JPH0775204B2 - Method for manufacturing polymer composite rare earth magnet - Google Patents

Description

[Field of Industrial Application] The present invention relates to a method for producing a polymer composite magnet typified by a so-called rubber magnet, and in particular, a rare earth metal typified by a Nd / Fe / B system permanent magnet. The present invention relates to improvement of a polymer composite type rare earth magnet using an R ₂ T ₁₄ B rare earth magnet powder containing (R), a transition metal (T) and boron (B) as main components.

[Conventional technology]

The polymer composite type magnet is one in which magnet powder is dispersed in polymer resin, or magnet powder is bound with polymer resin. This magnet has various advantages not found in cast magnets, sintered magnets, and the like, such as elasticity and workability, and is used in various fields. However,
Since it is made of a magnetic powder and a non-magnetic resin, it has a drawback that it has lower magnetic characteristics than a sintered magnet or the like.

Therefore, it is attempted to achieve high magnet characteristics by anisotropy such as orienting the powder in a magnetic field. As the magnetic powder to be dispersed and bound, various kinds have been used so far, but in the present invention, R ₂ T typified by the Nd / Fe / B system showing the highest magnetic properties at present. ₁₄ B-based magnet powder is used.

Polymer composite magnets using conventional rare earth magnet powder are manufactured by heat treating alloy ingots obtained by melting raw materials, crushing, mixing the powder with polymer resin, and molding in a magnetic field. It was It was hoped that the magnet alloy powder used here would consist of fine single crystal particles in order to improve the crystal orientation in a magnetic field.

[Problems to be Solved by the Invention]

However, in R ₂ T ₁₄ B-based alloys represented by Nd / Fe / B-based magnets, the coercive force ( _I H _C ) decreases due to mechanical stress during pulverization, so that the powder is formed from single crystal particles. In the fine region, the _I H _C was significantly reduced. Therefore, in the manufacturing method using the molten ingot as a starting material, even if the sintered magnet having a high _I H _C is crushed and used as the magnet powder, the polymer composite type magnet has remarkably low magnet characteristics. .

Furthermore, in the manufacturing method in which the ingot is heat-treated and then pulverized into a polymer composite magnet, only extremely poor magnet characteristics having no existence value are exhibited.

On the other hand, R · T · decrease of _I H _C by crushing does not occur almost
As a method for producing a B-based magnet alloy, a liquid quenching method has been known in which a molten alloy is jetted onto a rotating roll or the like and is rapidly quenched to obtain a magnet alloy.

However, anisotropy could not be realized with the powder obtained by this production method. After that, it was found that hot-plastic working of this liquid-quenched alloy yielded magnet powder capable of anisotropy. Since this method requires high pressure at high temperature, the equipment is expensive and large-scaled, and there is still concern about stabilizing the characteristics in the production state, and powders with small characteristic variations in mass production. Is still difficult to obtain and is not industrially useful.

The technical problem of the present invention is to provide a method for manufacturing a high-performance anisotropic polymer composite magnet by utilizing the manufacturing process of an R / T / B system sintered magnet that is usually carried out. Therefore, it is a very useful manufacturing method industrially.

[Means for Solving the Problems]

According to the present invention, R ₂ T ₁₄ containing Nd, Fe, B as a main component is used.
In a method for producing a polymer composite magnet using B (where R is Y and a rare earth element, T is a transition metal) alloy powder using a polymer resin, the R ₂ T ₁₄ B alloy powder is R ₂ A sinter was produced from the pulverized powder obtained by pulverizing a T ₁₄ B-based alloy ingot by powder metallurgy, and the pulverized powder of the sinter was finely pulverized. , R ₂ T ₁₄ B
A method for producing a polymer-composite rare earth magnet, characterized by comprising a system alloy ingot replaced with a quenched alloy powder produced by a liquid quenching method.

Here, in the present invention, the method for producing a polymer composite type magnet using a polymer resin means a method of mixing a raw material alloy powder with a polymer resin and performing injection molding, extrusion molding or compression molding, or A method of impregnating a polymer resin after compression molding.

That is, the present invention is to pulverize an alloy ingot obtained by melting and then sinter the powder compact obtained by compacting in a magnetic field to obtain a sintered compact having a high degree of crystal orientation, and then sintering this sintered compact. After crushing the aggregate, by using the powder adjusted to contain the R ₂ T ₁₄ B-based alloy powder produced by the liquid quenching method in the particle size range of 30 μm or less in the crushed powder of the sintered body, a high magnet can be obtained. It is intended to realize an R / T / B-based polymer composite magnet having characteristics.

Orientation of the magnetic properties of the present invention, _I H _C of the sintered body ground powder by heat treatment is related to the improvement of the squareness of the Br and demagnetization curve, this effect molding powder has a plurality of alignment It is deeply attributed to the fact that it is composed of crystal grains. However, the improvement in magnetic properties of the powder by heat treatment tends to decrease as the powder particle size decreases.

As a result of various experiments conducted by the present inventors, particles of 30 μm or less in the crushed powder of the sintered body are obviously difficult to recover from damage due to crushing even by heat treatment. In the range of 30 μm or less, the liquid quenching method is used. By containing the liquid-quenched alloy powder produced by the above method or the alloy powder obtained by hot plastic working of the liquid-quenched alloy, it is possible to obtain an R / T / B-based polymer composite magnet having high magnet characteristics. discovered.

INDUSTRIAL APPLICABILITY The present invention is industrially very useful because most of powders for polymer magnets can be manufactured by using a manufacturing process of a sintered magnet which has high characteristics and can be processed in a large amount, and shows a magnet characteristic with less variation. Becomes

It was stipulated that the R ₂ T ₁₄ B-based alloy powder produced by the liquid quenching method should be contained in the 30 μm particle range in the crushed powder of the sintered compact because the effect of inclusion was saturated in the range of 30 μm or more. This is because the effect becomes remarkable when the thickness is 30 μm or less.

The present invention provides a powder that can be applied to a wide variety of methods for producing polymer composite type magnets such as impregnation type, compression molding type and injection molding type. Moreover, since a high-performance polymer composite magnet can be simply realized, it is industrially very useful.

Examples will be described below.

〔Example〕

Example 1. Nd with a purity of 97 wt% (the balance is other rare earth elements mainly composed of Ce and Pr), Dy with a purity of 99 wt% or more, ferroboron (B pure content approximately
20wt%) and electrolytic iron are used, (Nd _0.9・ Dy _0.1 ) is 34.0
An ingot having a composition of wt%, B of 1.0 wt% and the balance of Fe was melted by high frequency heating in an argon atmosphere to obtain an alloy ingot.

Next, this ingot was roughly crushed and then finely crushed to an average particle size of about 2 μm using a ball mill. This alloy powder was molded into a rectangular parallelepiped at a pressure of 1 ton / cm ^{2 in} a magnetic field of about 20 kOe. Next, this molded body was held in vacuum at 1000 ° C. for 1 hour and then in Ar for 3 hours to obtain a sintered body. This sintered body
It had a density of 7.55 gr / cm ³ and an average crystal grain size of about 5 μm. A part of this was aged at 600 ℃ for 2 hours and the magnet characteristics were measured. As a result, Br12.8kG, _I H _C 20kOe, (BH) max.39M.G.Oe
It was about.

The sintered body not subjected to the aging treatment was roughly pulverized to have a particle size of 300 μm or less, and then the powder was heat-treated at 600 ° C. for 1 hour in vacuum and 4 hours in Ar.

On the other hand, after remelting the alloy ingot by high frequency heating in Ar atmosphere, it is sprayed on a Cu roll with a peripheral speed of about 40 m / sec to obtain a liquid-quenched alloy ribbon and flakes with a thickness of about 20 μm and a width of about 3 mm. It was Next, after roughly crushing this liquid quenched ribbon, Ar
Hot pressing was performed in an atmosphere at 700 ° C. and a pressure of 1 ton / cm ² to obtain a molded body. This density was about 7.50 gr / cm ³ . next,
The compact was uniaxially pressurized at 700 ° C. and a pressure of 2.5 ton / cm ^{2 in} an Ar atmosphere, and hot plastic working was performed so that the dimension in the pressing direction was about 1/5. This processed compact has magnetic anisotropy in the pressing direction, a crystal grain size of about 0.3 μm and a thickness of about 0.3 μm.
Plate-like crystals of 0.1 μm were laminated. The magnet characteristics of this compact are Br12.2kG, _I H _C 22kOe, (BH) max.33M.G.Oe
It was about. Next, this molded body was finely pulverized to an average particle size of about 10 μm.

Next, the fine particles in the crushed powder of the sintered body that was previously heat-treated
It was separated and removed in the range of μm or less, 30 μm or less, 40 μm or less, 50 μm or less, and the corresponding amount was supplemented with the hot plastic work compact powder, respectively, and it was about 5 wt.
%, 30μm or less about 10wt%, 40μm or less about 20wt%, 5
Below 0 μm, it was about 30 wt%.

Next, after mixing polyethylene with 35% by volume of this powder,
A polymer composite magnet was obtained by injection molding into a mold while applying a magnetic field of 20 kOe at about 100 ° C. Its magnet characteristics are about 30kO
The result of measurement by applying a magnetic field of e is shown in FIG. 30μ
The magnetic properties of the polymer composite magnet are remarkably improved by substituting the crushed powder of the sintered body of m or less with the hot plastic working powder.

For reference, the aging-treated sintered body mentioned above is also 30
Coarse pulverization to 0 μm or less, polyethylene mixing and injection molding in the same manner to produce a polymer composite magnet
Br5.4kG, _I H _C 3.5kOe, was (BH) max.4.5MGOe.

Example 2 Same as Example 1 using cerium disim composed of 5 wt% Ce, 15 wt% Pr, and balance Nd (however, other rare earth elements were included as Nd), ferroboron, electrolytic cobalt, and aluminum. And the rare earth element R is 32 wt% and Co is 7 wt%
%, Al was 1 wt%, and the balance was Fe.

Next, using this ingot, in the same manner as in Example 1, crushing, forming in a magnetic field, and sintering at 1040 ° C. were performed. The sintered body obtained here had a density of about 7.55 gr / cm ³ and was composed of crystals having an average particle size of about 6.5 μm. When a part of this sintered body was aged at 600 ℃ for 2 hours, Br12.2kG, _I H _C 11.5kO
It was e, (BH) max33.5M.G.Oe.

After roughly pulverizing the sintered body that has not been subjected to aging treatment to a particle size of 500 μm or less, fine particles of 20 μm or less, 3
It was separated and removed in the range of 0 μm or less and 40 μm or less. The separated amount is about 3 wt%, about 7 wt%, and about 15 wt% of the total amount of powder, respectively.
It was wt%.

On the other hand, using an alloy ingot, in the same manner as in Example 1, the alloy was injected onto a Cu roll having a peripheral speed of about 15 m / sec to give a thickness of about 5
A liquid-quenched thin slice with a width of 0 μm and a width of about 7 mm was obtained. This thin piece was molded in a magnetic field to obtain a powdery liquid quenched thin piece. The flakes and was molded in a non-magnetic field was measured the magnetic properties of the powder only 4πIs about 10 kG, Br about 7.5 kg, _I H _C about 18kOe, (BH) max. About 10M.
It was G.Oe. Next, this liquid quenched thin piece was finely pulverized with a ball mill to an average particle size of about 5 μm.

Next, the crushed powder of the sintered body from which the fine particles had been removed was supplemented with an amount of the liquid rapidly crushed pulverized powder corresponding to the removal amount, and mixed. This mixed powder was placed in a magnetic field of about 20 kOe at 3 ton /
After being formed into a disk shape at a pressure of cm ² , it was held at 1000 ° C. in vacuum for 1 hour and in Ar for 1 hour and then rapidly cooled. The density of this heat-treated sample was about 6.3 gr / cm ³ .

Next, this heat-treated sample was evacuated, impregnated with an epoxy resin, and then held at 100 ° C. for 2 hours to be cured to obtain a polymer composite magnet. The measurement results of the magnet characteristics are shown in FIG.
The magnetic properties of the polymer composite magnet are remarkably improved by replacing the sintered powder having a particle size of 30 μm or less with the liquid quenching powder.

For reference, the aging-treated powder described above is also
After roughly crushing to 300 μm or less, similarly molding in a magnetic field, epoxy resin impregnation and curing, the magnet characteristics as a polymer composite magnet were measured and found to be d5.4gr / cm ³ , Br5.2kG, _I H _C 3.0k
It was Oe, (BH) max.3.5MGOe.

Example 3 Nd having a purity of 97 wt% (the rest are other rare earth elements mainly composed of Ce and Pr), ferroboron and electrolytic iron were used, and in the same manner as in Example 1, the rare earth element (R) was 33.5 wt%. , B is 1,1wt
%, The balance Fe was obtained.

Next, using this ingot, in the same manner as in Example 1, crushing, forming in a magnetic field, and sintering at 1020 ° C. were performed. The sintered body obtained here had a density of about 7.55 gr / cm ³ and was composed of crystals having an average grain size of about 6 μm. A part of this sintered body
Was 2 hours aging at _{600 ℃, Br13.7kG, I H C} 11.5kOe,
It was (BH) max.44M.G.Oe.

The sintered body not subjected to the aging treatment was roughly pulverized to have a particle size of 300 μm or less, and then the powder was heat-treated at 600 ° C. for 1 hour in vacuum and 4 hours in Ar.

Next, the fine particles in the crushed powder of the heat-treated sintered body were set to 20 μm.
Then, the mixture was separated and removed in the range of 30 μm or less and 40 μm or less, and the corresponding amount was filled with the liquid quenched fine powder (pulverized particle size of about 5 μm) prepared in Example 2 and mixed. The amount of compensation was about 5 wt%, about 10 wt%, and about 20 wt%, respectively.

Next, 25 vol.% Of the epoxy resin was mixed with this mixed powder, and the mixture was molded into a disk shape at a molding pressure of 5 ton / cm ^{2 in} a magnetic field of about 20 kOe. This molded body was kept at 100 ° C. for 2 hours to be hardened to obtain a polymer composite magnet. The measurement results of the magnet characteristics are shown in FIG. The magnetic properties of the polymer composite magnet are clearly improved by substituting the pulverized powder of the sintered compact of 30 μm or less with the liquid quenching powder.

For reference, the aging-treated powder described above is also
Was coarsely pulverized to 300μm or less, similarly heat treatment, the epoxy resin mixture, the magnetic field during molding, subjected to resin curing was measured for magnetic _{properties, Br5.5kG, I H C 3.0kOe,} (BH) max.4.0M. .G.
It was Oe.

As shown in the above examples, R ₂ T ₁₄ B having anisotropy
30 μm in powder for molding made by crushing sinter-bonded gold
By including the R ₂ T ₁₄ B-based alloy powder produced by the liquid quenching method in the following particle range, a polymer composite type magnet having significantly improved magnet characteristics can be realized.

In the above examples, Nd-Dy-Fe-B system, Ce-Pr-Nd-Fe
Only the --Co--Al--B system and the Nd--Fe--B system have been described.
Part of d is replaced with Y and other rare earth elements such as Gd, Tb, Ho, etc., Part of Fe is replaced with other transition metal such as Mn, Cr, Ni, etc. Part of B is replaced with other Even if it is replaced by a semi-metal such as Si, C, etc., the composition of the magnet alloy has Nd, Fe, B as a part of the main component, and it is a compound system of the magnet represented by Nd ₂ Fe ₁₄ B system. If R ₂ T ₁₄ B contributes to magnetism, the effect of the present invention can be easily expected.

Although only the Epokin resin and polyethylene are used as the polymer resin in this embodiment, any substance (for example, another polymer resin) that intervenes inside the molded body and contributes to the improvement of the strength of the molded body can be used. Those skilled in the art can easily understand that not only rubber and the like but also metal and the like are within the scope of the present invention.

Further, regarding the polymer composite magnetizing method shown in the examples, an impregnating mold for impregnating a molded body with resin, a compression molding mold for mixing powder and resin and then compression molding, and an injection after kneading powder and resin Although only the injection mold for molding is described, those skilled in the art can easily imagine that other molding methods such as extrusion molding and roll molding can be applied.

〔The invention's effect〕

As described above, according to the present invention, a method for manufacturing a high-performance anisotropic polymer composite rare earth magnet is utilized by utilizing the manufacturing process of an R / T / B system sintered magnet that is usually performed. Can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a powder particle diameter in a pulverized powder of a sintered compact substituted with a fine powder of a hot plastic working compact in Example 1 and a magnetic property of a polymer composite magnet, and FIG. FIG. 3 is a diagram showing the relationship between the powder particle size in the crushed powder of the sintered body replaced with the liquid quenching alloy powder in Example 2 and the magnetic properties of the polymer composite magnet. FIG. 3 is the liquid quenching alloy powder in Example 3. It is a figure which shows the relationship between the powder particle size in the substituted sintered compact pulverized powder, and the magnet characteristic of a polymer composite magnet.

Claims (1)

[Claims] 1. R ₂ T ₁₄ B containing Nd, Fe and B as main components (however,
R is at least one of Y and rare earth elements containing Nd as an essential component, and T is at least one of transition metals containing Fe as an essential component.) In a method for producing a polymer composite magnet, , The R ₂ T ₁₄ B-based alloy powder is R
₂ T ₁₄ B-based alloy Ingot crushed powder was used to make a sintered body by powder metallurgy, and this sintered body was finely pulverized. A method for producing a polymer composite type rare earth magnet, comprising: a R ₂ T ₁₄ B-based alloy ingot replaced with a quenched alloy powder produced by a liquid quenching method.