WO2012017574A1

WO2012017574A1 - Anisotropic rare earth bonded magnet and production method therefor

Info

Publication number: WO2012017574A1
Application number: PCT/JP2011/001857
Authority: WO
Inventors: 日登志山本
Original assignee: 株式会社Kri
Priority date: 2010-08-04
Filing date: 2011-03-29
Publication date: 2012-02-09
Also published as: JPWO2012017574A1; JP2013145769A

Abstract

Although anisotropic rare earth bonded magnets have superior magnetic properties to isotropic bonded magnets, there are currently issues with temperature properties, corrosion resistance, and magnet costs, and mass production is not widespread. Meanwhile, although methods are available for recycling sintered magnet scrap, such as dissolving and alloying scrap to obtain magnet alloys, and using oxide reduction, separation of SmCo and Nd magnets is unavoidable, and scrap must first be returned to a rare earth oxide state. A low-cost, highly-efficient recycling method has currently not been found. The present invention proposes a novel anisotropic rare earth bonded and a production method therefor that utilize this sintered magnet scrap to produce magnets that are superior to commercially-available isotropic bonded magnets, and that are easy on the environment due to energy saving and resource conservation. Anisotropic rare earth bonded magnets are produced by means of crushing, strain relief annealing heat treatment, kneading, and magnetic field forming.

Description

Anisotropic rare earth bonded magnet and manufacturing method thereof

The present invention relates to an anisotropic rare earth bonded magnet manufactured from a rare earth anisotropic sintered magnet and a manufacturing method thereof.

Rare-earth sintered magnet is energy saving, reduction in size and weight of the equipment, home appliances against the background of the needs of high performance, personal computers, digital cameras, mobile phones, office equipment OA, such as a motor FA equipment, hybrid by CO ₂ warming in recent years With the addition of applications such as automobiles and electric cars, these demands are growing more and more and their consumption is increasing year by year.

Rare earths contained in rare earth sintered magnets are rare in Japan, relying 100% on imports from China, the United States and Australia, more than 95% of which are in China. In recent years, there has been concern about the supply of long-term rare earth (hereinafter referred to as “RE” as appropriate) resources, and the rare earth resource problem is an extremely important issue for maintaining Japan's advanced technology.

As described above, it is predicted that the amount of rare earth sintered magnet scrap to be discarded in the future will increase, and since these rare resources, which are rare resources, are included in considerable quantities, recovery and reuse technologies are required.

Many proposals have been made to obtain a magnet alloy by melting and alloying rare earth magnet scraps again (for example, Patent Document 1). These require not only remelting and alloying in order to produce a magnet product again, but also a magnet process of crushing, molding, sintering, and heat treatment, and the purchase of RE raw materials is more cost-effective. Moreover, the process (patent document 2) which reduces | reduces after separating magnet scraps into each rare earth, the method (patent document 3) which takes a decarbonization process and a Ca reduction | restoration process, decarbonization, a reduction | restoration, and a washing | cleaning process are required (patent document 4) ). In addition, the cost of waste liquid from the factory is high, and there are significant problems in terms of environmental measures. Alternatively, a plating removal method (Patent Document 5) and an adhesive removal (Patent Document 6) which are impurities at the time of recycling these recovery processes are necessary and not yet put into practical use.

JP 2003-113429 A JP2002-60855 JP 2004-91811 A JP 2005-57191 A JP2001-40425 JP2003-176659

As mentioned above, no method has been found to efficiently recycle the rare earth sintered magnet scraps at low cost. The present invention proposes a novel anisotropic rare earth bonded magnet obtained by recycling a rare earth sintered magnet and a method for producing the same.

In view of the above background, it is an object to provide an anisotropic bonded magnet having high magnetic characteristics, temperature characteristics, and corrosion resistance, which is higher than before, by effectively utilizing rare earth sintered magnet scraps.

The present invention aims to provide a high performance anisotropic rare earth bonded magnet, does not use any conventional recycling process of rare earth magnet materials, has no problem of waste liquid treatment such as acid, and separates and refines Sm and Nd. No need for process, no need for peeling of surface treatment film such as Ni plating, no need to remove adhesive, but magnetic properties are inferior to those of commercially available Nd sintered magnets. The present invention provides a novel anisotropic rare earth bonded magnet superior to a bonded magnet and a method for producing the same, and has the following characteristics.

[1] As components other than iron (Fe), at least neodymium (Nd) is 13 to 35 wt%, boron (B) is 0.3 to 1.3 wt%, samarium (Sm) is 0 to 30 wt%, cobalt (Co ) 0-15 wt%, nickel (Ni) 0-5.5 wt%, aluminum (Al) 0-5.5 wt%, and nickel (Ni) and aluminum (Al) combined at 0.3 wt% %, The balance being iron (Fe), the maximum energy product (BH) max is 96 to 270 kJ / m ³ , and the average particle size of the pulverized raw material is 30 to 200 μm (micron) And an anisotropic rare earth bonded magnet characterized in that the main phase forming each particle has a structure with an average crystal grain size of 1 to 15 μm (microns).

[2] A method for producing an anisotropic rare earth bonded magnet using a rare earth anisotropic sintered magnet as a raw material, the step of mechanically grinding the rare earth anisotropic sintered magnet in an inert atmosphere, and the pulverized material From a step of strain relief annealing at a temperature of 400 to 600 ° C. at a temperature of 400 to 600 ° C. in a high vacuum or an inert atmosphere, and a step of kneading the material subjected to the strain relief annealing treatment with a binder to form a magnetic field. A method for producing an anisotropic rare earth bonded magnet, comprising:

[3] The method for producing an anisotropic rare earth bonded magnet according to [2], wherein the rare earth anisotropic sintered magnet is recovered scrap.

[4] The rare earth anisotropic sintered magnet may be neodymium sintered magnet collection waste or a mixture of neodymium sintered magnet collection waste and samarium cobalt sintered magnet collection waste. An anisotropic rare earth bonded magnet manufacturing method.

[5] When the rare earth anisotropic sintered magnet recovery scrap is a mixed scrap, the recovered scrap is sampled in advance and subjected to component analysis of the recovered magnet material before being subjected to the pulverization process, and the composition of neodymium and neodymium and samarium is determined. The manufacturing method of the anisotropic rare earth bond magnet as described in said [3] including the process to confirm.

[6] The method for producing an anisotropic rare earth bonded magnet according to [2], wherein the magnetic field molding includes a compression molding step, and a wet molding method is used in the compression molding step.

[7] The method for producing an anisotropic rare earth bonded magnet according to [6], wherein in the compression molding step, two-stage press molding is performed in which a CIP step is performed after the compression molding.

According to the present invention, an anisotropic rare earth bonded magnet having remarkably excellent magnetic properties can be obtained. Further, one of the greatest characteristics in performance of the anisotropic bonded magnet according to the present invention is heat resistance, specifically, thermal demagnetization characteristics.

In addition, one of the additional features of the anisotropic rare earth bonded magnet of the present invention is high corrosion resistance, and the magnet has long-term stability that can be applied to long-term use. is there.

Furthermore, according to the manufacturing method of the present invention, it is not necessary to re-dissolve and alloy rare earth magnet scraps, which is one of the conventionally proposed methods for recycling rare earth sintered magnets, to regenerate rare earth sintered magnets. Can be used.

In addition, according to the present invention, an anisotropic rare earth bonded magnet can be manufactured without removing the adhesive adhering to the magnet and before the surface treatment peeling removal such as Ni plating, Al plating or epoxy resin. It can be simplified.

Furthermore, in the present invention, even if the waste magnet of the rare earth sintered magnet contains an SmCo magnet, the separation step at the time of RE purification of SmCo and Nd magnet waste, which has been inevitable in the past, is completely unnecessary. Conventionally, the purpose is to use the recovered scrap for sintered magnet applications, but the present invention is applied to a bonded magnet. There is no high-temperature processing step in the process of manufacturing the bonded magnet of the present invention, and individual bonding magnet powders show independent magnetic characteristics, so that arbitrary mixing is possible.

That is, the feature of the present invention is that there is no problem of separation and recovery of the above-mentioned SmCo magnet and Nd magnet, there is no need to peel and remove the magnet surface treatment film, which is inevitable in the current magnet recycling process, With almost no removal and reusable magnet material composition, there is no limit to the amount of recovered materials such as Ni, AI, Cr as surface treatment materials and O and C as impurity elements. It is possible to recover.

In addition, regarding the molding process of this magnet, the advantage of being able to provide bonded magnet powder with excellent corrosion resistance reliability due to extremely few surface cracks and breakage that occur during molding is the reason that this material is made from a microcrystalline sintered material Enclose with.

A further feature of the present invention is that it is characterized by using an anisotropic rare earth sintered magnet raw material as a raw material, and thus has a much higher coercive force and higher heat resistance than conventional anisotropic rare earth bonded magnets. (That is, a normalized squareness ratio p value (p = Hk / HcJ) defined as described later) is obtained.

The anisotropic rare earth bonded magnet according to the present invention is an anisotropic rare earth bonded magnet manufactured from a rare earth anisotropic sintered magnet. As the rare earth anisotropic sintered magnet as a raw material, an anisotropic rare earth sintered magnet recovered from the city can be used. There are also isotropic Nd bond magnets and isotropic full dense (dense) Nd magnets in the city's collected scrap, and there is an idea to collect and reuse these collected scraps. It is preferable to use a rare earth anisotropic sintered magnet. In other words, anisotropic rare earth sintered magnets are very long processes of alloy melting, grinding, magnetic field molding, sintering, heat treatment, processing, and surface treatment, that is, even “waste” is “recovered waste with very high added value”. This is because it is not desirable to reduce the reuse and energy reuse efficiency by mixing other magnets. The present invention is a high-value-added anisotropic rare earth sintered magnet material, and is characterized by considering the characteristics of various recovered scraps and focusing on the maximum scrap recovery and reuse.

The recovered rare earth sintered magnet of the present invention is a so-called Nd-based sintered magnet, but is characterized in that SmCo-based sintered magnets that are used in some markets and are available as recovered scrap can also be used as raw materials.

More preferably, neodymium sintered magnet collection waste or a mixture of neodymium sintered magnet collection waste and samarium cobalt sintered magnet collection waste is used.

That is, although it is manufactured from the recovered rare earth anisotropic sintered magnet, the maximum energy product (BH) max is 96 to 270 kJ / m ³ equal to or higher than that of the conventional anisotropic rare earth bonded magnet. In order to produce an anisotropic rare earth bonded magnet having magnetic properties, the composition of the magnet is at least 13 to 35 wt% of neodymium (Nd) and 0.3% of boron (B) as components other than iron (Fe). ~ 1.3wt%, Samarium (Sm) 0 ~ 30wt%, Cobalt (Co) 0 ~ 15wt%, Nickel (Ni) 0 ~ 5.5wt%, Aluminum (Al) 0 ~ 5.5wt% It is necessary that nickel (Ni) and aluminum (Al) are included and 0.3 wt% or more is included.

Preferably, an anisotropic rare earth bonded magnet having a magnetic property with a maximum energy product (BH) max of 170 to 270 kJ / m ^{3. In} order to manufacture the magnet, the composition of the magnet is other than iron (Fe). As components, at least neodymium (Nd) is 17 to 33 wt%, boron (B) is 0.55 to 1.25 wt%, samarium (Sm) is 0 to 14 wt%, cobalt (Co) is 0 to 13 wt%, nickel ( Ni) must be 0 to 4.9 wt%, aluminum (Al) should be 0 to 4.8 wt%, and nickel (Ni) and aluminum (Al) must be combined to contain 0.3 wt% or more. It is.

More preferably, it is an anisotropic rare earth bonded magnet having a magnetic property with a maximum energy product (BH) max of 205 to 270 kJ / m ³ , and in order to produce it, the composition of the magnet is other than iron (Fe). At least 20-30 wt% neodymium (Nd), 0.8-1.1 wt% boron (B), 0-8 wt% samarium (Sm), 0-8 wt% cobalt (Co), nickel (Ni) contains 0 to 3.5 wt%, aluminum (Al) contains 0 to 3.5 wt%, and nickel (Ni) and aluminum (Al) together contain 0.3 wt% or more. is necessary.

In the present invention, since the recovered rare earth sintered magnet is used as a raw material, it is usually provided with an AL coating and Ni-coating, so that Al and Ni components are usually combined with nickel (Ni) and aluminum (Al). .3 wt% or more, and in some cases, 1 wt% or more. Even if the content of Al or Ni is up to 5.5% by weight, sufficient magnetic properties can be exhibited.

The magnet of the present invention includes components other than Fe, Nd, B, Sm, Co, Ni, and Al, and usually the components have the following composition (wt%).
Nd; 13-35, Pr; 0-10, Dy; 0-12, Tb; 0-3, Sm; 0-30, Ce; 0-10, B; 0.3-1.3, Co; 0- 15, Nb; 0-1.5, Cu; 0-10, Al; 0-5.5, Ga; 0-1.5, Ni0-5.5, Zr; 0-0.5, Hf; 0- 0.5, Fe; balance.

A desirable composition (wt%) for realizing higher magnetic properties is as follows.
Nd; 17-33, Pr; 0-5, Dy; 0-9, Tb; 0-2, Sm; 0-14, Ce; 0-3, B; 0.55-1.25, Co; 0- 13, Nb; 0-0.8, Cu; 0-8, Al; 0-4.8, Ga; 0-0.8, Ni; 0-4.9, Zr; 0-0.3, Hf; 0-0.3, Fe; balance.

A desirable composition (wt%) for realizing higher magnetic properties is as follows.
Nd; 20-30, Pr; 0-3, Dy; 0-7, Tb; 0-1, Sm; 0-8, Ce; 0-1, B; 0.8-1.1, Co; 0- 8, Nb; 0-0.6, Cu; 0-7, Al; 0-3.5, Ga; 0-0.2, Ni; 0-3.5, Zr; 0-0.3, Hf; 0-0.2, Fe; balance.

Nd is an important essential element for obtaining excellent magnetic properties, and the most excellent magnetic properties can be realized when Nd is 20 to 30 wt%.

The magnet scrap of the present invention is most preferably composed only of Nd magnet scrap in order to exhibit higher magnetic performance, but high magnetic performance even if the Nd magnet scrap contains SmCo-based magnet scrap. It is possible to demonstrate. However, as the blending ratio of SmCo sintered magnet scrap increases, the magnetic properties such as residual magnetic flux density Br and maximum energy product (BH) max that are obtained at that time monotonously decrease. The Sm content is limited.

That is, one of the features of the present invention is that excellent magnetic properties can be realized even in a composition region containing Sm that cannot be realized by a normal Nd-based anisotropic bonded magnet. Even Sm content up to 6 wt% is possible. If it exceeds 6 wt%, the magnetic properties will gradually deteriorate.

Here, the major difference between the normal Nd magnet composition and the raw material scrap is the Sm, Co, and Cu contents, which are outside the normal composition of the Nd magnet. This is characterized by the fact that the entire amount or most of the city waste is SmCo-based, and that it is possible to newly recover the waste that is impossible with the conventional remelting and alloying methods. .

In addition, an anisotropic rare earth bonded magnet excellent in the method of the present invention can be obtained without any problem without removing the resin from the epoxy resin coated product.

The anisotropic rare earth bonded magnet of the present invention uses the magnet collected as described above as it is without pretreatment, removal of impurities, etc., so that a relatively high ratio of O (oxygen) amount, C (carbon) amount Even in this case, it has a performance equal to or higher than that of conventional isotropic bonded magnets and anisotropic bonded magnets.

Conventional material alloys for anisotropic rare earth bonded magnets have limited amounts of impurities O (oxygen) and C (carbon) in order to obtain excellent magnetic properties. When there is much O and C, a magnetic characteristic will fall remarkably. An anisotropic rare earth bonded magnet is a high purity rare earth metal, iron, boron and other essential elements are all made of high purity raw materials. Therefore, a magnet alloy dissolved and refined using these materials has an O content of at least 0.08 wt%, usually less Is 0.01 wt% or less, and the C content is at least 0.03 wt% or less, usually 0.05 wt%.

On the other hand, since the raw material alloy of the anisotropic rare earth bonded magnet of the present invention uses the recovered rare earth anisotropic sintered magnet, the amount of O and C increased due to oxidation and binder addition during the sintered magnet manufacturing process. The amount of O is at least 1 wt%, usually 4 wt% or more, and the amount of C is 0.4 wt% or more, usually 0.5 wt% or more.

However, depending on the state of the recovered material, the magnet may be significantly oxidized and corroded, or there may be recovered scraps that are markedly adhered with adhesive or coated when the magnet is recovered, and these have sufficient magnetic properties. Absent. Therefore, in order for the anisotropic rare earth bonded magnet of the present invention to maintain a magnetic property having a maximum energy product (BH) max of 96 kJ / m ³ or more, the upper limit of the O amount is 8 wt% or less, and preferably 5 wt% or less. , C content is required to be 7 wt% or less, preferably 4 wt% or less.

The anisotropic rare earth bonded magnet of the present invention is equivalent to or more than conventional isotropic bonded magnets and anisotropic bonded magnets even if a raw material having a high amount of O, C as impurities, which is normally unusable, is used. One of the features is that it has excellent magnet characteristics, heat resistance characteristics, and corrosion resistance.

And the anisotropic rare earth bonded magnet of the present invention is characterized by its magnet structure in order to obtain excellent magnetic properties. Specifically, the average particle size of the magnet powder constituting this magnet is 30 to 200 μm, more preferably 50 to 170 μm, and the average crystal particle size of the main phase forming each particle is a conventional anisotropic rare earth. An anisotropic rare earth bonded magnet having a microstructure that is completely different from that of the bonded magnet, that is, 1 to 15 μm, more desirably 1.5 to 10 μm, most preferably 2.0 to 7.0 μm.

The coercive force of rare earth magnets is reduced due to a multi-domain structure when the crystal grain size is large, and the coercive force decreases due to oxidation or processing strain, although it is a single domain structure when the crystal grain size is small. Therefore, there is an optimal crystal grain size that depends on the magnet process.

The average crystal grain size of the main phase forming each particle of the anisotropic rare earth bonded magnet of the present invention has a structure of 1 to 15 μm (micron) completely different from the grain size of the conventional anisotropic rare earth bonded magnet. In order to obtain an excellent high coercive force and to suppress the oxygen content, 1.5 to 10 μm, more preferably 2.0 to 7.0 μm is most desirable. Here, the main phase is Nd ₂ Fe ₁₄ B intermetallic compound phase in the case of Nd-based recovered scrap, and SmCo ₅ or Sm ₂ (Fe, Co, Cu) ₁₇ intermetallic compound phase is main in the SmCo system. Is a phase. The volume ratio of the main phase is 90% or more of the entire magnet.

The average particle size of the magnet powder is a condition from the manufacturing conditions of the bonded magnet in consideration of high density and productivity. On the other hand, since this magnet is essentially a recovered scrap material, it has an average crystal grain size of submicron or less obtained by a rapid cooling process (so-called melt spinning) such as a conventional nanocomposite or MQI powder or a HDDR manufacturing method. It is essentially different from the bond magnets that it has, and because of the Nd-based material, it has a completely different magnet composition from the SmFeN bond. Incidentally, typical average grain sizes of MQI powder, HDDR, and SmFeN are 0.05 μm, 0.3 μm, and 0.4 μm, which are extremely smaller than 1 to 15 μm of the average crystal grain size of the magnet of the present invention. The characteristics of the magnet according to the present invention make the best use of the characteristics of the recovered scrap raw material, and at the crystal grain size that has not been realized in the past, magnetic characteristics equivalent to or higher than those of conventional anisotropic rare earth bonds can be obtained. It has been found that it can be.

Here, the average particle size measurement is a value measured by a hole permeation method (Fischer, subseed sizer, etc.), and the crystal particle size is a crystal particle size derived by image analysis of a two-dimensional metal structure photograph. The pore permeation method, commonly called the Fischer method (FSSS), is a general industrial method in which pressurized air is permeated through a sample and the average particle size is measured based on a certain conversion formula from the pressure drop after permeation. . Specifically, the image analysis is performed by a so-called cutting method in which five vertical and horizontal straight lines are drawn at a pitch of 10 μm in a visual field of a 50 μm region of a metal structure photograph at a magnification of 400 times and the length (L) of the slice is obtained by the following formula. It is determined from the nominal crystal grain size (d).
(Formula) d = 1.128L

Then, the manufacturing method of an anisotropic rare earth bond magnet is demonstrated.

The method for producing an anisotropic rare earth bonded magnet using the rare earth anisotropic sintered magnet of the present invention as a raw material includes a step of mechanically crushing the rare earth anisotropic sintered magnet in an inert atmosphere, It consists of a step of strain relief annealing at a temperature of 400 to 600 ° C. in a vacuum or an inert atmosphere and a holding time of 12 hours or more, and a step of kneading the strain relief annealed material and a binder to form a magnetic field. It is characterized by.

As the rare earth anisotropic sintered magnet as a raw material for the anisotropic rare earth bonded magnet according to the present invention, the anisotropic rare earth sintered magnet recovered scrap recovered from the market as described above can be used.

In order to obtain the desired maximum energy product (BH) max, it is preferable to perform component analysis and magnetic property measurement of magnet recovery scrap.

That is, in order to produce an anisotropic rare earth bonded magnet having any desired magnetic property with a maximum energy product (BH) max in the range of 96 to 270 kJ / m ³ , the collected rare earth sintered magnet is sampled in advance. Then, it is preferable to conduct a component analysis of the recovered magnet material and confirm the composition of neodymium (Nd) and samarium (Sm) as the composition of the magnet. Judging from the analysis value, in order to obtain a desired magnetic characteristic, a bonded magnet can be prepared by further blending and adjusting magnet scraps with other components already known. However, for that purpose, it is preferable to accumulate data of CR values, which will be described later, with various collected scraps.

In addition, when the recovered rare earth anisotropic sintered magnet is a single magnet scrap, this component analysis can be omitted. In particular, the recovered rare earth anisotropic sintered magnet is a mixture of various kinds. Is essential, and it is preferable that the number of sampling is large.

Note that the magnetic characteristics of the sintered magnet before being discarded can be set as representative magnetic characteristics, for example, when n = 3 to 10 samples are collected, for example, when the collected waste is mixed municipal waste. Similarly, the magnetic scrap component analysis can also be performed by n = 3 to 10 sampling analysis by ICP or the like. In addition, the magnetic characteristic and the numerical value of component analysis which are shown in the examples are performed with n = 3.

It is also possible to mix and use one or more kinds of scraps according to the obtained component analysis values and magnetic characteristics. Desirably, the rare earth anisotropic sintered magnet as a raw material is preferably a neodymium sintered magnet recovery scrap or a mixture of neodymium sintered magnet recovery scrap and samarium cobalt sintered magnet recovery scrap.

In addition, when samarium (Sm) is detected by 30% by weight or more by component analysis, an excellent anisotropic rare earth bonded magnet having a higher mixing ratio of the samarium cobalt sintered magnet and higher magnetic characteristics than that of the Nd magnet base. This material is not suitable for the production of

That is, when 30% by weight or more of samarium is detected as a result of component analysis in the collected rare earth anisotropic sintered magnet and the samarium-cobalt sintered magnet is mixed in a lot, the corresponding recovered scrap is replaced with other Nd magnet-based recovered scrap. Used by diluting and mixing.

In this collection process, in order to make effective use of the recovered rare earth sintered magnet material and process it in the optimal manufacturing process to exhibit the maximum anisotropic rare earth bonded magnet magnetic properties, component analysis of the magnet material used is It is essential.

Component analysis is based on ICP or X-ray fluorescence analysis. For the same reason, it is essential to measure the magnetic properties of the recovered raw material. In order to exhibit the required magnetic properties, it is possible to use one or more kinds of magnet material scraps in combination, which is a feature of this manufacturing method. This is because it is necessary to evaluate the waste performance by component analysis and magnetic property measurement, and to optimize and obtain the maximum maximum energy product (BH) max by adjusting the selection and mixing of the waste to be used according to the application.

The steps of the method for producing an anisotropic rare earth bonded magnet using the rare earth anisotropic sintered magnet as a raw material will be described in detail below.

First, the collected magnets are crushed. The pulverization can be performed by mechanical pulverization such as a ball mill, an attritor, and a jaw crusher. A two-stage treatment such as grinding with a jaw crusher and then finely grinding with a ball mill is also effective, the particle size distribution can be made uniform, and the magnetic properties can be improved. In order to prevent oxidation, the grinding atmosphere is performed in an inert atmosphere such as Ar or N or in a solvent such as alcohol or acetone.

本 The recovered waste uses a crushing process that does not require any hydrogen crushing, which is essential in the conventional magnet manufacturing process. This is because when hydrogen pulverization is used, microcracks are generated during press molding, and magnetic properties are deteriorated due to significant oxidation of the powder.

For fine pulverization, general ball mill pulverization or the like is used. However, since the raw material used is a rare-earth sintered magnet, which is a microcrystalline and extremely hard alloy, it is not a conventional high speed ball mill of 2 to 6 hours, but a low speed ball of 12 to 24 hours Using the process has higher magnetic properties.

The average particle size of the pulverized powder is 30 to 200 μm, more preferably 50 to 170 μm, in order to obtain high magnetic properties.

As will be described later, it is also effective to use two kinds of powders having different particle sizes in order to improve the magnetic properties by increasing the packing density during press molding. In particular, it is important to improve molding conditions such as using two types of powders with poor moldability.

One of the features of this magnet manufacturing process is a process that does not use hydrogen crushing. Hydrogen crushing is a production method that is often used because Sm magnets and Nd magnets have inherently hydrogen storage and hydrogen embrittlement, but the rare earth scrap recovery industry can disseminate a large amount of processing safely and inexpensively as a social scheme. In order to make the proposal as versatile as possible, a process that does not use any hydrogen pulverization process is proposed. Of course, the pulverization method by hydrogen pulverization is not excluded.

This magnet powder must be heat-treated in a high vacuum or inert atmosphere after grinding. If heat treatment is not performed, the coercive force value HCJ obtained is extremely low at 800 kA / m (10 kOe) or less, as shown in the prior patent (Japanese Patent Application No. 4-303254), and the heat resistance of the magnet is low.

The heat treatment temperature is 400 to 600 ° C., but a heat treatment time of 12 hours or longer, preferably 48 hours or longer, is desired. If the temperature exceeds 600 ° C., the powder is welded and further diffusion occurs. Therefore, if possible, the temperature is preferably 500 ° C. or lower. At a low temperature of 400 ° C., it takes a long time for heat treatment to remove strain, and it is preferably 24 hours or more or 48 hours or more.

The purpose of this heat treatment for strain relief is to anneal inevitable mechanical strains such as microcracks generated during mechanical crushing. However, in order to prevent oxidation of magnet powder during heat treatment, getter powder such as Ti, Ca, Mg, etc. is used for each sample container. It is desirable to insert it into

The magnet molding process is not particularly limited, and may be compression molding or injection molding. Specifically, for example, the obtained powder is first kneaded with a binder. As the binder, an epoxy resin is used in compression molding, and a thermoplastic resin such as PA resin (nylon 12 or the like) or heat-resistant PPS is used in injection molding. In order to maintain high magnetic properties, it is necessary to suppress the amount of the binder to the lower limit addition amount that does not impair the moldability, and is 3-7 wt% for compression molding and 5-10 wt% for injection molding. In addition, an antioxidant, a stearic acid-based mold lubricant, and the like may be added in an amount of 0.8 wt% or less depending on the product shape.

In compression press molding, a magnetic field press method can be adopted, and molding corresponding to a magnet shape such as right-angle molding, parallel molding, radial molding, and diameter dipole molding is possible. The molding pressure is 0.9 Ton / cm ² or more, preferably 6.5 Ton / cm ² or more, more preferably 8.5 Ton / cm ² or more in order to realize high magnetic properties by increasing the molding density.

In the magnet molding process, a method of magnetic field molding using powders having two or more types of particle sizes is also effective, but this method is extremely effective in this raw material alloy system, and the average particle size ratio Cp of the two types of powders to be mixed is Cp. = Excellent magnetic properties when using powder having 0.1 to 0.3. Desirably, Cp = 0.15 to 0.25.

Also, when the mixing ratio Kp of these two kinds of powders is kneaded to Kp = 1.5 to 4.0, the density is increased and high excellent magnetic properties are obtained. Kp is more preferably Kp = 2.0 to 3.5. Kp is (coarse particle weight) / (microparticle weight). The conditions of the present Cp and Kp are the same in the injection molding press.

In this embodiment, wet molding that is easy to increase the density of the molded body is also an extremely effective method. Although the wet molding method is already used in the production method of rare earth sintered magnets, it is usually used at a higher cost than the dry process and requires a solvent removal process during sintering. There are no prior art papers reported as molding methods. In the present embodiment, it has been found that this wet molding is extremely effective.

In the present embodiment, two-stage press molding in which cold isotropic pressing (hereinafter referred to as CIP) is further performed following compression molding or wet molding may be employed. This is because it is effective to increase the magnetic properties by increasing the density of the molded body by applying a high molding pressure by CIP. The pressure at which CIP is effective is 200 MPa or more, desirably 300 MPa or more. The CIP medium is a solvent such as glycerin, and the CIP pressure application time is 10 to 20 minutes.

Wet press molding mainly contributes to densification by improving the coefficient of friction on the mold surface, and CIP contributes differently to densification by hydrostatic pressure from all directions, so a combination of wet molding and CIP. A multi-stage press having various effects is effective. These powder moldings are unique to the powder physical properties such as mechanical properties and particle size distribution of rare earth sintered dust powder, which are hardly manifested in the effects of conventional rare earth sintered magnets.

The solvent used for the wet molding can be an organic solvent such as alcohol or acetone, lubricating oil, gasoline or the like. By magnetic field molding under these solvents, the press molding pressure can be reduced by 20-30% from the usual dry pressure, and peeling, cracking, chipping, etc. during molding are remarkably improved. Wet molding essentially requires an inevitable solvent removal step, but it is extremely effective molding because it is not necessary at all in the proposed anisotropic rare earth bonded magnet manufacturing method.

Also, in the press magnet manufacturing method, in order to increase the density, a powder filling tapping process such as air tapping and ultrasonic tapping during the magnetic field forming process obtains a high tap density and is extremely effective as a molding technique for this powder. Tapping is performed by propagating the pressure vibration of the compressed air, such as by attaching a vibration transmission board to a magnetic mold. Alternatively, the density is increased by inserting a green molded body previously air-tapped in a temporary press package into a mold.

A magnet obtained by compression molding or injection molding can be used as a product as it is, but by applying Ni plating, epoxy coating, etc., it can be applied to applications requiring corrosiveness and corrosion resistance. By carrying out these surface treatments, although they are manufactured from the collected rare earth anisotropic sintered magnet, they have corrosion resistance reliability equivalent to or higher than that of commercially available anisotropic rare earth bonded magnets. Specifically, the corrosion resistance evaluation is performed under the condition of 80 ° C. × 90% RH.

The above anisotropic rare earth bonded magnet manufacturing method realizes an energy product with a maximum energy product (BH) max of 96 to 270 kJ / m ³ and a high standard squareness ratio p0.70, and further, based on the analysis value By selecting the magnetized scraps, it is possible to realize excellent magnetic properties that exceed the conventional anisotropic rare earth bonded magnet having a coercive force HcJ of 800 kA / m or more.

In the present invention, since the purpose is to reuse the rare earth sintered magnet to be discarded, it is not necessary to ensure the reproducibility of the magnetic properties originally possessed by the magnet material before the disposal, but the discarded magnet material. Depending on the form, impurities, and the presence or absence of coating, etc., the magnetic material having one or several steps (cascade) magnetic properties will be embodied and used effectively, but the magnetic force is still the conventional isotropic rare earth It has performances higher than those of bonded magnets and anisotropic rare earth bonded magnets.

Here, the definition of the CR rate shown in the examples is shown below.

The maximum energy product of sintered magnets before disposal is α, and the maximum energy product (β) of manufactured anisotropic rare earth bonded magnets, CR ratio = β / α

In the present invention, the CR rate is usually 0.3 to 0.7. The upper limit of the CR rate is 0.7 because the recovered magnet is simply pulverized without pretreatment, and the upper limit is usually 0.75. The lower limit is usually 0.30 or more, preferably 0.45, more preferably 0.55 or more in terms of magnet cost / magnetic performance. When the CR ratio is 0.3 or less, the cost merit is small compared to a normal commercially available isotropic rare earth bonded magnet.

By realizing an energy product with a maximum energy product (BH) max of 96 to 270 kJ / m ³ and a high standard squareness ratio p0.70, and selecting sintered magnet debris based on the analysis value, the coercive force HcJ is Excellent magnetic characteristics of 800 kA / m or more can be realized. This indicates that the heat resistance, which is extremely important in practical use of the permanent magnet, specifically, the heat demagnetization property is sufficiently high.

Generally, in order to improve the thermal demagnetization characteristics of a permanent magnet, it is necessary that the coercive force HcJ and the squareness Hk of the demagnetization curve are large. Here, Hk is defined as the value of the magnetic field H at which the value of magnetization J is 90% of the residual magnetic flux density (Br) on the JH demagnetization curve. However, since the squareness Hk value differs depending on the material of the permanent magnet, it is necessary to standardize and evaluate the numerical value. In the present invention, the value normalized by the coercive force HcJ and the normalized squareness ratio p are used for convenience. It defines and uses by p = Hk / HcJ.

The main reasons why the thermal demagnetization characteristics of the present anisotropic rare earth bonded magnets are still insufficient in practical use are that the coercive force HcJ is low and the normalized squareness ratio p value is low. At present, there are two types of anisotropic rare earth bonded magnets: an HDDR type magnet using a process called HDDR or d-HDDR and an SmFeN type produced by nitriding an SmFe alloy. Neither of these HDDR type anisotropic rare earth bonded magnets nor SmFeN type anisotropic rare earth bonded magnets have a high coercive force HcJ and a high normalized squareness ratio p value comparable to those of sintered magnets.

Especially, the normalized squareness ratio p-value that greatly affects the thermal demagnetization characteristics is largely attributable to the magnet manufacturing process and uniformity. With HDDR magnets, it is very difficult to make anisotropy technology in which crystal grains are oriented in the same direction during the resorption process (desorption), and even for SmFeN, nitrogen diffuses uniformly from the surface to the SmFe alloy. The reaction technique is very difficult, and a high normalized squareness ratio p has not been obtained.

On the other hand, rare earth sintered magnets are magnetically molded from finely pulverized powder of several microns, so that the degree of crystal grain orientation is extremely high, and the average grain size of the powder particles of the present invention is the conventional one. Since the grain size of anisotropic rare-earth bonded magnets is completely different from 30 to 200 microns, which is much larger than the original crystal grains, a high normalized squareness ratio p can be realized relatively easily without disturbing the degree of crystal grain orientation. Is possible. The magnet of the present invention is an anisotropic rare earth bonded magnet having a normalized pragmatic ratio of 0.70 or more and a maximum of 0.90 or more even in a normal process and having an extremely high p value, ie, excellent temperature characteristics such as thermal demagnetization. . In order to have excellent heat resistance, it is essential that the normalized squareness ratio p is high in addition to high coercivity.

Since the present invention is characterized by using an anisotropic rare earth sintered magnet raw material as a raw material in this way, the coercive force is substantially higher than that of a conventional anisotropic rare earth bonded magnet and a high p value is obtained. can get.

The coercive force HcJ of current commercially available anisotropic rare earth bonded magnets is 1,100 to 1,500 kA / m, the normalized squareness ratio p is 0.2 to 0.3, and at most 0.4. The heat resistance of the isotropic rare earth bonded magnet, specifically, thermal demagnetization is about 120 to 140 ° C.

On the other hand, the anisotropic rare earth bonded magnet of the present invention has a maximum coercive force HcJ of 2,000 kA / m, a normalized squareness ratio p of 0.70-0.85 even in a normal process, and a maximum of 0, which is the same as a sintered magnet. .90 or more is possible. According to the magnet of the present invention having excellent characteristics such as a coercive force of 2,000 kA / m and a normalized squareness ratio p of 0.85, heat resistance can be realized at 140 ° C. or 180 ° C. even at a maximum of 200 ° C. It is. Since the anisotropic sintered magnet material having extremely high squareness is used as a raw material, the magnet of the present invention is essentially a highly heat-resistant anisotropic rare earth bond having a normalized squareness ratio p. It becomes a magnet.

Thus, one of the greatest characteristics of the anisotropic rare earth bonded magnet of the present invention is heat resistance, specifically, thermal demagnetization characteristics.

熱 Thermal demagnetization characteristics are evaluated by the amount of decrease in magnetic flux after a long period of time (usually 1000 hours) at a certain Pc (permeance coefficient, usually Pc = 1 or 2). The heat resistance is evaluated at the highest temperature at which the standard for the amount of magnetic flux reduction is normally 5%. It is said that the heat resistance of anisotropic rare earth bonded magnets is usually about 120 ° C because the decrease in magnetic flux after 1000 hours is 5% at 120 ° C, so this 120 ° C temperature can be used in practice. It means that it is the upper limit temperature.

The heat resistance of currently available anisotropic rare earth bonded magnets is about 120-140 ° C. For example, anisotropic SmFeN bonded magnets are reported to be 130 ° C. at the maximum for mass production and 150 ° C. at the research level. (For example, Japan Bond Magnetic Materials Association, BMNews, No43, 2010).

The present invention is basically a Nd-based material system because the Nd magnet recovered scrap contained in the recovered scrap is a large amount in the market, and its heat resistance is normally 140 ° C., more than 180 ° C. An anisotropic rare earth bonded magnet having temperature characteristics. That is, the heat resistance exceeding 120-140 ° C. of the conventional anisotropic rare earth bond is obtained.

Specifically, the present invention is such that Pc = 2, thermal demagnetization is 5% or less under the condition of 140 ° C. × 1000 hr, further exceeds 160 ° C. under the same conditions, and the recovered waste is sorted and used, and the magnetic powder such as the kind of binder and the added amount By selecting the production conditions other than those, extremely excellent heat resistance exceeding 180 ° C. can be provided.

On the other hand, it is known that the thermal demagnetization characteristics of anisotropic rare earth bonded magnets by the α-HDDR manufacturing method currently on the market are as large as Pc = 2, 150 ° C. × 1000 hr and thermal demagnetization of about 11%. .

Another feature of the magnet performance of the anisotropic rare earth bonded magnet of the present invention is high corrosion resistance, and that this magnet has long-term reliability and stability that can be sufficiently applied for long-term use. .

This magnet obtained by compression molding or injection molding can be used as a product as it is, but by applying surface treatment such as Ni plating, epoxy coating, etc., it has higher corrosion resistance than that of the usual anisotropic rare earth bonded magnets. Reliable. Corrosion resistance evaluation is performed under the condition of 80 ° C. × 90% RH which is usually performed, and it is known that an anisotropic rare earth bonded magnet material has a limit of corrosion resistance for 200 to 400 hours.

The anisotropic rare earth bonded magnet of the present invention has a corrosion resistance under 80 ° C. × 90% RH condition for about 300 hours or more. Furthermore, by performing sufficient surface treatment, it is possible to have excellent corrosion resistance with no change in appearance up to 500 hours.

When converted to reference for life prediction estimated from the accelerated corrosion test of temperature and humidity, 80 ° C. × 90% RH × 500 hours is, for example, 23.8 ° C. × 78% RH, about 20 years, 16.2 ° C. × 67% RH, corresponding to about 115 years, it can be seen that this anisotropic rare earth bonded magnet has practically sufficient long-term corrosion resistance and long-term reliability.

It is known that a commercially available anisotropic bonded magnet material has a limit of 200 to 400 hours in corrosion resistance. The anisotropic bonded magnet according to the present invention is a magnet having excellent long-term corrosion resistance and long-term reliability with no change in appearance for up to 500 hours by applying a sufficient surface treatment for about 300 hours equivalent to or longer than these. Is possible.

<Example 1>
Measurement of the magnetic properties and ICP component analysis (n = 3) of the municipal waste recovered as the starting material gave the following properties and analysis values (Table 1-1, Table 1-2). The analytical values of the amount of O and C of the recovered waste were 4.3 wt% and 0.8 wt%, respectively. The average crystal grain size was 6.2 μm as measured by n = 5. This alloy powder was ball milled in acetone to obtain a press-molded powder. The average particle size is 75 μm. The obtained powder was heat-treated in a high vacuum containing a Ti getter material at 550 ° C. × 24 hours, and then kneaded by adding 4.5 t% of an epoxy binder to this molded powder to obtain a compound. After compression molding at / cm ² , CIP treatment is further performed at a pressure of 300 MPa for 10 minutes. The obtained anisotropic bond magnetic properties and the magnetic properties (n = 5) of the collected magnets are shown below together with the measured average magnetic properties. The recovered scrap was a component of the Nd magnet alone, and the CR obtained was 0.64.

<Example 2>
Measurement of the magnetic properties and ICP component analysis (n = 3) of the municipal waste recovered from the starting material gave the following properties and analysis values (Tables 2-1 and 2-2). The analytical values of the O amount and the C amount of the recovered waste were 4.8 wt% and 0.9 wt%, respectively. The average crystal grain size was 8.2 μm as measured by n = 5. This alloy powder was ball milled in acetone to obtain a press-molded powder. The average particle size is 51 μm. The obtained powder was heat treated in a high vacuum containing a Ti getter material at 550 ° C. × 24 hr, and then kneaded by adding 4.5% of an epoxy binder to the molded powder to obtain a compound of 4.0 Ton / cm ^2. Then, CIP treatment is performed at a pressure of 300 MPa for 10 minutes.

The recovered waste was a component containing a part of Nd magnet and Sm, and CR obtained was 0.69.

<Example 3>
Measurement of the magnetic properties and ICP component analysis (n = 3) of the municipal waste recovered from the starting material gave the following properties and analytical values (Tables 3-1 and 3-2). The analytical values of the O amount and C amount of the recovered waste were 3.5 wt% and 2.4 wt%, respectively. The average crystal grain size was 9.5 μm by n = 5 measurement. This alloy powder was ball milled in acetone to obtain a press-molded powder. The average particle size is 85 μm. The obtained powder was heat-treated in a high vacuum containing a Ti getter material at 550 ° C. × 24 hr, and then kneaded by adding 6.5 wt% of nylon 12 binder to this molded powder to obtain a compound, and injection molding in a magnetic field did. The CR derived from the magnetic properties of the recovered magnet of the obtained anisotropic bond magnetic properties was 0.47.

This recovered waste is a component containing a part of Nd magnet and Sm, but the content of SmCo magnet is larger than that in Example 2, and the obtained CR was 0.47.

<Example 4>
Measurement of the magnetic properties and ICP component analysis (n = 3) of the municipal waste recovered from the starting material gave the following properties and analysis values (Tables 4-1 and 4-2). The analytical values of the amount of O and the amount of C of the collected waste were 6.9 wt% and 3.2 wt%, respectively. The municipal waste used was almost entirely recovered from Ni-plated products. The average crystal grain size was 7.0 μm as measured by n = 5. This alloy powder was first roughly pulverized with a jaw crusher and then finely pulverized in acetone to obtain a press-molded powder. The average particle size is 63 μm. The obtained powder was heat-treated in a high vacuum containing a Ti getter material at 550 ° C. × 24 hr, and then kneaded by adding 4.5 t% of an epoxy binder to this molded powder to obtain a compound, 3.5 Ton / cm ² Then, CIP treatment is performed at a pressure of 300 MPa for 10 minutes.

In order to verify the effect of air tapping, air tapping using compressed air is performed at the time of magnetic field molding, the green density before molding is increased and then molded, and after further compression molding, CIP treatment is performed for 10 minutes at a pressure of 300 MPa. An anisotropic bonded magnet was prepared.

The collected waste was a component of the total amount of Nd magnet waste.

It was found that CR of the obtained anisotropic bond magnetic property was 0.61, and CR improved to 0.68 when air tapping was performed. It was confirmed that good magnetic properties were obtained for the Ni-plated recovered scrap regardless of the presence or absence of air tapping.

<Example 5>
Measurement of the magnetic properties and ICP component analysis (n = 3) of the municipal waste recovered from the market as starting materials gave the following properties and analysis values (Tables 5-1 and 5-2). The analytical values of the O amount and C amount of the recovered waste were 5.8 wt% and 1.8 wt%, respectively. The average crystal grain size was 8.7 μm as measured by n = 5. This alloy powder was ball milled in acetone to obtain a press-molded powder. The average particle size is 95 microns. The obtained powder was heat-treated in a high vacuum containing a Ti getter material at 550 ° C. × 24 hr, then kneaded by adding 6.5 t% of PPS binder to this molded powder, and obtained by injection molding in a magnetic field. . Reliability was also confirmed by applying an epoxy spray coating after molding.

The recovered waste was a component containing a part of Nd magnet and Sm, and CR obtained was 0.49.

Further, the corrosion resistance and reliability of the magnet of the present invention were evaluated together with a commercially available SmFeN anisotropic bonded magnet (Table 5-3). After obtaining the commercially available SmFeN anisotropic bonded magnet of the comparative example, it was processed under the same epoxy spray coating conditions as the magnet of the present invention. When the corrosion resistance was tested under the conditions of 80 ° C. × 90% RH, the commercially available SmFeN red spot rust-generating magnet already generated minute red spot rust in 300 hours, while the magnet of the present invention did not generate rust until 600 hours. It has been found that it has long-term corrosion resistance and long-term stability that are significantly better than isotropic bonded magnets. This is presumed to be because the raw material used is a sintered magnet having a fine and uniform structure, so that corrosion from the crystal grain boundaries and the internal progress thereof are very unlikely to occur.

<Example 6>
Measurement of the magnetic properties and ICP component analysis (n = 3) of the municipal waste recovered as the starting material gave the following properties and analytical values (Tables 6-1 and 6-2). The analytical values of the amount of O and the amount of C of the collected waste were 4.1 wt% and 2.6 wt%, respectively. Some of the Nd magnets were mostly recovered scrap from Al (aluminum) surface treatment. The average crystal grain size was 6.3 μm as measured by n = 5. This alloy powder was ball milled in acetone, and a press-molded powder was obtained by sampling during grinding. Each average particle size is 14,59 μm. (Cp = 0.24) These obtained powders were heat-treated in a high vacuum containing a Ti getter material at 550 ° C. × 24 hr, and these two powders were blended and mixed at Kp = 2.0. An epoxy binder is added in an amount of 4.5 wt% and kneaded to obtain a compound, which is compression-molded in a magnetic field at 4.0 Ton / cm ² , and then CIP-treated at a pressure of 300 MPa for 10 minutes. The CR of the obtained anisotropic bonded magnetic property was 0.43, and the recovered scrap was an Al surface-treated Nd magnet and partly SmCo magnet, but good anisotropic bonded magnet magnetic properties were obtained. ing.

In order to compare the thermal demagnetization characteristics of the obtained anisotropic bonded magnet, it was compared with a commercially available isotropic bonded magnet and anisotropic bonded magnet (Table 6-3). The thermal demagnetization evaluation condition is Pc = 2, 1,000 hours at a holding temperature of 140 ° C. or 180 ° C. As shown in this table, it can be seen that the magnet of the present invention achieves a very low thermal demagnetization amount of 1.8% at 140 ° C. and 3.6% at 180 ° C. On the other hand, in the commercially available isotropic and anisotropic magnets of the comparative examples, the amount of thermal demagnetization is extremely large at any temperature of 140 ° C. and 180 ° C., and the magnet of the present invention has an excellent heat resistant use temperature. I understand that. This reason is presumed to be largely attributable to the fact that the recovered sintered magnet scrap used is a magnet component having high heat resistance such as Dy and Tb as can be seen from the component analysis results.

<Example 7>
Measurements of magnetic properties and ICP component analysis (n = 3) of the municipal waste recovered from the starting materials were performed, and the following properties and analysis values were obtained (Tables 7-1 and 7-2). The analytical values of the O amount and C amount of the recovered waste were 3.7 wt% and 2.1 wt%, respectively. The average crystal grain size was 7.2 μm as measured by n = 5. This alloy powder was ball milled in acetone to obtain a press-molded powder. The average particle size is 58 μm. The obtained powder was heat-treated in a high vacuum containing a Ti getter material at 550 ° C. × 24 hr, and then kneaded by adding 4.5 wt% of an epoxy binder to this molded powder to obtain a compound, which was further mixed with an inorganic solvent. Then, after wet compression molding at 4.0 Ton / cm ² in a magnetic field, CIP treatment is further performed at a pressure of 300 MPa for 10 minutes. The CR of the obtained anisotropic bond magnetic property was 0.62.

In order to compare the thermal demagnetization characteristics of the obtained anisotropic bonded magnet, it was compared with a commercially available isotropic bonded magnet and anisotropic bonded magnet (Table 7-3). The thermal demagnetization evaluation condition is Pc = 2, 1,000 hours at a holding temperature of 140 ° C. or 180 ° C. As shown in this table, it can be seen that the magnet of the present invention achieves a very low thermal demagnetization amount of 2.3% at 140 ° C. and 4.2% at 180 ° C. On the other hand, the anisotropic SmFeN bonded magnet of the comparative example has an extremely large amount of thermal demagnetization at both 140 ° C. and 180 ° C., indicating that the magnet of the present invention has an excellent heat resistant use temperature. This reason is presumed to be largely attributable to the fact that the recovered sintered magnet scrap used is a sintered magnet having a high heat resistance with a large amount of Dy, Tb, etc. as can be seen from the component analysis.

<Example 7-2>
After heat-treating the powder having an average particle size of 58 μm obtained from the municipal waste recovered in Example 7 together with the Ti getter material in a high vacuum under the conditions of (a) 400 ° C. × 48 hr, (b) 600 ° C. × 12 hr, After adding 4.5 wt% of an epoxy binder to the molded powder and kneading, a compound is obtained, and further mixed with an inorganic solvent and wet compression molded at 4.0 Ton / cm ² in a magnetic field, and further 10 at a pressure of 300 MPa. CIP for minutes. The CR of each of the obtained anisotropic bond magnetic properties was (a) 0.57 and (b) 0.55. Table 7-4 shows the magnetic characteristics of Example 7-2 (a) and (b).

<Example 8>
Measurement of the magnetic properties and ICP component analysis (n = 3) of the municipal waste recovered as the starting material gave the following properties and analysis values (Tables 8-1 and 8-2). The analytical values of the amount of O and C of the recovered waste were 6.5 wt% and 3.9 wt%, respectively. The average crystal grain size was 8.2 μm as measured by n = 5. This alloy powder was ball milled in acetone to obtain a press-molded powder. The average particle size is 84 μm. The obtained powder was heat treated in a high vacuum containing Ca getter material at 400 ° C. × 48 hr, and then 3.8 wt% of an epoxy binder was added to the molded powder and kneaded to obtain a compound, and 5.0 Ton in a magnetic field. After compression molding at / cm ² , CIP treatment is further performed at a pressure of 300 MPa for 10 minutes. The obtained anisotropic bond magnetic properties and the magnetic properties (n = 5) of the collected magnets are shown below together with the measured average magnetic properties. The obtained anisotropic bonded magnet had a CR of 0.43.

<Discussion>
From the above, the anisotropic rare earth bonded magnet according to the present invention and the anisotropic rare earth bonded magnet obtained by the production method according to the present invention have a specific component composition, an average particle diameter of 30 to 200 μm, and It has been found that it has an average crystal grain size of 1 to 15 μm and high magnet properties (maximum energy product) of 96 to 270 kJ / m ³ .

As described above, the anisotropic rare earth bonded magnet according to the present invention has excellent magnetic properties as compared with conventional magnets, and according to the manufacturing method of the present invention, such an excellent performance can be obtained even when recovered waste is used. It was found that a magnet was obtained.

According to JABM (Japan Bond Magnetic Materials Association), the market for rare earth bonded magnets is estimated to be about 10 billion in the domestic market and about 50 billion worldwide. The market growth rate is about 11% per year, and demand is expected to continue expanding.

Most of the rare earth bonded magnets on the market today are isotropic bonded magnets. There are currently no materials that can be used in large quantities for anisotropic bonded magnets due to marketability, magnet material performance, mass production cost, etc. Has a very low market share of several percent.

If the magnet material of the present invention becomes available, the conversion from isotropic to the anisotropic bonded magnet of the present invention will proceed rapidly. In other words, by switching from isotropic to anisotropic, electronic components can be reduced in size, weight, resources, energy, and efficiency.

Also, it can be applied to new applications and fields that could not be realized with conventional isotropic bonded magnets.

Claims

An anisotropic rare earth bonded magnet manufactured from a rare earth anisotropic sintered magnet,
As components other than iron (Fe), at least 13 to 35 wt% of neodymium (Nd), 0.3 to 1.3 wt% of boron (B), 0 to 30 wt% of samarium (Sm), and 0 of cobalt (Co) -15 wt%, nickel (Ni) 0-5.5 wt%, aluminum (Al) 0-5.5 wt%, and nickel (Ni) and aluminum (Al) combined, 0.3 wt% or more And the balance is iron (Fe), the maximum energy product (BH) max has a magnetic property of 96 to 270 kJ / m 3 , and the average particle size of the pulverized raw material is 30 to 200 μm (microns), and An anisotropic rare earth bonded magnet, characterized in that the main phase forming each particle has a structure having an average crystal grain size of 1 to 15 μm (microns).
A method for producing an anisotropic rare earth bonded magnet using a rare earth anisotropic sintered magnet as a raw material, wherein the rare earth anisotropic sintered magnet is mechanically pulverized in an inert atmosphere, and the pulverized material is subjected to high vacuum. Alternatively, the method comprises a step of strain relief annealing at a temperature of 400 to 600 ° C. in an inert atmosphere and a holding time of 12 hours or more, and a step of kneading the strain relief annealed material and a binder to form a magnetic field. A method for producing an anisotropic rare earth bonded magnet, which is characterized.
The method for producing an anisotropic rare earth bonded magnet according to claim 2, wherein the rare earth anisotropic sintered magnet is recovered scrap.
The anisotropic rare earth according to claim 3, wherein the rare earth anisotropic sintered magnet is neodymium sintered magnet recovered scrap or a mixture of neodymium sintered magnet recovered scrap and samarium cobalt sintered magnet recovered scrap. A method of manufacturing a bonded magnet.
When the rare earth anisotropic sintered magnet recovery scrap is a mixed scrap, before subjecting to the pulverization step, sampling the recovered scrap in advance, performing component analysis of the recovered magnet material, and confirming the composition of neodymium and neodymium and samarium The manufacturing method of the anisotropic rare earth bond magnet of Claim 3 containing this.
The method for producing an anisotropic rare earth bonded magnet according to claim 2, wherein the magnetic field molding includes a compression molding step, and a wet molding method is used in the compression molding step.
The method for producing an anisotropic rare earth bonded magnet according to claim 6, wherein in the compression molding step, two-stage press molding is performed in which a CIP step is added after the compression molding.