A method for preparing a radial samarium-cobalt ring

Abstract

The application belongs to the technical field of magnetic materials, and particularly relates to a preparation method of a radial Sm-Co 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 ball mill crushing on the second alloy ingot to obtain alloy powder B; (3) mixing the alloy powder A and the alloy powder B, then performing forming and pressing to obtain a green body A, and performing hole sleeving processing on the middle part to obtain a green body B; and (4) inserting a metal rod into the inner hole of the green body B, and performing isostatic pressing treatment, sintering solid solution and aging treatment to obtain the radial Sm-Co ring. The alloy powder B is mixed with the alloy powder A to obtain the green body A, so that the density of the Sm-Co cylindrical green body A can be improved, the pressure required during the forming and pressing can be reduced, the cracking of the radial Sm-Co ring can be reduced, and the radial Sm-Co ring with good magnetic performance can be obtained.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, specifically relating to a method for preparing radial samarium cobalt rings. 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 high-temperature environments, making them ideal for manufacturing various high-performance permanent magnet motors and applications with highly 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 produces radial rings with a high yield rate, but the material utilization rate is low, and there is significant waste at the edges and corners. Alternatively, radial cylinders can be fabricated first, and then hole machining can be performed on these cylinders to obtain radial rings. However, the radial cylinders prepared by this method develop significant internal stress after orientation and sintering, and this stress is difficult to eliminate through subsequent heat treatment. During the hole machining process, 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 yield rate. Often, the yield rate is less than 90%, or even below 50%. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned technical problems by providing a method for preparing radial samarium cobalt rings, which can reduce cracking of radial samarium cobalt rings and obtain radial samarium cobalt rings with good magnetic properties.

[0005] The present invention provides a method for preparing a radial samarium cobalt 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 ball milling in sequence to obtain alloy powder B.

[0008] (3) After mixing alloy powder A and alloy powder B, the mixture is molded and pressed to obtain green blank A, and the middle part is machined to obtain green blank B.

[0009] (4) Insert the metal rod into the inner hole of the green blank B, and obtain a radial samarium cobalt ring by isostatic pressing, sintering and solution treatment and aging treatment.

[0010] 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 0.8, a ranges from 0.03 to a to 0.35, 0.04 to b to 0.15, 0.01 to c to 0.05, and 6.5 to z to 8.3.

[0011] Furthermore, the chemical atomic stoichiometry of the second alloy ingot is SmCo. y 0.45 <y≤0.6。

[0012] Air jet milling has advantages such as high efficiency and speed. Therefore, the first alloy ingot of this invention uses mechanical crushing and air jet milling to prepare alloy powder A. The first alloy ingot is a 2:17 type samarium cobalt material, whose grain boundary phases are mainly 1:5 and 2:7 phases. The strength of the grain boundary phases is stronger than that of the main phases, making the material prone to transgranular fracture. At the same time, because air jet milling involves airflow driving particles to directly collide and break them, the broken powder particles are disc-shaped, and these disc-shaped powder particles are not easy to orient. The second alloy ingot uses a combination of hydrogen crushing and ball milling to prepare granular alloy powder B. Since the second alloy ingot is a 1:5 type samarium cobalt material, the strength of the main phase is stronger than that of the grain boundaries, making it easier to obtain intergranular fracture. Adding a small amount of alloy powder B can increase the density of the samarium cobalt cylindrical green blank A, while reducing the pressure required for molding and pressing, thus reducing the risk of cracking caused by excessive pressure and stress in the samarium cobalt cylindrical green blank A.

[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 is 20–180°C, the hydrogen pressure is 0.1–0.2 MPa, the hydrogen absorption time is 1–5 h, and then the temperature is maintained at 280–300°C for 1–2 h.

[0015] Furthermore, in step (2), the particle size of the second alloy after hydrogen crushing is 100-300 μm, and the particle size of alloy powder B obtained after ball milling is 3.5-4.5 μm.

[0016] Furthermore, in step (3), the mass ratio of alloy powder A to alloy powder B is 90:10 to 99:1. When alloy powder A and alloy powder B are mixed, the density is relatively low, and cracks are easily generated due to excessive stress during molding and pressing. When the density is high, the molding and pressing effect is poor, and the mechanical and magnetic properties of the samarium cobalt ring are poor.

[0017] Furthermore, the pressing pressure in step (3) is 15-20 MPa. If the pressing pressure is too low, it is easy to cause chipping or cracking due to vibration and impact during the purging process. If the pressing pressure is too high, it will make purging difficult and may cause problems such as heat generation and oxidation during the purging process.

[0018] Furthermore, in step (3), the green body A is a radial cylinder with an outer diameter ≥ 40 mm and a density of 4.8~5.5 g / cm³. 3 Due to its low filling density and difficulty in powder rotation, the green compact density of typical samarium-cobalt materials is generally below 4.5 g / cm³. 3 Only by increasing the pressing pressure significantly can a value of 5.0 g / cm³ be obtained. 3 The above-mentioned green blanks require high-performance pressing equipment, and such high pressing pressure results in significant elastic aftereffects. Once the pressure is removed, the green blanks will undergo large deformations due to these aftereffects, leading to cracking. This invention uses a suitable pressing pressure to obtain radial rings with high density, ultimately yielding radial magnetic rings with excellent magnetic properties.

[0019] Furthermore, in step (3), the diameter of the sleeve hole is 30-60 mm, the rotation speed of the sleeve head is 100-500 rpm / min, the sleeve hole is machined from bottom to top, and a magnet is installed under the sleeve head. Machined from bottom to top, which facilitates chip removal from the green blank, and the magnet under the sleeve head facilitates the adsorption and removal of magnetic powder.

[0020] Furthermore, in step (4), the metal 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 10-30 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 radial samarium cobalt ring, which is prepared by the above-described method for preparing radial samarium cobalt rings.

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

[0026] (1) By using different crushing methods to make alloy powder of different components, a small amount of alloy powder B is mixed with alloy powder A to obtain green blank A, which can increase the density of samarium cobalt cylindrical green blank A, while reducing the pressure required during molding and pressing, reducing radial samarium cobalt ring cracking, and obtaining radial samarium cobalt ring with good magnetic properties.

[0027] (2) The present invention advances the hole-punching step to the forming stage, avoiding the hole-punching process in the blank stage, which greatly improves the yield and material yield of the radial ring.

[0028] (3) The density of the green body after molding is not particularly high. The powder generated during the hole-making process can be used directly after sieving, which greatly reduces the material cost. Detailed Implementation

[0029] 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.

[0030] Example 1

[0031] The method for preparing radial samarium cobalt rings in this embodiment is characterized by comprising the following steps:

[0032] (1) According to the element ratio Sm 0.92 Ce 0.08 (Co 0.70 Fe 0.22 Cu 0.05 Zr 0.03 ) 7.7 and SmCo0.5 The first alloy ingot and the second alloy ingot were prepared in a smelting furnace, respectively.

[0033] (2) The first alloy ingot was mechanically crushed to a particle size of 200 μm and then crushed by air jet milling to obtain alloy powder A with a particle size of 5.0 μm. The second alloy ingot was subjected to hydrogen absorption at a hydrogen absorption temperature of 100℃ and a hydrogen pressure of 0.1 MPa for 2 h, and then dehydrogenated to a particle size of 200 μm by holding at 300℃ for 1.5 h. The ingot was further crushed by ball milling to obtain alloy powder B with a particle size of 4.0 μm.

[0034] (3) Alloy powder A and alloy powder B are mixed at a mass ratio of 95:5 and then pressed under a pressure of 16 MPa to obtain a radial cylindrical green blank A with an outer diameter of 60 mm and a density of 5.2 g / cm³. 3 The blank B is obtained by machining a hole in the middle part. The diameter of the hole is 40mm and the rotation speed of the hole is 300rpm / min. The hole is machined from bottom to top to facilitate chip removal of the blank. At the same time, a magnet is installed under the hole to facilitate the removal of magnetic powder.

[0035] (4) Insert the aluminum rod into the inner hole of the blank B and hold it under pressure of 150MPa for 5 minutes for isostatic pressing. Depressurize in two stages. In the first stage, depressurize from 150MPa to 20MPa and hold for 5 minutes. Then depressurize to atmospheric pressure and sinter at 1200℃ for 100 minutes. Then, solidify at 1180℃ for 5 hours and then heat treat at 1150℃ for 5 hours. Then, isothermally age the magnet after solidification treatment at 800℃ for 30 hours. Then, slowly cool it to 400℃ at a cooling rate of 0.5℃ / min and hold for 5 hours. Finally, air cool it to room temperature to obtain a radial samarium cobalt ring.

[0036] Example 2

[0037] The method for preparing radial samarium cobalt rings in this embodiment is characterized by comprising the following steps:

[0038] (1) According to the elemental ratio Sm(Co) 0.71 Fe 0.2 Cu 0.06 Zr 0.03 ) 7.7 and SmCo 0.6 Prepare a first alloy ingot and a second alloy ingot respectively;

[0039] (2) The first alloy ingot was mechanically crushed to a particle size of 200 μm and then crushed by air jet milling to obtain alloy powder A with a particle size of 5.0 μm. The second alloy ingot was subjected to hydrogen absorption at a hydrogen absorption temperature of 100℃ and a hydrogen pressure of 0.1 MPa for 2 h, and then dehydrogenated to a particle size of 200 μm by holding at 300℃ for 1.5 h. The ingot was further crushed by ball milling to obtain alloy powder B with a particle size of 4.0 μm.

[0040] (3) Alloy powder A and alloy powder B are mixed at a mass ratio of 97:3 and then pressed under a pressure of 18 MPa to obtain a radial cylindrical green blank A with an outer diameter of 80 mm and a density of 5.0 g / cm³. 3 The blank B is obtained by machining a hole in the middle part. The diameter of the hole is 50mm and the rotation speed of the hole is 350rpm / min. The hole is machined from bottom to top to facilitate chip removal from the blank. At the same time, a magnet is installed under the hole to facilitate the removal of magnetic powder.

[0041] (4) Insert the aluminum rod into the inner hole of the blank B and hold it under pressure of 180MPa for 5 minutes for isostatic pressing. Depressurize in two stages. In the first stage, depressurize from 180MPa to 20MPa and hold for 3 minutes. Then depressurize to atmospheric pressure and sinter at 1200℃ for 150 minutes. Then, solidify at 1180℃ for 6 hours and then heat treat at 1150℃ for 5 hours. Then, isothermally age the magnet after solidification treatment at 800℃ for 25 hours. Then, slowly cool it to 400℃ at a cooling rate of 0.5℃ / min and hold for 8 hours. Finally, air cool it to room temperature to obtain a radial samarium cobalt ring.

[0042] Example 3

[0043] The only difference between this embodiment and embodiment 1 is that in step (3), alloy powder A and alloy powder B are mixed at a mass ratio of 98:2.

[0044] Example 4

[0045] The only difference between this embodiment and embodiment 1 is that in step (3), alloy powder A and alloy powder B are mixed at a mass ratio of 85:15.

[0046] Comparative Example 1

[0047] The method for preparing the comparative samarium-cobalt ring is characterized by comprising the following steps:

[0048] (1) According to the element ratio Sm 0.92 Ce 0.08 (Co 0.77 Fe 0.22 Cu 0.05 Zr 0.03 ) 7.7 Preparation of the first alloy ingot;

[0049] (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 5.0 μm;

[0050] (3) Alloy powder A is formed and pressed under a pressure of 40 MPa to obtain a radial cylindrical green blank A with an outer diameter of 60 mm and a density of 4.2 g / cm³. 3The blank B is obtained by machining a hole in the middle part. The diameter of the hole is 40mm and the rotation speed of the hole is 300rpm / min. The hole is machined from bottom to top to facilitate chip removal of the blank. At the same time, a magnet is installed under the hole to facilitate the removal of magnetic powder.

[0051] (4) Insert the aluminum rod into the inner hole of the blank B and hold it under pressure of 150MPa for 5 minutes for isostatic pressing. Depressurize in two stages. In the first stage, depressurize from 150MPa to 20MPa and hold for 5 minutes. Then depressurize to atmospheric pressure and sinter at 1200℃ for 100 minutes. Then, solidify at 1180℃ for 5 hours and then heat treat at 1150℃ for 5 hours. Then, isothermally age the magnet after solidification treatment at 800℃ for 30 hours. Then, slowly cool it to 400℃ at a cooling rate of 0.5℃ / min and hold for 5 hours. Finally, air cool it to room temperature to obtain a radial samarium cobalt ring.

[0052] Comparative Example 2

[0053] The method for preparing the comparative samarium-cobalt ring is characterized by comprising the following steps:

[0054] (1) According to the element ratio Sm 0.92 Ce 0.08 (Co 0.70 Fe 0.22 Cu 0.05 Zr 0.03 ) 7.7 and SmCo 0.5 The first alloy ingot and the second alloy ingot were prepared in a smelting furnace, respectively.

[0055] (2) The first alloy ingot was mechanically crushed to a particle size of 200 μm and then crushed by air jet milling to obtain alloy powder A with a particle size of 5.0 μm. The second alloy ingot was subjected to hydrogen absorption at a hydrogen absorption temperature of 100℃ and a hydrogen pressure of 0.1 MPa for 2 h, and then dehydrogenated to a particle size of 200 μm by holding at 300℃ for 1.5 h. The ingot was further crushed by ball milling to obtain alloy powder B with a particle size of 4.0 μm.

[0056] (3) After mixing alloy powder A and alloy powder B at a mass ratio of 90:10, the mixture is pressed under a pressure of 16MPa to obtain a radial cylindrical green blank A.

[0057] (4) The green blank A is subjected to isostatic pressing treatment under a pressure of 150MPa for 5 minutes. The pressure is released in two stages. The first stage of pressure release is from 150MPa to 50MPa and held for 5 minutes. Then the pressure is released to atmospheric pressure and sintered at 1200℃ for 100 minutes. Then it is solution treated at 1180℃ for 5 hours and then cooled to 1150℃ for 5 hours. The magnet after sintering and solution treatment is isothermally aged at 800℃ for 30 hours. Then it is slowly cooled to 400℃ at a cooling rate of 0.5℃ / min and held for 5 hours. After being air-cooled to room temperature, the radial ring is machined by a hole-making machine with a hole-making head speed of 300rpm / min.

[0058] 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.

[0059] Table 1 Performance data of samarium cobalt rings

[0060]

[0061]

[0062] The radial samarium cobalt rings obtained in Examples 1-3 have good magnetic properties and a high yield rate. In Example 4, too much alloy powder B was added, which, because its main phase strength is stronger than the grain boundary, makes it easier to achieve intergranular fracture, significantly reducing the magnetic properties of the samarium cobalt rings. In Comparative Example 1, no alloy powder B was added, resulting in samarium cobalt rings with a low density. They needed to be pressed into rings under a high pressure of 40 MPa, which easily caused product cracking due to excessive stress. At the same time, due to the low density, the product bonding force was low, and the material edges would chip during the sizing process, reducing the yield rate. In Comparative Example 2, the cylindrical green blanks were subjected to isostatic pressing, sintering solution treatment, and aging treatment before sizing. This resulted in greater stress during sizing, which easily caused product cracking and reduced the yield rate.

[0063] 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 of producing a radial SmCo toroid, characterized by, The method comprises the following steps: (1) A first alloy ingot and a second alloy ingot are prepared according to element proportioning; a 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 0.8, a ranges from 0.03 to 0.35, 0.04≤b≤0.15, 0.01≤c≤0.05, 6.5≤z≤8.3; a chemical atomic formula of the second alloy ingot is SmCo y , 0.45<y≤0.6; (2) the first alloy ingot is subjected to mechanical crushing and airflow mill crushing in sequence to obtain alloy powder A, and the second alloy ingot is subjected to hydrogen crushing and ball mill crushing in sequence to obtain alloy powder B; (3) mixing alloy powder A and alloy powder B according to a mass ratio of 90:10~99:1, and then performing forming compression under a pressure of 15~20 MPa to obtain green body A, the green body A being a radial cylinder with an outer diameter ≥40 mm and a density of 5.0~5.5 g / cm 3 and performing hole sleeving processing on the middle part to obtain green body B; (4) a metal rod is inserted into the inner hole of the green body B, and a radial samarium-cobalt ring is obtained through isostatic pressing treatment, sintering solid solution and aging treatment.

2. The method of claim 1, wherein the radial Sm-Co ring is prepared by a process comprising: 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 claim 1, wherein the radial Sm-Co ring is prepared by a process comprising: In step (2), the particle size of the second alloy ingot after hydrogen crushing is 100-300 μm, and the particle size of the alloy powder B obtained after ball mill crushing is 3.5-4.5 μm.

4. The method of claim 1, wherein the radial Sm-Co ring is prepared by a process comprising: 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 10-30 MPa, and then the pressure is released to the atmospheric pressure after pressure maintaining for 1-10 min.

5. The method of claim 1, wherein the radial Sm-Co ring is prepared by a process comprising: 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, then heat treatment at 1140-1185 ℃ for 3-8 h, and finally air cooling to room temperature.

6. A radial ring, characterized in that The radial samarium-cobalt ring is prepared by the preparation method of the radial samarium-cobalt ring according to claim 1.

Images