JPS6217149A - Manufacture of sintered permanent magnet material - Google Patents

Abstract

PURPOSE:To manufacture a high-density sintered permanent magnet material by subjecting an alloy powder composed essentially of rare earth elements, B and Fe reach having a specific composition to compacting in a magnetic field, primary sintering and then hot hydraulic pressing treatment under proper conditions. CONSTITUTION:The alloy powder composed essentially of by atom, 10-30% R (where R consists of at least one element among Nd, Pr, Dy, Ho and Tb or further consists of at least one element among La, Ce, Sm, Cd, Er, Eu, Tm, Yb, Lu and Y), 2-28% B and 65-80% Fe is compacted in a magnetic field. Subsequently, the resulting green compact is subjected to primary sintering to be formed into a sintered compact having a density of >=90% of theoretical density. This sintered compact is further age-treated at 700-1,000 deg.C, as necessary, and then subjected to hot hydraulic pressing treatment in a hermetically sealed vessel by the use of an inert gas as a pressure medium, at 400-700 deg.C under the pressure of 500-1,300atm. In this way, the sintered permanent magnet material is made high-density, so that magnetic properties and mechanical strengths can be improved and, by the succeeding surface treatment stage, oxidation resistance can be effectively improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application This invention relates to a sintered permanent la'E material mainly composed of R (R is at least one rare earth element including Y), B, and Fe.
The present invention relates to a method for manufacturing J material, and in particular to a method for manufacturing sintered permanent FB5 material in which permanent magnet material is densified by hot isostatic pressing to improve magnetic properties and mechanical strength.

BACKGROUND ART Current typical permanent magnet materials are alnico, hard ferrite and rare earth cobalt magnets.

Among these, rare earth cobalt magnets have extremely excellent magnetic properties and are used for a variety of purposes, but their main components, SNd and Cot, are both in short supply and expensive. , it is difficult to stably supply it in large quantities. Therefore, there has been a strong desire for a permanent magnet material that has excellent magnetic properties, is inexpensive, and is composed of constituent elements that are abundant in resources and can be stably supplied in the future.

The present applicant previously proposed a Fe-BR-based permanent magnet (R is at least one of rare earth elements including Y) as a new high-performance permanent magnet that does not contain expensive Sm (Japanese Patent Application Laid-Open No. 59-1991). -46008, JP-A-59-64733,
JP-A-59-89401, JP-A-59-132104
issue).

This permanent magnet uses resource-rich light rare earths such as ceramics and circles as R, and has 25MGO as the main component.
It is an excellent permanent VI1 stone that shows an extremely high energy product of 8 or more.

Such Fa-B-R based anisotropic permanent magnet material has a density of about 96% of the theoretical density and is a porous material, so there is a limit to the improvement of magnetic properties and mechanical properties. Permanent magnet alloys contain a large amount of Nd or Nd, which is highly oxidizable, so in practice, Ia is used to improve oxidation resistance.
It is necessary to apply an oxidation-resistant coating such as a plating layer on the surface of the stone garment. However, as mentioned above, this type of magnet is a porous material, and there have been problems such as moisture or acidic or alkaline solutions for surface treatment remaining in the micropores, which can cause rust over time. .

For this reason, the inventor first densified the Fa BR permanent magnet material by hot isostatic pressing,
We have proposed a manufacturing method for sintered permanent magnet materials (Japanese Patent Application No. 59-259761@) that aims to improve magnetic properties and mechanical strength, and improves oxidation resistance through surface treatment in subsequent steps.

However, in the above ':''!')Q method, Fe-
Depending on the composition of the BRR permanent magnet material, particularly the composition of R, there is a problem in that even if hot isostatic pressing is performed, the sintered body cannot be densified.

Purpose of the Invention The present invention is directed to the production of a sintered permanent magnet material that improves magnetic properties and mechanical strength by increasing the quality of permanent Ia5ia stone material, and improves oxidation resistance through surface treatment in subsequent steps. A method for producing a sintered permanent magnet material, in particular, in which a sintered magnet body can be densified by hot isostatic pressing, regardless of the R composition of the Fe-B-R permanent magnet material. Aimed at method.

Structure and Effects of the Invention As a result of various studies aimed at increasing the density of Fe-BRR permanent magnet materials, the present invention has been made into a sintered body having a specific density through primary sintering, and then subjected to hot isostatic pressure under specific conditions. By pressing and aging, the density is almost 1 of the theoretical density.
00%, improved magnetic properties and improved mechanical properties can be obtained, and by making the magnet material dense and non-porous, the oxidation-resistant surface treatment functions effectively and is effective in improving oxidation resistance. However, in addition, in a composition in which a large amount of Rr i ch liquid phase appears during hot isostatic pressing, pores are generated inside the sintered body without hot isostatic pressing. We found that a decrease in density occurs, and that when hot isostatic pressing is performed at a lower temperature than the hot isostatic pressing under the specific conditions mentioned above, it is possible to obtain a composition with a large amount of rich liquid phase. However, it was found that the sintered body could be uniformly subjected to hot isostatic pressing, and a high density of almost 100% of the theoretical density could be achieved.

That is, in this invention, R10 atomic % to 30 atomic %, (R is Nd, Pr, D
y, )to.

At least one of Tb or in addition La, Co
.

SNd, Ca, Er, EDy, Ding Nd, Yb,
An alloy powder whose main components are B2 at % to 28 at % and Fe65 at % to 80 at % (consisting of at least one of La and Y) is formed into a powder with a theoretical density of 90% or more by primary sintering after magnetic field molding. The sintered body has a density, and if necessary, the sintered body is
After aging at a temperature of 400°C to 1000°C, inert gas is used as a pressure medium in a sealed container embedded in an antioxidant such as metallic titanium powder (temperature 400°C to 700°C), pressure 5
This is a method for producing a sintered permanent magnet material, which is characterized by subjecting the material to hot isostatic pressing at a pressure of 00 to 1300 atmospheres, and subjecting it to an aging treatment if necessary.

In this invention, the reasons for limiting the alloy powder for permanent magnets are as described below.The density of the primary sintered body is set to be 90% or more of the theoretical density. This is because the density cannot be made 98.5% or more of the theoretical density.

In addition, the temperature conditions in the hot isostatic pressing treatment were set to 400℃.
°C to 700 °C is because at temperatures below 400'C, high-pressure hot isostatic pressure treatment cannot increase the density.
When the temperature exceeds 700℃, a rich liquid phase is formed.
Depending on the composition, hot isostatic pressing may not be applied, which is not preferable.

Furthermore, if the processing pressure is less than 500 atm, it is difficult to increase the density of the sintered compact, and if the processing pressure exceeds 1300 atm, it is possible to increase the density, but this is not desirable in terms of the durability and cost of the processing equipment. , 500 atm to 1300 atm.

In this invention, as a pre-process performed before hot isostatic pressing, necessary steps are taken to improve the residual magnetic flux density, coercive force, and squareness of the demagnetization curve of the magnet after hot isostatic pressing. Accordingly, aging treatment is performed at a treatment temperature of 700'.
If the temperature is less than C, the coercive force will decrease, and if it exceeds 1000℃, the coercive force will also decrease, so the aging treatment temperature should be 700℃.
The range of C to 1000'C is preferable, and the aging treatment time is preferably 30 minutes to 6 hours. If the aging treatment is carried out for less than 30 minutes, the effect of the aging treatment will be small and variations in the magnetic properties of the magnet material subjected to 1q will become large, and if it exceeds 6 hours, the effect will be saturated and it is not practical.

In this invention, in order to improve the coercive force and the squareness of the demagnetization curve, aging treatment may be performed after hot isostatic pressing, and the aging treatment temperature is in the range of 450'C to 700'C. is preferable, and the aging treatment time is preferably 5 minutes to 40 hours. If it is less than 5 minutes, the effect of the aging treatment will be small and the magnetic properties of the obtained magnet material will vary widely, and if it exceeds 40 hours, it will take an industrially too long time to be practical.

From the viewpoint of desirable development of magnetic properties and practical aspects, the aging treatment time is preferably 30 minutes to 8 hours. Moreover, multi-stage aging treatment of two or more stages can also be used for the aging treatment.

In addition, instead of multi-stage aging treatment, cooling from the aging treatment temperature of 450°C to 700°C to air temperature is performed using a cooling method such as air cooling or water cooling at a cooling rate of 0.2°C/min to 20°C/min. By this method, it is also possible to obtain a permanent fj1'EJ material having magnetic properties equivalent to those obtained by the above-mentioned aging treatment.

Reasons for limiting the alloy powder for permanent magnets The rare earth element R in the rare earth alloy powder of the present invention accounts for 12 at % to 20 at % of the composition, and Nd, Pr.

At least one of Dy, Ho, Tb, or further, La, Ce, SNd, Gd, Er,
Contains at least one of EDy, TNd, Yb, La, and Y.

Also, normally one type of R is sufficient, but in practice two types are sufficient.
A mixture of more than one species (Mitushmetal, Didim, etc.) can be used for reasons such as availability.

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 in the new Fe-B-R permanent magnet, and if it is less than 10 atomic %, the crystal structure becomes cubic, which is the same structure as α-iron, so it has high magnetic properties, especially If a high coercive force cannot be obtained and the content exceeds 30 at%, the R-rich nonmagnetic phase increases, and although the coercive force is 10 koa or more, the residual magnetic flux density 3r decreases, making it impossible to create a permanent magnet with excellent characteristics. I can't get it.

Therefore, the rare earth element is in the range of 10 atomic % to 30 atomic %.

B is an essential element in Fa-BR permanent magnets, and if it is less than 2 atomic %, the rhombohedral crystal structure becomes the main phase, and a high coercive force of 1l-1c cannot be obtained, and the coercive force is less than 10 k08, which is 28 atoms. %, the 8-rich nonmagnetic phase increases, the residual magnetic flux density B' decreases, and (B H) maX
It becomes less than 20HGOe, and no permanent Wi stone can be obtained. Therefore, B is in the range of 2 atomic % to 28 atomic %.

Fe is an essential element in the new above-mentioned permanent magnet, and (if it is less than 35 atomic %, the residual magnetic flux density Br decreases,
If it exceeds 80 atom%, high coercive force cannot be obtained.
The content of Fe is 65 atomic % to 80 atomic %.

In addition, in the permanent magnet material according to the present invention, replacing a part of Fe with CO can improve the temperature characteristics without impairing the magnetic properties of the resulting magnet.
If the amount of substitution exceeds 30% of Fe, the magnetic properties will deteriorate, which is undesirable, and the preferable amount of substitution is 20% or less.

In addition to R, B, and Fe, the permanent magnet according to the present invention also includes
Although the presence of unavoidable impurities in industrial production can be tolerated, B
A part of C is 4.0 atomic% or less, P is 3.5 atomic% or less
, at least one of the following: 2.5 atomic % or less S, 1.5 atomic % or less 5, 5 atomic % or less SL, the total amount is 5.0
By substituting at atomic % or less, it is possible to improve the manufacturability and reduce the cost of permanent magnets.

In addition, at least one of the following additional elements is RB
It can be added to Fe-based permanent magnets because it is effective in improving the coercive force and squareness of the demagnetization curve, improving manufacturability, and reducing costs. However, addition to improve coercive force causes a decrease in residual magnetic flux density (Br), so it is desirable to add in a range that is equal to or higher than the residual magnetic flux density of conventional hard ferrite magnets.

5.0 at% or less Ti, 1.3.0 at% or less Ti, 5
．． 5 at% or less V, 4.5 at% or less cr15
．． Hn of 0 atomic % or less, Bi of 5.0 atomic % or less, 9.
Nb of 0 atomic% or less, Ta of 7.0 atomic% or less, 5.2
No less than 5.0 atom%, 1.0 less than 5.0 atom%
Sb below 3.5 atomic %, Ge below 3.5 atomic %.

Button of 1.5 atomic % or less, l'' of 3.3 atomic % or less, 6.
Ni of 0 atomic % or less, Zn of 1.1 atomic % or less.

3.3 atomic % or less of Hf.

At least one of these elements is added and contained; however, when two or more types are contained, the maximum content is less than or equal to the atomic percent of the element having the maximum value among the added elements.
It becomes possible to increase the coercive force of permanent magnets. Particularly preferable additive elements are V and Nb.

D, No, I, Cr, M, the content is preferably a small amount, 3 atomic % or less is effective, and 〃 is 0.
The amount is 1 to 3 at%, preferably 0.2 to 2 at%.

It is essential that the main crystalline phase (80% or more of a specific phase) be tetragonal in order to exhibit high magnetic properties as a magnet. This magnetic phase is composed of FeBR tetragonal compound crystals, and the grain boundaries are surrounded by a non-magnetic phase. The nonmagnetic phase mainly consists of an R-rich phase, and if there is a large amount of B, a B-rich phase may also be partially present. The existence of non-magnetic phase grain boundary regions is thought to contribute to high coercive force, and is an important structural feature of the alloy of the present invention, and even a small amount of solder is effective; for example, IVOI% or more is sufficient It's the amount.

Further, the permanent magnet of the present invention can be press-molded in a magnetic field to obtain a magnetically anisotropic magnet, and can be press-molded in a non-magnetic field to obtain a magnetically isotropic magnet.

In the raw material powder, TLB2, BN, ZrB2, ZrB
rz, HfBz, VB2, NbB, NbB2, Ta
B, TaB2, CrB2, MoB, MOB2, MO
By containing at least one of borides such as 2BSW B and W2 B in an amount of 0.05 atomic % to 3.0 atomic %, growth of compact grains during sintering of the magnet body can be suppressed. 1' The permanent magnet according to the present invention has a coercive force iHc≧10k:Qa
, the residual magnetic flux density Br>9kG, and the maximum energy
: Lugie M(BH)max is [(8N)max≧] in the most preferable composition range.
It shows 258 GOe, and the maximum value is 508 GOa or more.
Reach 1.

,. 1. . EIIJI&a Yu5yo. □Ka. F3,
1゜R11 atomic% to 16 atomic%, B22 atomic% to 15 atomic%, i'Co45 atomic% or less, Fa
In the case of the remainder, the obtained magnetically anisotropic permanent magnet alloy exhibits magnetic properties equivalent to those of the above-mentioned magnet alloy, and has a temperature coefficient of residual magnetic flux density of 0.1%/° C. or less, resulting in excellent properties.

In addition, in the case where the main component of R in the alloy powder for permanent magnets of this invention is 50% or more of the light rare earth metal mainly composed of dynamic and circular metals, R12 at % to 15 at %, B5.5 @ child % to
When the main component is 10 atomic % with the remainder being Fs, or when a part of Fθ is further replaced with 20% or less of 6, sintered Ia5 exhibits excellent magnetic properties, especially when light rare earth metals are used. In the case of ceramic, the maximum value reaches 508 GOθ or more.

Example average particle size 4ρ consisting of the composition shown in Table 1 in atomic percentage
After pressure molding the alloy powders (uninvention positive 1 to 4) at a pressure of 2 tons in a magnetic field of 10 kOθ,
A primary sintered body having a density of 96% of the theoretical density was obtained by sintering at 1060°C for 2 hours in a vacuum of -7 orr, and this primary sintered body was embedded in metallic titanium powder in a sealed container. Enter,
Using Ar gas as pressure medium, temperature 600℃, pressure 900℃
Hot isostatic pressing at atmospheric pressure.

Then, after performing an aging treatment at 660° C. for 1 hour, the magnetic properties and mechanical properties were measured. The results are shown in Table 2.

For comparison, the temperature of the primary sintered body was 800°C.

Hot isostatic pressing at a pressure of 900 atm and 600°C.

Comparative magnet materials (Nos. 5 to 8) were produced using the above production method except that they were subjected to an aging treatment for 1 hour, and their magnetic properties and mechanical properties were similarly measured, and the results are shown in Table 2.

As is clear from the results in Tables 1 and 2, it can be seen that the permanent magnet material manufactured by the manufacturing method of the present invention has improved magnetic properties and mechanical properties.

Below margin

Claims (1)

[Claims] 10 at % to 30 at % of R, (R is at least one of Nd, Pr, Dy, Ho, Tb, or furthermore, La, Ce, Sm, Gd, Er,
An alloy powder containing at least one of Eu, Tm, Yb, La, and Y) B2 to 28 atom% and Fe65 to 80 atom% is formed by magnetic field molding and then primary sintering. A sintered body having a density of 90% or more of the density is formed, and this sintered body is placed in a sealed container,
Temperature: 400°C to 700°C using inert gas as pressure medium
) A method for producing a sintered permanent magnet material, which comprises performing hot isostatic pressing at a pressure of 500 atm to 1300 atm. R 10 atomic % to 30 atomic %, (R is at least one of Nd, Pr, Dy, Ho, Tb, or in addition, La, Ca, Sm, Cd, Er,
An alloy powder containing at least one of Eu, Tm, Yb, La, and Y) B2 to 28 atom% and Fe65 to 80 atom% is formed by magnetic field molding and then primary sintering. The sintered body is made into a sintered body having a density of 90% or more, and the sintered body is further heated at 700°C to 1
After aging at 000°C, the temperature is 400°C to 700°C and the pressure is 50°C using an inert gas as a pressure medium in a sealed container.
A method for producing a sintered permanent magnet material, the method comprising performing hot isostatic pressing at 0 atm to 1300 atm.