JP3148581B2 - Method for producing R-Fe-BC-based permanent magnet material having excellent corrosion resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to R (where R contains at least one rare earth element including Y), Fe,
The present invention relates to a method for producing a raw material powder for permanent magnets containing B and C as main components, and a method for manufacturing a molten alloy containing R, Fe, B and C as main components by a strip casting method such as a single roll method or a twin roll method. A thick slab having a homogeneous structure in which the R-rich phase is finely separated is obtained, coarsely pulverized, a lubricant is added and blended, and then finely pulverized, thereby enabling efficient fine pulverization. After being subjected to a pulse magnetic field to orient and then molded and sintered, R has excellent corrosion resistance and orientation, and has excellent magnetic properties and excellent corrosion resistance.
The present invention relates to a method for producing a Fe-BC permanent magnet material.

[0002]

2. Description of the Related Art Today, a typical high performance permanent magnet R
-Fe-B based permanent magnet (JP-A-59-46008)
Has high magnetic properties in a structure having a main phase of a ternary tetragonal compound and an R-rich phase, and is used in a wide range of fields from various household electrical appliances to peripherals of large computers, and is used in various fields. R-Fe-BC permanent magnets of various compositions have been proposed to exhibit various magnet properties.

Although the R-Fe-B permanent magnet has extremely excellent magnetic properties, it has problems in corrosion resistance and temperature characteristics. A method of coating the surface of a magnet with a corrosion-resistant metal film or a resin film has been proposed (Japanese Patent Application Laid-Open Nos. 60-54406 and 60-63901). Various parts of Fe have been replaced by Co to examine compositionally (Japanese Patent Application Laid-Open No. 59-6 / 1984).
No. 4733), which was not yet sufficient.

Recently, a part of B of an R—Fe—B magnet has been changed to C
To form a boundary phase having excellent corrosion resistance, thereby improving the corrosion resistance and improving the temperature characteristics.
A C-based magnet has been proposed (Japanese Patent Application Laid-Open No. 3-82744). The R—Fe—BC system magnet has a B content of 2 at%.
It is characterized by the following facts and containing a large amount of C. That is, when part of B is replaced by C, the main phase of R ₂ Fe ₁₄ B tetragonal crystal becomes R ₂ F in which part of B is replaced by C.
e ₁₄ (B _1-x C _x ) tetragonal, but the crystal structure is the same, and the grain boundary phase changes from the R-rich phase to the R-
The R- phase changes to the Fe-C phase and a part of Fe is replaced by Co.
Fe-Co-B-C system is the main phase in the magnet _{R 2 Fe 14 R 2 (Fe} 1-x Co x) of B tetragonal same crystal structure ₁₄ (B
_1-y C _y ) becomes tetragonal, and the grain boundary phase changes to an R-rich phase (R-Fe-Co-C phase) having good corrosion resistance. However, if a large amount of C is contained in the magnet, C becomes R (Rare earth element), RC (rare earth carbide) is easily formed, and RC is generated in the raw material alloy and the sintered magnet.

[0005] In short, the R-Fe-B-C magnet is an R-Fe-B-based magnet in which R reacts with C to become R-C, and R is consumed. More R is required. Therefore, since there are many RCs that do not contribute to the magnetic properties, Br is lower than that of the R-Fe-B system, and a large amount of expensive R is required. There has been a problem that the magnetic characteristics are deteriorated and varied with the increase. Until now, R-Fe-BC-based magnets have been manufactured by pouring a molten alloy into a mold to form an ingot, and then pulverizing, pulverizing, molding, sintering, and aging the powder metallurgy method. Magnetization or the ingot or the coarse powder after grinding of the ingot was subjected to solution treatment, pulverized, and magnetized by the powder metallurgy method described above to improve corrosion resistance and temperature characteristics. -F
The magnetic properties of the e-B-C based magnet were such that (BH) max was at most about 38 MGOe. Further, the R-Fe-
The BC magnet has a problem in that the squareness of the demagnetization curve is extremely poor, and the magnet is easily demagnetized with respect to the temperature and the reverse magnetic field as compared with the R-Fe-B magnet having the same size and shape.

In order to prevent coarsening of crystal grains, α-Fe retention, and segregation, which are disadvantages of the R-Fe-B alloy powder by the ingot pulverization method, a molten R-Fe-B alloy is used. By a roll method, a slab having a thickness of 0.03 mm to 10 mm was formed. The slab was coarsely pulverized by a stamp mill, a jaw crusher or the like according to a usual powder metallurgy method, and then a disc mill, a ball mill, and an attritor were obtained. A method is proposed in which a powder having an average particle size of 3 to 5 μm is finely pulverized by a pulverization method such as a jet mill and then pressed, sintered and aged in a magnetic field to improve performance (JP-A-63-317643). No.).

[0007]

However, the R-F
There is a strong demand for cost reduction of eB-based permanent magnet materials, and it is extremely important to efficiently manufacture high-performance permanent magnets. In addition, it is necessary to improve manufacturing conditions to bring out characteristics close to the limit. Furthermore, miniaturization and weight reduction of today's electric and electronic devices and (BH) max
There is a strong demand for higher functionality of 40 MGOe or more, and it is also required to have excellent squareness of the demagnetization curve, improve corrosion resistance without requiring surface treatment, etc., and further improve the performance of R-Fe-B permanent magnets And cost reduction are required.

In order to increase the residual magnetic flux density (Br) of the R—Fe—BC sintered magnet, 1) it is a ferromagnetic phase and the main phase is R ₂ Fe ₁₄ (B _1-x C _x ). It is required to increase the content of the phase, 2) to increase the density of the sintered body to the theoretical density of the main phase, and 3) to increase the degree of orientation of the main phase crystal grains in the easy axis direction. That is, in order to achieve the above item 1), the composition of the magnet is changed to the above R ₂ Fe ₁₄ (B _1-x C _x )
It is important to make the composition close to the stoichiometric composition.However, if an alloy lump having the above composition is melted and an alloy lump cast in a mold is used as a starting material to prepare an R-Fe-BC sintered magnet, Since α-Fe and R-rich phase crystallized in the alloy lump are locally ubiquitous, there is a problem that pulverization becomes difficult particularly during fine pulverization and a composition deviation occurs.

More specifically, in the case of the conventional ingot crushing method cast in a mold, the above-mentioned α-Fe is present, so that the crushing efficiency at the time of crushing is poor and the particle size distribution of the powder after crushing is broad. Further, since the R-rich phase is locally ubiquitous, the crystal structure of the sintered magnet becomes coarse, and high magnet properties and good squareness of the demagnetization curve cannot be obtained.
Therefore, the alloy block or the coarse powder obtained by pulverizing the alloy is subjected to a solution treatment in order to homogenize and eliminate α-Fe, but this leads not only to an increase in cost but also to coarsening of the main phase crystal grains and segregation of the R-rich phase. Therefore, it is difficult to improve the magnet characteristics of the sintered magnet.

The present invention enables efficient pulverization,
It is excellent in corrosion resistance, expresses a high iHc by making the crystal grains of the magnet finer, and further enhances the degree of orientation of each crystal grain in the direction of easy magnetization, thereby obtaining a high (BH) max value, and the angle of the demagnetization curve. High performance R-Fe- with excellent moldability and corrosion resistance
An object of the present invention is to provide a method for producing a BC permanent magnet material.

[0011]

Means for Solving the Problems The present inventors first use the R-F
Using an e-B-C based alloy as a starting material, the pulverization efficiency is improved, the corrosion resistance is excellent, and the magnetic properties of the sintered magnet, particularly i
As a result of various studies on the magnet composition pulverizing method for the purpose of improving Hc, the structure obtained by the strip casting method was coarsely pulverized into a fine and uniform R-Fe-BC-based alloy, and then to a coarsely pulverized alloy powder. When finely pulverized after adding and blending the lubricant, the fine pulverizing ability is improved about twice as much as before, and after applying a pulsed magnetic field to the fine powder, orienting, shaping and sintering, (BH) ma of the magnetic properties of the magnet
It was found that x and iHc were further improved. Furthermore, as a result of various studies on the alloy composition and the squareness of the demagnetization curve, it was found that the squareness can be significantly improved by optimizing the amounts of B and C.

That is, after an R-Fe-BC-based alloy having a specific composition having a structure in which an R-rich phase of a specific thickness finely separated by strip casting is coarsely pulverized, a lubricant is added to the coarsely pulverized powder. By finely pulverizing, the crystal grains of the main phase constituting the alloy lump can be subdivided, and a powder having a uniform particle size distribution and excellent fluidity can be produced. Preferably H ₂ occlusion decay method as coarse grinding process, when the H ₂ occluded in R-Fe-B-C based alloy having a tissue R-rich phase is separated finely,
It has been found that the alloy can be spontaneously disintegrated by generating a hydride and expanding the volume of the finely dispersed R-rich phase.

In this case, it is particularly important that the R-rich phase is finely dispersed and that the R ₂ Fe ₁₄ (B _1-x C _x ) phase is fine. However, in a method of melting an alloy ingot using an ordinary mold, when the alloy composition approaches the stoichiometric composition of R ₂ Fe ₁₄ (B _{1 -xC x} ), the crystallization of Fe primary crystals occurs. It is unavoidable and causes a great decrease in the fine grinding ability in the next step. Therefore, a means for eliminating α-Fe by applying a heat treatment for the purpose of homogenizing the alloy ingot is taken.
Since this leads to an increase in cost, coarsening of the main phase crystal grains and segregation of the R-rich phase progress, it is difficult to improve the magnetic properties of the sintered magnet.

Further, since it is also an essential condition for achieving high Br that the direction of the easy axis of magnetization of the main phase crystal grains is uniform, that is, the orientation degree is increased, the permanent magnet material manufactured by the powder metallurgy method is used. , For example, hard ferrite magnets,
For the Sm-Co magnet and the R-Fe-B magnet, a method of pressing the powder in a magnetic field is employed. However, considering a coil and a power source of a magnetic field source arranged in a normal press device (a hydraulic press or a mechanical press) for generating a magnetic field for the purpose of increasing the orientation degree, a magnetic field of at most 10 kOe to 20 kOe is considered. However, in order to generate a higher magnetic field, it is necessary to increase the number of turns of the coil, and it is necessary to increase the size of the apparatus to require a high power supply.

The present inventors have analyzed the relationship between the magnetic field strength at the time of pressing and Br of the sintered body. The higher the magnetic field strength, the higher Br can be achieved, and a strong magnetic field is instantaneously generated. It has been found that Br can be further increased by using a pulse magnetic field capable of performing the above.

[0016] Further, as a result of studying the improvement of the filling property into the mold and the improvement of the orientation for the purpose of improving the performance of the magnet, it was obtained from a strip cast slab which had been subjected to H ₂ occlusion and de-H ₂ treatment. After adding a solid lubricant or a liquid lubricant to the coarsely pulverized powder, the mixture is pulverized by jet milling in an inert gas stream and finely pulverized to an average particle diameter of 1 to 5 μm, thereby filling the mold. It was found that a fine powder having excellent magnetic properties and magnetic orientation could be obtained. Furthermore, when this fine powder was used for instantaneous orientation with a pulsed magnetic field, it was possible to further increase the Br. High performance R-Fe with excellent corrosion resistance, magnetic properties and squareness of demagnetization curve by forming in a magnetic field by forming by a hydraulic press or by combining a pulse magnetic field and a static magnetic field by an electromagnet And finding that it is possible to obtain a B-C-based permanent magnet material, and have completed the present invention.

That is, the present invention relates to a method for producing R (where R is at least one kind of rare earth element containing Y) of 12 at% to 18 at%, and B + C =
6 to 10 at% (B: 2 to 6 at%, C: 4 to 8 at%), balance Fe (but Fe
Can be replaced by one or two of Co and Ni) and an alloy melt consisting of unavoidable impurities, by a strip casting method , for example, a thin plate having a thickness of 0.03 mm to 10 mm and an R-rich phase of 10 μm. After casting into a slab having a finely separated structure below, the slab was obtained by coarse pulverization , for example, an average particle size of 10 to
Liquid lubricant or solid lubricant 0.02
5.0 wt% added mixed and pulverized, resulting, for example, a fine powder having an average particle size of 1~10μm into the mold, for example the packing density
Filled into 1.4~3.5g / cm ^3, after momentarily oriented over or a pulse magnetic field of 10 kOe, molding, sintering, corrosion resistance and magnetic properties, characterized in that the aging treatment, especially demagnetization curve This is a method for producing an R-Fe-BC permanent magnet material having excellent squareness.

Further, the present invention is characterized in that, in the construction of the method for producing an R-Fe-BC-based permanent magnet material having excellent corrosion resistance, the coarsely pulverized powder is obtained by an H ₂ occlusion collapse method. Wherein at least one kind of fatty acid ester dissolved in a solvent is used in a liquid lubricant, and zinc stearate, copper stearate, aluminum stearate, and ethylene vinylamide are used as solid lubricants. Characterized in that one type is used, the applied pulse magnetic field is characterized by applying the magnetic field direction in the same direction, the applied pulse magnetic field is characterized by repeatedly inverting the magnetic field direction and applied, Each manufacturing method is also proposed.

With respect to the magnetic properties of the R-Fe-BC permanent magnet according to the present invention, required magnetic properties can be obtained by appropriately selecting the composition, manufacturing conditions, and the like. Details will be described below. The slab of the magnetic material having a structure in which the R-rich phase of the specific composition is finely separated according to the present invention is produced by a single-roll method or a strip-rolling method using a twin-roll method from a molten alloy having the specific composition. The obtained slab is a thin plate material having a thickness of 0.03 mm to 10 mm, and depending on the desired slab thickness, a single roll method or a twin roll method is used properly. When the plate thickness is small, it is preferable to adopt the single roll method.

The reason for limiting the thickness of the slab to 0.03 mm to 10 mm is that if it is less than 0.03 mm, the quenching effect becomes large, the crystal grain size becomes smaller than 3 μm, and it becomes easy to oxidize when powdered. In addition, if it exceeds 10 mm, the cooling rate becomes slow, α-Fe is easily crystallized, and the crystal grain size becomes large.
The uneven distribution of the Nd-rich phase also occurs, which is not preferable because the magnetic properties, particularly the coercive force and the squareness of the demagnetization curve are reduced.

The cross-sectional structure of the R-Fe-BC-based alloy having a specific composition obtained by the strip casting method of the present invention is such that the main phase R ₂ Fe ₁₄ (B _1-x C _x ) crystal is used as a conventional mold. Compared to the ingot obtained by casting, it is finer than about 1/10 or less.
μm to 50 μm, the major axis direction is 5 μm to 200 μm, and the R-rich phase is finely dispersed so as to surround the main phase crystal grains. The size is 20 μm or less.

By finely separating the R-rich phase to 10 μm or less, the volume expansion when the R-rich phase generates a hydride during the H ₂ occlusion treatment is uniformly generated and finely divided. Thus, the crystal grains of the main phase are subdivided to obtain a fine powder having a uniform particle size distribution. The slab remains H
_{Although 2} occlusion treatment may be performed, it is preferable that the metal film is broken to a required size, the metal surface is exposed, and H ₂ occlusion treatment is performed.

For the H ₂ occlusion treatment, for example, a slab having a thickness of 0.03 mm to 10 mm, which has been fractured to a predetermined size, is inserted into a raw material case, and the raw material case is placed in a container that can be sealed by closing a lid. Then, the inside of the container is sufficiently evacuated, and then H ₂ gas at a pressure of 200 Torr to 50 kg / cm ² is supplied to occlude H ₂ in the slab. This H
₂ occlusion reaction, since an exothermic reaction, on the outer periphery of the container to cool the pipe for supplying the cooling water while preventing the Atsushi Nobori of circumferentially to the container, for a predetermined time supply of H ₂ gas at a predetermined pressure As a result, H ₂ gas is absorbed and the slab spontaneously disintegrates and becomes powder. Further, after the powdered alloy is cooled, it is subjected to H ₂ gas removal in a vacuum. Since the alloy powder in the above treatment has fine cracks in the grains, it is finely pulverized in a short time by a ball mill, a jet mill or the like, and an alloy powder having a required particle size of 1 μm to 10 μm can be obtained.

In the present invention, the inside of the processing container may be replaced with an inert gas in advance, and then the inert gas may be replaced with H ₂ gas. Further, breaking the size of the slab, smaller, can reduce pressure of H ₂ pulverization, also H ₂ gas pressure, slab was broken even under a reduced pressure, but is pulverized by H ₂ absorption, the pressure The higher the pressure, the easier it is to pulverize. However, since it is less than 200Torr powdering becomes poor, although preferred in view of powdering by H ₂ absorption exceeds 50 kg / cm ^2, not desirable from the safety of the device and work, H ₂ gas pressure 200Torr~ 50kg / c
and m ^2. From mass production, 2 kg / cm ^{2 to} 10 kg /
cm ² is preferred. In the present invention, the processing time of powdering by occlusion of H ₂ varies depending on the size of the closed container, the size of broken fragments, and the H ₂ gas pressure, but it is necessary to be 5 minutes or more.

After cooling the alloy powder powdered by the H ₂ occlusion, it is subjected to a primary de-H ₂ gas treatment in a vacuum. Further, the powdered alloy is heated to 100 ° C. in a vacuum or argon gas.
When heated to 750 ° C. and subjected to a secondary de-H ₂ gas treatment for 0.5 hours or more, oxidation of the powder or press-molded body due to long-term storage can be prevented, and deterioration of the magnetic properties of the obtained permanent magnet can be prevented. . The dehydrogenation treatment according to the present invention, in which the dehydrogenation treatment is carried out at a temperature of 100 ° C. or higher, has an excellent dehydrogenation effect. The dehydrogenation treatment may be performed in a medium or an argon gas atmosphere.

[0026] That is, after H ₂ absorption and disintegration reaction vessel for H ₂ occlusion reaction described above, performs the dehydrogenation process subsequently resulting collapse powder is heated to above 100 ° C. in an atmosphere of the same container be able to. Alternatively, after the dehydrogenation treatment in a vacuum, the dehydrogenation treatment of the present invention may be carried out by taking out from the processing vessel and pulverizing the disintegrated powder, and then heating it to 100 ° C. or more again in the processing vessel.

The heating temperature in the above dehydrogenation treatment is 1
If the temperature is lower than 00 ° C., it takes a long time to remove H ₂ remaining in the disintegrated alloy powder, and it is not mass-produced. Further, at a temperature exceeding 750 ° C., a liquid phase appears and the powder solidifies, so that fine pulverization becomes difficult or the formability at the time of pressing is deteriorated. Absent.
Further, in consideration of the sinterability of the sintered magnet, a preferable dehydrogenation treatment temperature is 200 ° C to 600 ° C. Further, the processing time varies depending on the processing amount, but it requires at least 0.5 hour.

The feature of the present invention is that a liquid lubricant or a solid lubricant is added to a coarsely pulverized powder having an average particle diameter of 10 μm to 500 μm obtained by the H ₂ occlusion disintegration method in an amount of 0.02 μm or less.
After the addition and mixing of 5 wt%, the powder is pulverized by a jet mill, particularly in an inert gas stream, to obtain a fine powder having an average particle diameter of 1 to 10 μm. As the liquid lubricant in the present invention, a saturated or unsaturated fatty acid ester and a boric acid ester as an acidic salt can be used, and are dispersed in a petroleum solvent or an alcohol solvent. The amount of the fatty acid ester in the liquid oil lubricant is preferably 5 wt% to 50 wt%.

The saturated fatty acid ester is an ester represented by the general formula RCOOR'R = C _n H _{2n + 2} (alkane), and the unsaturated fatty acid ester is a general formula Indicated by

The solid lubricant is at least one of zinc stearate, copper stearate, aluminum stearate, ethylene vinylamide and the like. If the average particle size of the solid lubricant is less than 1 μm, it is industrially produced. When the average particle size is more than 50 μm, it is difficult to mix uniformly with the coarsely ground powder.
~ 50 μm is preferred.

In the present invention, if the amount of the liquid lubricant or the solid lubricant is less than 0.02% by weight, uniform coating of the powder particles is not sufficient, and improvement in mold filling and crystal orientation is recognized. If the content exceeds 5% by weight, the non-volatile residue in the lubricant will remain in the sintered body, causing a decrease in sintering density and deterioration of magnetic properties. The amount is from 0.02 wt% to 5 wt%.

In the present invention, the reason why the average particle size of the coarsely pulverized powder is limited is that if the average particle size is less than 10 μm, it is difficult to handle the raw material powder safely in the atmosphere, and the magnetic characteristics deteriorate due to oxidation of the raw material powder. In addition, if it exceeds 500 μm, it becomes difficult to supply the raw material powder to the jet mill pulverizer, and the pulverization efficiency is remarkably reduced. Therefore, the average particle size of the coarsely pulverized powder is 10 μm to
It is 500 μm.

Next, an inert gas (for example, N
_2. Finely pulverize with a jet mill using Ar). Of course, a ball mill using an organic solvent (for example, benzene or toluene) or an attritor pulverization can be used.

When the average particle size of the finely pulverized powder according to the present invention is less than 1 μm, the powder becomes extremely active, and there is a risk of ignition in a process such as press molding, which deteriorates magnetic properties. If the average particle size exceeds 1, the crystal grains of the permanent magnet obtained by sintering become large, the magnetization reversal easily occurs, and the coercive force is lowered, which is not preferable. Therefore, the average particle size is 1 μm to 10 μm. Preferred average particle size is from 2.5 μm to 4 μm.

The following method is proposed for molding using a pulse magnetic field. The pulverized powder is filled in a mold in an inert gas atmosphere. The mold may be made of a nonmagnetic metal, oxide, ceramics, or the like, or may be an organic compound such as plastic or rubber. The packing density of the powder is
Bulk density of the powder at rest (filling density 1.4 g / cm
³ ) From the bulk density after tapping (packing density 3.5 g /
cm ³ ) is preferred. Therefore, the packing density is 1.4 ~
Limited to 3.5 g / cm ³ .

A pulse magnetic field is applied to the finely pulverized powder filled in the mold by an air-core coil and a capacitor power supply to orient the powder. In the orientation, a pulse magnetic field is applied while compressing using upper and lower punches. carry out. The greater the intensity of the pulse magnetic field, the better, and a minimum of 10 kOe or more is required. The preferred pulse magnetic field strength is 20 kOe
６０60 kOe. In order to continuously perform orientation and pressing by a pulsed magnetic field, a coil for generating a pulsed magnetic field is embedded in the die, oriented using the pulsed magnetic field, and then formed by a normal pressing method in a magnetic field. Is possible.

The pulse magnetic field can be applied only once or repeatedly. In the case of repeatedly applying the magnetic field, only the required direction of the magnetic field is applied.In addition, the orientation can be further improved by alternately inverting the direction of the magnetic field, and the application can be further improved. The magnetic field strength can be applied by gradually decreasing the strength, and when the magnetic field direction is alternately applied, the strength can be gradually reduced, so that the molded body can be apparently denitrified and handled. Has the advantage of being easier. The time of the pulse magnetic field is 1 μsec to 1
0 sec is preferable, and further 5 μsec to 100 ms
ec is preferable, and the number of times of application of the pulse magnetic field is 1 to 10 times,
Further, it is preferably 1 to 5 times.

When applying a magnetic field, it is necessary to appropriately select the application method, the number of times of application, the pulse magnetic field intensity, and the application time in consideration of the desired degree of improvement of the orientation. For example, in the manufacturing method according to the present invention, when the pulse magnetic field to be applied is one time, the maximum energy product (B
H) High-performance RF having a max value of 40 MGOe or more
It is possible to obtain an e-B-C-based permanent magnet material, wherein the characteristic value is equal to or more than 44 MGOe when the magnetic field strength is gradually reversed, and the characteristic value is 44 MGOe or more. Is a high performance R showing a value of 42 MGOe or more.
-It is possible to obtain a Fe-BC-based permanent magnet material.

It is most preferable to form the powder after orientation by compression molding using a cold isostatic press. In this case, it is necessary to appropriately select the hardness and thickness of the plastic mold. It is also possible to manufacture large-sized magnet materials including shaped products. Hydrostatic pressing conditions were as follows:
A pressure of 0 ton / cm ^{2 to} 3.0 ton / cm ² is preferable, and the hardness of the mold is preferably Hs = 20 to 80.
The magnetic field strength of the static magnetic field in that case is preferably 5 to 20 kOe. In addition, the hydrostatic pressing can be performed in a static magnetic field.For example, in orientation, after repeatedly applying the same magnetic field strength while inverting and applying, the powder after orientation is subjected to a hydrostatic pressing in a static magnetic field. , The characteristic value is 46 MGOe
It is possible to obtain a high-performance R-Fe-BC-based permanent magnet material having the above values.

In the present invention, any known powder metallurgical means can be employed for the conditions and methods such as molding, sintering, and heat treatment. An example of preferable conditions is shown below. Before sintering, a general method of heating in a vacuum or a temperature rise of 100 to 200 ° C./hour in a stream of hydrogen and a temperature of 300 to 600 ° C.
It is preferable to carry out the binder removal treatment by a method of maintaining the temperature at about 1 to 2 hours. By performing the debindering treatment, carbon in the binder is decarburized, leading to an improvement in magnetic properties. Note that, since the alloy powder containing the R element easily absorbs hydrogen, it is preferable to perform a dehydrogenation treatment step after the debinding treatment in a stream of hydrogen. In the dehydrogenation treatment, the occluded hydrogen is almost completely removed by raising the temperature at a rate of 50 to 200 ° C./hour in vacuum and maintaining the temperature at 500 to 900 ° C. for about 1 to 2 hours. You.

After the dehydrogenation treatment, it is preferable to carry out sintering by heating and heating continuously, and the heating rate after exceeding 500 ° C. may be arbitrarily selected.
A known temperature-raising method used for sintering, such as 300 ° C./hour, can be employed. The sintering of the molded article after the orientation and the heat treatment conditions after the sintering are appropriately selected according to the selected alloy composition.
Sintering step of holding at 00 to 1180 ° C. for 1 to 6 hours, 45
An aging treatment step of holding at 0 to 950 ° C. for 1 to 8 hours is preferred.

Hereinafter, R-Fe-B according to the present invention will be described.
The reason for limiting the composition of the cast slab for a C-based permanent magnet alloy will be described.
The rare earth element R contained in the cast piece for a permanent magnet alloy of the present invention is a rare earth element containing yttrium (Y) and including light rare earths and heavy rare earths. Usually, one kind of R is sufficient, but in practice, a mixture of two or more kinds (Misshu Metal, Didim, etc.) can be used for reasons such as convenience in obtaining, and Sm, Y, La, Ce, Gd, etc. It can be used as a mixture with other R, especially Nd, Pr and the like. Note that R may not be a pure rare earth element, and may contain impurities that are unavoidable in production within the industrially available range.

R is an essential element of the alloy slab for producing the R-Fe-BC permanent magnet. If it is less than 12 atomic%, high magnetic properties, especially high coercive force cannot be obtained, and 18 atomic% If it exceeds, the residual magnetic flux density (Br) decreases, and a permanent magnet having excellent characteristics cannot be obtained. Therefore, R is 12 atomic% to 1
The range is 8 atomic%. Preferably, R is 13 at% to 1
7 at%.

B and C are essential elements of the alloy slab for producing the R-Fe-BC permanent magnet. If B + C is less than 6 atomic%, a high coercive force (iHc) cannot be obtained, and If it exceeds atomic%, the residual magnetic flux density (Br) decreases,
An excellent permanent magnet cannot be obtained, and when B is less than 2 at%, the residual magnetic flux density decreases and the squareness of the demagnetization curve deteriorates. When B exceeds 6 at%, the corrosion resistance decreases, which is not preferable. When C is less than 4 at%, the corrosion resistance is lowered, which is not preferable.
The amount of -C increases, the residual magnetic flux density Br decreases, and the squareness of the demagnetization curve deteriorates. Therefore, B + C is 6 atomic% to 10 atomic% (however, B 2 to 6a
t%, C4 to 8 at%). Preferred B + C
Ranges from 6 to 8 at%.

Fe is an essential element of alloy slabs for producing R—Fe—BC permanent magnets. If it is less than 72 at%, the residual magnetic flux density (Br) decreases. Since a high coercive force cannot be obtained, the content of Fe is 72 atomic%
Limited to 2 atomic%. The reason why part of Fe is replaced with one or two of Co and Ni is that the effect of improving the temperature characteristics of the permanent magnet and the effect of further improving the corrosion resistance can be obtained. If one or two kinds exceed 50% of Fe, a high coercive force cannot be obtained, and an excellent permanent magnet cannot be obtained. Therefore, one or two of Co and Ni
Species substitution is limited to 50% of Fe.

In order to obtain an excellent permanent magnet having high residual magnetic flux density, high coercive force, excellent squareness of demagnetization curve, and high corrosion resistance in the magnet alloy slab of the present invention, R13 atomic% or more is required. 17 atomic%, B + C = 6-8a
t% (B2 to 4 at%, C4 to 6 at%), Fe7
5 atomic% to 81 atomic% is preferable. Further, the magnet alloy slab according to the present invention can tolerate the presence of unavoidable impurities in industrial production, in addition to C, R, B, and Fe. S of not more than 0.5 atomic%;
By replacing at least one of Cu of 5 atomic% or less with a total amount of 4.0 atomic% or less, it is possible to improve the productivity of the magnet alloy and reduce the cost.

Further, in the R-Fe-BC alloy containing R, B, C, Fe, 9.5 atomic% or less of Al,
7. Ti at most 4.5 atomic%, V at most 9.5 atomic%,
5 atomic% or less of Cr, 8.0 atomic% or less of Mn, 5 atomic% or less of Bi, 12.5 atomic% or less of Nb, 10.5 atomic% or less of Ta, 9.5 atomic% or less of Mo, 9.5 atomic% or less of W, 2.5 atomic% or less of Sb, 7 atomic% or less of Ge, 7 at% or less of Ga, 3.5 atomic% or less of Sn,
By adding at least one of Zr of 5.5 atomic% or less and Hf of 5.5 atomic% or less, a high coercive force of the permanent magnet alloy becomes possible. RB-Fe of the present invention
In the -C permanent magnet, it is essential that the main phase of the crystal phase is tetragonal. Particularly, in order to obtain a fine and uniform alloy powder and to produce a sintered permanent magnet having excellent magnetic properties. It is effective.

[0048]

According to the present invention, after the R-Fe-BC-based alloy having a specific composition of a specific plate thickness subjected to strip casting is roughly pulverized, a specific lubricant is added to the obtained coarsely pulverized powder.
By jet mill pulverization, it becomes possible to subdivide the crystal grains of the main phase constituting the alloy lump, and it is possible to produce a powder having a uniform particle size distribution. If a lubricant is added to the dispersed and R ₂ Fe ₁₄ (B _1-x C _x ) phase-refined alloy powder, and then finely pulverized after compounding, the fine pulverization ability is about twice as high as the conventional one. The manufacturing efficiency is greatly improved, and after the fine powder is instantaneously oriented in a mold using a pulsed magnetic field, pressing and sintering improve mold filling properties and crystal orientation, thereby improving corrosion resistance. In addition, an R-Fe-BC-based permanent magnet having excellent magnetic properties and squareness of the demagnetization curve can be obtained.

[0049]

【Example】

Example 1 An alloy melt having the composition shown in Table 1 obtained by melting in a high-frequency melting furnace was applied to a sheet thickness of about 0.3 using a twin-roll strip caster equipped with two 200 mm-diameter copper rolls.
mm thin plate-shaped slab was obtained. The crystal grain size in the slab is 0.5 μm to 15 μm in the short axis direction and 5 μm in the long axis direction.
m to 80 μm, and the R-rich phase exists finely separated by about 3 μm so as to surround the main phase. The slab is 5
After fracturing to 0 mm square or less, 1000 g of the fragment is housed in a sealed container capable of sucking and discharging, and N ₂ gas is introduced into the container for 3 g.
After flowing for 0 minutes and replacing with air, 3 kg
/ Cm ² of H ₂ gas was supplied for 2 hours to cause the slab to spontaneously disintegrate by H ₂ occlusion, and then subjected to H ₂ removal in a vacuum.
It was cooled to room temperature and further coarsely pulverized to 100 mesh.

Next, 800
g as a liquid lubricant fatty acid ester (active ingredient 50%
After adding 1 wt% of cyclohexane (50%), the mixture was pulverized by a jet mill to obtain an alloy powder having an average particle size of 3.5 μm.
The obtained powder is filled into a urethane rubber mold (inner diameter φ25 × height 20 mm) having a hardness Hs = 40 so as to have a packing density of 3.3 g / cm ³ , and then a pulse magnetic field strength of 40 kO.
e, after once applying and aligning for 8/100 seconds,
The oriented sample was cold isostatically pressed at a press pressure of 1.2 ton / cm ² to obtain a molded body. The molded body taken out of the mold was sintered at 1040 ° C. for 3 hours under the conditions, and subjected to an aging treatment at 900 ° C. for 1 hour to obtain a permanent magnet. Table 2 shows the magnetic properties and corrosion resistance of the obtained permanent magnet.

Example 2 When a fine alloy powder having an average particle size of 3.5 μm obtained under the same composition and under the same conditions as in Example 1 was used to produce a permanent magnet under the same conditions as in Example 1, a pulse magnetic field of 20 kOe was applied. ~ 80k
When Oe is variously changed, the maximum energy product value (BH) max (MGOe) of the obtained permanent magnet is examined, and the relationship with the pulse magnetic field intensity is shown by a broken line in FIG.

Example 3 A strip cast slab having the same composition as in Example 1 was subjected to an H ₂ occlusion treatment under the same conditions as in Example 1 and the collapsible alloy powder obtained was heated and held at 500 ° C. in vacuum for 5 hours. After removing H ₂ , 0.1 wt% of zinc stearate was added as a solid lubricant to 20 μm coarsely pulverized powder.
/ Cm ² Ar gas of a jet mill, and a pulse magnetic field of about 40 kOe was applied once, as in Example 1, 8/10
After applying by applying for 0 second and performing orientation, and then performing cold isostatic pressing, sintering and aging treatment were performed to obtain a permanent magnet. Table 2 shows the magnetic properties and corrosion resistance of the obtained permanent magnet.

Comparative Example 1 An alloy melt having the same composition as in Example 1 was sized 30 mm × 100.
The ingot obtained by casting in a mold of
After breaking to less than an mm square, the fragment was subjected to H ₂ occlusion treatment and de-H ₂ treatment under the same conditions as in Example 1, and then finely divided under the same conditions as in Example 1 without adding a lubricant. Pulverization, pressing in a magnetic field, sintering, and aging treatment were performed to obtain a permanent magnet.
The crystal grain size of the ingot is 30μm in the short axis direction and 300μ in the long axis direction.
m, and the R-rich phase was locally scattered with a size of about 60 μm. Table 2 shows the obtained magnetic characteristics and corrosion resistance results. FIG. 1 shows the particle size distribution of the obtained finely pulverized powder.

Comparative Example 2 An ingot having the same composition as in Comparative Example 1 was fractured to 50 mm or less, and subjected to a solution treatment at 900 ° C. for 10 hours in an inert gas atmosphere. of H ₂ performs storage processing and heat removal H ₂ treatment, after milling the same conditions as in example 1 without the addition of lubricant, the magnetic field during pressing, sintering,
An aging treatment was performed to obtain a permanent magnet. Table 2 shows the obtained magnetic characteristics and corrosion resistance results. FIG. 1 shows the particle size distribution of the obtained finely pulverized powder.

[0055] Comparative Example 3 Comparative Example 1 and an ingot of the same composition to break less than 50mm, after the solution heat treatment of 900 ° C. × 10 hours in an inert gas atmosphere, H ₂ in Example 3 under the same conditions and storage de-H ₂ treatment,
The same lubricant as in Example 1 was added to the coarsely pulverized powder of 20 μm, and finely pulverized by a jet mill to obtain an alloy powder having an average particle size of 3.5 μm.
After applying for 8/100 seconds each time, after orientation, compression molding, sintering and aging treatment were performed to obtain a permanent magnet. Table 2 shows the obtained magnetic characteristics and corrosion resistance results.

Comparative Example 4 Composition: 12.3Nd-2.0Dy-12Co-1.0B
Except for -6.4C-66.3Fe, the same conditions as in Example 1,
A permanent magnet was obtained by the method. Table 2 shows the obtained magnetic properties and corrosion resistance results.

[0057]

[Table 1]

[0058]

[Table 2]

Example 4 In Example 1, a pulse magnetic field of about 40 kOe was applied once.
A permanent magnet was manufactured under exactly the same conditions except that the orientation was performed by applying the voltage four times in 8/100 seconds. Table 3 shows the results of the magnetic characteristics obtained by applying the voltage four times. FIG. 3 shows the relationship between the obtained maximum energy product value (BH) max (MGOe) of the permanent magnet and the number of times of the pulse magnetic field, the first time, the second time, the third time, and the fourth time.

Example 5 In Example 1, a pulse magnetic field of about 40 kOe was applied once.
Permanent magnets were manufactured under exactly the same conditions except that the direction of the magnetic field was alternately inverted and applied four times in 8/100 seconds for orientation. Table 3 shows the results of the obtained magnetic properties obtained by applying four times. FIG. 3 shows the relationship between the obtained maximum energy product value (BH) max (MGOe) of the permanent magnet and the number of times of the pulse magnetic field, the first time, the second time, the third time, and the fourth time. Furthermore, when manufacturing a permanent magnet under the same conditions, the number of pulse magnetic fields is set to 4 and the pulse magnetic field is set to 20 kOe to 80 kOe.
When various values of e were changed, the maximum energy product value (BH) max (MGOe) of the obtained permanent magnet was examined, and the relationship with the pulse magnetic field intensity is shown by a solid line in FIG.

Example 6 In Example 5, the raw material powder was filled into a rubber mold, and the direction of the pulse magnetic field was alternately reversed four times to apply the material powder and oriented. Then, the magnetic field of about 12 kOe was applied by a hydrostatic press. Permanent magnets were manufactured under exactly the same conditions except that cold isostatic pressing was performed at a pressure of 2.5 T / cm ^{2 in} the medium. Table 3 shows the results of the obtained magnetic properties.

Comparative Example 5 In Example 4, 9 parts were added to the finely pulverized powder obtained by the jet mill pulverization.
Compression molding was performed under the same conditions except that a pulse magnetic field of the same direction of kOe was applied once and applied four times in 10/100 seconds, and then sintering and aging were performed to obtain a permanent magnet. Table 2 shows the results of the obtained magnetic properties.

[0063]

[Table 3]

[0064]

The manufacturing method according to the present invention is obtained by forming a molten R-Fe-BC-based alloy having a specific composition into a slab having a specific plate thickness by strip casting, and coarsely pulverizing the slab. By adding and blending a specific lubricant to the alloy powder obtained and pulverizing it with a jet mill, it becomes possible to subdivide the crystal grains of the main phase constituting the alloy lump, and as shown in the Examples, A powder with a uniform distribution
The R-rich phase and the R ₂ Fe ₁₄ B phase are also refined at the time of pulverization, and when magnetized by hydrostatic pressing using one direction or a reversing pulse magnetic field, the orientation is improved. R-Fe-B- with improved and excellent corrosion resistance, extremely high magnetic properties and excellent squareness of demagnetization curve
A C-based permanent magnet is obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing a particle size distribution of finely pulverized powder in an example.

FIG. 2 is a graph showing a relationship between a pulse magnetic field intensity and a maximum energy product value.

FIG. 3 is a graph showing a relationship between the number of times of a pulse magnetic field and a maximum energy product value.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI H01F 1/08 H01F 1/04 H (56) References JP-A-6-290919 (JP, A) JP-A-7-122412 ( JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 41/02 B22F 9/04 C22C 33/02 C22C 38/00 H01F 1/053 H01F 1/08

Claims (7)

(57) [Claims] 1. R (where R is at least one of rare earth elements including Y) 12 at% to 18 at%, B + C
= 6 to 10 at% (B: 2 to 6 at%, C: 4 to 8
at%), the balance Fe (1 part of Fe is Co, 1 part of Ni)
The alloy melt, which can be replaced by one or two types) and unavoidable impurities, is strip- thickened by strip casting.
0.03mm-10mm thin plate, R rich phase is 10μ
m or less, and then a liquid lubricant or a solid lubricant is added to the coarsely pulverized powder obtained by coarsely pulverizing the slab and mixed with 0.02 to 5.0% by weight. And finely pulverized, and the obtained fine powder is filled in a mold, and 10 kOe
After orientation by applying the above pulse magnetic field, molding, sintering,
R-F with excellent corrosion resistance characterized by aging treatment
A method for producing an e-B-C permanent magnet material. 2. The R-Fe-B-C having excellent corrosion resistance according to claim 1, wherein the coarsely pulverized powder is obtained by an H ₂ occlusion disintegration method.
Method for producing permanent magnet materials. 3. The coarsely pulverized powder has an average particle size of 10 to 500 μm.
The R-Fe-B having excellent corrosion resistance according to claim 1,
-A method for producing a C-based permanent magnet material. 4. The method of claim 1, wherein the liquid lubricant has at least one fatty acid ester dissolved therein. 5. The corrosion-resistant R-Fe- according to claim 1, wherein the solid lubricant comprises at least one of zinc stearate, copper stearate, aluminum stearate, and ethylene vinylamide. A method for producing a BC permanent magnet material. 6. The R-Fe-B having excellent corrosion resistance according to claim 1, wherein the applied pulse magnetic field has the same magnetic field direction.
-A method for producing a C-based permanent magnet material. 7. The method for producing an R-Fe-BC-based permanent magnet material having excellent corrosion resistance according to claim 1, wherein the applied pulse magnetic field is applied by reversing the direction of the magnetic field repeatedly.