High-temperature-resistant cerium-iron-boron magnet, preparation method thereof and application thereof

Abstract

The application relates to the technical field of magnetic materials, and provides a high-temperature-resistant cerium-iron-boron magnet, a preparation method thereof and application thereof; the high-temperature-resistant cerium-iron-boron magnet is shown in the formula (RE, Ce) x Fe bal M y B z , wherein RE is selected from one or both of Gd and Ho and one or more of Pr, Nd, Dy, La, Tb and Y; M is selected from one or more of Al, Co, Cu, Ga, Ti and Zr; x, y and z are mass percentages of corresponding elements, and 29%<=x<=33%, 0.1%<=y<=2%, 0.89%<=z<=1%, and the mass percentage of Ce is greater than that of RE. The application provides a high-temperature-resistant cerium-iron-boron magnet, the high-temperature-resistant performance of the cerium-iron-boron magnet is improved by introducing Gd and Ho, meanwhile, the content of each element in the cerium-iron-boron magnet is regulated, so that the magnetic performance of the cerium-iron-boron magnet meets the use requirement.

Description

Technical Field

[0001] This invention relates to the field of magnetic materials technology, and in particular to a high-temperature-resistant cerium iron boron magnet, its preparation method, and its applications. Background Technology

[0002] Neodymium iron boron (NdFeB) permanent magnets are widely used in high-tech fields such as new energy vehicles, wind power generation, low-altitude aircraft, and humanoid robots due to their excellent magnetic properties. In recent years, with the continuous expansion of the new energy vehicle and humanoid robot markets, the demand for rare-earth permanent magnet motors has also increased significantly. Nd and Pr, the rare-earth elements that constitute the largest proportion of NdFeB rare-earth permanent magnet motors, have extremely low abundance in the Earth's crust, and their scarcity has become a bottleneck for the further development of NdFeB magnets.

[0003] The rare earth element Ce is far more abundant in nature than Nd and Pr. Replacing NdFeB with Cerium Iron Boron (CFeB) can not only effectively reduce the raw material cost of magnets, but also promote the comprehensive and balanced utilization of rare earth resources. However, Ce's 4f electron layer structure results in a low magnetocrystalline anisotropy field in the alloy materials it forms, and CFeB generally has low magnetic properties, which cannot meet the magnetic performance requirements of practical applications. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a high-temperature-resistant cerium iron boron magnet. The cerium iron boron magnet provided in this application has high temperature resistance while ensuring magnetic properties.

[0005] In view of this, this application provides a high-temperature resistant cerium iron boron magnet as shown in formula (I).

[0006] (RE, Ce) x Fe bal M y B z (I);

[0007] RE is selected from one or two of Gd and Ho and one or more of Pr, Nd, Dy, La, Tb and Y;

[0008] M is selected from one or more of Al, Co, Cu, Ga, Ti, and Zr;

[0009] x, y, and z are the mass percentages of the corresponding elements, with 29%≤x≤33%, 0.1%≤y≤2%, and 0.89%≤z≤1%. The mass percentage of Ce is greater than the mass percentage of RE.

[0010] In some specific embodiments, the RE is selected from Gd, Ho, Pr and Nd.

[0011] In some specific embodiments, the content of Gd is 2-6 wt%, and the content of Ho is 1-2 wt%.

[0012] In some specific embodiments, the Ce content is 15-18 wt%, and / or the total Pr and Nd content is 4-13 wt%.

[0013] In some specific embodiments, M is selected from Al, Co, Cu, and Ga.

[0014] In some specific embodiments, y is 0.5% to 1.5%, and / or z is 0.90% to 0.96%.

[0015] This application also provides a method for preparing the high-temperature-resistant cerium iron boron magnet, comprising the following steps:

[0016] S1. The high-temperature resistant cerium iron boron magnet is prepared according to the above-described composition ratio, and the mixture is mixed to obtain a mixed raw material. The mixed raw material is then subjected to melting, spinning, hydrogen crushing, air jet milling, pressing, sintering and heat treatment in sequence to obtain a cerium iron boron blank.

[0017] S2. The cerium iron boron blank is permeation treated to obtain a high-temperature resistant cerium iron boron magnet.

[0018] In some specific embodiments, step S2 further includes: performing a surface anti-rust treatment on the magnet after the penetration treatment, wherein the surface anti-rust treatment is electroplating with blue-white zinc, electroplating with nickel-copper, or surface bluing treatment.

[0019] In some specific embodiments, in step S1, the sintering includes low-temperature sintering and high-temperature sintering, and the vacuum degree of the sintering is not higher than 3 × 10⁻⁶. -2 Pa, the low-temperature sintering temperature is 300~500℃, the high-temperature sintering temperature is 1000~1100℃, and the holding time is 5~8h; and / or, in step S1, the heat treatment includes primary tempering and secondary tempering, the primary tempering temperature is 800~1000℃, the holding time is 2~4h, and the secondary tempering temperature is 600~700℃, the holding time is 2~4h;

[0020] In step S2, the metal element in the infiltration treatment includes dysprosium, and / or the heat treatment of the infiltration treatment includes a primary heat treatment and a secondary heat treatment. The temperature of the primary heat treatment is 800~1000℃ and the holding time is 12~18h. The temperature of the secondary heat treatment is 600~700℃ and the holding time is 5~10h. The cooling atmosphere of the heat treatment is a protective atmosphere, and the furnace is cooled to 80~90℃ before being taken out.

[0021] This application also provides the application of the high-temperature resistant cerium iron boron magnet described in the above scheme or the high-temperature resistant cerium iron boron magnet prepared by the preparation method described in the above scheme in rare earth permanent magnet motors.

[0022] This application provides a high-temperature resistant cerium iron boron magnet, which is as shown in formula (RE, Ce). x Fe bal M y B z As shown, the introduction of rare earth elements Gd and Ho into this cerium-iron-boron magnet effectively promotes the directional growth of the main phase grains by replacing some of the metals Ce or Pr and Nd with Ho. This also allows the RE-rich phase to be more uniformly distributed at the grain boundaries and junctions of the main phase, improving the microstructure of the cerium-iron-boron magnet and resulting in a higher degree of densification. Ultimately, this enhances the intrinsic coercivity and temperature resistance of the magnet. Furthermore, the high Curie temperature of rare earth element Gd contributes to its high temperature resistance, enabling the magnet to form a more stable crystal lattice. The structure suppresses high-temperature demagnetization and also helps improve the high temperature resistance of cerium-iron-boron magnets. Furthermore, the introduction of Ho and Gd improves the temperature resistance of cerium-iron-boron magnets by improving the permeability Pc and inflection point position. Compared with traditional neodymium-iron-boron magnets, cerium-iron-boron magnets introduce more rare earth element cerium. Since the magnetic polarization intensity of cerium is relatively low compared with neodymium, the remanence is also low. However, by matching other elements and their contents, the resulting cerium-iron-boron magnets can also ensure remanence. Ultimately, the resulting cerium-iron-boron magnets not only meet the remanence requirements but also have high intrinsic coercivity and high temperature resistance.

[0023] In addition, the cerium iron boron magnet provided in this application uses cerium as the main rare earth element, which reduces the production cost compared to neodymium iron boron magnets. While bypassing the bottleneck of neodymium iron boron reserves, it meets the requirements of high temperature resistance for magnets used in rare earth permanent magnet motors. Detailed Implementation

[0024] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0025] Given the low magnetic properties of existing cerium-iron-boron (CFeB) magnets and the requirement for high temperature resistance, this application provides a high-temperature-resistant CFeB magnet. By introducing Gd and Ho into the CFeB magnet, its high temperature resistance is improved. Simultaneously, the controlled content of each element in the CFeB magnet ensures that its magnetic properties meet the application requirements. Specifically, this invention discloses a high-temperature-resistant CFeB magnet as shown in formula (Ⅰ).

[0026] (RE, Ce) x Febal M y B z (I);

[0027] RE is selected from one or two of Gd and Ho and one or more of Pr, Nd, Dy, La, Tb and Y;

[0028] M is selected from one or more of Al, Co, Cu, Ga, Ti, and Zr;

[0029] x, y, and z are the mass percentages of the corresponding elements, with 29%≤x≤33%, 0.1%≤y≤2%, and 0.89%≤z≤1%. The mass percentage of Ce is greater than the mass percentage of RE.

[0030] In the high-temperature resistant cerium-iron-boron magnet provided in this application, Ce is the main rare earth element, and its content is higher than that of other rare earth elements, that is, the mass percentage of Ce is greater than the mass percentage of RE. In some specific embodiments, the Ce content is 15~18wt%, and in some specific embodiments, the Ce content is 16~17wt%.

[0031] In this application, RE is selected from one or two of Gd and Ho and one or more of Pr, Nd, Dy, La, Tb and Y; in some specific embodiments, RE is selected from one or more of Pr, Nd, Dy, La, Tb and Y and Gd; in some specific embodiments, RE is selected from one or more of Pr, Nd, Dy, La, Tb and Y and Ho; in some specific embodiments, RE is selected from one or more of Pr, Nd, Dy, La, Tb and Y and Gd and Ho; in some specific embodiments, RE is selected from Gd, Ho, Pr and Nd.

[0032] In some specific embodiments, for the RE element, the content of Gd is 2-6 wt%, the content of Ho is 1-2 wt%, and the total content of Pr and Nd is 4-13 wt%. In this application, replacing part of the metal Ce or Pr and Nd with Ho can effectively promote the directional growth of the main phase grains and make the RE-rich phase more uniformly distributed at the boundaries and junctions of the main phase grains, improving the microstructure of the cerium-iron-boron alloy sheet. This results in a higher degree of densification of the sintered NdFeB permanent magnet with added Ho, thereby improving the intrinsic coercivity and temperature resistance of the sintered magnet. However, an excessively high Ho content will reduce the remanence of the magnet. In some specific embodiments, the Ho content is 1 wt%. Gd has a high Curie temperature, and its introduction into the cerium-iron-boron magnet can form a more stable lattice structure, suppress high-temperature demagnetization, and improve the high temperature resistance of the cerium-iron-boron magnet. For example, the Gd content is 3 wt%, 4 wt%, 5 wt%, and 6 wt%.

[0033] In some specific embodiments, the total content of Pr and Nd is 4 to 13 wt%, for example, the total content of Pr and Nd is 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, and 12 wt%.

[0034] M is selected from one or more of Al, Co, Cu, Ga, Ti, and Zr; in some specific embodiments, M is selected from one, two, three, four, five, or six of Al, Co, Cu, Ga, Ti, and Zr; in some specific embodiments, M is selected from Al, Co, Cu, and Ga. The mass percentage content of element M is represented by y, which ranges from 0.1% to 2%, from 0.5% to 1.5% in some specific embodiments, from 0.8% to 1.2% in some specific embodiments, and from 0.9% to 1.1% in some specific embodiments.

[0035] The mass percentage of element B is represented by z, which ranges from 0.89% to 1%. In some specific embodiments, z ranges from 0.90% to 0.96%, from 0.91% to 0.95%, and from 0.92% to 0.94%.

[0036] In high-temperature cerium-iron-boron magnets, the mass percentages of rare earth elements (RE, Ce), M, and B correspond to x, y, and z, respectively, with Fe as the balance. For the magnet material, x ranges from 29% to 33%. For example, the RE elements could be Gd, Ho, Pr, and Nd, and the ranges for these four elements and Ce can also be selected within this range, but x must be maintained at 29% to 33% to ensure the effectiveness of the cerium-iron-boron magnet.

[0037] Furthermore, this application also provides a method for preparing the above-mentioned high-temperature-resistant cerium-iron-boron magnet, comprising the following steps:

[0038] S1. The high-temperature resistant cerium iron boron magnet is prepared according to the above-described composition ratio, and the mixture is mixed to obtain a mixed raw material. The mixed raw material is then subjected to melting, spinning, hydrogen crushing, air jet milling, pressing, sintering and heat treatment in sequence to obtain a cerium iron boron blank.

[0039] S2. The cerium iron boron blank is subjected to infiltration treatment and then heat treatment to obtain a high-temperature resistant cerium iron boron magnet.

[0040] In the preparation method of high-temperature resistant cerium iron boron magnets, the melting in step S1 is a well-known technique, and this application does not impose any special restrictions on its specific implementation process. In some specific embodiments, the melting is carried out in a vacuum induction melting furnace, and argon gas is introduced for protection after vacuuming. The melting temperature is 1460~1650℃, and in some specific embodiments, the melting temperature is 1500~1600℃. The belt casting is a well-known technique, and this application does not impose any special restrictions on its specific implementation process. For example, the rapid solidification belt casting method can be used to pour molten alloy liquid onto a high-speed rotating water-cooled copper roller, and the molten alloy liquid is instantly cooled into a rapid solidification sheet of 0.1~0.5mm. The linear velocity of the water-cooled copper roller is 1~5m / s, and in some specific embodiments, the linear velocity of the water-cooled copper roller is 2~3m / s. In some specific embodiments, the thickness of the rapid solidification sheet is 0.3~0.4mm.

[0041] Following the above-mentioned strip spinning, the alloy sheets obtained from the strip spinning are subjected to hydrogen crushing. That is, the strip spinning is loaded into a hydrogen crushing furnace, vacuumed, and high-purity hydrogen is introduced to cause the alloy to absorb hydrogen and form hydrides. The volume expansion causes the alloy sheets to break along the grain boundaries. Subsequently, a dehydrogenation treatment is performed, and after cooling, coarse powder with a particle size of 100~250μm is obtained. In the above steps, the temperature of the dehydrogenation treatment is 500~600℃. In some specific embodiments, the temperature of the dehydrogenation treatment is 550~580℃, and the particle size of the coarse powder is 150~200μm.

[0042] According to the present invention, after hydrogenation, the coarse powder obtained above is subjected to an air jet mill. The air jet mill uses high-pressure nitrogen gas at a pressure of 0.6~0.8 MPa to accelerate the hydrogen-crushed coarse powder to supersonic speeds, causing the particles to collide and break apart in the crushing zone. Then, the particles are classified by centrifugal force using a sorting wheel. Qualified fine powder enters the collection system, while the coarse powder is returned to the crushing zone for further crushing, ultimately obtaining fine powder with a particle size D50 of 3.8~4.5 μm and a morphology tending towards spherical or elliptical. In some specific embodiments of the air jet milling step, the pressure of the high-pressure nitrogen gas is 0.7~0.8 MPa, and the particle size D50 of the fine powder is 4.0~4.3 μm.

[0043] Following the air jet milling process, the fine powder obtained from the air jet mill is pressed into shape. Specifically, the fine powder is loaded into a mold cavity, and the easy magnetization axis (C-axis) of the grains is aligned under a strong magnetic field of 1.5~2.0T. Simultaneously, a pressure of 150~300MPa is applied to shape the powder. After demagnetization and demolding, the powder is vacuum-sealed and then uniformly pressurized in an isostatic press with a liquid pressure of 200~300MPa, ultimately achieving a green compact density of 3.9~4.6 g / cm³. 3The entire process, from powder discharge to pressing completion, must be conducted in an air-isolated environment, with oxygen content strictly controlled below 100 ppm. Furthermore, the magnetic field strength must be sufficiently high to ensure high orientation and prevent a decrease in magnetic properties due to oxidation or insufficient orientation, ultimately yielding a cerium-iron-boron green compact. In some specific embodiments, the molding pressure and the liquid pressure are both 200-260 MPa.

[0044] After forming, the resulting cerium-iron-boron green blank is sintered and heat-treated. The sintering includes low-temperature sintering and high-temperature sintering, and the vacuum degree of the sintering is not higher than 3 × 10⁻⁶. -2 Pa, the low-temperature sintering temperature is 300~500℃, the high-temperature sintering temperature is 1000~1100℃, and the high-temperature sintering holding time is 5~8h; in some specific embodiments, the vacuum degree of sintering is 2×10 -2 Pa ~ 2.5 × 10 -2 Pa, the low-temperature sintering temperature is 320~400℃, the high-temperature sintering temperature is 1030~1080℃, and the holding time for the high-temperature sintering is 6~7h. After sintering, argon gas is introduced for rapid cooling followed by heat treatment. In some specific embodiments, the heat treatment includes a first-stage tempering and a second-stage tempering. The first-stage tempering temperature is 800~1000℃, and the holding time is 2~4h; the second-stage tempering temperature is 600~700℃, and the holding time is 2~4h. In some specific embodiments, the first-stage tempering temperature is 820~900℃, and the holding time is 2.5~3h; the second-stage tempering temperature is 640~680℃, and the holding time is 2.5~3h. After the above series of treatments, a cerium-iron-boron blank is obtained.

[0045] In step S2, the cerium iron boron blank is subjected to heat treatment after infiltration treatment to obtain a high-temperature resistant cerium iron boron magnet. In some specific embodiments, the element infiltration treatment is the rare earth element dysprosium. In some specific embodiments, the infiltration treatment specifically involves placing the cerium iron boron blank in a nitrogen atmosphere and uniformly spraying dysprosium slurry onto the surface of the blank using a spray gun. The blank obtained after spraying has a weight increase of 0.5~1.5wt% compared to the blank before spraying. In some specific embodiments, the weight increase is 1.0wt%. After the sprayed slurry dries, it undergoes heat treatment, which includes a primary heat treatment and a secondary heat treatment. The primary heat treatment is performed at a temperature of 800-1000℃ for 12-18 hours, and the secondary heat treatment is performed at a temperature of 600-700℃ for 5-10 hours. The cooling atmosphere for the heat treatment is a protective atmosphere, and the material is cooled in the furnace to 80-90℃ before being removed from the furnace. In some specific embodiments, the primary heat treatment is performed at a temperature of 850-900℃ for 13-15 hours, and the secondary heat treatment is performed at a temperature of 640-680℃ for 6-8 hours.

[0046] In some specific embodiments, the infiltration treatment further includes a surface rust prevention treatment; in some specific embodiments, the surface rust prevention treatment is electroplating with blue-white zinc, electroplating with nickel-copper, or surface bluing treatment; the specific implementation methods of the above surface rust prevention treatment are in accordance with those well known to those skilled in the art, and this application does not impose any special limitations on them.

[0047] Furthermore, this application also provides the application of the aforementioned cerium iron boron magnet in rare earth permanent magnet motors.

[0048] Specifically, the rare earth permanent magnet motor is a rare earth permanent magnet motor well known to those skilled in the art. This application does not adjust its structure, but only adjusts the original magnet material to the cerium iron boron magnet material described in the above scheme.

[0049] The cerium-iron-boron magnet provided in this application uses Ce as the main rare earth element, while introducing Gd, Ho and other rare earth elements and limiting the content of each element, giving the magnet material the following advantages:

[0050] 1) The introduction of rare earth elements Gd and Ho improves the temperature resistance of cerium iron boron magnets. The substitution of some metals Ce or Pr and Nd by rare earth element Ho can effectively promote the directional growth of the main phase grains and make the RE-rich phase more uniformly distributed at the boundaries and junctions of the main phase grains, improving the microstructure of cerium iron boron alloy sheets. This results in a higher degree of densification of sintered NdFeB permanent magnets with added Ho, thereby improving the intrinsic coercivity and temperature resistance of the sintered magnets. Rare earth element Gd has a high Curie temperature, thus possessing high temperature resistance. After adding the high-temperature-resistant element Gd, the magnet can form a more stable crystal structure, suppressing high-temperature demagnetization and improving high-temperature resistance.

[0051] 2) For cerium iron boron (CFeB) magnets, the introduction of Ho and Gd improves the permeability Pc and inflection point, thus enhancing their temperature resistance. Compared to traditional neodymium iron boron (NdFeB) magnets, CFeB magnets incorporate more rare-earth element cerium, resulting in relatively lower remanence, a smaller demagnetization inflection point, and better temperature resistance. While CFeB magnets have lower remanence (still meeting performance requirements) compared to NdFeB magnets with the same magnetic moment and coercivity, the permeability Pc can be increased by increasing the thickness along the magnetization direction during product design, thereby improving high temperature resistance. This allows for a smaller demagnetization inflection point and better temperature resistance while maintaining a constant magnetic moment. In applications requiring high temperature resistance, such as rare-earth permanent magnet motors, CFeB magnets offer significant advantages over NdFeB magnets.

[0052] 3) Replacing neodymium with the rare earth element cerium solves the limitations of neodymium in terms of abundance and reserves, and reduces the production cost of rare earth permanent magnet materials. In this invention, the content of metallic cerium is greater than that of metallic neodymium, forming a cerium-iron-boron magnet, which reduces the raw material cost of the magnet. While bypassing the bottleneck of neodymium-iron-boron reserves, it meets the requirements for high temperature resistance in the practical application of rare earth permanent magnet motors, fully promotes the comprehensive and balanced utilization of rare earth resources, and provides a feasible solution to the non-renewable problem of neodymium-iron-boron rare earth permanent magnets.

[0053] To further understand the present invention, the high-temperature resistant cerium iron boron magnet and its preparation method provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0054] Example 1

[0055] This embodiment provides a high-temperature resistant cerium-iron-boron magnet, wherein rare earth Gd accounts for 1 wt% and rare earth Ho accounts for 1 wt%; the magnet composition is: Ce 16 Gd1Ho1(PrNd) 13 Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0056] S1) Calculate and weigh the raw materials according to the above components and their mass percentages. Before weighing, remove the oxide layer on the surface of raw materials such as pure iron. Then use a high-precision electronic balance to weigh each component according to the formula. The purity of the raw materials must reach 99.9% or more, and the weighing accuracy must be controlled within ±0.1% to ensure the accuracy of the final magnet composition.

[0057] S2) Place the prepared raw materials into a vacuum induction melting furnace, and after evacuation, fill it with argon gas for protection. Heat it to 1460~1650℃ to completely melt the raw materials. Use the rapid solidification casting method to pour the alloy liquid onto a high-speed rotating water-cooled copper roller. The linear speed of the water-cooled copper roller is 2m / s. The alloy liquid is instantly cooled to form a rapid solidification sheet with a thickness of 0.3mm, resulting in a cerium-iron-boron rapid solidification alloy sheet with uniform thickness and no pores or oxide scale.

[0058] S3) After loading the cerium-iron-boron rapid solidification alloy flakes into the hydrogen crushing furnace, a vacuum was drawn and high-purity hydrogen was introduced to make the alloy absorb hydrogen and form hydrides. The volume expansion caused the alloy flakes to break along the grain boundaries. Then, dehydrogenation treatment was carried out at a high temperature of 550℃. After cooling, coarse powder with a particle size of about 150μm was obtained.

[0059] S4) High-pressure nitrogen gas at a pressure of 0.8 MPa is used to accelerate the coarse powder to supersonic speed, causing the particles to collide and break each other in the crushing zone. Then, the particles are classified by centrifugal force through a sorting wheel. The qualified fine powder enters the collection system, while the coarse powder is returned to the crushing zone for further crushing. Finally, fine powder with a particle size D50 of about 4.0 μm and a morphology that tends to be spherical or elliptical is obtained.

[0060] S5) The micron-sized powder obtained by air jet milling is loaded into the mold cavity. Under a strong magnetic field of over 1.8T, the easy magnetization axis (C-axis) of the grains is aligned. Simultaneously, a pressure of 200MPa is applied for forming. After demagnetization and demolding, it is vacuum-sealed and then uniformly pressurized in an isostatic press with a liquid pressure of 200MPa, ultimately achieving a green compact density of approximately 4.2 g / cm³. 3 The entire process from powder discharge to pressing must be airtight, with oxygen content strictly controlled below 100ppm, and the magnetic field strength must be high enough to ensure high orientation, avoiding a decrease in magnetic properties due to oxidation or insufficient orientation, and finally obtaining cerium iron boron green blanks.

[0061] S6) The pressed cerium-iron-boron green blank is subjected to a vacuum degree not exceeding 3×10 -2 In a Pa sintering furnace, the green body is first heated to 400°C to remove the depressurizing agent, and then sintered under a vacuum of 2×10⁻⁶. -2 High-temperature sintering was performed at 1080℃ for 6 hours to densify the magnet. After rapid cooling with argon gas, a first-stage tempering was carried out, followed by holding at 900℃ for 3 hours and then holding at 640℃ for 3 hours for a second-stage tempering, ultimately yielding a magnet with a density of approximately 7.6 g / cm³. 3 Cerium iron boron blank;

[0062] S7) The cerium iron boron blank is processed by a slicing machine to obtain a cerium iron boron square sheet magnet with a specification of 35mm×14mm×3mm;

[0063] S8) The obtained square magnet column was placed in a nitrogen atmosphere, and dysprosium slurry was evenly sprayed onto the surface of the square magnet using a spray gun. The weight gain of the spraying was controlled to be 1%. After drying, the obtained square magnet was placed in a vacuum sintering furnace for heat treatment. It was kept at 900℃ for 15 hours and at 640℃ for 6 hours. After the heat treatment was completed, argon gas was introduced and the magnet was cooled to below 85℃ before being taken out of the furnace to obtain a cerium iron boron square magnet.

[0064] S9) After the square magnet obtained above is polished with a surface grinder, it is placed in a chamfering machine to blunt the sharp corners, and then the magnet is subjected to anti-rust surface treatment. After the surface treatment is completed, the cerium iron boron square magnet is obtained.

[0065] Performance testing:

[0066] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0067] The obtained φ10mm×9mm test sample column was placed in the AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this embodiment were obtained, and the results are shown in Table 1.

[0068] Example 2

[0069] This embodiment provides a high-temperature resistant cerium iron boron magnet, which differs from Embodiment 1 in that the component content of the cerium iron boron magnet has been adjusted, with rare earth Gd accounting for 2wt% and rare earth Ho accounting for 1wt%; the magnet component is: Ce 16 Gd2Ho1(PrNd) 12 Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0070] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0071] Performance testing:

[0072] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0073] The obtained φ10mm×9mm test sample column was placed in the AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this embodiment were obtained, and the results are shown in Table 1.

[0074] Example 3

[0075] This embodiment provides a high-temperature resistant cerium iron boron magnet, which differs from Embodiment 1 in that the component content of the cerium iron boron magnet has been adjusted, with rare earth Gd accounting for 3wt% and rare earth Ho accounting for 1wt%; the magnet component is: Ce 16 Gd3Ho1(PrNd) 11 Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0076] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0077] Performance testing:

[0078] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0079] The obtained φ10mm×9mm test sample column was placed in the AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this embodiment were obtained, and the results are shown in Table 1.

[0080] Example 4

[0081] This embodiment provides a high-temperature resistant cerium iron boron magnet, which differs from Embodiment 1 in that the component content of the cerium iron boron magnet has been adjusted, with rare earth Gd accounting for 4wt% and rare earth Ho accounting for 1wt%; the magnet component is: Ce 16 Gd4Ho1(PrNd) 10 Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0082] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0083] Performance testing:

[0084] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0085] The obtained φ10mm×9mm test sample column was placed in the AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this embodiment were obtained, and the results are shown in Table 1.

[0086] Example 5

[0087] This embodiment provides a high-temperature resistant cerium iron boron magnet, which differs from Embodiment 1 in that the component content of the cerium iron boron magnet has been adjusted, with rare earth Gd accounting for 5wt% and rare earth Ho accounting for 1wt%; the magnet component is: Ce 16 Gd5Ho1(PrNd)9Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0088] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0089] Performance testing:

[0090] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0091] The obtained φ10mm×9mm test sample column was placed in the AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this embodiment were obtained, and the results are shown in Table 1.

[0092] Example 6

[0093] This embodiment provides a high-temperature resistant cerium iron boron magnet, which differs from Embodiment 1 in that the component content of the cerium iron boron magnet has been adjusted, with rare earth Gd accounting for 6wt% and rare earth Ho accounting for 1wt%; the magnet component is: Ce 16 Gd6Ho1(PrNd)8Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0094] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0095] Performance testing:

[0096] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0097] The obtained φ10mm×9mm test sample column was placed in the AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this embodiment were obtained, and the results are shown in Table 1.

[0098] Example 7

[0099] This embodiment provides a high-temperature resistant cerium iron boron magnet, which differs from Embodiment 1 in that the component content of the cerium iron boron magnet has been adjusted, with rare earth Gd accounting for 5wt% and rare earth Ho accounting for 2wt%; the magnet component is: Ce 16 Gd5Ho2(PrNd)8Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0100] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0101] Performance testing:

[0102] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0103] The obtained φ10mm×9mm test sample column was placed in the AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this embodiment were obtained, and the results are shown in Table 1.

[0104] Example 8

[0105] This embodiment provides a high-temperature resistant cerium iron boron magnet, which differs from Embodiment 1 in that the component content of the cerium iron boron magnet has been adjusted, with rare earth Gd accounting for 5wt% and rare earth Ho accounting for 3wt%; the magnet component is: Ce 16 Gd5Ho3(PrNd)7Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0106] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0107] Performance testing:

[0108] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0109] The obtained φ10mm×9mm test sample column was placed in the AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this embodiment were obtained, and the results are shown in Table 1.

[0110] Example 9

[0111] This embodiment provides a high-temperature resistant cerium iron boron magnet, which differs from Embodiment 1 in that the component content of the cerium iron boron magnet has been adjusted, with rare earth Gd accounting for 5wt% and rare earth Ho accounting for 4wt%; the magnet component is: Ce 16 Gd5Ho4(PrNd)6Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0112] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0113] Performance testing:

[0114] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0115] The obtained φ10mm×9mm test sample column was placed in the AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this embodiment were obtained, and the results are shown in Table 1.

[0116] Example 10

[0117] This embodiment provides a high-temperature resistant cerium iron boron magnet, which differs from Embodiment 1 in that the component content of the cerium iron boron magnet has been adjusted, with rare earth Gd accounting for 5 wt% and rare earth Ho accounting for 5 wt%; the magnet component is: Ce 16 Gd5Ho5(PrNd)5Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0118] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0119] Performance testing:

[0120] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0121] The obtained φ10mm×9mm test sample column was placed in the AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this embodiment were obtained, and the results are shown in Table 1.

[0122] Comparative Example 1

[0123] This comparative example provides a high-temperature resistant cerium iron boron magnet, which differs from Example 1 in that the component content of the cerium iron boron magnet has been adjusted, with rare earth Gd accounting for 5 wt% and rare earth Ho accounting for 6 wt%; the magnet component is: Ce 16 Gd5Ho6(PrNd)4Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0124] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0125] Performance testing:

[0126] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0127] The obtained φ10mm×9mm test sample column was placed in an AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this comparative example were obtained, and the results are shown in Table 1.

[0128] Comparative Example 2

[0129] This comparative example provides a neodymium iron boron magnet that does not contain rare earth elements Ce, Gd, and Ho; the magnet composition is (PrNd). 31 Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0130] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0131] Performance testing:

[0132] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0133] The obtained φ10mm×9mm test sample column was placed in an AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the neodymium iron boron magnet prepared in this comparative example were obtained, and the results are shown in Table 1.

[0134] Comparative Example 3

[0135] This comparative example provides a cerium-iron-boron magnet that does not contain rare earth elements Gd and Ho; the magnet composition is: Ce 16 (PrNd) 15 Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0136] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0137] Performance testing:

[0138] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0139] The obtained φ10mm×9mm test sample column was placed in an AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this comparative example were obtained, and the results are shown in Table 1.

[0140] Comparative Example 4

[0141] This comparative example provides a cerium-iron-boron magnet that does not contain rare-earth Gd; the magnet composition is: Ce 16 Ho1(PrNd) 14 Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0142] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0143] Performance testing:

[0144] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0145] The obtained φ10mm×9mm test sample column was placed in an AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this comparative example were obtained, and the results are shown in Table 1.

[0146] Comparative Example 5

[0147] This comparative example provides a cerium-iron-boron magnet that does not contain rare-earth Ho; the magnet composition is: Ce 16 Gd5(PrNd) 10 Fe 67.28 Al 0.3 Co 0.3 Cu 0.1 Ga 0.1 B 0.92 ;

[0148] Steps S1) to S9) in the preparation method are the same as in Example 1.

[0149] Performance testing:

[0150] The square magnet obtained in step S9) is processed into a cylindrical sheet with a size of φ10mm×3mm using an electrical discharge wire cutting machine. The three cylindrical sheets are stacked to obtain a test sample column with a size of φ10mm×9mm.

[0151] The obtained φ10mm×9mm test sample column was placed in an AMT-4 permanent magnet automatic measuring instrument for magnetic performance testing. The performance data of the cerium iron boron magnet prepared in this comparative example were obtained, and the results are shown in Table 1.

[0152] The data obtained from the above embodiments and comparative tests are compiled into Table 1. In the table, the remanence temperature coefficient α and coercivity temperature coefficient β are used as key indicators for evaluating NdFeB permanent magnet materials, which directly reflect the thermal stability of NdFeB. However, due to the high-temperature demagnetization characteristics of NdFeB permanent magnet materials, α and β are usually negative; the better the temperature stability, the closer the temperature coefficient is to 0.

[0153]

[0154] As shown in the table above, adjusting the proportion of rare earth elements in the magnet reduces both the coercivity temperature coefficient and the remanence temperature coefficient, thus enhancing temperature stability. This application's embodiments use cerium to replace neodymium, and simultaneously introduce rare earth elements Gd and Ho to improve the magnetic properties of the cerium-iron-boron magnet, improving the permeability Pc and inflection point position, thereby enabling the cerium-iron-boron magnet to achieve magnetic properties that meet practical application requirements. Regarding temperature coefficients, the data from these embodiments are superior to those of the conventional neodymium-iron-boron magnet in Comparative Example 2. Example 5 is a preferred example, exhibiting a significant advantage in temperature coefficient and excellent temperature resistance, sufficient to meet the practical applications of rare earth permanent magnet motors. Further increases in the content of Gd and / or Ho will reduce both magnetic properties and temperature resistance.

[0155] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0156] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-temperature-resistant cerium-iron-boron magnet as shown in formula (Ⅰ), (RE,Ce) x Fe bal M y B z (Ⅰ); in, RE is selected from one or both of Gd and Ho and one or more of Pr, Nd, Dy, La, Tb and Y; M is selected from one or more of Al, Co, Cu, Ga, Ti, and Zr; x, y, and z are the mass percentages of the corresponding elements, with 29%≤x≤33%, 0.1%≤y≤2%, and 0.89%≤z≤1%. The mass percentage of Ce is greater than the mass percentage of RE.

2. The high-temperature resistant cerium iron boron magnet according to claim 1, characterized in that, The RE is selected from Gd, Ho, Pr and Nd.

3. The high-temperature resistant cerium iron boron magnet according to claim 1 or 2, characterized in that, The content of Gd is 2-6 wt%, and the content of Ho is 1-2 wt%.

4. The high-temperature resistant cerium iron boron magnet according to claim 3, characterized in that, The Ce content is 15-18 wt%, and / or the total Pr and Nd content is 4-13 wt%.

5. The high-temperature resistant cerium iron boron magnet according to claim 3, characterized in that, M is selected from Al, Co, Cu and Ga.

6. The high-temperature resistant cerium iron boron magnet according to claim 1 or 4, characterized in that, y is 0.5%~1.5%, and / or z is 0.90%~0.96%.

7. The method for preparing the high-temperature resistant cerium iron boron magnet according to claim 1, comprising the following steps: S1. The high-temperature resistant cerium iron boron magnet is prepared according to the component ratio of claim 1, and the mixture is mixed to obtain a mixed raw material. The mixed raw material is then subjected to melting, strip spinning, hydrogen crushing, air jet milling, pressing, sintering and heat treatment in sequence to obtain a cerium iron boron blank. S2. The cerium iron boron blank is permeation treated to obtain a high-temperature resistant cerium iron boron magnet.

8. The preparation method according to claim 7, characterized in that, In step S2, the process after the penetration treatment further includes: performing a surface anti-rust treatment on the magnet after the penetration treatment, wherein the surface anti-rust treatment is electroplating with blue-white zinc, electroplating with nickel-copper, or surface bluing treatment.

9. The preparation method according to claim 7, characterized in that, In step S1, the sintering includes low-temperature sintering and high-temperature sintering, and the vacuum degree of the sintering is not higher than 3×10⁻⁶. -2 Pa, the low-temperature sintering temperature is 300~500℃, the high-temperature sintering temperature is 1000~1100℃, and the high-temperature sintering holding time is 5~8h; and / or, in step S1, the heat treatment includes primary tempering and secondary tempering, the primary tempering temperature is 800~1000℃, the holding time is 2~4h, and the secondary tempering temperature is 600~700℃, the holding time is 2~4h; In step S2, the metal element in the infiltration treatment includes dysprosium, and / or the heat treatment of the infiltration treatment includes a primary heat treatment and a secondary heat treatment. The temperature of the primary heat treatment is 800~1000℃ and the holding time is 12~18h. The temperature of the secondary heat treatment is 600~700℃ and the holding time is 5~10h. The cooling atmosphere of the heat treatment is a protective atmosphere, and the furnace is cooled to 80~90℃ before being taken out.

10. The application of the high-temperature resistant cerium iron boron magnet according to any one of claims 1 to 6 or the high-temperature resistant cerium iron boron magnet prepared by the preparation method according to any one of claims 7 to 9 in rare earth permanent magnet motors.

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