JPH02257603A - Bonded magnet - Google Patents

Abstract

PURPOSE:To form an anisotropic bonded magnet only by a simple process by a method wherein a specific magnetic material is contained. CONSTITUTION:A magnetic material expressed by a formula of RealphaFe(100-alpha-beta-gamma) NbetaHgamma is contained. In this formula Re represents at least one kind out of rare- earth elements including Y; alpha, beta and gamma represent 5<=alpha<=20, 5<=beta<=30 and 0.01<=gamma<=10, respectively, in terms of their atomic %. A pulverulent body of this magnetic material is kneaded with a binder; after that, this mixture is compressed or injection-molded in a magnetic field or in a state that the magnetic field does not exist; alternatively, after a powdered molded substance has been formed in the magnetic field, it is impregnated with the binder or pressed and formed. Thereby, it is possible to form an anisotropic bonded magnet by a simple and easy method.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a bonded magnet manufactured using magnetic powder having a box-earth-iron-nitrogen-hydrogen composition that does not cause a decrease in coercive force even when it is atomized. Regarding.

[Prior Art] The demand for higher performance of permanent magnets has been increasing in recent years. Conventionally, high-performance magnets have been limited to sintered magnets, and their maximum energy <(Bit)...> product is, for example, 208 GOc or more for Sm-Co magnets, and
The system magnet has reached 35-40 MGOc or more. However, sintered magnets are prone to cracking and chipping due to mechanical stress, and have poor formability. Also, there are many relatively heavy shrines.

On the other hand, plastic magnets (brafugu) or bonded magnets are composite materials that combine magnetic powder and synthetic rubber or plastic powder, and although their magnetic properties are reduced to 1/2 to 1/3 that of sintered magnets, they are easier to work with. In addition to being capable of molding complex-shaped products and combining with different materials, it also has great advantages in terms of cost and process.

Bonded magnets are broadly divided into compression molding and injection molding, and synthetic rubber, nylon, epoxy resin, etc. have been used as binders.

As a bonded magnet made by injection molding, S is used as a magnetic powder.
mCos, Sm2Ca+r, etc. are used, and these are kneaded with PBT (polybutylene terephthalate), PP5 (polyphenylene sulfide), and a liquid crystal polymer, granulated, and then injection molded in a magnetic field.

As a bonded magnet made by compression molding, N is used as magnetic powder.
d-Fe-B is often used, and epoxy, phenolic resin, etc. are often used as binders. This is produced by compression molding in a magnetic field and then heat curing.

In general, injection molded bonded magnets are superior in terms of process and application, but compression molded magnets are superior in terms of physical properties, especially high magnetic properties.

Regarding magnetic properties, regardless of whether Sm-Co or Nd-Fe-B is used, in order to obtain high magnetic properties, heat treatment of magnetic powder or molding technology during bonded magnet molding is important. . For example, in the Sm--Co system, multi-stage aging treatment of the master alloy is required, and a bonded magnet with a maximum energy product of about 13 to 17 MGOc is expensive.

On the other hand, in the Nd-Fe-B system, the bulk properties are lost due to fine pulverization, and the holding force is significantly reduced (ni
l) □, the value becomes small. However, IJ% isotropic bonded magnets have been put into practical use, and (Bll)...
is approximately 6-1 OMGOe.

A magnet using this magnetic powder has more than 10 MGOe (B
ll)3. In order to obtain , it is necessary to create a powder with high physical properties and anisotropy by hot pressing or compression anisotropy process, and to create an anisotropic bonded magnet, but it is difficult to put it into practical use. There are many.

[Problems to be Solved by the Invention] The present invention utilizes the high magnetic properties of the powder, which are the characteristics of the novel magnetic material of the rare earth-iron-nitrogen-hydrogen system disclosed in the prior application17.
Therefore, the present invention aims to provide an anisotropic bonded magnet that can be manufactured using only r11 simple steps.

[Means for Solving the Problems] The bonded magnet of the present invention for solving the above problems has the following general formula: (1) Re, FefloO-a-1-y
A bonded magnet containing a magnetic material represented by l N s Hv.

However, Re is at least one rare earth element including Y, and α, β, and γ are the respective atomic percentages of 5≦α≦20 5≦β≦30 0.01≦γ≦l0 (2) Components of magnetic material (1,1)1~50 of certain Fe
Replacement of atomic % with Co1. The bonded magnet according to claim (1) above.

In order to manufacture the bonded magnet of the present invention, the above-mentioned claim (1) is required.
Alternatively, in (2), the powder of the magnetic material is kneaded with a binder and then compressed or injection molded in a magnetic field or in the absence of a magnetic field, or the compact is produced in a magnetic field and then impregnated with a binder or press-fitted. is preferred.

Here, compression molding refers to mixing magnetic powder and a binder, placing it in a mold, compressing and molding in a magnetic field, and heating and hardening the binder.Injection molding refers to heating and kneading the same mixture. l- refers to injection molding in a magnetic field using a mold after granulation. Note that the magnet after molding is demagnetized or magnetized as necessary. In addition, in the case of bonded magnets in which a powder compact is produced and pinter is impregnated or press-fitted into it, anisotropy, isotropy, etc. Although any type of bonded magnet can be manufactured, we will show here that an anisotropic bonded magnet can be manufactured using a simple method.

Manufacturing Method The steps of manufacturing a bonded magnet in the present invention are shown in FIG.

(1) In the synthesis of the master alloy, a rare earth-iron alloy is synthesized.

(2) Coarse pulverization, (3) Nitriding and hydrogenation to produce magnetic powder (RFN) in the present invention.
H-based magnetic powder) can be produced.

(4) Fine pulverization is mainly a coercive force optimization process.

(5) There are mainly three methods for manufacturing bonded magnets.

Each of these steps will be explained below.

(1) Synthesis of master alloy The raw material alloy can be produced by a high frequency furnace, an arc melting furnace, or by a liquid super-quenching method. Its composition is Re 5~
It is preferable that Fe is in the range of 25 at% and 75 to 95 at%. When Re is less than 5 at%, α-Fe is present in the alloy.
There are many phases and high coercive force cannot be obtained. Furthermore, if Re exceeds 25 atomic %, a high saturation magnetic flux density cannot be obtained.

When a high frequency furnace or an arc melting furnace is used, Fe tends to precipitate when the alloy solidifies from a molten state, which causes a decrease in magnetic properties, particularly coercive force. Therefore, it is effective to perform annealing for the purpose of eliminating the phase of Fe alone, making the alloy composition uniform, and improving crystallinity. This annealing is most effective when performed at 1000°C to 1800°C. The alloy produced by this method has better crystallinity and higher saturation magnetization than those produced by the liquid ultra-quenching method.

Alloys with the desired composition can also be produced using alloy production methods such as the liquid super-quenching method and the roll rotation method. Moreover, the crystal grains of the alloys produced by these methods are fine, and submicron particles can be prepared depending on the conditions. However, when the cooling rate is high, the alloy becomes amorphous, and even after nitriding and hydrogenation, the saturation magnetization and coercive force do not increase as much as with other methods. In this case as well, post-treatment such as annealing is required.

(2) Coarse pulverization The pulverization at this stage may be performed using a method such as a Shaw Crusher stamp mill that prepares only coarse powder, or may be performed using a ball mill or jet mill depending on the conditions. However, this pulverization is for the purpose of uniformly performing the nitriding and hydrogenation in the next step, and it is necessary to prepare a powder state that has sufficient reactivity and does not progress to oxidation. is important.

(3) Nitriding and Hydrogenation A method for combining or impregnating nitrogen and hydrogen into the pulverized raw material master alloy is to pressurize or heat-treat the raw material alloy powder in ammonia gas or a reducing mixed gas containing ammonia gas. The method is valid. The amount of nitrogen and hydrogen contained in the alloy can be controlled by the mixture component ratio of the ammonia gas-containing mixed gas, heating temperature, pressurizing force, and treatment time.

As the mixed gas, a mixture of hydrogen, helium, neon, nitrogen, and argon, or a mixture of two or more of them and ammonia gas is effective. Although the mixing ratio can be changed depending on the treatment conditions, it is particularly effective to use ammonia gas partial pressure of 0.02 to 0.75 atm, and the treatment temperature is preferably in the range of 200 to 700°C. At low temperatures, the penetration rate is low, and at high temperatures of 700° C. or higher, iron nitrides are produced, and the magnetic properties deteriorate. In the pressure treatment, the contents of nitrogen and hydrogen can be changed even with a pressure of about 1 Oate.

The point to be careful about in this nitriding and hydrogenation process is oxidation.
Magnetic properties deteriorate if oxygen is present in the atmosphere.

Therefore, it is necessary to lower the oxygen partial pressure as much as possible.

If a gas other than ammonia gas is used as the main component of the nitriding or hydrogenation atmosphere, the reaction efficiency will be significantly reduced. However, it is possible to introduce nitrogen and hydrogen, for example, by carrying out a long reaction using a mixed gas of hydrogen gas and nitrogen gas.

(4) The coarse powder after pulverization, nitriding and hydrogenation has a saturation magnetization of 13KG as it is.
, has a coercive force of 500 to 7000c, but by grinding it with a vibrating ball mill, a Yukon ball mill, and a rotary ordinary pot-type ball mill, the coercive force can be reduced to 8.
It is possible to improve it to about 0000c. Normally, the magnetization decreases to some extent, but powder having the required magnetization and coercive force can be obtained by setting these pulverization conditions.

(5) Bonded magnet production Here, three typical methods for producing bonded magnets using RFNH-based magnetic powder will be shown. However, the details of the process, such as the process of magnetic field orientation, are not limited to these.

(A) Compression molding After adjusting the magnetic properties of the RFNH magnetic powder, it is mixed with a binder such as epoxy resin, phenol resin, or synthetic rubber, and the required amount is transferred into a mold and compression molded in a magnetic field. After this is heated and hardened, it is removed from the mold and is made into celadon or demagnetized to form the final molded magnet.

(B) After adjusting the magnetic properties of injection molded RFNH-based magnetic powder, polyamide,
After mixing with polybutylene terephthalate, polyphenylene sulfide, liquid crystal polymer, etc., it is kneaded, granulated, and then injection molded using a mold. This molded body is magnetized or demagnetized to form a molded magnet.

(C) Powder Molding After adjusting the magnetic properties of the RFNH-based magnetic powder, it is pressure molded using a mold in a magnetic field. This molded body is taken out, and the polymer or a mixture of the polymer and its curing agent is dissolved in a soluble solvent such as toluene, ethanol, or cyclohexane, impregnated or press-fitted into the molded body, and then the solvent is evaporated. dry. This is magnetized to form an anisotropic bonded magnet.

[Example code] The present invention will be specifically explained below using examples.

Example 1 An alloy with a composition of Sm11Fe87 was produced by high frequency melting method,
This synthesis was annealed at 1250° C. in an Ar atmosphere for about 3 hours, and S m lo, 5F e 89. A master alloy was prepared.

This master alloy is coarsely ground to about 100 μI,
Ammonia-hydrogen atmosphere [NH3(20)-H2(8
0) 1 By introducing N and H into the structure at 465°C, S m
s, 5 F e 72. , N , 7H2□ magnetic powder is produced. This powder was annealed at 465°C in H2, further annealed at 150°C in the atmosphere, and finely pulverized in a vibrating ball mill to give a saturation magnetization of 12KG.

Magnetic powder with a coercive force of 45,000e was obtained.

Add 0.5g of this powder and epoxy adhesive (2-component hot type) to 0.0g.
．． Mix 4g, transfer this to a ceramic mold, let one harden for 50 minutes, and the other 15KO.
Cure for 50 minutes in a magnetic field of e.

These compacts were magnetized in a magnetic field of 15 KOe and measured using a vibrating sample magnetometer (VSM device).

``J3 magnet was performed at 80) [Oc.

Example 3 The powder of Example 1 and the method for producing this powder, the mother alloy in which 50 at. The alloy was subjected to the same treatment as in Example 1, and a 4g1 magnet having the composition and magnetic properties shown below was treated at 60KOc.

Example 2 Using the powder of Example 1, 100 g of this powder and 50 g of 8-nylon were kneaded, cut into cylindrical chips of 5 to IOam, and molded with an injection molder at 250°C in a nitrogen atmosphere to a size of 3 mm.
The mixture was poured into a mold having a cross section of 812 mm to obtain a rod-shaped molded product.

Coercive force (Idle) 4.7KOe Residual magnetization (Br
) 6.5KOe (Bll) , , , 6.3MGOe 0.5g each of these powders were heated at 10ton/min in a magnetic field of 15KOc.
It was made into a powder compact of 5+ m and 5 m 1 IX lOmn+X in cm 2 . On the other hand, 5 wt% in toluene
Impregnated with dissolved Inbrene rubber and dried.

This was magnetized in a magnetic field of 60 KOe. A bonded magnet with the following characteristics was obtained.

[Effect of the invention] As explained above, the rare earth (Re) iron (Fe) of the present invention
)-Nitrogen (N)-Hydrogen (H) based magnetic material (RFNH magnetic powder) can be finely pulverized without damaging magnetic anisotropy, coercive force, etc. Heat treatment is required to immediately develop high magnetic properties upon introduction.
It is also possible to wipe the hot press etc.

[Brief explanation of drawings] FIG. 1 is a manufacturing process diagram of the bonded magnet of the present invention.

Claims (2)

[Claims] (1) General formula Re_αFe_(_1_0_0_−_α_
A bonded magnet containing a magnetic material represented by β_γ_)N_βH_γ. However, Re is at least one rare earth element including Y, and α, β, and γ are each atomic percentage of 5≦α≦20 5≦β≦30 0.01≦γ≦10 (2) Claim (1) above, characterized in that 0.01 to 50 atomic % of Fe, which is a component of the magnetic material, is replaced with Co.
Bonded magnet as described.