JPH09186011A - Anisotropic bond magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bond magnet which does not generate cracks in magnet powder at the time of molding, and is excellent in heat resistance, resistance to weather and magnetic characteristics. SOLUTION: R-Fe-B based alloy ingot or coarse crushed powder obtained by grinding the ingot is made anisotropic magnet powder having recrystallization grain aggregate structure of tetragonal system R2 Fe14 B phase having a specific average recrystallization grain diameter, by an H2 treatment method under a specified heat treatment condition. Before the compounding and mixing with binder resin, or at the same time of compounding and mixing, or after compounding and mixing, a specified amount of very fine liquid quench R-Fe-B based permanent magnet fine powder is compounded and mixed with the anisotropic magnetic powder. By molding and hardening, the liquid quench R-Fe-B based permanent magnet fine powder is predominantly buried in magnetic powder gap at the time of molding, the hole ratio in the bond magnet is reduced, permeation of O2 and H2 O in the magnet is restrained, cracks in the magnet powder is prevented at the time of molding, and very active metal fracture in the bond magnet is reduced, so that heat resistance and resistance to weather are improved, and at the same time, Br, (BH)max, and rectangularity are improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent heat resistance and weather resistance as well as magnetic properties, in particular, residual magnetic flux density (hereinafter referred to as Br), maximum magnetic energy product (hereinafter referred to as (BH) max) and squareness. Related to the anisotropic bond magnet,
An R-Fe-B alloy ingot or a coarsely crushed powder obtained by crushing the ingot is subjected to an H ₂ treatment method under a specific heat treatment condition to obtain a tetragonal R ₂ Fe having a specific average recrystallized grain size. ₁₄
An anisotropic magnet powder having a B-phase recrystallized grain texture was prepared, and a specific amount of a fine liquid quenched R-Fe-B magnet powder and a binder resin were mixed and mixed, and then obtained by molding. The present invention relates to an anisotropic bonded magnet having excellent heat resistance, weather resistance, Br, (BH) max, and squareness.

[0002]

2. Description of the Related Art In general, a bonded magnet is compared with a sintered magnet,
In spite of its inferior magnetic properties, its use has been rapidly expanding in recent years due to its excellent mechanical strength and its high degree of freedom in shape. Such a bonded magnet is formed by bonding with a magnet powder and an organic binder, a metal binder, or the like. The magnetic properties of the bonded magnet depend on the magnetic properties of the magnet powder used.

[0003] As magnet powder for bonded magnets, (1) R
-A magnet powder obtained by mechanical pulverization method or H ₂ occlusion collapse method or a (2) liquid quenching method or an atomizing method, which is obtained by ultra-quenching a molten alloy from an Fe-B-based ingot. Magnet powder is used.

In the former (1) magnet powder, R ₂ Fe ₁₄ B
The R ₂ Fe ₁₄ B phase becomes R
The structure does not become a structure surrounded by the rich phase, but becomes a structure in which the R-rich phase is partially adhered to a part of the R ₂ Fe ₁₄ B phase, and distortion remains in the magnet powder at the time of pulverization. When the magnetic force iHc is reduced to 3 kOe or less and the magnet powder subjected to the strain relief heat treatment or the aggregated powder that forms an R-rich phase at the R ₂ Fe ₁₄ B phase boundary is used as a bonded magnet powder, As the pressure is increased, the iHc of the bonded magnet is significantly reduced, and the magnetic properties are also reduced when the binder is cured.

[0005] On the other hand, in the case of the latter (2) magnet powder, since the crystal direction of each crystal grain of each R ₂ Fe ₁₄ B phase is arbitrary and the magnetic properties of the powder are isotropic, the bond magnet itself is also the same. Since it is anisotropic, high magnetic properties cannot be expected, and there is a problem that its use is practically limited.

Further, in order to obtain a low-priced and high-performance bonded magnet, ferrite magnet powder has high-performance R-Fe-B.
High-performance bonded magnets in which a system magnet powder is added and blended have been proposed, but the R—Fe—B system magnet powder is an isotropic magnet powder such as ultra-quenched powder or crushed ingot powder, Improvement Improvement was small (Japanese Patent Laid-Open No. 61-284906).
JP-A-63-287003, JP-A-2-7820
4, JP-A-3-181104, and JP-A-3-2223.
03).

[0007]

[SUMMARY OF THE INVENTION Therefore, recently, as a magnetic powder for an anisotropic bonded, with H ₂ treatment for a specific heat treatment conditions for R-Fe-B alloy ingot or coarse pulverized powder after pulverization, anisotropic R-Fe-B magnet powder without the recrystallization texture consisting of R ₂ Fe ₁₄ B tetragonal phase has been proposed (Japanese Patent Laid-Open No. 1-132106).

As a method of producing an anisotropic bonded magnet using the anisotropic magnet powder, a resin liquefied with a solvent as a binder is added to the magnet powder, and then the solvent is evaporated to form the powder. After drying, compression molding and a curing heat treatment for curing the binder are generally known.

However, the anisotropic magnet powder as a raw material powder is very easily oxidized, and even if the powder surface is coated in advance by a coupling process or the like, cracks occur in the magnet powder due to stress during molding. However, the active metal surface is exposed to be oxidized more easily, and the formed bonded magnet has a low density and a large number of pores, and O ₂ and H ₂ O easily enter the pores. There is a problem that the bonded magnet is oxidized and the magnetic properties deteriorate with time. Further, cracking of the magnet powder during molding means introducing a large amount of strain into the magnet powder,
It is not preferable from the viewpoint of deteriorating coercive force and squareness.

The present invention solves the above-mentioned problems of anisotropic bonded magnets, does not cause cracks in the magnet powder during molding, and has heat resistance and weather resistance as well as magnetic properties, especially Br, (B
It is intended to provide an anisotropic bonded magnet having excellent H) max and squareness.

[0011]

In order to solve the problems of conventional anisotropic bonded magnets, the inventors have conducted various studies on a method of reducing voids in a molded bonded magnet. , Before and / or at the same time as the compounding and mixing of the resin as a binder to the magnet powder, or after the compounding and mixing, by mixing and mixing a specific amount of a fine liquid quenching R-Fe-B based permanent magnet powder, Rapid cooling R-
The Fe-B magnet fine powder is preferentially filled in the magnet powder gap or the magnet powder gap thinly coated with resin at the time of molding, and such a phenomenon reduces the porosity in the bonded magnet. Liquid quenching R-F occupying magnet powder gap
It has been found that the e-B magnet powder alleviates stress concentration on the local part of the magnet powder that occurs during molding and suppresses cracking of the magnet powder.

The inventors have also found that 1) the reduction of voids prevents O ₂ and H ₂ O from penetrating into the interior of the magnet, and significantly improves heat resistance and weather resistance. Since the portion which was the void portion is replaced by the liquid-quenched R—Fe—B-based permanent magnet powder, the magnetic characteristics, especially Br,
(BH) max is improved, 3) Furthermore, by suppressing cracking of the magnet powder, the number of highly active metal fracture surfaces in the bonded magnet is reduced, so that heat resistance and weather resistance are further improved,
4) In addition, the introduction of strain is suppressed, so that the magnetic properties, particularly the squareness, are improved. 5) The action and effect are synergized, and the heat resistance and weather resistance of the bonded magnet are improved, and the magnetic properties are improved. The inventors have found that it is effective for improvement and completed the present invention.

That is, according to the present invention, an anisotropic R-Fe-B magnet powder having a recrystallized grain structure composed of an R ₂ Fe ₁₄ B tetragonal phase having an average recrystallized grain size of 0.05 μm to 50 μm. And 0.9 to 49 with respect to the total of the magnet powder.
1% to 10% by weight of liquid quenching R-Fe-B magnet fine powder
An anisotropic bonded magnet, characterized in that it is made of a resin of wt% and is filled with liquid quenching R—Fe—B based magnet powder, which is a void of a bonded magnet in the past.

[0014]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, R ₂ Fe ₁₄ B
A magnet powder having a recrystallization texture composed of a tetragonal phase is R-F.
The EB alloy ingot or the coarse particles obtained by coarsely pulverizing the ingot are homogenized or heated in an H ₂ gas atmosphere without homogenization, and the temperature is increased to 750 ° C. It is obtained by keeping in a H ₂ gas atmosphere at 950 ° C. for 30 minutes to 8 hours and subsequently in a vacuum atmosphere at 750 ° C. to 950 ° C. for 5 minutes to 4 hours, then cooling and pulverizing. Things.

The reason why the average particle size of the anisotropic R-Fe-B magnet powder is limited to 5 μm to 500 μm is 5 μm.
If it is less, it is easily oxidized and may burn during work,
If it exceeds 500 μm, it is not practical because it is not practical as a magnet powder.
m to 300 μm.

If the average recrystallized grain size of the anisotropic R-Fe-B magnet powder is less than 0.05 μm, it becomes difficult to magnetize, and if it exceeds 50 μm, the iHc (coercive force) becomes 5 kOe or less, and the magnetism is decreased. Since the characteristics deteriorate, 0.05 μm to 5 μm
0 μm, and the preferred average recrystallized particle size is 0.1 μm.
m to 10 μm.

In the present invention, a specific anisotropic R-Fe is used.
If the average particle size of the liquid-quenched R-Fe-B magnet powder mixed and mixed with the -B magnet powder is less than 1.0 μm, it is difficult in actual production and the magnetic properties of the powder are deteriorated.
If it exceeds m, the effect of reducing voids during molding, stress relaxation effect,
That is, the effect of suppressing cracking of the magnet powder is small, and the effect of improving heat resistance, weather resistance and magnetic properties is small, which is not preferable, and the particle size of the liquid-quenched R-Fe-B magnet powder is 1.0 μm.
m to 50 μm. The particle size of the preferable liquid quenched R-Fe-B magnet powder is 1.0 μm to 10 μm.

If the content of the liquid-quenched R-Fe-B magnet powder is less than 0.9 wt% with respect to the total amount of the magnet powder, the porosity-reducing effect, that is, heat resistance, weather resistance and magnetic properties are obtained. Is not obtained, and if it exceeds 49 wt%, the magnetic characteristics of the bonded magnet deteriorate, so 0.9 w
t% to 49 wt%. Preferred liquid quench R-Fe-
The compounding amount of the B-based magnet powder is 1 wt% to 30 wt%.

If the amount of the resin as the binder is less than 1 wt%, the strength of the bonded magnet cannot be sufficiently obtained, and if it exceeds 10 wt%, the magnetic properties are deteriorated, which is not preferable. The amount is 1 wt% to 1
It is set to 0 wt%. The resin may be a known thermosetting or thermoplastic resin, a solid resin may be used as a liquefied binder in a solvent, and the solvent may be heated and volatilized before molding the bonded magnet. The molding of the bond magnet may be performed by any known method such as injection molding or extrusion molding in addition to compression molding.

The rare earth element R used in the anisotropic R—Fe—B based magnet powder of the present invention accounts for 10 to 30 atomic% of the composition, and at least one of Nd, Pr, Dy, Ho, and Tb. Seeds, or even La, Ce, Sm, G
Those containing at least one of d, Er, Eu, Tm, Yb, Lu and Y are preferable. Further, although one of R is usually sufficient, in practice, a mixture of two or more kinds (Misch metal, cydim, etc.) can be used for reasons of availability. Note that R may not be a pure rare earth element, and may contain impurities that are unavoidable in production within the industrially available range.

R is an essential element in the above system magnet powder, and if it is less than 10 atomic%, the crystal structure becomes a cubic structure having the same structure as α-iron, so that high magnetic properties, especially high coercive force cannot be obtained. , More than 30 atomic%, the R-rich nonmagnetic phase increases, the residual magnetic flux density (Br) decreases, and a permanent magnet having excellent characteristics cannot be obtained. Therefore, R is desirably in the range of 10 at% to 30 at%.

B is an essential element in the above system magnet powder. If it is less than 2 atomic%, the rhombohedral structure becomes the main phase, and a high coercive force (iHc) cannot be obtained. Increase in non-magnetic phase, residual magnetic flux density (Br)
, The excellent permanent magnet cannot be obtained. Therefore, B is desirably in the range of 2 to 28 atomic%.

Fe is an essential element in the above-mentioned system magnet powder. If it is less than 65 atomic%, the residual magnetic flux density (Br) decreases, and if it exceeds 80 atomic%, a high coercive force cannot be obtained. % To 80 atomic%.
Also, substituting a part of Fe with Co can improve the temperature characteristics without impairing the magnetic characteristics of the obtained magnet, but when the Co substitution amount exceeds 20% of Fe,
On the contrary, the magnetic characteristics are deteriorated, which is not preferable. When the amount of substitution of Co is 5 at% to 15 at% in terms of the total amount of Fe and Co, (Br) is increased as compared with the case where no substitution is made, which is preferable for obtaining a high magnetic flux density.

In addition to R, B, and Fe, the presence of unavoidable impurities in industrial production can be tolerated. For example, a part of B may be 4.0 wt% or less of C, 2.0 wt% or less of P, .0
By replacing at least one of S by wt% or less and Cu by 2.0 wt% or less with a total amount of 2.0 wt% or less, it is possible to improve the productivity and reduce the cost of the permanent magnet.

Further, Al, Ti, V, Cr, Mn, B
i, Nb, Ta, Mo, W, Sb, Ge, Ga, Sn,
At least one of Zr, Ni, Si, Zn, and Hf is added to the magnet powder because it is effective for improving the coercive force and the squareness of the demagnetization curve or improving the productivity and reducing the price. be able to. In addition, the upper limit of the addition amount is such that the (BH) max of the bonded magnet is 14 MGOe or more.
Since (Br) requires at least 8 kG or more, a range satisfying the condition is desirable.

The liquid-quenched R-Fe-B magnet powder used for blending and mixing is obtained by finely pulverizing magnet powder referred to by trade name MQP (average particle size: about 150 μm) to several to several tens of μm. The composition of the liquid-quenched R-Fe-B magnet powder is R (where R is at least one of rare earth elements including Y) 8 atom% to 30 atom%, B2 atom% to 28 atom%, Fe42
It is preferable that the main phase is a tetragonal compound, which is composed of a compound structure having a magnetic anisotropy of 5 μm or less and having a crystallinity of 5 μm or less as the main component of the alloy melt in an amount of at% to 90 at%.

The liquid-quenched R-Fe-B magnet powder is magnetically obtained by recrystallizing a tape or ribbon having an amorphous structure or a mixed structure of amorphous and ultrafine crystal by ultra-quenching. An isotropic R-Fe-B based magnet powder that is isotropic can be used. Similarly, isotropic R—Fe—B magnet powder that is magnetically isotropic in an intermediate state between an amorphous material and a soft magnetic crystalline material by ultra-quenching can be used.

With respect to the composition of the liquid-quenched R-Fe-B magnet powder, when R is less than 8 atom%, high magnetic properties, particularly high coercive force cannot be obtained, and when R exceeds 30 atom%, the residual magnetic flux density (B
Since r) is lowered and a permanent magnet material having excellent characteristics cannot be obtained, the range is 8 atom% to 30 atom%, and if B is less than 2 atom%, a high coercive force (iHc) cannot be obtained. If it exceeds atomic%, the B-rich nonmagnetic phase increases and the residual magnetic flux density (Br) decreases, so 2 atomic% to 28 atomic%
When the content of Fe is less than 42 atomic%, the residual magnetic flux density (Br) decreases, and when it exceeds 90 atomic%, a high coercive force cannot be obtained. Therefore, the content of Fe is set to 42 atomic% to 90 atomic%.
A part of Fe can be replaced by Co, or various additive elements can be added.

In the present invention, in addition to the liquid quenching R-Fe-B magnet fine powder, ferrite magnet powder, R-Fe-B nanocomposite magnet fine powder, R-
The Co-based magnet fine powder and the R-Fe-N-based magnet fine powder may be mixed and mixed.

[0030]

【Example】

Example 1 As a raw material, melt casting was performed in a vacuum melting furnace to obtain an alloy ingot for an R-Fe-B magnet whose composition is shown in Table 1. These alloy ingots were homogenized at a temperature of 1120 ° C. for 10 hours in an Ar atmosphere. Insert the ingot into the heating furnace,
As H ₂ gas of 60 Torr, the temperature in the heating furnace was raised from room temperature to a temperature of 850 ° C., and subsequently kept at a temperature of 850 ° C. for 3 hours, then kept at 850 ° C. for 1 hour to perform H ₂ removal, and a vacuum was applied. The exhaust gas was cooled to 1 × 10 ⁻⁵ Torr. After that, the ingot was crushed in an Ar atmosphere to 300 μm or less to obtain an R—Fe—B based magnet powder. The obtained magnet powder was R ₂ Fe _{14 having} an average crystal grain size of 0.5 μm.
The anisotropic magnet powder had a recrystallized grain texture composed of a B tetragonal phase.

The liquid quenching R-Fe-B system permanent magnet fine powder has a composition of Nd12 at% -B5.4 at% -Co5a.
MQP with an average particle size of about 150 μm
-B magnetic powder (trade name, manufactured by General Motors, USA) was used. A liquid quenched Nd-Fe-B based magnet fine powder having an average particle size of 2.7 μm obtained by finely pulverizing the magnetic powder with a ball mill is used as the anisotropic magnet powder having an average particle size of 150 μm obtained in the above-mentioned step. After blending 10 wt% with respect to the total, mixing in a V-type mixer for 30 minutes, further blending and mixing 3 wt% epoxy resin as a binder, and then vacuum drying, 1
After molding at a molding pressure of 7 ton / cm ² in a magnetic field of 2 kOe,
The temperature was maintained at 170 ° C. for 1 hour to cure, and an anisotropic bonded magnet was obtained.

Table 2 shows the magnetic properties, squareness, porosity, and weather resistance test results of the obtained anisotropic bonded magnet. Here, the porosity is obtained by calculation from the density and the compounding ratio of the anisotropic R—Fe—B magnet powder, the liquid quenched R—Fe—B magnet powder and the resin, and the measured density of the molded bond magnet. It was

The test conditions for the heat resistance and weather resistance tests were 100 ° C. × 1000 hours in the atmosphere, and the change with time of the magnetic flux during the test was measured. The test method for the change of magnetic flux over time is to measure the magnetic flux after magnetizing the test piece, then leave it in the atmosphere at 100 ° C for 1000 hours, magnetize the test piece again, measure the magnetic flux, and remagnetize it. A demagnetization rate that does not restore even after the measurement, that is, a permanent demagnetization rate was calculated. This permanent demagnetization is caused by deterioration due to corrosion of the magnet or the like, and can be a judgment index for improving heat resistance and weather resistance.

Example 2 3 w as a binder was added to the magnet powder obtained in Example 1.
After mixing and mixing t% epoxy resin and vacuum drying, and then mixing and mixing the liquid-quenched Nd-Fe-B magnet fine powder described in Example 1 with 10 wt% based on the total of the magnet powder. An anisotropic bonded magnet was prepared under the same manufacturing conditions as in Example 1, and the magnetic properties, porosity, and weather resistance test results of the obtained anisotropic bonded magnet are shown in Table 2.

Example 3 Composition No. obtained in Example 1 2 to the magnet powder of No. 2, the liquid-quenched Nd-Fe-B based magnet fine powder described in Example 1,
Anisotropic bond magnet was prepared under the same manufacturing conditions as in Example 1 except that the compounding amount was changed in the range of 0 to 50 wt% with respect to the total of the magnet powder, and the anisotropy obtained was obtained. The magnetic properties of the bonded magnet are shown in FIG. 1, and the porosity and weather resistance test results are shown in FIG.

Example 4 Composition No. obtained in Example 1 1.2μm, 2.7μ made by changing the ball mill grinding time to the magnet powder of No. 2
m, 3.5 μm, 4.9 μm, 6.5 μm, 9.7 μm
Anisotropic bond under the same manufacturing conditions as in Example 1 except that 10 wt% of the liquid-quenched Nd-Fe-B-based magnet fine powder of each average particle diameter is mixed and mixed with the total of the magnet powder. A magnetic property of the obtained anisotropic bonded magnet is shown in FIG. 3, and porosity and weather resistance test results are shown in FIG.

Comparative Example 1 Liquid quenching R-Fe-B was added to the magnet powder obtained in Example 1.
An anisotropic bonded magnet was prepared under the same manufacturing conditions as in Example 1 except that the permanent magnet powder was not mixed and mixed, and the magnetic properties, squareness, porosity and weather resistance of the obtained anisotropic bonded magnet were obtained. The sex test results are shown in Table 2.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

The anisotropic bonded magnet according to the present invention has an R
A —Fe—B-based alloy ingot or a coarsely pulverized powder obtained by crushing the ingot is subjected to an H ₂ treatment method under specific heat treatment conditions to obtain a tetragonal R ₂ Fe having a specific average recrystallized grain size. ₁₄
Anisotropic magnet powder having a B-phase recrystallized grain texture, obtained by compounding and mixing a predetermined amount of a fine liquid quenching R-Fe-B system permanent magnet powder and a binder resin, and molding the mixture. As is clear from the examples, it has excellent heat resistance, weather resistance and magnetic properties.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount (wt%) of mixed liquid quenching Nd—Fe—B based permanent magnet powder (average particle size 2.7 μm) and the magnetic properties of the obtained bonded magnet.

FIG. 2 shows the amount (wt%) of mixed liquid-quenched Nd—Fe—B based permanent magnet powder (average particle size 2.7 μm), the porosity (%) of the obtained bonded magnet, and the permanent property after a weather resistance test. It is a graph which shows the relationship with a demagnetization rate (%).

FIG. 3 is a graph showing the relationship between the average particle size (μm) of liquid rapidly cooled Nd—Fe—B based permanent magnet powder mixed with 10 wt% and the magnetic properties of the obtained bonded magnet.

FIG. 4 is an average particle diameter (μm) of a liquid-quenched Nd—Fe—B system permanent magnet powder mixed with 10 wt%, a porosity (%) of the obtained bonded magnet, and a permanent demagnetization rate (%) after a weather resistance test. ) Is a graph showing the relationship with.

Claims (1)

[Claims] An average recrystallized grain size of 0.05 μm to 50 μm.
liquid of 0.9 to 49 wt% with respect to the total of the anisotropic R-Fe-B magnet powder having the recrystallized grain texture of the R ₂ Fe ₁₄ B tetragonal phase of m and the magnet powder. Rapid cooling R-
An anisotropic bonded magnet comprising Fe-B based magnet powder and 1 to 10 wt% of resin.