JPS61136656A - Production of sintered material for permanent magnet - Google Patents

Abstract

PURPOSE:To obtain a sintered material for a permanent magnet having improved oxidation resistance by sintering an Fe-Be-rare earth element type material for a permanent magnet by primary sintering to form a sintered body having a specified density, subjecting the sintered body to hot hydrostatic under specified conditions and aging it. CONSTITUTION:Alloy powder contg., by atom, 11-16% R (R is one or more kinds of rare earth elements including Y), 4-15% B and 70-35% Fe as principal components is molded in a magnetic field and sintered by primary sintering to form a sintered body having a density corresponding to >=90% of the theoretical density. The sintered body is subjected to hot hydrostatic pressing in a tightly sealed vessel at 700-1,100 deg.C under 500-1,300atm. with an inert gas as a pressure medium. The sintered body is then aged.

Description

Detailed Description of the Invention Field of Application The present invention relates to a method for producing a sintered permanent magnet material containing R (R is at least one of rare earth elements including Y), B, and Fe as main components. The present invention relates to a method of manufacturing a sintered permanent magnet material in which magnetic properties and mechanical strength are improved by increasing the density of the magnet material.

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

Due to the instability of the cobalt raw material situation in recent years, the demand for alnico magnets containing 20 to 35 W (%) of cobalt has decreased.
Inexpensive hard ferrite, whose main component is iron oxide, has come to dominate magnet materials.

On the other hand, rare earth cobalt magnets contain 50 to 60wt of cobalt.
%, and it is very expensive because it uses copper, which is not included in rare earth ores, but compared to other magnets,
Due to its extremely high magnetic properties, it has come to be used mainly in small, high-value-added magnetic circuits.

Therefore, the present inventor previously proposed a Fe-B-R-based permanent magnet (R is at least one rare earth element including Y) as a new high-performance permanent magnet that does not contain expensive Sm (patent application). No. 57-145072), furthermore,
In order to improve the temperature characteristics of a permanent magnet made of a magnetically anisotropic sintered body of the Fe-B-R system, by replacing a part of Fe with G, the Curie point of the resulting alloy is raised by one point, and the temperature characteristics are improved. We proposed a permanent magnet made of a Fe-Co B-R magneto-optical anisotropic sintered body with improved
No. 6663). These permanent magnets are excellent permanent magnets that use resource-rich light rare earths such as ceramics and circles as R, have Fs as a main component, and exhibit an extremely high energy product of 25 MGOs or more.

The rare earth metal that is the starting material for producing the above-mentioned new Fe-BR-based and Fa-CoBR-based permanent magnets is generally C
It is manufactured by a reduction method and electrolytic method, for example, by the following steps.

(2) As a starting material, the rare earth metal, electrolytic iron, ferroboron alloy, or further electrolytic 6 is melted at high frequency to cast a lump.

(2) Coarsely crush the ingot using a stamp mill, then wet crush it using a ball mill to obtain a fine powder of 1.51s to 10mm.

■Mold with orientation in a magnetic field.

■After sintering in vacuum, let it cool.

(2) Aging treatment in an At atmosphere.

The Fa-BR anisotropic permanent magnet material obtained by the above manufacturing method has a density of about 96% of the theoretical density,
Since it is a porous material, there is a limit to the improvement of magnetic and mechanical properties, and since this type of permanent magnet alloy contains a large amount of porcelain or yen, which is very easily oxidized, it is difficult to improve oxidation resistance in practical terms. Therefore, it is necessary to apply an oxidation-resistant coating such as a plating layer to the magnet surface. 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. .

Purpose of the Invention The present invention is directed to the production of a sintered permanent magnet material in which permanent magnet material is densified to improve magnetic properties and mechanical strength, and oxidation resistance is effectively improved through surface treatment in a subsequent process. Aimed at method.

Structure and Effects of the Invention As a result of various studies aimed at increasing the density of Fe-B-R permanent magnet alloys, the present invention has been made by first sintering a sintered body with a specific density, and then heating it under specific conditions. By isostatic pressing and aging, the density can be made almost 100% of the theoretical density, improving magnetic properties and mechanical properties, and by making the magnet material denser and non-porous. It was discovered that oxidation-resistant surface treatment functions effectively and is effective in improving oxidation resistance.

That is, the present invention provides R (where R is at least one kind of rare earth elements including Y) 11 atomic % to 16 atomic %, B
An alloy powder whose main components are 44 to 15 at% and Fe70 to 85 at%! l After forming at the lifting station, a sintered body having a density of 90% or more of the theoretical density is formed by primary sintering at, for example, 900°C to 1200°C in a vacuum, and this sintered body is treated with oxidation preventive material such as metallic titanium powder. In a sealed container embedded in the agent, the temperature was increased to 70°C using an inert gas as a pressure medium.
Hot isostatic pressing at 0°C to 1100°C and a pressure of 500 atm to 1300 atm to reduce the density to 98.5% of the theoretical density.
This is a method for producing a sintered permanent magnet material, which is characterized in that the above is followed by an aging treatment.

In this invention, the reasons for limiting the alloy powder for permanent magnets are as follows, and the density of the primary sintered body is set to 9 of the theoretical density.
The reason why it is set to 0% or more is because if it is less than 90%, the density cannot be made to be 98.5% or more of the theoretical density by hot isostatic pressing.

In addition, the temperature conditions in the hot isostatic pressing treatment were set to 700℃.
℃ to 1100℃ because if it is less than 700℃, it is impossible to increase the density even if hot isostatic pressure treatment is performed at high pressure.
This is because if the temperature exceeds 00°C, the temperature will be close to the melting point of the sintered body, and the deformation of the sintered body will be extremely undesirable. Roughly,
If the processing pressure is less than 500 atm, it is difficult to make the sintered body denser, and if it exceeds 1300 atm, it is possible to make the sintered body denser, but it is not preferable in terms of the durability and cost of the processing equipment. Atmospheric pressure to 1300 atm.

In this invention, the aging treatment conditions after the hot isostatic pressing treatment are such that the aging treatment temperature is 45°C in order to suppress excessive growth of crystal grains in the magnet body and develop excellent magnetic properties.
The temperature range is preferably from 0°C to 100°C, and the aging treatment time is preferably from 5 minutes to 40 hours.

The aging treatment time is closely related to the aging treatment temperature, but if it is less than 5 minutes, the aging treatment effect will be small and the magnetic properties of the obtained magnet material will vary widely, and if it exceeds 40 hours, it will take a long time for industrial purposes. Too impractical. The aging treatment time is from 30 minutes to 80 minutes from a practical standpoint and the desired development of magnetic properties.
time is preferable.

Moreover, multi-stage aging treatment of two or more stages can also be used for the aging treatment. For example, a sintered body sintered at 1060°C,
After hot isostatic pressing at a temperature of 900°C and a pressure of 900 atm, as the first stage, the
By performing an initial aging treatment for 0 minutes to 6 hours, and then performing at least one aging treatment at 450°C to 150°C for 2 to 30 hours, residual magnetic flux density, coercive force,
It is possible to obtain a magnetic material having extremely excellent magnetic properties in both squareness of the demagnetization curve.

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

Reason for limiting the alloy powder for permanent magnets The rare earth element iR used in the permanent magnet material of this invention is 11
Nd, pr, oy from atomic % to 16 atomic %.

At least one of Ho, Tb, or further,
La, Ce, Gd, Er, Eu,
Pi, Tm.

Those containing at least one of Yb and Y are preferred.

Further, one type of R is usually sufficient, but in practice, a mixture of two or more types (Mitsuhmetal, dididium, etc.) can be used for reasons such as convenience of availability.

Note that R does not need to be a pure rare earth element, and may contain impurities that are unavoidable in production within an industrially available range.

R (at least one rare earth element including Y) is an essential element in the alloy powder for manufacturing the new above-mentioned permanent magnet. Due to the cubic crystal structure, high magnetic properties, especially high coercive force, cannot be obtained, and if the content exceeds 16 at. permanent magnet cannot be obtained. Therefore,
The rare earth element is in the range of 11 atomic % to 16 atomic %.

B is an essential element in the above-mentioned novel alloy powder for permanent magnets, and when it is less than 4 at%, it becomes a rhombohedral structure,
A high coercive force (iHC') cannot be obtained, and if it exceeds 15 at%, the B-rich non-magnetic phase increases and the residual magnetic flux density (iHC') increases.
Br) decreases, making it impossible to obtain an excellent permanent magnet. Therefore, B is in the range of 4 atomic % to 15 atomic %.

Fe is an essential element in the above-mentioned new alloy powder for permanent magnets, and if it is less than 70 atomic %, the residual magnetic flux density (B
) decreases and exceeds 85 at %, a high coercive force cannot be obtained, so Fe is contained in an amount of 70 at % to 85 at %.

In addition, in the alloy for permanent magnets according to the present invention, replacing a part of Fe with 6 can improve the temperature characteristics without impairing the magnetic properties of the resulting magnet.
If the amount of o substitution exceeds 50% of F, the magnetic properties will deteriorate, which is not preferable.

In order to obtain high residual magnetic flux density and high coercive force in the alloy powder of this invention, R12 to 15 atom%, B6
Preferably, the content is 6 to 14 at%, and Fe7171 is preferably 82 at%.

Further, the alloy powder for permanent magnets according to the present invention has R, B,
In addition to Fe, the presence of unavoidable impurities in industrial production can be tolerated, but a portion of B may be 4.0 atomic % or less of C13, 5 atomic % or less of P, 2.5 atomic % or less of S, 3. At least one type of Cu of 5 at% or less, 4.0 at% in total amount
By substituting with the following, 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 is added to Fe-based or R-B-Co-Fe-based permanent magnets because it is effective in improving the coercive force, etc., improving manufacturability, and reducing costs. However, addition to improve coercive force causes a decrease in residual magnetic flux density (Sr), so it is desirable to add in the following range.

At less than 5.0 atom%, T less than 3.0 atom% (,5
, 5 atomic % or less of V, 4.5 atomic % or less of Or.

Mn of 5.0 atom% or less, 81.9.0 of 5 atom% or less
Nb at % or less, Ta at 7.0 atomic% or less, 5.2
Mo2S below atomic %, W below 0 atomic %, 3i) below 1.0 atomic %, GOll below 3 J atomic %, 5 atomic %
The following 3n, 3.3 atomic % or less of Zr.

N1 of 6.0 atom% or less; 81.3 of 5.0 atom% or less
．． At least one type of Ht of 3 atomic % or less is added and contained. However, if two or more types are contained, the maximum content m is 3 atomic % or less of the added element having the maximum value. It becomes possible to increase the coercive force of the magnetic G.

The main phase of the alloy powder in this invention is a square shape with at least 50 vol% or more, and a nonmagnetic intermetallic compound with at least 1 vol% or more, to produce a sintered permanent magnet having excellent magnetic properties. is essential.

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

The magnetically anisotropic permanent magnet material according to the present invention exhibits a residual magnetic flux density 3r > 10.5 KG, and has a maximum energy product (
B t(> max≧25M G Os @indication L/,
[Large 1111 Reach 40 MGOe or more.

Further, the composition of the alloy powder for permanent magnets of the present invention is R11 atomic % to 16 atomic %, B44 atomic % to 15 atomic %, Co45
At % or less, the remainder being Fa, the resulting magnetically anisotropic permanent magnet alloy exhibits magnetic properties equivalent to those of the above magnet alloy, and has an excellent temperature coefficient of residual magnetic flux density of 0.1%/°C or less. characteristics are obtained.

In addition, when the main component of R in the alloy powder for permanent magnets of the present invention is light rare earth metals accounting for 50% or more, R12 to 15 at%, B 6 to 14 at%, Fe
In the case of 71 at% to 82 at%, or roughly Co5
When the main component is from atomic% to 45 atomic%, in the case of a sintered magnet, the layer also exhibits excellent magnetic properties, and especially when the light rare earth metal is ceramic, the maximum value of (BH)max is 40MG.
Reaching Oe or more.

EXAMPLE An alloy powder having a composition of 79Fa7B14Nd and an average particle size of 4 mm in terms of atomic percentage was heated to 2 mm in a magnetic field of 10 koe.
After pressure molding with tone pressure, lX1O-7T
A primary sintered body having a density of 96% of the theoretical density was obtained by sintering for 2 hours at 1 oso ℃ in a vacuum of Hot isostatic press treatment was performed at a temperature of 900° C. and a pressure of 900 atm using gas as a pressure medium.

Then, after performing an aging treatment at 600° C. for 1 hour, the magnetic properties and mechanical properties were measured. The results are shown in Table 1.

In addition, for comparison, a comparative magnet material was manufactured using the above manufacturing method except that the primary sintered body was not subjected to hot isostatic pressing treatment, and its magnetic properties and mechanical properties were similarly measured. The results are shown below.

Tomonao 2 Atomic percentage: 71.5Fe 8B 6Co14.5J
An alloy powder with an average particle size of 5p and having a composition of 10k
After pressure molding at a pressure of 2 johns in a magnetic field of Oe, it was molded at 1040°C in a vacuum of 1 x 1 O-4 Torr at 2
A primary sintered body having a density of 95% of the theoretical density was obtained by sintering for a period of time, and this primary sintered body was embedded in metal titanium powder in a sealed container at a temperature of 800°C using Ar gas as a pressure medium. .

It was subjected to hot water storage pressure breathing treatment at a pressure of 900 atm.

Then, after performing an aging treatment at 600° C. for 1 hour, the magnetic properties and mechanical properties were measured. The results are shown in Table 2.

In addition, for comparison, a comparative magnet material was manufactured using the above manufacturing method except that the primary sintered body was not subjected to hot isostatic pressing treatment, and its magnetic properties and mechanical properties were similarly measured. The results are shown in the table.

As is clear from the results shown in Tables 1 and 2 below, 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.

Applicant: Sumitomo Special Metals Co., Ltd. Voluntary procedure February 18, 1985

Claims (1)

[Claims] 1R (where R is at least one rare earth element including Y)
Species) 11 atom% to 16 atom%, B4 atom% to 15 atom%
, an alloy powder whose main component is 70 at% to 85 at% Fe is formed into a sintered body having a density of 90% or more of the theoretical density by primary sintering after magnetic field forming, and this sintered body is placed in a sealed container. , using an inert gas as a pressure medium, at a temperature of 700°C to 11°C.
A method for producing a sintered permanent magnet material, which comprises subjecting the material to hot isostatic pressing at 00°C and a pressure of 500 to 1300 atmospheres, followed by aging treatment.