JPS6119701A - Preparation of sintered magnet material - Google Patents

Abstract

PURPOSE:To obtain a sintered magnet material improved in moldability and having high magnetic characteristics, by adding a specified moldability modifier to a powdery alloy having a specific composition consisting of a rare earth element, B and Fe, and molding the resulting alloy composition before sintering the same under a specific condition removing said modifier. CONSTITUTION:At least one moldability modifier selected from polyoxyethylene alkyl ether, polyoxyethylene fatty acid monoester and polyoxyethylene alkylarly ether is added to and mixed with a powdery alloy (an average particle size of about 1-10mum) based on 10-30atom% of a rare earth element including Y, 2-28atom% of B and 65-82atom% of Fe in an amount of 0.5pts.wt. or less per 100pts.wt. of the powdery alloy. The resulting mixture is molded and sintered at 100-350 deg.C under vacuum of 20-1X10<-4>Torr to remove the moldability modifier.

Description

[Detailed Description of the Invention] Field of Application This invention relates to a method for producing a sintered magnet material whose main components are R (where R is at least one rare earth element including Y), B, and Fe. In particular, the present invention relates to a method for producing a REIFe-based sintered magnet material that improves the moldability of raw material alloy powder and provides high magnetic properties.

BACKGROUND ART Permanent magnetic materials are one of the extremely important electrical and electronic materials used in a wide range of fields, from various household appliances to peripheral terminal equipment for large computers. In recent years, with the demand for smaller size and higher efficiency of electrical and electronic equipment, permanent magnet materials are required to have increasingly higher performance.

Therefore, the applicant first proposed 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 Sm. No. 57-145072). Furthermore, F
In order to improve the temperature characteristics of a permanent magnet made of an e-B-R system magnetically anisotropic sintered body, by replacing a part of Fe with ω, the Curie point of the resulting alloy is raised by one point, and the temperature characteristics are improved. Fe-C with improved

-El-R A permanent magnet made of an optically anisotropic sintered body was proposed (Japanese Patent Application No. 166663/1983).

The above novel Fe-El-R system, Fe-Co-El-R
The rare earth metal that is the starting material for manufacturing permanent magnets (R is at least one rare earth element including Y) is generally a metal lump produced by a Ca reduction method or an electrolytic method, and this rare earth metal lump For example, by the following steps,
The novel permanent magnet described above is manufactured.

■ As a starting material, electrolytic iron with a purity of 99.9%, 819
．． A ferroboron alloy containing 4% and the remainder is Fe and impurities such as #, SL, C, pure [99.7% or more rare earth metal, or further electrolysis with a purity of 99.9%] is melted by high frequency, and then Cast in a water-cooled copper mold, ■ Coarsely pulverize to 35 mesh through using a stamp mill, and then wet-pulverize, for example, 300 g of coarsely pulverized powder for 6 hours using a ball mill to form a fine powder of 3 to 10 ρ. ■ Magnetic field (10 KOe) ) Facing the inner door, mold (pressure at 1.5t4). (1) Sintering at 1000°C to 1200°C for 1 hour. After sintering in Ar, allow to cool.

■ Aging treatment, 500°C to 1000°C, in Ar.

As mentioned above, 1q of this alloy powder for permanent magnets is obtained by mechanically coarsely and finely pulverizing an ingot of the desired composition.
If the powder is left as it is, the moldability is very poor, and due to friction with the die wall surface etc. during molding, scratches, peeling, etc. are likely to occur on the die surface and the surface of the molded product, which has a big impact on quality and product yield. It was a problem.

To improve moldability, binders and lubricants such as paraffin wax, stearic acid, bisamide, or zinc stearate have conventionally been added.

However, paraffin wax has a small effect on improving moldability, and when used in large quantities, it inhibits the magnetic field orientation of the alloy powder, making it difficult to become anisotropic.Also, in the subsequent sintering process, carbon is added to the sintered body. In the case of stearic acid, there is a problem of reducing the strength of the compact, and in the case of bisamide and zinc stearate, it is difficult to uniformly disperse them in the alloy powder. There was a problem in that the alloy powder itself was not completely prevented from sticking to the friction surface such as the die surface, resulting in scratches on the compact and the die surface.

In order to improve the formability of alloy powder for permanent magnets, the inventor
We investigated a moldability improver that has excellent dispersibility and excellent lubricity to greatly reduce the friction between the die surface and the molded object, has a high moldability improvement effect, and does not cause deterioration of the magnetic properties of the magnet. As a result, by mixing the moldability improver described below and then molding, the moldability of the alloy powder is significantly improved and high molded body strength is obtained, and furthermore, the continuous moldability of thin-walled molded bodies is greatly improved. We found that it was improved.

However, if the molded body is sintered with the formability improver still present in the molded body, the sintering reaction will be inhibited and it will be difficult to obtain a complete sintered body, and the sintering reaction will progress. Even if this is done, it is known that the decomposed carbon of the improver remains in the sintered body, degrading the magnetic properties of the sintered body.

For this reason, for example, Japanese Patent Application Laid-Open No. 110602/1983 has proposed a method for removing organic binders from sintered magnet alloys. The moldability was not improved, and since the processing temperature in vacuum was high, the alloy powder of the present invention had the problem that a large amount of carbon remained in the sintered body, degrading the magnetic properties.

Purpose of the Invention The present invention improves the formability of the R-13-Fe based magnet alloy powder, removes the formability improver that does not inhibit the magnetic properties during the production of the magnet alloy, and improves the formability during sintering. The object of the present invention is to provide a method for manufacturing a sintered magnet in which residual carbon does not cause deterioration of the magnetic properties of the sintered body.

Structure and Effects of the Invention This invention was developed as a result of various studies on moldability improvers used in molding alloy powder for permanent magnets containing R, B, and Fe as main components. It has been found that at least one selected from ethylene monofatty acid ester and polyoxyethylene alkyl allyl ether is optimal, and it has excellent dispersibility in alloy powder and has excellent lubricity even when added in small amounts. This has the advantage that the friction between the die surface and the compact is greatly reduced, the moldability is highly improved, and the magnetic properties of the sintered magnet are not deteriorated.

Furthermore, by blending at least one of solid paraffin and camphor with excellent bonding properties into the above-mentioned moldability improver, the friction area with the die can be increased, and the friction area can be increased and It has been found that the continuous moldability of a thin-walled molded body that is thin in a direction perpendicular to the friction surface is significantly improved.

That is, the solid paraffin and/or camphor are uniformly dispersed within the alloy powder due to the large dispersion properties of the moldability improver, and the synergistic effect of the bonding properties and the lubrication properties of the improver produces a large frictional force. It exhibits excellent preventive power and durability against the occurrence of scratches caused by.

As a result of studying a method for removing the above-mentioned moldability improver having such excellent moldability, it was found that by removing the moldability improver at 100°C to 350°C under a vacuum of 20 Torr to 1X10-4 Torr. It was discovered that the amount of residual carbon in the sintered body has no effect on the magnetic properties of the sintered body.

However, in this invention, R10 atomic% to 30 atomic% (however, R is at least one kind of rare earth elements including Y), B 2 atomic% to 28 atomic%
At %, e 65 at % to 82 at %, to the alloy powder whose main component is polyoxyethylene alkyl ether, poly';Av-
At least one moldability improver selected from silyl-ethylene monofatty acid ester and polyoxyethylene alkyl allyl ether is added in an amount of 0.3 parts by weight or less per 100 parts by weight of the above alloy powder, or further, At least one type of moldability improver among solid paraffin and camphor is added to the above alloy powder - 100%
Add 2.5 parts by weight or less to parts by weight, mix, mold, and mold under a vacuum of 20 Torr to 1xlO-4 Torr.
This method of producing a sintered magnet material is characterized in that the moldability improver is removed and then sintered at a temperature of 00°C to 350°C.

The alloy powder of the present invention is chemically active, and is contaminated with the moldability improver or its decomposition products, especially at high temperatures, resulting in poor sintering of the molded body and impairing the magnetic properties of the sintered body. It is necessary to remove the moldability improver and prevent contamination as much as possible, but if the removal temperature exceeds 350°C, the moldability improver will decompose rapidly and the alloy powder will become more active, resulting in severe contamination. Furthermore, if the temperature is below 100°C, it will take a long time to remove the moldability improver and a high degree of vacuum will be required.
Because of this disadvantage, the removal treatment temperature is set at 100°C to 350°C. □If the degree of vacuum is less than 2 (llorr) to 760 T'orr, the moldability improver and its decomposition products will take a long time in the atmosphere, and the residue in the atmosphere will not be able to rise for sintering. The high temperature during the thermal process contaminates the alloy powder, which is a serious problem especially when processing a large number of molded bodies.

In addition, the degree of vacuum is higher than 1X10-4 Torr.
In vacuum, the alloy powder becomes active even at low temperatures,
Since the magnetic properties of the sintered body are deteriorated by reacting with the formability improver or its decomposition products, a degree of vacuum not exceeding 1 x 10-' TOrr is required.

In this invention, the degree of vacuum and temperature of the above-mentioned removal processing conditions can be carried out under constant conditions or by changing stepwise or continuously, and during the removal processing, the vacuum However, by controlling the treatment temperature, the amount of transpiration can be adjusted.

In addition, the removal processing time needs to be selected appropriately depending on the size of the molded body, the processing amount, etc., and can also be determined depending on the degree of vacuum arrival, and the preferable processing time is 2 hours to 10 hours.
It's time.

Reason for limitation of moldability improver In this invention, polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl nial, polyoxyethylene higher alcohol ether, or a mixture thereof, and a long chain alkyl is preferred.

In addition, the polyoxyethylene hepta) fatty acid esters include polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol monooleate, or mixtures thereof, and esters of long-chain fatty acids are preferred and are not included during their production. Although a diester such as polyethylene glycol distearate can be used, it is preferable that a monoester is the main component.

Further, the polyoxyethylene alkyl allyl ether is polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, or a mixture thereof, and the alkyl preferably has a long chain.

Two or more of the above polyoxyethylene alkyl ethers, polyoxyethylene monofatty acid esters, and polyoxyethylene alkyl allyl ethers can be used in combination, and in the case of wet mixing with alloy powder, it is possible to , polyoxyethylene alkyl ether, polyoxyethylene monofatty acid ester, and polyoxyethylene alkyl allyl ether preferably have an HLB (hydrophilicity/lipophilicity ratio) of 20 or less.

General commercial products can be used as the solid paraffin, and in order to improve the strength of the molded product, it is preferably wax-like, wax-like, or solid at room temperature. Therefore, it is preferable that the molecular weight is not very large, and it is preferable that the number of carbon atoms is 50 or less. On the other hand, general commercially available camphor can also be used.

In this invention, the amount of the above moldability improver added alone or in combination is determined by the particle size of the raw material alloy powder, the die size,
It may be selected as appropriate depending on the shape and dimensions of the compact, friction area, press conditions, etc. Addition of a small amount has a large effect on improving moldability, and as the amount added increases, moldability improves significantly, but alloy powder 100 If the amount of the above-mentioned modifier added exceeds 0.3 parts by weight and the amount of solid paraffin and/or camphor added exceeds 2.5 parts by weight, the magnetic properties of the permanent magnet will deteriorate. Therefore, the upper limit of the addition amount needs to be 0.3 parts by weight and 2.5 parts by weight, respectively, and the preferable addition amount is 0.01 part by weight to 0.2 part by weight of the moldability improver. solid paraffin and/or camphor in an amount of 0.01 to 2.0 parts by weight.

Also, a moldability improver, solid paraffin and/or.

The mixing ratio of camphor is not particularly limited, but the ratio of the former to the latter is preferably 1/30 to 5/1.

In addition, in this invention, it is preferable to add the organic formability improver to the alloy powder in a wet manner because the alloy powder is reactive and active with oxygen or moisture. is hexane, toluene,
Trichlorethylene.

Inert solvents such as fluorine-based solvents are preferred. The mixing state may be either a dry state or a slurry state, and for example, mixing may be carried out as appropriate during or before or after the wet pulverization process, or during or before or after the drying process.

In the present invention, the alloy powder can be molded in the same manner as a normal powder metallurgy method, and an anisotropic magnet or an isotropic magnet can be obtained depending on whether or not a magnetic field is applied during pressure molding.

Reasons for limiting the composition of the permanent magnet alloy powder In the following, the reasons for limiting the composition of the rare earth/iron/boron based raw material alloy powder for permanent magnets in this invention will be explained.

The rare earth element R contained in the raw material alloy powder for permanent magnets of the present invention is a rare earth element that includes ythrium (Y) and includes light rare earths and heavy rare earths.

As R, a light rare earth element is sufficient, especially Nd.

Pr is preferred. Also, one type of R is usually sufficient, but in practice, a mixture of two or more types (Mitushmetal, Didim, etc.) can be used for reasons such as convenience of availability.
5II1. Y, La, Ce, Gd.

etc. can be used as a mixture with other R1, especially Nd, Pr, etc. 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 (at least one rare earth element including Y) is an essential element as an alloy powder for manufacturing the new above-mentioned permanent magnet, and if it is less than 10 atomic %, high magnetic properties, especially high coercive force, cannot be obtained. First, if it exceeds 30 atomic %, the residual magnetic flux density (Br) 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 as an alloy powder for manufacturing the new above-mentioned permanent magnet, and if it is less than 2 atomic %, it will have a high coercive force (
iHC) cannot be obtained, and if it exceeds 28 atom %, the residual magnetic flux density (Br) decreases, making it impossible to obtain an excellent permanent magnet. Therefore, B is in the range of 2 atomic % to 28 atomic %.

Fe is an essential element as an alloy powder for manufacturing the new above-mentioned permanent magnets, but if it is less than 65 at%, the residual magnetic flux density (Br) decreases, and if it exceeds 82 at%, a high coercive force cannot be obtained. Therefore, Fe is 65 at% to 82 at%
limited to.

In addition, the reason why part of Fe is replaced with CO is that it has the effect of improving the temperature characteristics of the permanent magnet, and CO
If it exceeds 50% of Fe, a high coercive force cannot be obtained and an excellent permanent magnet cannot be obtained.

Therefore, the upper limit of CO is 50%.

In order to produce an excellent permanent magnet having both high residual magnetic flux density and high coercive force in the alloy powder of this invention, R10 to 25 atom%, B4 to 26 atom%, l:e G5 It is preferably from atomic % to 82 atomic %.

Further, the alloy powder according to the present invention is R, B.

In addition to Fe, the presence of unavoidable impurities in industrial production can be tolerated, but a part of B can be added to 4.0 at% or less of 01, 3.5 at% or less of P, and 2.5 at% or less of S13.5.
At least one type of Cu of atomic% or less, total amount 4
．． By substituting at 0 atomic % or less, it is possible to improve the manufacturability and reduce the cost of the magnet alloy.

Furthermore, in the R, B, Fe alloy or the R, B, Fe alloy containing CO, 9.5 atomic % or less of AU, 4.5 atomic % or less of TI, 9
．． 5 atomic% or less ■, 8.5 atomic% or less Or, 8.0
Mn 15 atomic % or less B 111 2.5 atomic % or less (7) Nb 110.5 atomic % or less Ta.

9.5 atomic % or less MO19, 5 atomic % or less W.

Sb of 2.5 atomic % or less, Qe of 7 atomic % or less.

3n of 35 atomic% or less, Zr of 5.5 atomic% or less,
By adding at least one kind of Hf of 5.5 atomic % or less, it is possible to increase the coercive force of the permanent magnet alloy.

It is essential that the main crystal phase be tetragonal in order to obtain a fine and uniform alloy powder. .

The particle size of the alloy fine powder according to the present invention has an average particle size of 107
．． If it exceeds n, excellent magnetic properties, especially high coercive force, cannot be obtained when producing a permanent magnet, and the average particle size is 1.
If it is less than ρ, oxidation will be significant in the permanent magnet manufacturing process, that is, press forming, sintering and 1 aging treatment process, and excellent magnetic properties will not be obtained.
The most desirable is a fine alloy powder.

The magnetically anisotropic permanent magnet alloy obtained using the alloy fine powder for permanent magnets according to the present invention has a coercive force i f-1c≧I
KOe, residual magnetic flux density Br > 4KG, maximum energy product (81-1) max is equal to or higher than hard ferrite, and in the most preferable composition range, (BH)
max≧10MGOe, and the maximum value reaches 25MGOe or more.

Further, when the composition of the alloy fine powder according to the present invention is R10 at% to 30 at%, B2 at% to 28 at%, C45 at% or less, and Fe 65 at% to 82 at%, the obtained magnetic anisotropy The permanent magnet alloy exhibits magnetic properties equivalent to those of the above-mentioned magnet alloy, and the temperature coefficient of residual magnetic flux density is 0.1%.
/℃ or less, and excellent characteristics can be obtained.

In addition, when the main component of R in the alloy powder is 50% or more of the light rare earth metal, R12 atomic % to 20 atomic %, B
The best magnetic properties are exhibited when the content is 4 at% to 24 at%, Fe 65 at% to 82 at%, or further Co is 5 to 45 at%, especially when the light rare earth metal is ceramic. , (BH)max reaches a maximum value of 33 MGOe or more.

Examples] As a starting material, electrolytic iron with a purity of 99.9%, 819.4
% and the remainder is impurities such as Fe and C. A predetermined amount of porcelain with a purity of 99.7% or more is blended and high frequency melted, then cast in a water-cooled copper mold, and heated to 151V &
An ingot having a composition of 18B 77Fe (at%) was obtained.

This ingot was mechanically crushed to a 35-mesh through-hole. Then, it was finely pulverized using a ball mill to obtain an alloy powder with an average particle size of 3.3ρ.

To this alloy powder, as shown in Table 1, moldability improvers are added alone or in combination, each in an amount of 0.05 to 0.2 parts by weight per 100 parts by weight of the alloy powder, dissolved in trichlorotrifluoroethane or The dispersed material was wet mixed and then dried.

Using this dry alloy powder, it was oriented in a magnetic field of 12 KOe, pressure molded at 1.5 t4, and a width of 15 mm x length of 16 mm was formed.
After molding into a molded body of mm x height 10 mm, it was removed under the film treatment conditions of the moldability improver shown in Table 1, except for the comparative example, which was not subjected to the same treatment and was heated at 1100 ° C 11 in Ar gas.
Sintered under the conditions of 600℃ in Ar gas,
A permanent magnet was produced by performing aging treatment for 1 hour.

The magnetic properties and residual C amount of the obtained permanent magnet were measured, and the results are shown in Table 2.

As is clear from Table 2, it is clear that the permanent magnets produced by the method of this invention, which have been subjected to film treatment with a formability improver, have excellent magnetic properties and have a significantly reduced amount of residual C.

The following margins are Table 1 Table 2 Example 2 As a starting material, electrolytic iron with a purity of 99.9%, E119.
A ferroboron alloy containing 4% and the remainder is impurities such as Fe and C, M metal with a purity of 99.7% or more, and electrolysis are mixed in predetermined amounts, high frequency melted, and then cast in a water-cooled copper mold. j 7810Co67Fe (at%)
An ingot with the following composition was obtained.

After coarsely crushing this ingot, it is finely crushed to have an average particle size of 3.0.
A large amount of alloy powder was obtained.

To 100 parts by weight of this alloy powder, 0.1 to 0.50 parts by weight of a combination of two types of organic moldability improvers and solid paraffin or camphor shown in Table 3 are added in advance to 100 parts by weight of trichlorotrifluorochloride. The solution in ethane was added and mixed, after which it was dried.

Using this dry alloy powder, it was oriented in a magnetic field of 12 KOe and pressure-molded at 1.5 tJ to form a shape with a width of 15 mm and a length of 16 mm.
After molding a molded body of mm x height 10 mm, it was treated with a film of a moldability improver shown in Table 3, except for the comparative example, which was treated under the treatment conditions of the present invention, at 1100°C in Ar for 1 hour.
The magnet was sintered under the following conditions and further subjected to aging treatment at 600° C. for 1 hour in At to produce a permanent magnet, and its magnetic properties were measured. The measurement results are shown in Table 4.

As is clear from Table 4, it is clear that the permanent magnet produced by the method of the present invention, which has been subjected to film treatment with a formability improver, has excellent magnetic properties and the amount of residual C is extremely reduced.

Margin below □ ■ Book Departure Akira [゛ old 1 ratio 1 Comparison 1

Claims (1)

[Claims] The main components are R10 at% to 30 at% (wherein R is at least one kind of rare earth elements including Y), B2 at% to 28 at%, Fe65 at% to 82 at%, At least one moldability improver selected from polyoxyethylene alkyl ether, polyoxyethylene monofatty acid ester, and polyoxyethylene alkyl allyl ether is added to the alloy powder 1.
After adding 0.5 parts by weight or less to 00 parts by weight, mixing and molding, under a vacuum of 20 Torr to 1 x 10^-^4 Torr,
A method for producing a sintered magnet material, which comprises sintering after removing the formability improver at 100°C to 350°C. An alloy powder whose main components are R 10 atomic % to 30 atomic % (however, R is at least one kind of rare earth elements including Y), B 2 atomic % to 28 atomic %, Fe 65 atomic % to 82 atomic %, At least one moldability improver selected from polyoxyethylene alkyl ether, polyoxyethylene monofatty acid ester, and polyoxyethylene alkyl allyl ether is added to the alloy powder 1.
0.3 parts by weight or less per 100 parts by weight of the above alloy powder, and at least 2.5 parts by weight or less per 100 parts by weight of the above alloy powder were added and mixed. It is then molded under a vacuum of 20 Torr to 1 x 10^-^4 Torr.
A method for producing a sintered magnet material, which comprises sintering after removing the formability improver at 100°C to 350°C.