JPH0645832B2 - Rare earth magnet manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention has remarkably excellent magnetic properties and is, for example, a permanent magnet for home appliances, audio products, watch parts, automobile parts, precision instruments and the like. The present invention relates to a method for manufacturing a rare earth magnet used for manufacturing a permanent magnet, which can be applied in a wide range of fields using.

(Prior Art) In recent years, the improvement of magnetic properties of permanent magnets has been remarkable as compared with those of the former Alnico-based (Co-Ni-Al-Fe-based) permanent magnets and the like.
It greatly contributes to the miniaturization and high performance of audio products, watch parts, automobile parts, precision instruments, etc.

Conventionally, there are rare-earth-cobalt-based and rare-earth-iron-based permanent magnets having such excellent magnetic properties, and more specifically, RCo ₅ system, R ₂ Co ₁₇ , R-.
Fe-based materials are available.

By the way, in the production of the rare earth magnet, the magnetic alloy powder containing a rare earth metal is molded and then the compact is heated and sintered at a high temperature, but the magnetic alloy powder is very active. Easily oxidizes. Therefore, since the sintering characteristics greatly depend on the influence of a small amount of residual oxygen during sintering, the magnetic characteristics of the permanent magnet are likely to be unstable and non-uniform due to the presence of the residual oxygen.

Therefore, in the conventional case, when sintering the above-mentioned magnetic alloy powder compact, it was performed in a non-oxidizing atmosphere such as a hydrogen atmosphere, an argon atmosphere, or a vacuum.

(Problems to be Solved by the Invention) By sintering a compact of the magnetic alloy powder containing a rare earth metal in a hydrogen atmosphere, a high-density sintered compact can be obtained. Residual magnetic flux density (Br)
Is improved.

However, when sintered in a hydrogen atmosphere, the residual magnetic flux density (Br) is improved as described above, but the coercive force (Hc) is higher than that when sintered in an argon atmosphere or in a vacuum. It had the problem of becoming low.

The present invention has been made by paying attention to the conventional problems as described above, and not only the residual magnetic flux density (Br), which is one of the magnetic characteristics, is excellent after sintering. It is also excellent in coercive force (Hc), which is another factor of magnetic characteristics, and therefore has a maximum energy product ((BH) ma
It is an object of the present invention to provide a method for manufacturing a rare earth magnet, which makes it possible to obtain a rare earth permanent magnet having a large x).

[Structure of the Invention] (Means for Solving Problems) The present invention relates to one of rare earth metals whose basic component contains Y.
1 or 2 or more and 1 of Fe, Co, Ni, Mn
When a magnetic alloy powder consisting of two or more kinds is molded and then the molded body is heated and sintered, the molded body is heated and heated in a hydrogen-containing atmosphere having a hydrogen content of 1% by volume or more, The temperature of the compact is 50 below the sintering temperature of the compact.
The method is characterized in that when a temperature between a low temperature of 0 ° C. and the sintering temperature is reached, the atmosphere is replaced with a non-oxidizing atmosphere having a hydrogen content of less than 1% by volume, and sintering is performed in the atmosphere, followed by cooling. There is.

The rare earth magnet to which the present invention is applied includes one or more rare earth metals containing Y as a basic component and Fe and C.
o, Ni, Mn, and one or more of O, Ni, and Mn. More specifically, when represented by R-M-X-Z, R is a rare earth metal containing Y (that is, Sc. , Y
And lanthanoid), M is one or more of Fe, Co, Ni and Mn, and X is Ti, Zr, Hf, V, Nb,
It is composed of one or more of Ta, Cr, Mo and W, and Z is one or two of B, C, N, Si and P.
It is composed of more than one kind, and in addition, Al, Cu, C
One of rare earth metals containing Y as a basic component, which contains one or more of a and the like.
1 or 2 or more and 1 of Fe, Co, Ni, Mn
One or two or more species.

In the present invention, as described above, one or more rare earth metals whose basic component contains Y and Fe, Co,
A rare earth magnet is manufactured by heating and sintering a compact formed by molding a magnetic alloy powder consisting of one or more of Ni and Mn. The temperature is increased by heating in a hydrogen-containing atmosphere having a hydrogen content of 1% by volume or more. Here, the hydrogen content in the atmosphere is set to 1% by volume or more in order to increase the density of the sintered body so that the residual magnetic flux density (Br) becomes a large value. Then, when the temperature of the molded body is between a temperature 50 ° C. lower than the sintering temperature of the molded body and the sintering temperature, hydrogen is removed from the hydrogen-containing atmosphere in which the hydrogen content is 1% by volume or more. A non-oxidizing atmosphere with a content of less than 1% by volume,
For example, the rare earth permanent magnet is manufactured by replacing the atmosphere with an argon atmosphere or a vacuum atmosphere, then sintering in the non-oxidizing atmosphere and then cooling. Here, the atmosphere after the replacement is made a non-oxidizing atmosphere having a hydrogen content of less than 1% by volume in order to obtain a large coercive force (Hc) after sintering. Further, the atmosphere replacement temperature is set to a temperature lower than the sintering temperature of the molded body by 50 ° C. to the sintering temperature because the residual magnetic flux density (Br) or the coercive force (Hc) is out of this range. Is decreased, and it becomes impossible to obtain a permanent magnet having a large maximum energy product ((BH) max).

The rare earth permanent magnet manufactured in this manner has a high density as in the case of sintering in a hydrogen-containing atmosphere, and the residual magnetic flux density (Br), which is one of the magnetic characteristics, is one of the factors. In addition to being large, the coercive force (Hc), which is another factor of the magnetic characteristics, is large as in the case of sintering in an argon atmosphere or vacuum,
As a result, the maximum energy product ((BH) max) becomes large.

(Example 1, Comparative Example 1) In this Example and Comparative Example, Sm: 25.5 wt%, Cu: 4.2 wt%, Fe: 20.5 wt%, Z
r: 2.4 wt%, Ti: 0.2 wt%, B: 0.00
A magnetic alloy powder composed of 5% by weight and the balance Co was used, and the magnetic alloy powder was used at 1 tonf / c in a magnetic field of 10 KOe.
Molding was performed by molding at a pressure of m ₂ .

Next, the molded body is heated to 200 ° C. in a vacuum, then replaced with a hydrogen-containing atmosphere having a hydrogen content of 90% by volume, and heated and heated in the hydrogen-containing atmosphere. When each point (A to G) shown in FIG. 1 is reached, the atmosphere is replaced with an argon atmosphere, and the temperature is 1210 ° C. in the argon atmosphere.
Sintering was performed for 1 hour, and after the sintering, a solution treatment of heating at 1170 ° C. for 2 hours was performed, followed by rapid cooling.

Next, the magnetic properties and the density of each of the rare earth magnets thus manufactured were measured, and the results shown in Table 1 were obtained.

As shown in Table 1, a magnetic alloy powder compact is heated and heated in a hydrogen-containing atmosphere, and the heating temperature of the compact is 50 ° C. lower than the sintering temperature of the compact to the sintering temperature. When the atmosphere is replaced by an argon atmosphere and the sintering is performed in the argon atmosphere (Nos. 4 and 5), the sintering is performed in the hydrogen atmosphere shown in Comparative Example 2 described later. High density and residual magnetic flux density (Br)
And a high value of coercive force ( _B Hc, _I Hc) as in the case of sintering in an argon atmosphere and a vacuum shown in Comparative Example 2 described later, and the maximum energy product (( It is clear that a permanent magnet having a large BH) max) could be manufactured.

On the other hand, when the atmosphere was replaced with an argon atmosphere earlier than the above and sintered (No. 1, 2, 3), and when the atmosphere was replaced with an argon atmosphere later than the above (No.
6 and 7), it is apparent that it was not possible to manufacture a permanent magnet having a large maximum energy product ((BH) max) as shown in the above examples.

Comparative Example 2 In this comparative example, a magnetic alloy powder having the same composition as in Example 1 and Comparative Example 1 was used, and this magnetic alloy powder was similarly molded in a magnetic field to obtain a molded body.

Next, the molded body was vacuum-heated to 200 ° C., and then partly heated to 1210 ° C. in a hydrogen atmosphere consisting of 80% hydrogen-20% argon, and sintered at 1210 ° C. for 1 hour. A solution treatment of heating at 1170 ° C. for 2 hours was performed and the solution was rapidly cooled. The other part was heated to 1210 ° C. in an argon atmosphere, sintered at 1210 ° C. for 1 hour, then heated at 1170 ° C. for 2 hours for solution treatment, and then rapidly cooled. Further, the rest is heated to 1210 ° C. in vacuum and sintered at 1210 ° C. for 1 hour, and then 1170.
It was subjected to a solution treatment of heating at ℃ for 2 hours and quenched.

Next, the magnetic properties and the density of each of the rare earth magnets thus manufactured were measured, and the results shown in Table 2 were obtained.

As shown in Table 2, when sintered in a hydrogen atmosphere, an argon atmosphere and a vacuum, excellent magnetic properties as shown in Example 1 could not be obtained.

(Example 2, Comparative Example 3) In this Example and Comparative Example, a magnetic alloy powder consisting of Nd: 34.0% by weight, B: 1.2% by weight, and the balance Fe was used. A molded body was manufactured by molding at a pressure of 1 tonf / cm ₂ in a magnetic field of 10 KOe.

Next, the molded body is heated to 200 ° C. in a vacuum, then replaced with a hydrogen-containing atmosphere having a hydrogen content of 90% by volume, and heated and heated in the hydrogen-containing atmosphere. When each point (H to L) shown in FIG. 2 is reached, the atmosphere is replaced with an argon atmosphere and 1110 ° C. in the argon atmosphere.
Sintered for 1 hour, and after sintering up to 800 ℃ 2 ℃ / mi
It was cooled at a cooling rate of n, and was rapidly cooled after reaching 800 ° C.

Next, the magnetic properties and the density of each of the rare earth magnets thus manufactured were measured, and the results shown in Table 3 were obtained.

As shown in Table 3, a magnetic alloy powder compact is heated and heated in a hydrogen-containing atmosphere, and the heating temperature of the compact is 50 ° C. lower than the sintering temperature of the compact to the sintering temperature. When it is replaced with an argon atmosphere and sintered in the argon atmosphere (No. 22, 23),
High values of density and residual magnetic flux density (Br) are obtained as in the case of sintering in hydrogen atmosphere, and high values of coercive force as in the case of sintering in argon atmosphere and vacuum. It is clear that ( _B Hc, _I Hc) was obtained, and a permanent magnet having a large maximum energy product ((BH) max) could be manufactured.

On the other hand, when the atmosphere is replaced with an argon atmosphere earlier than the above and sintered (No. 21) and when the atmosphere is replaced with an argon atmosphere later than the above (No. 24, 2).
In 5), the above No. It is clear that it was not possible to manufacture a permanent magnet with a maximum energy product ((BH) max) as high as 22,23.

EFFECTS OF THE INVENTION As described above, in the present invention, the basic component is Y
One or more of the rare earth metals containing Fe and Fe,
When a magnetic alloy powder consisting of one or more of Co, Ni and Mn is molded and then the molded body is heated and sintered, the molded body contains hydrogen containing 1% by volume or more of hydrogen. Non-oxidizing with a hydrogen content of less than 1% by volume when the temperature of the molded body is raised to 50 ° C. lower than the sintering temperature of the molded body to the sintering temperature by heating in an atmosphere. Since the atmosphere is replaced and the material is sintered in the atmosphere and then cooled, a high density and residual magnetic flux density (Br) can be obtained at the same time as in the case of sintering in the conventional hydrogen atmosphere, and at the same time, It is possible to manufacture a rare earth magnet having a high coercive force (Hc), a large maximum energy product ((BH) max), and excellent magnetic properties as in the case of sintering in an argon atmosphere or in a vacuum. Yes, home appliances, acoustic products , In which can lead to very excellent effect that it is possible to realize clock parts, auto parts, the size and weight and high performance of precision equipment, etc. from the surface of the permanent magnet.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a heating and atmosphere substitution pattern of a magnetic alloy powder compact used in Example 1 and Comparative Example 1 of the present invention, and FIG. 2 is employed in Example 2 and Comparative Example 3 of the present invention. It is explanatory drawing which shows the heating of a magnetic-alloy powder compact, and an atmosphere substitution pattern.

Claims (1)

[Claims] 1. One of rare earth metals whose basic component contains Y.
1 or 2 or more and 1 of Fe, Co, Ni, Mn
When one or two or more magnetic alloy powders are molded and then the molded body is heated and sintered, the molded body is heated and heated in a hydrogen-containing atmosphere having a hydrogen content of 1 vol% or more, The temperature of the compact is 50 below the sintering temperature of the compact.
A rare earth magnet characterized by being replaced with a non-oxidizing atmosphere having a hydrogen content of less than 1% by volume when the temperature is between ℃ lower and the sintering temperature, followed by sintering in the atmosphere and then cooling. Manufacturing method.