KR100213333B1 - Nd-fe-b hyperfine grain permanent magnet composition and method for manufacturing therewith - Google Patents

Abstract

(Where x, y, z, w are atomic% in the range of 0≤x≤1, 0≤y≤3, 0≤z≤1, 0≤w≤3) and are ferromagnetic phase Nd ₂ Fe ₁₄ B There is provided a composite permanent magnet composition in which Fe ₃ B and α-Fe which are weak magnetic phases are mixed.

The magnetic material of such a composition can provide the rare earth-iron permanent magnet with the maximum residual magnetization force and improved coercive force and Curie temperature.

There is also provided a method of producing a permanent magnet material having a composition as the base material.

Description

Ultrafine Granular Composite Permanent Magnet Composition and Method of Manufacturing Permanent Magnet Material Using Its Base Material

The present invention relates to a nitrogen-based (Nd) -iron (Fe) -boron (B) -based permanent magnet composition having a high energy such as high residual magnetic flux density, and a method for producing a permanent magnet based on such a composition, in more detail The present invention relates to a permanent magnet composition and a method of preparing a superfine composite composite permanent magnet having improved residual magnetization by co-compositing ferromagnetic phase Nd ₂ Fe ₁₄ B and the weak magnetic phase Fe ₃ B and α-Fe.

Commercially available permanent magnet materials include low-energy, low-cost, permanent magnets (alco-based magnets whose main component is Fe-Co-Ni-Al-Ti-Cu, iron oxide ferrite whose main component is BaO · Fe ₂ O ₃ , or SrO · 6Fe ₂ O ₃ . Magnets), rare earth-cobalt based permanent magnets (based on composition SmCo ₅ , or Sm ₂ Co ₁₇ ) and recently discovered rare earth permanent magnets (rare earth iron based permanent magnet materials, based on Nd ₂ Fe ₁₄ B composition). It is.

The Alico permanent magnet is used only for special purposes such as a speaker and a meter because of expensive manufacturing cost and complicated process, and the Sm-Co magnet is energy-efficient Higher (Tc = 700-800 ℃) permanent magnet material, but limited to high-temperature specialty products due to expensive manufacturing cost and complex manufacturing process (KJStrnat and Hoffer; USAF Materials Lab.Report AFML TR-65- 446 (1966), KJJ Bushow, RANastepad and FF Western drop: J. Appl. Phys., Vol. 40, (1969) p. 4029 and DKDas: IEEE Trans. Magn., Vol. 5, (1969) p 214 ).

Recently, cobalt-compatible rare earth-iron permanent magnets have been developed and put into practical use. A representative example thereof is a rare earth compound permanent magnet material based on ferromagnetic Nd ₂ Fe ₁₄ B.

This ferromagnetic phase always forms the ferromagnetic phase Nd ₂ Fe ₁₄ B as the main phase in the rare earth-iron-boron compound composition centered on the Nd-Fe-B ternary system, in the compositional formula of Nd _6-17 Fe _75-80 B _1-3 It is used as a strong permanent magnet material.

The rare earth-iron permanent magnet based on the Nd ₂ Fe ₁₄ B phase is replaced with Fe instead of Co, thereby reducing production cost, raw material cost and energy {(B · H) max = 25-40MGOe} and coercive force (unique coercive force: Hc = 8-20) was opened to open a new path for permanent magnets.

However, the rare earth-iron permanent magnet has limited curie temperature (Tc) of 310 ° C. or less, and thus is limited in use for high temperature. Therefore, the rare earth-iron permanent magnet is used as a bonded bonded magnet material which is formed by mixing with a resin binder. (M. Sagawa, S. Fujimura, N. Togawa, H. Yamato and Y. masuura; J. Appl. Phys., Vol. 55, (1985) p. 1964, Croat, JJ Herbst, RWLee and FEPinkerton; J. Appl, Phys., Vol. 55, (1984) p. 2078).

The rare earth-iron permanent magnet has a higher magnetic property than the material having a ferromagnetic Nd ₂ Fe ₁₄ B as a matrix structure, but the residual magnetic flux density (Br = remanance) indicating the magnetization of the magnet despite the high coercive force The problem is much lower than the theoretical one.

Accordingly, an object of the present invention is to provide a rare earth-iron permanent magnet composition which maximizes residual magnetization force and increases coercivity and curie temperature.

Another object of the present invention is to provide a method for producing a permanent magnet using a base material having the rare earth-iron permanent magnet composition.

According to one aspect of the invention A nidium-iron (cobalt, hafnium, gallium) -boron-based permanent magnet composition having a composition is provided. Wherein x, y, z and w are in the range of 0? X? 1, 0? Y? 3, 0? Z? 1, and 0? W?

According to another aspect of the present invention, (Where, x, y, z, w it is an atomic percent 0≤x≤1, 0≤y≤3, 0≤z≤1, 0≤w≤3 a range) was dissolved in the base material 10 having a composition ^5-10 Provided is a method for preparing a rare earth-iron permanent magnet material including rapidly cooling at a cooling rate of ⁶ ° C./sec to form an amorphous magnetic material, and heat treating the magnetic material at a temperature of 600˜730 ° C. for 5-20 minutes.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The permanent magnet composition according to the present invention is based on Fe (Fe), which shows the highest value of magnetization as well as the Nd ₂ Fe ₁₄ B phase exhibiting a ferromagnetic phase in the permanent magnet material using a low content of Nd. _The coexistence of ₃ B and α-Fe simultaneously creates exchange interactions to maximize residual magnetization power, and by adding a little Co, Hf, and Ga instead of Fe to increase coercivity and Curie temperature. It can be used as a permanent magnet material that requires a very high coercive force.

According to the present invention, the Nd-Fe-B ternary system (Where x, y, z and w are atomic% in the range 0 ≦ x ≦ 1, 0 ≦ y ≦ 3, 0 ≦ z ≦ 1, 0 ≦ w ≦ 3). When formed into amorphous magnetic material and heat-treated under specific conditions, crystallization and complexation of Nd ₂ Fe ₁₄ B phase having ferromagnetic characteristics and Fe ₃ B and α-Fe having extremely high saturation magnetization flows, thereby allowing proper coercive force. And a three-way mixed phase of Nd ₂ Fe ₁₄ B + Fe ₃ B + α-Fe with high magnetization. That is, excellent magnetic properties such as coercive force, residual magnetic force, maximum magnetic energy, etc. are generated by producing Nd ₂ Fe ₁₄ B having a grain size of 10-30 nm and a volume fraction of 20-30% on a matrix of Fe ₃ B, a soft magnetic phase. It is possible to obtain a permanent magnet material having a.

In addition, according to the present invention, by adding Hf and Ga to the composition, the final grain size, which is an important factor causing high residual magnetization, can be further refined to obtain a higher residual magnetization force, and by adding a little Co, the coercivity is improved. At the same time increasing the angular formation of the hysteresis loop to obtain a higher maximum magnetic energy product.

According to the invention (However, x, y, z, w are as defined above) In the magnetic material having a composition, the relative volume fraction between the ferromagnetic Nd ₂ Fe ₁₄ B phase and the weak magnetic Fe ₃ B or α-Fe phase is added to the boron ( It is determined by the amount of B), the cooling rate during quenching and subsequent heat treatment conditions.

That is, as the amount of boron (B) added increases, as the quenching speed increases, the amount of Fe ₃ B which is a weak magnetic phase increases. Excessive Fe ₃ B content causes a sharp decrease in coercive force and excessive formation of ferromagnetic Nd ₂ Fe ₁₄ B grains increases coercive force, but drastically decreases the residual magnetic flux density due to the reduction of exchange interaction, which is important in the present invention. Since it occurs, it is required to appropriately select the amount of cooling water and the cooling rate to be added.

In addition, the grain size of each of the phases present in the composition of the present invention is greatly influenced by the heat treatment conditions.

If the annealing temperature is high or the annealing time is long, the grains of the respective phases become large, resulting in a reduction of the residual magnetic flux density due to the reduction of the exchange interaction. Therefore, proper heat treatment temperature and heat treatment time are required.

In the magnetic body having the composition of the present invention, the volume ratio of the ferromagnetic Nd ₂ Fe ₁₄ B and the weak magnetic Fe ₃ B is Nd ₂ Fe ₁₄ B: Fe ₃ B = (20-30% by volume): (70-80% by volume) Is preferably.

In addition, it is preferable that the size of the preferred grain size of Nd ₂ Fe ₁₄ B is uniformly precipitated at 10-30 nm, and the grain size of Fe ₃ B and α-Fe is also preferably maintained as similar to that of Nd ₂ Fe ₁₄ B. .

On the other hand, the permanent magnet material manufacturing method according to the present invention, Where x, y, z, w are atomic%, in the range 0 ≦ x ≦ 1, 0 ≦ y ≦ 3, 0 ≦ z ≦ 1, 0 ≦ w ≦ 3. Quenching at a cooling rate of ⁵ −10 ⁶ ° C./sec to form an amorphous magnetic material, and heat treating the amorphous magnetic material at a temperature of 600˜730 ° C. for 5-20 minutes.

Dissolution of the base material having the above composition may be performed using a plasma arc melting method or the like to form an ingot after melting.

The ingot thus formed is dissolved in a quartz tube and then sprayed onto the surface of the quenching rotor to form a rapidly solidified magnetic ribbon. As described above, the quenching rate affects the volume fraction of each phase constituting the compositional magnetic compound, that is, as the cooling rate increases, Fe in the compositional magnetic body is increased.₃An increase in the amount of B produced and an excessive amount of B results in a sharp decrease in the coercive force and vice versa₂Fe₁₄B The formation of grains becomes excessive, in which case the coercivity rises, but the residual magnetic flux density decreases rapidly.

A preferred cooling rate is 10 ⁵ ~ 10 ⁶ ℃ / sec good. In order to achieve such a cooling rate, the surface speed of the cooling rotor is suitably set to 35-50 m / sec. The magnetic compound in an amorphous state prepared by quenching at the cooling rate as described above may be subjected to heat treatment under vacuum or a non-oxidizing medium component atmosphere to obtain an ultrafine granular final magnetic compound.

Since the heat treatment conditions affect the grain size of each phase as mentioned above, the preferred heat treatment temperature varies slightly depending on the amount of each sample added and the type of added element, but preferably 3-30 minutes at a temperature of 620-730 ° C. It is preferable to perform 5-20 minutes at the temperature of 620-710 degreeC.

If the cooling rate used in the present invention is too slow, not only the size of the target crystal grains from the beginning, but also the crystal grains are not uniform, so the exchange interaction force is reduced, so that if the heat treatment temperature is too high or the time is too long, the ultrafine grain composite phase is also formed. Has an adverse effect on

On the other hand, if the quenching rate is too fast, the Fe ₃ B phase or amorphous is excessively generated, so that the heat treatment time and temperature are increased, and there is a problem in practical use in terms of economy.

The ultrafine Nd ₂ Fe ₁₄ B + Fe ₃ B + (α-Fe) composite phase rare earth permanent magnets obtained by the method of the present invention as described above can be used for isotropic, resin magnets, or products that require not too high coercivity. It is economical and efficient magnetic material.

Hereinafter, embodiments of the present invention will be described.

Example 1

Rare earth-iron-boron compounds of Nd ₄ Fe _78.5 Co ₃ HfB _18.5 , Nd ₄ Fe _73.5 Co ₃ Hf _0.5 Ga _0.5 B _18.5, and Nd ₄ Fe _73.5 Co ₃ GaB _18.5 , are prepared by plasma arc dissolution process. An ingot was prepared by dissolving several times to obtain a uniform composition.

Each ingot prepared as described above was inductively dissolved in a quartz tube and sprayed onto the surface of the quenching rotor to prepare a rapidly solidified magnetic ribbon. The cooling rotor surface speed was 40 m / sec.

Subsequently, as a result of confirming the prepared magnetic compound by x-ray diffraction analysis, it was confirmed that it was composed of amorphous material. The magnetic properties were measured using a vibrating sample magnetometer and were not suitable for use as a permanent magnet material.

Therefore, each ribbon of amorphous was heat-processed in high vacuum atmosphere for 5 minutes at each temperature of 655 degreeC, 680 degreeC, and 705 degreeC. Using the prepared amorphous ribbon in the vacuum heat treatment process is difficult to control the flow of rare earth metal on the ribbon surface was cut into 4-5mm the specimen was encapsulated in a quartz tube and then subjected to a heat treatment process.

Magnetic properties were measured by applying an external magnetic field in the vertical and longitudinal directions of the ribbon surface. The magnetic measuring device was measured with a vibrating sample magnetomer at a load magnetic force of 16.4 kOe. The Curie point was determined using a thermogravimetric analyzer.

The measurement results are shown in Table 1 below.

As shown in Table 1, when cobalt (Co), hafnium (Hf), and gallium (Ga) are simultaneously added to the Nd-Fe-B composition, hafnium (Hf) and gallium (Ga) improve micronization characteristics, Cobalt (Co) improves the angular formation and coercivity greatly increases the maximum magnetic energy.

Increasing the amount of nidium from 3 atomic percent to 4 atomic percent decreased the residual magnetic flux density slightly, but the crystallization of NdFeB increased ferromagnetically and the coercivity increased significantly due to the effect of Co substituted for Fe.

In addition, the magnetic properties increase even when hafnium (Hf) and gallium (Ga) are added alone, but the ratio of hafnium (Hf) and gallium (Ga) is 1: 1 (0.5 atomic%: 0.5 atomic%). Simultaneous addition showed the best magnetic properties.

In the present invention, even when the heat treatment at a lower temperature and a shorter time than the heat treatment temperature and time of the conventional method showed better magnetic properties.

Claims (6)

Nidium-iron (cobalt, hafnium, gallium) -boron-based permanent magnet composition having a composition of Nd ₂ Fe ₁₄ B and a ferromagnetic phase of Fe ₃ B and α-Fe coexist with each other. Where x, y, z and w are in the range of 0? X? 1, 0? Y? 3, 0? Z? The composition of claim 1, wherein the grain size of Nd ₂ Fe ₁₄ B, the ferromagnetic phase, is 10-30 nm. The method according to claim 1 or 2, wherein Nd ₂ Fe ₁₄ B and Fe ₃ B is Nd ₂ Fe ₁₄ B: Fe ₃ B = (20-30% by volume): (70-80% by volume) A composition, characterized in that it is mixed in a volume ratio. Where x, y, z, w are atomic%, in the range 0 ≦ x ≦ 1, 0 ≦ y ≦ 3, 0 ≦ z ≦ 1, 0 ≦ w ≦ 3. , Quenching at a cooling rate of 10 ⁵ ~ 10 ⁶ ℃ / sec on the surface of the quenching rotor to form an amorphous magnetic material, and heat-treating the amorphous magnetic material at a temperature of 600 ~ 730 ℃ 3-30 minutes. 5. The method of claim 4, wherein the surface speed of the quench rotor is 35-50 m / sec. The method of claim 4, wherein the amorphous magnetic material is heat-treated at a temperature of 620-710 ° C. for 5-20 minutes.