JPS6057601A - Material of permanent magnet - Google Patents

Abstract

PURPOSE:To retain the predetermined coercive force and to increase the maximum energy product by specifying the quantity of oxygen and carbon included in MM-Sm-Pr-Co alloy of a specified composition to compose the intergranular structure of an RCo5 phase and a surface phase of an RCo7 phase. CONSTITUTION:Misch metal MM is used as a rare earth element and for the magnet material, one that has the composition of expressed by a chemical formula specified by a formula and the content of oxygen is 6,000ppm or less and that of carbon is 1,000ppm or less and the total of the contents of oxygen and carbon is 6,500ppm or less is used to perform compression molding using a pressing machine in a magnetic field followed by baking. Thus, the crystal structure composed of a surface layer of an RCo7 phase in the vicinity of a boundary of crystal grains and the structure composed of an RCo5 phase in the crystal grains are formed. Then, the material of a permanent magnet material offering IHc of 10KOe or more and (BH)max of 26MGOe or more can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement of so-called 1-5 type box earth cobalt permanent fossil consisting of rare earth elements (R) and cobalt (Co>), which is excellent in the industrial production of 81 for mass production. The present invention relates to rare earth cobalt permanent magnets that have stable magnetic properties and can be manufactured with good reproducibility.

Among the intermetallic compounds of rare earth elements and Co, RCOs
, R2Co7 and R2C017 compounds are known to be promising as permanent magnets.
1-5 type box earth Kobal 1~ magnet mainly composed of compounds,
Mainly composed of R2C0I7 compounds, some of the CO is Fe, C
Type 1-7 box soil with the general formula % (%) (where M is an added element such as Ni, Ti, Zr, or 1f) with the addition of a small amount of the fifth element. Cobalt-like magnets are used as practical permanent magnet materials with excellent magnetic properties.
It is called industrial production.

Currently, rare earth elements 1, 1. ．． 1J Tonto 3n; limited to 1-
The type 5 mineral has a binary composition of Sl[1-GO and contains metal,
At mass production level, coercive force] 1-4 c = 10-4
0K Os 1 Maximum magnetic energy (B H) n[
ax = 15-24M Shows the magnetic properties of GOe. Furthermore, the type 1-7 treated stone has a multi-component alloy composition mainly composed of 3m-Go-Fe-Cu, and has a coercive force 1 U lower than that of the type 1-5 treated stone, +1-1c = ! +-8KO
However, (B H) l'l+ax is large, and exhibits a characteristic of 20 to 281 νi G Oe at the mass production level.

By the way, the permissible humidity range required for such practical permanent magnets is -40°C to 80°C for normal acoustic two-rotation devices, and even wider for special electronic equipment, from -60°C to -60°C. In this case, 1-7 type rare earth magnets with low coercive force cannot be used, and even though the energy product is low, the coercive force is large and 250°C.
Only type 1-5 rare earth magnets are used, which can be used stably up to a high temperature range of around 50℃, and type 1-7 rare earth magnets have inferior mechanical properties compared to type 1 frosted earth magnets. In terms of productivity and product yield, the 1-5 type rare earth magnet It's far superior.

Therefore, the maximum human energy product of the 1-5 type box-earth cobalt magnet, which has a large coercive force and excellent thermal stability, can be improved while maintaining the conventional coercive force. There was a strong demand for permanent magnet 4J materials, and various attempts were made, or only in the laboratory. I'm not alone.

That is, currently, the highest magnetic properties of 1-5 type rare earth magnets are Sm (0,41) Pr (0,59n Co (4
, 2) (molar ratio) in the alloy J3, Br = +0.1KG, B Hc =, 10.1KO
eIHc = i6.3KOa, (B H) may =
26. OM GOe has only been obtained in the laboratory, and the practical permanent magnet 4A material on a mass production scale is 1',
not present. This is because the surficial earth elements have a close relationship with oxygen and nitrogen.
The force is very strong, and especially the affinity with M is stronger than l'ip, /V, which is effective as a deoxidizing agent in the 7th row steelmaking, and 7, -mede, which is almost as strong as Sshi<Ca. The affinity of Pr for oxygen, which is used to replace S+n to improve magnetic properties, is stronger than SmJ:, and the oxidation during the manufacturing process of the alloy with the above composition is severe, so the alloy composition to obtain the best properties is The range and optimum heat treatment conditions are also strict, and stable manufacturing conditions have not been found, making it difficult to reexamine magnetic properties.

This invention provides a 1-5 type box earth cobalt magnet with excellent mechanical properties, extremely high coercive force, and excellent thermal stability. Permanently improved 16 stones + A 'AQ while maintaining
! It is an object.

That is, in this invention, the composition is represented by the following chemical formula,
Oxygen content is less than Gooop 4, carbon content is iooo
ppm or less, the total amount of oxygen and carbon is 6500ppn
Below + and near the grain boundaries, the surface layer of ReO2 phase and inside the grains have a crystal structure consisting of RCo5 phase, +
1-1c more than 10KOe''2, (B l-1> max
Permanent magnetic material with 26 MGOe or more.

MMA Sn+ B Pr c Co Z However, A: mole of MM m
=1 0.01≦A≦0.05 0.43≦8≦0.57 0.43≦C≦0. ! i7 0.7≦c/e≦1.3 4.3≦Z≦5.0.

This invention was developed as a result of examining various problems caused by conventional MM
-3m -Pr -Qo Quaternary composition alloy d3ite, effective use of Mitshu metal (MrVl) as a rare earth element as a small amount of substitution element, specifying the 41゜4 composition ratio of MM, Sm, pr, and C acid It has been discovered that by determining the limit value of ff1iiid3 and the amount of carbon contained, it is possible to stably obtain a permanent magnet material with high magnetic properties within the specifications.

This invention is characterized by replacing 3m, J, and pr with MM.
．． ) Sm (0,51
) Pr (0,49) Co (4,45) is the basic component of the alloy J3, and the sintering temperature of three types of magnet alloys in which the molar amount of IDr is kept constant and a part of Sil + is replaced with MM. The above-mentioned 3m
-pr -co MM is better than ternary composition magnet alloy.
On the right, MM-3m-Pr-Co4 which is within the scope of the present invention
It is clear that the original composition magnet alloy can obtain a higher sintered density over a wider range of sintering temperatures, expands the heat treatment temperature range, and stably obtains high magnetic properties.

The reason why this MM gold content is effective is that Sm・l'Pr and Co
Compounds with MM and (,0) form more compounds with low melting points than compounds with It is thought that the sinterability has improved, making it possible to expand the heat treatment temperature range and achieve high magnetic properties.

In addition, as a result of detailed investigation into the relationship between the microcrystalline structure, crystal drawing, and magnetic properties of the magnetic alloy of this invention using a high-intensity X-ray diffraction device and a scanning electron microscope, we found that the permanent As described below, impurities such as rare earth oxides (R203) and rare earth carbides (RC2) aggregate near the boundaries of the individual crystal grains that make up the magnet, and as a result, the individual crystal grains become crystallized from the vicinity of the grain boundaries. towards the center of the grain, especially in the region close to the grain boundary,
The amount of rare earth elements (R) decreases, and a surface stone that migrates to the COric 11 side structure is formed. However, the 4743 blue in the surface layer near the grain boundaries within each grain is R2C.
It has become clear that high magnetic properties can be obtained only when the magnet has an RCOZ crystal structure, which is a disordered phase of the 017 crystal structure, and the grains are composed of an RCOs phase.

The reasons for limiting the components in this invention will be explained below.

In this invention, MM is an IIGJ acid agent for normal steelmaking or a mixed rare earth metal added to improve workability.
The purity of all rare earth elements in it is over 98wt%, Fe 1
1Vt% or less, t'b, Nc15. It is a quality raw material that can freely contain J and SL of 1% or less. For example, the 4i1 composition ratio of the total rare earth elements in MM is Co4/l ~ 55wt%.
, La20-35wt%, Na10-20wt%, Pr
3.-7wt%, remaining rare earth elements 1 to 6 such as 8111
It consists of wt%.

Molar ratio (A) of MM among rare earth elements in this invention
Assuming o, oi-0.05, lζrizan is less than 0.01, which results in high magnetic properties, as is clear from the relationship between sintering temperature and sintering density in Figure 1, for example. The optimum sintering temperature range will not expand, and stable mass production will not be possible.
Moreover, if it exceeds 0.05, the ol-1c characteristic of 101<Oe or more, which can be seen from the relationship between the sintering temperature and 5l-1c in FIG. 1, will no longer be obtained.

The reason why the molar ratio (l]) of 3m is 0.43 □-〇;57 is that if it is less than 0.43, +1-1c will be less than 10 KOe, and if it exceeds 0.57, +1-1c will be more than 10 KOe. However, (, B I-1) max is 26MGOe
This is because the following is true.

In addition, the reason why the molar ratio (c) of pr is set to 0.43 to 0.57 is because 13r is low when it is less than 0.43, so (BH)ma
x also becomes less than 26MGOe, and when it exceeds 0.57, tree 4
This is because the oxidation of the base alloy is so severe that it cannot be used as a material for practical permanent magnets.

In this invention, when the molar ratio (C/B) of l)r and 3m is less than 0.7 and exceeds 1.3, (BH)max
is less than 26 MGOe, +Na is less than 10 KOe,
Since high magnetic properties cannot be obtained, it is set to 0.7-1.3.

In addition, the reason why the molar ratio (z) of CO was set to 4.3□ to 5.0 is because if it is less than 4.3, RCOs, which is the essence of the water-based alloy composition,
phase becomes 60% or less, RzC (17 phase becomes 40% or more, and finally IHc > 10KOe, (B1-I)
This is because the characteristics of maX > 26M G Oe are stable and -C cannot be obtained, and if it exceeds 5.0, RzCO + 7 phase, which is harmful to the magnetic properties in J3 in the water-based magnet alloy, is generated and cannot be used as a practical permanent magnet. This is because there is no T.

In general, type 1-5 rare earth magnets are manufactured through the following steps: melting, crushing, press forming, sintering, and 11,1 effect treatment of an alloy with a predetermined composition, but rare earth elements are easily oxidized during the process. , easily generates RzO3 oxide, and also easily generates RC2 carbide by residual organic solvents such as hexadi-1-toluene used during pulverization and binders such as paraffin and camphor used to improve press formability. Ru.

If these oxides and carbides exist in the crystal grains of type 1-5 rare earth magnets, they will have a very negative effect on the magnetic properties, so it is originally better not to contain any of these compounds to improve the magnetic properties. is also preferable, but as mentioned above, the C-right is unavoidable in terms of manufacturing.

Therefore, in this invention, the oxygen content and carbon content are specified, and the oxygen content is 6000 ppm.
If the oxygen content exceeds 600ppm, the coercive force will gradually decrease to less than 7KOθ due to excessive rare earth oxides being incorporated in the crystal grains. If so, excessive rare earth carbides will be contained, which will deteriorate the magnetic properties more than rare earth oxides, and (B Ll ) maX will be less than 10 M G Oe. Therefore, the carbon content is specified to be less than 11,000 pp. do.

In addition, oxygen and FA cables are each a cause of deterioration of magnetic properties, and if the sum of both exceeds 6500 ppm, rl-
1c is 10KOe or less, (B l-l) max is 2
Since it is less than 6MGOe, the content of oxygen and carbon; il'
The total sum of i is 6500 ppm or less.

Examples will be described below.

Example 1 (e4e, swt%, r30,8\V(%, lV+di
! Remaining rare earth elements such as iwt%, p, 4wt%, Sm2wt%d5 and Fellvt% or less, Mg, /V
, SL 1% or less (f;
(0,02) Sm (0,49)Pr (0,49
) Co, (4,45)h2:MM (0,04)
Sm (0,47>Pr (0,49) Co (4
,45) Nc, 3: Sm (0,51) Pr (
0,49) Co (4,45) No 4:MM (0,025) Sm (0,485
)Pr(0,49)Co(4,44(1)) Four types of magnetic alloys were obtained.Nad3 and positive3 are comparative examples.

The alloy after melting is coarsely pulverized to 500 grains in a stamp mill in an argon atmosphere, and then processed into organic powder. A fine powder with an average particle size of 3 to 5 μm was obtained by ball milling in 8 medium.

This fine powder was applied using a magnetic field width press (shallow, 10KOθ
compression molding with a magnetic field of 1 t4 and a pressure of 1 t4. The obtained molded body was heated to various S' temperatures of 1100°C to 1140°C.
The sintered permanent magnet according to the present invention and the ternary sintered magnet for comparison were sintered for a time and then aged at 900°C for 2 hours. 3 Sintered magnet odor-(, Burn-1 [,
The results of measuring BHc, (BH)max, and density when sintered at various temperatures are shown in the graph of FIG.

First, looking at the relationship between sintering temperature, sintered density, and (B
As the temperature increases from 1,100°C to 1,140°C, the density (BH) max increases linearly, but BHC already shows a decreasing tendency above 1,120'C, making it difficult for industrial use. It can be seen that it is difficult to set the optimum sintering temperature for these properties.

In contrast, Ni1 (
Plotted with O mark), the sintering temperature ranges from 1100℃ to 1140℃.
5f-1c, f2 compaction density over the entire temperature range.

(BH) maX is constant and shows a high value,
It can be seen that high magnetic properties can be stably obtained.

N; J5 and 'Fkh' 2 are plotted with 0 marks.

Next, as the magnetic properties and mechanical properties of the sintered magnet with a ratio of 4 according to the present invention, bending strength, compressive elasticity, and tensile strength were measured, and the following excellent properties were obtained. The oxygen content of the sintered body is 5400 ppm, and the carbon content is 730 ppm.
It was ppm.

Sr -10.8KG, a Hc ”10.6KOe
ll-jc'= 17.2KOe, (131-1)
max=28.51 VI G Oe bending strength: 18
, 2 to 4, Compressive strength: 120kg4, Tensile strength:
3.9 to 94 Also, for comparison, as an example of a 1-7 type rare earth Kobal 1 ~ magnet, Sm (Go (0,64 N Fa (018) N1 (
0,08) Cu (0,1>) 7.0 Magnet alloy was also subjected to similar measurements, and the following characteristic value was 137. Therefore, as a result, it is clear that the mechanical properties of the magnet of the present invention are inadequate.

Br = 10.6KG, e 1-1c = 5.9K
Oe+ 1-lc = 6.0KOe, ([3H) 1
I121X -27,0fvl G Oe bending strength:
14, 7 k'j 4F, compressive strength: 3 units of 801a,
Tensile strength: 3.4 to 4 Example 2 Ce47.5wt%, r31.0wt%, N:113,
8W[%, Pr4 wt%, remaining rare earth elements such as Sm 2,5wl:%1ll-1i and Feiw(%T”
, Mg, #, SL 1% or less] 411″I component, and 3m with a purity of 99.9% or more,
pr.

Using raw material powders of
04) Sm(0,96-x)pr(x)C
An alloy according to the invention was obtained having the following composition: o'(4,45), X-0,32-0.58.

The alloy after melting was processed by a stamp mill in argon for 50 min.
It was ground to 0JJm, and then ball milled in a low solvent to produce a fine powder with an average particle size of 3 to 5ρ. :l.

This fine powder was compression-molded in a magnetic field press machine under a magnetic field of 10 KOe and a pressure of 1. The obtained compact was sintered for 1 hour in a 1120°C sintering oven, and then sintered at 900°C for 2[1? The sintered permanent magnet according to the present invention is produced by applying 11:4 effect treatment between j and 11;

e Ll, c, ([31-
1) max L! '3 and the sintered density are determined, Pr
The relationship with the molar ratio of /SD+ is not shown in FIG.

As is clear from FIG. 2, it can be seen that a high maximum energy product of 26 M G 00 or more and eHc of 10 KOe or more are concentrated when the value of Pr /Sm is around 1.

Dokuni, MM (0,04) 3m < 0.48)
The Kaisei magnet Pr(0'i3)Co(4,4!l) has a mass of 131" 1 (1,7KG, [41-
1c ・□ 10. [1KOe+Llc=18.5
KOe, (131-1) +:+ax =27.8MG
The oxygen content of the burnt porcelain is 480011+, and the charcoal content is 7.
/1oppnl-1” 89 Tsunoko.

It is obvious from the fire heat 15 that J, sea urchin, mechanical q, 'I'J's failure, and i'A: 14fi force or human body and λj)
Stable η to the broken 1 ze office 1 soil ode to Kobal 1 (J3 in the ox Iko, 1:); follow the "magnetic") this b throat IQI
After AF, the second one (Song J), the energy of no human beings was improved meekly, and the permanent magnet 1 and 1 stable!
'J JIl! Sex J, <(1) I can see that it's sad.

[Brief explanation of the drawing]

FIG. 1 shows the magnet [1l-1c,
(B H) l1laX J3 hiN2t+'i
Density ILL k Measurement * L/, U'A km H IJI Which relationship C'' outside P Graph d9, Figure 912 shows the sintered magnet according to the present invention, [1l-IC1([3H) ma
This is a graph in which the sintered density was measured and expressed in relation to the molar ratio of Pr/Sm. Figure 1) Long and warm thighs ('C) Figure 2 P! /Sm mole this

Claims (1)

[Claims] 1. The composition is represented by the following chemical formula, and the oxygen-containing mother is 600
oppm or less, carbon content is 11,000 ppm or less, the sum of oxygen amount and carbon amount is 6,500 ppm or less, and near the grain boundaries, the surface layer of the RCO7 phase and inside the grains are F<C
The crystal IlI consisting of the Os phase is placed on the right, and +1-1c is 1
0KOe or more, (B l-1> max to 26MGOe
Permanent magnet material γ81,1M characterized by having the following:
MA 3m B Prc Coz However, A: -El amount of MIVI, B: molar amount of 5T11, c:
Molar amount of Pr, Z: molar ratio of CO to rare earth element A+B+C=1 0.01≦A≦0.05 0.43; o≦0.57 0.43≦C≦0.57 0.7≦ C/B≦1.3 4.3≦7≦5.0