EP4379755A1

EP4379755A1 - Samarium-based rare earth permanent magnet material, and preparation method therefor and application thereof

Info

Publication number: EP4379755A1
Application number: EP23826088.9A
Authority: EP
Inventors: Yuping Li; Yongyang SUN; Yuntao Jiang; Yunyi ZHANG; Changzheng GUO
Original assignee: Hengdian Group DMEGC Magnetics Co Ltd
Current assignee: Hengdian Group DMEGC Magnetics Co Ltd
Priority date: 2022-06-20
Filing date: 2023-05-30
Publication date: 2024-06-05
Also published as: WO2023246439A1; CN114974779A

Abstract

Disclosed in the present invention are a samarium-based rare earth permanent magnet material, and a preparation method therefor and an application thereof. In the samarium-based rare earth permanent magnet material Sm2FeαCuβVγMoδNε, 11.5 ≤ α ≤ 17.5, 0.1 ≤ β ≤ 0.4, 1.0 ≤ y ≤ 1.8, 0 ≤ δ ≤ 1.0, and 2.9 ≤ ε ≤ 4.0. According to the samarium-based rare earth permanent magnet material provided by the present application, a good balance of the remanence and the coercivity is promoted by doping with vanadium, copper, and molybdenum and adjusting to an appropriate atomic ratio range, such that the samarium-based rare earth permanent magnet material has excellent comprehensive magnetic performance. The preparation method provided by the present application is simple to operate, low in cost, and suitable for the fields of small and special motors, magnetic sensors, or audio equipment.

Description

TECHNICAL FIELD

Examples of the present application relate to the technical field of magnetic materials, for example, a permanent magnet material, a preparation method therefor and an application thereof, and specifically, a samarium-based rare-earth permanent magnet material, a preparation method therefor and an application thereof.

BACKGROUND

Neodymium-iron-boron rare-earth permanent magnet materials are widely used in fields of vehicles, household appliances and industrial equipment due to the advantages of superhigh remanence, high coercivity and high magnetic energy product. Samarium-based rare-earth permanent magnet materials, represented by a Sm₂Fe₁₇N_x compound, have a higher Curie temperature, higher anisotropy field and similar saturation magnetization compared with the NdFeB permanent magnet materials, and are regarded as having the potential to become a new generation of permanent magnet materials. However, in a case where the temperature is more than or equal to 550°C, the Sm₂Fe₁₇N_x compound will be irreversibly decomposed, and the magnetic properties will be greatly reduced.
CN105355354A discloses a samarium-iron-nitrogen-based anisotropic rare-earth permanent magnet powder and a preparation method therefor. A 2:17-type main phase providing magnetism is wrapped by a low-melting phase composed of element R and element M2, which can not only accommodate excess rare-earth elements in the alloy without forming a SmFe₂ phase or a SmFe₃ phase, but also help the 2: 17-type main-phase grains to eliminate defects, reduce antiphase boundary nucleation sites and decoupling effect. However, the oxidation resistance and magnetic properties of this magnetic powder are still required to be further improved.
CN108994311A discloses a preparation method for an anisotropic high-performance samarium-iron-nitrogen permanent magnet alloy powder by solid salt spray granulation and reduction diffusion method, which comprises steps: preparing and mixing raw materials; performing spray granulation; mixing microspheres obtained in the previous step with calcium particles, and performing a reduction diffusion reaction to obtain a samarium-iron alloy; and performing a nitriding treatment to obtain the product. The samarium-iron-nitrogen permanent magnet alloy powder obtained by spray granulation in this application has high coercivity, but the magnetic powder is difficult to be cleaned with water after the nitriding, which has a great impact on the subsequent granulation, and chloride is adopted in the spray granulation and easy to corrode equipment.
CN111403165A discloses a preparation method for a samarium-iron-nitrogen/nano-iron composite bonded permanent magnet. In this method, by using chemical vapor deposition method, a layer of nano-Fe film is coated on the surface of a samarium-iron-nitrogen powder for an oxidation resistant coating treatment, and the powder is subjected to granulation and then injection molding or calendering, mold-pressing and extrusion to prepare the composite bonded magnet. This bonded magnet has a high oxidation resistance but also a complicated preparation process, and the overall magnetic performance of the prepared bonded magnet is poor.
In view of shortcomings of the related art, it is urgent to provide a rare-earth permanent magnet material with excellent magnetic properties and a low cost.

SUMMARY

The following is a summary of the subject described in detail herein. This summary is not intended to limit the protection scope of the claims.
An example of the present application provides a samarium-based rare-earth permanent magnet material, a preparation method therefor and an application thereof. By the introduction of vanadium element, copper element and molybdenum element, an intrinsic property and a microstructure of the samarium-based rare-earth permanent magnet material can be adjusted, thereby improving the overall magnetic performance of the samarium-based rare-earth permanent magnet material, and the preparation process is simple and economical.
In a first aspect, an example of the present application provides a samarium-based rare-earth permanent magnet material, and the samarium-based rare-earth permanent magnet material has a composition in an atomic ratio: Sm₂Fe_αCu_βV_γMo_δN_ε, wherein 11.5 ≤ α ≤ 17.5, 0.1 ≤ β ≤ 0.4, 1.0 ≤ γ ≤ 1.8, 0 ≤ δ ≤ 1.0, and 2.9 ≤ ε ≤ 4.0.
In the composition Sm₂Fe_αCu_βV_γMo_δN_ε of the samarium-based rare-earth permanent magnet material, 11.5 ≤ α ≤ 17.5, which can be, for example, 11.5, 12.5, 13.5, 14.5, 15.5, 16.5 or 17.5; however, the α is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
In the composition Sm₂Fe_αCu_βV_γMo_δN_ε of the samarium-based rare-earth permanent magnet material, 0.1 ≤ β ≤ 0.4, which can be, for example, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 or 0.4; however, the β is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
In the composition Sm₂Fe_αCu_βV_γMo_δN_ε of the samarium-based rare-earth permanent magnet material, 1.0 ≤ γ ≤ 1.8, which can be, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or 1.8; however, the γ is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
In the composition Sm₂Fe_αCu_βV_γMo_δN_ε of the samarium-based rare-earth permanent magnet material, 0 ≤ δ ≤ 1.0, which can be, for example, 0, 0.2, 0.4, 0.6, 0.8 or 1.0; however, the δ is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
In the composition Sm₂Fe_αCu_βV_γMo_δN_ε of the samarium-based rare-earth permanent magnet material, 2.9 ≤ ε ≤ 4.0, which can be, for example, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9 or 4.0; however, the ε is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
For the samarium-based rare-earth permanent magnet material provided in the present application, the microstructure of the material such as grain boundaries, grain sizes or lattice defects are changed by doping the vanadium element, copper element and molybdenum element based on a samarium-iron-nitrogen rare-earth permanent magnet material, and by controlling an appropriate range of the atomic ratio, the samarium-based rare-earth permanent magnet material has excellent overall magnetic performance and oxidation resistance, which can meet the performance requirements of rare-earth permanent magnet materials.
In a second aspect, an example of the present application provides a preparation method for the samarium-based rare-earth permanent magnet material according to the first aspect, and the preparation method comprises the following steps:

(1) mixing a samarium powder, an iron powder, a copper powder, a vanadium powder and a molybdenum powder according to a formula amount, and performing melting and rapid-solidification ingot casting in sequence to obtain an alloy sheet;
(2) subjecting the alloy sheet obtained in step (1) to grinding, nitriding and ball-milling in sequence to obtain an alloy powder; and
(3) subjecting the alloy powder obtained in step (2) to phosphating and a heat treatment in sequence, and cooling to obtain the samarium-based rare-earth permanent magnet material.

In the preparation method for the samarium-based rare-earth permanent magnet material provided in the present application, by regulating parameters of the nitriding process, controlling a particle size of the ball-milling, and using the processes of phosphating and heat treatment at the same time, the oxidation resistant of the samarium-based rare-earth permanent magnet material can be effectively improved, and the remanence and coercivity are promoted to achieve a good balance, so that excellent overall magnetic performance can be obtained.
Preferably, the melting in step (1) is performed at a temperature of 1400-1600 °C, which can be, for example, 1400 °C, 1450 °C, 1500 °C, 1550 °C or 1600 °C; however, the temperature is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
Preferably, the melting in step (1) is performed for a period of 50-70 min, which can be, for example, 50 min, 55 min, 60 min, 65 min or 70 min; however, the period is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
Preferably, the melting in step (1) is performed in an argon atmosphere.
Preferably, the step of grinding in step (2) is: the alloy sheet obtained in step (1) is subjected to mechanical crushing and jet-mill grinding to obtain powder particles.
Preferably, an average particle size of the powder particles is 50-100 µm, which can be, for example, 50 µm, 60 µm, 70 µm, 80 µm, 90 µm or 100 µm; however, the average particle size is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
Preferably, the jet-mill grinding is performed in an argon atmosphere.
Preferably, the nitriding in step (2) comprises a first heat treatment and a second heat treatment which are performed in sequence.
Preferably, the first heat treatment is: under an ammonia atmosphere, a temperature is raised to 500-550 °C, and held for 4-10 h.
In the first heat treatment, the temperature is raised to 500-550 °C, which can be, for example, 500 °C, 510 °C, 520 °C, 530 °C, 540 °C or 550 °C; however, the temperature is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
In the first heat treatment, the temperature is held for a period of 4-10 h, which can be, for example, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h; however, the period is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
By the first heat treatment of the present application, the powder particles obtained by the grinding can be nitrided. In the composition Sm₂Fe_αCu_βV_γMo_δN_ε of the samarium-based rare-earth permanent magnet material, the value of ε is greatly affected by the heating temperature and the temperature holding period, and the value of ε is increased with the increase of the heating temperature and the temperature holding period. When the heating temperature and the temperature holding period are controlled within a reasonable range, the value of the ε can be kept within the range of 2.9-4.0, and the samarium-based rare-earth permanent magnet material has good magnetic properties.
Preferably, the second heat treatment is: under an argon atmosphere, a temperature is reduced to 400-450 °C, and held for 50-70 min.
In the second heat treatment, the temperature is reduced to 400-450 °C, which can be, for example, 400°C, 410 °C, 420 °C, 430 °C, 440 °C or 450 °C; however, the temperature is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
The second heat treatment has a temperature holding period of 50-70 min, which can be, for example, 50 min, 55 min, 60 min, 65 min or 70 min; however, the period is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
Preferably, the powder particles are subjected to the first heat treatment and the second heat treatment in sequence, and then cooled to room temperature under an argon atmosphere.
Preferably, the ball-milling in step (2) is performed in an argon atmosphere.
Preferably, an average particle size of the alloy powder in step (2) is 2-4 µm, which can be, for example, 2 µm, 2.5 µm, 3 µm, 3.5 µm or 4 µm; however, the average particle size is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
In the ball-milling of the present application, the average particle size of the alloy powder is controlled at 2-4 µm, and the prepared samarium-based rare-earth permanent magnet material has better overall magnetic performance. When the particle size is less than 2 µm, the coercivity of the material is increased, but the remanence is decreased greatly; when the particle size is more than 4 µm, the remanence of the material is increased slightly, but the coercivity is decreased significantly. Therefore, the particle size of the alloy powder is controlled within a reasonable range, which can promote remanence and coercivity to achieve a good balance, so that excellent overall magnetic performance is obtained.
Preferably, the step of phosphating in step (3) is: phosphoric acid, a solvent and the alloy powder obtained in step (2) are mixed and heated until the solvent is evaporated off to obtain a phosphated alloy powder.
An object of the phosphating treatment in the present application is to form a phosphating film on the surface of the alloy powder, improving the oxidation resistance of the alloy powder effectively.
Preferably, a mass of the phosphoric acid is 2.5-3.5wt% of a mass of the alloy powder in step (2), which can be, for example, 2.5wt%, 2.8wt%, 3.0wt%, 3.2wt% or 3.5wt%; however, the mass is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
Preferably, a mass ratio of the solvent to the alloy powder in step (2) is (0.8-1.2): 1, which can be, for example, 0.8: 1, 0.9: 1, 1: 1, 1.1: 1 or 1.2: 1; however, the mass ratio is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
Preferably, the solvent comprises ethanol.
Preferably, a final temperature of the heating is 78-82 °C, which can be, for example, 78 °C, 79 °C, 80 °C, 81 °C or 82 °C; however, the final temperature is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
Preferably, the phosphating in step (3) is performed in a nitrogen atmosphere.
Preferably, a final temperature of the heat treatment in step (3) is 140-160 °C, which can be, for example, 140 °C, 145 °C, 150 °C, 155 °C or 160 °C; however, the final temperature is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
Preferably, the heat treatment in step (3) has a temperature holding period of 3.5-4.5 h, which can be, for example, 3.5 h, 3.8 h, 4 h, 4.2 h or 4.5 h; however, the period is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
Preferably, the heat treatment in step (3) is performed in an oxygen-containing atmosphere, and a protective gas of the oxygen-containing atmosphere is nitrogen.
Preferably, in the oxygen-containing atmosphere, a concentration of the oxygen is 50-100 ppm, which can be, for example, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm or 100 ppm; however, the concentration is not limited to the listed values, and other unlisted values within this numerical range are also applicable.
By the heat treatment in the present application, the phosphating film formed on the surface of the phosphated alloy powder can be cured; in addition, by providing a trace amount of oxygen environment, a small area of the surface of the phosphated alloy powder which is not completely covered by the phosphating film is slightly oxidized to form a thin oxide film, further improving the oxidation resistant of the material.
As a preferred technical solution for the preparation method in the second aspect of the present application, the preparation method comprises the following steps:

(1) mixing a samarium powder, an iron powder, a copper powder, a vanadium powder and a molybdenum powder according to a formula amount, and in an argon atmosphere, sequentially performing melting at 1400-1600 °C for 50-70 min and rapid-solidification ingot casting to obtain an alloy sheet;
(2) sequentially subjecting the alloy sheet obtained in step (1) to mechanical crushing and jet-mill grinding, nitriding, and ball-milling in an argon atmosphere to obtain an alloy powder with an average particle size of 2-4 µm;
an average particle size of powder particles obtained by the jet-mill grinding is 50-100 µm; the nitriding comprises a first heat treatment and a second heat treatment which are performed in sequence; the first heat treatment is: under an ammonia atmosphere, the temperature is raised to 500-550 °C and kept for 4-10 h; the second heat treatment is: under an argon atmosphere, the temperature is reduced to 400-450 °C and kept for 50-70 min; and
(3) sequentially subjecting the alloy powder obtained in step (2) to phosphating, and a heat treatment which is performed to 140-160 °C with a temperature holding period of 3.5-4.5 h in an oxygen-containing atmosphere with an oxygen concentration of 50-100 ppm, and cooling to obtain the samarium-based rare-earth permanent magnet material;

In a third aspect, an example of the present application provides an application of the samarium-based rare-earth permanent magnet material according to the first aspect, and the samarium-based rare-earth permanent magnet material is used in the fields of small and special electrical machines, magnetic sensors or audio equipment.
Compared with the related art, the examples of the present application have the following beneficial effects.
For the samarium-based rare-earth permanent magnet material provided in examples of the present application, by doping the vanadium element, copper element and molybdenum element and controlling an appropriate range of the atomic ratio, the samarium-based rare-earth permanent magnet material accordingly has excellent overall magnetic performance, wherein the remanence is up to 7180 Gs, the coercivity is 10350 Oe, and the magnetic energy product is up to 12.3 MGOe.
By adopting the phosphating and heat treatment, the oxidation resistant of the material can be effectively improved. By adjusting the heating temperature and duration of the nitriding process, and controlling the particle size of the ball-milling, remanence and coercivity are promoted to achieve a good balance, so that excellent overall magnetic performance is obtained. The preparation method provided by the present application has a simple process and a low cost, which is suitable for the fields of small and special electrical machines, magnetic sensors or audio equipment.
After detailed descriptions are read and understood, other aspects can be understood.

DETAILED DESCRIPTION

The technical solutions of the present application will be further described below by embodiments. Those skilled in the art should understand that the examples merely assist in understanding the present application but should not be regarded as a specific limitation of the present application.

Example 1

This example provides a samarium-based rare-earth permanent magnet material, and the samarium-based rare-earth permanent magnet material has a composition in an atomic ratio: Sm₂Fe_αCu_βV_γMo_δN_ε, wherein α = 14, β = 0.3, γ = 1.5, δ = 0.5, and ε = 3.75.
The samarium-based rare-earth permanent magnet material is obtained by the preparation method below, and the preparation method comprises the following steps:

(1) a samarium powder, an iron powder, a copper powder, a vanadium powder and a molybdenum powder were mixed according to a formula amount, and in an argon atmosphere, sequentially subjected to melting at 1500 °C for 60 min and rapid-solidification ingot casting to obtain an alloy sheet;
(2) the alloy sheet obtained in step (1) was sequentially subjected to mechanical crushing and jet-mill grinding in the protection of argon, nitriding, and ball-milling in an argon atmosphere to obtain an alloy powder with an average particle size of 3 µm;
an average particle size of powder particles obtained by the jet-mill grinding was 80 µm; the nitriding comprised a first heat treatment and a second heat treatment which were performed in sequence; the first heat treatment was: under an ammonia atmosphere, the temperature was raised to 520 °C and kept for 7 h; the second heat treatment was: under an argon atmosphere, the temperature was reduced to 420 °C and kept for 60 min; and
(3) the alloy powder obtained in step (2) was sequentially subjected to phosphating, and a heat treatment which was performed to 150 °C with a temperature holding period of 4 h in an oxygen-containing atmosphere with an oxygen concentration of 70 ppm, and cooled to obtain the samarium-based rare-earth permanent magnet material;

Example 2

This example provides a samarium-based rare-earth permanent magnet material, and the samarium-based rare-earth permanent magnet material has a composition in an atomic ratio: Sm₂Fe_αCu_βV_γMo_δN_ε, wherein α = 14, β = 0.3, γ = 1.5, δ = 0.5, and ε = 3.70.
The samarium-based rare-earth permanent magnet material is obtained by the preparation method below, and the preparation method comprises the following steps:

(1) a samarium powder, an iron powder, a copper powder, a vanadium powder and a molybdenum powder were mixed according to a formula amount, and in an argon atmosphere, sequentially subjected to melting at 1450 °C for 65 min and rapid-solidification ingot casting to obtain an alloy sheet;
(2) the alloy sheet obtained in step (1) was sequentially subjected to mechanical crushing and jet-mill grinding in the protection of argon, nitriding, and ball-milling in an argon atmosphere to obtain an alloy powder with an average particle size of 3.5 µm;
an average particle size of powder particles obtained by the jet-mill grinding was 65 µm; the nitriding comprised a first heat treatment and a second heat treatment which were performed in sequence; the first heat treatment was: under an ammonia atmosphere, the temperature was raised to 510 °C and kept for 8.5 h; the second heat treatment was: under an argon atmosphere, the temperature was reduced to 410 °C and kept for 65 min; and
(3) the alloy powder obtained in step (2) was sequentially subjected to phosphating, a heat treatment which was performed to 145 °C with a temperature holding period of 4.2 h in an oxygen-containing atmosphere with an oxygen concentration of 60 ppm, and cooled to obtain the samarium-based rare-earth permanent magnet material;

Example 3

This example provides a samarium-based rare-earth permanent magnet material, and the samarium-based rare-earth permanent magnet material has a composition in an atomic ratio: Sm₂Fe_αCu_βV_γMo_δN_ε, wherein α = 14, β = 0.3, γ = 1.5, δ = 0.5, and ε = 3.80.
The samarium-based rare-earth permanent magnet material is obtained by the preparation method below, and the preparation method comprises the following steps:

(1) a samarium powder, an iron powder, a copper powder, a vanadium powder and a molybdenum powder were mixed according to a formula amount, and in an argon atmosphere, sequentially subjected to melting at 1550 °C for 55 min and rapid-solidification ingot casting to obtain an alloy sheet;
(2) the alloy sheet obtained in step (1) was sequentially subjected to mechanical crushing and jet-mill grinding in the protection of argon, nitriding, and ball-milling in an argon atmosphere to obtain an alloy powder with an average particle size of 2.5 µm;
an average particle size of powder particles obtained by the jet-mill grinding was 90 µm; the nitriding comprised a first heat treatment and a second heat treatment which were performed in sequence; the first heat treatment was: under an ammonia atmosphere, the temperature was raised to 535 °C and kept for 5.5 h; the second heat treatment was: under an argon atmosphere, the temperature was reduced to 435 °C and kept for 55 min; and
(3) the alloy powder obtained in step (2) was sequentially subjected to phosphating, a heat treatment which was performed to 155 °C with a temperature holding period of 3.8 h in an oxygen-containing atmosphere with an oxygen concentration of 85 ppm, and cooled to obtain the samarium-based rare-earth permanent magnet material;

Example 4

This example provides a samarium-based rare-earth permanent magnet material, and the samarium-based rare-earth permanent magnet material has a composition in an atomic ratio: Sm₂Fe_αCu_βV_γMo_δN_ε, wherein α = 14, β = 0.3, γ = 1.5, δ = 0.5, and ε = 3.62.
The samarium-based rare-earth permanent magnet material is obtained by the preparation method below, and the preparation method comprises the following steps:

(1) a samarium powder, an iron powder, a copper powder, a vanadium powder and a molybdenum powder were mixed according to a formula amount, and in an argon atmosphere, sequentially subjected to melting at 1400 °C for 70 min and rapid-solidification ingot casting to obtain an alloy sheet;
(2) the alloy sheet obtained in step (1) was sequentially subjected to mechanical crushing and jet-mill grinding in the protection of argon, nitriding, and ball-milling in an argon atmosphere to obtain an alloy powder with an average particle size of 2 µm;
an average particle size of powder particles obtained by the jet-mill grinding was 50 µm; the nitriding comprised a first heat treatment and a second heat treatment which were performed in sequence; the first heat treatment was: under an ammonia atmosphere, the temperature was raised to 500 °C and kept for 10 h; the second heat treatment was: under an argon atmosphere, the temperature was reduced to 400 °C and kept for 70 min; and
(3) the alloy powder obtained in step (2) was sequentially subjected to phosphating, a heat treatment which was performed to 140 °C with a temperature holding period of 4.5 h in an oxygen-containing atmosphere with an oxygen concentration of 50 ppm, and cooled to obtain the samarium-based rare-earth permanent magnet material;

Example 5

This example provides a samarium-based rare-earth permanent magnet material, and the samarium-based rare-earth permanent magnet material has a composition in an atomic ratio: Sm₂Fe_αCu_βV_γMo_δN_ε, wherein α = 14, β = 0.3, γ = 1.5, δ = 0.5, and ε = 3.21.
The samarium-based rare-earth permanent magnet material is obtained by adopting a preparation method below, and the preparation method comprises the following steps:

(1) a samarium powder, an iron powder, a copper powder, a vanadium powder and a molybdenum powder were mixed according to a formula amount, and in an argon atmosphere, sequentially subjected to melting at 1600 °C for 50 min and rapid-solidification ingot casting to obtain an alloy sheet;
(2) the alloy sheet obtained in step (1) was subjected to mechanical crushing and jet-mill grinding in the protection of argon, nitriding, and ball-milling in an argon atmosphere in sequence to obtain an alloy powder with an average particle size of 4 µm;
an average particle size of powder particles obtained by the jet-mill grinding was 100 µm; the nitriding comprised a first heat treatment and a second heat treatment which were performed in sequence; the first heat treatment was: under an ammonia atmosphere, the temperature was raised to 550 °C and kept for 4 h; the second heat treatment was: under an argon atmosphere, the temperature was reduced to 450 °C and kept for 50 min;
(3) the alloy powder obtained in step (2) was sequentially subjected to phosphating, a heat treatment which was performed to 160 °C with a temperature holding period of 3.5 h in an oxygen-containing atmosphere with an oxygen concentration of 100 ppm, and cooled to obtain the samarium-based rare-earth permanent magnet material;

Example 6

This example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that the samarium-based rare-earth permanent magnet material has a composition in an atomic ratio: Sm₂Fe_αCu_βV_γN_ε, wherein α = 11.5, β = 0.1, γ = 1.0, and ε = 4.20. The rest is the same as in Example 1.

Example 7

This example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that the samarium-based rare-earth permanent magnet material has a composition in an atomic ratio: Sm₂Fe_αCu_βV_γMo_δN_ε, wherein α = 17.5, β = 0.4, γ = 1.8, δ = 1.0, and ε = 2.90. The rest is the same as in Example 1.

Example 8

This example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that for the samarium-based rare-earth permanent magnetic material, ε is 2.68, and in the preparation method for the samarium-based rare-earth permanent magnet material, the stages of heating and temperature holding are: under an ammonia atmosphere, the temperature is raised to 480 °C, and kept for 7 h. The rest is the same as in Example 1.

Example 9

This example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that for the samarium-based rare-earth permanent magnetic material, ε is 2.65, and in the preparation method for the samarium-based rare-earth permanent magnet material, the stages of heating and temperature holding are: under an ammonia atmosphere, the temperature is raised to 570 °C, and kept for 7 h. The rest is the same as in Example 1.

Example 10

This example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that for the samarium-based rare-earth permanent magnetic material, ε is 2.85, and in the preparation method for the samarium-based rare-earth permanent magnet material, the stages of heating and temperature holding are: under an ammonia atmosphere, the temperature is raised to 520 °C, and kept for 2 h. The rest is the same as in Example 1.

Example 11

This example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that for the samarium-based rare-earth permanent magnetic material, ε is 2.67, and in the preparation method for the samarium-based rare-earth permanent magnet material, the stages of heating and temperature holding are: under an ammonia atmosphere, the temperature is raised to 520 °C, and kept for 12 h. The rest is the same as in Example 1.

Example 12

This example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that for the samarium-based rare-earth permanent magnetic material, ε is 3.75, and in the preparation method for the samarium-based rare-earth permanent magnet material, an average particle size of the alloy powder is adjusted to 1 µm. The rest is the same as in Example 1.

Example 13

This example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that for the samarium-based rare-earth permanent magnetic material, ε is 3.75, and in the preparation method for the samarium-based rare-earth permanent magnet material, an average particle size of the alloy powder is adjusted to 5 µm. The rest is the same as in Example 1.

Example 14

This example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that for the samarium-based rare-earth permanent magnetic material, ε is 3.75, and in the preparation method for the samarium-based rare-earth permanent magnet material, an oxygen concentration of the mixed atmosphere is adjusted to 30 ppm. The rest is the same as in Example 1.

Example 15

This example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that for the samarium-based rare-earth permanent magnetic material, ε is 3.75, and in the preparation method for the samarium-based rare-earth permanent magnet material, an oxygen concentration of the mixed atmosphere is adjusted to 120 ppm. The rest is the same as in Example 1.

Comparative Example 1

This comparative example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that the samarium-based rare-earth permanent magnet material has a composition in an atomic ratio: Sm₂Fe_αCu_βAl_γN_ε, wherein α = 15, β = 0.3, γ = 2, and ε = 3.57. The rest is the same as in Example 1.

Comparative Example 2

This comparative example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that the samarium-based rare-earth permanent magnet material has a composition in an atomic ratio: Sm_1.8Nd_0.2Fe_αCo_βV_γCr_δN_ε, wherein α = 15, β = 0.5, γ = 1.5, δ = 0.5, and ε = 3.32. The rest is the same as in Example 1.

Comparative Example 3

This comparative example provides a samarium-based rare-earth permanent magnet material, which differs from Example 1 in that for the samarium-based rare-earth permanent magnetic material, ε is 3.65, and in the preparation method for the samarium-based rare-earth permanent magnet material, step (3) is not performed. The rest is the same as in Example 1.

The samarium-based rare-earth permanent magnet material provided by Examples 1-15 and Comparative Examples 1-3 is mixed with an epoxy resin binder according to a mass ratio of 9: 1, and then pressed into a cylinder of Φ10×10 m under a magnetic field of 1.5 T, and the magnetic performance test is performed with a B-H tester, and the obtained results are shown in Table 1.

Table 1

	Remanence (Gs)	Coercivity (Oe)	Magnetic energy product (MGOe)
Example 1	7180	10350	12.3
Example 2	7100	9950	11.8
Example 3	7130	10060	12.0
Example 4	7050	9980	11.7
Example 5	6750	9760	8.9
Example 6	6670	13010	8.7
Example 7	7150	10100	12.1
Example 8	4150	4460	3.1
Example 9	4190	4540	3.3
Example 10	5100	6400	5.0
Example 11	3940	2920	2.92
Example 12	6700	14200	8.5
Example 13	5730	2130	4.7
Example 14	6870	8730	10.5
Example 15	7030	7640	11.1
Comparative Example 1	6320	6770	8.5
Comparative Example 2	6130	6250	7.9
Comparative Example 3	6750	6320	9.5

It can be seen from Table 1 that for the samarium-based rare-earth permanent magnet material provided by the present application, the remanence and coercivity can achieve a good balance, and the magnet contains a large amount of energy, and has excellent overall magnetic performance, which can meet the performance requirements of permanent magnet materials.
It can be seen from the comparison of Example 1 and Examples 2-5 that by controlling the preparation process parameters such as the particle size of the ball-milling, the heating temperature and the temperature holing periodtemperature holding period within reasonable ranges, the remanence and coercivity both can be guaranteed to reach a good state.
It can be seen from the comparison of Example 1 with Example 6 and Example 7 that by introducing the copper element, vanadium element and molybdenum element with a suitable atomic ratio, the samarium-based rare-earth permanent magnet material is endowed with good magnetic properties; it can be seen from the comparison of Example 1 and Examples 8-11 that the heating temperature and the temperature holding period have a great impact on the nitrogen content, when the heating temperature is too high or too low, or the temperature holding period is too long or too short, the samarium-based rare-earth permanent magnet material cannot have an appropriate nitrogen content, so that it is difficult to ensure the magnetic properties of the material; it can be seen from the comparison of Example 1 with Example 12 and Example 13 that if the particle size of ball-milling is too small, the coercivity of the magnetic powder is increased, but the remanence is decreased greatly, and if the particle size of ball-milling is too large, the remanence of the magnetic powder is increased slightly, but the coercivity is decreased significantly; it can be seen from the comparison of Example 1 with Example 14 and Example 15 that in the heat treatment process, the oxygen concentration of the mixed atmosphere has a certain impact on the oxidation resistant of the samarium-based rare-earth permanent magnet material, and the overly high or overly low oxygen concentration is not conducive to the slight oxidation of the surface of the magnetic powder particles, thereby worsening the magnetic properties of the material.
It can be seen from the comparison of Example 1 with Comparative Example 1 and Comparative Example 2 that the material using other doped elements has changed microstructure, and its overall magnetic performance is lower than the overall magnetic performance of the samarium-based rare-earth permanent magnet material provided in the present application; it can be seen from the comparison of Example 1 and Comparative Example 3 that the alloy powder without phosphating and heat treatment has poor oxidation resistance, which further deteriorates the overall magnetic performance of the material.
In summary, by doping the vanadium element, copper element and molybdenum element and controlling the atomic ratio within an appropriate range, the samarium-based rare-earth permanent magnet material provided by the present application is endowed with excellent overall magnetic performance, wherein the remanence is up to 7180 Gs, the coercivity is 10350 Oe, and the magnetic energy product is up to 12.3 MGOe.
By adopting the phosphating and heat treatment, the oxidation resistant of the samarium-based rare-earth permanent magnet material can be effectively improved. By adjusting the heating temperature and duration of the nitriding process, and controlling the particle size of the ball-milling, remanence and coercivity are promoted to achieve a good balance, so that excellent overall magnetic performance is obtained. The preparation method provided by the present application has a simple process and a low cost, which is suitable for the fields of small and special electrical machines, magnetic sensors or audio equipment.
The above is only embodiments of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any change or replacement that can be easily thought of within the technical scope disclosed by the present application shall fall within the protection scope and disclosure scope of the present application.

Claims

A samarium-based rare-earth permanent magnet material, which has a composition in an atomic ratio: Sm₂Fe_αCu_βV_γMo_δN_ε, wherein 11.5 ≤ α ≤ 17.5, 0.1 ≤ β ≤ 0.4, 1.0 ≤ γ ≤ 1.8, 0 ≤ δ ≤ 1.0, and 2.9 ≤ ε ≤ 4.0.
A preparation method for the samarium-based rare-earth permanent magnet material according to claim 1, comprising the following steps:
(1) mixing a samarium powder, an iron powder, a copper powder, a vanadium powder and a molybdenum powder according to a formula amount, and performing melting and rapid-solidification ingot casting in sequence to obtain an alloy sheet;

(2) subjecting the alloy sheet obtained in step (1) to grinding, nitriding and ball-milling in sequence to obtain an alloy powder; and

(3) subjecting the alloy powder obtained in step (2) to phosphating and a heat treatment in sequence, and cooling to obtain the samarium-based rare-earth permanent magnet material.
The preparation method according to claim 2, wherein the melting in step (1) is performed at a temperature of 1400-1600 °C.
The preparation method according to claim 2 or 3, wherein the melting in step (1) is performed for a period of 50-70 min.
The preparation method according to any one of claims 2-4, wherein the melting in step (1) is performed in an argon atmosphere.
The preparation method according to any one of claims 2-5, wherein the step of grinding in step (2) is: subjecting the alloy sheet obtained in step (1) to mechanical crushing and jet-mill grinding in sequence to obtain powder particles;
preferably, an average particle size of the powder particles is 50-100 µm;

preferably, the jet-mill grinding is performed in an argon atmosphere.
The preparation method according to any one of claims 2-6, wherein the nitriding in step (2) comprises a first heat treatment and a second heat treatment which are performed in sequence;
preferably, the first heat treatment is: under an ammonia atmosphere, heating to 500-550 °C, and holding the temperature for 4-10 h;

preferably, the second heat treatment is: under an argon atmosphere, cooling to 400-450 °C, and holding the temperature for 50-70 min.
The preparation method according to any one of claims 2-7, wherein the ball-milling in step (2) is performed in an argon atmosphere;
preferably, an average particle size of the alloy powder in step (2) is 2-4 µm.
The preparation method according to any one of claims 2-8, wherein the step of phosphating in step (3) is: mixing phosphoric acid, a solvent and the alloy powder obtained in step (2), and heating until the solvent is evaporated off to obtain a phosphated alloy powder;
preferably, a mass of the phosphoric acid is 2.5-3.5wt% of a mass of the alloy powder in step (2);

preferably, a mass ratio of the solvent to the alloy powder in step (2) is (0.8-1.2): 1;

preferably, the solvent comprises ethanol;

preferably, the heating is performed to a final temperature of 78-82 °C;

preferably, the phosphating in step (3) is performed in a nitrogen atmosphere.
The preparation method according to any one of claims 2-9, wherein a final temperature of the heat treatment in step (3) is 140-160 °C;
preferably, the heat treatment in step (3) has a temperature holding period of 3.5-4.5 h;

preferably, the heat treatment in step (3) is performed in an oxygen-containing atmosphere, and a protective gas of the oxygen-containing atmosphere is nitrogen;

preferably, the oxygen-containing atmosphere has an oxygen concentration of 50-100 ppm.
The preparation method according to any one of claims 2-10, comprising the following steps:
(1) mixing a samarium powder, an iron powder, a copper powder, a vanadium powder and a molybdenum powder according to a formula amount, and in an argon atmosphere, sequentially performing melting at 1400-1600 °C for 50-70 min and rapid-solidification ingot casting to obtain an alloy sheet;

(2) sequentially subjecting the alloy sheet obtained in step (1) to mechanical crushing and jet-mill grinding, nitriding, and ball-milling in an argon atmosphere to obtain an alloy powder with an average particle size of 2-4 µm;
an average particle size of powder particles obtained by the jet-mill grinding is 50-100 µm; the nitriding comprises a first heat treatment and a second heat treatment which are performed in sequence; the first heat treatment is: under an ammonia atmosphere, heating to 500-550 °C and holding the temperature for 4-10 h; the second heat treatment is: under an argon atmosphere, cooling to 400-450 °C and holding the temperature for 50-70 min; and

(3) sequentially subjecting the alloy powder obtained in step (2) to phosphating, and a heat treatment which is performed to 140-160 °C with a temperature holding period of 3.5-4.5 h in an oxygen-containing atmosphere with an oxygen concentration of 50-100 ppm, and cooling to obtain the samarium-based rare-earth permanent magnet material;
the step of phosphating is: in a nitrogen atmosphere, mixing phosphoric acid, a solvent and the alloy powder obtained in step (2), and heating until the solvent is evaporated off to obtain a phosphated alloy powder; a mass of the phosphoric acid is 2.5-3.5wt% of a mass of the alloy powder in step (2); a mass ratio of the solvent to the alloy powder in step (2) is (0.8-1.2): 1.
An application of the samarium-based rare-earth permanent magnet material according to claim 1, wherein the samarium-based rare-earth permanent magnet material is used in the fields of small and special electrical machines, magnetic sensors or audio equipment.