JP2001230107A - 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 at least 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 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 or 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 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. An object of the present invention is to provide a corrosion-resistant high-performance rare-earth magnet provided with a heat-resistant film at low cost.

[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 mixed with Al 2, Mg, Ca, Zn, Si, Mn and the like on the surface of the manufactured rare earth permanent magnet. To provide a film formed by combining a fine powder of at least one metal selected from alloys of the above and an oxide of at least one element selected from Si, Mn, Zn, Mo, Cr, and P. As a result, they found that a high-performance rare earth magnet excellent in corrosion resistance and heat resistance can be provided, and established various conditions to complete the present invention.

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%) 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 corrosion-resistant rare earth magnet provided with a corrosion-resistant film formed by combining an oxide of at least one element selected from i, Mn, Zn, Mo, Cr, and P;
And (2) in the corrosion resistant rare earth magnet of (1),
The rare earth permanent magnet is formed of 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,
Pb, 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%
Alloy 1 represented by ≦ M ≦ 8 wt%, 0.2 wt% ≦ B ≦ 8 wt%, and R—Fe—Co—MB (R and M are the same as above, and the content of each element) Is 30wt% ≦ R
≦ 90 wt%, 0 wt% ≦ Fe ≦ 50 wt%, 5 wt%
≦ Co ≦ 70 wt%, 0 wt% ≦ M ≦ 8 wt%, 0 wt
% ≦ B ≦ 2 wt%) to provide a corrosion-resistant rare-earth magnet manufactured.

Hereinafter, the present invention will be described in detail. In the corrosion-resistant rare earth magnet according to the present invention, the permanent magnet used is R-T-M-B (R is at least one rare earth element including Y, T is Fe or Fe and Co, and M is Ti, N
b, Al, V, Mn, Sn, Ca, Mg, Pb, Sb,
Zn, Si, Zr, Cr, Ni, Cu, Ga, Mo,
At least one element selected from W and Ta,
The content of each element is 5 wt% ≦ R ≦ 40 wt%,
50wt% ≦ T ≦ 90wt%, 0.1wt% ≦ M ≦ 8w
t%, 0.2 wt% ≦ B ≦ 8 wt%) Rare earth permanent magnets, particularly RTMB (R is at least one of rare earth elements including Y, T is Fe or Fe and Co, M
Are 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%
Alloy 1 represented by ≦ M ≦ 8 wt%, 0.2 wt% ≦ B ≦ 8 wt%, and R—Fe—Co—MB (R and M are the same as above, and the content of each element) Is 30wt% ≦ R
≦ 90 wt%, 0 wt% ≦ Fe ≦ 50 wt%, 5 wt%
≦ Co ≦ 70 wt%, 0 wt% ≦ M ≦ 8 wt%, 0 wt
% ≦ B ≦ 2 wt%) and is 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^TwoTwo phases,
R_TwoT^Two ₇Phase B, RT^Two _FivePhase (T^TwoIs 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 are
Both are R_TwoFe₁₄Since the melting point of the phase B is lower than that of the alloy 2, the alloy 2
Has an appropriate viscosity at the sintering temperature and does not disturb the grain orientation
It becomes a liquid phase component for cleaning the grain boundaries. Alloy 2 is oxidized
It is a composition that contains a large amount of rare earth elements,
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 contains impurity elements inevitable in industrial production, typically C, N, O, H, P, S, etc., but the total is 2 wt. % Is desirable. 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, the method of forming the corrosion-resistant coating may be a method of immersing the permanent magnet in an aqueous dispersion of the metal fine powder and the oxide, or applying the aqueous solution 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. Also, 35
If the temperature is set to 0 ° 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 preferably 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.

[0025]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

First, a rare earth permanent magnet was manufactured by the following method. 28Nd-6 in weight ratio by high frequency melting of permanent magnet Ar atmosphere
An ingot having a composition of 9.8Fe-1Co-1B-0.2Al was prepared and subjected to a solution treatment at 1,070 ° C. for 20 hours in an Ar atmosphere. This is called alloy 1. Next, also in a weight ratio of 47Nd-13Dy-18.3Fe-20Co-
An ingot having a composition of 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 is further pulverized with a jet mill under nitrogen gas,
A fine powder having an average particle size of 3 μm was obtained. This fine powder is
The mold filled with the kOe magnetic field is filled, and 1.0 t / c
Press molding was performed at a pressure of m ² . This molded body was sintered at 1,070 ° C. for 2 hours in an Ar atmosphere, and further sintered at 530 ° C. for 1 hour.
Time-aging treatment was performed to obtain a permanent magnet. 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, as shown in FIG. 1, there was a large distribution of Dy near the grain boundaries of the main phase, and D
The distribution of y was small (1 is a rare earth-rich phase, 2 is a main phase (Dy-rich portion), and 3 is a main phase (Dy-low portion) in the figure).

The weight of various impurity elements contained in the 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, a film was formed on the magnet (test piece) by the following method. That is, a dispersion aqueous solution containing aluminum flakes, zinc flake powder, and chromic anhydride was prepared as a treatment liquid for forming a film. After the test piece is immersed in the aqueous dispersion, the remaining drops are removed by a spin coater whose rotation speed is adjusted to a predetermined film thickness, and then heated at 330 ° C. for 30 minutes in a hot-air drying furnace to obtain a treatment solution. A film was formed and subjected to a performance test. The performance test method is as follows. (1) Cross-cut adhesion test 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) Salt spray test (according to JIS-Z-2371) 5% salt solution is continuously sprayed at 35 ° C. and evaluated by the time until brown rust is generated.

Hereinafter, a specific example will be described. [Example 1, Comparative Examples 1 and 2] The processing liquid contained 2 wt% of flake aluminum powder and 20 wt flake zinc powder.
% (Both average major axis 3 μm, average thickness 0.2 μm) and chromic anhydride 4 wt% were used. The film thickness is 1
The thickness was set to 0 μm. For comparison, a sample in which the test piece was Ni-plated and resin-coated so that the film thickness was adjusted to 10 μm was also prepared, and a salt spray test was performed. Also, 35
The appearance change of the film after heating at 0 ° C. for 4 hours was visually examined. Table 1 also shows these results. It can be seen that the permanent magnet of the present invention (Example 1) has both corrosion resistance and heat resistance as compared with the permanent magnets subjected to other surface treatments (Comparative Examples 1 and 2).

[0031]

[Table 1]

[Examples 2 to 6] Here, samples having different film thicknesses were prepared and subjected to a grid adhesion test and a salt spray test. The same treatment liquid as that used in Example 1 was used. From this, if the film thickness is too thin, the corrosion resistance decreases,
If it is too thick, the adhesion will decrease.

[0033]

[Table 2]

[Examples 7 to 9] Here, samples in which the content of the flake-like fine powder in the film was changed were prepared, and the salt spray test and the grid adhesion test were performed. The treatment liquid contained flaky aluminum powder and flaky zinc powder (both having an average major axis of 3 μm and an average thickness of 0.2 μm).
10% mixed powder and chromic anhydride 4wt%
Was used. The weight ratio of the mixed powder in the treatment liquid was adjusted so that the content of the flake-like fine powder in the film was as shown in Table 3 and the remainder was chromic anhydride. The film thickness was adjusted to 10 μm. Thus, if the content of the flake-like fine powder in the coating is too small, the corrosion resistance is reduced.

[0035]

[Table 3]

[Examples 10 to 22] Here, a cross-cut adhesion test and a salt spray test were performed by changing the shape of the flake-like fine powder used. The processing liquid used contained 2 wt% of flake aluminum powder, 20 wt% of flake zinc powder and 4 wt% of chromic anhydride. The film thickness was set to 10 μm. If the average major axis is too short or too long, the adhesion will decrease. Also, if the average thickness is too small or too large, the corrosion resistance is reduced. Further, if the aspect ratio is too small, the adhesiveness is reduced.

[0037]

[Table 4]

[0038]

According to 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 a high performance rare earth permanent magnet. , Mn, Zn, Mo, Cr, P, by providing a coating formed by combining oxides of at least one or more elements, it is possible to provide a corrosion-resistant high-performance rare earth permanent magnet at low cost, Its utility value is extremely high in industry.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating element distribution in a permanent magnet used in an example.

[Explanation of symbols]

 1 Rare earth rich phase 2 Main phase (Dy rich part) 3 Main phase (Dy low part)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C23C 30/00 H01F 1/08 B H01F 1/08 1/04 HF term (Reference) 4K018 AA11 AA27 AB01 AC01 BA07 BA08 BA10 BA20 BB01 BB04 BC12 BD09 DA11 FA23 KA45 4K044 AA02 AB08 BA01 BA04 BA10 BA12 BA14 BA15 BA17 BB01 BB11 BC02 BC11 CA29 CA53 CA62 5E040 AA04 AA19 BC01 BD01 CA01 HB14 HB17 NN01 NN05 NN06

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%), Al, Mg, Ca, Z
fine powder of at least one metal selected from n, Si, Mn and alloys thereof, and Si, Mn, Zn, M
A corrosion-resistant rare-earth magnet provided with a corrosion-resistant coating formed by compounding with an oxide of at least one element selected from o, 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
%) Is a corrosion-resistant rare-earth magnet manufactured by mixing alloy 2 indicated by%). 3. The corrosion-resistant rare-earth magnet according to claim 1, wherein the metal structure of the rare-earth permanent magnet has a concentration segregation of Pr, Dy and / or Tb around a crystal grain boundary. 4. The corrosion-resistant rare earth magnet according to claim 1, wherein the corrosion-resistant coating has an average thickness of 1 to 40 μm. 5. The fine 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,
The average thickness is 0.01 to 5 μm, the aspect ratio (average major axis / average thickness) is 2 or more, and the content of the flake-like fine powder in the coating is 70 wt% or more. 5. The corrosion-resistant rare earth magnet according to any one of 4.