JPH0475302A - R-fe-b bond magnet production method - Google Patents

Abstract

PURPOSE:To establish a method for reducing or eliminating the strain that occurs when an R.Fe.B based isotropic or anisotropic powder is mixed with a binding material by using a metal or alloy powder as the binding material and thereby attaining excellent magnetic characteristics. CONSTITUTION:A base alloy, which consists (wt.%) of Fe:65.8, Nd:29.8, Co:2.65, Pr:0.8, B:0.95 and is combined through the high-frequency induction melting method, is formed into a liquid quench thin sheet using a single roller in an Ar atmosphere. Next, a vibration mill is used to produce particles with an average size of 150mum. After this, vacuum heat treatment is performed for 1 hour at 700 deg.C to obtain an isotropic base powder. After 15vol% of annealed, 99.9% pure Cu powder (-500 mesh) is added to this base powder and mixed, the resulting mixed powder is placed in a die and formed under a pressure of 7ton/cm<2>. Heat treatment follows for 30 minutes in an Ar atmosphere at a temperature between 200 deg.C--950 deg.C. Changes in magnetic and strength characteristics are examined before and after this heat treatment.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing an R-Fe-B bonded magnet (where 1R is a rare earth element containing Y), and more specifically, relates to a method for producing an R-Fe-B bonded magnet (where 1R is a rare earth element containing Y), and more specifically, in a bonded state. The present invention relates to a method that allows arbitrary heat treatment to improve characteristics.

[Prior Art] In recent years, a material obtained by subjecting a powder obtained by subjecting a thin ribbon obtained by rapid solidification of a master alloy containing rare earth elements (particularly Nd), Fe, and B as main components to a suitable heat treatment to magnetically Has isotropy,
It is known to exhibit a high energy product, and its pulverized powder is generally referred to as R.Fe-B isotropic powder.

On the other hand, a powder obtained by crushing a laminate made of rapidly solidified powder and hot-formed and then hot-upgraded exhibits extremely strong magnetic-fishing properties, compared to the isotropic powder described above. It was found to exhibit a higher maximum energy product (BH) MAX.

As an applied product, so-called anisotropic bonded magnets, which are obtained by molding and solidifying a mixture of the same powder and a small amount of a binder into an arbitrary shape, are being developed, and these two types of powder have different characteristics. Taking advantage of its characteristics and performance, it has begun to be used in various fields.

On the other hand, the development of bonded magnets with even higher performance is also active, and studies are underway from the following viewpoints.

(1) Improving the performance of the magnetic powder used.

(2) Reducing and preventing deterioration of magnetic properties due to orientation disturbance that inevitably occurs during molding.

3) Reducing and preventing deterioration of magnetic properties due to distortion that inevitably occurs during molding.

Regarding (1) above, for example, the alloy composition including additives, and the conditions for producing the rapidly solidified ribbon.

Further improvements are being made through improvements in upsetting processing conditions, etc.

Regarding (2) above, there is a problem related only to anisotropic powder, but when producing powder from the bulk after hot upsetting, a pulverization method that also takes into account the orientation during compaction, specifically, Establishment of a method for producing powder exhibiting a spherical shape and patent application No. 1-3
Attempts have been made to produce granulated powder as disclosed in No. 36379, and improvements have been steadily made.

However, as a measure to prevent characteristic deterioration due to strain as described in (3) above, studies are being conducted on molding methods such as controlling the powder shape and adding lubricant to make it less susceptible to strain. In the process of increasing the filling rate of a molded body using high pressure, the occurrence of distortion is inevitable, and no fundamental preventive measures have been found. By the way, this distortion problem occurs with Sm-C, which was developed earlier.

This is a common problem in bonded magnets as well, and the countermeasures are 1. For example, as disclosed in Japanese Patent Application Laid-Open No. 64-69002, a material with high heat resistance such as water glass is used as a binder between magnetic powders. There is a method in which a bonded magnet is manufactured using a bonded magnet and then subjected to heat treatment at a high temperature to remove distortion and restore characteristics.

[Problems to be Solved by the Invention] The present inventor also investigated whether a similar method could be applied to R-Fe-B type (R is a rare earth element containing Y such as Nd) bonded magnets. Results of two types of molded bodies: (i) a molded body containing only magnetic powder without the addition of a binder (if) a molded body in which water glass was added as a binder to magnetic powder; after fabrication, heat treatment was performed to remove distortion.

Although a marked improvement in the magnetic properties after molding was observed in the molded product (i) to which no binder was added.

In molded bodies having a binder (if), there is a problem in that the reaction between the binder and the magnetic powder significantly deteriorates the magnetic properties, and in the case of thin-walled molded bodies, warpage occurs.

Problems with the occurrence of cracks have been observed in molded bodies with a square thick-walled shape, and similar problems have been observed in binders with high heat resistance other than water glass, resulting in the occurrence of cracks during molding. Measures against distortion have not yet been established.

Therefore, one technical problem of the present invention is to establish a method for reducing or eliminating the strain that occurs when molding a mixture of R-Fe-B-based isotropic or anisotropic powder and a binder, and to achieve excellent magnetic properties. It is an object of the present invention to provide a method for manufacturing an R-Fe-B bonded magnet exhibiting characteristics.

[Means for Solving the Problems] The present invention has been developed based on the above-mentioned test results for removing strain from molded bodies through heat treatment.(i) Reactivity with binder.

(11) Based on the fact that if the problem of warping and single cracking of molded objects can be overcome, it is possible to definitely expect the effect of improving magnetic properties, this was discovered as a result of various studies and tests of new binding materials. It is something that

According to the present invention, a mixture of R-Fe-B (where R is a rare earth element containing Y) powder and a binder is compression molded to produce an R-Fe-B bonded magnet. In the method, a method for producing an R.Fe-B bonded magnet is obtained, characterized in that a metal or alloy powder is used as the binder.

According to the second aspect of the present invention, in the method for manufacturing an R-Fe-B bonded magnet, the metal or alloy powder as the binder is an ultrafine powder.
A method for manufacturing a bonded magnet is obtained.

Furthermore, according to the present invention, any of the above-mentioned R.Fe-
In the method for manufacturing B-based bonded magnets, after compression molding, 30
A method for manufacturing an R-Fe-B bonded magnet is obtained, which is characterized in that heat treatment is performed within a temperature range of 0°C to 900°C.

That is, 1. The greatest feature of the present invention is that ultrafine metal powder, soft metal powder, or alloy powder is used as a binder between magnetic powders, and as a result, (i) reactivity with magnetic powder in high temperature regions is reduced. Without.

Even if a reaction occurs, if it is small, the deterioration in magnetic properties will be extremely small compared to the effect of restoring the properties by removing strain.

(11) Since the binder is the same metal as the magnetic powder, the expansion coefficient is almost the same, and there is no occurrence of warping, cracking, etc., and it can sufficiently withstand rapid cooling after heat treatment, and at the same time, there is no slight distortion etc. It was confirmed that it could sufficiently withstand rapid cooling after heat treatment, and at the same time had enough flexibility that slight distortions could be corrected by sizing after heat treatment.

In addition, when using ultrafine powder metal as a binder, the greatest concern was the strength of the compact, but ultrafine powder metal generally has (a) a large specific surface area.

(b) It has the characteristics that powder binding progresses easily in a low temperature range of about 200°C, and as a result, there is entanglement with magnetic powder during molding and during subsequent heat treatment. It has a tremendous binding effect, making it possible to achieve molded body strength equivalent to that of conventional organic binders.

Incidentally, the evaporation method is a common method for producing ultrafine metal powder, and mass production of powder with a particle size of about 20 rv has already been established.

In the present invention, an ultrafine powder is a powder with a particle size of several tens of nanometers (nanometers), which can be observed with a transmission electron microscope, and whose physical properties are of an order in which properties unique to the substance begin to dominate. call.

In addition, the ultrafine powder metal that can be specifically used at present is (
: There are u, Fe, Ag, Ni, etc.

On the other hand, when using metal or metal powder as a binder, the greatest concern was the strength of the compact, and the significance of the present invention depends on how to ensure performance comparable to conventional organic binders. It was a matter to be decided.

A solution was found by employing powders of metals and alloys that have soft properties compared to magnetic powders, specifically Cu softened by annealing.

Ag, Al, Fe, Ni, Co, Cu-Zn alloy, Fe
When powders such as -Ni alloy and duralumin were used as a binder, molded bodies having strength equal to or higher than conventional organic binders were obtained.

Next, the heat treatment temperature of the molded body needs to be carried out in a temperature range where strain can actually be recovered and which does not change the crystal structure of the magnetic powder.
The optimum condition is a range of 0° C. or lower; at temperatures lower than this, no strain removal effect is observed, and at temperatures exceeding this, the properties of the powder itself deteriorate.

In the present invention, the effects of isotropic and anisotropic powders of the R-Fe-B system (where R is a rare earth element containing Y) have been shown, but for example, Nd is used as R.

When this Nd is replaced with a rare earth element such as Dy or Pr.

Needless to say, when a part of Fe is replaced with Co, alloy systems in which various other additives are added are not a constraint for carrying out the present invention.

Similarly, the ultrafine powder metal used should not be a constraint as long as it satisfies the function as a binder.

[Example code] Next, the effectiveness of the present invention will be shown with examples.

Example 1 Composition (vt%) of Fe: 65.
8. Nd: 29.8. Co; 2.85. P
A mother alloy adjusted to r: 0.8 and B: 0.95 was prepared into a liquid quenched ribbon using a single roll device in an Ar atmosphere, and then a vibration mill was used to make the average grain size 150μ. After adjusting as described above, vacuum heat treatment was performed at 700° C. for 1 hr to produce a 2-isotropic raw material powder.

Next, 15vo! % after addition and mixing.

After inserting the mixed powder into the mold, molding pressure cuff ton/c-
The molding was done with. The subsequent heat treatment is performed at a temperature of 200° C. to 950° C. for 30 minutes in an Ar atmosphere.

Characteristic changes before and after heat treatment were evaluated for magnetic property 1 strength. As comparative materials, a bonded magnet using a conventional organic material as a binder and a molded article without using a binder were used. A series of results are shown in Table 1.

Example 2゜A bulk body made from the liquid quenched ribbon produced with the composition of Example 1 and subjected to hot opening molding and hot upsetting was pulverized using a disk mill to obtain an anisotropic powder with an average particle size of 170μ. Created. Next, Cu + A g + A I rF e , N with a purity of 99.9% or more was annealed with the same powder.
1 + CO + powder was added at 15vol% and mixed, and after inserting each of the mixed powders into a mold, an applied magnetic field of 1 was applied.
Parallel magnetic field molding was performed at a molding pressure of 5 kOe and a molding pressure of ton/cd to produce six types of anisotropic bonded magnets.

Further, each bonded magnet was heat treated within a temperature range of 300°C to 900°C for a predetermined time.

As a result 1, the bonded magnet of Example 2 of the present invention had a resistance strength equal to or higher than that when a conventional organic binder was used, and also exhibited the highest value in terms of magnetic properties.

Example 3゜ Using a mixture of isotropic powder and Cu powder produced according to the conditions of Example 1 as raw materials, a ring with an outer diameter of 20 + + + s, an inner diameter of 18, and a height of 15 m + * and a diameter of 40 r.
A thick disk with a height of 20 degrees was prepared,
It was confirmed that no defects such as warping or cracking were observed in the appearance of the molded product after heat treatment.

Example 4 Composition (wt%) of Fe85.
8. Nd: 29.8. Co:2.65.
A liquid quenched ribbon was produced using a single roll device capable of replacing a master alloy with P r :0.8 and B20.95 in an Ar atmosphere.

Next, the average particle size was adjusted to 150 μm using a vibration mill, and then vacuum heat treatment was performed at 700° C. for 1 hr to produce an isotropic raw material powder.

Next, 10 vol of pure Cu ultrafine metal powder with an average particle size of 20 na produced by low-pressure gas evaporation method was added to the same powder.
After adding 1% and stirring with a mold mixer under an Ar atmosphere, the powder was inserted into a mold and a molded body was produced using a molding pressure cuff of ton/cd. Next, the molded body was heat treated for 200 min in an Ar atmosphere.
The heat treatment was carried out for 30 minutes at a temperature in the range of .degree. C. to 950.degree. C., and the characteristics before and after the heat treatment were evaluated in terms of magnetic properties and strength. As comparison materials, a bonded magnet using a conventional organic material as a binder and a molded body without using a binder were used.

A series of measurement results are shown in Table 3.

Example 5゜Using the liquid quenched ribbon produced with the composition of Example 4 as a raw material,
The bulk body subjected to hot open molding and hot upsetting was pulverized using a disk mill to produce anisotropic powder with an average particle size of 170 μm.

Next, 10vol.1% of the same powder was added with Ag (average particle size 20 rv) prepared by the resistance heating method, and ultrafine powder metals such as Fe and Ni (average particle size 20 nm) prepared by the plasma jet method. After mixing in the same manner as described above, the mixed powder was inserted into a mold.

Parallel magnetic field molding was performed with an applied magnetic field of 15 kOe and a molding pressure of cuff ton/cj to produce an anisotropic bonded magnet. or.

The heat treatment was performed at a temperature of 300°C to 900°C for a predetermined time.

As a result, the resistance strength remained at the same level or higher than when conventional organic binders were used, and the highest value in terms of magnetic properties was obtained. The heat treatment conditions and characteristic values at this time are shown in Table 4.

Example 6゜A thin-walled ring with an outer diameter of 20 mm, an inner diameter of 18 m+s, and a height of 15 II 11 and a diameter of 40 mm was made using a mixture of isotropic powder and pure Cu ultrafine powder produced under the same conditions as in Example 4 as raw materials. When a thick-walled disc having a height of 20 mm was produced and heat treated, it was confirmed that no defects such as warping and cracking were observed in the appearance of the molded product.

Below is the margin [Effects of the invention] As is clear from the above explanation, 1.
According to the method for manufacturing B-series bonded magnets, a method has been established to remove the strain that inevitably occurs during molding of magnetic powder, and as a result, bonded magnets that exhibit high magnetic properties and high strength can be easily and inexpensively manufactured. This makes it possible to make a significant contribution to industry.

*Data after forming diameter

Claims (3)

[Claims] 1. R. Fe/B system (however, R is a rare earth element containing Y)
A mixture of powder and binder is compression molded to form an R.
A method for manufacturing an R/Fe/B bonded magnet, characterized in that a metal or alloy powder is used as the binder. 2. The method for manufacturing an R.Fe.B bonded magnet according to the first claim, wherein the metal or alloy powder as the binder is an ultrafine powder. Production method. 3. In the method for manufacturing an R.Fe.B bonded magnet according to the first or second claim, after compression molding,
R・F characterized by heat treatment within a temperature range of 0°C
A method for producing an e/B bonded magnet.