Crystal texture type R2Fe14B rare earth magnetic powder and preparation method and device thereof

Abstract

The invention relates to the field of rare earth magnetic materials, and provides crystal texture type R2Fe14B rare earth magnetic powder and a preparation method and device thereof.The preparation method comprises the steps that S1, metal steam is prepared, specifically, an evaporation material is placed in an evaporation chamber and heated under the vacuum condition to form metal steam; and S2, preparation of R2Fe14B magnetic powder HDDR: preparing R2Fe14B magnetic powder in an HDDR furnace, introducing metal steam into the HDDR furnace, directly depositing a metal layer on the surface of the R2Fe14B magnetic powder, carrying out evaporation-grain boundary diffusion heat treatment, carrying out heat preservation for 5-90 minutes, stopping heating, and then rapidly cooling to 100-200 DEG C along with the furnace to obtain the anisotropic crystal texture type R2Fe14B magnetic powder. According to the preparation method, the coercivity, the temperature stability and the corrosion resistance of the magnetic powder are remarkably improved, procedures are reduced, and the production efficiency is improved; and magnetic powder oxidation and abnormal grain growth can be avoided.

Description

Technical Field

[0001] The present invention relates to the field of rare earth magnetic materials, in particular to a crystal texture type R2Fe 14 B rare earth magnetic powder and its preparation method and device. Background Art

[0002] Neodymium iron boron (NdFeB) materials, due to their excellent magnetic properties, are widely used in high-tech fields such as new energy vehicles, wind power, and industrial robotics. With the development of low-carbon and environmentally friendly industries and the continued deepening of intelligent manufacturing, demand for NdFeB materials is increasing annually. Magnetic powder is a key material in the manufacture of NdFeB products. The HDDR process (hydrogenation, disproportionation, desorption, and recombination) is an efficient and economical method for preparing anisotropic NdFeB magnetic powder. Since its development in 1989 by Takeshita T of Mitsubishi Corporation in Japan, researchers have continuously improved the HDDR process, resulting in continuous improvements in magnetic powder performance.

[0003] The HDDR process is briefly described as follows: under a certain temperature and hydrogen pressure, the coarse grain R2Fe 14 The B master alloy absorbs hydrogen and breaks down and disproportionates into Fe2B, α-Fe and RH x Then the hydrogen pressure is reduced, the disproportionate products are dehydrogenated and recombined into R2Fe 14 B phase. By adding alloy elements or adjusting the appropriate hydrogen pressure and temperature, R2Fe 14 B grains are refined and a certain crystal orientation is produced, thereby producing magnetic powder with magnetic anisotropy. The magnetic anisotropy of HDDR RFeB magnetic powder comes from the R2Fe in the magnetic powder. 14The crystal texture of the B phase, combined with the performance of bonded magnets made with anisotropic magnetic powders, is twice that of isotropic magnets of the same volume and rare earth content. This offers significant advantages in improving motor efficiency, reducing energy consumption, reducing weight, and conserving rare earth resources. This significantly meets the energy-saving and lightweighting needs of automobiles, especially new energy vehicles, and offers broad application prospects in areas such as automobiles, power tools, drones, robots, and smart home appliances. However, NdFeB magnetic materials suffer from a low Curie temperature and poor temperature characteristics, with a coercivity temperature coefficient of approximately -0.55% / °C (25-120°C). Emerging fields such as energy conservation and environmental protection place higher demands on permanent magnet materials, requiring not only high magnetic properties but also high operating temperatures and long-term service stability. Currently, the operating temperature of anisotropic bonded NdFeB magnets does not exceed 100°C, making them difficult to meet the operating temperature requirements (>120°C) required by motors in certain applications. NdFeB permanent magnets are composed of three primary alloy phases: a main phase, an Nd-rich phase, and a B-rich phase. The Nd-rich and B-rich phases in NdFeB permanent magnets are more chemically active than the primary phase and are highly susceptible to oxidation. Furthermore, the significant difference in electrochemical potential between the primary phase and other phases in the magnet makes them susceptible to oxidation or corrosion in high-temperature, humid, and electrochemical environments. This can lead to performance degradation and even failure. Therefore, improving the oxidation and corrosion resistance of rare earth magnetic powders is crucial for the magnet's overall resistance to oxidation and corrosion.

[0004] There are many ways to increase the coercive force and temperature stability, including grain refinement and addition of alloying elements. However, the most effective and commonly used method is to directly add a certain amount of heavy rare earth dysprosium or terbium to the NdFeB alloy material to increase the main phase magnetocrystalline anisotropy field and significantly increase the coercive force of the magnet. However, heavy rare earth resources are scarce and expensive, and at the same time, the remanence and magnetic energy product decrease.

[0005] Patents such as CN1198291C, CN1345073A, and CN1722317A all propose methods for improving the coercive force and temperature stability of magnetic powder by diffusion treatment of anisotropic magnetic powder in HDDR. The general process for preparing magnetic powder is as follows: remove the magnetic powder from the HDDR furnace, mix the magnetic powder with diffusion source powder, and finally return it to the HDDR furnace for high-temperature heat treatment and diffusion. Although the coercive force and temperature stability of the magnetic powder have been improved to varying degrees, the following problems exist: First, the process of removing the magnetic powder from the HDDR furnace and the process of mixing the magnetic powder with the diffusion source powder are both prone to contact with air, causing the oxygen adsorbed on the surface of the magnetic powder to oxidize during the high-temperature diffusion treatment; second, the magnetic powder diffusion heat treatment requires reheating to maintain a high temperature, causing grain growth; third, the residual diffusion source powder that has not been fully diffused is all non-magnetic phase, resulting in a decrease in magnet performance.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of the present invention is to propose a crystal texture type R2Fe 14 B rare earth magnetic powder and its preparation method and apparatus address the existing general process for preparing magnetic powder, which involves removing the magnetic powder from the HDDR furnace, mixing it with diffusion source powder, and finally returning it to the HDDR furnace for high-temperature heat treatment and diffusion. Although the coercivity and temperature stability of the magnetic powder have been improved to varying degrees, the following issues remain: 1. The process of removing the magnetic powder from the HDDR furnace and mixing it with the diffusion source powder both exposes it to air, potentially causing surface oxidation of oxygen adsorbed on the surface of the magnetic powder, which may also oxidize during the high-temperature diffusion treatment; 2. The magnetic powder diffusion heat treatment requires reheating to maintain a high temperature, which causes grain growth; 3. Residual diffusion source powder that has not been fully diffused is a non-magnetic phase, resulting in reduced magnetic performance.

[0008] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0009] A crystal texture type R2Fe 14 B. A method for preparing rare earth magnetic powder, comprising the following steps:

[0010] S1. Preparation of metal vapor: placing the evaporation material in an evaporation chamber and heating the evaporation material under vacuum conditions to evaporate it into metal vapor;

[0011] S2、R2Fe 14 B Magnetic Powder HDDR Preparation: Preparation of R2Fe in HDDR Furnace 14 B magnetic powder, open the middle valve, and pass the metal vapor in the evaporation chamber into the HDDR furnace, directly on the R2Fe 14 A metal layer is deposited on the surface of the B magnetic powder, and a evaporation-grain boundary diffusion heat treatment is carried out simultaneously with the HDDR process at high temperature. After keeping the temperature for 5 to 90 minutes, the heating is stopped, and then the powder is quickly cooled with water or air to 100 to 200 ° C. The anisotropic crystal texture type R2Fe is obtained. 14 B magnetic powder.

[0012] Furthermore, in step S2, R2Fe is prepared in the HDDR furnace using the HDDR process. 14 B magnetic powder, the HDDR process includes hydrogen absorption-disproportionation treatment and dehydrogenation-recombination treatment. After the dehydrogenation-recombination treatment is completed, the intermediate valve is opened to pass the metal vapor in the evaporation chamber into the HDDR furnace.

[0013] Furthermore, in step S2, the metal vapor in the evaporation chamber is introduced into the HDDR furnace, and under the action of the rotation of the HDDR furnace and the stirring plate inside the HDDR furnace, the metal vapor is directly 14 B A uniform metal layer is deposited on the surface of the magnetic powder.

[0014] Furthermore, R is at least one of Nd, Pr, Y, Ce and La.

[0015] Furthermore, the evaporation material is at least one of a single substance of a low-melting-point non-rare earth metal and an alloy of a low-melting-point non-rare earth metal.

[0016] Furthermore, the evaporation material is at least one of a rare earth element and a rare earth alloy.

[0017] Furthermore, the hydrogen absorption-disproportionation treatment comprises the following steps:

[0018] R2Fe 14 B rare earth alloy steel ingot or rare earth alloy rapid solidification casting sheet is placed in the HDDR furnace, and the mechanical pump, Roots pump and diffusion pump are started in sequence to start vacuuming; when the vacuum reaches 10 -2 Then start heating at a heating rate of 5~15℃ / min. When the temperature reaches 200~550℃, fill the furnace with hydrogen at a flow rate of 50~300mL / s and maintain 0.05~0.10MPa for 20~90min; at the same time, continue heating at a rate of 5~15℃ / min; when the temperature reaches 750~850℃, reduce the hydrogen pressure to 0.02~0.06MPa and keep warm for 0.5~5h to complete the hydrogen absorption-disproportionation reaction.

[0019] Furthermore, the dehydrogenation-recombination process comprises the following steps:

[0020] Adjust the temperature of the HDDR furnace to 790~890℃ and slowly remove hydrogen at 100~1000mL / s for 0.5~2h; start the mechanical pump and Roots pump to remove hydrogen to a vacuum degree of 10 -2 , completing the dehydrogenation-recombination process.

[0021] In the second aspect of the present invention, a crystal texture type R2Fe is proposed. 14 B. Preparation device of rare earth magnetic powder, any one of the above-mentioned crystal texture type R2Fe 14 Preparation method of B rare earth magnetic powder using crystal texture type R2Fe 14 B. A preparation device for rare earth magnetic powder, the preparation device comprising:

[0022] An HDDR furnace, wherein the HDDR furnace is in communication with a vacuum system and a gas supply system;

[0023] an evaporation chamber, the evaporation chamber being connected to the HDDR furnace through a connecting pipe, and the evaporation chamber being connected to the vacuum system;

[0024] An intermediate valve is provided on the connecting pipe.

[0025] The third aspect of the present invention is to provide a crystal texture type R2Fe14 B rare earth magnetic powder, the crystal texture type R2Fe 14 B rare earth magnetic powder uses any one of the above crystal texture types R2Fe 14 B is prepared by the preparation method of rare earth magnetic powder.

[0026] Compared with the prior art, the crystal texture type R2Fe 14 B rare earth magnetic powder and its preparation method and device have the following beneficial effects:

[0027] The crystal texture type R2Fe of the present invention 14 B rare earth magnetic powder and its preparation method and device, the metal vapor in the evaporation chamber is passed into the HDDR furnace, directly on the R2Fe 14 A metal layer is deposited on the surface of B magnetic powder, and vapor deposition-grain boundary diffusion heat treatment is carried out simultaneously with the high temperature of the HDDR process, which significantly improves the coercive force, temperature stability and corrosion resistance of the magnetic powder, while reducing the steps of magnetic powder removal and mixing, thereby improving production efficiency. In addition, it can not only avoid the problem of oxygen adsorption on the surface of the magnetic powder during the process of magnetic powder removal and mixing, and oxidation during subsequent high-temperature treatment, but also avoid abnormal grain growth. It has low cost, small equipment investment, and is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A crystal texture type R2Fe described in an embodiment of the present invention 14 B is a schematic structural diagram of a device for preparing rare earth magnetic powder;

[0029] Figure 2 A crystal texture type R2Fe described in an embodiment of the present invention 14 B is a schematic diagram showing the relationship between HDDR process temperature, air pressure and time in the preparation method of rare earth magnetic powder;

[0030] Figure 3 A crystal texture type R2Fe described in the traditional HDDR process 14 B is a schematic diagram showing the relationship between HDDR process temperature, air pressure and time in the preparation method of rare earth magnetic powder;

[0031] Figure 4 This is a demagnetization curve of a bonded magnet prepared by the preparation method described in Comparative Example 2;

[0032] Figure 5 The crystal texture type R2Fe described in Example 2 of the present invention 14 B. Demagnetization curve of bonded magnet prepared by the preparation method of rare earth magnetic powder;

[0033] Figure 6 This is a demagnetization curve of the bonded magnet prepared by the preparation method described in Comparative Example 3.

[0034] Description of reference numerals:

[0035] 1. HDDR furnace; 2. Evaporation chamber; 3. Connecting pipe; 4. Intermediate valve; 5. Vacuum system; 6. Gas supply system. DETAILED DESCRIPTION

[0036] In order to make the technical means, objectives and effects of the present invention easier to understand, embodiments of the present invention are described in detail below with reference to specific figures.

[0037] It should be noted that all terms used in the present invention to indicate direction and position, such as "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "low", "lateral", "longitudinal", "center", etc., are only used to explain the relative positional relationship and connection status between the various components in a certain specific state (as shown in the accompanying drawings). They are only for the convenience of describing the present invention, and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0038] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical connections; direct connections or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0039] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0040] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0041] The conventional process for preparing magnetic powder involves removing the powder from the HDDR furnace, mixing it with diffusion source powder, and then returning it to the HDDR furnace for high-temperature diffusion treatment. While this process improves the coercivity and temperature stability of the powder, it also presents the following challenges: 1. The powder is easily exposed to air during removal from the HDDR furnace and mixing with the diffusion source powder, causing oxygen adsorbed on the powder surface to oxidize during the high-temperature diffusion treatment; 2. The powder diffusion heat treatment requires reheating to maintain high temperatures, which can lead to grain growth; 3. Residual diffusion source powder that has not been fully diffused remains non-magnetic, resulting in reduced magnetic performance.

[0042] Figure 3 A crystal texture type R2Fe described in the traditional HDDR process 14 B Schematic diagram of the relationship between HDDR process temperature, air pressure and time in the preparation method of rare earth magnetic powder.

[0043] In order to solve the above technical problems, the present invention proposes a crystal texture type R2Fe 14 B rare earth magnetic powder preparation method, in the HDDR process directly on the R2Fe 14 The micro-nano deposition layer is deposited in situ on the surface of the B magnetic powder, and the evaporation-grain boundary diffusion heat treatment is carried out simultaneously with the high temperature of the HDDR process, which avoids the magnetic powder from being exposed to air when it is taken out of the HDDR furnace and mixed with the diffusion source powder, thereby preventing the oxygen adsorbed on the surface of the magnetic powder from being oxidized during the high-temperature diffusion treatment; the coercive force and temperature stability of the anisotropic NdFeB magnetic powder are improved, and the service conditions of the motor are expanded; for magnetic powders that only require corrosion resistance, the grain boundary diffusion process is omitted and the R2Fe 14 A low melting point metal layer such as Zn and Al is deposited on the surface of B magnetic powder to improve the corrosion resistance of the magnetic powder.

[0044] Figure 2 A crystal texture type R2Fe described in an embodiment of the present invention 14 B Schematic diagram of the relationship between HDDR process temperature, air pressure and time in the preparation method of rare earth magnetic powder.

[0045] This method can significantly improve the coercivity, temperature stability and corrosion resistance of magnetic powder while reducing the number of steps, improving production efficiency, avoiding magnetic powder oxidation and abnormal grain growth, and has low cost, small equipment investment, and is suitable for mass production.

[0046] The present invention proposes a crystal texture type R2Fe 14 B. A method for preparing rare earth magnetic powder, comprising the following steps:

[0047] The preparation method comprises the following steps:

[0048] S1, metal vapor preparation: placing the evaporation material in the evaporation chamber 2, heating the evaporation material under vacuum conditions to evaporate it at high temperature to form metal vapor;

[0049] S2、R2Fe 14 B Magnetic Powder HDDR Preparation: Preparation of R2Fe in HDDR Furnace 1 14 B magnetic powder, R2Fe prepared using HDDR process in HDDR furnace 1 14 B magnetic powder, HDDR process includes hydrogen absorption-disproportionation treatment and dehydrogenation-recombination treatment. After the dehydrogenation-recombination treatment is completed, when the vacuum degree in HDDR furnace 1 reaches 10 -2 When the middle valve 4 is opened, the metal vapor in the evaporation chamber 2 is passed into the HDDR furnace 1. Under the action of the rotation of the HDDR furnace 1 and the stirring plate inside the HDDR furnace 1, the metal vapor is directly 14 A uniform metal layer is deposited on the surface of the B magnetic powder, and a evaporation-grain boundary diffusion heat treatment is carried out simultaneously with the high temperature of the HDDR process. The temperature in the HDDR furnace 1 is reduced to 700-800°C within 1-4 minutes, and the heating is stopped after 5-90 minutes of heat preservation. Then, the anisotropic crystal texture type R2Fe is obtained by quickly cooling it with water or air to 100-200°C. 14 B magnetic powder.

[0050] Specifically, R is at least one of Nd, Pr, Y, Ce and La.

[0051] Specifically, the evaporation material is at least one of a single substance of a low-melting-point non-rare earth metal and an alloy of a low-melting-point non-rare earth metal, or the evaporation material is at least one of a single substance of a rare earth and a rare earth alloy.

[0052] The low melting point non-rare earth metals mentioned here refer to non-rare earth metals with a melting point of less than 1000°C.

[0053] The low melting point non-rare earth metal element includes at least one of zinc and aluminum.

[0054] The low melting point non-rare earth metal alloy includes at least one of zinc-nickel and zinc-copper.

[0055] The rare earth element includes at least one of dysprosium, terbium, neodymium and praseodymium.

[0056] The rare earth alloy includes at least one of dysprosium-copper, dysprosium-iron, dysprosium-iron-gallium, dysprosium-iron-praseodymium, dysprosium-neodymium-iron-gallium, dysprosium-praseodymium-iron-gallium, neodymium-iron-gallium, neodymium-iron-gallium, neodymium-copper-aluminum, and neodymium-praseodymium-iron-gallium.

[0057] Specifically, in step S1 , the heating method is at least one of resistance heating, electron beam heating, high frequency heating and laser heating.

[0058] Specifically, the hydrogen absorption-disproportionation treatment includes the following steps:

[0059] R2Fe 14 B rare earth alloy steel ingot or rare earth alloy rapid solidification casting sheet is placed in the HDDR furnace, and the mechanical pump, Roots pump and diffusion pump are started in sequence to start vacuuming; when the vacuum reaches 10 -2 Then start heating at a heating rate of 5~15℃ / min. When the temperature reaches 200~550℃, fill the furnace with hydrogen at a flow rate of 50~300mL / s and maintain 0.05~0.10MPa for 20~90min; at the same time, continue heating at a rate of 5~15℃ / min; when the temperature reaches 750~850℃, reduce the hydrogen pressure to 0.02~0.06MPa and keep warm for 0.5~5h to complete the hydrogen absorption-disproportionation reaction.

[0060] Specifically, the dehydrogenation-recombination process includes the following steps:

[0061] Adjust the temperature of HDDR furnace 1 to 790~890℃ and slowly remove hydrogen at 100~1000mL / s for 0.5~2h; start the mechanical pump and Roots pump to remove hydrogen to a vacuum degree of 10 -2 , completing the dehydrogenation-recombination process.

[0062] The second aspect of the present invention, as Figure 1 As shown, a crystal texture type R2Fe is proposed 14 B. Preparation device of rare earth magnetic powder, any one of the above-mentioned crystal texture type R2Fe 14 Preparation method of B rare earth magnetic powder using crystal texture type R2Fe 14 B. A preparation device for rare earth magnetic powder, the preparation device comprising:

[0063] An HDDR furnace 1, wherein the HDDR furnace 1 is connected to a vacuum system 5 and a gas supply system 6;

[0064] an evaporation chamber 2, the evaporation chamber 2 being connected to the HDDR furnace 1 via a connecting pipe 3, and the evaporation chamber 2 being connected to the vacuum system 5;

[0065] An intermediate valve 4 is provided on the connecting pipe 3 .

[0066] The HDDR furnace 1 is rotatable, and a stirring plate is provided inside the HDDR furnace 1 .

[0067] The HDDR furnace 1 includes not only the above-mentioned structure but also other related components. Since the specific structures and assembly relationships of the related components are prior art, they will not be described in detail here.

[0068] The third aspect of the present invention is to provide a crystal texture type R2Fe 14 B rare earth magnetic powder, the crystal texture type R2Fe 14 B rare earth magnetic powder uses any one of the above crystal texture types R2Fe 14 B is prepared by the preparation method of rare earth magnetic powder.

[0069] Example 1

[0070] This embodiment proposes a crystal texture type R2Fe 14 B. A method for preparing rare earth magnetic powder, comprising the following steps:

[0071] S1, metal vapor preparation: placing the evaporation material in the evaporation chamber 2, heating the evaporation material under vacuum conditions to evaporate it at high temperature to form metal vapor;

[0072] S2、R2Fe 14 B Magnetic Powder HDDR Preparation: Preparation of R2Fe in HDDR Furnace 1 14 B magnetic powder, R2Fe prepared using HDDR process in HDDR furnace 1 14 B magnetic powder, HDDR process includes hydrogen absorption-disproportionation treatment and dehydrogenation-recombination treatment. After the dehydrogenation-recombination treatment is completed, when the vacuum degree in HDDR furnace 1 reaches 10 -2 When the air cooling is turned on, the temperature in the HDDR furnace 1 is reduced to 700°C within 3-4 minutes. The intermediate valve 4 is opened to pass the metal vapor in the evaporation chamber 2 into the HDDR furnace 1. Under the action of the rotation of the HDDR furnace 1 and the stirring plate inside the HDDR furnace 1, the HDDR furnace 1 is continuously rotated at a speed of 3r / min, directly in the R2Fe 14 A metal layer is deposited on the surface of the B magnetic powder, and a evaporation-grain boundary diffusion heat treatment is carried out simultaneously with the HDDR process at high temperature. After keeping the temperature for 10 minutes, the heating is stopped, and then the powder is quickly cooled with water or air to 100°C. The anisotropic crystal texture type R2Fe is obtained. 14 B magnetic powder.

[0073] Specifically, in this embodiment, R is Nd.

[0074] Specifically, in this embodiment, the evaporation material is a low-melting-point non-rare earth metal element.

[0075] More specifically, in this embodiment, the evaporation material is zinc element.

[0076] Specifically, in this embodiment, in step S1 , the heating method is resistance heating evaporation.

[0077] Step S1 is as follows: put zinc powder into the evaporation chamber 2, evacuate to 10 -2After 5 Pa, the vacuum system was stopped and resistance heating was turned on to evaporate the zinc powder to form zinc vapor at 950 °C.

[0078] Specifically, the hydrogen absorption-disproportionation treatment includes the following steps:

[0079] Nd 13 Fe 78.7 7nB 0.3 The rare earth alloy steel ingot is placed in the HDDR furnace 1, and the mechanical pump, Roots pump and diffusion pump are started in sequence to start vacuuming; when the vacuum reaches 10 -2 Then start heating; heat at a rate of 10℃ / min. When the temperature reaches 300℃, fill the furnace with hydrogen at a flow rate of 200mL / s and maintain 0.9MPa for 60min, while continuing to heat at a rate of 10℃ / min; when the temperature reaches 820℃, reduce the hydrogen pressure to 0.03MPa and keep warm for 3h to complete the hydrogen absorption-disproportionation reaction.

[0080] Specifically, the dehydrogenation-recombination process includes the following steps:

[0081] Adjust the temperature in HDDR furnace 1 to 830℃ and slowly remove hydrogen at 150mL / s for 1h; start the mechanical pump and Roots pump to quickly remove hydrogen to a vacuum degree of 10 -2 , completing the dehydrogenation-recombination process.

[0082] Example 2

[0083] In this embodiment, different from the embodiment 1,

[0084] Specifically, in this embodiment, R is Nd, Ce, and La.

[0085] Specifically, in this embodiment, the evaporation material is a rare earth element.

[0086] More specifically, in this embodiment, the evaporation material is dysprosium.

[0087] Specifically, in this embodiment, in step S1 , the heating method is electron beam heating.

[0088] Step S1 is as follows: placing dysprosium particles in the evaporation chamber 2, evacuating the chamber to a vacuum of 10 -4 Pa, the vacuum system 5 is stopped and resistance heating is turned on until the dysprosium particles evaporate to form dysprosium vapor.

[0089] Specifically, the hydrogen absorption-disproportionation treatment includes the following steps:

[0090] Nd 8.8 5L 0.2 Fe 76.7 B7Nb 0.3The rare earth alloy steel ingot or rare earth alloy rapid solidification casting sheet is placed in the HDDR furnace 1, and the mechanical pump, Roots pump and diffusion pump are started in sequence to start vacuuming; when the vacuum reaches 10 -2 Then start heating; heat at a rate of 8°C / min. When the temperature reaches 250°C, fill the furnace with hydrogen at a flow rate of 150mL / s and maintain 0.9MPa for 40min, while continuing to heat at a rate of 10°C / min; when the temperature reaches 800°C, reduce the hydrogen pressure to 0.04MPa and keep warm for 3h to complete the hydrogen absorption-disproportionation reaction.

[0091] Specifically, the dehydrogenation-recombination process includes the following steps:

[0092] Adjust the temperature of HDDR furnace 1 to 840℃ and slowly remove hydrogen at 150mL / s for 1h; start the mechanical pump and Roots pump to quickly remove hydrogen to a vacuum degree of 10 -2 , completing the dehydrogenation-recombination process.

[0093] Specifically, step S2 is as follows: preparing R2Fe in HDDR furnace 1 14 B magnetic powder, R2Fe prepared using HDDR process in HDDR furnace 1 14 B magnetic powder, HDDR process includes hydrogen absorption-disproportionation treatment and dehydrogenation-recombination treatment. After the dehydrogenation-recombination treatment is completed, when the vacuum degree in HDDR furnace 1 reaches 10 -2 When the air cooling is turned on, the temperature in the HDDR furnace 1 is reduced to 800°C within 1-2 minutes. The intermediate valve 4 is opened to pass the metal vapor in the evaporation chamber 2 into the HDDR furnace 1. Under the action of the rotation of the HDDR furnace 1 and the stirring plate inside the HDDR furnace 1, the HDDR furnace 1 continues to rotate at a speed of 4r / min, directly in the R2Fe 14 A metal layer is deposited on the surface of the B magnetic powder, and a evaporation-grain boundary diffusion heat treatment is carried out simultaneously with the HDDR process at high temperature. After keeping the temperature for 60 minutes, the heating is stopped, and then the powder is quickly cooled with water or air to 200°C. The anisotropic crystal texture type R2Fe is obtained. 14 B magnetic powder.

[0094] Comparative Example 1

[0095] Compared with Example 1, the difference is that step S1 is not included. In step S2, R2Fe is prepared in the HDDR furnace 1 using the HDDR process. 14 B magnetic powder, does not pass the metal vapor in the evaporation chamber 2 into the HDDR furnace 1.

[0096] Comparative Example 2

[0097] Compared with Example 2, the difference is that step S1 is not included. In step S2, R2Fe is prepared in the HDDR furnace 1 using the HDDR process. 14 B magnetic powder, does not pass the metal vapor in the evaporation chamber 2 into the HDDR furnace 1.

[0098] Comparative Example 3

[0099] Compared with Example 1, the difference is that

[0100] Step S2 is specifically as follows:

[0101] R2Fe 14 B. Preparation of magnetic powder HDDR: R2Fe is prepared using the HDDR process in HDDR furnace 1 14 B magnetic powder, HDDR process includes hydrogen absorption-disproportionation treatment and dehydrogenation-recombination treatment. After the dehydrogenation-recombination treatment is completed, the anisotropic R2Fe 14 The magnetic powder B is taken out from the HDDR furnace 1, mixed with the metal vapor in the evaporation chamber 2, and finally returned to the HDDR furnace 1 for high-temperature heat treatment and diffusion.

[0102] Performance Testing

[0103] The anisotropic R2Fe prepared in Comparative Example 2 14 B magnetic powder was prepared into molded bonded magnet under 2.0T magnetic field orientation and demagnetization test was carried out. The results are shown in Figure 4 ; Anisotropic R2Fe prepared in Example 2 14 B magnetic powder was prepared into molded bonded magnet under 2.0T magnetic field orientation and demagnetization test was carried out. The results are shown in Figure 5 ; Anisotropic R2Fe prepared in Comparative Example 3 14 B magnetic powder was prepared into molded bonded magnet under 2.0T magnetic field orientation and demagnetization test was carried out. The results are shown in Figure 6 The anisotropic R2Fe prepared in Examples 1-2 and Comparative Examples 1-3 14 The B magnetic powder was prepared into a molded bonded magnet under a 2.0T magnetic field orientation and the performance test was carried out. The results are shown in Table 1.

[0104] Table 1 Properties of anisotropic NdFeB bonded magnets

[0105]

[0106] As shown in Table 1, the R2Fe prepared in Examples 1 and 2 14 B magnetic powder, significantly improves the coercivity, temperature stability and corrosion resistance of magnetic powder.

[0107] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A crystal texture type R2Fe 14 B. A method for preparing rare earth magnetic powder, characterized in that: The preparation method comprises the following steps: S1. Preparation of metal vapor: placing the evaporation material in the evaporation chamber (2), and heating the evaporation material under vacuum conditions to evaporate it to form metal vapor; S2、R2Fe 14 B. Preparation of magnetic powder HDDR: Preparation of R2Fe in HDDR furnace (1) 14 B magnetic powder, open the middle valve (4), pass the metal vapor in the evaporation chamber (2) into the HDDR furnace (1), and directly 14 A metal layer is deposited on the surface of the B magnetic powder, and a evaporation-grain boundary diffusion heat treatment is carried out simultaneously with the HDDR process at high temperature. After holding the temperature for 5 to 90 minutes, the heating is stopped, and then the powder is quickly cooled with water or air to 100 to 200 ° C. The anisotropic crystal texture type R2Fe is obtained. 14 B magnetic powder.

2. A crystal texture type R2Fe according to claim 1 14 B. A method for preparing rare earth magnetic powder, characterized in that: In step S2, R2Fe is prepared using the HDDR process in the HDDR furnace (1). 14 B magnetic powder, the HDDR process includes hydrogen absorption-disproportionation treatment and dehydrogenation-recombination treatment. After the dehydrogenation-recombination treatment is completed, the intermediate valve (4) is opened to pass the metal vapor in the evaporation chamber (2) into the HDDR furnace (1).

3. A crystal texture type R2Fe according to claim 2 14 B. A method for preparing rare earth magnetic powder, characterized in that: In step S2, the metal vapor in the evaporation chamber (2) is introduced into the HDDR furnace (1), and under the action of the rotation of the HDDR furnace (1) and the stirring plate inside the HDDR furnace (1), the metal vapor is directly 14 B A uniform metal layer is deposited on the surface of the magnetic powder.

4. A crystal texture type R2Fe according to claim 1 14 B. A method for preparing rare earth magnetic powder, characterized in that: R is at least one of Nd, Pr, Y, Ce and La elements.

5. The crystal texture type R2Fe according to claim 1 14 B. A method for preparing rare earth magnetic powder, characterized in that: The vapor deposition material is at least one of a single substance of a low-melting-point non-rare earth metal and an alloy of a low-melting-point non-rare earth metal.

6. A crystal texture type R2Fe according to claim 1 14 B. A method for preparing rare earth magnetic powder, characterized in that: The evaporation material is at least one of a rare earth element and a rare earth alloy.

7. The crystal texture type R2Fe according to claim 2 14 B. A method for preparing rare earth magnetic powder, characterized in that: The hydrogen absorption-disproportionation treatment comprises the following steps: R2Fe 14 B rare earth alloy steel ingot or rare earth alloy rapid solidification casting sheet is placed in HDDR furnace (1), and mechanical pump, Roots pump and diffusion pump are started in sequence to start vacuuming; when the vacuum reaches 10 -2 Then start heating at a heating rate of 5~15℃ / min. When the temperature reaches 200~550℃, fill the furnace with hydrogen at a flow rate of 50~300mL / s and maintain 0.05~0.10MPa for 20~90min; at the same time, continue heating at a rate of 5~15℃ / min; when the temperature reaches 750~850℃, reduce the hydrogen pressure to 0.02~0.06MPa and keep warm for 0.5~5h to complete the hydrogen absorption-disproportionation reaction.

8. The crystal texture type R2Fe according to claim 2 14 B. A method for preparing rare earth magnetic powder, characterized in that: The dehydrogenation-recombination process comprises the following steps: Adjust the temperature of the HDDR furnace (1) to 790~890℃ and slowly remove hydrogen at 100~1000mL / s for 0.5~2h; start the mechanical pump and Roots pump to remove hydrogen to a vacuum degree of 10 -2 , completing the dehydrogenation-recombination process.

9. A crystal texture type R2Fe 14 B. A device for preparing rare earth magnetic powder, characterized in that: A crystal texture type R2Fe according to any one of claims 1 to 8 14 Preparation method of B rare earth magnetic powder using crystal texture type R2Fe 14 B. A preparation device for rare earth magnetic powder, the preparation device comprising: An HDDR furnace (1), the HDDR furnace (1) being in communication with a vacuum system (5) and a gas supply system (6); an evaporation chamber (2), the evaporation chamber (2) being in communication with the HDDR furnace (1) via a communication pipe (3), and the evaporation chamber (2) being in communication with the vacuum system (5); An intermediate valve (4), wherein the intermediate valve (4) is arranged on the connecting pipe (3).

10. A crystal texture type R2Fe 14 B rare earth magnetic powder, characterized in that The crystal texture type R2Fe 14 B rare earth magnetic powder uses a crystal texture type R2Fe according to any one of claims 1 to 8 14 B is prepared by the preparation method of rare earth magnetic powder.

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