JPH04359404A - Rare earth iron-boron based permanent magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a rare earth iron based permanent magnet possessing a strong residual magnetic flux density and a strong coercive force, as well as a magnetization curve superior in rectangularity. CONSTITUTION:A rare earth iron-boron based permanent magnet is composed of a sintered body which is prepared by the addition of, parts by weight, 0.01-1.0 zinc oxides and 0.1-2.0 of one or two, or more, types of elements selected from inorganic oxides: namely, Al2O3, SiO2, TiO2, V2O3, Cr2O3, MnO2, Fe2O3, CoO, NiO, CuO2, Ga2O3, GeO2, ZrO2, Nb2O5, MoO3, SnO2, Sb2O5, HfO2, Ta2O5, WO3, and Bi2O3, into 100 parts by weight of rare earth iron-boron alloy expressed by the equation of RxByCozFe100-x-y-zMw, wherein R is a rare earth element, and M represents one or two, or more, types of elements selected from Al, Si, Ti, V, CR, Mn, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Sn, Sb, Hf, Ta, W, and Bi. The factors of the equation are defined, in atomic percent, as 8<=X<=30, 2<=Y<=28, 0<=Z<=20, and 0<=W<=4.0. And the prepartaion method of the above magnet is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth iron boron permanent magnet having a novel composition and a method for manufacturing the same.

0002

[Prior Art] Rare earth iron boron permanent magnets have better potential magnetic properties than other magnets, and they can be used to improve the composition of magnet alloys, improve the orientation of alloy powder using lubricants, and optimize heat treatment conditions. As a result of research and development, it has now become possible to obtain properties with a maximum energy product exceeding 40 MGOe at room temperature. However, in recent years, there has been a demand for smaller electronic devices and higher efficiency, and applications such as motors that are subject to extremely large reverse magnetic fields have increased, and magnetic materials with even higher characteristics and higher coercive force are required.

0003

[Problems to be Solved by the Invention] One of the problems is that rare earth oxides (Dy2O3, Tb4O7, Ho2O3
, Pr2O3, Nd2O3, etc.) mixed in an atomic percentage of 0.1 to 15% and sintered after magnetic field orientation molding increases the coercive force and reduces the residual magnetic flux density more than adding it as a metal. It is possible to keep it small (Japanese Patent Application Laid-open No. 61-253805, 61-2
(See No. 89605). In addition, 0.0% by weight of an oxide powder of at least one kind of elements belonging to Group 2A is added to the R-Fe-B alloy powder or a mixed powder having the same composition.
It is said that coercive force can be significantly improved by blending 5 to 1.5% and subjecting it to mixing, molding, firing, and heat treatment (see JP-A-62-134906). Separately R-Fe
The coercive force can be increased by adding 1% by weight or less of a substance that softens or melts at a lower temperature than the melting point of the alloy, such as lead oxide, bismuth oxide, silicon oxide, etc., to the -B or R-Fe-Co-B compound. It is said that it is possible to manufacture permanent magnet materials with increased
51542). The magnetic properties of the rare earth magnets according to the known techniques described above are not necessarily well-balanced, and further improvements in absolute values have been desired. The present invention was made in view of these points, and its purpose is to
Both residual magnetic density and coercive force are high in B-series permanent magnets,
Another object of the present invention is to provide a permanent magnet whose magnetization curve has high squareness.

0004

[Means for Solving the Problem] In order to solve the problem, the present inventors added various inorganic oxides to the R-Fe-B alloy composition and studied the effects on the magnetic properties. , the present invention was completed after carefully examining various conditions, and a)
Formula RX BYCoZFe100-X-Y-Z-WM
W (wherein, R is a rare earth element, M is Al, Si, Ti
, V, Cr, Mn, Ni, Cu, Zn, Ga, Ge, Z
r, Nb, Mo, Sn, Sb, Hf, Ta, W, Bi
Represents one or more elements selected from the following in atomic percentage: 8≦X≦30, 2≦Y≦28, 0≦
Z≦20, 0≦W≦4) Rare earth iron boron alloy 100 parts by weight b) Zinc oxide 0
．． 01 to 1.0 parts by weight, and c) one or more selected from the following inorganic oxides: 0.1 to 2.
A rare earth iron boron permanent magnet characterized by a sintered body containing 0 parts by weight. Al2O3, SiO2, TiO2,
V2O3, Cr2O3, MnO2, Fe2O3, CoO
, NiO, CuO2, Ga2O3, GeO2, ZrO2
, Nb2O5, MoO3, SnO2, Sb2O5, Hf
O2, Ta2O5, WO3, Bi2O3. and the above a) formula RX BYCoZFe100-X-Y-Z-
When pulverizing a rare earth iron boron alloy represented by W MW , (b) zinc oxide and (c) an inorganic oxide are added, mixed, co-pulverized, sintered after orientation molding in a magnetic field, and then heat treated. The gist of this paper is a method for manufacturing iron-boron permanent magnets.

[0005] The present invention will be explained in detail below. As a result of a detailed study on the effect of adding inorganic oxides to R-Fe-B permanent magnet alloys, the present inventors found that when specific amounts of zinc oxide and specific inorganic oxides are added and mixed into powder of the same alloy composition, It has been discovered that the coercive force can be increased and the squareness can be significantly improved compared to the case where zinc oxide is added alone. The basic alloy composition consists of one or more selected from rare earth elements R including Y, boron B, and the balance iron Fe, and Fe may be replaced with cobalt Co. The composition range is atomic percentage: R is 8 to 30%, preferably 12 to 18%, B is 2 to 28%, preferably 5 to 9%,
Co consists of 0 to 20% and the balance Fe. Here, the rare earth elements R include light rare earths and heavy rare earths, and include Y La, Ce, Pr, Nd, Pm, Sm, E
One or more of u, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu may be selected, but Nd and Pr are preferable. As boron B, pure boron or ferroboron is used, and as iron Fe and cobalt Co, electrolytic iron, electrolytic cobalt, etc. are used. When R is less than 8%, a high coercive force cannot be obtained, and when R exceeds 30%, the residual magnetic flux density decreases. When B is less than 2%, a high coercive force cannot be obtained, and when it exceeds 28%, the residual magnetic flux density is significantly reduced. Further, when Fe is replaced by Co, the corrosion resistance of the sintered magnet is improved, but if it exceeds 20%, high coercive force cannot be obtained.

Next, the addition of an inorganic oxide, which is the greatest feature of the present invention, is carried out by adding 0.01 to 1.0 parts by weight, preferably 0.01 parts by weight, of zinc oxide to 100 parts by weight of the basic alloy.
~0.5 parts by weight, and further 0.1 to 1.0 parts by weight, preferably 0.1 to 0.5 parts by weight of one selected from the following inorganic oxides excluding rare earth oxides, and 2 parts by weight. When more than one species is selected, the total amount may be 0.1 to 2.0 parts by weight. Al2O3, SiO2, TiO2, V
2O3, Cr2O3, MnO2, Fe2O3, CoO,
NiO, CuO2, ZnO, Ga2O3, GeO2, Z
rO2, Nb2O5, MoO3, SnO2, Sb2O5
, HfO2, Ta2O5, WO3, Bi2O3.

Since zinc oxide exists in the R-rich phase which has a great influence on the coercive force generation mechanism, even a small amount added has the effect of increasing the coercive force, but if it exceeds 1.0 parts by weight, Since the residual magnetic flux density and squareness decrease, and the effect of increasing coercive force becomes dull, it is set in the above range. In addition, the inorganic oxide added in combination with zinc oxide has the effect of suppressing the growth of crystal grains during sintering and uniformizing the crystal grain size, and ultimately precipitates compounds between boron atoms, improving squareness. Improved. Even if the amount added is small, there is a sufficient effect on improving the squareness, but if it exceeds 2.0 parts by weight, the residual magnetic flux density decreases, so the above range was set.

Furthermore, in the present invention, it has been found that the effect of adding an inorganic oxide can be improved by replacing a part of Fe in the basic alloy with the following element M. That is, the composition formula RX
BYCoZFe100-X-Y-Z-W MW, where R is a rare earth element, M is Al, Si, Ti,
V, Cr, Mn, Ni, Cu, Zn, Ga, Ge, Zr
, Nb, Mo, Sn, Sb, Hf, Ta, W, Bi, and represents one or more selected from the group consisting of 8≦X≦30, 2≦Y≦28, 0≦Z≦2 in atomic percentage.
0, rare earth iron boron alloy where 0≦W≦4.0
b) Zinc oxide 0.01 to 1.0 per 100 parts by weight
and c) 0.1 to 2.0 parts by weight of one or more selected from inorganic oxides and sintered therein. Here, if the amount of substitution of the Fe substitution element M exceeds 4.0 atomic %, the residual magnetic density decreases and the coercive force increasing effect becomes dull. The effect of adding zinc oxide and inorganic oxides shows the same tendency as the base alloy.

Next, the R-Fe-B alloy of the present invention, R-F
A method for manufacturing a magnet made of e-B-M alloy + ZnO + inorganic oxide will be described. Generally, in order to obtain excellent magnetic properties (especially coercive force and squareness), two or more stages of heat treatment are performed, but if an inorganic oxide is added as in the present invention,
It has been found that the final heat treatment alone is sufficient, and furthermore, it has been found that high magnetic properties can be obtained over a wider temperature range than usual. First, the R-Fe-B alloy or R-Fe-B-M
(Fe substitution element) The alloy raw material elements are blended, melted and
Cast to make an ingot. After coarsely pulverizing this using a brown mill, etc., it is milled using a ball mill, jet mill, etc.
Finely grind to 5 μm. This material contains ZnO with an average particle size of 0.1 to 100 μm.
and an inorganic oxide are added and mixed in a predetermined amount. The inorganic oxide may be added to and mixed with the coarse powder, and then finely ground using a ball mill. Next, the obtained alloy powder is magnetically oriented in a magnetic field of 10 kOe and compacted at a pressure of 1 ton/cm2. This molded body was placed in an argon atmosphere from 950 to 1,15.
Sinter at 0°C for 0.5-10 hours. Here, sintering in vacuum is not preferred because ZnO evaporates. Next, in order to further improve the magnetic properties, the first stage of aging treatment is heating and holding at a temperature below the sintering temperature, preferably 700 to 930°C, for 0.5 to 2 hours, and cooling at a rate of 100°C/min or more. In the second stage, the temperature may be maintained at 450 to 680°C for 0.5 to 2 hours, followed by cooling at a rate of 20°C/min or more. Here, the first stage may be omitted.

0010

[Examples] Hereinafter, embodiments of the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. (Example 1) Nd 14%, Fe 75.
Alloy Nd14Fe with 5%, Co 4%, B 6.5%
After pulverizing 75.5Co4B6.5 to 32 mesh or less in a brown mill, 0.3 parts by weight of ZnO and inorganic oxide Al2O were added to 100 parts by weight of this alloy powder.
3, SiO2, TiO2, V2O3, Cr2O3, Mn
O2, Fe2O3, CoO, NiO, CuO2, ZnO
, Ga2O3, GeO2, ZrO2, Nb2O5, Mo
O3, SnO2, Sb2O5, HfO2, Ta2O5,
The amount of each of WO3 and Bi2O3 added is 0.1~
The mixture was mixed in a range of 1.0% by weight and pulverized using a ball mill. Then, it was magnetically oriented in a magnetic field of 10 kOe, and 1To
Molding was performed at a pressure of n/cm2, and 1,
After sintering at 080℃ for 1 hour, 480-650℃
A permanent magnet was manufactured by performing one stage of heat treatment in a temperature range of . Magnetic properties of the obtained rare earth iron boron permanent magnet (Br
[KG], iHc [KOe]) were measured, and the results are shown in FIGS. 1 to 10. Note that the results of magnetic properties are the highest values obtained in the above temperature range.

(Example 2, Comparative Example) Nd in atomic percentage
14.0%, Dy 0.5%, Fe 73.5%, Co
4.0%, B 6.5%, M as Al 1.0%
, an alloy in which Fe was replaced with 0.5% Nb was coarsely ground in a Brown mill, then finely ground to 3 to 10 μm in a jet mill, and 0.5 parts by weight of ZnO and 1 part of the inorganic oxides ZrO2, Ga2O3, and Al2O3 were added. Seeds 0.
3 parts by weight were added and mixed. Following the steps of magnetic orientation, molding, and sintering under the same conditions as in Example 1, the first heat treatment was performed at 850°C for 1 hour, and after cooling to room temperature, the second heat treatment was performed on alloy No. 2. -1 was carried out at 560°C, 2-2 at 530°C, and 2-3 at 570°C for 1 hour. The measurement results of the magnetic properties of each of the produced magnets are shown in Table 1 along with the sample to which no inorganic oxide was added (comparative example alloy number 2-4).
Shown below. Table 1 also shows the results obtained by omitting the first heat treatment and performing only the second heat treatment.

0012

[Table 1]

[0013]

[Effects of the Invention] The present invention relates to a rare earth iron boron permanent magnet having a new composition and a method for manufacturing the same. A boron-based permanent magnet can be provided, and its utility value in industry is extremely high.

[Brief explanation of the drawing]

FIG. 1: Inorganic oxides (Al2O3, SiO2
, TiO2, V2O3, Cr2O3) on Br.

[Figure 2] Inorganic oxides (Al2O3, SiO2
, TiO2, V2O3, Cr2O3) on iHc.

[Figure 3] Inorganic oxides (MnO2, Fe2O3) of Example 1
, CoO, NiO, CuO2) on Br.

FIG. 4 Inorganic oxides (MnO2, Fe2O3
, CoO, NiO, CuO2) on iHc.

FIG. 5: Inorganic oxides (Ga2O3, GeO2
, ZrO2) on Br.

FIG. 6: Inorganic oxides of Example 1 (Ga2O3, GeO2
, ZrO2)) on iHc.

FIG. 7: Inorganic oxides of Example 1 (Nb2O5, MoO3
, SnO2, Sb2O5) on Br.

FIG. 8 Inorganic oxides of Example 1 (Nb2O5, MoO3
, SnO2, Sb2O5) on iHc.

FIG. 9: Inorganic oxides of Example 1 (HfO2, Ta2O5
, WO3, Bi2O3) on Br.

FIG. 10: Inorganic oxides of Example 1 (HfO2, Ta2O
5, WO3, Bi2O3) on iHc.

Claims (2)

[Claims] [Claim 1] A) Formula RX BYCoZFe100-
X-Y-Z-W MW (wherein, R is a rare earth element, M
are Al, Si, Ti, V, Cr, Mn, Ni, Cu, Z
n, Ga, Ge, Zr, Nb, Mo, Sn, Sb, Hf
, Ta, W, Bi, represents one or more elements selected from , Ta, W, Bi, 8≦X≦30, 2≦ in atomic percentage
Y≦28, 0≦Z≦20, 0≦W≦4)
b) Zinc oxide 0.01 to 1.0 parts by weight, and C) One or more selected from the following inorganic oxides 0.1 to 2. A rare earth iron boron permanent magnet characterized by a sintered body containing 0 parts by weight. Al2O3,S
iO2, TiO2, V2O3, Cr2O3, MnO2,
Fe2O3, CoO, NiO, CuO2, Ga2O3,
GeO2, ZrO2, Nb2O5, MoO3, SnO2
, Sb2O5, HfO2, Ta2O5, WO3, Bi2
O3. [Claim 2] Formula a) according to Claim 1: RX BYC
oZFe100-X-Y-Z-W When grinding a rare earth iron boron alloy represented by MW, (b) zinc oxide and (c) inorganic oxide are added, mixed and co-pulverized, sintered after orientation molding in a magnetic field, and then A method for producing a rare earth iron boron permanent magnet, which is characterized by heat treatment.