A rare earth permanent magnet material with high temperature stability and a preparation method thereof
By optimizing the preparation process of Sm2Co17 permanent magnet material through spark plasma sintering and heat treatment, a cellular structure was formed, which solved the problems of large grain size and insufficient temperature stability, achieving high temperature stability and excellent corrosion resistance, and simplifying the production process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JIANGXI UNIV OF SCI & TECH
- Filing Date
- 2021-09-07
- Publication Date
- 2026-05-29
AI Technical Summary
The existing preparation process of Sm2Co17 permanent magnet materials results in large grains, poor corrosion resistance and mechanical properties, long production cycle and difficulty in controlling product consistency, and insufficient temperature stability. Traditional addition of heavy rare earth elements such as Dy, Gd or Zr has limited effect.
SmxCo100-xy-zHfyMz powder was prepared by spark plasma sintering and combined with heat treatment to form a cellular structure. M is one or more of Zr, Fe, and Cu elements. The grain size and element distribution were optimized by spark plasma sintering and heat treatment.
Rare earth permanent magnet materials with fine grains and high temperature stability were prepared, with a coercivity temperature coefficient in the range of -0.14 to -0.17%/K, which broadened the operating temperature range, improved corrosion resistance and mechanical properties, and simplified the preparation process.
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Figure CN113903538B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of rare earth permanent magnet materials, and specifically provides a rare earth permanent magnet material with high temperature stability and its preparation method. Background Technology
[0002] Sm2Co 17 As a second-generation rare-earth permanent magnet material, rare-earth permanent magnet alloys possess high saturation magnetization, high uniaxial anisotropy, and high Curie temperature. Due to their excellent high-temperature magnetic properties and good oxidation and corrosion resistance, they have unparalleled advantages over third-generation Nd-Fe-B rare-earth permanent magnet materials and are widely used in aerospace, defense, sensors, microwave devices, magnetic pumps, high-end motors, and other fields.
[0003] Currently, Sm2Co 17 The preparation process of permanent magnet materials mainly adopts the traditional powder metallurgy method. The main steps include: composition design, melting, powder preparation, orientation molding, isostatic pressing, sintering, and heat treatment. Magnets prepared using this method have relatively large grain sizes. In the powder preparation stage, the alloy needs to be coarsely and finely crushed using ball milling to achieve a powder particle size of 3-5 μm. After sintering, the grain size will grow to 10-30 μm. Traditionally sintered Sm2Co... 17 Magnets have poor corrosion resistance and mechanical properties due to their large grain size, and the complicated manufacturing process leads to long production cycles and difficulty in controlling product consistency.
[0004] In addition, temperature stability can affect Sm2Co 17 In order to improve the temperature stability of permanent magnet materials, heavy rare earth elements such as Dy and Gd are usually added for temperature compensation, or Zr is added. However, heavy rare earth elements are expensive, and simply adding Zr has a relatively weak effect on improving temperature stability. Summary of the Invention
[0005] To address the aforementioned technical problems, the present invention aims to provide a rare-earth permanent magnet material with high temperature stability and a preparation method thereof. This method can improve the temperature stability of rare-earth permanent magnets, thereby broadening the operating temperature range of the magnets.
[0006] The technical solution of this invention is as follows:
[0007] A rare-earth permanent magnet material with high temperature stability, characterized in that: the composition and content of the rare-earth permanent magnet material are expressed by the formula: Sm x Co 100-x-y-z Hf y M zWhere M is one or more of Zr, Fe, and Cu, and x, y, and z represent mass percentages, 24 <x<27,0<y≤2,0<z<30。
[0008] The method for preparing rare-earth permanent magnet materials with high temperature stability according to the present invention is characterized by the following specific steps:
[0009] ① Spark plasma sintering: Sm... x Co 100-x-y-z Hf y M z Powder is poured into a graphite mold and formed into a bulk material using spark plasma sintering technology. The sintering temperature is 800-1000℃, the sintering pressure is 20-80MPa, the sintering time is 0.5-20min, and the vacuum degree is less than 10Pa before spark plasma sintering and throughout the sintering process.
[0010] ② Heat treatment: The obtained bulk material is encapsulated in a quartz tube for solution and aging heat treatment. The solution temperature is 1050-1150℃ and the solution time is 0.5-8h. Then, it is water-quenched to room temperature, and then the bulk material is aged at 800-950℃ for 5-25h. Then, it is cooled to 400℃ at a cooling rate of 0.5-1℃ / min, and finally water-quenched to room temperature.
[0011] In step ①, the Sm x Co 100-x-y-z Hf y M z The powder preparation method is as follows: Elements Sm, Co, Hf, and M are mixed according to Sm... x Co 100-x-y-z Hf y M z The raw materials are proportioned and placed in an electric arc furnace for melting under an argon atmosphere to obtain a master alloy ingot. The oxide layer of the alloy ingot is removed, and the rapidly quenched alloy strip is prepared at a speed of 40 m / s by rapid melt quenching. The alloy strip is then crushed into powder under atmosphere protection.
[0012] In step ①, a dense bulk rare earth permanent magnet material is prepared by spark plasma sintering technology. The internal grain size of the magnet is 0.5-2μm, and there is a typical twin structure inside. The twin structure size is between 5-8nm, and the Hf element is mainly distributed in the grain boundary phase.
[0013] In step ②, the magnet obtained after heat treatment has a fine internal grain size of only 1-4 μm, exhibiting a typical cellular structure with an average size of 78-85 nm. This structure forms a 1:5H cell wall phase with a thickness of 8-10 nm, and the density of the lamellar phase is approximately 0.025-0.03 nm.-1 The elements inside the magnet are evenly distributed.
[0014] As a preferred technical solution:
[0015] In step ①, the sintering temperature is 950℃, the sintering pressure is 50MPa, and the sintering time is 5min;
[0016] In step ②, the solution temperature is 1100℃ and the solution time is 4h; the aging temperature is 800℃ and the aging time is 10h, then the temperature is cooled to 400℃ at a cooling rate of 1℃ / min, and finally the temperature is quenched in water to room temperature.
[0017] By adopting the above preferred scheme, the coercivity temperature coefficient of the material can be further optimized.
[0018] The rare earth permanent magnet material prepared by the method described in this invention has a small grain size and excellent coercivity temperature stability. In the temperature range of 300K-673K, its coercivity temperature coefficient is -0.14 to -0.17% / K.
[0019] The beneficial effects of this invention are as follows:
[0020] 1) The rare earth permanent magnet material of the present invention has small grain size and high temperature stability.
[0021] 2) The preparation process described in this invention is simple and efficient, without the need for cumbersome processes such as ball milling of powder, and the resulting products have high consistency.
[0022] 3) The rare earth permanent magnet material prepared by the method described in this invention has a small internal grain size, exhibits a typical cellular structure, and has a uniform distribution of elements inside the material, which further improves the corrosion resistance and mechanical properties of the magnet.
[0023] 4) The method described in this invention effectively improves the coercivity temperature stability of the material. Within the temperature range of 300K-673K, the coercivity temperature coefficient of the material is -0.14 to -0.17% / K, which is comparable to other Sm2Co materials. 17 Compared to permanent magnet alloys, the present invention broadens the operating temperature range of the magnet material. Attached Figure Description
[0024] Figure 1 This is a transmission electron microscope (TEM) image of the discharge plasma sintered magnet from Example 1. Detailed Implementation
[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, the present invention is not limited to these embodiments. The following embodiments are for illustrative purposes only and should not be used to limit the scope of the present invention and the claims.
[0026] Example 1
[0027] The elements Sm, Co, Fe, Cu, Zr, and Hf are arranged according to Sm 24.6 Co 50 Fe 17.4 Cu 5.7 Zr 1.3 Hf 1.0 The raw materials are proportioned and placed in an electric arc melting furnace for melting under an argon atmosphere to obtain a master alloy ingot. The ingot is then processed into a fast-quenched alloy strip using a strip spinning machine with a roller speed of 40 m / s. The alloy strip is then crushed into powder under argon protection.
[0028] The powder was poured into a graphite mold and rapidly sintered using a spark plasma sintering (SPCS) machine to produce the magnet. The vacuum level before and throughout the sintering process was less than 10 Pa, the sintering temperature was 950℃, the sintering pressure was 50 MPa, and the sintering time was 5 min. After sintering, the magnet was solution-treated at 1100℃ for 4 h, then water-quenched to room temperature, aged at 800℃ for 10 h, cooled to 400℃ at a rate of 1℃ / min, and finally water-quenched to room temperature.
[0029] After heat treatment, the internal grain size of the magnet is 1.2-3.3 μm, exhibiting a typical cellular structure with an average cell size of 78-85 nm. A 1:5H cell wall phase is formed, with a thickness of 8-10 nm, and the density of the lamellar phase is approximately 0.027 nm. -1 The elements inside the magnet are evenly distributed; the temperature coefficient of coercivity is -0.17% / K in the temperature range of 300K-673K.
[0030] Comparative Example 1
[0031] The elements Sm, Co, Fe, Cu, and Zr are arranged according to Sm 24.6 Co 50 Fe 17.4 Cu 5.7 Zr 2.3 The raw materials are proportioned and placed in an electric arc melting furnace for melting under an argon atmosphere to obtain a master alloy ingot. The ingot is then processed into a fast-quenched alloy strip using a strip spinning machine with a roller speed of 40 m / s. The alloy strip is then crushed into powder under argon protection.
[0032] Powder was poured into a graphite mold and rapidly sintered using a spark plasma sintering (SPCS) machine to produce the magnet. The vacuum level before and throughout the sintering process was less than 10 Pa, the sintering temperature was 950℃, the sintering pressure was 50 MPa, and the sintering time was 5 min. After sintering, the magnet was solution-treated at 1100℃ for 4 h, then water-quenched to room temperature, then aged at 800℃ for 5 h, then cooled to 400℃ at a rate of 1℃ / min, and finally water-quenched to room temperature.
[0033] After heat treatment, the internal grain size of the magnet is relatively large, ranging from 4 to 10 μm, and the coercivity temperature coefficient is -0.19% / K in the temperature range of 300K-673K.
[0034] Comparative Example 2
[0035] The elements Sm, Co, Fe, Cu, Zr, and Hf are arranged according to Sm 24.6 Co 50 Fe 17.4 Cu 5.7 Zr 1.3 Hf 1.0 The raw materials are proportioned and placed in an electric arc melting furnace for melting under an argon atmosphere to obtain a master alloy ingot. The ingot is then processed into a fast-quenched alloy strip using a strip spinning machine with a roller speed of 40 m / s. The alloy strip is then crushed into powder under argon protection.
[0036] Powder was poured into a graphite mold and rapidly sintered using a spark plasma sintering (SPCS) system to produce the magnet. The vacuum level before and throughout the sintering process was less than 10 Pa, the sintering temperature was 800℃, the sintering pressure was 40 MPa, and the sintering time was 5 min. After sintering, the magnet was solution-treated at 1050℃ for 0.1 h, then water-quenched to room temperature, and subsequently aged at 800℃ for 10 h. It was then cooled to 400℃ at a rate of 1℃ / min and finally water-quenched to room temperature.
[0037] After heat treatment, the magnet has a coercivity temperature coefficient of -0.21% / K in the temperature range of 300K-673K.
[0038] Comparative Example 3
[0039] The elements Sm, Co, Fe, Cu, Zr, and Hf are arranged according to Sm 24.6 Co 50 Fe 17.4 Cu 5.7 Zr 1.3 Hf 1.0 The raw materials are proportioned and placed in an electric arc melting furnace for melting under an argon atmosphere to obtain a master alloy ingot. The ingot is then processed into a fast-quenched alloy strip using a strip spinning machine with a roller speed of 40 m / s. The alloy strip is then crushed into powder under argon protection.
[0040] Powder was poured into a graphite mold and rapidly sintered using a spark plasma sintering (SPCS) system to produce the magnet. The vacuum level before and throughout the sintering process was less than 10 Pa, the sintering temperature was 1000℃, the sintering pressure was 50 MPa, and the sintering time was 5 min. After sintering, the magnet was solution-treated at 1100℃ for 0.3 h, then water-quenched to room temperature, aged at 800℃ for 20 h, cooled to 400℃ at a rate of 1.5℃ / min, and finally water-quenched to room temperature.
[0041] After heat treatment, the magnet has a coercivity temperature coefficient of -0.20% / K in the temperature range of 300K-673K.
[0042] Comparative Example 4
[0043] The elements Sm, Co, Fe, Cu, Zr, and Hf are arranged according to Sm 24.6 Co 50 Fe 17.4 Cu 5.7 Zr 1.3 Hf 1.0 The raw materials are proportioned and placed in an electric arc melting furnace for melting under an argon atmosphere to obtain a master alloy ingot. The ingot is then processed into a fast-quenched alloy strip using a strip spinning machine with a roller speed of 40 m / s. The alloy strip is then crushed into powder under argon protection.
[0044] Powder was poured into a graphite mold and rapidly sintered using a spark plasma sintering (SPCS) system to produce the magnet. The vacuum level before and throughout the sintering process was less than 10 Pa, the sintering temperature was 850℃, the sintering pressure was 90 MPa, and the sintering time was 25 min. After sintering, the magnet was solution-treated at 1100℃ for 10 h, then water-quenched to room temperature, and subsequently aged at 1000℃ for 30 h. It was then cooled to 400℃ at a rate of 1.2℃ / min and finally water-quenched to room temperature.
[0045] After heat treatment, the magnet has a coercivity temperature coefficient of -0.19% / K in the temperature range of 300K-673K.
[0046] Comparative Example 5
[0047] The elements Sm, Co, Fe, Cu, Zr, and Hf are arranged according to Sm 24.6 Co 50 Fe 17.4 Cu 5.7 Zr 1.8 Hf 0.5 The raw materials are proportioned and placed in an electric arc melting furnace for melting under an argon atmosphere to obtain a master alloy ingot. The ingot is then processed into a fast-quenched alloy strip using a strip spinning machine with a roller speed of 40 m / s. The alloy strip is then crushed into powder under argon protection.
[0048] Powder was poured into a graphite mold and rapidly sintered using a spark plasma sintering (SPCS) machine to produce the magnet. The vacuum level before and throughout the sintering process was less than 10 Pa, the sintering temperature was 1080℃, the sintering pressure was 30 MPa, and the sintering time was 2 min. After sintering, the magnet was solution-treated at 1180℃ for 10 h, then water-quenched to room temperature, then aged at 750℃ for 5 h, then cooled to 400℃ at a rate of 3℃ / min, and finally water-quenched to room temperature.
[0049] After heat treatment, the magnet has a coercivity temperature coefficient of -0.23% / K in the temperature range of 300K-673K.
[0050] Example 2
[0051] The elements Sm, Co, Fe, Cu, Zr, and Hf are arranged according to Sm 24.6 Co 50 Fe 17.4 Cu 5.7 Zr 0.3 Hf 2.0 The raw materials are proportioned and placed in an electric arc melting furnace for melting under an argon atmosphere to obtain a master alloy ingot. The ingot is then processed into a fast-quenched alloy strip using a strip spinning machine with a roller speed of 40 m / s. The alloy strip is then crushed into powder under argon protection.
[0052] Powder was poured into a graphite mold and rapidly sintered using a spark plasma sintering (SPCS) machine to produce the magnet. The vacuum level before and throughout the sintering process was less than 10 Pa, the sintering temperature was 900℃, the sintering pressure was 80 MPa, and the sintering time was 10 min. After sintering, the magnet was solution-treated at 1100℃ for 4 hours, then water-quenched to room temperature, and then aged at 800℃ for 5 hours. It was then cooled to 400℃ at a rate of 1℃ / min, and finally water-quenched to room temperature.
[0053] After heat treatment, the internal grain size of the magnet is 1.4-3.2μm, and the coercivity temperature coefficient is -0.15% / K in the temperature range of 300K-673K.
[0054] Example 3
[0055] The elements Sm, Co, Fe, Cu, Zr, and Hf are arranged according to Sm 25 Co 50 Fe 15 Cu6Zr 3.5 Hf 0.5 The raw materials are proportioned and placed in an electric arc melting furnace for melting under an argon atmosphere to obtain a master alloy ingot. The ingot is then processed into a fast-quenched alloy strip using a strip spinning machine with a roller speed of 40 m / s. The alloy strip is then crushed into powder under argon protection.
[0056] Powder was poured into a graphite mold and rapidly sintered using a spark plasma sintering (SPCS) machine to produce the magnet. The vacuum level before and throughout the sintering process was less than 10 Pa, the sintering temperature was 900℃, the sintering pressure was 80 MPa, and the sintering time was 10 min. After sintering, the magnet was solution-treated at 1050℃ for 8 hours, then water-quenched to room temperature, and subsequently aged at 850℃ for 10 hours. It was then cooled to 400℃ at a rate of 1℃ / min, and finally water-quenched to room temperature.
[0057] After heat treatment, the internal grain size of the magnet is 1.7-3.7μm, and the coercivity temperature coefficient is -0.17% / K in the temperature range of 300K-673K.
[0058] Example 4
[0059] The elements Sm, Co, Fe, Cu, Zr, and Hf are arranged according to Sm 25.5 Co 57 Fe 9.5 Cu 4.7 Zr 2.3 Hf 1.0 The raw materials are proportioned and placed in an electric arc melting furnace for melting under an argon atmosphere to obtain a master alloy ingot. The ingot is then processed into a fast-quenched alloy strip using a strip spinning machine with a roller speed of 40 m / s. The alloy strip is then crushed into powder under argon protection.
[0060] Powder was poured into a graphite mold and rapidly sintered using a spark plasma sintering (SPCS) system to produce the magnet. The vacuum level before and throughout the sintering process was less than 10 Pa, the sintering temperature was 960℃, the sintering pressure was 45 MPa, and the sintering time was 4 min. After sintering, the magnet was solution-treated at 1050℃ for 6 h, then water-quenched to room temperature, aged at 850℃ for 8 h, cooled to 400℃ at a rate of 1℃ / min, and finally water-quenched to room temperature.
[0061] After heat treatment, the internal grain size of the magnet is 1.5-3.1μm, and the coercivity temperature coefficient is -0.14% / K in the temperature range of 300K-673K.
[0062] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A rare-earth permanent magnet material with high temperature stability, characterized in that: The composition and content of the rare earth permanent magnet material are expressed by the formula: Sm x Co 100-x-y-z Hf y M z Where M is one or more of Zr, Fe, and Cu, and x, y, and z represent mass percentages, 24 <x<27,0<y≤2,0<z<30; The rare-earth permanent magnet material exhibits a typical cellular structure with an average cell size of 78-85 nm, forming a 1:5H cell wall phase with a thickness of 8-10 nm, and a plate-like phase density of 0.025-0.03 nm. -1 The elements inside the material are evenly distributed; The specific steps for preparing the rare-earth permanent magnet material with high temperature stability are as follows: ① Spark plasma sintering: Sm... x Co 100-x-y-z Hf y M z Powder is poured into a graphite mold and formed into a bulk material using spark plasma sintering technology. The sintering temperature is 800~1000ºC, the sintering pressure is 20~80MPa, the sintering time is 0.5~20min, and the vacuum degree is less than 10Pa before spark plasma sintering and throughout the sintering process. ② Heat treatment: The obtained bulk material is encapsulated in a quartz tube for solution and aging heat treatment. The solution temperature is 1050-1150℃ and the solution time is 0.5-8 h. Then, it is water-quenched to room temperature, and then the bulk material is aged at 800-950℃ for 5-25 h. Then, it is cooled to 400℃ at a cooling rate of 0.5-1℃ / min, and finally water-quenched to room temperature.
2. The rare-earth permanent magnet material with high temperature stability according to claim 1, characterized in that: In step ①, the sintering temperature is 950ºC, the sintering pressure is 50MPa, and the sintering time is 5min; In step ②, the solution temperature is 1100℃ and the solution time is 4 h; the aging temperature is 800℃ and the aging time is 10 h; then it is cooled to 400℃ at a cooling rate of 1℃ / min; and finally, it is water quenched to room temperature.
3. The rare-earth permanent magnet material with high temperature stability according to claim 1, characterized in that, In step ①, a rapidly quenched alloy strip is prepared by melt rapid quenching, and the alloy strip is broken into the Sm alloy strip under a protective atmosphere. x Co 100-x-y-z Hf y M z powder.
4. The rare-earth permanent magnet material with high temperature stability according to claim 1, characterized in that: The rare earth permanent magnet material has an internal grain size of 1-4 μm; and its coercivity temperature coefficient is -0.14 to -0.17 % / K in the temperature range of 300 K to 673 K.