Sintered cerium gadolinium yttrium iron boron permanent magnet, preparation method and application thereof

Abstract

This invention provides a sintered cerium-gadolinium-yttrium iron boron permanent magnet, its preparation method, and its application, belonging to the field of permanent magnet technology. The invention uses waste sintered cerium-yttrium iron boron magnets and a mixture of gadolinium and yttrium as hydrogen-crushing raw materials; the hydrogen-crushing raw materials are subjected to hydrogen crushing to obtain coarse cerium-gadolinium-yttrium iron boron powder; the coarse cerium-gadolinium-yttrium iron boron powder is then subjected to air jet milling to obtain fine cerium-gadolinium-yttrium iron boron powder; the fine cerium-gadolinium-yttrium iron boron powder is mixed with air jet mill bottom material and a lubricant to obtain a mixed fine powder material; the air jet mill bottom material is the bottom material generated during the air jet milling process of the coarse cerium-gadolinium-yttrium iron boron powder or the bottom material generated during the air jet milling process of magnets with a magnetic energy product greater than 45 MGOe; the mixed fine powder material is sequentially subjected to orientation molding, sintering, and tempering treatment to obtain the sintered cerium-gadolinium-yttrium iron boron permanent magnet. The method provided by this invention for preparing sintered cerium gadolinium yttrium iron boron permanent magnets enables comprehensive utilization of rare earth resources and results in low production costs.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet technology, specifically to a sintered cerium gadolinium yttrium iron boron permanent magnet, its preparation method, and its application. Background Technology

[0002] The existing production process for sintered cerium-containing permanent magnets typically includes casting, hydrogen crushing, air jet milling, orientation forming, isostatic pressing, sintering, and tempering. The casting process usually uses praseodymium-neodymium metal and other metals as raw materials to prepare rapidly solidified sheets, which consumes a large amount of expensive praseodymium-neodymium metal. Furthermore, the air jet milling process generates mill runoff, which permanent magnet manufacturers typically choose to discard directly. However, this mill runoff contains some rare earth elements, and discarding it directly results in a waste of these rare earth components.

[0003] Given the challenging market environment, scarce rare earth resources, and tight financial constraints, developing a low-cost method for preparing sintered cerium permanent magnets is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a sintered cerium gadolinium yttrium iron boron permanent magnet, its preparation method, and its application. The sintered cerium gadolinium yttrium iron boron permanent magnet prepared by the method provided by this invention can be applied to electric bicycles or wind power generators, enabling comprehensive utilization of rare earth resources and reducing production costs.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing sintered cerium gadolinium yttrium iron boron permanent magnets, comprising the following steps:

[0007] Provide hydrogen crushing raw materials, wherein the hydrogen crushing raw materials are waste sintered cerium iron boron magnets, a mixture of gadolinium and yttrium;

[0008] The hydrogen-crushed raw material was subjected to hydrogen crushing to obtain cerium-gadolinium-yttrium iron-boron coarse powder;

[0009] The coarse cerium-gadolinium-yttrium iron boron powder was subjected to air jet milling to obtain fine cerium-gadolinium-yttrium iron boron powder;

[0010] The cerium gadolinium yttrium iron boron fine powder is mixed with air jet mill base material and lubricant to obtain mixed fine powder material; the air jet mill base material is the base material generated during the air jet milling process of the cerium gadolinium yttrium iron boron coarse powder or the base material generated during the air jet milling process of a magnet with a magnetic energy product greater than 45 MGOe.

[0011] The mixed fine powder material is sequentially subjected to orientation molding, sintering and tempering treatment to obtain sintered cerium gadolinium yttrium iron boron permanent magnets.

[0012] Preferably, by mass fraction, the composition of the waste sintered cerium-iron-boron magnet includes: M 20.2%–22.2%, Ce 7%–9%, ​​Gd 1%–2%, Dy 0.3%–0.7%, Zr 0.1%–0.2%, Ti 0.1%–0.2%, Cu 0.1%–0.2%, Ga 0.1%–0.3%, B 0.93%–0.96%, with the balance being Fe; wherein M is Pr and Nd;

[0013] The mass ratio of the waste sintered cerium iron boron magnet, gadolinium and yttrium is (85-93):(5-10):(2-5).

[0014] Preferably, the hydrogen crushing includes sequential hydrogen absorption and dehydrogenation treatments; the temperature of the hydrogen absorption treatment is 270℃~300℃, and the holding time is 30min~60min; the temperature of the dehydrogenation treatment is 500℃~620℃, and the holding time is 4h~6h.

[0015] Preferably, the grinding pressure of the air jet mill is 5.9 MPa to 6.1 MPa, and the powder output speed is 270 kg / h to 320 kg / h; the average particle size d50 of the cerium gadolinium yttrium iron boron fine powder is 5.0 μm to 5.5 μm.

[0016] Preferably, the mass of the air jet mill substrate does not exceed 15% of the mass of the cerium gadolinium yttrium iron boron powder, and the mass of the lubricant is 4‰ to 6‰ of the total mass of the cerium gadolinium yttrium iron boron powder and the air jet mill substrate.

[0017] Preferably, the orientation forming is carried out under conditions of magnetic induction intensity ≥1.5T and forming pressure of 3MPa~5MPa; the density of the green body obtained after orientation forming is 4.02g / cm³. 3 ~4.15g / cm 3 .

[0018] Preferably, the sintering temperature is 1020℃~1045℃, the holding time is 2h~4h, and the vacuum degree is <8×10 - 3 Pa.

[0019] Preferably, the tempering process includes a first tempering process and a second tempering process performed sequentially; the conditions for the first tempering process include: vacuum degree < 8 × 10⁻⁶. -3 The conditions for the second tempering treatment include: vacuum degree <5Pa, temperature of 400℃~480℃, and holding time of 4h~6h.

[0020] This invention provides a sintered cerium gadolinium yttrium iron boron permanent magnet prepared by the preparation method described in the above technical solution.

[0021] This invention provides the application of the sintered cerium gadolinium yttrium iron boron permanent magnet described above in electric bicycles or wind power generators.

[0022] This invention provides a method for preparing sintered cerium-gadolinium-yttrium iron boron permanent magnets, comprising the following steps: providing hydrogen-crushed raw materials, wherein the hydrogen-crushed raw materials are a mixture of waste sintered cerium-yttrium magnets, gadolinium, and yttrium; hydrogen-crushing the hydrogen-crushed raw materials to obtain coarse cerium-gadolinium-yttrium iron boron powder; subjecting the coarse cerium-gadolinium-yttrium iron boron powder to air jet milling to obtain fine cerium-gadolinium-yttrium iron boron powder; mixing the fine cerium-gadolinium-yttrium iron boron powder with air jet mill bottom material and lubricant to obtain mixed fine powder material; wherein the air jet mill bottom material is the bottom material generated during the air jet milling process of the coarse cerium-gadolinium-yttrium iron boron powder or the bottom material generated during the air jet milling process of magnets with a magnetic energy product greater than 45 MGOe; and sequentially subjecting the mixed fine powder material to orientation molding, sintering, and tempering treatment to obtain sintered cerium-gadolinium-yttrium iron boron permanent magnets. This invention uses waste sintered cerium-iron-boron magnets as the base material, adds gadolinium and yttrium for hydrogen crushing, and adds air jet mill bottom material containing rare earth elements after air jet milling. This can repair the rare earth-rich phase in the oxidized waste sintered cerium-iron-boron magnets, recycle the waste air jet mill bottom material, promote the balanced utilization of light and heavy rare earth resources, and reduce the amount of rare earth praseodymium and neodymium used, saving production costs. At the same time, by combining the hydrogen crushing process, air jet milling process, and sintering process to optimize and control the rare earth-rich phase, it is possible to finally prepare sintered cerium-gadolinium-yttrium iron-boron permanent magnets with magnetic properties of 13 kGs remanence and 17.5 kOe coercivity. The product has good stability and can meet the needs of the electric bicycle or wind power generator market. Detailed Implementation

[0023] This invention provides a method for preparing sintered cerium gadolinium yttrium iron boron permanent magnets, comprising the following steps:

[0024] Provide hydrogen crushing raw materials, wherein the hydrogen crushing raw materials are waste sintered cerium iron boron magnets, a mixture of gadolinium and yttrium;

[0025] The hydrogen-crushed raw material was subjected to hydrogen crushing to obtain cerium-gadolinium-yttrium iron-boron coarse powder;

[0026] The coarse cerium-gadolinium-yttrium iron boron powder was subjected to air jet milling to obtain fine cerium-gadolinium-yttrium iron boron powder;

[0027] The cerium gadolinium yttrium iron boron fine powder is mixed with air jet mill base material and lubricant to obtain mixed fine powder material; the air jet mill base material is the base material generated during the air jet milling process of the cerium gadolinium yttrium iron boron coarse powder or the base material generated during the air jet milling process of a magnet with a magnetic energy product greater than 45 MGOe.

[0028] The mixed fine powder material is sequentially subjected to orientation molding, sintering and tempering treatment to obtain sintered cerium gadolinium yttrium iron boron permanent magnets.

[0029] The method provided by this invention improves the rare-earth-rich phase in waste sintered cerium-gadolinium-yttrium magnets by introducing gadolinium, yttrium, and air-jet milling substrate containing rare earth elements. By optimizing and controlling the rare-earth-rich phase through hydrogen crushing, air-jet milling, and sintering processes, the method enables comprehensive utilization of rare earth resources. This allows for the low-cost preparation of sintered cerium-gadolinium-yttrium permanent magnets with 13 kGs remanence and 17.5 kOe coercivity, enhancing product competitiveness and suitability for mass production, thus meeting the needs of the electric bicycle and wind power generator markets. The preparation method of the sintered cerium-gadolinium-yttrium permanent magnets provided by this invention is described below.

[0030] This invention provides hydrogen-based crushing raw materials, which are mixtures of waste sintered cerium-iron-boron magnets, gadolinium, and yttrium. In this invention, the composition of the waste sintered cerium-iron-boron magnets, by mass fraction, preferably includes: M2 0.2%–22.2%, Ce 7%–9%, ​​Gd 1%–2%, Dy 0.3%–0.7%, Zr 0.1%–0.2%, Ti 0.1%–0.2%, Cu 0.1%–0.2%, Ga 0.1%–0.3%, B 0.93%–0.96%; specifically, it can be M2 1.2%, Ce 8%, Gd 1%, Dy 0.5%, Zr 0.2%, Ti 0.2%, Cu 0.2%, Ga 0.2%, B 0.95%, with the balance being Fe; or it can be M2 2. 2%, Ce 7%, Gd 1.3%, Dy 0.3%, Zr 0.15%, Ti 0.2%, Cu 0.2%, Ga 0.2%, B 0.95%, balance Fe; or M2 0.2%, Ce 9%, Gd 1%, Dy 0.7%, Zr 0.15%, Ti 0.15%, Cu 0.2%, Ga 0.2%, B 0.95%, balance Fe; or M2 1.4%, Ce 8.5%, Gd 1.2%, Dy 0.6%, Zr 0.18%, Ti 0.18%, Cu 0.2%, Ga 0.2%, B 0.95%, balance Fe. In this invention, M represents Pr and Nd, and the preferred mass ratio of Pr to Nd is (4.4–5.1):(15.1–17.8), more preferably 4.6:16.6, 4.8:16.2, 5.1:17.1, 5.1:15.1, or 5.0:16.4. In an embodiment of this invention, waste sintered cerium-iron-boron magnets of grade 42H are specifically used. In this invention, gadolinium is specifically metallic gadolinium, and yttrium is specifically metallic yttrium. In this invention, the preferred mass ratio of the waste sintered cerium-iron-boron magnets, gadolinium, and yttrium is (85–93):(5–10):(2–5), more preferably 90:5:5 or 89:6:5. This invention preferably limits the mass ratio of the waste sintered cerium-iron-boron magnets, gadolinium, and yttrium to the above ranges, which fully utilizes the properties of each element while also considering process operability.

[0031] After obtaining the hydrogen-crushed raw material, the present invention further hydrogen-crushes the raw material to obtain cerium-gadolinium-yttrium iron boron coarse powder. In the present invention, the hydrogen crushing preferably includes sequential hydrogen absorption and dehydrogenation treatments; the temperature of the hydrogen absorption treatment is preferably 270℃~300℃, more preferably 280℃~290℃, and the holding time is preferably 30min~60min, more preferably 40min~50min; the temperature of the dehydrogenation treatment is preferably 500℃~620℃, more preferably 520℃~550℃, further preferably 530℃~540℃, and the holding time is preferably 4~6h, more preferably 4.5h~5h. After the dehydrogenation treatment, the present invention preferably cools to room temperature to obtain cerium-gadolinium-yttrium iron boron coarse powder. The present invention does not have a specific limitation on the particle size of the cerium-gadolinium-yttrium iron boron coarse powder.

[0032] After obtaining coarse cerium-gadolinium-yttrium iron boron powder, the present invention further processes the coarse cerium-gadolinium-yttrium iron boron powder into fine cerium-gadolinium-yttrium iron boron powder by air jet milling. In the present invention, the grinding pressure of the air jet milling is preferably 5.9 MPa to 6.1 MPa, more preferably 6 MPa; the powder output speed is preferably 270 kg / h to 320 kg / h, more preferably 285 kg / h to 300 kg / h; the average particle size d50 of the fine cerium-gadolinium-yttrium iron boron powder is preferably 5.0 μm to 5.5 μm, more preferably 5.2 μm to 5.3 μm. In the present invention, no antioxidant is required when processing the coarse cerium-gadolinium-yttrium iron boron powder by air jet milling. In the process of preparing sintered cerium-containing permanent magnets, an air jet milling process is usually included. This process generates air jet mill bottom material, which contains rare earth components. Permanent magnet manufacturers usually choose to discard this bottom material directly. This invention utilizes the bottom material generated during the air jet milling process of cerium-gadolinium-yttrium iron boron coarse powder, or the bottom material generated during the air jet milling process of magnets with a magnetic energy product greater than 45 MGOe, to prepare sintered cerium-gadolinium-yttrium iron boron permanent magnets. This allows for the comprehensive utilization of rare earth resources and reduces the production cost of sintered cerium-gadolinium-yttrium iron boron permanent magnets.

[0033] After obtaining the cerium-gadolinium-yttrium iron boron (CGAY-FeB) fine powder, this invention mixes the CGAY-FeB fine powder with air jet mill base material and a lubricant to obtain a mixed fine powder material. The air jet mill base material is either the base material generated during the air jet milling process of the CGAY-FeB coarse powder or the base material generated during the air jet milling process of a magnet with a magnetic energy product greater than 45 MGOe. Specifically, the air jet mill base material can be the base material generated during the air jet milling process of the CGAY-FeB coarse powder, or it can be the base material generated during the air jet milling process of a magnet with a magnetic energy product greater than 45 MGOe. This invention does not specifically limit the magnet with a magnetic energy product greater than 45 MGOe; any base material generated during the air jet milling process of a magnet with a magnetic energy product greater than 45 MGOe, as well as those well known to those skilled in the art, is acceptable. In an embodiment of the present invention, the base material produced during the air jet milling process in the production of a magnet with a magnetic energy product of 45.7 MGOe is used as the base material for air jet milling to prepare the sintered cerium-gadolinium-yttrium iron-boron permanent magnet described in this application. Specifically, the nominal composition of the magnet with a magnetic energy product of 45.7 MGOe, by mass percentage, is as follows: praseodymium-neodymium content is 29.7% (wherein, the mass ratio of Pr to Nd is 7.2:22.5), Dy content is 0.7%, Zr content is 0.10%, Cu content is 0.2%, Ga content is 0.2%, B content is 0.91%, Al content is 0.25%, and the balance is Fe. In this invention, the mass of the air jet mill substrate preferably does not exceed 15% of the mass of the cerium gadolinium yttrium iron boron powder, and the mass of the air jet mill substrate is preferably 10-14% of the mass of the cerium gadolinium yttrium iron boron powder, more preferably 11-12%; the mass of the lubricant is preferably 4‰-6‰ of the total mass of the cerium gadolinium yttrium iron boron powder and the air jet mill substrate, more preferably 5‰; the lubricant is preferably a grease lubricant. In this invention, the mixing is preferably stirring, and the stirring time is preferably 1.5h-2.5h, more preferably 2h.

[0034] After obtaining the mixed fine powder material, the present invention sequentially performs orientation molding, sintering, and tempering treatment on the mixed fine powder material to obtain sintered cerium gadolinium yttrium iron boron permanent magnets. In the present invention, the orientation molding is preferably carried out under the conditions of magnetic induction intensity ≥1.5T and molding pressure of 3MPa~5MPa, the magnetic induction intensity is further preferably 1.6T~1.72T, even more preferably 1.65T~1.68T, the molding pressure is further preferably 3.5MPa~4.5MPa, even more preferably 4MPa~4.3MPa; the density of the green body obtained after orientation molding is preferably 4.02g / cm³. 3 ~4.15g / cm 3 Further 4.05 g / cm 3 ~4.12g / cm 3 A further preferred value is 4.07 g / cm³.3 ~4.10g / cm 3 In an embodiment of the present invention, the orientation forming is specifically performed in a magnetic field press. In this invention, after the orientation forming, there is no need for an isostatic pressing process; the sintered cerium-gadolinium-yttrium iron-boron permanent magnet can be directly prepared through subsequent sintering and tempering treatments. This significantly shortens the preparation cycle of the permanent magnet and helps to further reduce costs.

[0035] After the orientation forming, the resulting green body is sintered to obtain sintered material. In this invention, the sintering temperature is preferably 1020℃~1045℃, more preferably 1025℃~1043℃, and even more preferably 1030℃~1040℃; the holding time is preferably 2h~4h, more preferably 2.5h~3h. Preferably, the temperature is raised from room temperature to the required sintering temperature at a first heating rate, preferably 2℃ / min~4℃ / min, more preferably 2.5℃ / min~3℃ / min; in an embodiment of this invention, the room temperature is specifically 25℃. In an embodiment of this invention, the sintering is specifically carried out in a sintering furnace. After sintering, the temperature is preferably lowered to 40℃~60℃ at a first cooling rate to obtain sintered material; the first cooling rate is preferably 7℃ / min~9℃ / min, more preferably 8℃ / min~8.3℃ / min.

[0036] After obtaining the sintered material, the present invention performs a tempering treatment on the sintered material to obtain a sintered cerium-gadolinium-yttrium iron-boron permanent magnet. In the present invention, the tempering treatment preferably includes a first tempering treatment and a second tempering treatment performed sequentially; the conditions for the first tempering treatment include: a vacuum degree preferably <8×10⁻⁶. -3 Pa, more preferably 6 × 10 Pa -3Pa; the preferred temperature is 580℃~650℃, more preferably 600℃~630℃; the preferred holding time is 2h~3h, more preferably 2h; the conditions for the second tempering treatment include: the vacuum degree is preferably <5Pa, more preferably 3Pa; the preferred temperature is 400℃~480℃, more preferably 445℃~460℃; the preferred holding time is 4h~6h, more preferably 5h. In this invention, the temperature is preferably raised to the temperature required for the first tempering treatment at a second heating rate, and then subjected to the first tempering treatment; after the first tempering treatment, the temperature is lowered to 40℃~60℃ at a second cooling rate, and then raised to the temperature required for the second tempering treatment at a third heating rate, and then subjected to the second tempering treatment; after the second tempering treatment, the temperature is lowered to 30℃~40℃ at a third cooling rate to obtain a sintered cerium-gadolinium-yttrium iron-boron permanent magnet. In this invention, the second heating rate is preferably 5℃ / min to 7℃ / min, more preferably 6℃ / min; the second cooling rate is preferably 10℃ / min to 12℃ / min, more preferably 10.5℃ / min; the third heating rate is preferably 4℃ / min to 6℃ / min, more preferably 5.5℃ / min; and the third cooling rate is preferably 11℃ / min to 13℃ / min, more preferably 12℃ / min. In this invention, the cooling method after the first tempering treatment and the second tempering treatment is preferably continuous air cooling with nitrogen.

[0037] This invention provides a sintered cerium gadolinium yttrium iron boron permanent magnet prepared by the preparation method described in the above technical solution.

[0038] This invention provides the application of the sintered cerium gadolinium yttrium iron boron permanent magnet described above in electric bicycles or wind power generators.

[0039] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Example 1

[0041] In this embodiment, waste sintered cerium-iron-boron magnets of grade 42H were used. The composition of the magnets was tested and found to be as follows by mass percentage: praseodymium-neodymium content 21.2% (of which, the mass ratio of Pr to Nd is 4.8:16.2), Ce content 8%, Gd content 1%, Dy content 0.5%, Zr content 0.2%, Ti content 0.2%, Cu content 0.2%, Ga content 0.2%, B content 0.95%, and the balance being Fe.

[0042] The waste sintered cerium iron boron magnets were mixed with gadolinium and yttrium in a mass ratio of 90:5:5 and then subjected to hydrogen crushing. Specifically, hydrogen absorption was carried out at 300°C for 50 minutes, followed by dehydrogenation at 520°C for 4.5 hours. After cooling to room temperature (25°C), cerium gadolinium yttrium iron boron coarse powder was obtained.

[0043] The coarse cerium gadolinium yttrium iron boron powder is subjected to air jet milling. The grinding pressure during the air jet milling process is 6 MPa, and no antioxidant is added. The powder output speed is 300 kg / h, resulting in fine cerium gadolinium yttrium iron boron powder with an average particle size d50 of 5.3 μm. At the same time, air jet mill bottom material is also obtained.

[0044] The cerium gadolinium yttrium iron boron fine powder, the air jet mill base material, and the grease lubricant are stirred and mixed for 2 hours to obtain a mixed fine powder material; wherein, the mass of the air jet mill base material is 12% of the mass of the cerium gadolinium yttrium iron boron fine powder, and the mass of the grease lubricant is 5‰ of the total mass of the cerium gadolinium yttrium iron boron fine powder and the air jet mill base material.

[0045] The mixed fine powder material was placed in a magnetic field press and oriented under conditions of magnetic induction intensity of 1.65T and molding pressure of 4.3MPa to obtain a density of 4.1g / cm³. 3 raw blanks;

[0046] The green blank was placed in a sintering furnace and heated from room temperature to 1040°C at a rate of 2.8°C / min, and sintered for 3 hours to obtain the sintered material. Then, the temperature was lowered to 45°C at a rate of 8°C / min, and then raised to 630°C at a rate of 6°C / min, while controlling the vacuum degree to 6 × 10⁻⁶. -3 The first tempering treatment was carried out at 3 Pa for 2 hours, followed by continuous air cooling with nitrogen (cooling rate of 10.5℃ / min) to 50℃, then heated to 460℃ at a rate of 5.5℃ / min, and the vacuum degree was controlled at 3 Pa. The second tempering treatment was carried out at 3 Pa for 5 hours, and finally cooled to 35℃ with continuous air cooling with nitrogen (cooling rate of 12℃ / min) to obtain sintered cerium gadolinium yttrium iron boron permanent magnets.

[0047] Three sintered cerium-gadolinium-yttrium iron-boron permanent magnet samples were prepared repeatedly according to the method in Example 1, and then subjected to 20°C. The cylindrical test specifically measured the remanence (Br), coercivity (Hcb), intrinsic coercivity (Hcj), magnetic energy product ((BH)max), reverse magnetic field (Hk) at J=0.9Jr on the J-demagnetization curve of the magnet, and squareness (Hk / Hcj). The specific results are shown in Table 1. Table 1 shows that the sintered cerium-gadolinium-yttrium iron-boron permanent magnets prepared using the method provided by this invention achieve a remanence of 13 kGs and an intrinsic coercivity of 17.5 kOe. Furthermore, Table 1 shows that the sintered cerium-gadolinium-yttrium iron-boron permanent magnets prepared using the method provided by this invention exhibit good product stability.

[0048] Table 1. Performance test results of three sintered cerium gadolinium yttrium iron boron permanent magnet samples in Example 1.

[0049]

[0050] Example 2

[0051] In this embodiment, waste sintered cerium-iron-boron magnets of grade 42H were used. The composition of the magnets was tested and found to be as follows by mass percentage: praseodymium-neodymium content 22.2% (of which, the mass ratio of Pr to Nd is 5.1:17.1), Ce content 7%, Gd content 1.3%, Dy content 0.3%, Zr content 0.15%, Ti content 0.2%, Cu content 0.2%, Ga content 0.2%, B content 0.95%, and the balance being Fe.

[0052] The waste sintered cerium iron boron magnets were mixed with gadolinium and yttrium in a mass ratio of 90:5:5 and then subjected to hydrogen crushing. Specifically, hydrogen absorption was carried out at 290°C for 50 minutes, followed by dehydrogenation at 540°C for 4 hours, and then cooled to room temperature (25°C) to obtain cerium gadolinium yttrium iron boron coarse powder.

[0053] The coarse cerium gadolinium yttrium iron boron powder is subjected to air jet milling. The grinding pressure during the air jet milling process is 6 MPa, and no antioxidant is added. The powder output speed is 285 kg / h, resulting in fine cerium gadolinium yttrium iron boron powder with an average particle size d50 of 5.0 μm. At the same time, air jet mill bottom material is also obtained.

[0054] The cerium gadolinium yttrium iron boron fine powder, the air jet mill base material, and the grease lubricant are stirred and mixed for 2 hours to obtain a mixed fine powder material; wherein, the mass of the air jet mill base material is 12% of the mass of the cerium gadolinium yttrium iron boron fine powder, and the mass of the grease lubricant is 5‰ of the total mass of the cerium gadolinium yttrium iron boron fine powder and the air jet mill base material.

[0055] The mixed fine powder material was placed in a magnetic field press and oriented under conditions of magnetic induction intensity of 1.6T and molding pressure of 4MPa to obtain a density of 4.07 g / cm³. 3 raw blanks;

[0056] The green blank was placed in a sintering furnace and heated from room temperature to 1045°C at a rate of 2.8°C / min, and sintered for 3 hours to obtain the sintered material. Then, the temperature was lowered to 45°C at a rate of 8°C / min, and then raised to 630°C at a rate of 6°C / min, while controlling the vacuum degree to 6 × 10⁻⁶. -3 The first tempering treatment was carried out at 3 Pa for 2 hours, followed by continuous air cooling with nitrogen (cooling rate of 10.5℃ / min) to 50℃, then heated to 460℃ at a rate of 5.5℃ / min, and the vacuum degree was controlled at 3 Pa. The second tempering treatment was carried out at 3 Pa for 5 hours, and finally cooled to 35℃ with continuous air cooling with nitrogen (cooling rate of 12℃ / min) to obtain sintered cerium gadolinium yttrium iron boron permanent magnets.

[0057] Three sintered cerium-gadolinium-yttrium iron-boron permanent magnet samples were prepared repeatedly according to the method in Example 2, and then subjected to 20°C. The cylindrical test specifically measured the remanence (Br), coercivity (Hcb), intrinsic coercivity (Hcj), magnetic energy product ((BH)max), reverse magnetic field (Hk) at J=0.9Jr on the J-demagnetization curve of the magnet, and squareness (Hk / Hcj). The specific results are shown in Table 2. Table 2 shows that the sintered cerium-gadolinium-yttrium iron-boron permanent magnets prepared using the method provided by this invention achieve a remanence of 13 kGs and an intrinsic coercivity of 17.5 kOe. Furthermore, Table 2 shows that the sintered cerium-gadolinium-yttrium iron-boron permanent magnets prepared using the method provided by this invention exhibit good product stability.

[0058] Table 2 shows the performance test results of the three sintered cerium gadolinium yttrium iron boron permanent magnet samples in Example 2.

[0059]

[0060]

[0061] Example 3

[0062] In this embodiment, waste sintered cerium-iron-boron magnets of grade 42H were used. The composition of the magnets was tested and found to be as follows by mass percentage: praseodymium-neodymium content 20.2% (of which, the mass ratio of Pr to Nd is 5.1:15.1), Ce content 9%, Gd content 1%, Dy content 0.7%, Zr content 0.15%, Ti content 0.15%, Cu content 0.2%, Ga content 0.2%, B content 0.95%, and the balance being Fe.

[0063] The waste sintered cerium iron boron magnets were mixed with gadolinium and yttrium in a mass ratio of 89:6:5 and then subjected to hydrogen crushing. Specifically, hydrogen absorption was carried out at 300°C for 50 minutes, followed by dehydrogenation at 550°C for 5 hours, and then cooled to room temperature (25°C) to obtain cerium gadolinium yttrium iron boron coarse powder.

[0064] The coarse cerium gadolinium yttrium iron boron powder is subjected to air jet milling. The grinding pressure during the air jet milling process is 6 MPa, and no antioxidant is added. The powder output speed is 270 kg / h, resulting in fine cerium gadolinium yttrium iron boron powder with an average particle size d50 of 5.0 μm. At the same time, air jet mill bottom material is also obtained.

[0065] The cerium gadolinium yttrium iron boron fine powder, the air jet mill base material, and the grease lubricant are stirred and mixed for 2 hours to obtain a mixed fine powder material; wherein, the mass of the air jet mill base material is 10% of the mass of the cerium gadolinium yttrium iron boron fine powder, and the mass of the grease lubricant is 5‰ of the total mass of the cerium gadolinium yttrium iron boron fine powder and the air jet mill base material.

[0066] The mixed fine powder material was placed in a magnetic field press and oriented under conditions of magnetic induction intensity of 1.72T and molding pressure of 4.5MPa to obtain a density of 4.02g / cm³. 3 raw blanks;

[0067] The green blank was placed in a sintering furnace and heated from room temperature to 1030°C at a rate of 2.8°C / min, and sintered for 3 hours to obtain the sintered material. Then, the temperature was lowered to 45°C at a rate of 8°C / min, and then raised to 600°C at a rate of 6°C / min, while controlling the vacuum degree to 6 × 10⁻⁶. -3 The first tempering treatment was carried out at 3 Pa for 2 hours, followed by continuous air cooling with nitrogen (cooling rate of 10.5℃ / min) to 50℃, then heated to 445℃ at a rate of 5.5℃ / min, and the vacuum degree was controlled at 3 Pa. The second tempering treatment was carried out at 3 Pa for 5 hours, and finally cooled to 35℃ with continuous air cooling with nitrogen (cooling rate of 12℃ / min) to obtain sintered cerium gadolinium yttrium iron boron permanent magnets.

[0068] Three sintered cerium-gadolinium-yttrium iron-boron permanent magnet samples were prepared repeatedly according to the method in Example 3, and then subjected to 20°C. The cylindrical test specifically measured the remanence (Br), coercivity (Hcb), intrinsic coercivity (Hcj), magnetic energy product ((BH)max), reverse magnetic field (Hk) at J=0.9Jr on the J-demagnetization curve of the magnet, and squareness (Hk / Hcj). The specific results are shown in Table 3. Table 3 shows that the sintered cerium-gadolinium-yttrium iron-boron permanent magnets prepared using the method provided by this invention achieve a remanence of 13 kGs and an intrinsic coercivity of 17.5 kOe. Furthermore, Table 3 shows that the sintered cerium-gadolinium-yttrium iron-boron permanent magnets prepared using the method provided by this invention exhibit good product stability.

[0069] Table 3 shows the performance test results of the three sintered cerium gadolinium yttrium iron boron permanent magnet samples in Example 3.

[0070]

[0071] Example 4

[0072] In this embodiment, waste sintered cerium-iron-boron magnets of grade 42H were used. The composition of the magnets, by mass percentage, was as follows: praseodymium-neodymium content 21.4% (of which, the mass ratio of Pr to Nd is 5.0:16.4), Ce content 8.5%, Gd content 1.2%, Dy content 0.6%, Zr content 0.18%, Ti content 0.18%, Cu content 0.2%, Ga content 0.2%, B content 0.95%, and the balance being Fe.

[0073] The waste sintered cerium iron boron magnets were mixed with gadolinium and yttrium in a mass ratio of 90:5:5 and then subjected to hydrogen crushing. Specifically, hydrogen absorption was carried out at 300°C for 50 minutes, followed by dehydrogenation at 520°C for 4.5 hours. After cooling to room temperature (25°C), cerium gadolinium yttrium iron boron coarse powder was obtained.

[0074] The coarse cerium gadolinium yttrium iron boron powder is subjected to air jet milling. The grinding pressure during the air jet milling process is 6 MPa, and no antioxidant is added. The powder output speed is 300 kg / h, resulting in fine cerium gadolinium yttrium iron boron powder with an average particle size d50 of 5.3 μm. At the same time, air jet mill bottom material is also obtained.

[0075] The cerium-gadolinium-yttrium iron boron fine powder, air jet mill base material, and grease lubricant were stirred and mixed for 2 hours to obtain a mixed fine powder material. The air jet mill base material was the base material produced during the air jet milling process in the production of a magnet with a magnetic energy product of 45.7 MGOe. The nominal composition of the magnet, by mass percentage, was: praseodymium-neodymium content 29.7% (wherein the mass ratio of Pr to Nd is 7.2:22.5), Dy content 0.7%, Zr content 0.10%, Cu content 0.2%, Ga content 0.2%, B content 0.91%, Al content 0.25%, with the balance being Fe. The amount of air jet mill base material added was 14% of the mass of the cerium-gadolinium-yttrium iron boron fine powder, and the mass of the grease lubricant was 5‰ of the total mass of the cerium-gadolinium-yttrium iron boron fine powder and the air jet mill base material.

[0076] The mixed fine powder material was placed in a magnetic field press and oriented under conditions of magnetic induction intensity of 1.68T and molding pressure of 4.3MPa to obtain a density of 4.1g / cm³. 3 raw blanks;

[0077] The green blank was placed in a sintering furnace and heated from room temperature to 1043°C at a rate of 2.8°C / min, and sintered for 3 hours to obtain the sintered material. Then, the temperature was lowered to 45°C at a rate of 8°C / min, and then raised to 630°C at a rate of 6°C / min, while controlling the vacuum degree to 6 × 10⁻⁶. -3 The first tempering treatment was carried out at 3 Pa for 2 hours, followed by continuous air cooling with nitrogen (cooling rate of 10.5℃ / min) to 50℃, then heated to 460℃ at a rate of 5.5℃ / min, and the vacuum degree was controlled at 3 Pa. The second tempering treatment was carried out at 3 Pa for 5 hours, and finally cooled to 35℃ with continuous air cooling with nitrogen (cooling rate of 12℃ / min) to obtain sintered cerium gadolinium yttrium iron boron permanent magnets.

[0078] Three sintered cerium-gadolinium-yttrium iron-boron permanent magnet samples were prepared repeatedly according to the method in Example 4, and then subjected to 20°C. The cylindrical test specifically measured the remanence (Br), coercivity (Hcb), intrinsic coercivity (Hcj), magnetic energy product ((BH)max), reverse magnetic field (Hk) at J=0.9Jr on the J-demagnetization curve of the magnet, and squareness (Hk / Hcj). The specific results are shown in Table 4. Table 4 shows that the sintered cerium-gadolinium-yttrium iron-boron permanent magnets prepared using the method provided by this invention achieve a remanence of 13 kGs and an intrinsic coercivity of 17.5 kOe. Furthermore, Table 4 shows that the sintered cerium-gadolinium-yttrium iron-boron permanent magnets prepared using the method provided by this invention exhibit good product stability.

[0079] Table 4 shows the performance test results of the three sintered cerium gadolinium yttrium iron boron permanent magnet samples in Example 4.

[0080]

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a sintered cerium gadolinium yttrium iron boron permanent magnet, comprising the following steps: The raw material for hydrogen crushing is a mixture of waste sintered cerium-iron-boron magnets, gadolinium, and yttrium. By mass fraction, the waste sintered cerium-iron-boron magnets comprise: M 20.2%~22.2%, Ce 7%~9%, Gd 1%~2%, Dy 0.3%~0.7%, Zr 0.1%~0.2%, Ti 0.1%~0.2%, Cu 0.1%~0.2%, Ga 0.1%~0.3%, B 0.93%~0.96%, with the balance being Fe; M is Pr and Nd; the mass ratio of the waste sintered cerium-iron-boron magnets, gadolinium, and yttrium is (85~93):(5~10):(2~5). The hydrogen-crushed raw material was subjected to hydrogen crushing to obtain cerium-gadolinium-yttrium iron-boron coarse powder; The coarse cerium-gadolinium-yttrium iron boron powder is subjected to air jet milling to obtain fine cerium-gadolinium-yttrium iron boron powder; no antioxidant is added during the air jet milling process; the average particle size d50 of the fine cerium-gadolinium-yttrium iron boron powder is 5.0 μm to 5.5 μm; The cerium-gadolinium-yttrium iron boron fine powder is mixed with air jet mill substrate and lubricant to obtain a mixed fine powder material; the air jet mill substrate is the substrate generated during the air jet milling process of the cerium-gadolinium-yttrium iron boron coarse powder or the substrate generated during the air jet milling process of a magnet with a magnetic energy product greater than 45 MGOe; the mass of the air jet mill substrate does not exceed 15% of the mass of the cerium-gadolinium-yttrium iron boron fine powder. The mixed fine powder material is sequentially subjected to orientation molding, sintering and tempering treatment to obtain sintered cerium gadolinium yttrium iron boron permanent magnets.

2. The preparation method according to claim 1, characterized in that, The hydrogen decomposition process includes sequential hydrogen absorption and dehydrogenation treatments; the temperature of the hydrogen absorption treatment is 270℃~300℃, and the holding time is 30min~60min; the temperature of the dehydrogenation treatment is 500℃~620℃, and the holding time is 4h~6h.

3. The preparation method according to claim 1, characterized in that, The grinding pressure of the air jet mill is 5.9 MPa to 6.1 MPa, and the powder output speed is 270 kg / h to 320 kg / h.

4. The preparation method according to claim 1 or 3, characterized in that, The mass of the lubricant is 4‰ to 6‰ of the total mass of the cerium gadolinium yttrium iron boron fine powder and the air jet mill substrate.

5. The preparation method according to claim 1, characterized in that, The orientation forming is carried out under conditions of magnetic induction intensity ≥1.5T and forming pressure of 3MPa~5MPa; the density of the green body obtained after orientation forming is 4.02g / cm³. 3 ~4.15g / cm 3 .

6. The preparation method according to claim 1, characterized in that, The sintering temperature is 1020℃~1045℃, the holding time is 2h~4h, and the vacuum degree is <8×10. -3 Pa.

7. The preparation method according to claim 1 or 6, characterized in that, The tempering process includes a first tempering process and a second tempering process performed sequentially; the conditions for the first tempering process include: vacuum degree <8×10 -3 The conditions for the second tempering treatment are: vacuum degree <5Pa, temperature 580℃~650℃, holding time 2h~4h; and vacuum degree <5Pa, temperature 400℃~480℃, holding time 4h~6h.

8. The sintered cerium gadolinium yttrium iron boron permanent magnet prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the sintered cerium gadolinium yttrium iron boron permanent magnet of claim 8 in electric bicycles or wind power generators.

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