JP2002285276A - R-t-b-c based sintered magnet and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance R-T-B-C based sintered magnet (wherein R is at least one rare earth element; and T is Fe, or Fe and Co), and a production method therefor. SOLUTION: An R-T-B-C based alloy having the main componential composition of, by weight, 28 to 33% R (wherein R is at least one rare earth element) and 0.9 to 1.1% B+C (wherein the content of B is 0.6 to 0.9%, and the content of C is 0.15 to 0.3) and the balance T (wherein T is Fe, or Fe and Co) and having a main phase consisting of an R2 T14 (B, C) phase is pulverized. The obtained fine powder is recovered into a nonoxidizing solution consisting of oil such as mineral oil and at least one kind of lubricant selected from the monovalent alcohol ester of a polybasic acid, the fatty acid ester of polyhydric alcohol, and their derivatives, and is then subjected to forming, degreasing, sintering, and heat treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an RTBC-based alloy (where R is at least one rare earth element,
Is Fe, or Fe and Co) and a method for manufacturing the same.

[0002]

BACKGROUND OF THE INVENTION Nd-Fe-B based sintered magnet, coarsely crushed Nd-Fe-B based alloy having a predetermined composition, then finely pulverized in an inert gas such as N _2, the resulting average particle It is produced by molding a fine powder having a diameter of 1 to 10 μm in a magnetic field, sintering and heat-treating it, and is widely used in various magnet applied product fields.

In order to enhance the magnetic properties of the Nd—Fe—B sintered magnet, it is generally said that the content of C, which is an unavoidable impurity element, should be as low as possible. Patent No. 273133
No. 7 discloses that a raw material powder for a Nd-Fe-B-based sintered magnet is mixed with a mineral oil or a synthetic oil to form a slurry, then wet-molded, and the obtained molded body is deoiled and sintered. Discloses a method for producing a high-performance Nd-Fe-B sintered magnet to be subjected to heat treatment. According to this method, the sinterability is improved while the oxygen content is significantly reduced as compared with the conventional method, and Nd- having a high residual magnetic flux density Br, a high maximum energy product (BH) max, and a high intrinsic coercive force iHc is obtained. An Fe-B based sintered magnet can be manufactured. These high magnetic properties are obtained by performing a de-oiling (de-C) treatment before sintering so that the oil does not remain in the compact as much as possible, and the Cd of the finally obtained Nd-Fe-B-based sintered magnet is reduced. This has been achieved by reducing the content to below 0.1% by weight.

JP-A-9-17677 discloses R (where R is at least one kind of rare earth element including Y)
18 at%, B + C = 6 to 10 at% (B: 2 to 6 at%, C: 4 to 8 at%), balance Fe (1 part of Fe is one or two of Co and Ni) The alloy melt consisting of unavoidable impurities) was cast into a thin plate having a thickness of 0.03 to 10 mm by a strip casting method and cast into a slab having a structure in which the R-rich phase was finely separated to 10 μm or less. 0.02 to 5.0% by weight of liquid lubricant or solid lubricant in coarsely pulverized powder having an average particle size of 10 to 500 μm obtained by coarsely pulverizing a slab
Was added and mixed and pulverized, resulting filled with fine powder having an average particle size of 1~10μm the packing density 1.4~3.5Mg / m ³ in a mold, momentarily 795.8kA / m (10kOe) or more pulse It discloses a method of producing an R-Fe-BC-based permanent magnet material having excellent corrosion resistance by performing orientation, applying a magnetic field, forming, sintering, and aging. However, the composition of this permanent magnet material differs from that of the sintered magnet of the present invention in that the C content is as high as 4 to 8 atomic%. A specific example is described in
The permanent magnet of composition 1 in Table 1 of Japanese Patent No. 17677 has Nd: 1.
2.8 atomic%, Dy: 1.5 atomic%, Co: 10 atomic%, B: 3.
2 at%, C: 4.4 at%, and Fe: 68.1 at% (N
d: 28.2% by weight, Dy: 3.7% by weight, Co: 9.0% by weight,
B: 0.5% by weight, C: 0.8% by weight, and Fe: 57.9% by weight). Also, from the study of the present inventors,
_{R 2 T 1 4 (B,} C) the main phase is easily oxidized, with R ₂ T ₁₄ by oxidation (B, C) main phase ratio is reduced, stable 350.1kJ / m ³ (44MGOe) or more at room temperature (BH) ma
It was found that iHc of x and 1.1 MA / m (14 kOe) or more could not be obtained.

[0005] Japanese Patent No. 2739502 discloses R-Fe-B-
In a C-based alloy magnet (where R is at least one rare earth element including Y), each of the magnetic crystal grains of the alloy is covered with an oxidation-resistant protective film. It discloses an excellent oxidation resistance containing substantially all of the alloying elements constituting the magnetic crystal grains and containing 0.1 to 16 atomic% of C. However, as compared with the sintered magnet of the present invention, the R-Fe-BC-based alloy magnets of the embodiments of this publication have a high R-low B-high C composition or a low R-low B-
It has a high C composition. For specific examples, see Patent No. 2739.
No. 502, the magnet composition of Example 1 is Nd: 18 atomic%, F
e: 71 at%, B: 1 at%, and C: 10 at% (N
d: 38.8% by weight, Fe: 59.3% by weight, B: 0.1% by weight,
And C: 1.8 wt%), and the magnet composition of Example 11 was Nd: 10 at%, Fe: 79 at%, B: 1 at%, and C: 10 at% (Nd: 24.1 wt%, Fe: 73.7% by weight,
B: 0.2% by weight, and C: 2.0% by weight). Furthermore, the obtained magnetic properties are very low, and from the study of the present inventors, when these compositions are selected, 350.
(BH) max of 1 kJ / m ³ (44MGOe) or more and 1.1 MA / m (14 kOe)
e) It was found that the above iHc could not be obtained.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an R-type semiconductor having a high magnetic property even if it has a high C content containing a predetermined amount of C as a main component.
An object of the present invention is to provide a TBC based sintered magnet (where R is at least one kind of rare earth element and T is Fe, or Fe and Co) and a method for producing the same.

[0007]

In order to solve the above-mentioned problems, the method for producing an RTBC sintered magnet according to the present invention is characterized in that R is expressed by weight% (where R is at least one rare earth element). ： 28
~ 33%, B + C: 0.9 ~ 1.1% (B: 0.6 ~ 0.9%, C: 0.15 ~ 0.3%), and the balance: T (T
Is a main component composition of Fe, or Fe and Co), and has an R ₂ T ₁₄ (B, C) phase as a main phase.
C-based alloy is finely pulverized in a non-oxidizing atmosphere to an average particle size of 1 to 10 μm, and the obtained fine powder is mixed with at least one oil selected from mineral oil, synthetic oil and vegetable oil, and a monohydric alcohol of polybasic acid Ester, a fatty acid ester of a polyhydric alcohol and at least one lubricant selected from a derivative thereof and recovering the slurry into a non-oxidizing liquid to form a slurry. It is characterized by deoiling, sintering and heat treatment. RTB of the present invention
In the production of a -C sintered magnet, it is necessary to add C at a stage of melting the alloy or at a stage before melting (a predetermined amount of C is previously contained in the raw material for melting). The reason for this is that R containing unavoidable impurity levels of R
After smelted R-T-B type alloy of the ₂ T ₁₄ B phase as a main phase,
For example, at the time of coarse pulverization or fine pulverization in the form of carbon black or the like, a predetermined amount of C is added, then molded in a magnetic field, sintered,
In the sintered magnet obtained by heat treatment, C added during rough pulverization or fine pulverization is hardly taken into the R ₂ T ₁₄ B main phase, and the tendency of C to be concentrated in the R-rich phase is remarkable,
This is because the effect of improving the magnetic properties by the R ₂ T ₁₄ (B, C) phase cannot be expected.

Further, the method for producing the RTBC sintered magnet of the present invention is as follows: R (where R is at least one rare earth element): 28-33% by weight, B + C: 0.9- 1.1% (B: 0.6 to 0.9%, C: 0.15 to 0.3%) and the balance: T (where T is Fe, or Fe and Co)
Is solidified by a strip casting method, and is substantially composed of an R ₂ T ₁₄ (B, C) main phase and an R-rich phase, and has an average crystal grain size in the minor axis direction of the main phase. R- having a plate thickness of 0.05 to 3 mm, which is 3 to 20 μm
Obtaining a TBC based alloy, then coarsely pulverizing the alloy, and then pulverizing it in a non-oxidizing atmosphere to an average particle size of 1 to 10 μm,
At least one oil selected from mineral oil, synthetic oil and vegetable oil, and at least one lubrication selected from monohydric alcohol esters of polybasic acids, fatty acid esters of polyhydric alcohols and derivatives thereof are obtained. It is characterized in that it is recovered in a non-oxidizing liquid consisting of an agent and turned into a slurry, then the slurry is formed, the obtained molded body is deoiled, sintered and heat-treated.

In the method for producing an RTBC sintered magnet of the present invention, at least one oil selected from mineral oil, synthetic oil and vegetable oil, a monohydric alcohol ester of a polybasic acid, and a polyhydric acid When the mixing ratio with at least one lubricant selected from fatty acid esters of alcohols and their derivatives is 99.7 to 99.99 parts by weight: 0.3 to 0.01 parts by weight, the degree of orientation of the molded article is improved, and thus Br and (BH)
max improves. If the mixing ratio is out of the specific range, the effect of improving the degree of orientation of the compact cannot be obtained, or the amount of C delivered to the grain boundary phase increases, and R forms rare earth carbides, leading to poor sintering. .

In the method for producing an RTBC-based sintered magnet of the present invention, the RT cast obtained by strip casting is used.
-Heat treatment of the BC alloy in a substantial vacuum or in an inert gas atmosphere at 800 to 1100 ° C, then coarsening and pulverizing to a fine powder with a sharp particle size distribution, and finally obtain Br-based RTBC based sintered magnet,
(BH) max and the squareness of the demagnetization curve can be improved.

The RTBC based sintered magnet of the present invention has a weight percentage of R (where R is at least one rare earth element): 28 to 33%, and B + C: 0.9 to 1.1% (provided that it is 0.9 to 1.1%). B: 0.6-
0.9%, C: 0.15 to 0.3%), and the balance: T
(Where T is Fe, or Fe and Co), and is characterized in that the main phase is an R ₂ T ₁₄ (B, C) phase. In the RTBC-based sintered magnet of the present invention, the lattice constant ratio of the R ₂ T ₁₄ (B, C) main phase: c / a.
= 1.375 to 1.385 (where c is the lattice constant in the uniaxial anisotropy direction of the tetragonal system, and a is the lattice constant of the remaining two sides)
And high Br and (BH) max can be obtained. The R of the present invention
-In a TBC-based sintered magnet, R: 28 to 33 by weight%
%, B + C: 0.9 to 1.1% (B: 0.6 to 0.9%,
C: 0.15 to 0.3%), M: 0.01 to 0.3% (where M is at least one selected from the group consisting of Cu, Al, Ga, Nb and Mn) and the balance: T (where T is F
(e and Co, Co: 0.5 to 5%) is preferable because magnetic properties and corrosion resistance can be improved.

Further, the RTBC-based sintered magnet of the present invention comprises:
R by weight (where R is at least one rare earth element): 28 to 32%, B + C: 0.9 to 1.1% (B: 0.6 to
0.9%, C: 0.15 to 0.3%), and the balance: T
(Where T is Fe, or Fe and Co), and has a lattice constant ratio of R ₂ T ₁₄ (B, C) main phase:
c / a (where c is the lattice constant in the uniaxial anisotropy direction of the tetragonal crystal and a is the lattice constant of the remaining two sides) is 1.375
1. An RTBC-based sintered magnet having an oxygen content of 0.3% by weight or less per unit weight of the RTBC-based sintered magnet. Body density 7.56Mg /
m ³ or more.

Further, the RTBC-based sintered magnet of the present invention comprises:
% By weight of R (where R is at least two kinds of rare earth elements, which essentially contains Nd and Dy, and has a Dy content of 0.3 to 15%).
%): 28-32%, B + C: 0.9-1.1% (B:
0.6 to 0.9%, C: 0.15 to 0.3%), and the balance: T (where T is Fe, or Fe and Co), and R ₂ T ₁₄ (B, C ) The lattice constant ratio of the main phase: c / a (where c is the lattice constant in the uniaxial anisotropy direction of the tetragonal system, and a is the lattice constant of the remaining two sides) is 1.37.
An RTBC-based sintered magnet having a sintering density of 5 to 1.385, wherein the amount of oxygen contained per unit weight of the rare-earth sintered magnet is 0.3% by weight or less, and the sintered body density is 7.60%. Mg / ^{m 3}
It is characterized by the above.

In the R-T-B-C sintered magnet of the present invention, the R component is suppressed from being oxidized and carbided to secure a grain boundary phase rich in the R component, and R ₂ T ₁₄ (B, C) In order to increase the main phase ratio as much as possible and thereby increase Br, (BH) max and iHc, the oxygen content is more preferably 0.2% by weight or less, even more preferably 0.18% by weight or less.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the composition of the RTBC sintered magnet of the present invention will be described below. Hereinafter, simply writing% means weight%.

The R content is preferably 28 to 33%. In order to provide good corrosion resistance and increase (BH) max, the R amount is more preferably from 28 to 32%, particularly preferably from 28 to 31%. If the R content is less than 28%, iHc that can withstand practical use cannot be obtained, and if it exceeds 33%, Br and (B
H) The decrease in max becomes remarkable. Except for the unavoidable R component,
The utility in the case of R = Nd + Dy, Nd + Dy + Pr, Nd + Pr, or Pr + Dy is high. Dy content is 0.3 to 10% to provide practical coercive force (heat resistance)
Is more preferable, and it is more preferable to make it 0.5 to 8%. Dy
If the content is less than 0.3%, the effect of improving the coercive force cannot be obtained.
If it exceeds 0%, Br and (BH) max decrease significantly.

B and C are essential elements, and the (B + C) content is preferably 0.9 to 1.1%, more preferably 0.95 to 1.1%. The B content is preferably from 0.6 to 0.9%, more preferably from 0.65 to 0.85%. The C content is preferably 0.15 to 0.3%, and 0.18 to 0.28
% Is more preferred. When the amount of B is less than 0.6%, even if the amount of C is within the above-mentioned specific content range, the formation of R ₂ Fe ₁₇ intermetallic compound is accompanied, and the Br and iHc are greatly reduced. B amount is 0.9
%, There is almost no room for C to enter the main phase, and it is concentrated as impurities in the grain boundary phase, so that Br and iHc are greatly reduced. If the C content is less than 0.15%, R ₂ T ₁₄ (B, C)
Since the phase generation amount is too small for _{R 2 T 1 4 (B,} C) not be obtained virtually magnetic characteristics improving effect by the phase, with 0.3 percent C in the grain boundary phase is concentrated, as well as lead to sintering failure The magnetic properties decrease sharply. That is, the R ₂ T ₁₄ (B, C) phase is generated as the main phase in the above specific (B + C) amount range,
Accordingly, high magnetic properties that cannot be obtained with the conventional high C content type Nd-Fe-B sintered magnet can be obtained.

At least one element M selected from the group consisting of Cu, Al, Ga, Nb and Mn is used in an amount of 0.01 to 0.3.
%, Magnetic properties and corrosion resistance can be improved. By containing Al in an amount of 0.01 to 0.3%, iHc is improved and corrosion resistance is improved. However, when the Al content is 0.
If it exceeds 3%, the decrease of Br becomes remarkable, and if it is less than 0.01%, the effect of increasing iHc and corrosion resistance cannot be obtained. More preferred Al
The content is 0.05-0.3%. By containing 0.01 to 0.3% of Ga, iHc is remarkably improved.
%, The decrease of Br becomes large, and if it is less than 0.01%, the effect of increasing iHc cannot be obtained. A more preferable Ga content is 0.1.
It is between 05 and 0.3%. Corrosion resistance and iHc are improved by containing 0.01 to 0.3% of Cu, but when the Cu content exceeds 0.3%, the decrease of Br becomes remarkable, and when the Cu content is less than 0.01%, the corrosion resistance and iHc are reduced.
The effect of increasing c cannot be obtained. A more preferred Cu content is 0.05 to 0.3%.

By containing 0.5 to 5% of Co, the corrosion resistance is improved, the Curie point is increased, and the heat resistance is improved. However, if the Co content exceeds 5%, a Fe—Co phase harmful to magnetic properties is formed, and Br and iHc are greatly reduced.
If the Co content is less than 0.5%, the effect of improving corrosion resistance and heat resistance cannot be obtained. Also, 0.5 to 5% of Co and Cu
When the content is 0.01 to 0.3%, the effect of widening the allowable range of the second heat treatment temperature at which room temperature iHc of 1.1 MA / m (14 kOe) or more can be obtained is obtained, which is particularly preferable.

The amount of oxygen unavoidably contained is preferably 0.3% or less, more preferably 0.2% or less, and particularly preferably 0.18% or less. By reducing the oxygen content to 0.3% or less, the ratio of the R ₂ T ₁₄ (B, C) main phase is increased, and the density of the sintered body can be increased to approximately the theoretical density. As a result, 350.1 kJ / m ³ ( (BH) max of 44MGOe) or more and 1.1MA / m
IHc of (14 kOe) or more can be obtained stably. The density of the sintered body is, for example, 7.Nd-Pr-TBC-based sintered magnet.
Becomes 56 mg / ^{m 3} or more, the 7.60Mg / ^{m 3} or more Nd-Dy-T-B- C sintered magnet. In addition, in order to provide good corrosion resistance and high magnetic properties, the amount of unavoidable nitrogen is reduced to 0.
Preferably it is 15% or less, more preferably 0.002 to 0.15%. When the amount of nitrogen exceeds 0.15%, the reduction of Br becomes remarkable.

The RTBC sintered magnet of the present invention is, for example,
It can be manufactured as follows. First, adjust to the prescribed composition
The RTB-C-based alloy melt that has been
By strip casting, plate thickness: 0.05-3mm
And R₂T₁₄(B, C) Main phase and fine R
An RTBC-based alloy consisting essentially of the H phase is obtained.
R in this alloy₂T₁₄(B, C) Flatness in the short axis direction of the main phase
Uniform crystal grain size is about 3 ~ 20μm, microstructure without αFe
And an RTBC based sintered magnet having high magnetic properties.
You can get stones. If necessary, remove the sheet alloy.
Heat in an active gas atmosphere at 800-1100 ° C x 0.5-10 hours
It is preferable to perform a heat treatment. By this heat treatment, fine powder
The particle size distribution of the crushed powder becomes sharp, and Br and (BH) max are increased.
Can be Note that the heat treatment condition is 800 ° C × 0.5 hour
If it is less than 1, the effect of heat treatment is not recognized, and it exceeds 1100 ° C × 10 hours
In this case, problems such as a composition shift due to oxidation occur. The thin plate
C in the RTBC alloy is taken into the main phase.
You. This is from the melting temperature of the RTBC alloy to room temperature.
R in the process until it is cooled₂T₁₄C forms stably
After passing through the temperature range from 800 ° C to 1100 ° C, C becomes R₂T₁₄Phase B
Because it is taken in. That is, R₂T₁₄Chemistry of B
R adjusted to a composition where B is slightly less than the stoichiometric composition
-When an appropriate amount of C is present in the TB alloy, ₂
T₁₄(B, C) phase is generated and expresses high magnetic properties
It is thought that. Next, the lamellar RTBC combination
Absorbs hydrogen in gold and causes it to collapse naturally, followed by dehydrogenation
After that, this is coarsened. Then it is pulverized. Fine powder
Crushing is performed by a jet mill using inert gas as a grinding medium.
For example, the oxygen concentration is less than 0.1% by volume, more preferably 0.01% by volume.
Average particle size of 1 to 10 μm in an atmosphere of inert gas of volume% or less
Finely pulverize. Fine powder obtained in this way is converted to mineral oil, synthetic oil and
At least one oil selected from oil and vegetable oils;
Monohydric alcohol esters of acids, fatty acids of polyhydric alcohols
At least selected from esters and their derivatives
Slurry recovered in non-oxidizing liquid consisting of one kind of lubricant
- Next, the slurry is molded in a magnetic field to obtain
The compact is deoiled, sintered and heat treated. Flat of said fine powder
The average particle size is preferably 1 to 10 μm, more preferably 3 to 6 μm.
New When the average particle size is less than 1 μm, the grinding efficiency is greatly reduced.
However, if it exceeds 10 μm, the decrease in iHc and Br becomes remarkable. Molding
Molding to prevent magnetic properties from deteriorating due to body oxidation
Immediately before deoiling, it is necessary to store the compact in the oil.
desirable. Rapidly raise the temperature of the compact from room temperature to the sintering temperature
Then, the internal temperature of the compact rapidly rises and remains in the compact.
Oil reacts with the rare earth elements that make up the compact
Carbides are formed and magnetic properties are degraded. As a measure against this,
Temperature 100-500 ℃, degree of vacuum 13.3Pa (10^-130 Torr)
It is desirable to perform a deoiling treatment in which heating is performed for more than one minute. Deoiling
By the treatment, the oil in the compact is sufficiently removed. In addition,
The heating temperature of oil treatment must be 1 point if it is 100-500 ℃
And two or more points may be used. 13.3Pa (10^{− 1}Torr)
Under the heating rate from room temperature to 500 ℃ below 10 ℃ / min, more
By performing a deoiling treatment at preferably 5 ° C./min or less.
Even so, deoiling can be performed efficiently. Mineral oil, synthetic oil
Or, as a vegetable oil, from the point of deoiling and moldability, fractionation point
It should be 350 ℃ or less. The kinematic viscosity at room temperature is 10 cSt or less.
And those having 5 cSt or less are more preferable.

With respect to the RTBC-based sintered magnet of the present invention,
And 2θ = 30 to 2θ / θ method using CuKα ray as a radiation source.
X-ray diffraction in the range of 50 ° shows (105) plane and (00)
6) A strong X-ray diffraction peak from the surface can be obtained. These two
Plane distance d (d obtained from the x-ray diffraction peak positions (2θ)
= X-ray wavelength / (2sine)) and the surface index are substituted into equation (1),
R ₂T₁₄Find the lattice constants a and c of the B phase (tetragonal)
Can be. 1 / d^Two= (H²+ k²) / A²+ l^Two/ c² (1)

[0023]

The present invention will be described below in detail with reference to examples.
However, the present invention is not limited by these examples.
No. (Example 1) By weight%, Nd: 23.90%, Pr: 6.60
%, B: 0.80%, C: 0.18%, Co: 2.00%, Ga: 0.1
0%, Cu: 0.10% and balance: Fe
With a thickness of about 0.3 mm and an average crystal grain size of 3 μm in the minor axis direction.
Of the strip cast alloy of
In a nitrogen gas atmosphere adjusted to about 1 ppm (volume ratio),
Milled finely. Fine powder with average particle size of 4.0μm obtained
The nitrogen gas atmosphere in the atmosphere without touching the mineral oil
(Product name: Idemitsu Super Sol PA-3, manufactured by Idemitsu Kosan Co., Ltd.)
In 0), it was collected and slurried. Average particle size is from Sympatec
Laser diffraction particle size distribution analyzer (trade name: HEROS
Rhodes). Next, a predetermined amount of powder is added to the slurry.
Methyl oleate was added and mixed with a stirrer. Sura
The composition of Lee is as follows: 70 parts by weight of the above fine powder, 29.9 parts by weight of mineral oil
Parts by weight, methyl oleate: 0.10 parts by weight. Next
Into the cavity of the compression mold and then distribute.
Directional magnetic field strength: 1.0 MA / m (13 kOe) and molding pressure: 98 MPa
(1.0ton / cm^Two15mm x 25mm)
A rectangular parallelepiped molded product of mm × 10 mm was obtained. Next, the compact
Vacuum degree 66.5Pa (5 × 10^-1Torr), 3 o'clock at 200 ° C
Heat to remove oil, then raise temperature to 1050 ° C in the same atmosphere
And then sintered at 1050 ° C for 2 hours, then cooled to room temperature
did. Next, the sintered body is heated at 900 ° C for 2 hours in an argon atmosphere.
First heat treatment of heating and then quenching to room temperature
Was. Next, heat at 500 ° C for 1 hour in an argon atmosphere.
The second heat treatment for cooling to room temperature
I got a magnet. Table 1 shows the composition analysis results of the obtained sintered magnet.
Show. The obtained sintered magnet is processed into a 10 mm square to reduce the density.
After measuring, the results of measuring the magnetic properties at room temperature (20 ° C)
It is shown in Table 2. Also, the obtained sintered magnet is processed into 7mm square,
11.9 MA / m (150 kOe) pulsed magnetic field at room temperature (20 ° C)
Was applied and magnetization was measured. Based on this measurement, Br and magnetic
The maximum value (4πI) max of the conversion is calculated, and the calculated Br / (4πI) ma
x = 97.2%. Also, for the obtained sintered magnet,
X-ray diffraction (ray source: CuKα ray) was performed in the same manner as described above. Anisotropic
The firing was performed so that the plane perpendicular to the
Set the magnets and scan 2θ = 30 ~ 50 ° by 2θ / θ method
did. The results are shown in FIG. Both are Nd ₂Fe₁₄Phase B
Only the same X-ray diffraction pattern was observed. See below
From comparison with the X-ray diffraction pattern of Comparative Example 1 (in FIG. 1),
The X-ray diffraction peak of the (006) plane of the sintered magnet of Example 1 was high.
It turns out that it has shifted to the angle side. This was added
FIG. 1 shows that C is present in the main phase.
The diffraction pattern inside is (Nd, Pr)₂(Fe, Co)
₁₄The (B, C) phase is shown. (006) plane and (105) plane
The lattice constants c, a and c / a obtained from the diffraction peak positions are
It is shown in Table 3. Further, the obtained sintered magnet is used as a permeance coefficient Pc.
= 2.0; length 8.3mm x width 7.0mm x length 5.9mm (length direction
Is processed into a rectangular parallelepiped shape with magnetization direction
And 4.1MA / m (52kOe) magnetic field in the magnetization direction of this sample
After applying magnetization, the flux in the magnetization direction at room temperature (25 ° C)
(Φ1) was measured. Then put the sample in a thermostat,
After heating at 120 ° C for 1 hour, cool to room temperature (25 ° C)
The amount of particles (Φ2) was measured. From Φ1 and Φ2, the equation
FIG. 2 shows the thermal demagnetization rate calculated by (2). From FIG.
It can be seen that the thermal demagnetization rate is very small and the heat resistance is high. (Φ1-Φ2) ÷ Φ1 × 100 (%) (2)

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

Comparative Example 1 Nd: 23.90% by weight,
Pr: 6.60%, B: 0.90%, C: 0.03%, Co: 2.00
%, Ga: 0.10%, Cu: 0.10%, and balance: A sintered magnet was prepared in the same manner as in Example 1 except that the alloy was a coarse powder having a main component composition of Fe. Table 1 shows the composition analysis results, and Table 2 shows the measurement results of the magnetic properties and the densities.
Table 3 shows the measurement results of a) and FIG. 1 shows the X-ray diffraction pattern.
FIG. 2 shows the thermal demagnetization rates. Table 2 shows that (BH) max and iHc of the sintered magnet of Comparative Example 1 were slightly lower than those of Example 1, and that the thermal demagnetization rate was inferior to Example 1 from FIG.

(Comparative Example 2) By weight%, Nd: 23.90%,
Pr: 6.60%, B: 0.80%, C: 0.03%, Co: 2.00
%, Ga: 0.10%, Cu: 0.10%, and balance: An alloy coarse powder having a main component composition of Fe was prepared in the same manner as in Example 1 to prepare a sintered magnet. Table 1 shows the composition analysis results, Table 2 shows the measurement results of the magnetic properties and the density, and Table 3 shows the measurement results of the lattice constant ratio (c / a). (Comparative Example 3) By weight%, Nd: 23.90%, Pr: 6.60
%, B: 0.45%, C: 0.50%, Co: 2.00%, Ga: 0.1
A sintered magnet was produced in the same manner as in Example 1, except that the alloy was a coarse powder having a main component composition of 0%, Cu: 0.10% and the balance: Fe. Table 1 shows the composition analysis results, Table 2 shows the measurement results of the magnetic properties and the density, and Table 3 shows the measurement results of the lattice constant ratio (c / a).
Are shown below. The sintered magnets of Comparative Examples 2 and 3 all have extremely low coercive force and are not practical. The reason for this is that in Comparative Examples 2 and 3, B had a stoichiometric composition (about
(0.90% by weight), a third phase (R ₂ Fe ₁₇ phase) other than the main phase and the R-rich phase was formed, and it was found that the magnetic properties were reduced. On the other hand, in the case of Example 1, C added at the time of dissolution compensates for the deficiency of B from the stoichiometric composition, and R ₂ (Fe, Co) ₁₄ (B,
C) It was found that a phase was formed and the magnetic properties were improved. From a related study, the high iH of the magnet of Example 1 was obtained.
c was found to be due to an increase in the anisotropic magnetic field Ha.

(Example 2) The thickness of the sheet manufactured in Example 1 was about 0.
Charge a 3mm strip cast alloy into a vacuum furnace,
After heat treatment at 1000 ° C. for 2 hours at a degree of vacuum of about 6.7 Pa (5 × 10 ⁻² Torr), the resultant was cooled to room temperature. Using this heat-treated alloy, subsequent coarsening, fine pulverization, slurrying, transverse magnetic field compression molding, deoiling, sintering and heat treatment were performed in the same manner as in Example 1 to produce a sintered magnet. The magnetic properties and densities at room temperature (20 ° C.) are as follows, and iHc and (B
H) max had improved. (BH) max: 389 kJ / m ³ (48.8 MGOe) Br: 1.42 T (14.2 kG) iHc: 1.19 MA / m (14.9 kOe) Density: 7.59 Mg / m ³

(Examples 3 and 4) A sintered magnet having the composition shown in Table 4 was finally produced in the same manner as in Example 1 except that the composition of the main components of the strip cast alloy was changed.
C) magnetic properties and density. Table 5 shows the results.

[0031]

[Table 4]

[0032]

[Table 5]

Tables 4 and 5 show that Co and Cu were used in comparison with Example 1.
With the sintered magnet of Example 4 containing no, the same magnetic properties at room temperature as in Example 1 were obtained. Also in the sintered magnet of Example 5 containing Dy 350.1kJ / m ³ (44MGOe) greater than (BH) max and 1.1 MA /
It can be seen that iHc exceeding m (14 kOe) can be obtained.

[0034]

As described above, according to the present invention, an R-T-B-C sintered magnet having high magnetic properties even with a high C-containing type containing a predetermined amount of C as a main component. (Where R is at least one rare earth element and T is Fe, or Fe and Co) and a method for producing the same. Also, when re-melting a scrap of RTB-based sintered magnet having a high C content and recycling a raw material alloy for the RTBC-based sintered magnet, the upper limit of the allowable C content is the conventional value. There is also a cost advantage that the scrap ratio in the remelt can be increased by an amount that is higher than that of the RTB-based sintered magnet.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an X-ray diffraction pattern of a sintered magnet of the present invention, in which the vertical axis indicates the X-ray intensity (arbitrary scale), and the horizontal axis indicates the diffraction angle.

FIG. 2 is a diagram showing an example of the thermal demagnetization rate of the sintered magnet of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01F 1/053 H01F 1/08 B 1/08 41/02 G 41/02 1/04 H

Claims (10)

[Claims] 1. R in weight% (where R is at least one rare earth element): 28 to 33%, B + C: 0.9 to 1.1%.
(B: 0.6 to 0.9%, C: 0.15 to 0.3%) and the balance: T (where T is Fe, or Fe and Co
Which is a main component composition of R ₂ T ₁₄ (B, C)
The RTBC-based alloy having a main phase as a main phase is finely pulverized in a non-oxidizing atmosphere to an average particle size of 1 to 10 μm, and the obtained fine powder is at least one selected from mineral oil, synthetic oil and vegetable oil. Oil in a non-oxidizing liquid composed of a monohydric alcohol ester of a polybasic acid, a fatty acid ester of a polyhydric alcohol, and at least one lubricant selected from the derivatives thereof to form a slurry, A method for producing an RTBC-based sintered magnet, comprising molding the slurry, deoiling, sintering, and heat-treating the obtained compact. 2. At least one oil selected from mineral oil, synthetic oil and vegetable oil, and at least one lubrication selected from monohydric alcohol esters of polybasic acids, fatty acid esters of polyhydric alcohols and derivatives thereof. The method for producing a sintered R-T-B-C magnet according to claim 1, wherein the mixing ratio with the agent is 99.7 to 99.99 parts by weight: 0.3 to 0.01 parts by weight. 3. In% by weight, R (where R is at least one rare earth element): 28 to 33%, B + C: 0.9 to 1.1%.
(B: 0.6 to 0.9%, C: 0.15 to 0.3%) and the balance: T (where T is Fe, or Fe and Co
) Is solidified by a strip casting method, and is substantially composed of an R ₂ T ₁₄ (B, C) main phase and an R-rich phase, and the average crystal of the main phase in the minor axis direction. Sheet thickness 0.05-3m with a particle size of 3-20μm
m of an RTBC-based alloy, and then coarsely pulverized, and then pulverized in a non-oxidizing atmosphere to an average particle size of 1 to 10 μm. And a non-oxidizing liquid comprising at least one oil selected from vegetable oils and at least one lubricant selected from monohydric alcohol esters of polybasic acids, fatty acid esters of polyhydric alcohols and derivatives thereof. And producing a slurry, and then forming the slurry, deoiling, sintering, and heat-treating the obtained molded body. 4. At least one oil selected from mineral oil, synthetic oil and vegetable oil, and at least one lubrication selected from monohydric alcohol esters of polybasic acids, fatty acid esters of polyhydric alcohols and derivatives thereof. The method for producing an RTBC-based sintered magnet according to claim 3, wherein the mixing ratio with the agent is 99.7 to 99.99 parts by weight: 0.3 to 0.01 parts by weight. 5. The RT-C alloy according to claim 3, wherein the RT-B-C-based alloy obtained by solidification by a strip casting method is heat-treated at 800 to 1100 ° C. and then coarsened.
A method for producing a BC sintered magnet. 6. R in weight% (where R is at least one rare earth element): 28 to 33%, B + C: 0.9 to 1.1%.
(B: 0.6 to 0.9%, C: 0.15 to 0.3%) and the balance: T (where T is Fe, or Fe and Co
Which is a main component composition of R ₂ T ₁₄ (B, C)
An RTBC-based sintered magnet characterized in that the main phase is a phase. 7. A lattice constant ratio of a main phase of R ₂ T ₁₄ (B, C): c / a (where c is a lattice constant in a uniaxial anisotropy direction of a tetragonal crystal, and a is The lattice constant is 1.
7. The RTBC based sintered magnet according to claim 6, wherein the ratio is from 375 to 1.385. 8. R: 28-33% by weight%, B + C: 0.9-%
1.1% (B: 0.6 to 0.9%, C: 0.15 to 0.3%), M: 0.01 to 0.3% (where M is Cu, Al, G
7. A main component composition of at least one selected from the group consisting of a, Nb, and Mn) and the balance: T (where T is Fe and Co, and Co is 0.5 to 5%). Or an RTBC-based sintered magnet according to 7. 9. R by weight (where R is at least one rare earth element): 28 to 32%, B + C: 0.9 to 1.1%.
(B: 0.6 to 0.9%, C: 0.15 to 0.3%) and the balance: T (where T is Fe, or Fe and Co
Which is a main component composition of R ₂ T ₁₄ (B, C)
R-T in which the lattice constant ratio of the main phase: c / a (where c is the lattice constant in the direction of uniaxial anisotropy of tetragonal crystal and a is the lattice constant of the remaining two sides) is 1.375 to 1.385 A BC-based sintered magnet, wherein the RTBC-based sintered magnet has an oxygen content per unit weight of 0.3% by weight or less and a sintered body density of 7.56 Mg / m 2. R- characterized by being ³ or more
TBC sintered magnet. 10. R in weight% (where R is at least two kinds of rare earth elements, which essentially contains Nd and Dy, and Dy
Content is 0.3 to 15%): 28 to 32%, B + C: 0.9 to
1.1% (B: 0.6 to 0.9%, C: 0.15 to 0.3%) and the balance: T (where T is Fe or Fe and C
o), and R ₂ T ₁₄ (B,
C) R- having a lattice constant ratio of the main phase: c / a (where c is a lattice constant in a uniaxial anisotropy direction of a tetragonal crystal and a is a lattice constant of the remaining two sides) is 1.375 to 1.385. A TBC sintered magnet, wherein the rare earth sintered magnet has an oxygen content per unit weight of 0.3% by weight or less and a sintered body density of
And characterized in that 7.60Mg / ^{m 3} or more R-T-B-C
Series sintered magnet.