Large-size rare earth permanent magnet material and preparation method thereof

Abstract

The application discloses a large-size rare earth permanent magnet material and a preparation method thereof. The preparation method of the large-size rare earth permanent magnet material comprises the following specific steps: pretreating a base magnet blank; performing sputtering treatment on the pretreated magnet; and performing heat treatment on the magnet after the sputtering treatment to obtain the required rare earth permanent magnet material. The application provides a batch preparation method suitable for large-size (width greater than 20 mm) sintered neodymium-iron-boron permeation. The application is used to improve the magnet performance, on one hand, the product performance can be effectively improved (compared with the base magnet blank, the coercive force is increased by 6930Oe-9990Oe, and the remanence is reduced by 220Gs-340Gs), on the other hand, the batch product with qualified appearance and meeting the performance requirements can be output, and the burr defects of the large-size product can be avoided.

Description

Technical Field

[0001] This invention belongs to the field of rare earth permanent magnet materials technology, and specifically relates to a large-size rare earth permanent magnet material and its preparation method. Background Technology

[0002] Sintered NdFeB magnets, due to their excellent magnetic properties, are widely used in consumer electronics, industrial motors, audio speakers, and automotive motors. With the development of rare-earth permanent magnet materials, they have become essential basic functional materials for modern technological development and industrial manufacturing. The construction of manufacturing innovation centers, intelligent manufacturing projects, industrial foundation strengthening projects, green manufacturing projects, and high-end equipment innovation projects all rely on rare-earth permanent magnet materials. With the global development of new energy vehicles, automotive motors are increasingly widely used due to their small size, light weight, high power density, high reliability, and high speed regulation accuracy. Permanent magnet synchronous motors have the highest power density, with an efficiency of up to 97%, enabling them to provide maximum power and acceleration to vehicles. Therefore, they are mainly used in new energy passenger vehicles with the highest requirements for energy-to-volume ratio. The current development direction of new energy vehicle drive motors includes the following aspects: miniaturization and lightweight design, high efficiency, superior torque characteristics, long service life, high reliability, low noise, and low price. As time goes by, new energy drive motors are showing a trend towards permanent magnet motors: permanent magnet motors have advantages such as high torque density, high power density, high efficiency, and high reliability.

[0003] The performance grades of sintered NdFeB products used in automotive motors are mainly UH and EH. Currently, UH and EH products have a high content of heavy rare earth elements, while the soaring price of rare earth raw materials significantly impacts motor costs. This contradicts the market demand for lower heavy rare earth content. Grain boundary diffusion can achieve the goal of improving product performance with a small amount of heavy rare earth elements, and is a commonly used cost-effective preparation method. Grain boundary diffusion mainly involves coating, deposition, and sputtering to coat the magnet surface with metal powder or composites. Subsequent high-temperature heat treatment allows heavy rare earth (Tb / Dy) elements to enter the main phase of the sintered magnet through grain boundaries. This process significantly improves the coercivity of the product, but it also alters the material's microstructure and the product's appearance. For products with larger dimensions, such as a width of 20mm or more, when the magnet is placed on a grid-like support, the high temperature of the heat treatment causes the vapor of heavy rare earth elements to react with the grain boundaries, resulting in the grain boundaries being in a molten state. In addition, the product itself has a relatively large weight, and the Nd-rich phase at the contact point is prone to creating pits at the grid contact point, which increases the defect rate of the product's appearance.

[0004] Currently, most research institutions and individuals report on reducing contact between the product and heavy rare earth plates during infiltration heat treatment, thereby reducing the presence of pitting. Patent CN103646772A discloses a method for preparing R-Fe-B sintered magnets, where zirconium oxide, silicon dioxide, or alumina powder is placed between the dysprosium plate and the magnet to ensure no contact and avoid pitting or poor appearance. However, because dysprosium metal is easily softened, high-melting-point particles can easily enter the dysprosium plate, reducing the evaporation concentration of dysprosium, decreasing the infiltration effect, and increasing costs. Patent CN103646773A discloses a method for manufacturing R-Fe-B type sintered magnets, where rare earth element oxides are placed between the magnet and the heavy rare earth plate to prevent contact and reduce appearance defects. This method achieves non-direct contact between the magnet and the heavy rare earth plate and avoids excessive evaporation of heavy rare earth vapors; however, the effect of rare earth oxides on improving the coercivity of the product is much weaker, reducing the infiltration effect. Patent CN106128678B discloses a method for preparing RTB rare-earth permanent magnets. This method involves coating the magnet surface with a rare-earth hydride, rare-earth fluoride, or rare-earth oxide or composite to form a thin film. During high-temperature processing, this film avoids surface contact pitting and excessive penetration, which could affect the product's remanence. However, this method is relatively complex to operate, and mass production requires a long preparation time and is inefficient.

[0005] As can be seen from the above patents: Although the grain boundary diffusion treatment technology can significantly improve coercivity by adding a small amount of heavy rare earth elements, reduce pitting, and reduce product production costs, it is a market-demanded and competitive preparation process, especially suitable for automotive motor magnets; however, in actual production, there are still some problems that need to be solved: (1) Large-sized products have long penetration times and high product weight, and the pitting phenomenon still exists in the products after heat treatment in mass production. (2) The current effective process to avoid pitting is to form a thin film on the product surface to avoid contact between the product surface and the heavy rare earth support, but the preparation process is complex and costly, and it is not suitable for mass production. (3) When the content of (Al+Cu) in the basic composition of the magnet is high, the (Al+Cu) alloying elements are normally distributed in the Nd-rich phase between grains, and at the same time distributed along the grain boundary, wrapping the main phase, improving the wettability between the main phase and the Nd-rich phase, optimizing the grain boundary to improve coercivity. However, during the permeation process, the presence of (Al+Cu) elements acts as a barrier in the diffusion channels, hindering the effective entry of heavy rare earth elements. Consequently, under the same permeation conditions, the permeation rate of heavy rare earth elements decreases with increasing (Al+Cu) content. The advantages of the permeation process are not fully realized, leading to a decline in product competitiveness.

[0006] Therefore, there is an urgent need to provide a method for preparing large-size rare earth permanent magnet materials, which can solve at least one of the three problems mentioned above in actual production. Summary of the Invention

[0007] To address the above problems, the purpose of this invention is to provide a large-size rare-earth permanent magnet material and its preparation method.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] This invention discloses a method for preparing large-size rare-earth permanent magnet materials, the specific steps of which are as follows:

[0010] Pre-process the basic magnet blank;

[0011] The pretreated magnet is then subjected to sputtering.

[0012] The sputtered magnets are then subjected to heat treatment to obtain the desired rare earth permanent magnet material.

[0013] Preferably, the specific process for pre-processing the basic magnet blank is as follows:

[0014] Preparation of basic magnet blanks;

[0015] The basic magnet blank is machined to obtain a basic magnet of the required size;

[0016] Clean the base magnet.

[0017] Preferably, the preparation of the basic magnet blank adopts a low-oxygen process, and the sum of the contents of Al and Cu in the basic magnet blank is less than 0.4 wt%.

[0018] Preferably, the specific process for cleaning the basic magnet is as follows: the basic magnet to be treated is immersed in a degreasing agent to remove the oil stains on the surface of the magnet, then the surface is washed with clean water, then acid-washed with HNO3 solution, then ultrasonically washed, and finally dried quickly with strong air.

[0019] Preferably, the base magnet to be treated is immersed in the degreasing agent for 8-12 minutes, pickled with HNO3 for 20-40 seconds, and ultrasonically washed for 20-40 seconds.

[0020] Preferably, the specific conditions for the sputtering process are as follows: a composite metal target is used as the sputtering source, sputtering is performed at a voltage of 28-35V for 30-70 minutes, double-sided sputtering is achieved by flipping the target, and the vacuum degree during the sputtering process is 0.13Pa.

[0021] Preferably, the preparation process of the composite metal target is as follows:

[0022] According to H 100-x-y M x Q y The chemical formula is used to smelt the target material using a vacuum intermediate frequency induction method, with a vacuum degree of not less than 10 during smelting. -2 Pa, the composite metal target has a thickness of 0.5-3mm, a length of 200-300mm, and a width of 100-240mm, where H is Tb; M is any one of Nd, Pr, and NdPr; Q is any one or two of Cu, Al, Zn, and Sn; 0≤x≤20; 0≤y≤20.

[0023] Preferably, the specific process of heat-treating the sputtered magnet to obtain the desired rare-earth permanent magnet material is as follows:

[0024] After sputtering, the magnet is placed in a material box, and a high-temperature resistant thin ceramic plate with a thickness of 3-5mm is placed at the bottom of the material box. The heat treatment temperature is divided into two stages: first, it is treated at 600-900℃ for 25-35 hours; then, it is tempered at 400-600℃ for 3-15 hours to obtain the desired rare earth permanent magnet material.

[0025] The present invention also discloses a rare earth permanent magnet material prepared by the above-mentioned method for preparing large-size rare earth permanent magnet materials.

[0026] Preferably, the rare earth permanent magnet material has a coercivity increased by 6930-9990 Oe and a remanence decreased by 220-340 Gs compared to the basic magnet blank.

[0027] Preferably, the chemical formula of the basic magnet blank is (PrNd). 31.5-m Dy m (Cu + Al) n Fe bal In B1, m and n are the mass percentages of the corresponding elements, and 0 < m ≤ 4, 0 < n ≤ 0.4. The terbium content in the rare earth permanent magnet material is 0.6 wt%.

[0028] The beneficial effects of this invention are as follows:

[0029] The basic magnet blank in this invention uses a low (Al+Cu) content. Due to the distribution of Al+Cu elements in the Nd-rich phase, the higher the content, the better the wettability between the main phase and the Nd-rich phase, and the more difficult it is to form a permeation coating layer around the main phase. During the subsequent high-temperature diffusion process, some of the permeated Tb will seep out along the grain boundary phase according to the concentration balance relationship. When there is a hard support material on the surface, it is easier to bond with the surface of the support material. During cooling, the shrinkage part of the magnet sticks to the support material, forming pits. Therefore, the low (Al+Cu) content basic magnet blank can eliminate some of the factors that cause pit formation.

[0030] In this invention, a high-temperature resistant thin magnetic plate is placed between the magnet and the material box during the infiltration heat treatment process. This ensures that heavy rare earth elements can fully enter the magnet grain boundaries during infiltration and form a thin layer around the main phase to improve coercivity. On the other hand, it prevents the melting points of the infiltrated product from contacting each other during long-term heat treatment and prevents pitting from forming after cooling, thereby improving the pass rate of the infiltrated product.

[0031] The evaporation source material of this invention is a composite metal target formed by terbium, a heavy rare earth element, through smelting technology with one or two of the light rare earth elements Nd, Pr, or other auxiliary metals such as Zn and Sn. The composite metal target is made of substances with different melting points. Due to the different magnitudes of the interparticle forces within the substances, the overall internal energy of the metal increases, resulting in a lower melting point. This makes the composite metal target have a lower evaporation temperature compared to pure metal targets.

[0032] In summary, this invention provides a method suitable for mass production of rare earth large-size (width over 20mm) sintered NdFeB infiltration magnets. Using this invention to improve magnet performance effectively enhances product performance (coercivity increased by 6930Oe-9990Oe and remanence reduced by 220Gs-340Gs compared to the basic magnet blank); furthermore, it avoids pitting defects common in large-size products, resulting in mass-produced products with acceptable appearance and performance.

[0033] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This diagram shows the internal stacking of the material box during the heat treatment stage of the present invention.

[0036] Figure 2 A process route diagram of the present invention is shown;

[0037] Figure 3 A performance variation comparison graph of Embodiment 1 of the present invention is shown;

[0038] In the attached diagram, 1-pre-treated magnet, 2-high temperature resistant thin ceramic plate, 3-material box. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] like Figure 2 As shown, this invention discloses a method for preparing large-size rare-earth permanent magnet materials, the specific steps of which are as follows:

[0041] Pre-process the basic magnet blank;

[0042] The pretreated magnet is then subjected to sputtering.

[0043] The sputtered magnets are then subjected to heat treatment to obtain the desired rare earth permanent magnet material.

[0044] Preferably, the specific process for pre-processing the basic magnet blank is as follows:

[0045] Prepare basic magnet blanks with low sum of Al and Cu content;

[0046] The basic magnet blank is machined to obtain a basic magnet of the required size (width not less than 20mm, orientation dimension between 2-10mm);

[0047] Clean the base magnet.

[0048] Preferably, the preparation of the basic magnet blank adopts a low-oxygen process (specifically, the blank preparation process includes melting, hydrogen breaking, air jet milling, molding and sintering, etc. Preferably, the oxygen supplementation in the air jet milling stage is reduced during preparation to reduce the oxygen content of the blank, and the oxygen content of the blank is controlled at about 1200 ppm), and the sum of Al and Cu content in the basic magnet blank is less than 0.4 wt%.

[0049] Preferably, the specific process for cleaning the basic magnet is as follows: the basic magnet to be treated is immersed in a degreasing agent to remove the oil stains on the surface of the magnet, then the surface is washed with clean water, then acid-washed with HNO3 solution, then ultrasonically washed, and finally dried quickly with strong air.

[0050] Preferably, the base magnet to be treated is immersed in the degreasing agent for 8-12 minutes, acid-washed with HNO3 solution for 20-40 seconds (preferably, HNO3 is a weak nitric acid with a mass concentration of 3%), and ultrasonically washed with water for 20-40 seconds.

[0051] Preferably, the specific conditions for the sputtering process are as follows: a composite metal target is used as the sputtering source, sputtering is performed at a voltage of 28-35V for 30-70 minutes, double-sided sputtering is achieved by flipping the target, and the vacuum degree during the sputtering process is 0.13Pa.

[0052] Preferably, the preparation process of the composite metal target is as follows:

[0053] According to H 100-x-y M x Q y The chemical formula is used to smelt the target material using a vacuum intermediate frequency induction method, with a vacuum degree of not less than 10 during smelting. -2 Pa, the composite metal target has a thickness of 0.5-3mm, a length of 200-300mm, and a width of 100-240mm, where H is Tb; M is any one of Nd, Pr, and NdPr; Q is any one or two of Cu, Al, Zn, and Sn; 0≤x≤20; 0≤y≤20.

[0054] Preferably, the specific process of heat-treating the sputtered magnet to obtain the desired rare-earth permanent magnet material is as follows:

[0055] After sputtering, the magnets are placed in a specially designed material box made of molybdenum. A high-temperature resistant thin ceramic plate (purchased directly from the market, preferably 3-5mm thick) is placed at the bottom of the box. The arrangement is illustrated in the diagram below. Figure 1As shown, the heat treatment temperature is divided into two stages: first, it is treated at 600-900℃ for 25-35 hours; then, it is tempered at 400-600℃ for 3-15 hours to obtain the desired rare earth permanent magnet material.

[0056] The present invention also discloses a rare earth permanent magnet material prepared by the above-mentioned method for preparing large-size rare earth permanent magnet materials.

[0057] Preferably, the rare earth permanent magnet material has a higher coercivity (6930 Oe-9990 Oe) and a lower remanence (220 Gs-340 Gs) compared to the basic magnet blank.

[0058] Preferably, the chemical formula of the basic magnet blank is (PrNd). 31.5-m Dy m (Cu + Al) n Fe bal In B1, m and n are the mass percentages of the corresponding elements, and 0 < m ≤ 4, 0 < n ≤ 0.4. The terbium content in the rare earth permanent magnet material is 0.6 wt%.

[0059] As can be seen from the above, in this invention, the (Al+Cu) content in the basic magnet blank is controlled below 0.4wt%, and it is processed into a large-size product (width above 20mm). A composite metal target is used as the sputtering source, and sputtering is performed at 28-35V for 30-70 minutes. Double-sided sputtering is achieved by flipping the target. This invention uses composite target sputtering, sputtering penetration is performed on two surfaces perpendicular to the magnet's easy magnetization direction, and a metal film is deposited on the surface of the NdFeB magnet. After sputtering, the magnet is placed in a material box made of molybdenum, and a thin high-temperature resistant ceramic plate is placed inside the box. The arrangement diagram is shown below. Figure 1 As shown. Finally, infiltration heat treatment is performed at a medium-high temperature of 650-900℃, followed by low-temperature treatment at 400-600℃. By adjusting the sputtering time and heat treatment time, the heavy rare earth elements and auxiliary metals diffuse into the magnet through the grain boundaries. The heavy rare earth elements and Nd2Fe at the main phase edge are also involved. 14 Nd in B undergoes a substitution reaction to form (NdTb)₂Fe, which has high anisotropy. 14 Phase B suppresses the growth of demagnetizing domain nuclei during demagnetization, thereby increasing the magnet's coercivity by 6930 Oe-9990 Oe and reducing remanence by 220 Gs-340 Gs while maintaining the appearance of large-sized products. This improves the product's appearance qualification rate, resulting in a pitted finish.

[0060] The present invention will be further illustrated below with reference to examples. The embodiments of the present invention are only for illustrating the present invention and are not intended to limit the present invention.

[0061] Example 1

[0062] A method for preparing large-size rare-earth permanent magnet materials, the specific steps of which are as follows:

[0063] 1. Prepare a basic magnet blank with low (Al+Cu) content: (Al+Cu) content is 0.23wt%, Dy (dysprosium) content is 1.3%, and the corresponding elemental composition ratio is (PrNd). 30.2 Dy 1.3 Cu 0.11 Al 0.12 Fe bal B1 is prepared using a low-oxygen process, with a Br content of 14.08 kGs and a coercivity of 18.38 kGs in the basic magnet blank.

[0064] 2. Machining the basic magnet blank to produce a product with dimensions of 32*21*6mm and a magnet penetration direction of 6mm.

[0065] 3. Immerse the magnet in a degreasing agent for 10 minutes to remove oil stains from its surface. Rinse the surface with clean water, then acid-wash with HNO3 for about 30 seconds, followed by water washing and ultrasonic treatment for 30 seconds, and finally rapid drying with strong airflow.

[0066] 4. Place the magnet in the sputtering furnace and sputter the two orientation surfaces of the magnet. The sputtering voltage is 30V, the vacuum degree is 0.13Pa, and the sputtering time is 50min.

[0067] A composite metal target is used as the sputtering source during sputtering. The preparation process of the composite metal target is as follows:

[0068] According to H 100-x-y M x Q y The chemical formula is used to smelt the target material using a vacuum intermediate frequency induction method, with a vacuum degree of not less than 10 during smelting. -2 Pa, the composite metal target has a thickness of 0.5-3mm, a length of 200-300mm, and a width of 100-240mm, where H is Tb; M is any one of Nd, Pr, and NdPr; Q is any one or two of Cu, Al, Zn, and Sn; 0≤x≤20; 0≤y≤20, for example, it can be Tb, Tb 60 Nd 20 Cu 20 、Tb 60 Pr 20 Al 20 、Tb 60 Pr 20 Zn 20 、Tb 50 Pr 25 Sn25 One of them, where x and y are weight percentages.

[0069] 5. After sputtering, the magnet is placed in a special material box (the material box is made of molybdenum). A high-temperature resistant thin ceramic plate is placed at the bottom of the material box. The heat treatment parameters are 900℃ for 25 hours. The magnet is then cooled to no more than 60℃ in the furnace, and then heated to 450℃. The magnet is held at 450℃ for 15 hours (preferably, the heating rate is 5℃ / minute and the cooling rate is 6℃ / minute) to obtain the desired rare earth permanent magnet material. From the photograph of the desired rare earth permanent magnet material, it can be seen that the rare earth permanent magnet material obtained by the method of the present invention has no pits on its surface.

[0070] 6. The infiltrated magnet was directly tested using the Metis BH curve. The magnet's coercivity increased by 8550 Oe, while the remanence decreased slightly by 290 Gs. The curve is shown below. Figure 3 As shown in Table 1, the changes in magnet performance before and after dysprosium infiltration are as follows.

[0071] Example 2

[0072] A method for preparing large-size rare-earth permanent magnet materials, the specific steps of which are as follows:

[0073] 1. Prepare a basic magnet blank with low (Al+Cu) content, with an (Al+Cu) content of 0.3wt% and a Dy content of 4%, corresponding to an elemental composition ratio of (PrNd). 27.5 Dy4Cu 0.13 Al 0.17 Fe bal B 1.0 The preparation process is a low-oxygen process, with the Br content of the basic magnet blank being 13.34 kGs and the coercivity being 24.65 kOe.

[0074] 2. Machining the basic magnet blank to produce a product with dimensions of 25*21*8mm and a magnet penetration direction of 8mm.

[0075] 3. Immerse the magnet in a degreasing agent for 10 minutes to remove oil stains from its surface. Rinse the surface with clean water, then acid-wash with HNO3 for about 30 seconds, followed by water washing and ultrasonic treatment for 30 seconds, and finally rapid drying with strong airflow.

[0076] 4. Place the magnet in the sputtering furnace and sputter the two orientation surfaces of the magnet. The sputtering voltage is 30V, the vacuum degree is 0.13Pa, and the sputtering time is 50min.

[0077] A composite metal target is used as the sputtering source during sputtering. The preparation process of the composite metal target is as follows:

[0078] According to H 100-x-y Mx Q y The chemical formula is used to smelt the target material using a vacuum intermediate frequency induction method, with a vacuum degree of not less than 10 during smelting. -2 Pa, the composite metal target has a thickness of 0.5-3mm, a length of 200-300mm, and a width of 100-240mm, where H is Tb; M is any one of Nd, Pr, and NdPr; Q is any one or two of Cu, Al, Zn, and Sn; 0≤x≤20; 0≤y≤20, for example, it can be Tb, Tb 60 Nd 20 Cu 20 、Tb 60 Pr 20 Al 20 、Tb 60 Pr 20 Zn 20 、Tb 50 Pr 25 Sn 25 One of them, where x and y are weight percentages.

[0079] 5. After sputtering, the magnet is placed in a special material box with a high-temperature resistant thin ceramic plate at the bottom. The heat treatment parameters are 900℃ for 25 hours; then cooled to 60℃ in the furnace, and then heated to 450℃ and held at 450℃ for 15 hours.

[0080] 6. The BH curve of the magnet after dysprosium infiltration was directly tested using Metis. The coercivity of the magnet increased by 6930 Oe, while the remanence decreased slightly by 280 Gs. The changes in magnet performance before and after dysprosium infiltration are shown in Table 1.

[0081] Example 3

[0082] A method for preparing large-size rare-earth permanent magnet materials, the specific steps of which are as follows:

[0083] 1. Prepare a basic magnet blank with low (Al+Cu) content, with an (Al+Cu) content of 0.35wt% and a Dy content of 3.2%, corresponding to an elemental composition ratio of (PrNd). 28.3 Dy 3.2 Cu 0.12 Al 0.23 Fe bal B 1.0 The preparation process is a low-oxygen process, with the Br content of the basic magnet blank being 13.07 kGs and the coercivity being 22.89 kOe.

[0084] 2. Machining the basic magnet blank to produce a product with dimensions of 31*25*4.2mm and a magnet penetration direction of 4.2mm.

[0085] 3. Immerse the magnet in degreasing agent for 10 minutes to remove oil stains from the magnet surface. After rinsing the surface with water, acid-wash with HNO3 for about 30 seconds, then rinse with water and ultrasonically treat for 30 seconds, and finally dry quickly with strong air.

[0086] 4. Place the magnet in the sputtering furnace and sputter the two orientation surfaces of the magnet. The sputtering voltage is 30V, the vacuum degree is 0.13Pa, and the sputtering time is 35min.

[0087] A composite metal target is used as the sputtering source during sputtering. The preparation process of the composite metal target is as follows:

[0088] According to H 100-x-y M x Q y The chemical formula is used to smelt the target material using a vacuum intermediate frequency induction method, with a vacuum degree of not less than 10 during smelting. -2 Pa, the composite metal target has a thickness of 0.5-3mm, a length of 200-300mm, and a width of 100-240mm, where H is Tb; M is any one of Nd, Pr, and NdPr; Q is any one or two of Cu, Al, Zn, and Sn; 0≤x≤20; 0≤y≤20. For example, it can be Tb, Tb 60 Nd 20 Cu 20 、Tb 60 Pr 20 Al 20 、Tb 60 Pr 20 Zn 20 、Tb 50 Pr 25 Sn 25 One of them, where x and y are weight percentages.

[0089] 5. After sputtering, the magnet is placed in a special material box with a high-temperature resistant thin ceramic plate at the bottom. The heat treatment parameters are 900℃ for 25 hours; then cooled to 60℃ in the furnace, and then heated to 450℃ and held at 450℃ for 15 hours.

[0090] 6. The BH curve of the magnet after dysprosium infiltration was directly tested by Metis. The coercivity of the magnet increased by 7660 Oe, while the remanence decreased slightly by 300 Gs. The changes in magnet performance before and after dysprosium infiltration are shown in Table 1.

[0091] Example 4

[0092] A method for preparing large-size rare-earth permanent magnet materials, the specific steps of which are as follows:

[0093] 1. Prepare a basic magnet blank with low (Al+Cu) content, with an (Al+Cu) content of 0.35wt% and a Dy content of 3.2%, corresponding to an elemental composition ratio of (PrNd). 28.3 Dy 3.2 Cu 0.12 Al 0.23 Fe bal B 1.0 The preparation process is a low-oxygen process, with the Br content of the basic magnet blank being 13.07 kGs and the coercivity being 22.89 kOe.

[0094] 2. Machining the basic magnet blank to produce a product with dimensions of 31*25*6mm and a magnet penetration direction of 6mm.

[0095] 3. Immerse the magnet in a degreasing agent for 10 minutes to remove oil stains from its surface. Rinse the surface with clean water, then acid-wash with HNO3 for about 30 seconds, followed by water washing and ultrasonic treatment for 30 seconds, and finally rapid drying with strong airflow.

[0096] 4. Place the magnet in the sputtering furnace and sputter the two orientation surfaces of the magnet. The sputtering voltage is 30V, the vacuum degree is 0.13Pa, and the sputtering time is 35min.

[0097] A composite metal target is used as the sputtering source during sputtering. The preparation process of the composite metal target is as follows:

[0098] According to H 100-x-y M x Q y The chemical formula is used to smelt the target material using a vacuum intermediate frequency induction method, with a vacuum degree of not less than 10 during smelting. -2 Pa, the composite metal target has a thickness of 0.5-3mm, a length of 200-300mm, and a width of 100-240mm, where H is Tb; M is any one of Nd, Pr, and NdPr; Q is any one or two of Cu, Al, Zn, and Sn; 0≤x≤20; 0≤y≤20. For example, it can be Tb, Tb 60 Nd 20 Cu 20 、Tb 60 Pr 20 Al 20 、Tb 60 Pr 20 Zn 20 、Tb 50 Pr 25 Sn 25 One of them, where x and y are weight percentages.

[0099] 5. After sputtering, the magnet is placed in a special material box with a high-temperature resistant thin ceramic plate at the bottom. The heat treatment parameters are 900℃ for 25 hours; then cooled to 60℃ in the furnace, and then heated to 450℃ and held at 450℃ for 15 hours.

[0100] 6. The BH curve of the magnet after dysprosium infiltration was directly tested using Metis. The coercivity of the magnet increased by 8000 Oe, while the remanence decreased slightly by 240 Gs. The changes in magnet performance before and after dysprosium infiltration are shown in Table 1.

[0101] Example 5

[0102] A method for preparing large-size rare-earth permanent magnet materials, the specific steps of which are as follows:

[0103] 1. Prepare a basic magnet blank with low (Al+Cu) content, with an (Al+Cu) content of 0.3wt% and a Dy content of 4%, corresponding to an elemental composition ratio of (PrNd). 30.2 Dy 1.3 Cu 0.11 Al 0.12 Fe bal B1 is prepared using a low-oxygen process, with a Br content of 14.08 kGs and a coercivity of 18.38 kGs in the basic magnet blank.

[0104] 2. Machining the basic magnet blank to produce a product with dimensions of 25*21*6mm and a magnet penetration direction of 6mm.

[0105] 3. Immerse the magnet in a degreasing agent for 10 minutes to remove oil stains from its surface. Rinse the surface with clean water, then acid-wash with HNO3 for about 30 seconds, followed by water washing and ultrasonic treatment for 30 seconds, and finally rapid drying with strong airflow.

[0106] 4. Place the magnet in the sputtering furnace and sputter the two orientation surfaces of the magnet. The sputtering voltage is 30V, the vacuum degree is 0.13Pa, and the sputtering time is 50min.

[0107] A composite metal target is used as the sputtering source during sputtering. The preparation process of the composite metal target is as follows:

[0108] According to H 100-x-y M x Q y The chemical formula is used to smelt the target material using a vacuum intermediate frequency induction method, with a vacuum degree of not less than 10 during smelting. -2Pa, the composite metal target has a thickness of 0.5-3mm, a length of 200-300mm, and a width of 100-240mm, where H is Tb; M is any one of Nd, Pr, and NdPr; Q is any one or two of Cu, Al, Zn, and Sn; 0≤x≤20; 0≤y≤20. For example, it can be Tb, Tb 60 Nd 20 Cu 20 、Tb 60 Pr 20 Al 20 、Tb 60 Pr 20 Zn 20 、Tb 50 Pr 25 Sn 25 One of them, where x and y are weight percentages.

[0109] 5. After sputtering, the magnet is placed in a special material box with a high-temperature resistant thin ceramic plate at the bottom. The heat treatment parameters are 900℃ for 25 hours; then cooled to 60℃ in the furnace, and then heated to 450℃ and held at 450℃ for 15 hours.

[0110] 6. The BH curve of the magnet after dysprosium infiltration was directly tested by Metis. The coercivity of the magnet increased by 7890 Oe, while the remanence decreased slightly by 220 Gs. The changes in magnet performance before and after dysprosium infiltration are shown in Table 1.

[0111] Example 6

[0112] A method for preparing large-size rare-earth permanent magnet materials, the specific steps of which are as follows:

[0113] 1. Prepare a basic magnet blank with low (Al+Cu) content, with an (Al+Cu) content of 0.23wt% and a Dy content of 1.3%, corresponding to an elemental composition ratio of (PrNd). 30.2 Dy 1.3 Cu 0.11 Al 0.12 Fe bal B1 is prepared using a low-oxygen process, with a Br content of 14.08 kGs and a coercivity of 18.38 kGs in the basic magnet blank.

[0114] 2. Machining the basic magnet blank to produce a product with dimensions of 32*21*4mm and a magnet penetration direction of 4mm.

[0115] 3. Immerse the magnet in degreasing agent for 10 minutes to remove oil stains from the magnet surface. After rinsing the surface with water, acid-wash with HNO3 for about 30 seconds, then rinse with water and ultrasonically treat for 30 seconds, and finally dry quickly with strong air.

[0116] 4. Place the magnet in the sputtering furnace and sputter the two orientation surfaces of the magnet. The sputtering voltage is 30V, the vacuum degree is 0.13Pa, and the sputtering time is 50min.

[0117] A composite metal target is used as the sputtering source during sputtering. The preparation process of the composite metal target is as follows:

[0118] According to H 100-x-y M x Q y The chemical formula is used to smelt the target material using a vacuum intermediate frequency induction method, with a vacuum degree of not less than 10 during smelting. -2 Pa, the composite metal target has a thickness of 0.5-3mm, a length of 200-300mm, and a width of 100-240mm, where H is Tb; M is any one of Nd, Pr, and NdPr; Q is any one or two of Cu, Al, Zn, and Sn; 0≤x≤20; 0≤y≤20. For example, it can be Tb, Tb 60 Nd 20 Cu 20 、Tb 60 Pr 20 Al 20 、Tb 60 Pr 20 Zn 20 、Tb 50 Pr 25 Sn 25 One of them, where x and y are weight percentages.

[0119] 5. After sputtering, the magnet is placed in a special material box with a high-temperature resistant thin ceramic plate at the bottom. The heat treatment parameters are 900℃ for 25 hours. The magnet is then cooled to 60℃ in the furnace and then heated to 450℃. The magnet is then held at 450℃ for 15 hours.

[0120] 6. The BH curve of the magnet after dysprosium infiltration was directly tested by Metis. The coercivity of the magnet increased by 9990 Oe, while the remanence decreased slightly by 340 Gs. The changes in magnet performance before and after dysprosium infiltration are shown in Table 1.

[0121] Table 1 shows the test results for the six embodiments.

[0122]

[0123]

[0124] As can be seen from Table 1 above, after processing the basic magnet blank using the method of the present invention, the coercivity is improved and the remanence is reduced.

[0125] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing large-size rare-earth permanent magnet materials, characterized in that, The specific steps are as follows: The basic magnet blank is pretreated; the basic magnet blank is prepared using a low-oxygen process, and the sum of the contents of Al and Cu in the basic magnet blank is greater than 0 wt% and less than 0.4 wt%. The pretreated magnet is subjected to sputtering treatment; the sputtering treatment uses a composite metal target as the sputtering source. The composite metal target material is H. 100-x-y M x Q y Where H is Tb; M is any one of Nd, Pr, and NdPr; Q is any one or two of Cu, Al, Zn, and Sn; 0≤x≤20; 0≤y≤20; the sputtered magnet is heat-treated to obtain the desired rare-earth permanent magnet material, including: After sputtering, the magnets are placed in a material box for heat treatment. A high-temperature resistant thin ceramic plate is placed at the bottom of the material box. The heat treatment temperature is divided into two stages: first, treatment at 600-900℃ for 25-35 hours; then, low-temperature tempering at 400-600℃ for 3-15 hours to obtain the desired rare earth permanent magnet material. The dimensions of the large-size rare earth permanent magnet material are: width not less than 20mm and orientation dimension between 2-10mm.

2. The method for preparing a large-size rare-earth permanent magnet material according to claim 1, characterized in that, The specific process for pre-processing the basic magnet blank is as follows: Preparation of basic magnet blanks; The basic magnet blank is machined to obtain a basic magnet of the required size; Clean the base magnet.

3. The method for preparing a large-size rare-earth permanent magnet material according to claim 2, characterized in that, The specific process for cleaning the basic magnet is as follows: the basic magnet to be treated is immersed in degreasing agent to remove the oil stains on the surface of the magnet, then the surface is washed with clean water, then acid washed with HNO3 solution, then ultrasonically washed, and finally dried quickly with strong air.

4. The method for preparing a large-size rare-earth permanent magnet material according to claim 3, characterized in that, The base magnet to be treated is immersed in the degreasing agent for 8-12 minutes, acid-washed with HNO3 solution for 20-40 seconds, and ultrasonically washed with water for 20-40 seconds.

5. The method for preparing a large-size rare-earth permanent magnet material according to claim 1, characterized in that, The specific conditions for the sputtering process are as follows: a composite metal target is used as the sputtering source, sputtering is performed at a voltage of 28-35V for 30-70 minutes, double-sided sputtering is achieved by flipping the target, and the vacuum degree during the sputtering process is 0.13Pa.

6. The method for preparing a large-size rare-earth permanent magnet material according to claim 5, characterized in that, The preparation process of the composite metal target is as follows: According to H 100-x-y M x Q y The chemical formula is used to smelt the target material using a vacuum intermediate frequency induction method, with a vacuum degree of not less than 10 during smelting. -2 Pa, the composite metal target has a thickness of 0.5-3mm, a length of 200-300mm, and a width of 100-240mm, where H is Tb; M is any one of Nd, Pr, and NdPr; Q is any one or two of Cu, Al, Zn, and Sn; 0≤x≤20; 0≤y≤20.

7. A rare earth permanent magnet material prepared by the preparation method of large-size rare earth permanent magnet material as described in any one of claims 1-6.

8. The rare earth permanent magnet material according to claim 7, characterized in that, Compared to the basic magnet blank, the rare earth permanent magnet material has a coercivity that is increased by 6930-9990 Oe and a remanence that is reduced by 220-340 Gs.

9. The rare earth permanent magnet material according to claim 8, characterized in that, The chemical formula of the basic magnet blank is (PrNd). 31.5-m Dy m (Cu+Al) n Fe bal B1, where m and n are the mass percentages of the corresponding elements, and 0 < m ≤ 4, 0 < n ≤ 0.4, the terbium content in the rare earth permanent magnet material is 0.6 wt%.

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