Preparation method of high-performance samarium-cobalt radiation ring

Abstract

The application belongs to the technical field of magnets and relates to a preparation method of a high-performance SmCo radiation ring, which comprises the following steps: vacuum smelting raw materials into ingots after mixing, crushing the ingots into magnetic powders, orientation forming the magnetic powders, and obtaining the high-performance SmCo radiation ring after sintering and heat treatment; the orientation forming of the magnetic powders is performed in a radiation orientation forming device, and the radiation orientation forming device adopts an N-N or S-S pole tip pair to top an additional radiation magnetic field; the sintering comprises the following steps: heating to 1100-1300 DEG C through a stage, keeping for 1-5 h, then keeping at 1000-1200 DEG C for 1-5 h, and finally reducing to room temperature through a stage. The preparation method of the SmCo radiation ring effectively improves the brittleness of the magnet and the uniformity of the magnetic ring orientation, and solves the problems of easy cracking and surface magnetic uniformity of the SmCo radiation ring.

Description

Technical Field

[0001] This invention belongs to the field of magnet technology and relates to a method for preparing a high-performance samarium cobalt radiation ring. Background Technology

[0002] Samarium cobalt magnets are rare-earth permanent magnets that include SmCo5 (1:5) and Sm2Co. 17 (2:17). Compared to NdFeB magnets, the most significant characteristic of SmCo magnets is their superior corrosion resistance and oxidation resistance, with a BH (maximum value) ranging from 16 MGOe to 32 MGOe. Therefore, it is the only rare-earth magnet whose performance can approach that of lower-grade sintered NdFeB magnets. SmCo magnets have a high-temperature resistance range of 250-350℃ and a Curie temperature of 700-840℃, thus requiring no coating. In particular, the excellent magnetic stability of SmCo magnets allows them to be used in very complex working environments. They are mainly used in aerospace, defense, high-performance permanent magnet rotors, microwave equipment, communications, medical equipment, instruments, various magnetic transmission devices, sensors, magnetic processors, voice coil motors, magnetic cranes, etc.

[0003] Radiation magnetic rings are a new product developed in recent years, representing another new direction in the development of magnetic materials. They have advantages such as easy assembly, excellent magnetic circuits, high reliability, and high precision. Therefore, the market demand for multi-pole radiation-oriented magnetic rings is increasing. However, samarium cobalt radiation ring magnets are less widely used in the market, mainly because samarium cobalt material has a pinning coercivity mechanism and is inherently brittle, leading to difficulties in orientation and cracking of samarium cobalt radiation rings. Summary of the Invention

[0004] The purpose of this invention is to address the problems of difficult orientation, high brittleness, and low processing yield of samarium cobalt radiation rings in the prior art, and to provide a method for preparing high-performance samarium cobalt radiation rings, which can effectively improve the surface magnetic uniformity of the radiation ring, reduce the brittleness of the material, and increase the processing yield of the magnetic ring.

[0005] One object of the present invention is to provide a method for preparing a high-performance samarium cobalt radiation ring, comprising the following steps:

[0006] After the raw materials are mixed, they are vacuum melted into ingots, the ingots are crushed into magnetic powder, the magnetic powder is oriented and shaped, and after sintering and heat treatment, a high-performance samarium cobalt radiation ring is obtained.

[0007] The magnetic powder orientation molding is carried out in a radiation orientation molding device, which uses an external radiation magnetic field with NN or SS pole heads facing each other.

[0008] The sintering process includes: gradually heating to 1100-1300℃ and holding for 1-5 hours, then holding at 1000-1200℃ for 1-5 hours, and finally gradually cooling down to room temperature.

[0009] Preferably, after the ingot is crushed into magnetic powder, Cu is coated on the surface of the magnetic powder. a M b Alloy powder, wherein M is one or more elements selected from Co, Zr, Fe, Dy, Tb, Sm, and Gd, and a+b=100, 0≤a≤100, and 0≤b≤100.

[0010] As a preferred option, 0 < a ≤ 100 and 0 ≤ b < 100.

[0011] As a preferred option, 50 < a ≤ 90, 10 ≤ b < 50.

[0012] As a preferred option, Cu a M b The alloy addition mass is (0, 10%) of the magnetic powder mass, where (0, 10%) represents a range of 0 to 10%, excluding 0 and including 10%.

[0013] Preferably, the radiation orientation forming device includes: an upper mold, an upper pressure head, a die, a lower mold, a lower die mandrel, a lower pressure head, and an electromagnet.

[0014] Preferably, the upper mold, die, and lower mold core rod are made of magnetically conductive material.

[0015] Preferably, the radiation orientation forming device uses an electromagnet to form an external radiation magnetic field with NN or SS poles facing each other.

[0016] As a preferred embodiment, the magnetic powder orientation molding process includes: after the magnetic powder is filled, the lower mold core rod contacts the upper mold, then an external radiating magnetic field is generated, and the upper pressure head moves downward synchronously with the mold to orient and densify the magnetic powder.

[0017] Preferably, the staged heating includes: heating from room temperature to 250-450℃, holding at that temperature for 0.1-4 hours, continuing to heat to 600-1000℃, holding at that temperature for 0.1-4 hours, then heating to 1000-1200℃, holding at that temperature for 0.1-4 hours, and then holding at 1100-1300℃ for 1-5 hours.

[0018] Preferably, the staged cooling includes: cooling to 600-800°C at a cooling rate of 50-200°C / min, and then cooling to room temperature at a cooling rate of 5-50°C / min.

[0019] Preferably, the heat treatment includes: heating from room temperature to 800-900℃, holding at that temperature for 10-24 hours, cooling to 650-750℃, holding at that temperature for 1-5 hours, cooling to 550-650℃, holding at that temperature for 1-5 hours, cooling to 450-550℃, holding at that temperature for 1-5 hours, and cooling to 350-450℃, holding at that temperature for 1-10 hours.

[0020] Preferably, the heating rate during the heat treatment process is 3-7°C / min.

[0021] Preferably, the cooling rate during the heat treatment process is 0.1-5℃ / min.

[0022] Another object of the present invention is to provide a high-performance samarium cobalt radiation ring, which is prepared by the above-described preparation method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. This invention has developed a special sintering and heat treatment process for samarium cobalt radiation rings, which greatly improves the brittleness of the magnets and increases the processing yield of the radiation rings;

[0025] 2. The present invention coats the surface of magnetic powder with an alloy powder formed by Cu and one or more of Co, Zr, Fe, Dy, Tb, Sm and Gd, which can effectively improve the brittleness of samarium cobalt radiation rings;

[0026] 3. In this invention, the Cu content on the surface of the magnetic powder is preferably higher than that of element M. a M b The radiation ring prepared from alloy powder has higher bending strength;

[0027] 4. The radiation orientation forming device of the present invention uses an external radiation magnetic field with NN or SS pole heads facing each other. The magnetic field is symmetrically introduced onto the magnetic powder through the magnetic guiding structure on both sides. The magnetic field strength is relatively large, which can make the magnetic powder achieve good orientation. At the same time, due to the design of the magnetic guiding structure, the small-sized radiation ring can achieve good orientation.

[0028] 5. The preparation method of the samarium cobalt radiation ring of the present invention effectively improves the brittleness of the magnet and solves the problem of samarium cobalt radiation ring being difficult to sinter and prone to cracking. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view of the radiation orientation forming device;

[0030] Figure 2 This is a magnetic circuit simulation diagram of a radiation orientation forming device;

[0031] Figure 3 Typical magnetic waveform diagram of a radiation ring surface.

[0032] Figure 1 In the middle: ①: upper mold, ②: upper pressure head, ③: mold, ④: lower mold, ⑤: lower mold core rod, ⑥: lower pressure head, ⑦: magnetic powder, ⑧: electromagnet. Detailed Implementation

[0033] The radial orientation forming apparatus of the present invention will be described in detail below; however, these descriptions are exemplary for better understanding, and the disclosure of the present invention is not limited thereto. Furthermore, the accompanying drawings used herein are merely for better illustration of the disclosed invention and are not intended to limit the scope of protection.

[0034] The magnetic powder orientation molding of the present invention is performed in a radiation orientation molding apparatus, such as... Figure 1 As shown, the radiation orientation forming device includes: an upper mold ①, an upper pressure head ②, a mold ③, a lower mold ④, a lower mold core rod ⑤, a lower pressure head ⑥, and an electromagnet ⑧. During the orientation forming process, magnetic powder ⑦ is first placed inside the mold ③. After the magnetic powder is filled, the entire radiation orientation forming device is mounted on the press. Then, the lower mold core rod ⑤ first contacts the upper mold ①, and simultaneously, an NN or SS pole-to-pole magnetic field is generated by the electromagnet ⑧. The upper pressure head ② and the mold ③ move downwards synchronously at a certain rate to orient and densify the powder. After completion, a reverse demagnetizing magnetic field is applied to the electromagnet ⑧ to demagnetize it. The upper mold ① moves upwards, the lower core rod ⑤ moves downwards, and the mold ③ moves downwards, completing the orientation forming process.

[0035] The radial orientation molding device of this invention employs an external magnetic field with NN or SS poles facing each other. Traditional radial orientation molding devices often use an N or S magnetic field applied around the molding device. After the mold rotates one or more times, the magnetic powder achieves radial orientation. This method has limitations when preparing radial rings with small inner and outer diameters, as the magnetic field easily penetrates the entire mold, making it difficult to orient the magnetic powder. The method of using an external magnetic field with NN or SS poles facing each other successfully solves this problem. Electromagnets ⑧ are arranged above and below the radial orientation molding device to generate magnetic fields of the same polarity. These magnetic fields of the same polarity on both sides are symmetrically introduced onto the magnetic powder ⑦ through a magnetically conductive structure (the upper mold ①, mold ③, and lower mold core rod ⑤ are made of magnetically conductive material, forming a magnetically conductive structure). Figure 2 As shown in the magnetic circuit simulation diagram, this method generates a large magnetic field strength, which can effectively radiatively magnetize and orient the added magnetic powder. At the same time, due to the design of the magnetically conductive structure, the small-sized radiative ring can achieve good orientation.

[0036] 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 specific scope of the present invention. Furthermore, the accompanying drawings used herein are merely for better illustrating the content disclosed in the present invention and do not limit the scope of protection. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used in the art, and the methods used in the embodiments are all conventional methods in the art.

[0037] Example 1

[0038] Vacuum melting into ingots: After mixing the raw materials, alloys are melted using vacuum induction melting technology to prepare Sm(Co) ingots. 0.66 Fe 0.3 Cu 0.01 Zr 0.03 ) 7.2 Ingots.

[0039] Crushing the ingot into magnetic powder: Crushing the alloy ingot into magnetic powder of 2000-3000μm.

[0040] Orientation molding: 85g of magnetic powder is placed in mold ③, and the upper pressure head ② has the following specifications: The specifications of the downward pressure head ⑥ are as follows: The lower mold core rod ⑤ has the following specifications: The orientation current is 200A. Two electromagnets (⑧) are arranged vertically in the radiation orientation forming device to generate a magnetic field of the same polarity to radiatively magnetize and orient the magnetic powder. Simultaneously, the entire radiation orientation forming device is mounted on a press, and the powder is formed under the action of the press. The specifications of the formed blank are as follows:

[0041] Sintering process: The oriented blanks are first subjected to a sintering process. Sintering is carried out in a tube sintering furnace, and the vacuum is evacuated to 9×10. -3 Pa, raise the temperature from room temperature to 300℃ for 2 hours and hold for 2 hours, raise the temperature to 800℃ for 2.5 hours and hold for 1 hour, raise the temperature to 1100℃ for 1 hour and hold for 1 hour, raise the temperature to 1200℃ for 1.5 hours and hold for 4 hours, lower the temperature to 1170℃ for 3 hours, lower the temperature to 700℃ at 100℃ / min, and then lower the temperature to room temperature at 20℃ / min.

[0042] Heat treatment process: Heat from room temperature to 830℃ for 2 hours and hold for 12 hours, then cool down to 700℃ for 1 hour and hold for 1 hour, then cool down to 600℃ for 1 hour and hold for 1 hour, then cool down to 500℃ for 1 hour and hold for 1 hour, then cool down to 400℃ for 4 hours and hold for 4 hours, then cool with the furnace.

[0043] Example 2

[0044] The difference between Example 2 and Example 1 is that Example 2 includes a coating process between the ingot crushing into magnetic powder and the orientation forming step: Cu powder is coated onto the surface of the magnetic powder by spraying. The particle size of the Cu powder is 3-4 μm, and the amount of Cu powder added is 4 wt% of the mass of the magnetic powder. Everything else is the same as in Example 1.

[0045] Example 3

[0046] The difference between Example 3 and Example 1 is that Example 3 includes a coating process between the ingot crushing into magnetic powder and the orientation forming step: Co powder is coated onto the surface of the magnetic powder by spraying. The particle size of the Co powder is 3-4 μm, and the amount of Co powder added is 4 wt% of the mass of the magnetic powder. Everything else is the same as in Example 1.

[0047] Example 4

[0048] The difference between Example 4 and Example 1 is that Example 4 includes a coating process between the ingot crushing into magnetic powder and the orientation forming step: Cu is coated onto the surface of the magnetic powder by spraying. 80 Co 20 Alloy powder, Cu 80 Co 20 The particle size range of the alloy powder is 3-4 μm, Cu 80 Co 20 The amount of alloy powder added was 4 wt% of the magnetic powder mass. Everything else was the same as in Example 1.

[0049] Example 5

[0050] The difference between Example 5 and Example 1 is that Example 5 includes a coating process between the ingot crushing into magnetic powder and the orientation forming step: Cu is coated onto the surface of the magnetic powder by spraying. 20 Co 80 Alloy powder, Cu 20 Co 80 The particle size range of the alloy powder is 3-4 μm, Cu 20 Co 80 The amount of alloy powder added was 4 wt% of the magnetic powder mass. Everything else was the same as in Example 1.

[0051] Example 6

[0052] The difference between Example 6 and Example 1 is that Example 6 includes a coating process between the ingot crushing into magnetic powder and the orientation forming step: Zr powder is coated onto the surface of the magnetic powder by spraying. The particle size of the Zr powder is 3-4 μm, and the amount of Zr powder added is 4 wt% of the mass of the magnetic powder. Everything else is the same as in Example 1.

[0053] Example 7

[0054] The difference between Example 7 and Example 1 is that Example 7 includes a coating process between the ingot crushing into magnetic powder and the orientation forming step: Cu is coated onto the surface of the magnetic powder by spraying. 70 Zr 30 Alloy powder, Cu 70 Zr 30 The particle size range of the alloy powder is 3-4 μm, Cu 70 Zr30 The amount of alloy powder added was 4 wt% of the magnetic powder mass. Everything else was the same as in Example 1.

[0055] Example 8

[0056] The difference between Example 8 and Example 1 is that Example 8 includes a coating process between the ingot crushing into magnetic powder and the orientation forming step: Cu is coated onto the surface of the magnetic powder by spraying. 30 Zr 70 Alloy powder, Cu 30 Zr 70 The particle size range of the alloy powder is 3-4 μm, Cu 30 Zr 70 The amount of alloy powder added was 4 wt% of the magnetic powder mass. Everything else was the same as in Example 1.

[0057] Example 9

[0058] Vacuum melting into ingots: After mixing the raw materials, alloys are melted using vacuum induction melting technology to prepare Sm(Co) ingots. 0.66 Fe 0.3 Cu 0.01 Zr 0.03 ) 7.2 Ingots.

[0059] Crushing the ingot into magnetic powder: Crushing the alloy ingot into magnetic powder of 2000-3000μm.

[0060] Coating: Cu is coated onto the surface of the magnetic powder by spraying. 75 Co 25 Alloy powder, Cu 75 Co 25 The particle size range of the alloy powder is 3-4 μm, Cu 75 Co 25 The amount of alloy powder added is 6 wt% of the magnetic powder mass.

[0061] Orientation molding: 30g of magnetic powder is placed in mold ③, and the upper pressure head ② has the following specifications. The specifications of the downward pressure head ⑥ are as follows: The lower mold core rod ⑤ has the following specifications: The orientation current is 150A. Two electromagnets (⑧) are arranged vertically in the radiation orientation forming device to generate a magnetic field of the same polarity to radiatively magnetize and orient the magnetic powder. Simultaneously, the entire radiation orientation forming device is mounted on a press, and the powder is formed under the action of the press. The specifications of the formed blank are as follows:

[0062] Sintering process: The oriented blanks are first subjected to a sintering process. Sintering is carried out in a tube sintering furnace, and the vacuum is evacuated to 9×10. -3Pa, raise the temperature from room temperature to 350℃ for 2 hours and hold for 1.5 hours, raise the temperature to 900℃ for 3 hours and hold for 1.5 hours, raise the temperature to 1200℃ for 1 hour and hold for 1 hour, raise the temperature to 1280℃ for 4 hours, lower the temperature to 1200℃ for 4 hours, lower the temperature to 750℃ at 105℃ / min, and then lower the temperature to room temperature at 22℃ / min.

[0063] Heat treatment process: Heat from room temperature to 820℃ for 2.5 hours and hold for 15 hours, then cool down to 720℃ and hold for 1.5 hours, then cool down to 620℃ and hold for 1.5 hours, then cool down to 520℃ and hold for 1.5 hours, then cool down to 420℃ and hold for 5 hours, and finally cool with the furnace.

[0064] Comparative Example 1

[0065] The difference between Comparative Example 1 and Example 1 is as follows:

[0066] The heat treatment process of Comparative Example 1 is as follows: heating from room temperature to 830℃ for 2 hours and holding for 12 hours, cooling down to 400℃ for 4 hours and holding for 7 hours, and then cooling with the furnace.

[0067] Everything else is the same as in Example 1.

[0068] The performance of the samarium cobalt radiation rings of Examples 1-9 and Comparative Example 1 was tested using a surface magnetic resonance analyzer and a three-point bending strength analyzer. The results are shown in Table 1. Typical surface magnetic resonance waveforms are shown below. Figure 3 , Figure 3 In the center: the horizontal axis represents the angle of rotation of the probe along the surface of the magnetic ring, and the vertical axis represents the surface magnetic intensity of the magnetic ring.

[0069] Table 1. Performance test results of samarium-cobalt radiation rings in Examples 1-9 and Comparative Examples 1-2.

[0070]

[0071] *The surface magnetic intensity is the surface magnetic intensity corresponding to 360°.

[0072] Comparative Example 1 uses a conventional heat treatment process, directly cooling from 830℃ to 400℃. The bending strength of the samarium cobalt radiation ring prepared in Comparative Example 1 is much lower than that in Example 1. This shows that the present invention improves the bending strength of the magnet, reduces the brittleness of the magnet, and increases the processing qualification rate of the radiation ring through a special sintering process and heat treatment process.

[0073] Performance data from Examples 2-9 show that coating Cu on the surface of magnetic powder... a M b The powder can effectively improve the flexural strength of the samarium cobalt radiation ring, while Example 4, which involves coating Cu... 80 Co 20 and Cu coating in Example 7 70 Zr30 The prepared samarium cobalt radiation ring has better bending strength and a more significant improvement in magnet performance.

[0074] In Example 9, the radiation forming device designed and developed in the patent is used to prepare a radiation ring magnet with a smaller inner and outer diameter, which makes up for the shortcomings of the traditional rotary radiation press.

[0075] All aspects, embodiments, and features of this invention should be considered illustrative in all respects and not limiting of the invention; the scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0076] In the preparation method of this invention, the order of the steps is not limited to the listed order. For those skilled in the art, variations in the order of the steps without creative effort are also within the scope of protection of this invention. Furthermore, two or more steps or actions can be performed simultaneously.

[0077] Finally, it should be noted that the specific embodiments described herein are merely illustrative examples 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 specific 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 preparing a high-performance samarium-cobalt radiation ring, characterized in that, Includes the following steps: After the raw materials are mixed, they are vacuum melted into ingots, the ingots are crushed into magnetic powder, the magnetic powder is oriented and shaped, and after sintering and heat treatment, a high-performance samarium cobalt radiation ring is obtained. The magnetic powder orientation molding is carried out in a radiation orientation molding device, which uses an external radiation magnetic field with NN or SS pole heads facing each other. After the ingot is crushed into magnetic powder, Cu is coated on the surface of the magnetic powder. a M b Alloy powder, wherein M is Co or Zr, a+b=100, 50<a≤90, 10≤b<50; The sintering process includes: heating from room temperature to 250-450℃ and holding for 0.1-4 hours, then heating to 600-1000℃ and holding for 0.1-4 hours, then heating to 1000-1200℃ and holding for 0.1-4 hours, then holding at 1100-1300℃ for 1-5 hours, then cooling to 600-800℃ at a cooling rate of 50-200℃ / min, and then cooling to room temperature at a cooling rate of 5-50℃ / min. The heat treatment includes: heating from room temperature to 800-900℃, holding at that temperature for 10-24 hours, cooling to 650-750℃, holding at that temperature for 1-5 hours, cooling to 550-650℃, holding at that temperature for 1-5 hours, cooling to 450-550℃, holding at that temperature for 1-5 hours, cooling to 350-450℃, and holding at that temperature for 1-10 hours.

2. The preparation method according to claim 1, characterized in that, Cu a M b The mass of alloy powder added is (0, 10%) of the mass of magnetic powder.

3. The preparation method according to claim 1, characterized in that, The radiation orientation forming device includes: an upper mold, an upper pressure head, a die, a lower mold, a lower die mandrel, a lower pressure head, and an electromagnet.

4. The preparation method according to claim 3, characterized in that, The upper mold, die, and lower mold core rod are made of magnetically conductive material.

5. The preparation method according to claim 3, characterized in that, The magnetic powder orientation molding process includes: after the magnetic powder is filled, the lower mold core rod contacts the upper mold, then an external radiation magnetic field is generated, and the upper pressure head moves downward synchronously with the mold to orient and densify the magnetic powder.

6. A high-performance samarium-cobalt radiation ring, characterized in that, It is prepared by the preparation method described in claim 1.

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