feature that its heat resistance is higher than that of an organic film.

The average thickness of the coating of the present invention thus obtained is desirably in the range of 1 to 40 μm. 1 μm
If it is less than 40 μm, the corrosion resistance may be insufficient, and if it is more than 40 μm, the adhesion may be reduced or delamination may easily occur. Further, when the coating is thick, even if the appearance is the same, the volume of the usable R-Fe-B-based permanent magnet is reduced, which is not preferable in terms of magnet use.

[0026]

The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to the following Examples.

First, a rare earth permanent magnet was manufactured by the following method. 28 weight ratio by high frequency melting in Ar atmosphere
An ingot having a composition of Nd-69.8Fe-1Co-1B-0.2Al was prepared, and was heated at 1,070 ° C. under an Ar atmosphere at 2 ° C.
Solution treatment was performed for 0 hour. This is called alloy 1. Next, also at a weight ratio of 47Nd-13Dy-18.3Fe-20.
An ingot having a composition of Co-0.5B-1Cu-0.2Al was produced by high frequency melting in an Ar atmosphere. This is called alloy 2. The alloy 1 and alloy 2 ingots were separately coarsely pulverized with a jaw crusher under a nitrogen atmosphere, and then the alloy 1 coarse powder 93 wt% and the alloy 2 coarse powder 7 wt% were weighed and transferred to a nitrogen-blended V blender. And mixed for 30 minutes. This mixed coarse powder was further pulverized with a jet mill under nitrogen gas to obtain a fine powder having an average particle size of 3 μm. This fine powder is filled in a mold to which a magnetic field of 15 kOe is applied.
Press molding was performed at a pressure of 0 t / cm ² . This molded product is A
sintering at 1,070 ° C for 2 hours in an atmosphere of
After aging at 0 ° C. for 1 hour, a permanent magnet was obtained. A magnet piece having a diameter of 21 mm and a thickness of 10 mm was cut out from the obtained permanent magnet, subjected to barrel polishing, and then subjected to ultrasonic water washing to obtain a magnet test piece.

When the magnetic properties of this magnet were measured with a BH tracer, the residual magnetic flux density Br was 14.4 T, the coercive force iHc was 1,110 kA / m, and the maximum energy product was 39.
It was 8 kJ / m ³ . When the element distribution of Dy in this magnet was examined by EPMA, Dy was found near the grain boundary of the main phase.
And the distribution of Dy was small in the center of the main phase.

The weight of various impurity elements contained in this magnet, specifically, C, N, O, H, P, S, etc., was measured by an inert gas fusion infrared absorption method, an inert gas fusion thermal conductivity measurement method. When measured using a combustion infrared absorption method or the like, the total sum was 0.1.
It was 5 wt%. The density of the sintered body was 7.55 g / cc. When the transverse rupture strength was measured by a three-point bending method according to JIS-R-1601, it was 240 MPa. It was 600 when the Vickers hardness was measured with a load of 9.807 N using a Vickers hardness meter.

Next, flake-form aluminum powder 2 wt% and flake-form zinc powder 20 wt% (both having an average major axis of 3 μm and an average thickness of 0.2 μm)
m), a dispersion aqueous solution containing 4 wt% of chromic anhydride was prepared. The surface of the magnet test piece was subjected to the pretreatment shown in Table 1, and the test piece was immersed in this aqueous dispersion solution.
Excess droplets were removed with a spin coater whose rotation speed was adjusted to a film thickness of m, and the coating was formed by heating at 330 ° C. for 30 minutes in a hot-air drying furnace. Details of the pre-processing are as follows. Acid cleaning composition: nitric acid 10% (v / v), sulfuric acid 5% (v / v) Immersion at 50 ° C. for 30 minutes Alkaline cleaning composition: sodium hydroxide 10 g / L, sodium metasilicate 3 g / L, trisodium phosphate 10 g / L, sodium carbonate 8 g / L, surfactant 2 g / L, immersion at 40 ° C. for 2 minutes using aluminum oxide of shot blast # 220, discharge pressure 2 kgf
/ Cm ²

Next, a cross-cut adhesion test was performed on the obtained film by the following method. Cross-cut adhesion test (1) According to JIS-K-5400 cross-cut test. After making a cut in a grid pattern so that 100 pieces of 1 mm square are formed on the film with a cutter knife, strongly press the cellophane tape, pull it strongly at an angle of 45 degrees and peel it off. evaluate. (2) The magnet on which the film was formed was applied at 120 ° C., 2 atm, 200
A time cooker test was performed, and after this test, a cross-cut adhesion test was performed on the magnet. Exam contents are JI
According to the SK-5400 grid test, after making a grid-shaped cut in the film with a cutter knife so that 100 squares of 1 mm were formed, the cellophane tape was strongly pressed.
The film was strongly pulled at an angle of 45 degrees and peeled off, and the adhesion was evaluated by the number of crosses remaining. Table 1 shows the results together with Comparative Example 1 in which no pretreatment was performed. It can be seen that the adhesion is further improved by performing the pretreatment.

[0032]

[Table 1]

[0033]

According to the present invention, the surface of a high performance rare earth permanent magnet is preferably subjected to a pretreatment, and then the Al, Mg,
A fine powder of at least one metal selected from Ca, Zn, Si, Mn and alloys thereof, and Si, Mn, Z
By providing a film formed by combining oxides of at least one element selected from n, Mo, Cr, and P with good adhesion, a corrosion-resistant high-performance rare earth permanent magnet can be provided at low cost. Its utility value is extremely high in industry.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K026 AA01 AA02 AA21 BA03 BA06 BA08 BB08 CA18 CA21 CA23 CA29 CA41 DA16 EA02 EA07 EA08 5E040 AA04 AA19 BC01 CA01 HB06 HB11 HB14 HB15 NN01 NN05 5E062 CC03 CG04 CF04 CE

Claims (5)

[Claims] 1. RTMB (R is at least one of rare earth elements including Y, T is Fe or Fe and Co, M is Ti, Nb, Al, V, Mn, Sn, Ca, Mg, P
b, Sb, Zn, Si, Zr, Cr, Ni, Cu, G
a, Mo, W, Ta, and at least one element selected from the group consisting of 5 wt% ≦ R ≦ 4
0 wt%, 50 wt% ≦ T ≦ 90 wt%, 0.1 wt%
≦ M ≦ 8 wt%, 0.2 wt% ≦ B ≦ 8 wt%), after performing a pretreatment on the surface of the rare earth permanent magnet,
a fine powder of at least one metal selected from the group consisting of S, Mg, Ca, Zn, Si, Mn and alloys thereof;
A method for producing a corrosion-resistant rare earth magnet, characterized by providing a corrosion-resistant film formed by compounding an oxide of at least one element selected from i, Mn, Zn, Mo, Cr, and P. 2. The rare earth permanent magnet according to claim 1,
R-T-M-B (R is at least one rare earth element including Y, T is Fe or Fe and Co, M is Ti, Nb, A
1, V, Mn, Sn, Ca, Mg, Pb, Sb, Zn,
Si, Zr, Cr, Ni, Cu, Ga, Mo, W, Ta
At least one element selected from the group consisting of: 5 wt% ≦ R ≦ 40 wt%, 50 wt%
% ≦ T ≦ 90 wt%, 0.1 wt% ≦ M ≦ 8 wt%,
0.2 wt% ≦ B ≦ 8 wt%)
R—Fe—Co—MB (R and M are the same as above, and the content of each element is 30 wt% ≦ R ≦ 90 wt%, 0
wt% ≦ Fe ≦ 50 wt%, 5 wt% ≦ Co ≦ 70 wt
%, 0 wt% ≦ M ≦ 8 wt%, 0 wt% ≦ B ≦ 2 wt
%), A method for producing a corrosion-resistant rare earth magnet, which is produced by mixing alloy 2 represented by (%). 3. The corrosion resistance according to claim 1, wherein the surface of the permanent magnet is subjected to a treatment selected from acid cleaning, alkali treatment, and blast treatment as a pretreatment, and then the corrosion resistant film is applied. Rare earth magnet manufacturing method. 4. The method for producing a corrosion-resistant rare earth magnet according to claim 1, wherein the average thickness of the corrosion-resistant coating is 1 to 40 μm. 5. The metal powder constituting the corrosion resistant film is a flake-like fine powder having a shape having an average major axis of 0.1 to 15 μm, an average thickness of 0.01 to 5 μm, and an aspect ratio (average major axis /
The method for producing a corrosion-resistant rare earth magnet according to any one of claims 1 to 4, wherein the average thickness is 2 or more, and the content of the flake-like fine powder in the coating is 70% by weight or more.