JPS59204210A - Isotropic permanent magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To rise the Curie point of a producted alloy, and to improve the temperature characteristic of an isotropic permanent magnet by a method wherein the isotropic permanent magnet is manufactured of a 10-25% rare earh element, 3-23% B, 50% or less Co and Fe according to sintering. CONSTITUTION:A ferro boron alloy containing electrolytic iron of 99.9% purity and 19.4% B, and the remainder consisting of impurities of Fe, Al, Si and C, and Nd of 99.7% purity or more as a rare earth element, and electrolytic Co of 99.9% purity are compounded at the prescribed ratio at first. The alloy thereof is molten according to high-frequency heating process, and casted by a water- cooled copper mold. Then it is ground rough according to a grinding stamp mill, and moreover pulverized according to a ball mill. After the impalpable powder alloy thereof is pressure molded, sintered for about 1hr at 1,000-1,200 deg.C. Accordingly, an isotropic permanent magnet consisting of Nd 15%, B 8%, Co x% (provided that x is 50 or less), Fe (77-x)% can be obtained.

Description

[Detailed description of the invention] The present invention uses iron (Fe), boron (B), and rare earth elements (R).
This paper relates to improving the temperature characteristics of permanent magnets.

In the present invention, R is used as a symbol representing a rare earth element.

Permanent magnetic materials are one of the extremely important electrical and electronic materials used in a wide range of fields, from household electrical appliances to peripheral terminals P-Z of large computers. With the recent demands for smaller size and higher efficiency of electrical and electronic equipment, permanent magnet materials are required to have higher performance.

Current representative permanent magnet materials are alnico, hard ferrite and rare earth cobalt magnets.

Recently, the raw material situation for cobalt (Co) has become unstable (C), and the demand for alnico magnets containing 20 to 30% cobalt by weight has decreased, and cheap hard ferrite, whose main component is iron oxide, is now available as a magnet material!' Rare earth cobalt magnets, on the other hand, contain 50 to 60% cobalt by weight and are very expensive because they use samarium (Sm), which is not present in rare earth ores. Because it has much higher magnetic f[- than other magnets, it has come to be used mainly in small, high-value-added magnetic circuits.

Isotropic permanent magnets generally have inferior magnetic properties compared to anisotropic permanent magnets, but are used extensively because they are not subject to restrictions on shape or magnetization direction.

Isotropic permanent magnets can be made from almost any conventional magnetic material. Shiga L7. In r-rai, alnico, manganese aluminum (MnA+) magnets, iron (Fe @ Cr-Co) magnets, there is a type of energy (BH) that has magnetic properties.
x is as low as 2MGOe at most, and the rare earth element cobal) (R-
In the case of a Co) magnet, it is 4 to 5 MGOe, which is 1/4 to 1/6 of that of an anisotropic magnet.

In Fe-R alloys, there are intermetallic compounds suitable for magnetization (1%Fe2.n2Fe17, etc. exist, but these are unsuitable for magnetization). It has been proposed to obtain an amorphous ribbon from a binary alloy containing 1% Fe by a liquid quenching method, and to magnetize the ribbon to make a magnet (Japanese Patent Laid-Open No. 57
-210934. ). In this method, (BH)max is 4
~5MGOe's Motsuka Tokurarel.

It is also possible to obtain amorphous silicon by melting and rapidly cooling Fe-B-R alloys of small size.
Although proposed by Kabacoff,
Magnetic properties at room temperature are poor, making it impractical.

Since these amorphous ribbons are ribbons with a thickness of several μm to several tens of μm, lamination or pressing after powdering is required to make them into a practical bulk, and either method has a theoretical density ratio of 6.
The magnetic resistance decreases to about 0 to 80%, and the magnetic resistance decreases, making it difficult to use as a practical magnet.

An object of the present invention is to provide a novel isotropic permanent magnet that improves the drawbacks of the conventional isotropic permanent magnet, and a method for manufacturing the same. The present invention will be explained in detail below.

The present inventors investigated sintered bodies of 1i"esR, Fe-BeR, by powder metallurgy, and found that in the R・-Fe system, l-
1c.

(JJI-1) In the FC-B-11 system, a permanent magnet with unprecedented high characteristics can be obtained within the above-mentioned specific composition range and according to a specific manufacturing method. It was done.

The present inventors have developed a permanent magnet made of a Fe-BR-based magnetically anisotropic sintered body that does not necessarily require Sm and Co, which are rare resources, and further developed a permanent magnet made of a Fe-BR-based magnetically anisotropic sintered body. We have also developed a permanent magnet made of a magnetically isotropic sintered body.

This Fe-B・R permanent magnet contains Cof, mainly uses resource-rich light rare earth elements such as neodymium (Nd) and praseodymium (Pr) as R, and F
It is superior to Zh in that it can exhibit an extremely high energy product of about gMGOe as a main component of ed.

The Fe-B-I% based Mizuku magnet has high properties at a cost 17 times lower than conventional Alnico magnets and RCo magnets, and has high cost performance compared to conventional Alnico magnets and RCo magnets. have

By the way, there is one curie of Fe, B-R system Mizuku magnet (L direction) (
Tc) is around 300°C and a maximum of 370°C. This Curie point is much lower than the Tc of about 800° C. of conventional alnico-based or R.Co-based permanent magnets.

Thus, a specific object of the present invention is to improve the temperature characteristics of an Fe-B-R based isotropic permanent magnet.

According to the present invention, by substituting a part of Fe, which is the main component of the Fe-B-R magnet, with fCo, it is possible to increase the Tc of the produced alloy and improve the temperature characteristics.

That is, the present invention has a range of R, (
However, R is at least one kind of rare earth element including Y), 3
~23% B, less than 50% C.

(excluding 000%), and the remainder Pe and unavoidable impurities, the magnetically isotropic i sintered permanent magnet is made of magnetically isotropic i sintered body permanent magnet. Co
This is an improvement to the same degree as the system magnet.

In the present invention, by containing Co,
, improves the temperature characteristics of R-based permanent magnets, and develops high magnetic properties by using light rare earth elements such as Nd and Pr, which are abundant in resources, as rare earth elements. Therefore, the permanent magnet of the present invention is a conventional R-C.

Compared to magnets, it is not only advantageous in terms of resources and cost, but also has better magnetic properties.

In general, it is recognized that when Co is contained in an Fe alloy, Tc increases or decreases as the amount of Co increases;
Replacing e with CO usually produces complex results that are difficult to predict.

C of Fe in the Fe-BR system according to the invention.

In the case of replacement by CO, as shown in FIG. 1, Tc gradually increases as the amount of CO replacement increases. In Fe-B-phosphorus alloys, a similar tendency is observed regardless of the type of R. Even a small amount of CO substitution is effective in increasing Tc.
System (77-X) Fe-BB exemplified as Fig. 1 D
-15Nd-XCo An alloy having an arbitrary Tc f of about 300 DEG C. to about 800 DEG C. can be obtained by adjusting the temperature of Tc f which is obvious from the odor. Incidentally, a similar type of alloy having such 1,000 points is not known so far.

B of the Co-based p4Fe-B-R permanent magnet of the present invention.

R2 and 0' (Fet "0) + t noa IF
j= U Th COk including'! It is basically the same as the Fe・B・R alloy.

■Figure 3 shows the relationship between LB content, iHc, and Br.

FIG. 4 shows typical examples. That is, coercive force i Hc
) In order to satisfy IK Oe, B should be 3-% or more (hereinafter, "C" indicates atomic percentage), and (BH) max
In order to achieve 2MGOe or more, at least 3KG or more of Br is required, so it is set to 23% or less. R is 1HcIK
To achieve Oe or higher, 10% or more is required, and Br is 3. I (Since it is 0 or more, it is easy to burn and is not suitable for industrial handling.
Since it is difficult to manufacture and is also expensive, it is set to 25% or less.

As R, it is possible to use a light oxidation reactor which is rich in resources, and it does not necessarily require Sm or use Sm as the main source, so the raw material is inexpensive and extremely useful.

The rare earth element R used in the isotropic permanent magnet of the present invention is
- 'Jium (Y), including light rare earth elements and heavy rare earth elements), one or more of them, preferably all light rare earth elements such as Nd and Pr, or Pr,
A mixture with Nd etc. is used. That is, 1t includes neodymium (Nd) and praseodymium (Pr).

Lanthanum (La), cerium (Ce), terbium (”
bL Dysprosium (Dy) + Holmium (HO) pErbium (Er), Europium (Eu), Samarium (Srn), Gato1 Kunium (Gd), Glomethium (
Pm) tyrium (Tm), ytterbium (Yb)
.

Included are lutetium (Lu) and yttrium (Y). As for the temperature, light rare earths are sufficient, especially Nd and P.
r is preferred. One type of reed is usually enough, but in practice, a mixture of two or more types (mitshumetal, dizim, etc.) can be used for reasons such as convenience of acquisition.
Sm, Y, La, Ce, Gd etc. are other R5 especially Nd, P
It can be used as a mixture with r, etc. Note that this pot does not need to be made of pure rare earth elements, and may contain impurities that are unavoidable in manufacturing as long as it is industrially available.

Pure boron or ferroboron can be used as boron B, and aluminum AI can be used as the impurity.

Materials containing gold such as silicon (Si) and carbon (C) can also be used.

The permanent 8 stones of the present invention are 10 to 25% R23 to 23 as described above.
%C) B, CO 50% or less, balance Fe v) Composition, coercive force i Hc≧IKOe, residual magnetic flux density B r)
The maximum energy product (BH
) rnax) 2MGOe or more'c (7) tb 7) (see Figure 3.4).

R12-20% and B5-18% each provide higher magnetic properties than 1) and (BH) may 4 MGOe within a preferable range.

The Fe-B-R based Hyaku magnet is obtained as a sintered body, but the Fe-a Coe B e R based Hyaku magnet of the present invention is made of a magnetically isotropic sintered body. That is, it can be obtained by melting and casting an alloy having the composition described above, converting it into cast alloy gold powder, and then shaping and sintering it.

Melting is performed in a vacuum or an inert gas atmosphere, and casting is performed using a mold made of copper or other metal.In this case, to prevent component segregation of the ingot alloy, a water-cooled mold may be used to speed up the cooling rate. It's wishy-washy. After cooling sufficiently, the powder is coarsely pulverized using a stamp mill or the like, and further finely pulverized using an attritor, a ball mill, etc. to a size of about 400 μm or less, preferably 1 to 100 μm.

In addition to the above-mentioned methods, methods for obtaining finely pulverized powder of Fe*B*R alloys include mechanical pulverization methods such as the spray method, physicochemical milling methods such as the reduction method, and the solution method. can be done.

This fine powder alloy was press-molded by a conventional method to obtain a molded product of approximately 9.
00-1200°C, preferably 1050-1150°C
sinter at a temperature for a predetermined period of time. By selecting sintering conditions (particularly temperature and time) so that the average crystal grain size after sintering falls within a predetermined range, an isotropic sintered magnet body with high magnetic properties can be obtained. For example, an alloy powder of 100 μm or less is molded as a starting material, and the temperature is 1050 to 1150°C for 30 minutes to
By sintering for 8 hours, a sintered body with a favorable crystal grain size can be obtained.

Incidentally, sintering is preferably carried out in a vacuum or in an inert ↑ (L gas atmosphere).For molding, use a camphor.

Paraffin, resin, binder such as ammonium chloride, zinc stearate, calcium stearate.

A lubricant or molding aid such as paraffin or resin can be used.

The CO-added Fe-B-R magnet of the present invention exhibits better temperature characteristics than the Fe-B*n three-element magnet that does not contain CO, with almost the same Br, and the same or slightly lower iHc, but C' The squareness is improved by adding o! (BH) may be equal to or greater than that. Reed,
Since Co has higher corrosion resistance than Fe, it is also possible to impart corrosion resistance by adding Co to the Fe-BR alloy.

The present invention will be explained below according to examples. However, the present invention is not limited to these examples.

Figure 1 shows typical examples of 77Fe, 8B, and 15Nd!゛System (77-X)F in which part of C is replaced with Co(X)
cX C08B15 Nd K oi""C5x't
It shows the change in Tc when changing from o to 80. This sample was prepared by the following steps.

(1) The alloy is high-frequency melted and cast in a water-cooled copper mold, and the starting material is Fe with a purity of 999, electrolytic iron, B19, 4
%? - Ferroboron alloy with gold content balance consisting of Fe and AI, Si, CC1 impurities, purity 919-f as R
/% or more (mainly other rare earth metals as impurities), and electrolytic CO with a purity of 999 was used as Co.

(2) Coarsely pulverize to 35 mesh through using a crushing stamp mill, then finely pulverize using a ball mill for 93 hours.
(3 to 10 μm) (3) Pressure mold the powder at 1.5 T/crrt (
4) Sintering at 1000-1200℃ for 1 hour in argon (Ar)
After sintering in an air stream, the crystal grain size is 5 to 30 μm, and the sintered body is left to cool. i r block cut out V
Curie point (Tc) was measured by SM as follows. That is, the temperature change of magnetization 4π■ of the sample was measured in the temperature range from 25 to 600''C, and the temperature at which 4π■ became zero was defined as Tc.

As is clear from FIG. 1, TC is C relative to Fe.

Increased rapidly due to the donation of 1.C
If o exceeds 30%, it reaches 600 ``C;

Generally, in permanent magnet materials, increasing Tc is considered to be the most important factor for reducing temperature changes in magnetic properties. To confirm this point, permanent magnet samples shown in Table 1 were prepared using the same process as the samples for Tc measurement, and the temperature characteristics of Br were measured.

The temperature change in Br was measured as follows. i.e. 25'
Magnetization curves were measured using a BH tracer at each temperature of G, 60°C, and 100°C, and the temperature changes of Br over 25-60°C and 60-100°C were averaged.

Various Fe-Co・I3. Table 1'' shows the measurement results of the temperature coefficient of Br and the magnetic properties of the R-based magnet samples and comparative examples.

It is clear from Table 1 that the temperature dependence of Br is improved by including Co in the Fe-B-R based magnet.

In order to investigate the relationship between R and B content meter iHc and Br,
Husband xNd-10Co-BB-Fe (X-0 ~
35) and 15Nd-10CO-xB-Fe systems (X-0 to 30), samples were prepared in the same manner as the above-mentioned process, and all magnetic properties were measured. The ending is 3rd and 4th
They are shown in the figure.

15 Nd- without CO, measured in the same way
The IHC curve/gland of the xB-Fe system is shown in FIG. 4 by the dotted line K.

Although the coercive force iHC decreases slightly due to Co substitution, it increases due to the improvement in the squareness of the demagnetization curve.

However, if the amount of CO replacement is large and will be published soon at 5%, iHc
1Hc) IKO as a permanent magnet material.
In order to obtain e, the Co loss should be 50% or less (see Comparative Examples J and C4 in Table 1).

Table 1 lists examples in which Nd and Pr are mainly used as R, and each exhibits high magnetic properties, and the temperature properties are further improved by replacing Fe with Co. Mixtures of two or more rare earth elements are also useful as R.

An example of an isotropic permanent magnet of the present invention (Ku 1 Thorn, Sample Black 7)
Fig. 2 shows the results of examining the relationship between iHc and average grain size using . From figure 2 i Hc n IKO
To obtain e, the average grain size after sintering must be about 1 to about 13
It needs to be 0 μm, preferably 1 to 80 μm, and preferably 3 to 30 μm.

As described above in detail, the Fe-Co5BsR isotropic permanent magnet of the present invention uses an inexpensive R raw material such as a mixture of rare earths, especially various light and heavy rare earths, such as Mitsu7yumetal and Didym. High magnetic properties can be obtained, and the CO content is less than 45 so in weight percentage (less than 50% in atomic %).
is sufficient, and Sm/Co magnets have a weight coefficient of 50 to 60 OC.
Compared to containing O, it is possible to save enough CO, and the temperature characteristics are significantly improved compared to Fe-B and phosphorus-based stones, and exhibit temperature characteristics that are sufficiently useful in practical use.

In addition to the permanent magnets of the present invention, Fe-Co.B and R, the presence of impurities unavoidable in industrial production can be tolerated, but the following development is also possible; That is, the basic composition of the present invention is 233% or less, 82
．． Contents of 5% or less, C4,O% or less, and Cu33% or less are also allowed, and are practical in this @ pronation, with a reduction in Br. C is an organic forming aid or binder;
S, P, Cu, etc. may be contained from raw materials, manufacturing processes, etc., and allowing these is advantageous for industrial manufacturing.

Furthermore, the magnet of the present invention is made of aluminum ("L titanium (Ti)").
), Bafzi'ym (V) + Riom (Cr).

Manganese (Mn), copper (Cu), zinc (Zn), zirconium (Zr), ion (Nb), -E fiber (MO).

Tantalum ('I”a), tungsten (W), tin (S
n).

Bismuth (Bi), antimony LbL spindle J, iJ
By adding the above, it becomes possible to increase the coercive force.
Further, corrosion resistance can be improved by adding nickel (N1).

As described above, the present invention has realized a permanent magnet made of a magnetically isotropic sintered body that has high residual magnetization, high coercive force, and high energy product using Fe-Co-B-n based permanent magnets and has excellent temperature characteristics. It is a complete cure that has extremely high industrial value.

[Brief explanation of drawings]

FIG. 1 shows one embodiment of the present invention.
Graph showing the relationship between c (“c, ) and Co amount (horizontal @λ
is the atomic percentage of Co), and Figure 2 shows the coercive force i Hc for one embodiment of the present invention.
A graph showing the relationship between (K Oe ) and average grain size (the horizontal axis shows the average grain size μm), and Figure 3 shows the R (Nd) content (the horizontal axis shows the atomic axis and f, Is-
(KO), 1I-Ic (KOe), Figure 4 is a graph showing the relationship between B content (horizontal axis atomic%) and B
r(KG). 111c (KOe). Applicant: Sumitomo Special Metals Co., Ltd., Patent Attorney Attorney, Kao Asahi Figure 1: Co atomic self-absorption (x%) Figure 2: Average cotton crystal size O (μm) Figure 3: Nd atomic mass (x%) Fig. 4 Fe-10co-xB-15Nd B Rinshi Hakusukeho (x%)

Claims (1)

[Scope of Claims] ■) 10 to 25% of R (R is at least one kind of rare earth element including Y), 3 to 23% of B in 6 atomic fractions
, a magnetically isotropic sintered permanent magnet consisting of 50% or less Co (excluding □% Co), and the remainder Fe and unavoidable impurities. 2) In terms of atomic head fraction, 10 to 25% R (R is at least one kind of rare earth element including Y), 3 to 23% B
, Co50% or less (excluding Co □%), and the remainder Fe and unavoidable impurities, and the magnetic isotropic sintered body permanent magnet has an orthogonal crystal grain size of about 1 to about 130 μm. . 3) In terms of atomic percentage, 10 to 25% of R (R, is Y
4), 3 to 23% of B, 50% or less of Co (excluding □% of Co), and the balance Fe and unavoidable impurities. A method for producing a magnetically isotropic sintered permanent magnet characterized by post-sintering. 4) In terms of atomic percentage, 10 to 25% of rt (R
(at least one kind of rare earth element including), 3 to 23% B, Co 50% or less (however, excluding Co □%), elemental formula of the specified ratio (however, excluding AO%, A is P 3.3% or less) ,
Magnetic isotropy consisting of 825% or less, 040% or less, Cu3.3% or less and containing two or more types of A), and the balance consisting of Fe and unavoidable impurities. Sintered permanent magnet. 5) In terms of atomic percentage, R of 10 to 25 (R is at least one kind of rare earth element including Y), B of 3 to 23
, Co50% or less (excluding oxidation, C00%), element A in the specified ratio (excluding A□%, A is P3.3% or less, 82
5% or less, C4.0% or less, Cu3.3% or less, 8 to 2
Magnetic isotropic sintering is made of a sintered body with an average crystal grain size of about 1 to about 130 μm. Solid permanent magnet. 6) In atomic percentage, 10 to 25% R (R is at least one kind of rare earth element including Y), 3 to 23% B
, Co 50% or less (however, excluding Co □%), elemental personnel in the specified section (however, excluding AO%, l'j:P 33% or less,
82.5% or less, 0.40% or less, Cu 3.3% or less, and if it contains two or more types of A, it shall be less than the maximum value of the specified ratio among the relevant elements), and the balance is Fe and unavoidable impurities. , a method for producing a magnetically isotropic sintered permanent magnet, characterized by sintering after pressure forming.