JPH0340082B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to the production of an alloy powder for permanent magnets whose main components are R (where R is at least one rare earth element including Y), B, and Fe. Regarding the method, R
-Using the H ₂ occlusion property of B-Fe alloy ingots for magnets, rare earth/boron/iron based permanent magnet alloy powder can be naturally disintegrated in an H ₂ atmosphere to efficiently obtain alloy powder in a short time. Regarding the manufacturing method.

BACKGROUND ART Permanent magnetic materials are one of the extremely important electrical and electronic materials used in a wide range of fields, from various household appliances to peripheral terminal equipment for large computers. With the recent demand for smaller size and higher efficiency of electrical and electronic equipment, permanent magnet materials are required to have increasingly higher performance.

Current typical permanent magnet materials are alnico, hard ferrite and rare earth cobalt magnets. As the cobalt raw material situation has become unstable in recent years, the demand for alnico magnets containing 20 to 30 wt% cobalt has decreased, and inexpensive hard ferrite, whose main component is iron oxide, has become the mainstream magnet material. Summer.

On the other hand, rare earth cobalt magnets contain cobalt from 50 to
It is very expensive because it contains 60wt% and uses Sm, which is not included in rare earth ores.
Compared to other magnets, the magnetic properties are much higher,
It has come to be used mainly for small, high value-added magnetic circuits.

Therefore, the present inventor first developed R as a new high-performance permanent magnet that does not necessarily contain expensive Sm or Co.
-B-Fe system (R is at least one rare earth element including Y) proposed permanent magnet (Patent application 1983-
No. 145072).

Furthermore, in order to improve the temperature characteristics of permanent magnets made of magnetically anisotropic sintered bodies of the R-B-Fe system, some of the Fe is replaced with Co, thereby increasing the Curie point of the resulting alloy. We proposed a permanent magnet made of an anisotropic sintered R-B-Fe-Co system with improved temperature characteristics (Japanese Patent Application No. 166663/1983).

These R-B-Fe permanent magnets have Nd as R.
It is an excellent permanent magnet that uses light rare earths, which are abundant in resources, mainly Fe and Pr, and exhibits an extremely high energy product of 25 MGOe or more, with Fe as the main component.

Problem to be solved by the invention The above novel R-B-Fe system, R-B-Fe-Co
system (R is at least one rare earth element including Y
The rare earth metal that is the starting material for manufacturing permanent magnets is generally a metal lump produced by Ca reduction method or electrolysis method, and using this rare earth metal lump, for example, the following process permanent magnets are manufactured.

As a starting material, electrolytic iron with a purity of 99.9%,
Feroboron alloy containing 19.4% B and the remainder consisting of Fe and impurities such as Al, Si, and C, purity 99.7%
Rare earth metals of more than 99.9% purity
of electrolytic Co is melted by high frequency, and then cast into a water-cooled copper mold. Coarsely pulverized with a stamp mill to 35 mesh through, and then ground with a ball mill for, for example, 6 hours to form a fine powder of 3 to 10 μm. Oriented in a magnetic field (10kOe) and molded (1.5t/cm ²
Sintering, for example, at 1000° C. to 1200° C. for 1 hour in Ar, followed by cooling.

As mentioned above, the alloy powder for permanent magnets of the present invention can be obtained by mechanically pulverizing and finely pulverizing an ingot of the desired composition, but this alloy for magnets is extremely difficult to crush, and coarse pulverization is only suitable for flat pulverization. In addition, it is difficult to mass-produce the 35 mesh through powder required for the next fine grinding process, and the yield of coarsely ground powder and grinding efficiency are low. There were problems such as poor quality.

The purpose of the present invention is to provide a method for producing an R-B-Fe alloy powder for permanent magnets, which can efficiently grind the R-B-Fe alloy powder in a short time, and which can be produced at low cost and with a high powder yield. It is said that

Means for Solving the Problems This invention provides R (where R is at least one kind of rare earth elements including Y) 10 atomic % to 30 atomic %, B2 atomic % to 28 atomic %, Fe65 atomic % to 82 atomic %. After breaking an ingot having a tetragonal crystal structure with atomic percent as its main component so that the metal surface is exposed, the broken ingot is placed in a sealed container, and the air in the container is replaced with H ₂ gas. A rare earth metal characterized by supplying _H2 gas of 200 Torr to 50 Kg/ ^cm2 into the container to naturally disintegrate the fractured lumps, dehydrogenating the obtained naturally disintegrating alloy powder, and then further pulverizing it.・
This is a method for manufacturing boron-iron alloy powder for permanent magnets.

Function This invention was developed as a result of various studies on manufacturing methods that can efficiently and quickly obtain alloy powder for permanent magnets containing R, B, and Fe as main components. , the R-B-Fe alloy ingot for magnets has H ₂ occlusion property, and can spontaneously disintegrate in an H ₂ atmosphere to easily obtain coarsely pulverized powder of the R-B-Fe alloy for magnets. This is what we discovered.

The method for producing the alloy powder for magnets according to the present invention will be described in detail below. FIG. 1 is an explanatory diagram showing a closed container for H ₂ storage reaction used in the production method according to the present invention.

The ingot of this permanent magnet alloy can be obtained, for example, by high-frequency melting of electrolytic iron, ferroboron alloy, rare earth metal, or even electrolytic Co as a starting material, and then casting in a water-cooled copper mold, as shown in the examples. It will be done.

When the surface of this ingot is covered with an oxide film,
Since it is difficult for the H ₂ storage reaction to proceed, the metal surface is broken into blocks of a predetermined size, for example, and then H ₂ storage is performed.

For H ₂ storage, for example, a closed container shown in FIG. 1 is used. That is, a broken lump 3 that has been broken to a predetermined size is inserted into the raw material case 2, and the raw material is placed at a predetermined position in a container 1 which is equipped with an H ₂ gas supply pipe 4 and an exhaust pipe 5, and which can be sealed by tightening the lid. After charging case 2 and sealing it, exhaust while supplying H ₂ gas, and after sufficiently replacing the air in container 1, supply H ₂ gas at a pressure of 200 Torr to 50 Kg/cm ² and rupture it. Block 3 is allowed to absorb _H2 .

Since this H ₂ storage reaction is an exothermic reaction, a cooling pipe 6 for supplying cooling water is installed around the outer periphery of the container 1 to prevent a rise in temperature inside the container 1 while storing H ₂ at a predetermined pressure. By supplying gas for a certain period of time,
H ₂ gas is absorbed, and the fractured mass 3 spontaneously collapses into powder.

Furthermore, after cooling the powdered alloy, it is subjected to H ₂ gas removal treatment in a vacuum. Since the alloy powder treated as described above has fine cracks within its grains, it can be finely pulverized in a ball mill or the like in a short time to obtain an alloy powder with the required particle size of 1 μm to 80 μm.

In this invention, the air in the closed container may be replaced with H ₂ gas, or alternatively, the air may be replaced with inert gas in advance, and then the inert gas may be replaced with H ₂ gas.

In addition, the smaller the fracture size of the ingot, the lower the H ₂ crushing pressure, and the H ₂ gas pressure is
Broken ingots absorb H ₂ even under reduced pressure and are pulverized, but the higher the pressure is than atmospheric pressure, the more likely they are to be pulverized. However, if it is less than 200 Torr, the pulverizability becomes poor. Further, if it exceeds 50Kg/cm ² , it is preferable in terms of pulverization due to H ₂ absorption, but it is not preferable in terms of equipment and work safety, so it is set at 200 Torr to 50Kg/cm ² . From the viewpoint of mass production, the range is preferably 2 Kg/cm ² to 10 Kg/cm ² .

In this invention, the processing time for pulverization by H ₂ occlusion varies depending on the size of the sealed container, the size of the broken mass, and the H ₂ gas pressure, but is required to be 5 minutes or more.

Reason for composition limitation The reason for composition limitation of the ingot for rare earth-boron-iron permanent magnet alloy in the present invention will be explained below.

The rare earth element R contained in the ingot for permanent magnet alloy of this invention is a rare earth element that includes yttrium (Y) and includes light rare earths and heavy rare earths.

That is, R includes neodymium (Nd), praseodymium (Pr), lanthanum (La), cerium (Ce), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), and eurobium (Eu). , samarium (Sm), gadolinium (Gd), promethium (Pm), thulium (Tm), ytterbium (Yb), lutetium (Lu), and yttrium (Y).

As R, a light rare earth element is sufficient, especially Nd,
Pr is preferred. Also, it is usually sufficient to have one type of R, but in practice, a mixture of two or more types (Mitsushimetal, dididim, etc.) can be used for reasons such as convenience of availability, and Sm, Y, La, Ce, Gd , etc. can be used as a mixture with other R, especially Nd, Pr, etc. Note that this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within an industrially available range.

R is an essential element for alloy ingots for producing new R-B-Fe permanent magnets, and if it is less than 10 atomic %, high magnetic properties, especially high coercive force, cannot be obtained, and there is no H ₂ storage property. Because _H2 cannot be powdered, 30 atomic%
If it exceeds this, the residual magnetic flux density (Br) decreases, making it impossible to obtain a permanent magnet with excellent characteristics. By the way, R
is in the range of 10 atomic % to 30 atomic %.

B is an essential element for alloy ingots for manufacturing new R-B-Fe permanent magnets, and if it is less than 2 atomic %, a high coercive force (iHc) cannot be obtained and it does not have H ₂ storage properties. _H2 cannot be powdered, and if it exceeds 28 atomic percent, the residual magnetic flux density (Br) decreases, making it impossible to obtain an excellent permanent magnet. Therefore, B should be in the range of 2 atomic % to 28 atomic %.

Fe is an essential element for alloy ingots used to manufacture new R-B-Fe permanent magnets, but if it is less than 65 at%, the residual magnetic flux density (Br) decreases, and 82 at%
Since it is not possible to obtain a high coercive force if the Fe exceeds
Limited to 65 atom% to 82 atom%.

In addition, the reason why a part of Fe is replaced with Co is that it has the effect of improving the temperature characteristics of permanent magnets, but if Co exceeds 50% of Fe, high coercive force cannot be obtained, Permanent magnets cannot be obtained. Therefore, the upper limit of the substitution amount of Co is 50% of that of Fe.

In order to obtain an excellent permanent magnet having both high residual magnetic flux density and high coercive force in the alloy ingot of this invention, R10 atomic% to 25 atomic%, B4 atomic% to 26 atomic%, Fe68 atomic% to 80 atomic% are required. Atomic % is preferred.

Further, the alloy ingot according to the present invention has R, R,
In addition to Fe, the presence of unavoidable impurities in industrial production can be tolerated, but a portion of Fe or B can be replaced with 4.0 atom% or less of C, 3.5 atom% of P, 2.5 atom% or less of S, 3.5
By substituting at least one type of Cu in a total amount of 4.0 atomic % or less, it is possible to improve the manufacturability and lower the price of the magnet alloy.

Furthermore, in the R, B, Fe alloy or R, B, Fe alloy containing Co, Al of 9.5 atomic % or less, Ti of 4.5 atomic % or less, V of 9.5 atomic % or less, Cr of 8.5 atomic % or less, 8.0 Mn below 5 atomic %, Bi below 5 atomic %, Nb below 12.5 atomic %, Ta below 10.5 atomic %, Mo below 9.5 atomic %, W below 9.5 atomic %, Sb below 2.5 atomic %, 7 atoms By adding at least one of Ge at % or less, Sn at 3.5 atomic % or less, Zr at 5.5 atomic % or less, and Hf at 5.5 atomic % or less, it is possible to increase the coercive force of the permanent magnet alloy.

In the R-B-Fe permanent magnet of this invention,
It is essential that the main crystal phase be tetragonal, which is particularly effective in obtaining fine and uniform alloy powder and producing sintered permanent magnets with excellent magnetic properties.

According to this invention, powder with the required particle size of 35 mesh through the pulverization process can be obtained with good yield in a short time, and then the fine powder with the required particle size can be obtained through the pulverization process, but if the average particle size exceeds 80 μm, it is difficult to make a permanent magnet. Sometimes excellent magnetic properties, especially high coercive force, cannot be obtained, and if the average particle size is less than 1 μm, oxidation during the permanent magnet manufacturing process, that is, press forming, sintering, and aging treatment processes, is significant, making it difficult to obtain excellent magnetic properties. Therefore, the average particle size is set to 1 to 80 μm. Furthermore, to obtain excellent magnetic properties, alloy powders with an average particle size of 2 to 10 μm are most desirable.

Permanent Magnet Characteristics The R-B-Fe permanent magnet obtained using the alloy powder for permanent magnets according to the present invention has a coercive force iHc≧
1kOe, residual magnetic flux density Br > 4kG, maximum energy product (BH) max is equal to or higher than hard ferrite, and in the most preferable composition range,
(BH)max≧10MGOe, the maximum value is
Reach over 25MGOe.

Further, the composition of the alloy powder according to the present invention is R10
atomic% ~ 30 atomic%, B2 atomic% ~ 28 atomic%, Co45
When Fe is 65 atomic % to 82 atomic %, the resulting magnetically anisotropic permanent magnet alloy exhibits magnetic properties equivalent to those of the above magnet alloy, and the temperature coefficient of residual magnetic flux density is 0.1%/°C or less. , excellent properties can be obtained.

In addition, when the main component of R in the alloy powder is 50% or more of light rare earth metals, R12 at% to 20 at%, B4 at% to 24 at%, Fe65 at% to 28 at%, or Furthermore, it exhibits the best magnetic properties when containing 5 to 45 at% of Co.
Especially when the light rare earth metal is Nd, (BH)max
The maximum value reaches 33MGOe or more.

Furthermore, the alloy powder for permanent magnets according to the present invention is
Isotropic permanent magnets can be manufactured by pressure molding in the absence of a magnetic field.

Example Examples will be described below.

Example 1 As a starting material, electrolytic iron with a purity of 99.9%, B19.4
% and the remainder is impurities such as Fe and C. Nd with a purity of 99.7% or more is melted by high frequency, and then cast in a water-cooled copper mold to form a 15Nd-
1 kg of ingot having a composition of 8B-77Fe (at%) was obtained.

After breaking this ingot into pieces of 50 mm or less,
Insert 900g into the airtight container shown in Figure 1 above,
Flow _H2 gas for 10 min to replace air, 2.5
It was treated with _H2 gas pressure of Kg/ ^cm2 for 10 hours.

The coarse powder, which was naturally disintegrated by H ₂ absorption and then cooled, was subjected to dehydrogenation treatment in vacuum for 3 hours and coarsely ground to a throughput of 35 mesh. Next, 300 g of the coarsely ground powder was finely ground in a ball mill for 3 hours to obtain an alloy powder with an average particle size of 3.4 μm.

According to X-ray diffraction, the obtained alloy powder was an alloy powder whose main phase was a tetragonal intermetallic compound with a=12.45 Å and c=8.65 Å.

Using this alloy powder, it was oriented in a magnetic field of 10 kOe, pressure molded at 1.5 t/cm ² , and then heated at 1100°C for 1
A permanent magnet was produced by sintering the material under the conditions of 100 to 300 ml, followed by sintering in Ar and then allowing it to cool.

The magnetic properties of permanent magnets are Br＝12.2kG iHc=12.0kOe, (BH)max=34.2MGOe, Hc=10.9KOe.

For comparison, an ingot of the same composition was coarsely crushed to 20 mm or less, and then 300 g of coarse powder was crushed using a stamp mill.
The powder was ground for hours to obtain a coarsely ground powder with a mesh throughput of 35, and further finely ground for 6 hours using a ball mill to obtain an alloy powder with an average particle size of 3.65 μm.

This alloy powder obtained only by conventional mechanical crushing was made into a permanent magnet under the same manufacturing conditions, and the magnetic properties were measured. Br = 12.1kG iHc = 11.0kOe, (BH)max = 33.5MGOe, Hc = 10.7KOe I got it.

In other words, the production method according to the present invention, which is characterized by the pulverization of ingots by H ₂ absorption, achieves fine pulverization to a predetermined particle size in about half the time when comparing the same amount, compared to the conventional production method that only uses mechanical pulverization. It can be seen that powder can be obtained, the grinding time is shortened, and the grinding yield and grinding efficiency are improved.

Example 2 As a starting material, electrolytic iron with a purity of 99.9%, B19.4
% and the remainder is impurities such as Fe and C. Nd with a purity of 99.7% or more is melted by high frequency, and then cast in a water-cooled copper mold to produce an ingot with a composition of 15Nd1.5Dy8B75.5Fe (at%). 1
Got Kg.

After breaking this ingot into pieces of 50 mm or less,
Insert 900g into the airtight container shown in Figure 1 above,
Flow _H2 gas for 10 min to replace air, 10
It was treated with H ₂ gas pressure of Kg/cm ² for 1 hour.

The resulting coarse powder, which was naturally disintegrated by H ₂ absorption and cooled, was subjected to dehydrogenation treatment in vacuum for 2 hours and coarsely ground to a throughput of 35 mesh. Next, 300 g of the coarsely ground powder was finely ground in a ball mill for 3 hours to obtain an alloy powder with an average particle size of 3.3 μm.

According to X-ray diffraction, the obtained alloy powder was an alloy powder whose main phase was a tetragonal intermetallic compound with a=12.47 Å and c=8.65 Å.

Using this alloy powder, it was oriented in a magnetic field of 12 kOe, pressure molded at 1.6 t/cm ² , and then heated at 1120°C for 1
A permanent magnet was produced by sintering the material under the conditions of 100 to 300 ml, followed by sintering in Ar and then allowing it to cool.

The magnetic properties of permanent magnets are Br=11.5kG, iHc=18.5kOe, (BH)max=30.6MGOe, Hc was 10.8KOe.

For comparison, an ingot of the same composition was coarsely crushed to 20 mm or less, and then 300 g of coarse powder was crushed using a stamp mill.
The powder was ground for hours to obtain a coarsely ground powder with a mesh throughput of 35, and then finely ground for 6 hours using a ball mill to obtain an alloy powder with an average particle size of 37 μm.

This alloy powder obtained only by conventional mechanical grinding was made into a permanent magnet under the same manufacturing conditions, and its magnetic properties were measured. Br = 11.4kG, iHc = 18.4kOe, (BH)max = 30.0MGOe, Hc = 10.7 Got it in KOe.

In other words, the production method according to the present invention, which is characterized by the pulverization of ingots by H ₂ absorption, achieves a predetermined particle size in about 1/5 of the time when comparing the same amount, compared to the conventional production method that only uses mechanical pulverization. It can be seen that a finely pulverized powder can be obtained, and that the pulverization time is shortened and the pulverization yield and pulverization efficiency are improved.

Example 3 As a starting material, electrolytic iron with a purity of 99.9%, B19.4
% and the remainder is impurities such as Fe and C. A ferroboron alloy with a purity of 99.7% or more is melted by high frequency, and then cast in a water-cooled copper mold to produce 15Pr-8B.
1 kg of an ingot with a composition of -77Fe (at%) was obtained.

After breaking this ingot into pieces of 50 mm or less,
Insert 900g into the airtight container shown in Figure 1 above,
Inject _H2 gas for 10 minutes to replace air,
It was treated with H ₂ gas pressure of Kg/cm ² for 2 hours.

The coarse powder, which was naturally disintegrated by H ₂ absorption and then cooled, was subjected to dehydrogenation treatment in vacuum for 2 hours and coarsely ground to a throughput of 35 mesh. Next, 300 g of the coarsely ground powder was finely ground in a ball mill for 3 hours to obtain an alloy powder with an average particle size of 3.1 μm.

According to X-ray diffraction, the obtained alloy powder was an alloy powder whose main phase was a tetragonal intermetallic compound with a=12.50 Å and c=8.70 Å.

Using this alloy powder, it was oriented in a magnetic field of 11 kOe, pressure molded at 1.4 t/cm ² , and then heated at 1100°C for 1 hour.
A permanent magnet was produced by sintering the material under the conditions of 100 to 300 ml, followed by sintering in Ar and then allowing it to cool.

The magnetic properties of permanent magnets are Br=11.4kG, iHc=9.0kOe, (BH)max=26.9MGOe, Hc=8.3KOe.

For comparison, an ingot of the same composition was coarsely crushed to 20 mm or less, and then 300 g of coarse powder was crushed using a stamp mill.
The powder was ground for hours to obtain a coarsely ground powder with a mesh throughput of 35, and further finely ground for 6 hours using a ball mill to obtain an alloy powder with an average particle size of 3.4 μm.

This alloy powder obtained only by conventional mechanical grinding was made into a permanent magnet under the same manufacturing conditions, and its magnetic properties were measured. Br = 11.3kG, iHc = 8.8kOe, (BH)max = 26.5MGOe, Hc = 8.2 Got a KOe.

Effects of the Invention As is clear from the examples, the R-B- according to the present invention is characterized in that the ingot is powdered by H ₂ occlusion.
The manufacturing method of Fe-based alloy powder for permanent magnets can obtain finely ground powder with a predetermined particle size in about 1/4 of the time when comparing the same amount compared to the conventional manufacturing method that only involves mechanical pulverization. It can be seen that as the grinding time is shortened, the grinding yield and grinding efficiency are improved.

[Brief explanation of drawings]

Figure 1 is used in the manufacturing method according to the present invention.
FIG. 2 is an explanatory diagram showing a closed container for H ₂ storage reaction. 1... Container, 2... Raw material case, 3... Broken lump, 4... _H2 gas supply pipe, 5... Exhaust pipe, 6...
...Cooling piping.

Claims (1)

[Scope of Claims] 1 R (wherein R is at least one kind of rare earth elements including Y) 10 atomic % to 30 atomic %, B 2 atomic % to 28 atomic %, Fe 65 atomic % to 82 atomic % After breaking the component ingot so that the metal surface is exposed, the broken ingot is placed in a sealed container, and after replacing the air in the container with H ₂ gas, 200 Torr to 50 kg / cm ² of H ₂ gas is supplied to naturally disintegrate the fractured lumps, the obtained naturally disintegrated alloy powder is dehydrogenated, and then further finely pulverized.
A method for manufacturing boron/iron alloy powder for permanent magnets.