Preparation method of high-abundance cerium-iron-boron permanent magnet material

Abstract

The invention relates to a preparation method of a high-abundance cerium-iron-boron permanent magnet material, and belongs to the technical field of rare earth permanent magnet materials. Comprising the following steps that S1, a base material is pretreated, 25wt% of the sintered neodymium-iron-boron magnet is immersed in a pickling solution to be subjected to ultrasonic pickling treatment, and vacuum drying is performed after deionized water flushing; s2, preparing diffusion source slurry; s3, spraying the diffusion source slurry; s4, grain boundary diffusion treatment; and S5, aging treatment. According to the preparation method of the high-abundance cerium-iron-boron permanent magnet material, through the synergistic effect of the precise grain boundary diffusion control technology and the efficient coating preparation technology, efficient utilization of heavy rare earth elements is achieved, the use amount of the heavy rare earth is reduced, the resource pressure is relieved, the traditional heavy rare earth distribution mode is changed, the unique process is integrated and innovated, and the high-abundance cerium-iron-boron permanent magnet material is obtained. Synergistic interaction of all links is realized, the product quality and the production efficiency are improved, the production cost is reduced, and the product cost performance is improved.

Description

TECHNICAL FIELD

[0001] The application relates to a high-abundance cerium-iron-boron permanent magnet material preparation method and belongs to the technical field of rare earth permanent magnet materials. BACKGROUND

[0002] Rare earth permanent magnet materials are currently the most widely used and best magnetic performance permanent magnet materials, and are widely used in new energy vehicles, wind power generation, electronic information, and instruments and meters and the like. However, the utilization of rare earth resources is extremely unbalanced, and the application range of high-abundance rare earth elements such as lanthanum and cerium is relatively small, while praseodymium-neodymium alloy and dysprosium-terbium has a wide range of applications, resulting in a large amount of high-abundance rare earth elements such as lanthanum and cerium accumulated due to associated mining and refining. The emergence of rare earth cerium magnets can optimize the utilization of rare earth resources while reducing costs.

[0003] In the field of sintered neodymium-iron-boron magnetic materials, although high-abundance cerium-iron-boron permanent magnet materials have excellent comprehensive magnetic properties and are widely used in many key fields, the utilization of rare earth resources in China is seriously unbalanced. In the permanent magnet industry, the consumption of Pr and Nd is more than 80%, while the high-abundance La, Ce and Y associated with them are rarely used. The requirements for the coercivity and temperature resistance of magnets in emerging fields are continuously rising, further exacerbating the consumption of heavy rare earths such as Dy and Tb, and there are problems of resource shortage, high cost and low performance-price ratio. Based on this, the application provides a high-abundance cerium-iron-boron permanent magnet material preparation method. SUMMARY

[0004] Therefore, the application provides a high-abundance cerium-iron-boron permanent magnet material preparation method, which is expected to reduce the use of heavy rare earths, alleviate resource pressure, reduce production costs, and improve the performance-price ratio of products.

[0005] The application provides a high-abundance cerium-iron-boron permanent magnet material preparation method, and the technical scheme provided is as follows:

[0006] S1: substrate pretreatment: sintered neodymium-iron-boron magnets with a cerium content of >25wt% are immersed in an acid pickling solution for ultrasonic acid pickling treatment, rinsed with deionized water and vacuum dried;

[0007] S2: diffusion source slurry preparation: DyF3 / Tb4O7 composite powder is mixed with anhydrous ethanol in a certain proportion to form a nanoscale Dy2O3 suspension, and nanoscale Dy2O3 is ultrasonically dispersed with 3wt% PVP binder in isopropyl alcohol, the viscosity is controlled at 50-80mPa·s, and a diffusion source slurry is obtained;

[0008] S3: diffusion source slurry spraying: the diffusion source slurry is sprayed on the surface of the substrate by a high-voltage electrostatic spraying process to form a uniform Dy2O3-PVP composite coating, and the coating magnet is obtained after curing at 150℃ for 30min;

[0009] S4: Grain boundary diffusion treatment: the coating magnet is placed in a vacuum heat treatment furnace, Ar / H2 mixed gas is introduced for reduction diffusion, gradient temperature control is performed in the vacuum heat treatment furnace, and the grain boundary diffusion is accurately controlled;

[0010] S5: Aging treatment: 850 DEG C is rapidly cooled to 500 DEG C, and the microstructure of the magnet is optimized, so that a high-abundance cerium iron boron permanent magnet material is obtained.

[0011] Further, the acid pickling solution in step S1 is 0.5-1.0 mol / L nitric acid solution, the ultrasonic acid pickling treatment time is 5-10 min, and the vacuum drying temperature is 80 DEG C.

[0012] Further, the mass ratio of the DyF3 / Tb4O7 composite powder in step S2 is 3:1, and the DyF3 / Tb4O7 composite powder with a mass ratio of 3:1 is mixed with anhydrous ethanol in a ratio of 1:3.

[0013] Further, the D50 of the nanoscale Dy2O3 suspension in step S2 is ≤200 nm.

[0014] Further, the voltage of the high-voltage electrostatic spraying in step S3 is 50 kV, the carrier gas pressure is 0.3-0.6 MPa, and the spraying distance is 200-260 mm.

[0015] Further, the thickness of the Dy2O3-PVP composite coating in step S3 is 5-15 μm.

[0016] Further, the mass ratio of the Ar / H2 mixed gas in step S4 is 95:5.

[0017] Further, the gradient temperature control in step S4 is performed under a vacuum degree of <10-3 Pa.

[0018] Further, the gradient temperature control in step S4 has the following two stages:

[0019] Stage 1: heated to 500-550 DEG C at 5 DEG C / min and kept for 1-2 h;

[0020] Stage 2: heated to 800-900 DEG C at 3 DEG C / min and kept for 3-8 h.

[0021] The beneficial effects of the present application are:

[0022] The application provides a high-abundance cerium-iron-boron permanent magnet material preparation method, which realizes efficient use of heavy rare earth elements, reduces the use amount of heavy rare earth, relieves resource pressure, changes a traditional heavy rare earth distribution mode, realizes synergistic effect of each link, improves product quality and production efficiency, reduces production cost, and improves product performance-cost ratio through precise grain boundary diffusion control technology and efficient coating preparation technology. DETAILED DESCRIPTION

[0023] In the present specification, the orientation terms such as up, down, left, right, front, back, front surface, back surface, top, bottom, etc. mentioned or possibly mentioned are defined with respect to its configuration, which are relative concepts. Therefore, it is possible to change accordingly according to different positions, different use states, etc. Therefore, these or other orientation terms should not be interpreted as limiting terms.

[0024] As used in the present specification, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0025] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0026] The preferred embodiments of the present application will be described in detail below.

[0027] The present application provides a high-abundance cerium-iron-boron permanent magnet material preparation method, which comprises the following steps:

[0028] S1: substrate pretreatment: sintered neodymium-iron-boron magnets with a cerium content of >25wt% are immersed in an acid pickling solution for ultrasonic acid pickling treatment, and then washed with deionized water and vacuum dried, the acid pickling solution is a 0.5-1.0mol / L nitric acid solution, the ultrasonic acid pickling treatment time is 5-10min, and the vacuum drying temperature is 80℃;

[0029] S2: diffusion source slurry preparation: DyF3 / Tb4O7 composite powder is mixed with anhydrous ethanol in a certain proportion to form a nanoscale Dy2O3 suspension, the D50 of the nanoscale Dy2O3 suspension is ≤200nm, the mass ratio of the DyF3 / Tb4O7 composite powder is 3:1, the DyF3 / Tb4O7 composite powder with a mass ratio of 3:1 is mixed with anhydrous ethanol in a ratio of 1:3, nanoscale Dy2O3 is ultrasonically dispersed with 3wt% PVP binder in isopropyl alcohol, the viscosity is controlled at 50-80mPa·s, and a diffusion source slurry is obtained;

[0030] S3: Diffusion source slurry spraying: a diffusion source slurry is used to form a uniform Dy2O3-PVP composite coating on the surface of the substrate by a high-voltage electrostatic spraying process, the thickness of the Dy2O3-PVP composite coating is 5-15 μm, the voltage of the high-voltage electrostatic spraying is 50 kV, the carrier gas pressure is 0.3-0.6 MPa, the spraying distance is 200-260 mm, and the coating magnet is obtained after solidification at 150℃ for 30 min, and the porosity is <1%;

[0031] S4: Grain boundary diffusion treatment: the coating magnet is placed in a vacuum heat treatment furnace, and Ar / H2 mixed gas is introduced for reduction diffusion, the mass ratio of Ar / H2 mixed gas is 95:5, gradient temperature control is performed in the vacuum heat treatment furnace to accurately control the grain boundary diffusion, the grain boundary diffusion depth reaches 30-50 μm, the rare earth oxide is inhibited, and the gradient temperature control is performed under a vacuum degree <10-3 Pa, and the gradient temperature control has the following two stages:

[0032] Stage 1: heating at 5℃ / min to 500-550℃ for 1-2 h;

[0033] Stage 2: heating at 3℃ / min to 800-900℃ for 3-8 h;

[0034] S5: aging treatment: 850℃ quenching to 500℃ for 2-4 h, furnace cooling to room temperature, optimizing the microstructure of the magnet, and obtaining a high-abundance cerium-iron-boron permanent magnet material.

[0035] The method realizes efficient utilization of heavy rare earth elements through the synergistic effect of precise grain boundary diffusion control technology and efficient coating preparation technology, expands the deposition range of heavy rare earth elements from the surface of micrograins to the surface of macro magnets, improves the performance of the magnet by grain boundary diffusion, reduces the amount of heavy rare earth elements, relieves resource pressure, changes the traditional distribution mode of heavy rare earth elements, and integrates the unique process innovation: integrates multiple processes such as pickling, drying, spraying, vacuum heat treatment, etc., forms a complete and efficient grain boundary penetration process, realizes the synergistic effect of each link, improves product quality and production efficiency, reduces production cost, improves the performance-price ratio of products, enhances the competitiveness of enterprises in the market, increases the coercive force by 35-50%, and the loss of remanence is <5%. It is suitable for high-performance scenarios such as new energy vehicle motors and wind power equipment, enhances the competitiveness of enterprises in the market, and has far-reaching significance for promoting the sustainable development of the industry.

[0036] The above describes the present application and its embodiments, which are not limiting, and the actual structure is not limited thereto. In general, if a person skilled in the art is inspired by it, without departing from the purpose of the present application, without creative design, similar structure and embodiments to the technical solution can be designed, which should belong to the protection scope of the present application.

Claims

1. A method for preparing high-abundance cerium-iron-boron permanent magnet material, characterized by: The following steps are involved: S1: Substrate pretreatment: immerse the sintered NdFeB magnet with a cerium content greater than 25 wt% in an acid pickling solution for ultrasonic pickling, rinse with deionized water, and then dry in a vacuum oven. S2: Preparation of diffusion source slurry: DyF3 / Tb4O7 composite powder and anhydrous ethanol were mixed in proportion to form a nano-scale Dy2O3 suspension. Nano-Dy2O3 and 3 wt% PVP binder were ultrasonically dispersed in isopropyl alcohol with the viscosity controlled at 50-80 mPa·s to obtain a diffusion source slurry. S3: Diffusion source slurry spraying: A uniform Dy2O3-PVP composite coating is formed on the substrate surface using a diffusion source slurry through a high-voltage electrostatic spraying process, and then cured at 150°C for 30 minutes to obtain a coated magnet; S4: Grain boundary diffusion treatment: Place the coated magnet in a vacuum heat treatment furnace and introduce Ar / H2 mixed gas for reduction diffusion. Gradient temperature control is performed in the vacuum heat treatment furnace to precisely control grain boundary diffusion. S5: Aging treatment: Rapid cooling from 850℃ to 500℃ and keeping warm for 2-4h, then cooling to room temperature with the furnace to optimize the magnet microstructure and obtain high-abundance Cerium Iron Boron permanent magnet material.

2. The method for preparing a high-abundance cerium-iron-boron permanent magnet material according to claim 1, characterized in that: In step S1, the pickling solution is a 0.5-1.0 mol / L nitric acid solution, the ultrasonic pickling treatment time is 5-10 min, and the vacuum drying temperature is 80°C.

3. The method for preparing a high-abundance cerium-iron-boron permanent magnet material according to claim 1, wherein: In step S2, the mass ratio of the DyF3 / Tb4O7 composite powder is 3:1, and the DyF3 / Tb4O7 composite powder with a mass ratio of 3:1 is mixed with anhydrous ethanol in a ratio of 1:

3.

4. The method for preparing a high-abundance cerium-iron-boron permanent magnet material according to claim 1, wherein: The D50 of the nano-scale Dy2O3 suspension in step S2 is ≤ 200 nm.

5. The method for preparing a high-abundance cerium-iron-boron permanent magnet material according to claim 1, characterized in that: In step S3, the voltage of the high-voltage electrostatic spraying is 50 kV, the carrier gas pressure is 0.3-0.6 MPa, and the spray distance is 200-260 mm.

6. The method for preparing a high-abundance cerium-iron-boron permanent magnet material according to claim 1, characterized in that: The thickness of the Dy2O3-PVP composite coating in step S3 is 5-15 μm.

7. The method for preparing a high-abundance cerium-iron-boron permanent magnet material according to claim 1, characterized in that: In step S4, the mass ratio of the Ar / H2 mixed gas is 95:

5.

8. The method for preparing a high-abundance cerium-iron-boron permanent magnet material according to claim 1, characterized in that: In step S4, the gradient temperature control is performed under a vacuum degree of <10-3Pa.

9. The method for preparing a high-abundance cerium-iron-boron permanent magnet material according to claim 1, characterized in that: The gradient temperature control performed in step S4 has the following two stages: Stage 1: heating to 500-550°C at 5°C / min and keeping at this temperature for 1-2h; Stage 2: Raise the temperature to 800-900℃ at 3℃ / min and keep it at this temperature for 3-8h.