JPH0613212A - Rare earth magnetic particle, manufacturing method thereof and rare earth bond magnet - Google Patents

Abstract

PURPOSE:To obtain the low cost rare earth bond magnet having magnetic characteristics similar to those of conventional one by specifying the crystalline particle diameter for the level not exceeding specific value as well as Sm for specific quantity of R. CONSTITUTION:A ribbonlike alloy is produced using a single roll so that Sm may be composed of 20-80wt% of R (one or more than one kind of rare earth elements including Y). This alloy is crushed to be nitrified later. Later, the crushed alloy is further finely crushed to produce the particles in mean particle diameter not exceeding 20mum. Next, the produced particles are blended and kneaded with an epoxy base resin to be compression-molded into the bond magnet. Through these procedures, this rare earth bond magnet having excellent magnetic characteristics can be easily manufactured at low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth magnetic powder composed of a rare earth metal and a transition metal group and a rare earth bonded magnet.

[0002]

_2. Description of the Related Art Conventionally, R ₂ Fe ₁₇ N _x rare earth bonded magnets have been disclosed in JP-A-2-57663 and JP-A-2-257603 and J. Ma
gn. Magn. Mater. , 87 (1990) L2
In 51 and other papers, Sm ₂ Fe ₁₇ N _x system is reported.

[0003]

However, the Sm ₂ Fe ₁₇ N _x system in the prior art has the following problems.

(1) Among the rare earth elements, about 25% by weight of expensive Sm is contained, so that the price of the magnetic powder also increases.

(2) When Sm of Sm ₂ Fe ₁₇ N _x is replaced with another inexpensive rare earth metal, the magnetic properties are significantly deteriorated, and it is difficult to reduce the cost.

Therefore, the present invention solves such a problem, and an object of the present invention is to provide a rare earth magnetic powder and a rare earth bonded magnet which have the same magnetic characteristics as conventional ones and are low in cost. It is in.

[0007]

The rare earth magnetic powder of the present invention is a so-called R ₂ Fe ₁₇ N _x type magnetic material whose basic composition is mainly R, Fe and N, and 20 to 8 in which Sm is R.
It is characterized by being 0% by weight and having a crystal grain size of 20 μm or less. It is characterized in that a part of Fe is replaced with another transition metal group such as Co, Nb, or Ti. The rare earth magnetic powder is magnetically almost isotropic.

The method for producing the rare earth magnetic powder of the present invention comprises a melt span method, a mechanical alloying method, a hydrogen treatment method,
It is characterized by using a gas atomizing method.

The rare earth bonded magnet of the present invention is characterized by using the above rare earth magnetic powder. The rare earth magnetic powder is used by being mixed with another magnetic powder.
The other magnetic powder is R ₂ TM ₁₇ type magnetic powder or R ₂ Fe.
It is characterized by being a ₁₄ B type magnetic powder.

[0010]

According to the above constitution of the present invention, Sm ₂ Fe ₁₇ N _x
By substituting a part of Sm of the system with another rare earth metal and refining the structure, the following effects are obtained.

(1) In the present composition system, although the magnetic properties are deteriorated such that the coercive force is largely decreased due to the decrease of the anisotropic magnetic field, this system is a single domain particle type, so that the texture is fine. By adopting this, magnetic properties sufficient for practical use can be secured.

(2) Conventional magnetic powder such as Sm ₂ TM
_{The 17-} type and Nd ₂ Fe ₁₄ B-type powders are remarkably deteriorated in magnetic properties, particularly coercive force and squareness, by making them finer,
Since this composition system is a single domain particle type, and the characteristics are not deteriorated even with fine powders, it is possible to improve the magnetic characteristics by, for example, improving the density after molding by using them by mixing them.

The reasons for limiting the scope of the claims are as follows.

In claim 1, when the Sm in R is less than 20% by weight, the effect of cost reduction is small and the difference from the conventional one is small. If it exceeds 80% by weight, the anisotropic magnetic field becomes extremely small or the uniaxial anisotropy is lost,
The above range is desirable.

Similarly, the crystal grain size of claim 1 is 2
If it exceeds 0 μm, the effect of miniaturization is lost, so the above range is desirable, and the finer limit is not practical.

The effect of the other transition metal substituting a part of Fe in claim 2 is that Co has an improvement in thermal stability and an improvement in corrosion resistance due to an increase in the Curie temperature, and Nb.
Suppresses primary crystal Fe, but Ti, V, Cr, Mn, Z
Also in r, Mo, Hf, Ta, W, etc., the magnetic characteristics are improved by the effect of making the structure finer.

The term "nearly" isotropic in terms of magnetic properties in claim 3 means that slight anisotropy may occur especially when the structure is large or when it is pulverized. It is not limited to isotropic.

The melt-span method, the mechanical alloying method, the hydrogen treatment method and the gas atomizing method mentioned as the manufacturing method in claim 4 are examples of a method for obtaining a fine structure, and the present invention is not limited thereto. Absent.

With respect to another magnetic powder according to claim 6,
The Sm ₂ TM ₁₇ system and Nd ₂ Fe ₁₄ B according to claims 7 and 8.
However, the present invention is not limited to this.

[0020]

EXAMPLES The present invention will be described in detail below based on examples.

(Embodiment 1) Sm = 12.3, Ce = 12.
2, Fe = 75.5% by weight so that the composition is 2
A ribbon-shaped alloy was prepared at 4 m / sec using a single roll made of copper of 00 mm. The average crystal grain size was 19 μm. This alloy was homogenized in an argon gas atmosphere at 1100 ° C. for 6 hours, then pulverized to <125 μm, in a hydrogen + ammonia mixed gas at 450 ° C. for 1 hour, and in argon gas at 450 ° C. for 2 hours. Was subjected to a nitriding treatment. Then, it was finely pulverized with a ball mill to obtain a powder having an average particle size of 17 μm. The obtained powder is mixed and kneaded with 3% by weight of an epoxy resin and compression-molded at a molding pressure of 70 kg / mm ² to obtain 150
The bonded magnet was cured at 1 ° C. for 1 hour. This is referred to as Invention 1.

The magnetic characteristics of Invention 1 are as follows.

Br = 7.2 kG, iHc = 9.8 kOe,
(BH) max = 10.3 MGOe (Example 2) Sm = 20.1, Pr = 5.1, Fe = 7
An alloy was prepared in the same manner as in Example 1 so that the composition was 4.1, Nb = 0.7% by weight. However, the peripheral speed of the roll was 25 m / sec, and the average crystal grain size was 4 μm. This is referred to as Invention 2.

The magnetic characteristics of Invention 2 are as follows.

Br = 7.6 kG, iHc = 14.1 kO
e, (BH) max = 11.1MGOe (Example 3) Sm = 21.4, Pr = 6.2, Fe = 6
1.8, Co = 10.6% by weight so that the composition is <2
97 μm Sm, Nd powder and <177 μm Fe, Co
The powder was subjected to so-called mechanical alloying using a planetary mill. This powder in an argon gas atmosphere 7
Heat treatment was performed at 00 ° C. for 3 hours and at 450 ° C. for 4 hours in a nitrogen gas atmosphere. The average crystal grain size was 13 μm. This is referred to as Present Invention 3.

The magnetic characteristics of Invention 3 are as follows.

Br = 7.2 kG, iHc = 16.3 kO
e, (BH) max = 9.9MGOe (Example 4) Sm = 5.6, Y = 22.1, Fe = 69.
An alloy was prepared by melting and casting in an argon gas atmosphere using a high frequency melting furnace so that the composition was 6, Zr = 2.7% by weight. This alloy was heated to 850 ° C. in hydrogen at a rate of 5 ° C./minute, held for 30 minutes, and then further vacuumed for 30
Hold for minutes and allow to cool. The average grain size of the obtained alloy was 0.2 μm. This is referred to as Present Invention 4.

The magnetic characteristics of Invention 4 are as follows.

Br = 7.1 kG, iHc = 11.1 kO
e, (BH) max = 9.7MGOe (Example 5) Sm = 12.8, Ce = 2.6, Pr = 2.
6, Nd = 7.6, Fe = 73.1, Ti = 1.3% by weight
A spherical alloy was prepared by using the argon gas atomization method so that the above composition was obtained. The average grain size of the obtained alloy was 9.5 μm. This is referred to as Present Invention 5.

The magnetic characteristics of Invention 5 are as follows.

Br = 6.9 kG, iHc = 10.1 kO
e, (BH) max = 9.5 MGOe (Example 6) Sm = 24.2, Co = 45.7, Fe = 2
An ingot was prepared by melting and casting in an argon gas atmosphere using a high frequency melting furnace so that the composition was 2.9, Cu = 5.3, and Zr = 1.9% by weight. This ingot was subjected to solution treatment at 1150 ° C. for 24 hours in an argon gas atmosphere, held at 800 ° C. for 8 hours, and then at 4 ° C. at 0.5 ° C./minute.
An aging treatment of continuously cooling to 00 ° C. was performed. afterwards,
Coarse pulverization with a stamp mill and fine pulverization with a ball mill gave powder with an average particle size of 32 μm. This is designated as Powder 1.

Powder 1 and the present invention 1 having an average particle size of 3.2 μm were mixed at a ratio of 1: 9, mixed and kneaded with 2.8% by weight of epoxy resin, and 50 k in a magnetic field of 17 kOe.
It was pressure molded at g / mm ² . This is referred to as Present Invention 6.

Further, Comparative Example 1 is one in which a bonded magnet is made of only powder 1.

The magnetic characteristics of Invention 6 and Comparative Example 1 are as follows.

[0035] (Example 7) Nd = 12.4, Fe = 65.9, Co = 1
It was melted and cast in an argon gas atmosphere using a high-frequency melting furnace so as to have a composition of 5.9, B = 5.8% by weight, a quenched ribbon was prepared with a single roll, and crushed and heat-treated. This was designated as Powder 2.

Powder 2 and the present invention 2 having an average particle size of 4.4 μm were mixed in a ratio of 4: 6, mixed and kneaded with 3.0% by weight of an epoxy resin, and pressed at 50 kg / mm ^2. Molded. This is referred to as Invention 7.

Further, Comparative Example 2 is one in which only powder 2 is used as a bonded magnet.

The magnetic characteristics of Invention 7 and Comparative Example 2 are as follows.

[0039] As can be seen from the above examples, the present invention has obtained sufficiently high magnetic characteristics even when compared with, for example, Comparative Example 2, and the effect of mixing with other magnetic powders is clear, and the present invention is effective. It turns out that

[0040]

As described above, according to the present invention, Sm
Substituting a part of Sm of ₂ Fe ₁₇ N _x system with another rare earth metal,
By making the structure finer, it is possible to easily produce a rare earth bonded magnet with high magnetic properties at low cost, so it is possible to realize higher performance and miniaturization of applied motors and devices. It also has a great effect on the application side.

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Claims (8)

[Claims] 1. A basic composition is mainly a rare earth metal (one or more kinds of rare earth elements including Y: hereinafter abbreviated as R),
A so-called R ₂ Fe ₁₇ N _x magnetic material composed of Fe and N, wherein Sm is 20 to 80% by weight of R and the crystal grain size is 20 μm or less. 2. A part of the Fe is replaced with another group of transition metals such as Co, Nb and Ti.
The rare earth magnetic powder described. 3. The rare earth magnetic powder according to claim 1 or 2, wherein the rare earth magnetic powder is magnetically isotropic. 4. A so-called R ₂ Fe ₁₇ N _x system having a basic composition mainly composed of R, Fe and N, and having Sm of 20 to 80% of R, a melt-span method, a mechanical alloying method, a hydrogen treatment method, and gas atomization. A method for producing a rare earth magnetic powder, characterized by using a method. 5. A rare earth bonded magnet comprising the rare earth magnetic powder. 6. A rare earth bonded magnet, characterized in that the rare earth magnetic powder is used by being mixed with another magnetic powder. 7. The so-called R, wherein the other magnetic powder is composed of R and Co and optionally contains Fe, Cu, Zr and the like.
The rare earth bonded magnet according to claim 6, which is a ₂ TM ₁₇ series (TM: transition metal group) magnetic powder. 8. The rare earth bonded magnet according to claim 6, wherein the other magnetic powder is a so-called R ₂ Fe ₁₄ B based magnetic powder containing R, Fe and B.