Pressure heat treatment device for improving diffusion efficiency of sintered neodymium-iron-boron

Abstract

The utility model discloses a kind of pressure heat treatment devices for improving diffusion efficiency of sintered neodymium iron boron, it is related to neodymium iron boron processing technical field.The utility model, including vacuum furnace body, the vacuum furnace body is provided with material support, material support is used to place sintered neodymium iron boron magnet coated with diffusion source, and force link is inserted on material support.The utility model, vacuum furnace body is used as the main part of whole device, provides necessary high-temperature high-pressure environment guarantee for heat treatment process, material support is installed in the inside of vacuum furnace body, for placing neodymium iron boron magnet coated with diffusion source, when the temperature in vacuum furnace body reaches 300 DEG C, the pressure of hydraulic device is passed to pressure plate by force link, and then act on neodymium iron boron magnet surface, by controlling the output pressure of hydraulic device, even and controllable pressure is applied to neodymium iron boron magnet by force link and pressure plate, to improve diffusion efficiency of rare earth element along grain boundary in heat treatment process, improve the magnetic property of magnet.

Description

Technical Field

[0001] This utility model relates to the field of NdFeB processing technology, specifically to a pressure heat treatment device for improving the diffusion efficiency of sintered NdFeB. Background Technology

[0002] NdFeB (Neodymium Iron Boron) permanent magnets are widely used in electric vehicles, wind power generation, and consumer electronics due to their excellent magnetic properties and high energy density. To improve the magnetic properties of sintered NdFeB magnets, grain boundary diffusion technology is commonly employed. This technology has gained significant attention in the preparation of NdFeB permanent magnets in recent years. It involves forming a thin film of heavy rare earth elements (such as dysprosium (Dy) and terbium (Tb)) on the surface of the sintered NdFeB magnet and then subjecting it to high-temperature heat treatment. This allows the heavy rare earth elements to diffuse along the grain boundaries into the magnet's interior, thereby improving the magnet's coercivity (Hcj) and high-temperature performance. Compared to traditional methods of adding heavy rare earth alloys, grain boundary diffusion technology can significantly improve the magnet's coercivity without significantly reducing remanence, and it also greatly reduces the amount of heavy rare earth elements used, lowering costs. In recent years, researchers have attempted to improve diffusion efficiency and material properties by optimizing parameters such as temperature, pressure, and time during the grain boundary diffusion process.

[0003] Studies have shown that applying appropriate pressure can effectively improve the efficiency of grain boundary diffusion during magnet grain boundary diffusion treatment. However, existing pressure application methods still present many challenges. Traditional diffusion processes are complex, pressure control is difficult, and they are prone to instability in the diffusion process, thus affecting the quality and performance of the final product. Achieving precise pressure application and uniform pressure distribution remains a challenge in current technology.

[0004] To address this, a pressure heat treatment device is proposed to improve the diffusion efficiency of sintered NdFeB. Utility Model Content

[0005] The purpose of this invention is to provide a pressure heat treatment device for improving the diffusion efficiency of sintered NdFeB in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model specifically adopts the following technical solution: A pressure heat treatment apparatus for improving the diffusion efficiency of sintered NdFeB magnets includes a vacuum furnace body. A material support is provided inside the vacuum furnace body for placing sintered NdFeB magnets coated with a diffusion source. A force transmission rod is inserted into the material support, and a pressure plate is fixedly installed on the force transmission rod. A hydraulic device is provided on the surface of the vacuum furnace body, and the force transmission rod is connected to the hydraulic device. The hydraulic device is used to apply pressure to the pressure plate through the force transmission rod to perform pressure heat treatment on the NdFeB magnets.

[0007] Furthermore, the material support includes a support foot, a steel plate, and a graphite plate. The surface of the support foot is detachably mounted with a steel plate, the graphite plate is laid flat on the steel plate, and the neodymium iron boron magnet is laid flat on the graphite plate.

[0008] Furthermore, both the pressure plate and the steel plate have a graphite coating on one side wall, and the graphite coating is in contact with the surface of the neodymium iron boron magnet.

[0009] Furthermore, the force transmission rod includes a push rod and a force transmission bracket. The pressure plate is fixedly installed on the push rod, and the push rod is movably inserted into the steel plate. The push rod and the force transmission bracket are detachably installed and connected to the hydraulic device via the force transmission bracket.

[0010] Furthermore, both the force transmission rod and the material support are made of alloy steel that is not easily deformed.

[0011] Furthermore, the vacuum furnace body is also connected to a high vacuum system and a heating system. The high vacuum system is used to perform a vacuuming operation inside the vacuum furnace body, and the heating system is used to heat the sintered NdFeB magnets inside the vacuum furnace body.

[0012] Furthermore, the hydraulic device can adjust the pressure applied to the neodymium iron boron magnet by controlling its power, and when the heating temperature reaches 300°C, the hydraulic device is activated to apply pressure to the neodymium iron boron magnet through the force transmission rod and pressure plate.

[0013] The beneficial effects of this utility model are as follows: This device aims to improve the diffusion efficiency of sintered NdFeB magnets. Its core lies in achieving heat treatment of NdFeB magnets by applying external pressure. The vacuum furnace body, as the main part of the entire device, provides the necessary high-temperature and high-pressure environment for the heat treatment process. The material support is installed inside the vacuum furnace body to hold the NdFeB magnets coated with diffusion sources. When the temperature inside the vacuum furnace reaches 300°C, the pressure of the hydraulic device is transmitted to the pressure plate through the force transmission rod, and then acts on the surface of the NdFeB magnet. By controlling the output pressure of the hydraulic device, uniform and controllable pressure is applied to the NdFeB magnet through the force transmission rod and the pressure plate, thereby improving the diffusion efficiency of rare earth elements along the grain boundaries during the heat treatment process and improving the magnetic properties of the magnet. Attached Figure Description

[0014] Figure 1 This is a three-dimensional structural schematic diagram of Embodiment 1 of this utility model; Figure 2 This is a utility model Figure 1 Top view; Figure 3 This is a utility model Figure 1 A partial schematic diagram; Figure 4This is a three-dimensional structural schematic diagram of Embodiment 2 of this utility model; Figure 5 This is a utility model Figure 4 Top view; Figure 6 This is a utility model Figure 4 A partial schematic diagram; Reference numerals: 1. Vacuum furnace body; 2. Hydraulic device; 3. Force transmission rod; 301. Push rod; 302. Force transmission bracket; 4. Pressure plate; 5. Material support; 501. Support foot; 502. Steel plate; 503. Graphite plate; 6. Neodymium iron boron magnet. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0016] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0017] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0018] In the description of the embodiments of this utility model, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0019] like Figures 1 to 6As shown, a pressure heat treatment apparatus for improving the diffusion efficiency of sintered NdFeB magnets includes a vacuum furnace body 1, wherein the vacuum furnace body 1 can be rectangular or circular, etc., and a material support 5 is provided inside the vacuum furnace body 1. The material support 5 is used to place sintered NdFeB magnets 6 coated with a diffusion source. Figure 3 and Figure 6 As shown, specifically, the material support 5 includes a support foot 501, a steel plate 502 and a graphite plate 503. The steel plate 502 is detachably mounted on the surface of the support foot 501. The graphite plate 503 is laid flat on the steel plate 502, and the neodymium iron boron magnet 6 is laid flat on the graphite plate 503.

[0020] More specifically, the graphite plate 503 not only withstands high temperatures but also supports the placement of the neodymium iron boron magnet 6. At the same time, the good thermal conductivity of the graphite plate helps to ensure uniform heat transfer during the heat treatment process, ensuring that the neodymium iron boron magnet 6 is heated evenly, thereby improving the diffusion efficiency and the consistency of magnet performance.

[0021] A force transmission rod 3 is inserted into the material support 5, and a pressure plate 4 is fixedly installed on the force transmission rod 3; for example Figure 3 and Figure 6 As shown, specifically, the force transmission rod 3 includes a push rod 301 and a force transmission bracket 302. The pressure plate 4 is fixedly installed on the push rod 301, and the push rod 301 is movably inserted into the steel plate 502. The push rod 301 and the force transmission bracket 302 are detachably installed and connected to the hydraulic device 2 via the force transmission bracket 302.

[0022] More specifically, the push rod 301 and the force transmission bracket 302 are detachable, which not only facilitates the assembly, disassembly and maintenance of the device, but also connects the force transmission bracket 302 to the hydraulic device 2, accurately transmitting the thrust generated by the hydraulic device 2 to the pressure plate 4, ensuring effective pressure transmission and stability of the heat treatment process.

[0023] One embodiment of the push rod 301 and the force transmission bracket 302 is as follows: like Figure 1 , Figure 2 and Figure 3 As shown, there are two sets of force transmission brackets 302. Two sets of hydraulic devices 2 are installed on the vacuum furnace 1. The ends of the two sets of hydraulic devices 2 are respectively connected to the two sets of force transmission brackets 302, and the pressure plate 4 on its push rod 301 is set as a whole. The second embodiment of push rod 301 and force transmission bracket 302 is as follows: like Figure 4 , Figure 5 and Figure 6As shown, the two ends of the force transmission bracket 302 are connected to the push rod 301. Only one set of hydraulic devices 2 needs to be installed on the vacuum aluminum 1. The end of one set of hydraulic devices 2 is connected to the middle of the force transmission bracket 302, and the pressure plate 4 on the push rod 301 is set as a single independent piece.

[0024] In some practical applications, both the pressure plate 4 and the steel plate 502 have a graphite coating on one side wall, and the graphite coating is in contact with the surface of the neodymium iron boron magnet 6.

[0025] More specifically, during the pressure heat treatment process, the graphite coating plays a crucial isolating role. On the one hand, the graphite coating can prevent the pressure plate 4 and the steel plate 502 from directly contacting the surface of the NdFeB magnet 6, avoiding adhesion and scratches between the metal materials and protecting the surface quality of the magnet. On the other hand, the good lubrication properties of the graphite coating reduce the frictional resistance during pressure transmission, ensuring that the pressure can be more evenly distributed on the surface of the NdFeB magnet 6, thereby improving the grain boundary diffusion effect and enhancing the coercivity and high-temperature performance of the magnet.

[0026] A hydraulic device 2 is provided on the surface of the vacuum furnace body 1. A force transmission rod 3 is connected to the hydraulic device 2. The hydraulic device 2 is used to apply pressure to the pressure plate 4 through the force transmission rod 3 to perform pressure heat treatment on the neodymium iron boron magnet 6.

[0027] In some practical applications, both the force transmission rod 3 and the material support 5 are made of alloy steel that is not easily deformed.

[0028] More specifically, in high-temperature and high-pressure working environments, the high strength and high rigidity of alloy steel can ensure the structural stability of the force transmission rod 3 and the material support 5, and prevent uneven pressure transmission caused by material deformation.

[0029] In some practical applications, the vacuum furnace body 1 is also connected to a high vacuum system and a heating system. The high vacuum system is used to perform vacuuming operations inside the vacuum furnace body 1, and the heating system is used to heat the sintered NdFeB magnets 6 inside the vacuum furnace body 1.

[0030] More specifically, the main function of the high vacuum system is to perform a vacuuming operation inside the vacuum furnace 1, effectively removing impurities such as oxygen and nitrogen from the air, and preventing the neodymium iron boron magnet 6 from undergoing adverse reactions such as oxidation and nitridation at high temperatures. The heating system adopts resistance wire heating, which can uniformly heat the neodymium iron boron magnet 6 inside the vacuum furnace 1 according to the preset heating rate and temperature curve.

[0031] In some practical applications, the hydraulic device 2 can adjust the pressure applied to the neodymium iron boron magnet 6 by controlling its power, and when the heating temperature reaches 300°C, the hydraulic device 2 is activated to apply pressure to the neodymium iron boron magnet 6 through the force transmission rod 3 and the pressure plate 4.

[0032] More specifically, when the temperature rises to around 300℃, the atomic mobility inside the NdFeB magnet 6 increases. At this temperature, applying pressure can more effectively promote the diffusion of rare earth elements along the grain boundaries into the magnet, improving the diffusion depth and uniformity. By precisely controlling the power of the hydraulic device 2, the pressure on the NdFeB magnet 6 can be precisely adjusted to ensure a uniform and stable pressure distribution, thereby optimizing the grain boundary diffusion effect, improving the coercivity and overall magnetic properties of the magnet, and meeting the requirements for the preparation of high-performance NdFeB permanent magnet materials.

[0033] In summary, this device aims to improve the diffusion efficiency of sintered NdFeB magnets 6. Its core lies in achieving heat treatment of NdFeB magnets 6 by applying external pressure. The vacuum furnace body 1, as the main body of the entire device, provides the necessary high-temperature and high-pressure environment for the heat treatment process. The material support 5 is installed inside the vacuum furnace body 1 to place the NdFeB magnets 6 coated with diffusion sources. When the temperature inside the vacuum furnace body 1 reaches 300℃, the pressure of the hydraulic device 2 is transmitted to the pressure plate 4 through the force transmission rod 3, and then acts on the surface of the NdFeB magnets 6. By controlling the output pressure of the hydraulic device 2, uniform and controllable pressure is applied to the NdFeB magnets 6 through the force transmission rod 3 and the pressure plate 4, thereby improving the diffusion efficiency of rare earth elements along the grain boundaries during the heat treatment process and improving the magnetic properties of the magnets.

[0034] Example 1: Commercial magnets were selected as the substrate for grain boundary diffusion, and the magnet thickness was uniformly cut to 5 mm.

[0035] Then, a layer of Tb alloy diffusion source is printed on the surface of the magnet using a screen printing process, with the diffusion source weight increase being 0.5wt%.

[0036] After drying, these magnets coated with diffusion source are then neatly stacked on the material support plate, with graphite plates separating the magnets from the steel plates.

[0037] Then, the graphite-coated side of the pressure plate is pressed tightly against the placed magnets, and both ends are connected and fixed to the force transmission rods. When laying multiple layers of material supports, the material supports and pressure plates are installed alternately and systematically.

[0038] Next, close the furnace door and start the vacuum system to ensure that the furnace reaches the required high vacuum level, generally greater than 8*10-3Pa.

[0039] Then, heating begins according to the set program, with a heating rate of 10 degrees per minute, and the final target temperature is 910℃, which is maintained for 10 hours.

[0040] When the heating temperature reaches 300℃, the hydraulic device is activated to continuously apply pressure, which remains constant at 2kPa.

[0041] The furnace temperature was 910℃. After holding at that temperature for 10 hours, the pressure was removed, and the furnace body began to cool down rapidly with air cooling.

[0042] Example 2: Unlike Example 1, the applied pressure is changed to 1 kPa. Comparative Example 1: Unlike Example 1, the applied pressure is changed to 0 kPa, i.e. there is no pressure diffusion.

[0043] The experimental data are shown in the table below: The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A pressure heat treatment apparatus for improving the diffusion efficiency of sintered NdFeB magnets, characterized in that, The system includes a vacuum furnace body (1), inside which a material support (5) is provided. The material support (5) is used to place sintered NdFeB magnets (6) coated with a diffusion source. A force transmission rod (3) is inserted into the material support (5), and a pressure plate (4) is fixedly installed on the force transmission rod (3). A hydraulic device (2) is provided on the surface of the vacuum furnace body (1). The force transmission rod (3) is connected to the hydraulic device (2). The hydraulic device (2) is used to apply pressure to the pressure plate (4) through the force transmission rod (3) to perform pressure heat treatment on the NdFeB magnets (6).

2. The pressure heat treatment apparatus for improving the diffusion efficiency of sintered NdFeB according to claim 1, characterized in that, The material support (5) includes a support foot (501), a steel plate (502) and a graphite plate (503). The surface of the support foot (501) is detachably mounted with the steel plate (502), the graphite plate (503) is laid flat on the steel plate (502), and the neodymium iron boron magnet (6) is laid flat on the graphite plate (503).

3. The pressure heat treatment apparatus for improving the diffusion efficiency of sintered NdFeB according to claim 2, characterized in that, The pressure plate (4) and the steel plate (502) are both provided with a graphite coating on one side wall, and the graphite coating is in contact with the surface of the neodymium iron boron magnet (6).

4. The pressure heat treatment apparatus for improving the diffusion efficiency of sintered NdFeB according to claim 1, characterized in that, The force transmission rod (3) includes a push rod (301) and a force transmission bracket (302). The pressure plate (4) is fixedly installed on the push rod (301), and the push rod (301) is movably inserted into the steel plate (502). The push rod (301) and the force transmission bracket (302) are detachably installed and connected to the hydraulic device (2) via the force transmission bracket (302).

5. The pressure heat treatment apparatus for improving the diffusion efficiency of sintered NdFeB according to claim 1, characterized in that, Both the force transmission rod (3) and the material support (5) are made of alloy steel that is not easily deformed.

6. The pressure heat treatment apparatus for improving the diffusion efficiency of sintered NdFeB according to claim 1, characterized in that, The vacuum furnace body (1) is also connected to a high vacuum system and a heating system. The high vacuum system is used to perform vacuuming operations inside the vacuum furnace body (1), and the heating system is used to heat the sintered NdFeB magnets (6) inside the vacuum furnace body (1).

7. The pressure heat treatment apparatus for improving the diffusion efficiency of sintered NdFeB according to claim 1, characterized in that, The hydraulic device (2) can adjust the pressure applied to the neodymium iron boron magnet (6) by controlling its power, and when the heating temperature reaches 300°C, the hydraulic device (2) is activated to apply pressure to the neodymium iron boron magnet (6) through the force transmission rod (3) and the pressure plate (4).

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