JPH04323801A - Rare-earth magnet - Google Patents

Abstract

PURPOSE:To provide a rare-earth magnet including no quantity of or a small quantity of cobalt, and having a Curie temperature and a high magnetic characteristic. CONSTITUTION:A rare-earth magnet is characterized in comprising 7 to 25at% of R (provided that R is a kind or two kinds or more of rare-earth elements including Y), 2 to 25at% of N, 1 to 20at% of C, 0.1 to 18at% of T (provided that T is a kind or two kinds or more of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Ni, and Cu), and the residue Fe, or in replacing a part of Fe with Co.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel rare earth magnet, particularly a rare earth-iron-nitrogen-carbon system (hereinafter referred to as "R-Fe-N-C system") rare earth magnet.

0002

[Prior Art] Conventionally, permanent magnets have been made of Co.
Representative examples include alnico magnets containing 30% by weight, hard ferrite magnets containing Fe oxide as a main component, and rare earth cobalt magnets containing 50 to 65% by weight Co and Sm as the rare earth element (R). ing.

However, the raw material situation for Co used in alnico magnets and rare earth cobalt magnets has become unstable, and Sm used in rare earth cobalt magnets has a low content in rare earth minerals and is extremely expensive. , hard ferrite magnets are the mainstream of permanent magnets.

However, rare earth cobalt magnets have much higher magnetic properties than other magnets, and are considered to be essential magnets mainly for small, high-value-added magnetic circuits.

[0005] Therefore, there is an urgent need to develop rare earth magnets that do not contain Co or Sm, and research has been carried out on various rare earth magnets.

[0006] Under these circumstances, the development of rare earth magnets has progressed, and recently, rare earth magnets that do not contain Co or Sm, such as Nd, Pr, Dy,
At least one of the rare earth elements Ho, Tb 8-3
A rare earth permanent magnet of a magnetically anisotropic sintered body consisting of 0 at%, B2 to 28 at%, and the balance substantially Fe, and N
At least one of the rare earth elements d, Pr, Dy, Ho, and Tb, and La, Ce, Pm, Sm, Eu, Gd,
A total of 8 to 30 at% of at least one of the rare earth elements Er, Tm, Yb, Lu, and Y, and B2 to 28 at%
A rare earth permanent magnet of a magnetically anisotropic sintered body consisting of a magnetically anisotropic sintered material and the remainder substantially Fe was proposed (Japanese Patent Publication No. 34242/1983).

[0007] Furthermore, a method for manufacturing permanent magnets with high magnetic properties using a liquid quenching method has been proposed (Japanese Patent Application Laid-Open No.
No. 9-64739).

[0008]

[Problem to be solved by the invention] The above-mentioned R-Fe-B
The system magnet has high magnetic properties at room temperature. However, since the Curie temperature is approximately 300° C., the temperature characteristics are poor.

An object of the present invention is to provide a rare earth magnet that does not contain Co or contains only a small amount of Co and has a high Curie temperature and high magnetic properties.

0010

[Means for Solving the Problems] In order to achieve the above object, the rare earth magnet according to the present invention contains 7 to 25 at% of R (wherein R is one or more rare earth elements including Y),
2-25 at% N, 1-20 at% C, 0.1-1
8 at% T (however, T is Ti, Zr, Hf, V, Nb,
one or more of Ta, Cr, Mo, W, Mn, Ni, and Cu), with the remainder being Fe, and the present invention also provides for the Fe to be replaced with Co in the range of 0<Co/Fe≦1. A replacement version is also provided.

Rare earth magnet (R-Fe-N-
In C-based magnets, high magnetic properties occur in the above-mentioned composition range.

[0012] In order to ensure such an effect, it is necessary to contain each component in the above amounts. To explain the reasons in order, first, the content of R, which is a rare earth element including yttrium Y, is 7. ~25at% is required. That is, it needs to be at least 7 at%, but if the R content is too large, the residual magnetic flux density (Br) maximum energy product ((BH) max) will decrease, so 25a
It is important that the R content is t% or less, and the preferable R content is 9 to 22 at%.

Furthermore, if the content of nitrogen N becomes too low, the coercive force (iHc), Br, and (BH)max decrease. On the other hand, if the N content becomes too large, iHc decreases, so N needs to be 2 to 25 at%. Preferably it is 5 to 20 at%.

Furthermore, if the carbon C content becomes too low, iHc, Br, (BH)max will become small, and if the C content becomes too large, Br, (BH)max will become small. Therefore, C needs to be 1 to 20 at%. Preferably it is 3 to 17 at%.

By the way, if a magnetically soft phase exists in the alloy, it is difficult to form a magnet. Therefore, it is necessary to suppress the soft phase in the alloy. Therefore, Ti,
Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn,
By containing T, which is one or more transition elements among Ni and Cu, precipitation of α-Fe, which is a soft phase, can be suppressed. Therefore, due to the inclusion of T, iH
c is expected to be improved.

[0016] If the T content becomes too low, iHc becomes small. Also, if the T content becomes too large, Br, (B
H) max becomes smaller. Therefore, the content of T is 0.1
It is necessary to set it to 18 at%. Preferably 0.5~
It is 18at%.

In principle, the rare earth magnet of the present invention does not contain cobalt, which is not a good raw material, but since high magnetic properties can be obtained by containing cobalt, a small amount of cobalt can be obtained by replacing a part of Fe with Co. Cobalt can also be contained. In that case, as the amount of Co substitution increases, the Curie temperature increases, but if the amount of Co substitution increases too much, iHc decreases. Therefore, when partially replacing Fe with cobalt, it is necessary to replace Fe with Co within the range of 0<Co/Fe≦1.

[0018] In producing a rare earth magnet with such components, first components other than nitrogen, ie, R, C, T, F
(e) A mixture is prepared by mixing each component of Co in a predetermined ratio, and this is heated to a high temperature in an arc melting furnace or the like to melt it, and after cooling, it is pulverized.

The obtained powder is then heated to a high temperature in a nitrogen gas stream to be treated with nitrogen. A certain amount of an organic binder such as an epoxy resin is kneaded into the nitrogen-containing powder obtained here, compression molded by applying a magnetic field, and then cured and bonded magnetized to produce a product.

[0020]

[Examples] Examples of rare earth magnets according to the present invention are given below. However, the invention should not be construed as being limited by this example. In this example, the manufacturing method of each magnet is also shown, and the content of one of the components or Co/Fe
The magnetic properties were measured and shown when changing the ratio. It is clear from this that good magnetic properties cannot be obtained outside the specified content of each component or the above-mentioned Co/Fe ratio.

[Example 1] The following first step (pre-step):
Through the second step (nitrogen treatment step) and third step (bond magnetization step), the first
Various changes were made as shown in the table, N: 8at%, C: 5a
An R-Fe-N-C rare earth magnet according to the present invention was prepared having a composition of 5 at% Ti, 10 at% Co, and the balance Fe.

First step (pre-step): The required alloying elements (Sm, Fe, C, Ti, Co) are melted in an arc melting furnace, and depending on the Sm content, 970 to 1
Solution treatment was performed at 020°C for 24 hours. Thereafter, it was ground to an average particle size of about 3 μm using a grinder.

Second step (nitrogen treatment step) The powder obtained in the first step was treated with nitrogen at 550° C. in 1 atm N2 gas for 2 to 8 hours depending on the Sm content.

Third step (bonded magnetization step) 3 wt% epoxy resin was kneaded into the N-containing powder obtained in the second step, and the mixture was molded under a molding pressure of 3 ton/cm2 in a magnetic field of 15 KOe.
It was compression molded and then cured.

R according to the present invention obtained as described above
-iHc, Br, (BH) of Fe-N-C rare earth magnet
max was measured and the results are shown in Table 1 in comparison with the Sm content.

[0026] As is clear from Table 1, when the Sm content is less than 6 at%, iHc is small, and when the Sm content exceeds 25 at%, Br, (BH)max becomes small.

[Example 2] The following first step (pre-step):
Through the second step (nitrogen treatment step) and third step (bond magnetization step), N was varied in the range of 1 to 27 at% as shown in Table 2, Sm: 13 at%, C: 5
An R-Fe-N-C rare earth magnet according to the present invention was prepared having a composition of Co: 5 at%, V: 5 at%, and Fe: the balance.

1st step (pre-step) The required alloying elements (Sm, Fe, Co, V, C) are melted in an arc melting furnace to a melting point of 960 to 100, depending on the alloy composition.
Solution treatment was performed at 0°C for 24 hours. Thereafter, it was ground to an average particle size of about 3 μm using a grinder.

Second step (nitrogen treatment step) The powder obtained in the first step was treated with nitrogen at 550° C. in 1 atm N2 gas for 1 to 16 hours depending on the N content.

Third step (bond magnetization step) Same as Example 1 R-Fe-N- according to the present invention obtained in the above manner.
The iHc, Br, and (BH)max of the C-based rare earth magnet were measured, and the results are shown in Table 2 in comparison with the N content.

As is clear from Table 2, when the N content is less than 2 at %, iHc, Br, and (BH) max are small, and when the N content exceeds 25 at %, iHc becomes small.

[Example 3] The following first step (pre-step):
Through the second step (nitrogen treatment step) and third step (bond magnetization step), C was varied in the range of 0 to 22 at% as shown in Table 3, Sm: 11 at%, N: 7
An R-Fe-N-C rare earth magnet according to the present invention having a composition of Nb: 6 at% and Fe: the balance was prepared.

First step (pre-step) The required alloying elements (Sm, Fe, C, Nb) are melted in an arc melting furnace and heated to 960 to 1010°C depending on the C content.
Solution treatment was carried out for 24 hours. Thereafter, it was ground to an average particle size of about 3 μm using a grinder.

Second step (nitrogen treatment step) The powder obtained in the first step was treated with nitrogen at 550° C. for 1 to 4 hours depending on the C content in 1 atm N2 gas.

Third step (bonded magnetization step) Same as Example 1 R-Fe-N- according to the present invention obtained in the above manner.
The iHc, Br, and (BH)max of the C-based rare earth magnet were measured, and the results are shown in Table 3 in comparison with the C content.

[0036] As is clear from Table 3, when the C content is less than 1 at%, iHc, Br, and (BH)max are small, and when the C content exceeds 20 at%, iHc becomes small.

[Example 4] The following first step (pre-step):
Through the second step (nitrogen treatment step) and third step (bond magnetization step), Sm is 7 to 13 at% and Pr is 0 to 6
at% (however, Sm+Pr=13at%)
Various changes were made as shown in the table, N: 10 at%, C: 5
An R-Fe-N-C rare earth magnet according to the present invention having a composition of 4 at%, Hf: 4 at%, and Fe: the balance was prepared.

First step (pre-step): The required alloying elements (Sm, Pr, Fe, C, Hf) are melted in an arc melting furnace, and depending on the Pr content, 960 to 1
Solution treatment was performed at 000°C for 24 hours. Thereafter, it was ground to an average particle size of about 3 μm using a grinder.

Second step (nitrogen treatment step) The powder obtained in the first step was treated with nitrogen at 550° C. for 4 to 5 hours depending on the Pr content in 1 atm N 2 gas.

Third step (bonded magnetization step) Same as Example 1 R-Fe-N- according to the present invention obtained in the above manner.
The iHc, Br, and (BH)max of the C-based rare earth magnet were measured, and the results are shown in Table 4 in comparison with the Pr content.

As is clear from Table 4, the magnetic properties change depending on the Pr content of Sm, but it can be seen that practically sufficient magnetic properties can be obtained. This clearly shows that R (including Y) other than Sm is also effective.

[Example 5] The following first step (pre-step):
After the second step (nitrogen treatment step) and third step (bond magnetization step), the T shown in Table 5 is used,
Sm: 15at%, N: 8at%, C: 5at%, T:
An R-Fe-N-C rare earth magnet according to the present invention having a composition of 8 at% Co, 10 at% Co, and the balance Fe was prepared.

First step (pre-step) The required alloying elements (Sm, Fe, Co, C, T) are melted in an arc melting furnace, and solution treatment is performed at 980 to 1000°C for 24 hours depending on T. Ta. Thereafter, it was ground to an average particle size of about 3 μm using a grinder.

Second step (nitrogen treatment step) The powder obtained in the first step was heated at 550° C. in 1 atm N2 gas for 3 to 4 hours depending on T.
Nitrogen treatment was performed for hours.

Third step (bond magnetization step) Same as Example 1 R-Fe-N- according to the present invention obtained in the above manner.
The iHc, Br, and (BH)max of the C-based rare earth magnet were measured, and the results are shown in Table 5 in comparison with T.

As is clear from Table 5, the magnetic properties change as the type of T changes, but it can be seen that practically sufficient magnetic properties can be obtained with any type of T.

[Example 6] The following first step (pre-step):
Through the second step (nitrogen treatment step) and third step (bond magnetization step), Ti is added to the sixth
Various changes were made as shown in the table, Sm: 11 at%, N:
An R-Fe-N-C rare earth magnet according to the present invention having a composition of 8 at%, C: 7 at%, Co: 8 at%, and Fe: the balance was prepared.

First step (pre-step): The required alloying elements (Sm, Fe, Co, C, Ti) are melted in an arc melting furnace, and depending on the Ti content, 980 to 1
Solution treatment was performed at 020°C for 24 hours. Thereafter, it was ground to an average particle size of about 3 μm using a grinder.

Second step (nitrogen treatment step) The powder obtained in the first step was treated with nitrogen at 500° C. in 1 atm N2 gas for 3 to 6 hours depending on the Ti content.

Third step (bond magnetization step) Same as Example 1 R-Fe-N- according to the present invention obtained in the above manner.
The iHc, Br, and (BH)max of the C-based rare earth magnet were measured, and the results are shown in Table 6 in comparison with the Ti content.

As is clear from Table 6, when the Ti content is 0.1a
If the Ti content is less than t%, iHc will be low, and if the Ti content exceeds 18 at%, Br, (BH)max will become small.

[Example 7] The following first step (pre-step):
Through the second step (nitrogen treatment step) and third step (bond magnetization step), Co/Fe was varied in the range of 0 to 1.1 as shown in Table 7, and Sm: 10 at% ,
R-Fe-N- according to the present invention having a composition of N: 10 at%, C: 10 at%, W: 5 at%, and the balance Fe and Co.
A C-based rare earth magnet was prepared.

First step (pre-step): The required alloying elements (Sm, Fe, Co, C, W) are melted in an arc melting furnace, and the
Solution treatment was performed at 020°C for 24 hours. Thereafter, it was ground to an average particle size of about 3 μm using a grinder.

Second step (nitrogen treatment step) The powder obtained in the first step was treated with nitrogen at 550° C. in 1 atm N2 gas for 5 to 6 hours depending on Co/Fe.

Third step (bond magnetization step) Same as Example 1 R-Fe-N- according to the present invention obtained in the above manner.
The iHc and Br(BH)max of the C-based rare earth magnet were measured, and the results are shown in Table 7 in comparison with Co/Fe. The results of Curie temperature measurements are also shown.

As is clear from Table 7, the Curie temperature increases as Co/Fe increases, but as Co/Fe increases
．． When it exceeds 0, iHc becomes small.

[0057] R-Fe-N-C rare earth magnet of the present invention (
The Curie temperature of Co/Fe=0) is the same as that of conventional R-Fe-B.
It is approximately 150°C higher than the Curie temperature of rare earth magnets.

[0058]

Effects of the Invention As detailed above, R-
According to the Fe--N--C rare earth magnet, high magnetic properties can be ensured without containing a large amount of Co unlike conventional magnets. Furthermore, it exhibits a high Curie temperature.

Claims (2)

[Claims] Claim 1: 7 to 25 at% R (wherein R is one or more rare earth elements including Y), 2 to 25 at% N, 1 to 20 at% C, 0.1 to 18 at% T (where T is Ti, Zr, Hf, V, Nb, Ta, Cr, Mo
, W, Mn, Ni, or one or more of Cu)
, the balance being Fe. 2. The Fe is C in the range of 0<Co/Fe≦1.
The rare earth magnet according to claim 1, characterized in that o is replaced with o.