JP2000234151A - R-Fe-B rare earth permanent magnet material - Google Patents

Abstract

(57) Abstract: An R-Fe-B-based rare earth permanent magnet material excellent in both high coercive force and residual magnetic flux density is provided. SOLUTION: In weight percentage, 28 to 35% R (R is N
one or two selected from d, Pr, Dy, Tb, and Ho
Or more rare earth elements), 0.1 to 3.6% Co, 0.9
~ 1.3% B, 0.05-1.0% Al, 0.02-
0.25% Cu, 0.02-0.3% Zr and / or C
r, 0.03-0.1% C, 0.1-0.8% O, 0.
002-0.02% N, the balance being Fe and unavoidable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an R--Fe--B rare earth permanent magnet material having significantly improved magnetic properties.

[0002]

2. Description of the Related Art Rare earth permanent magnets are widely used in the field of electric and electronic equipment because of their excellent magnetic properties and economical efficiency. Among the rare earth permanent magnets, R-Fe-B based rare earth permanent magnets have a lower amount of raw material costs because Nd, which is a main element, is more abundant than Sm and does not use a large amount of Co, as compared with rare earth cobalt magnets. It is an extremely excellent permanent magnet having magnetic properties far superior to rare earth cobalt magnets.

Hitherto, various attempts have been made to improve the magnetic properties of the R-Fe-B rare earth permanent magnet. Specifically, in order to obtain a stable coercive force, T
Examples in which i, Ni, Bi, V, etc. are added (JP-A-59-64)
733, JP-A-59-132104),
Examples in which the magnetic properties are improved by adding 0.02 to 0.5 at% of Cu, the range of the optimum temperature of the heat treatment is widened, and the manufacturing efficiency is improved (Japanese Patent Laid-Open No. 1-219143).
Japanese Patent Application Laid-Open No. 1-21), an example in which the corrosion resistance is improved by adding 0.2 to 0.5 at% of Cr.
No. 9142).

[0004]

SUMMARY OF THE INVENTION The present inventors have improved the magnetic characteristics by adding a new element to the Cu-containing R-Fe-B-based rare earth permanent magnet described in [Background Art]. I tried to improve it further. However, when another element is newly added, in most cases, even if the coercive force (iHc) is increased, the residual magnetic flux density (Br) is reduced. Was difficult. An object of the present invention is to provide an R-Fe-B-based rare earth permanent magnet material having high coercive force and residual magnetic flux density.

[0005]

Means for Solving the Problems The present inventors have proposed an R-Fe
As a result of intensive studies on the types and amounts of newly added elements from among a huge number of elements in -B rare earth permanent magnets,
It has been found that the coercive force and the residual magnetic flux density both increase in a certain range of composition to which Co, Al, Cu, Zr and / or Cr are added, and the present invention has been completed. That is, the present invention provides a method for preparing a composition in which R = 28-35%
(R is 1 selected from Nd, Pr, Dy, Tb, Ho)
Species or two or more rare earth elements), Co = 0.1 to 3.6
%, B = 0.9-1.3%, Al = 0.05-1.0
%, Cu = 0.02 to 0.25%, Zr and / or Cr
= 0.02-0.3%, C = 0.03-0.1%, O =
0.1 to 0.8%, N = 0.002 to 0.02%, the balance being Fe and inevitable impurities.
Fe-B based rare earth permanent magnet material.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The R-Fe-B rare earth permanent magnet material of the present invention has the above-mentioned composition, has a high residual magnetic flux density and a coercive force, and is excellent also in terms of squareness. ing. In the present invention, R is Nd, Pr, Dy, T
b, one or more rare earth elements selected from Ho, the content of which is 28 to 35% (% is weight percentage,
The same applies hereinafter). If the R content is less than 28%, the coercive force will be significantly reduced, and if it is more than 35%, the residual magnetic flux density will be significantly reduced.

[0007] When a part of Fe constituting the present invention is replaced with Co, the Curie temperature (Tc) is improved. In the present invention, the content of Co is in the range of 0.1 to 3.6%. If it is less than 0.1%, the effect of improving the Curie temperature is not so much recognized, and if it exceeds 3.6%, it is disadvantageous in terms of cost.

The content of B constituting the present invention is 0.9 to 0.9%.
The range is 1.3%. If it is less than 0.9%, the coercive force will decrease significantly, and if it exceeds 1.3%, the residual magnetic flux density will decrease significantly.

Al constituting the present invention is a compositional element effective for increasing the coercive force without increasing the cost. Al
Is in the range of 0.05 to 1%. If it is less than 0.05%, the coercive force hardly increases, and
%, The residual magnetic flux density is greatly reduced.

[0010] As described above, Cu constituting the present invention imparts high magnetic properties to the R-Fe-B-based rare earth permanent magnet. In the present invention, the content of Cu is 0.02 to 0.2.
The range is 5%. If it is less than 0.02%, the coercive force hardly increases, and if it exceeds 0.25%, the residual magnetic flux density greatly decreases.

Zr and Cr constituting the present invention are very effective when added together with Cu, particularly in increasing the coercive force. In the present invention, the content of Zr and / or Cr is in the range of 0.02 to 0.3%. 0.02%
If it is less than, the coercive force hardly increases, and
If it exceeds 0.3%, the residual magnetic flux density is greatly reduced. In particular, Zr is 0.03 to 0.3%, and Cr is 0.02 to 0.3%.
It is preferable to add 25%.

In the present invention, the oxygen content is from 0.1 to
The range is 0.8%. If it is less than 0.1%, oversintering is apt to occur, and the squareness is also reduced. On the other hand, 0.8%
If it exceeds 300, both the sinterability and the squareness will be reduced. The carbon content is in the range of 0.03 to 0.1%. If it is less than 0.03%, oversintering is likely to occur, and the squareness will also decrease.
On the other hand, if it exceeds 0.1%, both the sinterability and the squareness deteriorate. The nitrogen content is in the range of 0.002 to 0.02%. If it is less than 0.002%, oversintering is liable to occur, and the squareness is also reduced. On the other hand, when the content exceeds 0.02%, both the sinterability and the squareness deteriorate.

In order to produce the R-Fe-B rare earth permanent magnet material of the present invention, it may be produced according to a general method for producing an Nd-based magnet. As an example, first, Nd, Fe, B serving as raw materials and additional elements (Co, Al, C
u, Zr, Cr, etc.) are blended in a predetermined ratio, and are subjected to high frequency melting to cast an alloy. In this case, Cu, Z used for manufacturing
r and Cr may be a mixture with Fe or Al used as a raw material. Then, the obtained alloy is roughly pulverized by a jaw crusher or a brown mill or the like, and then finely pulverized by a wet method using an organic solvent using an attritor or a ball mill or a dry method such as a jet mill using nitrogen gas.
The particle size of the fine powder is not particularly limited, but is preferably 1 to 10 μm on average. The obtained fine powder is oriented in the direction of a magnetic field in a magnetic field of about 10 kOe, and is press-formed at a pressure of about 0.2 to ² ton / cm ² . Then, the compact formed by press molding is subjected to a high vacuum or an inert gas in a range of 1,000 to
Sinter at 1,200 ° C. for 1 to 2 hours, and further heat-treat at a temperature lower than the sintering temperature (about 600 ° C.). Thereby, the R-Fe-B-based rare earth permanent magnet material of the present invention is obtained. In the present invention, the oxygen content is controlled by changing the oxygen content of the atmosphere during pulverization or from the raw material, and the carbon content is determined by using a raw material having an extremely low carbon content when blending the raw material, It is controlled by using a raw material having an extremely high content. The R-Fe-B rare earth permanent magnet material is further processed and surface-treated to obtain an R-Fe-B rare earth permanent magnet. In the production of the present invention, 0.1 is an unavoidable impurity contained in the raw materials used or mixed in the production process.
2% or less of La, Ce, Sm, Ni, Mn, S
i, Ca, Mg, S, and P do not impair the effects of the present invention.

[0014]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it should not be construed that the present invention is limited thereto. (Example 1, Comparative Example 1) Nd, Dy,
Electrolytic iron, Co, ferroboron, Al, Cu, and ferrosilconium were used. And these raw materials are weight ratio (%) 30Nd-1Dy-BAL. Fe-3Co-
1B-0.5Al-0.2Cu-XZr (X = 0-0.
After blending into the composition of 5), high-frequency melting was performed in an alumina crucible and poured into a water-cooled copper mold to obtain ingots of various compositions. Next, these ingots were roughly pulverized with a brown mill and further finely pulverized with a jet mill in a nitrogen stream to obtain a fine powder having an average particle size of about 3 μm. The mixture was mixed with a V-type mixer in a 0.07% nitrogen atmosphere. Thereafter, these fine powders were filled in a mold of a molding apparatus, oriented in a magnetic field of 10 kOe, and press-molded in a direction perpendicular to the magnetic field at a pressure of 1.2 ton / cm ² . The obtained molded body was heated at 1,060 ° C. for 2 hours,
After sintering in an Ar atmosphere, it was cooled and further heat-treated in an Ar atmosphere at 600 ° C. for 1 hour to prepare R—Fe—B rare earth permanent magnet materials of various compositions having different Zr contents. In addition, during the process from the ingot to the sintering, the entire process was performed in a nitrogen atmosphere to reduce the oxygen content. As a result, each content of carbon, oxygen, and nitrogen in the R-Fe-B-based rare earth permanent magnet material is 0.085 to 0.085, respectively.
0.095%, 0.15-0.25%, 0.01-0.
015%. Then, the coercive force (iHc) and the residual magnetic flux density (Br) were measured for these R-Fe-B rare earth permanent magnet materials, and the obtained results are shown in FIG. As a result, as can be seen from FIG. 1, up to a Zr content of 0.3%, the coercive force could be increased without lowering the residual magnetic flux density as compared with the case where no Zr was added. When the amount of Zr added exceeded 0.3%, both the residual magnetic flux density and the coercive force decreased as compared with the case where Zr was not added. Furthermore, when the content of Zr is 0.1%,
The residual magnetic flux density can be increased by 0.2 kG and the coercive force can be increased by 2 kOe, and the magnetic properties have been greatly improved.

Example 2 and Comparative Example 2 The same raw materials and method as those in Example 1 and Comparative Example 1 were used in a weight ratio (%) of 30.5%.
Nd-0.5Tb-BAL. Fe-1Co-1.1B-
Compounded into a composition of 0.8Al-0.1Cu-0.1Zr,
Thereafter, oxygen is contained up to 0.06 to 1.13% and R
-An Fe-B based rare earth permanent magnet material was produced. The carbon content is 0.035-0.045% and the nitrogen content is 0.00
5 to 0.010%. The change in the oxygen content was adjusted by changing the oxygen content in the atmosphere during pulverization and pressing. The squareness ratio of these R-Fe-B rare earth permanent magnet materials was measured, and the obtained results are shown in FIG. As a result, as can be seen from FIG. 2, when the oxygen content was less than 0.1%, oversintering occurred and the squareness ratio was reduced.
On the other hand, when the oxygen content was more than 0.8%, the sinterability deteriorated, and the squareness ratio decreased. That is, it is understood that the oxygen content is preferably 0.1 to 0.8% with respect to the squareness ratio in the magnetic characteristics.

Example 3 and Comparative Example 3 The same raw materials and method as those in Example 1 and Comparative Example 1 were used in a weight ratio (%) of 30.5%.
Nd-1.5Pr-BAL. Fe-2Co-1.1B-
0.7Al-0.1Cu-0.1Zr-XC (X = 0.
01 to 0.12) to prepare an R-Fe-B-based rare earth permanent magnet material. Oxygen content is 0.65-
0.75%, nitrogen content was 0.015 to 0.020%. Then, the squareness ratio of these R-Fe-B rare earth permanent magnet materials was measured, and the obtained result was shown in FIG.
It was shown to. As a result, as can be seen from FIG. 3, when the carbon content was less than 0.03%, oversintering occurred and the squareness ratio was reduced. On the other hand, when the carbon content is more than 0.1%, the sinterability deteriorates, and the squareness ratio decreases. That is, it is understood that the carbon content is preferably 0.03 to 0.1% with respect to the squareness ratio in the magnetic characteristics.

Example 4 and Comparative Example 4 The same raw materials and method as in Example 1 and Comparative Example 1 were used to obtain a weight ratio (%) of 30.5%.
Nd-1.0 Dy-BAL. Fe-2Co-1.1B-
After compounding into a composition of 0.6Al-0.1Cu-0.1Zr,
Nitrogen is contained up to 0.001 to 0.03% and R-Fe
-A B-based rare earth permanent magnet material was produced. The change in the nitrogen content was adjusted by using lots having different nitrogen contents in the raw materials. Each of the contents of carbon and oxygen in the R-Fe-B rare earth permanent magnet material is 0.055.
0.065% and 0.35 to 0.45%. Then, the squareness ratio was measured for these R-Fe-B-based rare earth permanent magnet materials, and the obtained results are shown in FIG. As a result, as can be seen from FIG.
If it is less than 2%, oversintering occurs and the squareness ratio decreases. Also,
If the nitrogen content is more than 0.02%, the sinterability deteriorates,
Squareness ratio decreased. That is, it is understood that the nitrogen content is preferably 0.002 to 0.02% with respect to the squareness ratio in the magnetic characteristics.

Example 5 and Comparative Example 5 As starting materials,
Nd, Dy, electrolytic iron, Co, ferroboron, Al, C
u, ferrochromium was used. And these raw materials are weight ratio (%) 30Nd-1Dy-BAL. Fe
-3Co-1B-0.5Al-0.2Cu-XCr (X
= 0 to 0.5) R-Fe-B-based rare earth permanent magnet materials of various compositions having different Cr contents were prepared in the same manner as in Example 1 except that they were blended in the composition of (= 0 to 0.5). In addition, each content of carbon, oxygen, and nitrogen in the R-Fe-B-based rare earth permanent magnet material is 0.035 to 0.045%, 0.65 to 0.65, respectively.
0.75% and 0.005 to 0.01%. Then, the coercive force (iHc) and the residual magnetic flux density (Br) of these R-Fe-B-based rare earth permanent magnet materials were measured, and the obtained results are shown in FIG. As a result, as can be seen from FIG. 5, up to a Cr content of 0.25%, the residual magnetic flux density was not reduced as compared with the case where no Cr was added.
The coercive force could be increased. Further, even when the amount of added Cr exceeded 0.25%, the residual magnetic flux density was greatly reduced but the coercive force was increased as compared with the case where Cr was not added. Furthermore, when the content of Cr was 0.1%, the residual magnetic flux density could be increased by 0.2 kG and the coercive force could be increased by 2 kOe, and the magnetic properties were greatly improved.

(Example 6, Comparative Example 6) By the same raw materials and method as in Example 5, Comparative Example 5, the weight ratio (%) was 30.5%.
Nd-0.5Tb-BAL. Fe-1Co-1.1B-
0.8Al-0.1Cu-0.1Cr
Then, oxygen is contained up to 0.08 to 1.10% and R
-An Fe-B based rare earth permanent magnet material was produced. The carbon content is 0.035-0.045% and the nitrogen content is 0.00
5 to 0.010%. The change in the oxygen content was adjusted by changing the oxygen content in the atmosphere during pulverization and pressing. The squareness ratio of these R-Fe-B rare earth permanent magnet materials was measured, and the obtained results are shown in FIG. As a result, as can be seen from FIG. 6, when the oxygen content was less than 0.1%, oversintering occurred and the squareness ratio was reduced.
On the other hand, when the oxygen content was more than 0.8%, the sinterability deteriorated, and the squareness ratio decreased. That is, it is understood that the oxygen content is preferably 0.1% to 0.8% with respect to the squareness ratio in the magnetic characteristics.

Example 7 and Comparative Example 7 The same raw materials and method as those in Example 5 and Comparative Example 5 were used in a weight ratio (%) of 30.5%.
Nd-1.5Pr-BAL. Fe-2Co-1.1B-
0.7Al-0.1Cu-0.1Cr-XC (X = 0.
015 to 0.12) to prepare an R-Fe-B-based rare earth permanent magnet material. Oxygen content is 0.65-
0.75%, nitrogen content was 0.015 to 0.020%. Then, the squareness ratio of these R-Fe-B rare earth permanent magnet materials was measured, and the obtained result was shown in FIG.
It was shown to. As a result, as can be seen from FIG. 7, when the carbon content was less than 0.03%, oversintering occurred and the squareness ratio was reduced. On the other hand, when the carbon content is more than 0.1%, the sinterability deteriorates, and the squareness ratio decreases. That is, it is understood that the carbon content is preferably 0.03% to 0.1% with respect to the squareness ratio in the magnetic characteristics.

Example 8 and Comparative Example 8 The same raw materials and method as those in Example 5 and Comparative Example 5 were used in a weight ratio (%) of 30.5%.
Nd-1.0 Dy-BAL. Fe-2Co-1.1B-
After compounding into a composition of 0.6Al-0.1Cu-0.1Cr,
Nitrogen is contained up to 0.001 to 0.03% and R-Fe
-A B-based rare earth permanent magnet material was produced. The change in the nitrogen content was adjusted by using lots having different nitrogen contents in the raw materials. The contents of carbon and oxygen were 0.055 to 0.065% and 0.35 to 0.45%, respectively. Then, the coercive force (iHc) and the residual magnetic flux density (Br) were measured for these R-Fe-B rare earth permanent magnet materials, and the obtained results are shown in FIG. As a result, as can be seen from FIG.
%, Oversintering occurred and the squareness ratio decreased. On the other hand, when the nitrogen content was more than 0.02%, the sinterability deteriorated and the squareness ratio decreased. That is, it is understood that the nitrogen content is preferably 0.002% to 0.02% with respect to the squareness ratio in the magnetic characteristics.

[0022]

According to the present invention, an R-Fe-B rare earth permanent magnet material having high coercive force and residual magnetic flux density can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relationship between a Zr amount, a coercive force (iHc), and a residual magnetic flux density (Br).

FIG. 2 is a diagram showing a relationship between an oxygen amount and a squareness ratio.

FIG. 3 is a diagram showing the relationship between the carbon content and the squareness ratio.

FIG. 4 is a diagram showing the relationship between the amount of nitrogen and the squareness ratio.

FIG. 5 is a diagram showing the relationship between the amount of Cr, coercive force (iHc), and residual magnetic flux density (Br).

FIG. 6 is a diagram showing a relationship between an oxygen amount and a squareness ratio.

FIG. 7 is a diagram showing the relationship between the carbon content and the squareness ratio.

FIG. 8 is a diagram showing the relationship between the amount of nitrogen and the squareness ratio.

Claims (3)

[Claims] 1. R = 28-35% by weight (R is one or more rare earth elements selected from Nd, Pr, Dy, Tb, Ho), Co = 0.1-3. 6%, B = 0.9-1.3%, Al = 0.05-1.0%, Cu = 0.02-0.25%, Zr and / or Cr = 0.02-0.3% C = 0.03 to 0.1%, O = 0.1 to 0.8%, N = 0.002 to 0.02%, R-Fe characterized by being composed of a balance of Fe and unavoidable impurities. -B-based rare earth permanent magnet material. 2. The method according to claim 1, wherein Zr is 0.03 to 0.03.
An R-Fe-B-based rare earth permanent magnet material characterized by being 0.3%. 3. The method according to claim 1, wherein Cr is 0.02 to
An R-Fe-B-based rare earth permanent magnet material characterized by being 0.25%.