JP2571403B2 - Manufacturing method of rare earth magnet material - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing an Fe-BR based rare earth magnet, and relates to a raw material powder obtained by mixing and mixing a required amount of a Ca reduced powder and an ingot pulverized powder. Accordingly, the present invention relates to a method for producing an Fe-BR-based rare earth magnet having uniform, stable and excellent magnet properties.

BACKGROUND ART The applicant has previously proposed an Fe-BR-based (R is at least one of rare earth elements including Y) permanent magnet as a new high-performance permanent magnet that does not contain expensive Sm or Co (Japanese Patent Application Laid-Open (JP-A) No. 2002-110630). Akira
59-46008, JP-A-59-64733, JP-A-59-89401, JP-A-59-132104).

This permanent magnet uses a resource-rich light rare earth element, mainly Nd and Pr, as R and contains 20MGOe
It is an excellent permanent magnet that exhibits an extremely high energy product.

The above-mentioned novel Fe-BR-based and Fe-Co-BR-based permanent magnet materials are usually manufactured by the following steps.

As a starting material, a rare earth metal, electrolytic iron, ferroboron alloy or electrolytic Co is melted by high frequency to produce an ingot.

The ingot is roughly pulverized by the H ₂ occlusion pulverization method, and then wet pulverized by a ball mill to obtain a fine powder raw material powder of 1.4 μm to 5 μm.

Or a mixed powder obtained by mixing at least one of rare earth oxides, at least one of iron powder and pure boron powder, ferroboron powder and boron oxide, or an alloy powder or mixed oxide of the above constituent elements in a required composition. , Metal Ca and CaCl ₂ are mixed, and the reaction product obtained by performing reduction diffusion in an inert gas atmosphere is slurried and treated with water.

b. The treated material is finely pulverized to 0.5 to 5 μm by a ball mill to obtain a raw material powder.

The ingot pulverized powder or Ca reduced powder obtained in the above step or the ab step is molded in a magnetic field orientation.

 After sintering in vacuum, it is allowed to cool.

 Aging treatment in Ar atmosphere.

However, the ingot pulverized powder obtained in the above step has a smaller O ₂ content than the Ca reduced powder obtained in the ab step, but has an effective Nd during sintering.
Since the rich layer is distributed more than the Ca reduced powder, the magnet properties of the sintered magnet obtained from the ingot pulverized powder have a problem that the squareness of the demagnetization curve is inferior to that of the Ca reduced powder.

Further, Ca reduction powder obtained by the ab step, after the reduction, since (after ie reduction CaO) Ca reducing agent water is used in step of removing, compared to ingot ground powder, containing O ₂ Since the amount is large and the content of O ₂ varies greatly, the composition of the obtained sintered magnet body tends to vary,
There is a problem that the magnet characteristics vary.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional method for producing a rare earth magnet using raw material powders, and produces a Fe-BR based rare earth magnet having uniform, stable, and excellent magnet properties. How to aim.

Structure and Effect of the Invention The present invention is based on the results of various studies on the properties and the like of the raw material powder in order to solve the problems of the conventional method of manufacturing a rare earth magnet using the raw material powder. the formulation of ingot powder and Ca reduction powder for a magnet is controlled to a specific amount, to reduce the amount of O ₂ contained in the mixed raw material powder obtained, then press and sintered, variation of the magnet composition It was found that an Fe-BR-based permanent magnet having excellent magnet properties, especially excellent squareness of the demagnetization curve, was obtained.
The present invention has been completed.

That is, the present invention relates to R (R is at least one of Nd, Pr, Dy, Ho, Tb, or at least one of La, Ce, Sm, Gd, Er, Eu, Tm, Yb, Lu, Y) Consists of) 27wt% -37wt%, B0.5wt
% ~5wt%, Fe58wt% ~72.5wt% , O 2 2000ppm~5000pp
40 to 95% of Ca reduced powder containing m as a main component, and R (R is Nd, P
at least one of r, Dy, Ho, and Tb, or L
a, Ce, Sm, Gd, Er, Eu, Tm, Yb, Lu, Y) at least 27 wt% to 37 wt%, B0.5 wt% to 5 wt%
%, Fe58wt% ~72.5wt%, a 5% to 60% ingot ground powder mainly composed of O ₂ 500ppm~2500ppm mixed formulation, R27～37wt
%, B0.5~5wt%, after adjusting the O ₂ content of the mixed raw material powder having a Fe58～72.5Wt% below 3500 ppm, after milling the mixed powder particle size of less than 5μm pressing, sintering, aging A method for producing a rare earth magnet material.

The composition of the rare earth permanent magnet material obtained by the production method of the present invention is such that each of the Ca reduced powder and the ingot crushed powder is the same as the target permanent magnet material composition, and the respective powders have different compositions, for example. Even if the contained rare earth element is different or the content of each composition is different, the quality is stable and if the O ₂ content in the powder is adjusted to 3500 ppm or less, particularly the predetermined target composition after the mixing adjustment, and The effect of improving the magnet characteristics can be obtained.

The permanent magnet material obtained by the production method of the present invention comprises a compound having a tetragonal crystal structure having an average crystal grain size in a range of 1 to 80 μm as a main phase, and a non-magnetic material having a volume ratio of 1% to 50%. Phase (excluding oxide phase), R is mainly composed of Nd or further rare earth, which is rich in resources centered on Pr, and is mainly composed of Fe, B, and R. It has an extremely high energy product of 20 MGOe or more, a high remanence flux density, a high coercive force, and it is possible to inexpensively obtain a Fe-BR-based permanent magnet material having stable quality and excellent squareness of a demagnetization curve. it can.

Preferred Embodiment of the Invention The production method according to the present invention comprises:
A rare earth metal, electrolytic iron, ferroboron alloy or further electrolytic Co is melted by high frequency to produce an ingot, and this ingot is H ₂
Coarsely pulverized by natural collapse by occlusion to obtain an ingot pulverized coarsely pulverized powder having a particle size of 10 to 40 μm.

Alternatively, the Ca-reduced powder in the present invention comprises at least one of rare earth oxides, iron powder, at least one of pure boron powder, ferroboron powder and boron oxide, or an alloy powder or a mixed oxide of the above constituent elements. Metal Ca and CaCl ₂ are mixed with the mixed powder blended in the required composition, and the reaction product obtained by performing reduction diffusion in an inert gas atmosphere is slurried, and further treated with water, 30μ
m is obtained.

The composition of the Ca reduced powder and the ingot pulverized powder of the present invention is as follows: R (R is at least one of Nd, Pr, Dy, Ho, and Tb, or further La, Ce, Sm, Gd, Er, Eu, Tm, Other than Yb, Lu, and Y) 27 wt% to 37 wt%, B0.5 wt% to 5 wt%, Fe58 wt% to 72.5 wt%, Co, Al, Ti, V, Cr , Mu, Si, Nb, Ta,
At least one of Mo, W, Sb, Ge, Sn, Zr, Ni, Si, Zu, and Hf may be contained in a specific amount.

The O ₂ content in the Ca reduced powder, the ingot pulverized powder, and the mixed powder is as follows.

Ca reduction powder is less than 2000ppm is O ₂ content in the powder, it is not necessary to adjust the oxygen content blended ingots pulverized powder, and 2000ppm or higher, exceeds 5000 ppm,
Since a large amount of oxides in the raw material powder causes instability of the magnet properties, even if the oxygen content is adjusted by blending the ingot pulverized powder, the effect is small. Therefore, O _{2 in} Ca reduced powder
The content is preferably in the range of 2000 ppm to 5000 ppm.

Further, to reduce the O ₂ content in the ingot pulverized powder to less than 500 ppm is industrially impossible to produce, and 2500 ppm
If it exceeds, the effect of contributing to the adjustment of the oxygen content of the Ca reduced powder is small, so the O ₂ content in the powder is 500 ppm to 2500 p.
A range of pm is preferred.

O ₂ content in the mixed powder after mixed adjusted two raw material powders above, exceeds 3500 ppm, the more the oxygen content of the sintered magnet body, the effective rare earth content is reduced, the magnet properties Since the deterioration is remarkable and there is no advantage of mixing the Ca reduced powder and the ingot pulverized powder to utilize the characteristics of both, the O ₂ content in the powder is set to 3500 ppm or less.

The Ca reduced powder and the ingot coarsely pulverized powder are mixed, and the oxygen content in the mixed powder is adjusted to 3500 ppm or less to improve the magnet properties of the obtained sintered magnet, and then finely pulverized. Pulverize to 1.5-5 μm.

When the particle size of the mixed powder is less than 1.5 μm, the degree of oxidation of the powder becomes large, and the magnet characteristics are deteriorated, which is not preferable. When the particle size exceeds 5 μm, the crystal size of the permanent magnet obtained after sintering becomes large. This is not preferable because the magnetization reversal occurs easily and the coercive force decreases.

As described above, the obtained fine powder, powder metallurgical manufacturing process, for example, after shaping to the required shape and dimensions in a magnetic field orientation, after sintering in a vacuum, further release in an Ar atmosphere A permanent magnet material is obtained through a step of aging treatment.

Further, in the present invention, the magnetic field conditions for molding the raw material powder into a required shape and dimensions in a magnetic field are 7 kOe to 13 kOe.
e is preferably, pressing ^{conditions, 0.5t / cm 2 ~8t / cm} 2 is preferred.

Further, the temperature condition in sintering is preferably 900 ° C to 1200 ° C, more preferably 1000 ° C to 1100 ° C, and the time is 30 ° C.
Minutes to 8 hours are preferred.

If the sintering temperature is less than 900 ° C, sufficient strength as a sintered magnet body cannot be obtained, and if it exceeds 1200 ° C, the sintered body will be deformed,
It is not preferable because the orientation is lost, the magnetic flux density is reduced, the squareness of the demagnetization curve is reduced in the future, and the crystal grains become coarse and the coercive force is reduced.

Further, in the present invention, the residual magnetic flux density of the magnet material,
350 to improve and improve the coercive force and squareness of the demagnetization curve
It is preferable to perform aging treatment at a temperature from ℃ to sintering temperature. If the aging temperature is lower than 350 ° C, there is no effect because the diffusion rate decreases.
If the temperature exceeds the sintering temperature, resintering occurs and oversintering occurs.

Further, the aging temperature is preferably in the range of 450 ° C. to 800 ° C., and the aging time is preferably 5 minutes to 40 hours.
If it is less than 5 minutes, the aging treatment effect is small, and the magnetic properties of the obtained magnetic material vary greatly. If it exceeds 40 hours, it takes an industrially long time and is not practical.

The aging treatment time is preferably from 30 minutes to 8 hours from the viewpoint of the preferred manifestation of magnetic properties and the practicality. The aging process may be a multi-stage aging process of two or more stages.

Also, instead of the multi-stage aging treatment, a method of cooling from an aging treatment temperature of 400 ° C. to 1000 ° C. to room temperature by a cooling method such as air cooling or water cooling at a cooling rate of 0.2 ° C./min to 20 ° C./min. A permanent magnet material having the same magnetic properties as the aging treatment can be obtained.

Reasons for Limiting Components of Raw Material Powder The rare earth element R used in the raw material powder for a permanent magnet material of the present invention accounts for 27 to 37 wt% of the composition, but Nd, Pr, Dy, H
o, at least one of Tb, or La, Ce, S
Those containing at least one of m, Gd, Er, Eu, Tm, Yb, Lu, and Y are preferable.

Usually, one of R (preferably Nd, Rr, Dy, H
o, Tb, etc.), but in practice, a mixture of two or more (mish metal, dymium, etc.) can be used for reasons such as convenience in obtaining.

Further, it is preferable that Sm and La in R constituting the main phase are as small as possible. For example, Sm is 2 wt% or less, more preferably 0.5 wt% or less.

In order to improve the temperature characteristics, as an R mixed system,
Preference is given to Nd, Pr or a combination of 0.01 wt% to 10 wt%, preferably 0.3 wt% to 7 wt% of Dy, Ho, Tb or the like.

Further, from the viewpoints of characteristics, cost and resources, it is preferable that Nd and Pr occupy 50% or more, more preferably 80% or more of the total R as R.

Note that R may not be a pure rare earth element, and may contain impurities which are unavoidable in production within the industrially available range.

R is an essential element in the new raw material powder for a permanent magnet material, and if less than 27 wt%, the crystal structure is α
-A cubic structure with the same structure as iron precipitates, so high magnetic properties, especially high coercive force, cannot be obtained. If it exceeds 37 wt%, R-rich non-magnetic phase increases and residual magnetic flux density (Br) decreases. As a result, a permanent magnet having excellent characteristics cannot be obtained. Therefore,
The rare earth element is in the range of 27 wt% to 37 wt%.

B is an essential element in the raw material powder for a permanent magnet material according to the present invention, and if it is less than 0.5 wt%, the rhombohedral structure becomes the main phase and a high coercive force (iHc) cannot be obtained, and 0.5 wt%
Exceeding the equation (1), the B-rich nonmagnetic phase increases and the residual magnetic flux density (Br) decreases, so that an excellent permanent magnet cannot be obtained. Therefore, B is in the range of 0.5 wt% to 5 wt%.

Fe is an essential element in the new raw material powder for a permanent magnet material, and when the content is less than 58 wt%, the residual magnetic flux density (B
If r) decreases and exceeds 72.5 wt%, a high coercive force cannot be obtained, so Fe is contained in an amount of 58 wt% to 72.5 wt%.

Further, in the raw material powder for a permanent magnet material according to the present invention, substituting a part of Fe with Co can improve the temperature characteristics without impairing the magnetic characteristics of the obtained magnet.

However, if the Co substitution amount exceeds 20% of Fe, the magnetic properties are adversely deteriorated, which is not preferable. In addition, when the atomic ratio of Co is 5% to 15% in the total amount of Fe and Co, (Br) increases as compared with the case of substitution, which is preferable for obtaining a high magnetic flux density.

The permanent magnet material according to the present invention can tolerate impurities unavoidable in industrial production in addition to R, B, and Fe.

For example, part of B is at least one of C of 0.5 wt% or less, P of 1 wt% or less, S of 1 wt% or less, and Cu of 2 wt% or less.
By replacing the seeds with a total amount of 2 wt% or less, it is possible to improve the productivity of permanent magnets and reduce the cost.

Further, at least one of the following additional elements is Fe-B
-It can be added to the R-based permanent magnet material because it has the effect of improving the coercive force and the squareness of the demagnetization curve or improving the productivity and reducing the price.

2 wt% or less Al, 2 wt% or less Ti, 4.5 wt% or less V, 3.5 wt% or less Cr, 4 wt% or less Mn, 15 wt% or less Bi, 13 wt% or less Nb, 20 wt% or less Ta, 8 wt% or less Mo, 14 wt% or less W, 2 wt% or less Sb, 4 wt% or less Ge, 3 wt% or less Sn, 5 wt% or less Zr, 5.5 wt% or less Ni, 2 wt% or less Si, 1 wt% % Or less of Zn and 9 wt% or less of Hf. However, when two or more are contained, the maximum content is the amount of wt% or less of the additive element having the maximum value. , It is possible to increase the coercive force of the permanent magnet material. Note that the upper limit of the addition amount is that (Br) must be at least 9 kG or more in order to make the (BH) max of the magnet material 20 MGOe or less,
The range was set so as to satisfy the conditions.

It is indispensable that the main phase of the crystal phase be tetragonal in order to produce a sintered permanent magnet having better magnetic properties than a fine and uniform alloy powder.

Above, the reasons for limiting the composition of each of the Ca reduced powder and the ingot pulverized powder have been described, but each powder composition is not necessarily the same as the composition of the intended permanent magnet material obtained by mixing and blending, Each powder may have a different composition, for example, a different rare earth element or a different composition content.

Further, Fe-B- obtained by the production method of the present invention.
The composition range of the R-based permanent magnet material is the same as the range of the powder composition described above, and the reason for the limitation is also the same.

The permanent magnet material according to the present invention has a coercive force iHc ≧ 1 kOe,
Residual magnetic flux density Br> 4kG, the maximum energy product (B
H) max shows 20MGOe or more, and in a preferable composition range,
The maximum reaches more than 25MGOe.

Further, in the case where the main component of R in the raw material powder for a permanent magnet material of the present invention is 50% or more of light rare earth metal mainly composed of Nd and Pr, R27wt% to 34wt%, B0.8wt% to 1.6wt% , Fe
When the main component is 60wt% ~ 72wt%, (BH) max25MGOe
It shows the above excellent magnetic properties, especially when the light rare earth metal is Nd
In the case of, the maximum value reaches 42MGOe or more.

Examples Example 1 As starting materials, electrolytic iron powder having a purity of 99.7%, ferroboron alloy, Nd and Dy metal having a purity of 99.7 were used, and after blending, high frequency melting was performed and cast into a water-cooled mold, and Nd was 27.4 wt%. ,
An ingot having a composition of Dy 3.4 wt%, B 1.1 wt%, Fe 67.8 wt%, and the balance of impurities was obtained.

Thereafter, the ingot was subjected to H ₂ occlusion pulverization to obtain an average particle size of 30 μm.
m were obtained.

In addition, 99.0% pure Nd,
After mixing and mixing metal Ca particles and CaCl2 using Dy oxide, 99.8% electrolytic iron powder and ferroboron alloy powder, the reaction product obtained by performing the reduction diffusion reaction in an inert gas atmosphere is obtained. Slurry and further water washing, Nd27.5wt
%, Dy3.5 wt%, B1.2 wt%, Fe67.5 wt%, and powder having an average particle size of 21 μm having a balance of inevitable impurities.

The oxygen content of these raw material powders was 1100 ppm for the ingot pulverized powder and 4000 ppm for the Ca reduced powder.

These two raw material powders were blended at the blending ratios shown in Table 1 and finely pulverized by an attritor using an organic solvent to obtain fine powders having an average particle size of 2.8 μm.

The obtained mixed raw material fine powder having various mixing ratios was inserted into a mold, oriented in a magnetic field of 15 kOe, and molded at a pressure of ² t / cm ² .

Thereafter, the compact was sintered at 1100 ° C. for 3 hours in an Ar gas atmosphere, further subjected to an aging treatment at 600 ° C. for 2 hours, and then rapidly cooled to produce a permanent magnet according to the present invention.

Further, for comparison, a permanent magnet was produced under the above-mentioned production conditions using the single powder of the Ca reduced powder and the ingot pulverized powder.

Table 1 shows the magnet properties (average values) of the obtained permanent magnets. Table 2 shows the variation range of the magnet characteristics.

Example 2 As starting materials, 99.7% pure electrolytic iron powder, a ferroboron alloy, 99.7% pure Nd and Dy metal were used. After blending these, they were melted by high frequency and cast into a water-cooled mold, and 27.2 wt% Nd,
An ingot having a composition of Dy 2.3 wt%, B 1.1 wt%, Fe 68.8 wt%, and the balance of impurities was obtained.

Thereafter, the ingot was subjected to H ₂ occlusion pulverization to obtain an average particle size of 32 μm.
Was obtained.

Also, 99.0% pure Nd, Dy
After mixing and mixing metal Ca particles and CaCl2 using oxides, 99.8% pure electrolytic iron powder and ferroboron alloy powder, the reaction product obtained by performing the reduction diffusion reaction in an inert gas atmosphere is slurried. Nd27.0wt%
A powder having a composition of Dy 2.5 wt%, B 1.2 wt%, Fe 68.8 wt%, and the balance of inevitable impurities having an average particle size of 17 μm was obtained.

The oxygen content of these raw material powders is 15
The amount of 00 ppm and Ca reduced powder was 4300 ppm.

The obtained two kinds of raw material powders were blended at the blending ratio shown in Table 3, and finely pulverized by an attritor using an organic solvent to obtain a fine powder having an average particle size of 2.6 μm. It was inserted into a mold, oriented in a magnetic field of 15 kOe, and molded at a pressure of ² t / cm ² .

The molded body was sintered at 1100 ° C. for 3 hours in an Ar gas atmosphere, and then subjected to an aging treatment at 500 ° C. to 600 ° C. for 2 hours and rapidly cooled to produce a permanent magnet according to the present invention.

Further, for comparison, a permanent magnet was produced under the above-mentioned production conditions using a single powder of the Ca reduced powder and the ingot pulverized powder, and a powder mixed within a range outside the scope of the present invention.

Table 3 shows the magnet properties (average values) of the obtained permanent magnets. Table 4 shows the variation range of the magnet characteristics.

Claims (1)

(57) [Claims] 1. A Fe—BR system (R is at least one of Nd, Pr, Dy, Ho, and Tb, or La, Ce, Sm, Gd, E
r, Eu, Tm, Yb, Lu, Y) At least 40% by weight to 95% by weight of a Ga reduced powder for a magnet, and 5% by weight to 60% by weight of an ingot pulverized powder for the Fe-BR-based magnet % were mixed formulation, R27~37wt%, B0.5~5wt%, after adjusting the O ₂ content of the mixed raw material powder having a Fe58～72.5Wt% below 3500 ppm, milling, pressing, sintering A method for producing a rare earth magnet material.