A method for preparing a samarium-cobalt permanent magnet radial ring

Abstract

The application belongs to the technical field of magnetic materials, and particularly relates to a preparation method of a samarium-cobalt permanent magnetic radial ring. The preparation method comprises the following steps: (1) preparing a first alloy ingot and a second alloy ingot according to element proportioning; (2) sequentially performing mechanical crushing and airflow mill crushing on the first alloy ingot to obtain alloy powder A, and sequentially performing hydrogen crushing and airflow mill crushing on the second alloy ingot to obtain alloy powder B; (3) forming and pressing the alloy powder A to obtain a semi-ring-shaped green body A, coating or spraying the alloy powder B on the contact surface of the semi-ring-shaped green body A, pairing the semi-ring-shaped green bodies A two by two to form a ring shape, placing a metal core rod in the middle inner hole of the ring-shaped green body, and performing vacuum plastic packaging positioning on the whole to obtain a green body B; and (4) performing isostatic pressing treatment on the green body B, and performing sintering, solid solution and aging treatment to obtain the samarium-cobalt permanent magnetic radial ring.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, specifically relating to a method for preparing a samarium cobalt permanent magnet radial ring. Background Technology

[0002] With the rapid rise and development of emerging fields such as new energy vehicles, wind power generation, and artificial intelligence, rare earth permanent magnet motors have also experienced rapid development, leading to increasingly higher requirements for the core components of these motors. Samarium cobalt magnets are second-generation rare earth permanent magnets, mainly divided into 1:5 type (SmCo5) and 2:17 type (Sm2Co). 17 There are two types. Samarium cobalt permanent magnets are characterized by high magnetic properties and excellent temperature performance, with a maximum operating temperature of 250–350℃. Compared to neodymium iron boron magnets, samarium cobalt magnets are better suited for working in high-temperature environments, making them ideal for manufacturing various high-performance permanent magnet motors and applications with very complex operating environments. Furthermore, samarium cobalt magnets have extremely strong corrosion resistance, and their surface generally does not require electroplating.

[0003] Traditionally, large-size samarium cobalt radial magnetic rings can be manufactured by pressing cubic blanks followed by wire cutting, centerless grinding / external cylindrical grinding, and hole machining. This method yields radial rings with a high pass rate, but material utilization is low, resulting in significant waste at the edges and corners. Alternatively, radial cylinders can be fabricated first, and then hole machining can be performed to obtain radial rings. However, this method produces radial cylinders with significant internal stress after orientation and sintering, which is difficult to eliminate through subsequent heat treatment. During hole machining, the presence of stress greatly increases the risk of material cracking. The larger the diameter of the radial ring, the greater the internal stress, the higher the risk of hole machining cracking, and the lower the pass rate, often below 90%, or even below 50%. Directly pressing radial ring blanks and then sintering also results in significant internal stress at the pole boundaries during pressing. After sintering, the blank will crack along this location, resulting in a pass rate generally below 20%. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned technical problems by providing a method for preparing samarium cobalt permanent magnet materials, which can reduce the stress generated by pressing the ring during the orientation of the permanent magnet material and obtain samarium cobalt permanent magnet radial rings with good magnetic properties and high yield.

[0005] The present invention provides a method for preparing a samarium-cobalt permanent magnet radial ring, comprising the following steps:

[0006] (1) Prepare the first alloy ingot and the second alloy ingot according to the element ratio;

[0007] (2) The first alloy ingot is subjected to mechanical crushing and air jet milling in sequence to obtain alloy powder A, and the second alloy ingot is subjected to hydrogen crushing and air jet milling in sequence to obtain alloy powder B.

[0008] (3) Alloy powder A is molded and pressed to obtain a semi-circular green blank A, and alloy powder B is coated or sprayed on the contact surface of the semi-circular green blank A. Then, they are paired up to form a circular shape. At the same time, a metal core rod is placed in the middle inner hole of the circular shape. The whole is put into a plastic bag for vacuum sealing and positioning to obtain green blank B.

[0009] (4) The green blank B is subjected to isostatic pressing, sintering, solution treatment and aging treatment to obtain a samarium cobalt permanent magnet radial ring.

[0010] In the preparation process of the samarium cobalt permanent magnet material of the present invention, low melting point alloy powder B is coated or sprayed on the paired contact surfaces of the semi-circular green blank A. During sintering and solidification, alloy powder B melts first and acts like a binder to promote the formation of a circular shape, thus avoiding cracks in the circular samarium cobalt permanent magnet material due to excessive stress during the forming process.

[0011] Furthermore, the chemical atomic stoichiometry of the first alloy ingot is Sm 1-x Re x (Co 1-a-b-c Fe a Cu b Zr c ) z Re is one or more of Ce, Pr, Y, La, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, x ranges from 0 to 0.5, a ranges from 0.03 to a to 0.34, 0.04 to b to 0.10, 0.01 to c to 0.045, and 6.5 to z to 8.3.

[0012] Furthermore, the chemical atomic stoichiometry of the second alloy ingot is SmCu. y 0.3 <y≤0.6。

[0013] Furthermore, in step (2), the particle size of the first alloy ingot after mechanical crushing is 100-300 μm, and the particle size of alloy powder A obtained after air jet milling is 3.0-5.0 μm.

[0014] Furthermore, in step (2), the hydrogen absorption temperature during hydrogen breakdown of the second alloy ingot is 20-180℃, the hydrogen pressure is 0.1-0.2MPa, hydrogen absorption lasts for 1-5 hours, and then dehydrogenation is carried out by holding at 280-300℃ for 1-2 hours.

[0015] Furthermore, in step (2), the particle size of the second alloy ingot after hydrogen crushing is 50-200 μm, and the particle size of alloy powder B obtained after air jet milling is 3.0-5.0 μm.

[0016] Furthermore, in step (3), after the alloy powder A is shaped and pressed into a semi-circular green blank A, it is partially demagnetized, so that the surface magnetic field of the outer arc top surface of the green blank A is 20-100 Gs. The semi-circular green blank A retains a certain amount of magnetism, and the generated magnetic attraction helps the semi-circular green blank A to form a ring shape.

[0017] Furthermore, in step (3), the green body A is a radial semicircular ring with an outer diameter ≥ 40 mm, and the density of green body A is 4.2~4.5 g / cm³. 3 .

[0018] Furthermore, the molding and pressing pressure in step (3) is 15-30 MPa.

[0019] Furthermore, in step (3), the thickness of the coated or sprayed alloy powder B is 0.05 to 0.5 mm.

[0020] Furthermore, in step (3), the metal core rod is one of iron, aluminum, or copper.

[0021] Further, in step (4), the pressure of the medium static pressure treatment is 100-200 MPa, the pressure holding time is 2-8 min, and the pressure is released in two stages. The first stage of pressure release is from the highest value to 40-60 MPa, the pressure is held for 1-10 min, and then the pressure is released to atmospheric pressure.

[0022] Further, in step (4), the sintering and solution treatment is carried out at 1180-1220℃ for 30-180 min, followed by solution treatment at 1150-1195℃ for 3-10 h, then the temperature is lowered to 1140-1185℃ for 3-8 h, and finally air-cooled to room temperature.

[0023] Furthermore, in step (4), the aging treatment is isothermal aging at 800-850℃ for 10-40h, then slowly cooled to 380-450℃ at a cooling rate of 0.5-1.5℃ / min, held for 2-10h, and finally air-cooled to room temperature.

[0024] Another object of the present invention is to provide a samarium cobalt permanent magnet radial ring, which is prepared by the above-described method for preparing a samarium cobalt permanent magnet radial ring.

[0025] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0026] (1) By coating or spraying low melting point alloy powder B onto the contact surface of the semi-circular green blank A, the stress generated by pressing the ring during the orientation of the permanent magnet material can be reduced, and a samarium cobalt permanent magnet radial ring with good magnetic properties and high yield can be obtained.

[0027] (2) The low-melting-point alloy powder B melts first during sintering and solidification, and acts like a binder to promote the formation of a ring shape, thus avoiding cracks in the ring-shaped samarium cobalt permanent magnet material due to excessive stress during the forming process.

[0028] (3) The present invention adopts the radial ring direct pressing technology, and through stress relief, prepares samarium cobalt radial ring blanks with high yield, which greatly saves the use of samarium cobalt powder and greatly reduces material costs;

[0029] (4) The samarium cobalt radial ring eliminates the hole-filling process, and only internal and external grinding is required afterward. The process is simple, the cost is low, and the processing qualification rate is high. Detailed Implementation

[0030] The technical solution of the present invention will be further described and illustrated below through specific embodiments. It should be understood that the specific embodiments described herein are only for the purpose of helping to understand the present invention and are not intended to limit the present invention. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0031] Example 1

[0032] The method for preparing the samarium cobalt permanent magnet radial ring in this embodiment includes the following steps:

[0033] (1) According to Sm 0.9 Ce 0.1 (Co 0.725 Fe 0.2 Cu 0.05 Zr 0.025 ) 7.0 and SmCu 0.5 The elemental proportions were used to prepare the first alloy ingot and the second alloy ingot in the smelting furnace, respectively.

[0034] (2) The first alloy ingot is mechanically crushed to a particle size of 200 μm and then crushed by air jet mill to obtain alloy powder A with a particle size of 5.0 μm. The second alloy ingot is subjected to hydrogen absorption at a temperature of 100℃ and a hydrogen pressure of 0.1 MPa for 2 hours, and then dehydrogenated to a particle size of 200 μm by holding at 300℃ for 1 hour. Then it is further crushed by air jet mill to obtain alloy powder B with a particle size of 5.0 μm.

[0035] (3) Alloy powder A is pressed under a pressure of 20 MPa to obtain a semi-circular ring-shaped green blank A. By controlling the demagnetizing current, the surface magnetic field of the outer arc top surface of the green blank A is made to be 50 Gs. The outer diameter of the semi-circular ring-shaped green blank A is 60 mm, the inner diameter is 40 mm, and the density is 4.4 g / cm³. 3A 0.1mm thick alloy powder B is coated on the contact surface of the semi-circular green blank A, and the blanks are paired up to form a circular shape. At the same time, an aluminum rod is placed in the inner hole of the circular shape, and the whole thing is put into a plastic bag for vacuum sealing and positioning to obtain green blank B.

[0036] (4) The green blank B is isostatically pressed under a pressure of 200 MPa for 5 min. The pressure is released in two stages. The first stage of pressure release is from 200 MPa to 50 MPa and held for 5 min. Then the pressure is released to atmospheric pressure and sintered at 1220℃ for 120 min. It is then solution treated at 1180℃ for 5 h and then cooled to 1140℃ for 6 h. Finally, it isothermally aged at 850℃ for 20 h and slowly cooled to 400℃ at a cooling rate of 0.5℃ / min. After holding at 400℃ for 6 h, it is air-cooled to room temperature to obtain a samarium cobalt permanent magnet radial ring.

[0037] Example 2

[0038] The method for preparing the samarium cobalt permanent magnet radial ring in this embodiment includes the following steps:

[0039] (1) According to Sm(Co 0.66 Fe 0.25 Cu 0.06 Zr 0.03 ) 7.0 and SmCu 0.5 The elemental proportions were used to prepare the first alloy ingot and the second alloy ingot in the smelting furnace, respectively.

[0040] (2) The first alloy ingot is mechanically crushed to a particle size of 200 μm and then crushed by air jet mill to obtain alloy powder A with a particle size of 5.0 μm. The second alloy ingot is subjected to hydrogen absorption at a temperature of 100℃ and a hydrogen pressure of 0.1 MPa for 2 hours, and then dehydrogenated to a particle size of 200 μm by holding at 300℃ for 1 hour. Then it is further crushed by air jet mill to obtain alloy powder B with a particle size of 5.0 μm.

[0041] (3) Alloy powder A is pressed under a pressure of 25 MPa to obtain a semi-circular green blank A. The surface magnetic field of the outer arc top surface of the green blank A is controlled to be 80 Gs by controlling the demagnetizing current. The outer diameter of the green blank A is 50 mm, the inner diameter is 40 mm, and the density is 4.5 g / cm³. 3 A 0.3mm thick alloy powder B is coated on the contact surface of the semi-circular green blank A, and the blanks are paired up to form a circular shape. At the same time, an aluminum rod is placed in the inner hole of the circular shape, and the whole thing is put into a plastic bag for vacuum sealing and positioning to obtain green blank B.

[0042] (4) The green blank B is isostatically pressed at 150 MPa for 8 min. The pressure is released in two stages. The first stage is depressurization is from 150 MPa to 50 MPa and held for 5 min. Then the pressure is released to atmospheric pressure and sintered at 1200℃ for 120 min. It is then solution treated at 1170℃ for 5 h and then cooled to 1140℃ for 6 h. Finally, it isothermally aged at 820℃ for 20 h and slowly cooled to 400℃ at a cooling rate of 0.5℃ / min. After holding at 400℃ for 6 h, it is air-cooled to room temperature to obtain a samarium cobalt permanent magnet radial ring.

[0043] Example 3

[0044] The difference between this embodiment and embodiment 1 is only that in step (3), alloy powder A is pressed under a pressure of 20MPa to obtain a semi-circular green blank A, and the surface magnetism of the outer arc top surface of the green blank A is made to be 10Gs by controlling the demagnetizing current.

[0045] Example 4

[0046] The difference between this embodiment and embodiment 1 is only that in step (3), alloy powder A is pressed under a pressure of 20MPa to obtain a semi-circular green blank A, and the surface magnetism of the outer arc top surface of the green blank A is 150Gs by controlling the demagnetizing current.

[0047] Example 5

[0048] The only difference between this embodiment and embodiment 1 is that in step (3), a 0.01 mm thick layer of alloy powder B is coated on the contact surface of the semi-circular green blank A.

[0049] Example 6

[0050] The only difference between this embodiment and embodiment 1 is that in step (3), a 0.6 mm thick layer of alloy powder B is coated on the contact surface of the semi-circular green blank A.

[0051] Comparative Example 1

[0052] The comparative method for preparing a samarium cobalt permanent magnet radial ring includes the following steps:

[0053] (1) According to Sm 0.9 Ce 0.1 (Co 0.725 Fe 0.2 Cu 0.05 Zr 0.025 ) 7.0 The elemental proportions were used to prepare the first alloy ingot in a smelting furnace;

[0054] (2) The first alloy ingot was mechanically crushed to a particle size of 200 μm and then air jet milled to obtain alloy powder A with a particle size of 4.5 μm;

[0055] (3) Alloy powder A is pressed under 20MPa pressure to obtain a semi-circular green blank A. The outer diameter of the semi-circular green blank A is 60mm, the inner diameter is 40mm, and the surface magnetic field of the outer arc top surface is 50Gs. They are paired up in pairs to form a ring shape. At the same time, an aluminum rod is placed in the middle inner hole of the ring shape. The whole is put into a plastic bag for vacuum sealing and positioning to obtain green blank B.

[0056] (4) The green blank B is isostatically pressed at 200 MPa for 5 min. The pressure is released in two stages. The first stage is depressurization is from 200 MPa to 50 MPa and held for 5 min. Then the pressure is released to atmospheric pressure and sintered at 1220℃ for 120 min. It is then solution treated at 1180℃ for 5 h and then cooled to 1140℃ for 6 h. Finally, it isothermally aged at 850℃ for 20 h and slowly cooled to 400℃ at a cooling rate of 0.5℃ / min. After holding for 6 h, it is air-cooled to room temperature to obtain a samarium cobalt permanent magnet radial ring.

[0057] Comparative Example 2

[0058] The method for preparing the samarium cobalt permanent magnet radial ring in this embodiment includes the following steps:

[0059] (1) According to Sm 0.9 Ce 0.1 (Co 0.725 Fe 0.2 Cu 0.05 Zr 0.025 ) 7.0 and SmCu 0.5 The elemental proportions were used to prepare the first alloy ingot and the second alloy ingot in the smelting furnace, respectively.

[0060] (2) The first alloy ingot is mechanically crushed to a particle size of 200 μm and then crushed by air jet mill to obtain alloy powder A with a particle size of 5.0 μm. The second alloy ingot is subjected to hydrogen absorption at a temperature of 100℃ and a hydrogen pressure of 0.1 MPa for 2 hours, and then dehydrogenated to a particle size of 200 μm by holding at 300℃ for 1 hour. Then it is further crushed by air jet mill to obtain alloy powder B with a particle size of 5.0 μm.

[0061] (3) Alloy powder A was mixed with an equal amount of alloy powder B from Example 1, and then pressed under a pressure of 20 MPa to obtain a ring-shaped green blank A. The surface magnetic field of the outer arc top surface of the green blank A was controlled to be 50 Gs by controlling the demagnetizing current. The outer diameter of the ring-shaped green blank A was 60 mm, the inner diameter was 40 mm, and the density was 4.4 g / cm³. 3 Meanwhile, an aluminum rod is placed in the inner hole of the ring shape, and the whole thing is put into a plastic bag for vacuum sealing and positioning to obtain green blank B;

[0062] (4) The green blank B is isostatically pressed at 200 MPa for 5 min. The pressure is released in two stages. The first stage is depressurization is from 200 MPa to 50 MPa and held for 5 min. Then the pressure is released to atmospheric pressure and sintered at 1220℃ for 120 min. It is then solution treated at 1180℃ for 5 h and then cooled to 1140℃ for 6 h. Finally, it isothermally aged at 850℃ for 20 h and slowly cooled to 400℃ at a cooling rate of 0.5℃ / min. After holding for 6 h, it is air-cooled to room temperature to obtain a samarium cobalt permanent magnet radial ring.

[0063] The performance of the samarium cobalt rings obtained in the above embodiments and comparative examples was tested, and the test results are shown in Table 1 below.

[0064] Table 1 Performance data of samarium cobalt rings

[0065]

[0066]

[0067] The samarium cobalt permanent magnet radial rings obtained in Examples 1 and 2 have good magnetic properties and a high yield rate. In Example 3, by controlling the demagnetizing current, the surface magnetism on the outer arc top surface of the green blank A is too small, resulting in weak magnetic attraction. When the semi-circular green blanks A are paired, misalignment easily occurs, and the bonding force between them is weak, leading to a low yield rate. In Example 4, by controlling the demagnetizing current, the surface magnetism on the outer arc top surface of the green blank A is too large. The contact surface of the semi-circular green blank A is prone to powder adhesion, resulting in an uneven surface and weak adhesion. At the same time, it is easy to attract other ferrous components, making the corners prone to damage, resulting in a low yield rate. In Example 5, on the contact surface of the semi-circular green blank A... Applying too little alloy powder B results in poor adhesion and a low finished product yield. In Example 6, too much alloy powder B was applied to the contact surface of the semi-circular green blank A, which reduced the intrinsic coercivity of the radial ring of the samarium cobalt permanent magnet and resulted in poor magnetic properties. In Comparative Example 1, no alloy powder B was applied to the contact surface of the semi-circular green blank A, resulting in poor adhesion and a low finished product yield. In Comparative Example 2, the green blank was directly molded into a ring, which generated relatively large internal stress. This stress was difficult to eliminate through subsequent heat treatment. During the hole-making process, the presence of stress easily led to material cracking, resulting in a low finished product yield.

[0068] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the spirit of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A method for producing a Sm-Co permanent magnetic ring, characterized by comprising the steps of: The method comprises the following steps: ​ (1) preparing a first alloy ingot and a second alloy ingot according to element proportioning; (2) sequentially performing mechanical crushing and airflow mill crushing on the first alloy ingot to obtain alloy powder A, and sequentially performing hydrogen crushing and airflow mill crushing on the second alloy ingot to obtain alloy powder B; (3) forming and pressing the alloy powder A to obtain a green body A in a semicircular ring shape, coating or spraying the alloy powder B on the contact surface of the green body A in the semicircular ring shape, then pairing two by two to form a circular ring shape, placing a metal core rod in the middle inner hole of the circular ring shape, and then packaging the whole into a plastic sealing bag for vacuum plastic sealing positioning to obtain a green body B; (4) performing isostatic pressing treatment, sintering solid solution and aging treatment on the green body B to obtain a samarium-cobalt permanent magnetic radial circular ring; The chemical atomic formula of the first alloy ingot is Sm 1-x Re x (Co 1-a-b-c Fe a Cu b Zr c ) z , Re is one or more of Ce, Pr, Y, La, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, x ranges from 0 to 0.5, a ranges from 0.03 to 0.34, 0.04≤b≤0.10, 0.01≤c≤0.045, 6.5≤z≤8.3; The chemical atomic formula of the second alloy ingot is SmCu y 0.3 < y < 0.6; In step (3), after the alloy powder A is formed and pressed to obtain the green body A in the semicircular ring shape, partial demagnetization is performed, so that the surface magnetism of the outer arc top surface of the green body A is 20-100 Gs; The green body A in step (3) is a radial semicircular ring, the diameter of the outer circle is greater than or equal to 40 mm, and the density of the green body A is 4.2-4.5 g / cm 3 ; In step (3), the thickness of the alloy powder B coated or sprayed is 0.05-0.5 mm; In step (4), the sintering solid solution is sintering at 1180-1220 ℃ for 30-180 min, then solid solution at 1150-1195 ℃ for 3-10 h, cooling to 1140-1185 ℃ for heat treatment for 3-8 h, and finally air cooling to room temperature.

2. The method of producing a Sm-Co permanent magnetic radial ring according to claim 1, characterized by, In step (2), the particle size of the first alloy ingot after mechanical crushing is 100-300 μm, and the particle size of the alloy powder A obtained after airflow mill crushing is 3.0-5.0 μm.

3. The method of producing a Sm-Co permanent magnetic radial ring according to claim 1, wherein In step (2), the particle size of the second alloy ingot after hydrogen crushing is 50-200 μm, and the particle size of the alloy powder B obtained after airflow mill crushing is 3.0-5.0 μm.

4. The method of producing a Sm-Co permanent magnetic radial ring according to claim 1, wherein In step (4), the pressure of the isostatic pressing treatment is 100-200 MPa, the pressure maintaining time is 2-8 min, and the pressure is released in two stages, the first stage is released from the maximum value to 40-60 MPa, and the pressure is maintained for 1-10 min, and then the pressure is released to the atmospheric pressure.

5. A samarium-cobalt permanent magnetic radial torus, characterized by, The samarium-cobalt permanent magnetic radial circular ring is prepared by the preparation method of the samarium-cobalt permanent magnetic radial circular ring according to claim 1.

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