JPS62222019A - Production of permanent magnet material - Google Patents

Abstract

PURPOSE:To stably produce a permanent magnet material having superior magnet characteristics with improved pressing power by compacting pulverized power consisting of rare earth elements, B and Fe in a magnetic field, crushing the formed green compact into granules, screening the granules, further crushing the screened granules into powder in an AC magnetic field in a hermetically sealed vessel, compacting the powder in a magnetic field and sintering it. CONSTITUTION:Pulverized powder consisting essentially of, by atom, 10-30% R (one or more among Nd, Pr, Dy, Ho and Tb and one or more among La, Ce, Sm, Gd, Er, Eu, Tm, Yb, Lu and Y), 2-38% B and 65-80% Fe is compacted in a magnetic field to orient the grains in a specified direction. The formed green compact is crushed into granules and the granules are screened. The screened granules of 0.1-3mm diameter are put in a hermetically sealed vessel and crushed into powder in an AC magnetic field. The powder is compacted to the required shape and size under orientation in a magnetic field and the formed green compact is sintered. By this method, a permanent magnet material having uniform magnet characterisitcs can be produced in a high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application The present invention relates to a method for producing Fil-B-R permanent magnet materials, and in particular, to a method for producing a Fil-B-R permanent magnet material, in particular a method for producing a raw material powder into a powder with excellent powder properties such as fluidity and Wl transportability. , mold this.

F is sintered and has excellent magnetic properties with no variation.
a. The present invention relates to a manufacturing method for stably obtaining a BR-based permanent magnet material.

BACKGROUND ART Currently, there is a demand for permanent magnet materials that have high magnetic properties and are inexpensive, and there is a strong need for permanent magnet materials that are rich in resources and have compositional elements that can be stably supplied in the future. First, I would like to propose a Fe-BR-based permanent magnet (R is at least one rare earth element including Y) as a new high-performance permanent magnet that does not contain expensive materials.
No. 46008, JP-A-59-64733@, JP-A-59
-89401, JP-A-59-132104). This permanent magnet uses resource-rich light rare earths such as ceramics and circles as R, and is an excellent permanent magnet that has e as its main component and exhibits an extremely high energy product of 20 MGOs or more.

The above novel Fe-B-R system, FeCoB
Rare earth metals as starting materials for producing R-based permanent magnet materials are generally produced by a Ca reduction method or an electrolytic method, for example, by the following steps.

■ As starting materials, rare earth metals, electrolytic iron, ferroboron alloys, or electrolytic 6 are melted at high frequency and cast into ingots.

(2) The ingot is coarsely pulverized using a stamp mill, and then wet pulverized using a ball mill to obtain a fine raw material powder of 1.5 Atm to 10 Atm.

■Mold with orientation in a magnetic field.

■After sintering in vacuum, let it cool.

■Aging treatment in an Ar atmosphere.

Or, ■ At least one of rare earth oxides, at least one of iron powder, pure boron powder, ferroboron powder, and boron oxide, or a mixed powder containing an alloy powder or mixed oxide of the above constituent elements to the required composition. , Gold JlCa and CaCl
2 are mixed and subjected to reductive diffusion in an inert gas atmosphere, and the resulting reaction product is made into a slurry and treated with water.

■The above-mentioned processed material is processed by a ball mill from 0.511m to 5A.
Make a fine powder of Im and make 1 powder.

■Mold with orientation in a magnetic field.

■After sintering in vacuum, let it cool.

■Aging treatment in an Ar atmosphere.

As mentioned above, both the ingot crushed raw material 11 powder and the Ca-reduced raw material powder are fine powders with a particle size of several ρ, so during the orientation molding during magnetization in the above step (2), the raw material into the molding die space is Powder feeding properties are poor, press efficiency is reduced, and due to low fluidity, variations in mold set per press unit are likely to occur, resulting in dimensional variations in the sintered body and problems such as cracks and cracks. In addition, powder conveyance is poor, and it is difficult to automate powder feeding, which frequently poses problems that impede improvements in press productivity and labor saving.

Therefore, in order to solve this problem, the applicant first
Pulverized fine powder is pressurized in an IA magnetic field, the pressurized body is crushed and sized to the required powder particle size, the sized powder is formed into the required shape and size in the magnetic field, and then sintered and aged using a permanent magnet. A manufacturing method was proposed (Japanese Patent Application No. 60-19050).

The raw material powder obtained by the above manufacturing method has excellent powder properties, improves powder feeding into the die space during pressing, and has a great effect on improving press efficiency. Since the powder is crushed and sized to a specific particle size, there is a problem in that the magnetic properties of the resulting permanent magnet tend to vary due to disordered orientation of the raw material powder.

Purpose of the Invention The present invention eliminates the reduction in press efficiency and product quality based on the powder characteristics of raw powder in the production of permanent magnet materials proposed by the applicant whose main components are rare earth elements, boron, and iron. The object of the present invention is to provide a manufacturing method that can stably obtain a FeBR-based permanent magnet material that has excellent magnetic characteristics without any variation.

Structure and Effects of the Invention The inventors investigated various methods of obtaining a permanent magnet material having stable magnetic properties as well as powder characteristics such as fluidity and transportability of the raw material powder, and found that the above-mentioned ingot crushing method or Ca reduction method was used. The finely pulverized powder obtained by this method is pressurized in a specific magnetic field, and this pressed compact is crushed and sized to a specific particle size range to form raw powder, which is then placed in a sealed container such as a die. The crushed powder is then crushed in an alternating magnetic field, formed in a magnetic field, sintered, and magnetized using the conventional process described above, resulting in properties equivalent to or better than permanent magnet materials obtained through the conventional process. A permanent magnet material having a 100% dimensional stability can be stably obtained, and the crushed raw material powder has excellent powder properties, which improves press efficiency, reduces magnetic property and shape dimensional variations during manufacturing, and improves product quality. It was found that this method has a great effect on improving yield.

That is, this invention provides R (R is ceramic, at least one of Pr, h, Ho, Tb, or furthermore, La, Co, Sm,
Gd, Er, EIJ, Tl1l.

consisting of at least one of Yb, Lu, and Y)1
A crushed fine powder whose main components are 0 at% to 30 at%, B2 at% to 28 at%, and Fe65 at% to 80 at% is pressurized in a magnetic field, and the pressurized body has a powder particle size of 0.1. This is a method for producing a magnetic material in which the sized powder is crushed and sized to ~3 mm, placed in a sealed container such as a die, and crushed in an alternating current magnetic field.

The permanent magnet material obtained by the above manufacturing method according to the present invention has an average crystal grain size of 1 to 80. The main phase is a compound with a tetragonal crystal structure in the range of gm, and the volume ratio is 1%.
It is characterized by containing ~50% of a non-magnetic phase (excluding the oxide phase), and mainly uses light rare earths, which are rich in resources, mainly M or rough circles, as R, Fe, B, R, By using Fs-B-R as a main component, it is possible to obtain an Fs-BR permanent magnet material having an extremely high energy product of 20 MGOa or more, a high residual magnetic flux density, and a high coercive force at a low cost.

Preferred Embodiment of the Invention In the manufacturing method according to the present invention, first, a rare earth metal, electrolytic iron, ferroboron alloy, or further electrolysis is melted by high frequency as a starting material to cast an ingot, and this ingot is coarsely pulverized by a stamp mill. Thereafter, the mixture is wet-milled using a ball mill to obtain a finely ground powder.

Alternatively, a mixed powder containing at least one of rare earth oxides, at least one of iron powder, pure boron powder, ferroboron powder, and boron oxide, or an alloy powder or mixed oxide of the above-mentioned constituent elements in the required composition, Metal Ca and C
The reaction product obtained by mixing aCN2 and performing reductive diffusion in an inert gas atmosphere is made into a slurry, treated with water, and the treated product is ball milled to obtain finely pulverized powder.

Using the above finely pulverized powder as a raw material, in order to align the crystal grains in the granulated powder in a specific direction, press pressures of o, st, g to 3. Ot, J, for example, pressurized with a pair of rolls or molded using a normal press device in a magnetic field, and the molded body is crushed and sized using a crusher to form a powder. Particle size from 0.1mm to 3mm
Align within the range.

Thereafter, the sized powder is placed in a sealed container such as a die, and the sized powder is crushed in an alternating current magnetic field of 10,000 a to 100,000 e.

The obtained crushed powder is molded into a desired shape and one dimension through the powder metallurgy manufacturing process described above, for example, by orientation in a magnetic field.
After sintering in a vacuum, the material is left to cool, and then subjected to an aging treatment in an Ar atmosphere to obtain a permanent magnet material.

In this invention, if the magnetic field under pressure in the magnetic field before crushing and grading is less than 8 kOa, the orientation of the powder will be insufficient and the magnetic properties will deteriorate, which is undesirable.
If it exceeds koa, it is not preferable because it causes the problem of increased manufacturing equipment cost.

In addition, if the pressing pressure is less than 0.5t4, it is not possible to obtain a sized powder with sufficient strength, and it is not possible to improve the powder properties, which is undesirable. This is undesirable because the punch wears out excessively, making continuous work difficult.

In this invention, if the particle size of the crushed sized powder is less than 0.1 mm, it is not preferable because there is a problem of decreased fluidity.
If it exceeds 3 mm, it is not preferable because it will cause variations in the weight per press unit during powder feeding in presses for small items, and the particle size of the sized powder should be 0.1 mm to 3.0 mm, preferably 0.3 mm to 0.3 mm. The particle size is 8 mm.

The above-mentioned crushing of the sized powder, which is a feature of this invention, involves the sized powder stored in a sealed container such as a die, moving and rotating against each other in an alternating magnetic field, causing repeated friction and collision. This allows the particles to be crushed without disturbing their orientation.

If the alternating current magnetic field during crushing is less than 10,000 a, it will take a long time to crush to the required particle size, which is undesirable.
If it exceeds 00,000 s, the magnetic field generator will become large and the equipment will require a lot of cost.
The range of s is preferable, and the crushing time is desirably 1 minute or less.

Further, in this invention, the 1 s field condition when forming the crushed raw material powder into the required shape and 2 dimensions in a magnetic field is 7 koa.
~20 koa is preferable, and the press conditions are 9.5t6
~8t4 is preferred.

In addition, the temperature conditions for sintering are 900'C to 1200°C.
is preferable, and more preferably from 1000°C to 1100°C
'C, the time is preferably 30 minutes to 8 hours. 900'
If it is less than Q, sufficient strength as a sintered magnet cannot be obtained,
If the temperature exceeds 1200'C, the sintered body will be deformed, the orientation will be destroyed, the magnetic flux density will decrease, the squareness will decrease, and the crystal grains will become coarser, which will reduce the coercive force, which is not preferable. .

In addition, in this invention, in order to improve the residual magnetic flux density, coercive force, and squareness of the demagnetization curve of the magnet material, 350
It is preferable to carry out an aging treatment at a temperature of 0.degree. C. to a sintering temperature. If the aging temperature is less than 350° C., there is no effect because the diffusion rate decreases, and if it exceeds the sintering temperature, resintering occurs and oversintering occurs.

In general, the aging treatment temperature is preferably in the range of 450°C to 800°C, and the aging treatment time is preferably 5 minutes to 40 hours. If the aging treatment is carried out for less than 5 minutes, the effect of the aging treatment will be small, and the magnetic properties of the obtained magnet material will vary greatly, and if it exceeds 40 hours, it will take too long for industrial use to be practical. The aging treatment time is 3 from the viewpoint of preferable development of magnetic properties and practical aspects.
Preferably 0 minutes to 8 hours. Moreover, multi-stage aging treatment of two or more stages can also be used for the aging treatment.

Also, instead of multi-stage aging treatment, 400℃~1000'C
0.2°C/min to 20'C/min by air cooling or water cooling from the aging treatment temperature to room temperature.
A permanent magnet material having magnetic properties equivalent to those obtained by the above-mentioned aging treatment can also be obtained by a method of cooling at a cooling rate of .

Reason for limiting the ingredients of the raw material powder for permanent magnet material 1 The rare earth element R used in the powder of permanent magnet material 1 of this invention accounts for 10 to 24 atomic percent of the composition,
, Ho, and at least one of Tb, or roughly,
La, Ce, Sm, Cd, Er, Eu, T
m.

Yb, 10. Those containing at least one type of Y are preferred.

Also, usually one type of R (preferably Nd or Pr).

Dv, Ho, Tb, etc.) may suffice, but in practice, a mixture of two or more types (Mitsuhmetal, didymium, etc.) may be used for reasons such as convenience of availability.

In addition, 5TIII L! in R that constitutes the main phase! It is preferable to have as little C as possible; for example, Sm is at most 1 atomic %, more preferably at most 0.5 atomic %.

In addition, in order to improve the temperature characteristics, as an R mixed system, m
, Pr, or N in an amount of 0.005 atom % to 5 atom %, preferably 0.2 atom % to 3 atom %.

A combination of Ho, Tb, etc. is desirable.

Furthermore, from the viewpoint of characteristics, cost, and resources, R:
It is preferable that Ceramic and Pr account for 50% or more of the total R, preferably 80% or more.

Note that this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within an industrially available range.

R is in the new raw material powder for the above-mentioned permanent magnet material,
Rarely for essential elements, in less than 10 atomic %, the crystal structure is α
- Since a cubic crystal structure with the same structure as iron is precipitated, high magnetic properties, especially high coercive force, cannot be obtained, and if it exceeds 30%,
The R-rich nonmagnetic phase increases, and the residual magnetic flux density (Sr)
decreases, making it impossible to obtain a permanent magnet with excellent characteristics. Therefore, the rare earth element is in the range of 10 atomic % to 30 atomic %.

B is an essential element that is present in the raw material powder for permanent magnet materials according to the present invention, and when it is less than 2 atomic %, the rhombohedral MA
structure becomes one phase, high coercive force (iHC) cannot be obtained, and 2
When it exceeds 8 at%, B-rich nonmagnetic phase increases,
Since the residual magnetic flux density (Sr) decreases, an excellent permanent magnet cannot be obtained. Therefore, B is 2 atom% to 28 atom%
The range shall be .

Fe is an essential element in the above-mentioned new permanent magnet material, 1'+l raw material powder, and if it is less than 65 at%, the residual magnetic flux density (Br) will decrease, and if it exceeds 80 at%, it will have a high coercive force. 1q, Fe is contained in an amount of 65 to 80 atom %.

In addition, replacing a portion of Fe in the raw powder for permanent magnet material 1 according to the present invention can improve the temperature characteristics without impairing the magnetic properties of the resulting magnet. If the amount of 6-substitution exceeds 20% of Fa, the magnetic properties will deteriorate, which is not preferable. When the atomic ratio of Sn is 5% to 15% for the total concavity of Fe and Co, (Br) increases compared to the case where it is not substituted, which is preferable for obtaining a high magnetic flux density.

Further, the permanent magnet material according to the present invention includes R, B.

In addition to F8, the presence of unavoidable impurities in industrial production can be tolerated, but a portion of B is C12 of up to 4.0 atom %, P of up to 0 atom %, S of up to 0 atom %, S, 2. 0 atomic%
Improving the manufacturability of permanent magnets by replacing at least one of the following Cu in a total amount of 2.0 atomic % or less,
It is possible to lower the price.

Furthermore, at least one of the following additional elements is RB −
It can be added to the Fe-based permanent magnet material 1 because it is effective in improving the coercive force and squareness of the demagnetization curve, improving manufacturability, and reducing cost.

A1 of 5.0 atom% or less; 1115 of 3.0 atom% or less
．． 5 at% or less V, 4.5 at% or less cr, 5.0
Nn below 5.0 atomic %, Bi below 9,0 atomic %, Nb below 7.0 atomic %, to, below 5.2 atomic %, to below 5.0 atomic % buttocks.

1.0 at% or less sb, 3.5 at% or less Ge, 1
．． S content of 5 atomic% or less, Zr, B of 3.3 atomic% or less,
Ni of O atomic % or less, 5i11.1 of 5.0 atomic % or less
Addition of at least one of Zn of atomic% or less and Hf of 3.3 atomic% or less.However, if 2 or more types 8 are present, the maximum content is the atom of the element having the maximum value among the added elements. % or less, it becomes possible to increase the coercive force of the permanent magnet. Note that the upper limit of the additive base was determined to be a range that satisfies this condition, since (Br) is required to be at least 9 kG or more in order to make the (Btl) max of the magnet material 1 208 GOe or more.

It is essential that the main phase of the crystalline phase is a tetragonal one in order to produce a sintered permanent magnet having superior magnetic properties than a fine and uniform alloy powder.

In addition, the permanent magnet material 1 of the present invention can be press-molded in an ia lift field to obtain a magnetically anisotropic magnet, and can be press-molded in a non-magnetic field to obtain a magnetically isotropic magnet. be able to.

The permanent magnet material according to the present invention has a coercive force i IIc≧1
koa, residual magnetic flux density Br > 4 kG, and the maximum energy product (Btl) max is 208 GOa or more, and in a preferred composition range, the maximum value is 258 GOa.
Reach more than a.

In addition, in the case where the main component of R in the raw material powder for permanent magnet materials of this invention is light rare earth metals mainly composed of ceramic and yen, R12 at % to 15 at % and B6 at %
When the composition range is ~9 at%, F878 at% ~ 80 at%, (8 old ma reach.

Examples Example 1 Electrolytic iron with a purity of 99.9%, ferroboron alloy, ceramics with a purity of 99.7% or more, and N are used as starting materials, and these are mixed and high-frequency melted, and then placed in a water-cooled copper mold. Casting was performed to obtain an ingot having a composition of 14.5Nd 7B 0.5Dy78Fe.

Thereafter, this ingot was coarsely ground using a stamp mill, and then finely ground using a ball mill to obtain an average particle size of '3.0u.
A fine powder of m was obtained.

This fine powder was oriented in a magnetic field of 10 koa using a magnetic field press machine, and then pressure-molded at a pressure of 1.5 t, J.
A molded body with dimensions of 00 mm x 60 mm x 50 mm was made.

The obtained pressurized body was sized to a powder particle size of 0.4 mm using a sieving machine.
It was crushed and sized to a size of ~0.6 mm.

The above sized powder is 15n+mX 20mmX 20mm
After charging the powder into a die of the same size, the inner space of the die was sealed with upper and lower punches, and an alternating current magnetic field of 40,000 e was applied for 5 seconds to crush the sized powder.

This crushed powder was charged into the same mold, oriented in a magnetic field of 12 koa, and molded with a pressure of 2 tJ in a direction parallel to the magnetic field to form a molded body with dimensions of 15 mm x 20 mm x 12 m 1 T1.

The obtained molded body was sintered at 1080°C for 1.5 hours in an Ar atmosphere, and then sintered at 80°C in an Ar atmosphere.
Two-stage aging treatment was performed at 0°C for 1 hour and at 630'C for 1.5 hours.

The magnetic properties of the obtained permanent magnet material were measured, and the results are shown in Table 1 along with the press efficiency.

In addition, in the comparative example shown in Table 1, the powder obtained by sizing the above-mentioned in-place hot melt to a specific particle size was used as the raw material powder, which was put into a die as it was, compacted in a magnetic field, and subjected to aging treatment after sintering. The other manufacturing conditions were the same as in the examples of the present invention.

Table 1

Claims (1)

[Claims] R (R is at least one of Nd, Pr, Dy, Ho, and Tb, or furthermore, La, Ce, Sm, Cd, Er
, Eu, Tm, Yb, Lu, Y) 10 atomic % to 30 atomic %, B2 atomic % to 28 atomic %, and Fe65 atomic % to 80 atomic %. is pressurized in a magnetic field, the pressurized body is crushed and sized to a powder particle size of 0.1 to 3 mm, the sized powder is placed in a sealed container, and the crushed powder is crushed in an alternating magnetic field. A method for producing a permanent magnet material, which comprises forming powder into a required shape and size in a magnetic field, and then sintering it to obtain a permanent magnet.