JP2011023605A - Magnetic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic material which can be simply manufactured and has superior magnetic characteristics. <P>SOLUTION: Mixing magnetic powder and metallic glass, and heating them up to not lower than the deformation start temperature of the metallic glass manufactures the magnetic material. According to the magnetic material, by simple manufacturing of the magnetic material assures a high magnetic characteristics. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic material.

Conventionally, a sintered magnet having an Nd—Fe—B composition (hereinafter referred to as an Nd—Fe—B sintered magnet) is known as a magnet having high magnetic properties. Such an Nd—Fe—B sintered magnet usually needs to contain a heavy rare earth such as Dy, which is a rare resource, in order to improve heat resistance.
On the other hand, in recent years, from the viewpoint of depletion of resources, there is a demand for an alternative magnet for a Nd—Fe—B sintered magnet that does not need to contain a heavy rare earth such as Dy.

As such a magnet, a nitrogen-based magnet (for example, a magnet having an Sm—Fe—N-based composition) has been proposed. Nitrogen-based magnets have high potential and excellent magnetic properties, but are thermally unstable. Therefore, when sintered, the magnetic properties may deteriorate due to decomposition of the components of the nitrogen-based magnet.
Therefore, for example, a resin-bonded magnet compression-molded by mixing Sm ₂ Fe ₁₇ N _2.6 compound powder with 3% epoxy resin in a weight ratio to the powder and applying a pressure of 8 ton / cm ² has been proposed. (For example, refer to Patent Document 1).

JP-A-4-346203

However, since the resin-bonded magnet described in Patent Document 1 contains an epoxy resin, the molded body itself can be densely formed, but the density of the magnet component cannot be improved, and therefore sufficient magnetic properties can be obtained. There is a bug that you can not.
An object of the present invention is to provide a magnetic material that can be easily manufactured and has excellent magnetic properties.

  In order to achieve the above object, the magnetic material of the present invention is characterized in that magnet powder and metal glass are mixed and heated to a temperature equal to or higher than the deformation start temperature of the metal glass.

  According to the magnetic material of the present invention, high magnetic properties can be ensured by simple manufacturing.

The magnetic material of the present invention contains magnet powder and metallic glass. Examples of the magnet powder include a nitrogen-based magnet and a nanocomposite magnet.
In the present invention, the nitrogen-based magnet is not particularly limited, and examples thereof include a rare earth-transition metal-nitrogen-based magnet.
Examples of rare earth-transition metal-nitrogen based magnets include Sm—Fe—N based magnets, Sm—Fe—Mn—N based magnets, and preferably Sm—Fe—N based magnets.

The Sm-Fe-N-based magnet is a powder of a magnet having an Sm-Fe-N-based composition (hereinafter sometimes referred to as SmFeN), for example, pulverizing SmFeN obtained by a known method. Can be manufactured.
More specifically, for example, first, an SmFe alloy powder is produced from a samarium oxide and iron powder by a reduction diffusion method, and then the obtained SmFe alloy powder is obtained by, for example, N ₂ gas or NH ₃ gas. In an atmosphere such as a mixed gas of N ₂ and H ₂ , SmFeN is manufactured by heating at a temperature of 600 ° C. or lower, for example.

Thereafter, the obtained SmFeN is finely pulverized by a known pulverizer such as a jet mill or a ball mill. Thereby, an Sm-Fe-N magnet can be obtained.
Further, the Sm—Fe—N magnet can be manufactured without pulverizing SmFeN. In this method, for example, first, Sm and Fe are dissolved in an acid to obtain Sm ions and Fe ions, and then the solution is reacted with, for example, Sm ions and Fe ions to form an insoluble salt. Ions (for example, hydroxide ions, carbonate ions, etc.) are added to obtain a salt precipitate.

Thereafter, the obtained precipitate is fired to produce a metal oxide, and then the metal oxide is reduced. Thereby, an Sm-Fe-N magnet can be obtained.
Note that the Sm—Fe—N magnet is not limited to the above method, and can be manufactured by other known methods.
More specific examples of such Sm—Fe—N magnets include Sm ₂ Fe ₁₇ N ₃ (Curie point: 474 ° C.).

These nitrogen-based magnets can be used alone or in combination of two or more.
In addition, the decomposition temperature of a nitrogen-type magnet is 600 degreeC or more, for example. Furthermore, such a nitride magnet is gradually decomposed from, for example, 500 ° C. by heating to generate SmN, Fe, and the like.
Moreover, the volume average particle diameter of a nitrogen-type magnet is 1-20 micrometers, for example, Preferably, it is 2-4 micrometers.

When the volume average particle diameter of the nitrogen-based magnet is within the above range, the coercive force is good.
Moreover, as such a nitrogen-based magnet, a commercially available one can be used. For example, Z16 (Sm—Fe—N-based magnet (Sm ₂ Fe ₁₇ N ₃ ), decomposition temperature 600 ° C., volume average A particle diameter of 3 μm, manufactured by Nichia Corporation) can be used.
In the present invention, the nanocomposite magnet is not particularly limited, and examples thereof include Nd—Fe—B based nanocomposite magnets and Sm—Fe—N based nanocomposite magnets.

The Nd—Fe—B nanocomposite magnet is, for example, a powder of a nanocomposite magnet having an Fe / Nd—Fe—B structure, and is not particularly limited. For example, the Nd—Fe—B nanocomposite magnet can be manufactured by a rapid cooling method or the like. .
More specifically, in this method, for example, first, a molten metal alloy (Nd—Fe—B alloy) is rapidly cooled to produce a rapidly solidified alloy. Next, the obtained rapidly solidified alloy is heat-treated to disperse Fe fine particles inside the hard magnetic phase. Thereby, an Nd—Fe—B nanocomposite magnet can be manufactured. Further, the Nd—Fe—B nanocomposite magnet can be further pulverized and used as necessary.

Note that the Nd—Fe—B nanocomposite magnet is not limited to the above method, and can be manufactured by other known methods.
More specifically, examples of such Nd—Fe—B-based nanocomposite magnets include nanocomposite magnets of Fe and Nd ₂ Fe ₁₄ B (Curie point: 310 ° C.).
The Sm-Fe-N-based nanocomposite magnet is, for example, a powder of a nanocomposite magnet having a Fe / Sm-Fe-N-based structure, and is not particularly limited. And can be produced by applying pressure.

  More specifically, in this method, for example, an Sm—Fe—N magnet obtained by a known method is pressurized at a predetermined pressure using a discharge plasma sintering machine or the like, and pulsed for a predetermined time. Thereby, the Sm—Fe—N magnet can be partially decomposed, and the Fe crystal phase as the soft magnetic phase can be formed in the Sm—Fe—N single crystal phase as the high magnetic phase. . Thereby, an Sm—Fe—N-based nanocomposite magnet can be manufactured. Further, the Sm—Fe—N-based nanocomposite magnet can be further pulverized for use.

The Sm—Fe—N-based nanocomposite magnet is not limited to the above method, and can be manufactured by other known methods.
More specifically, examples of such Sm—Fe—N-based nanocomposite magnets include nanocomposite magnets of Fe and Sm ₂ Fe ₁₇ N ₃ (Curie point: 474 ° C.).

These nanocomposite magnets can be used alone or in combination of two or more.
In general, when a nanocomposite magnet is fired in the production of a magnetic material, the crystal becomes coarse and the coercive force decreases.
The temperature at which the crystal of the nanocomposite magnet becomes coarse is, for example, 600 ° C. or higher.
Moreover, the volume average particle diameter of a nanocomposite magnet is 30-300 micrometers, for example, Preferably, it is 50-150 micrometers.

When the volume average particle diameter of the nanocomposite magnet is in the above range, the magnetic particle filling rate is improved and the residual magnetic flux density is improved.
These magnet powders can be used alone or in combination of two or more.
In the present invention, metallic glass is an amorphous alloy that begins to deform (softens) at a temperature lower than the crystallization temperature, and has excellent magnetic properties. Such metal glass starts to be deformed (softened) by heating and then crystallizes.

The metal glass is not particularly limited, and a known metal glass can be used. Specific examples of the metallic glass include metallic glass having a rare earth element-iron-based composition (hereinafter referred to as rare earth element-iron-based metallic glass).
The rare earth element is preferably a light rare earth element from the viewpoint of resource depletion, and more specifically, for example, Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Examples include Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), and Gd (gadolinium).

These rare earth elements can be used alone or in combination of two or more.
The rare earth element is preferably Nd (neodymium).
Moreover, the rare earth element-iron-based metallic glass can preferably further contain elements (elements other than rare earth elements and iron) such as Al (aluminum).
The metal glass is preferably a metal glass having an Nd—Fe—Al-based composition (hereinafter referred to as “Nd—Fe—Al-based metal glass”).

By using Nd—Fe—Al-based metallic glass as the metallic glass, the residual magnetic flux density, coercive force and maximum energy product can be improved.
Such a metallic glass can be manufactured by, for example, a gas atomizing method.
More specifically, in this method, for example, a high-pressure jet gas (for example, helium gas, argon gas, nitrogen gas, etc.) is sprayed on the molten metal containing the above components, and the molten metal is rapidly cooled. Micronize. Thereby, the powder of metallic glass can be obtained. Further, the metal glass can be further pulverized and used if necessary.

In addition, metal glass is not limited to said method, It can manufacture by another well-known method.
The deformation start temperature of the metallic glass is, for example, 400 ° C. or higher, further 450 ° C. or higher, for example, 600 ° C. or lower, and further 500 ° C. or lower.
In the present invention, the deformation start temperature of the metallic glass can be measured by, for example, a discharge plasma sintering machine.

More specifically, in this method, the metal glass is heated at a constant rate of temperature increase (40 ° C./min) in a vacuum by a discharge plasma sintering machine and pressurized at a constant pressure (800 MPa) to increase the temperature. Measure the change in press displacement with respect to. At this time, the temperature at which the press displacement rapidly changes is defined as the deformation start temperature.
In addition, when the glass transition temperature of metal glass is known, the glass transition temperature can also be employ | adopted as a deformation | transformation start temperature.

Moreover, the volume average particle diameter of metallic glass is 0.01-100 micrometers, for example, Preferably, it is 0.01-10 micrometers.
When the volume average particle diameter of the metal glass is in the above range, the gap between the magnet powders can be filled with the metal glass, and the residual magnetic flux density, coercive force and maximum energy product are good.
These metallic glasses can be used alone or in combination of two or more.

In the present invention, in order to produce a magnetic material, first, magnet powder and metallic glass are mixed.
The blending ratio of the magnet powder and the metal glass is such that the magnet powder is, for example, 60 to 99 parts by mass, preferably 80 to 95 parts by mass with respect to 100 parts by mass of the total amount of the magnet powder and the metal glass. Glass is 1-40 mass parts, for example, Preferably, it is 5-20 mass parts.

The mixing is not particularly limited as long as the magnet powder and the metal glass can be sufficiently mixed. For example, a known mixing device such as a ball mill can be used.
In this method, the magnetic powder and the metal glass are preferably mixed in an inert gas (for example, nitrogen gas, argon gas, etc.) atmosphere.
Although it does not restrict | limit especially as mixing conditions, When using a ball mill (capacity 0.3L), rotation speed is 100-300 rpm, for example, Preferably, it is 150-250 rpm, and mixing time is, for example, 10 to 60 minutes, preferably 15 to 45 minutes.

Next, in this method, the mixture of the magnet powder and the metal glass is heated to a temperature equal to or higher than the deformation start temperature of the metal glass.
More specifically, in this method, for example, using a hot press apparatus, a discharge plasma sintering machine or the like, a mixture of magnet powder and metal glass is applied at a pressure of 20 to 1500 MPa, preferably 200 to 1000 MPa. Under conditions, it is heated to, for example, 0 to 200 ° C., preferably 10 to 150 ° C. higher than the deformation start temperature of the metallic glass, specifically 400 to 600 ° C., preferably 410 to 500 ° C. To do.

Thereby, the magnetic material containing magnet powder and metal glass can be obtained.
Although heating is not particularly limited, for example, heating can be performed at a constant temperature increase rate from room temperature. In such a case, the temperature increase rate is, for example, 10 to 200 ° C./min, preferably 20 to 20 ° C. 100 ° C./min.
In the production of the magnetic material, if necessary, the mixture of the magnet powder and the metallic glass can be maintained for a predetermined time under high temperature conditions, continuing from the above heat treatment.

In such a case, after said heat processing, it hold | maintains at 400-600 degreeC, for example, preferably 410-500 degreeC, for 1 to 120 minutes, Preferably, it is 10 to 60 minutes.
Thereby, the magnetic characteristics of the obtained magnetic material can be further improved.
In the production of a magnetic material, for example, a mixture of magnet powder and metallic glass can be pressurized in a magnetic field.

When pressed in a magnetic field, the magnetic powder can be oriented in a predetermined direction, so that the magnetic properties of the obtained magnetic material can be further improved.
In the magnetic material thus obtained, the material deterioration caused by firing the magnet powder, more specifically, the generation of SmN, Fe, etc. by the decomposition of the nitrogen-based magnet, the crystal of the nanocomposite magnet, While coarsening and the like are suppressed, a gap (gap) between magnet powders is filled with metallic glass having excellent magnetic properties.

Therefore, according to such a magnetic material, high magnetic characteristics can be ensured by simple manufacturing.
Therefore, this magnetic material can improve the magnetic characteristics as compared with a resin bonded magnet containing a resin (for example, an epoxy resin).

Next, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited by the following Example.
Production Example 1 Production of Metallic Glass (Nd ₆₀ Fe ₃₀ Al ₁₀ ) Nd ₆₀ Fe ₃₀ Al ₁₀ was produced by a gas atomization method (injection gas: Ar) and then finely pulverized by a ball mill (LP-1 manufactured by Ito Seisakusho). Accordingly, the volume average particle diameter of 1 [mu] _m, to obtain a powder of Nd ₆₀ Fe 30 _{Al 10.}

The obtained Nd ₆₀ Fe ₃₀ Al ₁₀ powder was heated and pressurized with SPS (discharge plasma sintering machine, manufactured by SPS Syntex) under vacuum (5 × 10 ⁻² Pa), and the press displacement with respect to temperature By measuring the deformation start temperature of Nd ₆₀ Fe ₃₀ Al ₁₀ , the deformation start (softening) temperature was 400 ° C. The measurement conditions of the deformation start temperature are shown below.

SPS type: Carbide type (sample filling part size: 8x6mm)
Sample filling amount: 1.5 g
Temperature increase rate: 40 ° C./min Applied pressure: 800 MPa
Example 1
Nd ₆₀ Fe ₃₀ Al ₁₀ powder obtained in Production Example 1, Z16 (magnet powder, Sm-Fe-N magnet (Sm ₂ Fe ₁₇ N ₃ ), decomposition temperature 600 ° C., volume average particle diameter 3 μm, day Ada Chemical Industries, Ltd.) is blended so that Nd ₆₀ Fe ₃₀ Al ₁₀ is 5% by mass based on the total amount thereof, and in a nitrogen atmosphere, a ball mill (LP-1 capacity 0.3 L manufactured by Ito Seisakusho) For 30 minutes at 250 rpm.

Thereafter, 0.5 g of the obtained mixture of Nd ₆₀ Fe ₃₀ Al ₁₀ and Z16 was collected and filled in a mold (size: 5 mm × 5 mm, cemented carbide mold), and a discharge plasma sintering machine (SPS thin film) The pressure was increased to 1000 MPa by Tex Co., Ltd., heated to 420 ° C. over 10 minutes, and then allowed to cool. As a result, a magnetic material was obtained.
Example 2
A magnetic material was obtained in the same manner as in Example 1 except that heating (heating) to 420 ° C. and holding at 420 ° C. for 30 minutes were performed.

Comparative Example 1
A magnetic material was obtained in the same manner as in Example 1 except that Nd ₆₀ Fe ₃₀ Al ₁₀ powder was not blended.
Evaluation About each magnetic material obtained by each Example and the comparative example, the demagnetization curve was measured in VSM (made by Tamagawa Seisakusho), and those magnetic characteristics were evaluated. The results are shown in Table 1.

In the table, Br represents the residual magnetic flux density, bHc represents the coercive force (B coercive force), iHc represents the coercive force (I coercive force), and BHmax represents the maximum energy product.
Moreover, as for these, all show that a magnetic characteristic is so favorable that the value is high.

Claims (1)

  A magnetic material characterized in that magnet powder and metal glass are mixed and heated to a temperature equal to or higher than the deformation start temperature of the metal glass.