JP2002124407A - Anisotropic sintered rare-earth manget and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new high-performance anisotropic sintered rare-earth magnet in which no R-rich phase substantially exists, and to provide a method of manufacturing the magnet. SOLUTION: The anisotropic sintered rare-earth magnet is composed of 5-30 mass% rear-earth element R, 0.3-5 mass% boron B, 0.01-7 mass% dopant M1 (at least one kind selected from among Ti, Zr, and Hf), 0.01-7 mass% dopant M2 (at least one kind selected from among Al, Cr, Ni, Cu, Zn, Ga, and Mn), 0.01-50 mass % Co, and the balance Fe and impurities which are inevitable from the manufacturing point of view.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to SmCo ₅ , Sm ₂
The present invention relates to a novel anisotropic rare earth magnet different from a Co ₁₇ , Nd—Fe—B sintered magnet and a method for producing the same.

[0002]

_2. Description of the Related Art Rare earth sintered magnets include SmCo ₅ and Sm _2.
There is a Co ₁₇ , Nd—Fe—B based sintered magnet. Each magnet has its own characteristics, and it is applied to the corresponding application. SmCo ₅ and Sm ₂ Co ₁₇ based sintered magnets are inferior in magnetic properties to Nd—Fe—B based sintered magnets, but have excellent thermal stability and are mainly used for high temperature applications such as motors and generators. Is done. On the other hand, Nd-Fe-B sintered magnets have excellent magnetic properties and are inexpensive, so they are currently the mainstream of rare earth magnets. Since this magnet has poor thermal stability and corrosion resistance, it is made into a product by Ni plating or the like for many uses such as hard disk drives and CDs. Nd-Fe-
Nd ₂ Fe, which has hard magnetic properties, is used for B-based sintered magnets.
Nd-rich phase in addition to _{14 B, Nd 1.1 Fe 4 B} 4 (B
Rich phase) and oxide phase (M. Sagawa et al,
Japanese Journal of Applied Physics 26, 785 (198
7)).

[0003]

Conventionally, high-performance Nd-
In order to obtain an Fe-B based sintered magnet, the amount of additives such as Dy, Al, Ga, and Cu for improving the coercive force is reduced, and the magnetic properties are improved by reducing the B-rich phase and the oxide phase. I went. However, the Nd-rich phase is composed of the main phase particles (Nd
₂ Fe ₁₄ B) has the effect of cleaning the grain boundaries and is indispensable for generating a coercive force, so that this phase cannot be eliminated. Further, in order to improve the performance of rare earth magnets, the amount of rare earth elements is reduced, and Fe,
It is necessary to increase the amount of transition metal such as Co, but this cannot be done with the current Nd-Fe-B based sintered magnet. This is because, when the amount of the transition metal is increased, the Nd-rich phase does not substantially exist, so that the grain boundary cannot be cleaned and a high coercive force cannot be obtained. Therefore, the present inventor has invented a new and high-performance anisotropic rare earth sintered magnet in which the amount of the rare earth element is reduced while the amount of the transition metal is increased, and the R-rich phase is not substantially present ( See Japanese Patent Application No. 2000-20467). However, this system magnet has the disadvantage that the coercive force is low and a high energy product cannot be obtained. Therefore, we examined various additive elements and found that Al, Cr, Ni, C
It has been found that the addition of at least one of u, Zn, Ga, and Mn is effective in improving the coercive force and the maximum energy product.

[0004]

Means for Solving the Problems In order to solve the above problems, the present invention comprises the following constitutions. (1) Composition: rare earth element R: 5 to 30 mass%, boron B: 0.3 to 5 mass%, C: 0.01 to 5 mass
s%, and additional element M ₁ (at least one of Ti, Zr, Hf): 0.01 to 7 mass%, and additional element M ₂ (A
1, at least one of Cr, Ni, Cu, Zn, Ga and Mn): 0.01 to 5 mass%, Co: 0.01 to
50 mass%, balance: an anisotropic rare earth sintered magnet composed of Fe and unavoidable impurities in production.
Rare earth element R: 5 to 30 mass%, boron B: 0.3 to
5 mass%, C: 0.01 to 5 mass%, and additional element M ₁ (at least one of Ti, Zr, Hf): 0.
01 to 7 mass%, additional element M ₂ (Al, Cr, N
i, at least one of Cu, Zn, Ga, and Mn):
0.01-5 mass%, Co: 0.01-50mas
s%, balance: alloy composed of Fe and unavoidable impurities in production, blended and melted, cast to form an ingot, pulverized the ingot, and then as a carbon C raw material, metal stearate, paraffin wax or TiC , ZrC, HfC powder at 0.01 to 5 mass%,
This is a method for producing an anisotropic rare earth magnet, which comprises forming, sintering, and heat-treating.

[0005] The conventional R-Fe-B based sintered magnet is Nd
Since the rich phase is indispensable for the generation of coercive force, 28 to 35
Rare earth elements of about mass% are required. R-Fe-
The minimum required rare earth amount of the B-based sintered magnet is determined by a balance with the oxygen amount. That is, when the oxygen content is 2000 ppm or less, a high coercive force can be obtained even when the rare earth content is 29 to 31 mass%, but when the oxygen content exceeds 10,000 ppm, the rare earth content needs to be about 35 mass%. For this reason, in order to develop the next magnet material with a high Br, it is necessary to reduce the amount of oxygen and at the same time obtain a high coercive force without an Nd-rich phase. Thus, it is considered that the amount of the R element is reduced, the amounts of Fe and Co are increased, and high saturation magnetization and Br are obtained. The present inventor has studied various compositions for obtaining a high coercive force with a composition that does not generate an R-rich phase in an R—Fe—B based sintered magnet. As a result, R-
It has been found that by adding Ti, Zr, and Hf to the (Fe, Co)-(B, C) system in combination, characteristics as a permanent magnet can be obtained even in a composition range in which the amount of the R element is small.
The phase composition of this magnet is R ₂ Fe ₁₄ B phase, (Ti, Zr,
Hf) It is composed of a rich phase, an oxide phase, FeCo, etc.
The feature is that there is no rich phase. Normal Nd-Fe-
A high coercive force could not be obtained for the B-based sintered magnet without the Nd-rich phase. In this regard, the magnet of the present invention can be said to be a magnet different from the Nd-Fe-B based sintered magnet. Japanese Patent Application 2000-204
The magnet of No. 67 has properties exceeding those of a ferrite magnet, but in order to further increase (BH) Max, improvement of the coercive force was indispensable. Therefore, various elements were examined as additive elements, and Al, Cr, Ni, Cu, Zn, G
It has been found that at least one of a and Mn is effective in improving coercive force.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a sintered anisotropic rare earth magnet according to the present invention is based on R- (Fe, Co)-(B, C)-(T
i, Zr, Hf)-(Al, Cr, N
An alloy of at least one of i, Cu, Zn, Ga, and Mn) is prepared by melting, hydrogen is absorbed and dehydrogenated, and then the alloy is pulverized by a bantam mill or the like and further finely pulverized. Fine pulverization is performed by a ball mill or a jet mill. C material is further added to the obtained fine powder,
Mix with a V blender or the like. Material C has an average particle size of 10μ
m or less graphite powder, or a C-containing compound such as metal stearate or wax. Alternatively, powders of TiC, ZrC, and HfC may be used. The fine powder is oriented by a vertical magnetic field, a horizontal magnetic field, or a pulse magnetic field, and is formed by hydraulic molding, mechanical press, or servo press. The obtained molded body is sintered at a temperature in the range of 1000 to 1200 ° C and heat-treated at a temperature in the range of 400 to 900 ° C.

(Example 1) Nd: 13, Pr: 13,
B: 1.1, Zr: 3.0, Ga: 0, 1, 2, 3,
4, Co: 10Fe: bal, Nd: 13, Pr: 1
3, B: 1.1, Zr: 3.0, Ga: 0,1,2,2
3, 4, Co: 20, Fe: bal, Pr: 26, B:
1.1, Zr: 3.0, Ga0, 1, 2, 3, 4, C
Each alloy of o: 30 and Fe: bal was produced by strip casting. After hydrogen absorbing and dehydrogenating these alloys, they were crushed by a bantam mill. Next, after finely pulverizing by a jet mill, Zn stearate was added to each fine powder at 0.06 wt% and mixed with a V-type mixer. The fine powder is subjected to transverse magnetic field molding,
Vacuum sintering was performed at 1140 ° C. FIG. 1 shows the magnetic properties of the obtained sintered body.

(Example 2) Using the same alloy as in Example 1, hydrogen absorption and dehydrogenation treatment was performed at room temperature in the same manner as in Example 1, and then crushed with a bantam mill. Next, after fine pulverization was performed by a jet mill, 0.2 wt% of C powder having an average particle diameter of 1 μm was added to each fine powder and mixed with a V-type mixer.
The fine powder is subjected to transverse magnetic field molding, and the obtained compact is subjected to 1100 to 11
Vacuum sintering was performed at 40 ° C. FIG. 2 shows the magnetic properties of the obtained sintered body. By adding 0.2 wt% of C powder, squareness is improved and (BH) max is improved.

Example 3 Composition, Nd: 13, Pr: 1
3, B: 1.1, Zr: 3.0, (Al, Mn): 0,
1, 2, Co: 20, Fe: bal, Nd: 13, P
r: 13, B: 1.1, Zr: 3.0, (Cr, N
i): Alloys of 0, 2.5, 5, Co: 20, Fe: bal were produced by strip casting. Each of these alloys was subjected to a hydrogen storage / dehydrogenation treatment and then pulverized by a bantam mill. Next, after finely pulverizing with a jet mill, 0.08 wt% of paraffin wax (melting point: 63 ° C.) was added to each fine powder. The fine powder was subjected to transverse magnetic field molding, and the obtained compact was vacuum-sintered at 1100 to 1140 ° C. FIG. 3 shows the magnetic properties of the obtained sintered body. It can be seen that the magnetic properties are improved by each additive element.

(Example 4) Composition, Nd: 13, Pr: 1
3, B: 1.1, Zr: 3.0, Cu: 0, 1, 2, 2,
3,4, Co: 10, Fe: bal, Nd: 13, P
r: 13, B: 1.1, Zr: 3.0, Cu: 0, 1,
2, 3, 4, Co: 20, Fe: bal, Pr: 26,
B: 1.1, Zr: 3.0, Cu: 0, 1, 2, 3,
4, alloys of Co: 30 and Fe: bal were produced by strip casting. After hydrogen absorbing and dehydrogenating these alloys, they were crushed by a bantam mill. Next, after finely pulverizing with a jet mill, 0.2% by weight of Zn stearate was added to each fine powder and mixed with a V-type mixer. The fine powder is subjected to transverse magnetic field molding, and the obtained compact is 1100
Vacuum sintering was performed at １1140 ° C., and the heat treatment was performed at 950 ° C. × 2 hours and cooled to 400 ° C. or less at a cooling rate of 1.0 ° C./min. FIG. 4 shows the magnetic properties of the obtained magnet.

Example 5 Composition, Nd: 10, Pr: 1
4, B: 1.0, C: 0.2, Ti: 1.6, Co: 1
0, an alloy of Fe: bal was produced by a strip casting method. After hydrogen absorbing and dehydrogenating the alloy, it was crushed by a bantam mill. Next, after finely pulverizing by a jet mill, each fine powder was made of Z having an average particle size of 20 μm.
The n powder was added in an amount of 0.1, 2 wt% and mixed with a V-type mixer. The fine powder is subjected to transverse magnetic field molding,
After vacuum sintering at 1140 ° C., a heat treatment at 700 ° C. × 2 h was performed. Table 1 shows the magnetic properties of the obtained magnet.

[0012]

[Table 1]

[0013]

According to the present invention, SmCo ₅ , Sm ₂ Co ₁₇ , Nd-F
A new anisotropic rare earth sintered magnet different from the EB based sintered magnet was obtained. The present magnet is based on the R-Fe-B system, but has no R-rich phase and is a novel magnet having a different coercive force generating mechanism. As additional elements for improving the magnetic properties of this novel magnet, Al, Cr, Ni, Cu, Zn, Ga,
Coercive force and squareness are further improved using Mn, and it is a magnet material with a wide range of applications.

[Brief description of the drawings]

FIG. 1 is a diagram showing magnetic characteristics of an anisotropic rare earth sintered magnet of the present invention.

FIG. 2 is a diagram showing the magnetic properties of the anisotropic rare earth sintered magnet of the present invention.

FIG. 3 is a diagram showing the magnetic properties of the anisotropic rare earth sintered magnet of the present invention.

FIG. 4 is a diagram showing magnetic properties of the anisotropic rare earth sintered magnet of the present invention.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 38/00 303 C22C 38/00 303D H01F 1/053 H01F 1/04 A

Claims (2)

[Claims] 1. The composition is a rare earth element R: 5 to 30 mas.
s%, boron B: 0.3 to 5 mass%, C: 0.01 to
5 mass%, additional element M ₁ (at least one of Ti, Zr, Hf): 0.01 to 7 mass%, additional element M
₂ (at least one of Al, Cr, Ni, Cu, Zn, Ga, and Mn): 0.01 to 5 mass%;
An anisotropic rare earth sintered magnet, characterized in that it is composed of 01 to 50 mass%, the balance being Fe and unavoidable impurities in production. 2. The composition has a rare earth element R of 5 to 30 mas.
s%, boron B: 0.3 to 5 mass%, C: 0.01 to
5 mass%, and additional element M ₁ (at least one of Ti, Zr, Hf): 0.01 to 7 mass%, additional element M ₂ (at least one of Al, Cr, Ni, Cu, Zn, Ga, Mn) : 0.01 to 5 mass%, Co:
0.01-50 mass%, balance: alloy composed of Fe and unavoidable impurities in production, blended, melted and cast to form an ingot, pulverized, and then metal stearate as carbon C raw material , Paraffin wax or Ti
C, ZrC, HfC powder at least one of 0.01 to
A method for producing an anisotropic rare earth magnet, comprising adding 5 mass%, followed by molding, sintering, and heat treatment.