JPS58193336A - Permanent magnet material - Google Patents

Abstract

PURPOSE:To enhance the magnetic characteristics of an obtained permanent magnet material, in a rare earth cobalt type magnet, by respectively adjusting oxygen content and carbon content to a specific amount or less. CONSTITUTION:The oxygen content and the carbon content in an RCo type magnet containing, on the basis of a wt., 20-30% R (wherein R is one kind or more rare earth element of Y, Ce, Sm, Sr and a misch metal) and the remainder Co and one kind or more transition metal element of Fe, Ni or Cu replacing the part of Co are adjusted as mentioned hereinbelow. That is, the oxygen content in the above mentioned magnet is adjusted to 0.25% or less, the carbon content therein to 0.05% or less and the total sum of oxygen and carbon amounts to 0.25% or less. Or, according to necessity, the part of the above mentioned transition metal element is further replaced with one kind or more elements from among Mu, V, Ti, Nb, Zr, Ta and Hf.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rare earth cobalt permanent magnet containing a rare earth metal such as yttrium, cerium, samarium, praseodymium, or a mixture thereof (mitsch metal).

Demand for rare earth cobalt magnets has increased rapidly in recent years as an excellent permanent magnet material that has a higher coercive force and a larger energy product than the alnico magnets and ferrite magnets that are mass-produced today. It is widely used in a wide range of fields, mainly in the industrial world.

The rare earth cobalt alloys are melted using metal raw materials with few impurities and in an argon atmosphere to prevent oxidation. In the pulverization process, a pulverizer such as a ball mill or a vibrating mill is used to finely pulverize the alloy, which is easily oxidized like this alloy. It is carried out by the grinding method. organic tgt
The fine powder from which jX has been removed has a shape close to the prescribed product shape.

It is molded in a mold while applying a magnetic field, and a binder such as paraffin, camphor, or stearic acid is usually added before pressing to prevent the molded product from slipping or cracking. After that, a debinding treatment is performed in a vacuum to remove the binder mentioned above, followed by a sintering and aging treatment process in a non-oxidizing atmosphere in an oxidation prevention tank to create a permanent magnet with the desired magnetic properties. Get the materials.

On the other hand, rare earth metals, which are one of the main components of rare earth cobalt-based magnets, have a strong affinity with oxygen and are effective as deoxidizers in continuous hammer steelmaking, including Mg, ~A6. Since Si and other Si are also strong,
Easily forms oxides. It also has an affinity for carbon and easily combines with rare earth elements to form carbides.

In addition, the magnetic properties of this permanent magnet include finely pulverized particle size, sintered
It is greatly affected by alloy composition based on process factors such as aging treatment conditions.

Therefore, the inventors of the present application focused on the behavior of oxygen and carbon elements in rare earth cobalt magnet alloys, and
We conducted a detailed study on the effect of carbon content on magnetic properties, and found that magnets with excellent magnetic properties have a slight amount of oxides and
Although carbides exist at grain boundaries, oxides and carbides with rare earth elements that exist inside the crystal grains that make up rare earth cobalt magnets have a very large effect on the magnetic properties of water-based magnet alloys. The present invention was completed based on the discovery that characteristic deterioration occurs.

In other words, as mentioned above, this alloy is extremely active, which is a unique property not found in other magnet materials, so it is susceptible to oxidation in the magnet manufacturing process and residual organic solvents during pulverization and binder for press molding. Carbon etc. caused by
It has been discovered that rare earth oxides and carbides that remain within crystal grains have a very harmful effect on magnetic properties and are a significant cause of deterioration of magnetic properties.
11 The permanent magnet material of the present invention has a composition of R (R is yttrium, cerium, and samarium) in terms of weight ratio.

20-30% of one or more rare earth elements (including praseodymium, 7 metals), the balance being Co and C
In a rare earth cobalt magnet in which o is partially replaced with one or more transition metal elements such as Fe, Ni, or Cu, 5 oxygen content is 0.25% or less, carbon content is 0.05% or less, and oxygen and carbon content is It is a permanent magnet material characterized in that the total sum of
, Ta, and Hf are substituted with one or more elements.

Here, the reason why the oxygen and carbon contained in the rare earth cobalt magnet alloy deteriorate the magnetic properties is considered as follows.

In other words, after the final heat treatment process, the acids and carbon contained during the magnet manufacturing process form rare earth oxides and carbides and remain in the magnet as impurities. When it comes to exist inside the crystal grains, it becomes a nucleus when a reverse magnetic domain is generated and significantly reduces the coercive force. In addition, the presence of undesirable oxide/carbide impurities as essential constituents of magnetic properties also causes a decrease in the saturation magnetic flux density, which leads to a decrease in the residual magnetic flux density and the maximum magnetic energy product. This is thought to cause overall deterioration of characteristics.

In the rare earth cobalt magnet of the present invention, the oxygen content is 0.
The reason why the carbon content was limited to 25% or less, the carbon content was limited to 0.05% or less, and the total amount of oxygen and carbon was limited to 0.25% or less is as follows.

In other words, it is originally desirable to not contain any of these elements at all in terms of improving magnetic properties, but as mentioned above, their inclusion in the product as a permanent magnet material is unavoidable due to the magnet manufacturing process of this alloy. .

First, the reason for limiting the oxygen content to 0.25% or less is
If oxygen is contained in excess of this amount, the rare earth cobalt magnet will contain more than approximately 2% of rare earth oxides not only at the grain boundaries but also within the grains, resulting in a significant decrease in coercive force. This is because the residual magnetic flux density decreases, resulting in a significant decrease in the maximum magnetic energy product, which is important as a permanent magnet material.

Also, the reason why the carbon content is limited to 0.05% or less is that if carbon exceeds this content, rare earth carbides exceeding about 0.4 cm in rare earth cobalt magnets will be added to the grain boundaries and crystallization will occur. This is because it is contained even within the grains, so the residual magnetic flux density does not decrease much, but the coercive force is extremely small, and the maximum magnetoelectric energy product is also small, making it impossible to use as a practical permanent magnet material. be. As mentioned above, the amount of oxygen and carbon each causes a specific deterioration of magnetic properties. Since this causes a significant decrease in coercive force and accompanying deterioration of magnetic properties, the total amount of oxygen and carbon is also set to 0.25% or less.

Hereinafter, the present invention will be explained in detail with reference to Examples.

(Example 1) Sm with a purity of 99.9%: 26.7 wt%, and Co with a purity of 99.9%: 47.7 wt%, Fe i
122wt%, Nii 5.5wt%.

An alloy consisting of 7.9 wt% Cu i was prepared by arc button melting, and after coarsely pulverizing this button-shaped molten alloy, it was heated with 120 CC of organic solvent and 500 Ji of stainless steel poles.
Finely ground with 'r in a ball mill, average particle size 4μm
It was made into powder.

Next, after sufficiently removing the solvent from this powder in a high vacuum of 10 TorrO, it was press-molded together with a binder in a magnetic field of 1 OKOe to produce a compression-molded body.

This compressed body was subjected to debinding treatment in vacuum at 150°C for 3 hours, sintered at 1200°C for 2 hours in an argon atmosphere with a purity of 99.99999, and then aged at 5800°C for 4 hours.

The thus prepared sample (Sample A) was measured for magnetic properties and analyzed for oxygen and carbon content. The results were as shown in Table 1.

In addition, a fine powder prepared in the same manner as Sample A was pulverized in an argon gas stream, and after removing the solvent, 10K
A binder was added and press molded in a magnetic field of Oe to produce a compression molded body. This compressed body is debindered in vacuum at 150°C for 2 hours. After ;1200°CX
After sintering in an argon atmosphere with a purity of 999% for 2 hours, aging treatment was performed at 800° C. for 4 hours. The magnetic properties of the comparative sample (sample B) thus prepared were measured, and the oxygen and carbon contents were analyzed. The results are also shown in Table 1.

As is clear from the results, sample B has an oxygen content of 0.2
Since it exceeds 5%, the magnetic properties are deteriorated.

(Example 2) Sm with a purity of 99.9%; 25.8 wt% and C□ with a purity of 99.9%; 57.6 wt%, Fe;
7. An alloy consisting of Cu i 9.6 wt% and Cu i 9.6 wt% was prepared by arc button melting, and this button-shaped molten alloy was coarsely pulverized and then finely pulverized with an organic solvent 120CG and stainless steel pole '5'00gIr. It was made into a powder with a particle size of 3 μm.

Next, after removing the solvent from this powder in a high vacuum of 10 TorrO, 1.0 wt % of camphor was added and press molding was performed. This compressed body was heated at 150°C x 3 hours at 2°C.
Time aging treatment was applied. Samples prepared in this way (
Sample C) was measured for magnetic properties and analyzed for oxygen and carbon content. The results were as shown in Table 1.

Also, a compressed body made in the same manner as sample C.

After debinding treatment in vacuum at 150°C for 2 hours, 11
Sintering was performed at 90° C. for 2 hours in an argon atmosphere with a purity of 99.99 m, followed by aging treatment at 800° C. for 2 hours. The comparative samples thus obtained were analyzed for magnetic properties and oxygen and carbon content, and the results are shown in Table 1.

The sample sample has an oxygen content and a carbon content of 0.25wt each.
%, even if it is less than 0.05wt%, the total is 0.2
It can be seen that since the content exceeds 5 wt%, the magnetic properties are significantly deteriorated.

(Example 3) S mi 25.8 wt% with a purity of 99°9% and C i 49.8 wt% with a purity of 99.9%, Fe
i 14.8wt%, Cu: 7.9wt%, Mni
An alloy consisting of 0.8 wt% Zl i and 0.9 wt% Zl i was melted in an arc button, and after coarsely pulverizing the melted alloy, it was heated with 120 CC of organic solvent and 500 yr of stainless steel pole.
The mixture was pulverized in a ball mill to obtain a powder with an average particle size of 4.5 μm or 1 μm. Next, after sufficiently removing the solvent from this powder in a high vacuum of 10 TorrO, it was press-molded together with a binder in a magnetic field of 1 OKOe to produce a compression-molded body. After debinding the compressed body in vacuum at 150°C for 3 hours, the purity was 99.999 at 1200°C for 1 hour.
Sintering in a 99% argon atmosphere followed by 117
Heat treatment was performed at 0°C for 1 hour. Then 850°CX
Multi-stage aging treatment was performed for 30 minutes at 800°C for 1 hour, 700°C for 3 hours, and 600°C for 10 hours. Next, the magnetic properties of Sample E of the present invention thus obtained were measured and the amount of oxygen and carbon contained was analyzed. The results were as shown in Table 1.

Further, a powder prepared in the same manner as Sample E was press-molded in a magnetic field of 1.10 KOe after removing the solvent in an argon gas stream.

This compressed body was subjected to debinding treatment in vacuum at 150''C::X for 30 minutes, and then subjected to the same heat treatment as sample E in an argon atmosphere with a purity of 99.99%.Magnetic properties of sample F for comparison. The measurement results and the analysis results of oxygen and carbon content are as shown in Table 1.

That is, when comparing sample E and sample F of the present invention, sample F
It can be seen that even if the oxygen content is 0.25 wt% or less, the carbon content exceeds 0.05 wt%, so the iHc decreases and the magnetic properties are significantly deteriorated.

Table 1 Applicant: Sumitomo Special Metals Co., Ltd.

Claims (1)

[Claims] 1. The composition is R (R is yttrium, one or more rare earth elements including cerium, samarium, praseodymium, and mitsch metal) in weight ratio 20 to 301, the balance being Co and a part of Co. One or more types of Fe, Ni,
In rare earth cobalt magnets substituted with transition metal elements such as Cu, the oxygen content is 0.25% or less, the carbon content is 0.05% or less, and the total amount of oxygen and carbon is 0.25%.
It is characterized by being less than 100%. Permanent magnetic material. 2 Its composition is R ('R is one or more rare earth elements including yttrium, cerium, samarium, praseodymium, and mitsch metal) 20 to 30% by weight, and the balance is one or more types of Co and a part of CO. of Fe, Ni,
In a rare earth cobalt-based magnet in which a transition metal element such as CB is substituted, a portion of the transition metal element is further replaced with Mu or V. Ti + Nb + Replaced with one or more elements among the various elements Zr, Ta, Hf, oxygen content 0.25% or less, carbon content 0.05% or less, and the total amount of oxygen and carbon is 0.25 % or less.