JPH051356A - Rare earth magnet material - Google Patents

Abstract

PURPOSE:To provide a rare earth bond magnet capable of securing excellent magnetic performance and temp. characteristics even when hydrogen is not contained and furthermore having sufficient heat resistance. CONSTITUTION:This is a magnet material contg. rare earth metal (R) and C, N and Fe in the ratio of 5 to 15% R, 0.1 to 20% C, 0.1 to 20% N and the balance Fe (where C+N is regulated to 5 to 25%), in which the above rare earth metal is constituted of at least one kind among Sm, Ce, Nd, Pr and S, furthermore contg. an R2 Fe17 type intermetallic compound as a main phase and in which a part of the above Fe is substituted by total <=40at.% Co according to desire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth metal-iron-carbon-nitrogen based rare earth magnet material containing an R ₂ Fe ₁₇ type compound as a main phase.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of various electronic parts and equipment, high-performance permanent magnets have been required. The Nd-Fe-B system permanent magnets developed in the 1980s have high magnetic performance and are composed of abundant and inexpensive raw materials as compared with the Sm-Co system permanent magnets developed before that. For this reason, it is being widely used industrially.

By the way, the Nd--Fe--B system permanent magnet has a low Curie point of about 300.degree. C. and thus has poor temperature characteristics, and is not suitable for use in an atmosphere of 150.degree. As a countermeasure against this, a part of Fe is replaced with Co, but the Curie point is slightly increased, but there is a problem that the coercive force is significantly reduced even with a very small amount of Co replacement. As another measure for temperature characteristics, N
It is also done to replace part of d with Dy, but Dy
Is expensive and causes a decrease in saturation magnetic flux density,
In reality, it was difficult to improve the temperature characteristics.

Therefore, it has recently been reported that a rare earth metal-iron-nitrogen-hydrogen alloy can be used as a magnet material (see, for example, Japanese Patent Application Laid-Open No. 2-57663). According to this, when nitrogen and hydrogen coexist in the alloy, Nd-F
It is said that a saturation magnetic flux density equivalent to that of an e-B system permanent magnet and a higher Curie point higher than that can be expected.

[0005]

However, according to the above rare earth metal-iron-nitrogen-hydrogen permanent magnet, hydrogen in the alloy is relatively easily released and occludes due to changes in temperature and pressure. There is a problem that the long-term stability of magnetic properties is easily impaired, and in addition, since hydrogen gas or ammonia decomposition gas, which has a risk of ignition and explosion, is handled, there is a problem in productivity.

The present invention has been made in view of the above problems, and is a rare earth magnet capable of ensuring magnetic performance equivalent to that of a Nd-Fe-B system permanent magnet and excellent temperature characteristics even without containing hydrogen. Intended to provide material.

[0007]

In order to achieve the above object, in the rare earth magnet material according to the present invention, rare earth metals (R), C, N and Fe are 5 to 15% R in atomic percentage.
-0.1 to 20% C-0.1 to 20% N-The balance Fe is contained in the ratio (however, C + N is 5 to 25%), and the rare earth metal is S.
It is characterized in that it is composed of at least one of m, Ce, Nd and Pr and contains an R ₂ Fe ₁₇ type compound as a main phase.

In the present invention, a part of Fe is C
It may be replaced with o, and in this case, the Co content is controlled to 40% or less of the total amount.

The present invention is characterized in that at least one of Sm, Ce, Nd and Pr is selected as the rare earth metal as described above, but La, La and Eu, Gd, Tb, Dy, H
At least one of o, Er, Tm, Yb and Lu can be selected together. Regarding this rare earth metal, if the content is less than 5% in atomic percentage (at%), the coercive force will decrease, and if it exceeds 15%, the saturation magnetic flux density or the residual magnetic flux density will be small, making it a practical permanent magnet. Since it is difficult, it was set to 5 to 15 at%.

Regarding C and N, the crystal magnetic anisotropy becomes small and the coercive force becomes extremely small when the total of both of them is less than 5%, while the coercive force becomes extremely small, while when they exceed 25%, the soft magnetic α-
Since the coercive force becomes smaller as Fe increases,
It was set to -20 at%. Further, if the content of C or N alone is within the range of 0.1 to 20 at%, it is effective in improving the magnetic characteristics.

Co has the effect of raising the Curie point to improve temperature characteristics and corrosion resistance, but when the total amount exceeds 40%, the magnetocrystalline anisotropy decreases and sufficient coercive force is obtained. Will not be obtained, so
It was set to 40 at% or less. In order to improve and adjust the magnetic characteristics,
Part of Fe is further divided into Ti, V, Cr, Mn, Cu and Zn.
, Zr, Nb, Mo, W, Hf, Ta, etc. can be substituted.

In order to manufacture the rare earth magnet material according to the present invention, as an example, an alloy powder composed of a rare earth metal and iron (and cobalt) is obtained, and the alloy powder is contacted with a carburizing gas and a nitriding gas at a predetermined temperature. Then, a method of invading carbon or nitrogen into the alloy can be adopted. In this case, as a method for obtaining the alloy powder, for example, a raw material in which a rare earth metal and iron (and cobalt) are mixed in a predetermined ratio is melted and cast in a high frequency induction furnace, and the obtained alloy ingot is mechanically cut by a jaw crusher or the like. Crushing method, quenching method that directly injects molten alloy into the rotating roll surface, atomizing method that injects molten alloy at high speed into gas or liquid, mechanical alloying that utilizes mutual diffusion of solid metals instead of melting The law etc. can be adopted.
Further, a method of invading carbon or nitrogen into the alloy powder is also optional, and for example, as the carburizing treatment, a general-purpose gas carburizing method using an endothermic shift gas, a carburizing method using a solid carburizing agent, an organic solvent dropping carburizing method, decompression A vacuum carburizing method that introduces a hydrocarbon-based gas into a controlled vacuum furnace can be adopted.On the other hand, as the nitriding treatment, pressurized nitrogen gas is used, or nitrogen gas and other reducing gas are used. And may be used together. It is needless to say that carbon or nitrogen may be contained in the starting alloy instead of the carburizing treatment or nitriding treatment.

The rare earth magnet material according to the present invention may be used as a bonded magnet or a sintered magnet. When used as a bonded magnet, for example, the carburized and nitrided powder described above is mixed with a thermosetting resin such as an epoxy resin or a phenol resin, compression-molded by a mold, and then at a predetermined temperature (100 to 170 ° C.). A method of curing to a magnet, a method of mixing and molding a metal such as zinc, tin or lead into the alloy powder, and then firing at a predetermined temperature (200 to 500 ° C.) to form a magnet, or a nylon resin to the alloy powder. It is possible to adopt a method in which a thermoplastic resin such as the above is mixed and injection molding is performed to obtain a magnet. On the other hand, when used as a sintered magnet, for example, a method of mixing the powder with a lubricant such as stearic acid, molding the mixture, and sintering the mixture in an inert gas or in a vacuum can be employed. In any case, an anisotropic magnet can be obtained by applying a magnetic field during molding.

[0014]

In the rare earth magnet material constructed as described above, C or N penetrates into the crystal lattice of the R ₂ Fe ₁₇ type intermetallic compound, and the saturation magnetic flux density, the Curie point and the crystal magnetic anisotropy are significantly increased. Acts to increase. Further, since the alloy does not contain hydrogen, the performance is stable for a long period of time, and since hydrogen is not handled in the manufacturing process, safety is improved.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Example 1 Samarium (Sm) having a purity of 99.9%, electrolytic iron (and electrolytic cobalt), and pig iron containing 4.3% of carbon were mixed at a predetermined ratio, charged into an alumina crucible, and charged by a high frequency induction furnace. Alloys were melted and cast into a mold to produce alloy ingots having various compositions. In many cases, segregation of the components was observed inside the alloy ingot. Therefore, the alloy ingot was heat-treated by holding it in an argon gas atmosphere at 1000 ° C for 12 hours and then rapidly cooling it. Next, this alloy ingot was subjected to a jaw crusher to roughly crush it into a size of several mm, and then further crushed by a stamp mill to obtain an alloy powder of 50 to 200 μm.

Next, the above alloy powder is put into a stainless steel small plate and charged into an electric furnace, and the atmosphere is kept under a nitrogen gas atmosphere at 5 atm.
Hold at 0 ° C for 8 hours to allow nitrogen to infiltrate, and then pulverize again with a ball mill to obtain powder samples 1 to 20 having an average particle size of 1 μm.
20 were manufactured and these were subjected to a measurement test of magnetic properties, Curie points and components. The magnetic properties were measured by packing these powder samples in a predetermined holder in a magnetic field of 15 kOe and then using a vibrating sample magnetometer (abbreviated as VSM), and the Curie point was also measured by VSM. Further, the component analysis was carried out by ICP emission spectrometry for samarium, iron and cobalt, by combustion method for carbon, and by distillation neutralization titration method for nitrogen.

The test results are shown in Tables 1 to 3. Table 1
Shows the results sorted by C and N, Table 2 shows the results sorted by Sm, and Table 3 shows the results sorted by Co. In each table, 4πIm represents the maximum magnetic flux density, iHc represents the coercive force, and Tc represents the Curie point. Since it is difficult to measure the saturation magnetic flux density, the maximum magnetic flux density was set at the maximum measured magnetic field of 20 kOe. Further, in each table, the symbol # attached to the sample number represents a comparative example.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

As is clear from Tables 1 to 3, magnet powder samples 2 to 7, 11 to 14 and 16 to 1 according to the present invention.
9 is the maximum magnetic flux density 4π Im, coercive force iHc,
A high Curie point Tc was obtained. Especially for the Curie point, it shows a high value of about 340-600 ℃, and Nd-
It was revealed that the value is sufficiently high even when compared with the Curie point of the Fe-B system permanent magnet of about 310 ° C. In addition, Comparative Example Samples 1 and 9 having a low carbon and nitrogen content, S
The coercive force iHc of the comparative sample 10 having a small amount of m is much smaller than the others, which is caused by a large amount of αFe in the alloy according to X-ray diffraction analysis. It is presumed to be a thing. Further, in Comparative Example Samples 15 and 20 containing an excessive amount of Sm or Co, the maximum magnetic flux density 4πIm also decreased at the same time as the coercive force decreased.

Example 2 Sm of 99.9% purity and 96% of Pr, Nd, Ce and D
y, electrolytic iron and pig iron were mixed and dissolved at a predetermined ratio, and subjected to nitriding treatment and ball mill grinding in the same procedure as in Example 1 to obtain an alloy powder. Next, 3% by weight of epoxy resin was mixed with this alloy powder, and compression molding was performed at a pressure of 5 Ton / cm ² while applying a magnetic field of 15 kOe, followed by curing at 150 ° C. for 1 hour to obtain magnet samples 21 to 26. Were manufactured, and these were subjected to a magnetic characteristic measurement test. The results are shown in Table 4. The magnetic characteristics were measured with a DC BH tracer after applying a pulsed magnetic field of 60 kOe. From the results shown in Table 4, in each of the magnet samples 21 to 25 according to the present invention, a high maximum magnetic flux density 4πIm and a high coercive force iHc were obtained, and it became clear that rare earth metals other than Sm can be used in combination. In the comparative sample 26, the maximum magnetic flux density and the coercive force are lowered because the total amount of the rare earth metal is excessive.

[0022]

[Table 4]

Example 3 Sm having a purity of 99.9% and electrolytic iron were mixed and dissolved at a predetermined ratio, and pulverized by the same procedure as in Example 1 to obtain 50 to 150.
An alloy powder of μm was obtained. Next, this alloy powder is put in a stainless steel small plate, charged into a vacuum furnace, and methane gas is continuously introduced into this vacuum furnace at a pressure of 0.1 Torr and kept at 1050 ° C for 2 hours to infiltrate carbon into the alloy powder. I'm sorry. Next, this powder was further charged into an autoclave, kept under a nitrogen gas atmosphere at 10 atm at 400 to 500 ° C. for 4 hours to let in nitrogen, and further pulverized by a ball mill to obtain an average particle size of 20 μm.
A powder sample of m 3 was obtained. Next, add 3% by weight of epoxy resin to this powder and apply 5 Ton while applying a magnetic field of 15 kOe.
Compression molding at a pressure of / cm ² and subsequent curing at 150 ° C. for 1 hour to produce magnet samples 31 to 34, which were subjected to measurement tests of magnetic properties, Curie points and components, and the obtained measurement test results Is shown in Table 5. From these results, the magnet samples 31 to 33 according to the present invention can obtain a high coercive force iHc, and can obtain excellent magnetic properties even by the method of continuously performing gas carburization and gas nitriding on the Sm-Fe alloy. It was confirmed that In the comparative sample 34, the maximum magnetic flux density 4πIm and the coercive force are lowered because the total amount of nitrogen is excessive.

[0024]

[Table 5]

Example 4 Sm, electrolytic iron and pig iron were mixed in a predetermined ratio and melted to produce an alloy ingot, which was then charged into a quartz tube and remelted in a high frequency furnace to form a quartz tube. The molten alloy was injected into the copper roll surface rotating at a peripheral speed of 40 m / sec from the pores in the lower part, and was rapidly cooled. The obtained quenched alloy has a thickness of about 0.05 mm,
It had a flaky shape with a width of 2 mm and a length of 10 to 50 mm. As a result of observation by an X-ray diffraction method, those crystals were isotropic and the particle size was 0.1 μm or less. Next, nitrogen was infiltrated into these thin pieces in the same manner as in Example 1 to prepare samples 41 to 44, and the samples 41 to 44 were subjected to a measurement test of components and magnetic properties. Table 6 shows
The measurement test results are shown. The measurement of the magnetic characteristics was performed using a vibrating sample magnetometer as a thin piece. From these results, the magnet samples 41 to 41 according to the present invention
44, it was revealed that a high coercive force and a Curie point were obtained.

[0026]

[Table 6]

Example 5 The magnet powder sample used in 12 of Example 1 was blended with 15% by weight of zinc powder and mixed in a ball mill, and then 150 kO.
While applying a magnetic field of e, compression molding is performed at a pressure of 4 Ton / cm ² , and subsequently heat treatment is performed in nitrogen gas at 350 to 450 ° C. for 2 hours to manufacture magnet body samples 51 to 54, and these are magnetized. It was subjected to a characteristic measurement test. Table 7 shows the results of the measurement test, and it is clear from this that good magnetic characteristics can be obtained even if a low melting point metal such as zinc is mixed with the magnet powder instead of the resin.

[0028]

[Table 6]

Example 6 The magnet powder sample used in 12 of Example 1 was added with 1.5% by weight.
After mixing with zinc stearate, the mixture was compression-molded at a pressure of 1 Ton / cm ² while applying a magnetic field of 15 kOe, and subsequently hot-pressed at 450 ° C. in nitrogen gas at a pressure of 1 Ton / cm ^2.
Sintering was carried out for 30 minutes at cm ² , and a magnet body sample was manufactured, and this was subjected to a magnetic characteristic measurement test. As a result, the maximum magnetic flux density table 4 π Im = 11230 (G) and the coercive force iHc = 9577 (O
It became clear that excellent magnetic characteristics were obtained.

[0030]

As described above in detail, according to the rare earth magnet material of the present invention, not only the magnetic characteristics equivalent to those of the Nd-Fe-B system permanent magnet can be secured, but also the temperature due to the increase of the Curie point is obtained. The properties can be significantly improved, and further, since the magnet alloy does not contain hydrogen, long-term stability of the performance can be secured. Further, since hydrogen is not handled in the manufacturing process, there is an effect that the manufacturing safety is increased.

[Table 7]

Claims (2)

[Claims] 1. Rare earth metal (R), C, N and Fe in atomic percentage of 5 to 15% R-0.1 to 20% C-0.1 to 20%
Included in the proportion of N-remainder Fe (however, C + N is 5-25
%), The rare earth metal is composed of at least one of Sm, Ce, Nd and Pr, and contains a R ₂ Fe ₁₇ type compound as a main phase. 2. A part of the Fe is 40% or less of the total amount of C.
The rare earth magnet material according to claim 1, wherein the rare earth magnet material is replaced with o.