High-performance rare earth permanent magnet material and preparation process thereof

Abstract

This invention relates to the field of permanent magnet materials, specifically to a high-performance rare-earth permanent magnet material and its preparation process. The preparation process of a high-performance rare-earth permanent magnet material includes: preparing a magnetic matrix; preparing a magnetic blank; and preparing the rare-earth permanent magnet material. This invention, through the diffusion of Dy-Ni-Gd-Co alloy at the grain boundaries on the upper and lower surfaces of the magnetic matrix, allows Dy and Gd to synergistically enhance the anisotropic field of the magnetic crystal, while better maintaining the remanence of the magnet at high temperatures. Co atoms can enter the lattice of the main phase, forming a solid solution, partially replacing Fe, reducing lattice defects in the main phase, and increasing the magnetic moment interaction strength of the main phase, thus delaying the thermal vibration decay of the magnetic moment at high temperatures. Ni promotes the rapid diffusion of Dy, Gd, and Co atoms into the grain boundaries inside the magnet, and can also form high-melting-point intermetallic compounds with rare-earth elements, significantly improving the high-temperature stability of the grain boundary phase, thereby reducing overall magnetic flux loss.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet materials, specifically to a high-performance rare-earth permanent magnet material and its preparation process. Background Technology

[0002] Rare earth permanent magnet materials, especially neodymium iron boron permanent magnets, have become core basic materials in high-end fields such as new energy vehicle motors, wind power generation equipment, and aerospace components due to their excellent magnetic properties such as high energy product and high coercivity. Their performance directly determines the efficiency and reliability of the end equipment.

[0003] Currently, the Curie temperature of traditional NdFeB magnets is only 312℃. At high temperatures, the anisotropic field of the magnetocrystalline structure decays drastically, making them prone to demagnetization or even failure, which is insufficient to meet the requirements of continuous high-temperature operation. Although adding heavy rare earth elements such as Dy and Tb can improve coercivity, it will dilute the main phase and reduce the magnetic energy product, creating a performance contradiction between coercivity and magnetic energy product. At the same time, the grain boundary phase of the magnet is mostly a low-melting-point rare earth-rich phase, which is prone to softening and loss at high temperatures, leading to the failure of exchange coupling between main phase grains and accelerating the decay of magnetic properties. In addition, NdFeB materials are rich in active rare earth phases in their multiphase microstructure, making them chemically active. They are prone to electrochemical corrosion in harsh environments such as humidity and salt spray, leading to magnetic property deterioration or even structural pulverization, which seriously threatens the long-term reliability of the device.

[0004] Therefore, it is necessary to propose a high-performance rare-earth permanent magnet material with excellent thermal stability and corrosion resistance, as well as its preparation process, in order to extend its service life. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a high-performance rare-earth permanent magnet material and its preparation process.

[0006] This invention provides a preparation process for high-performance rare-earth permanent magnet materials, comprising the following steps: S1: Preparation of the magnetic substrate Dy-Cu-Ga-Zr alloy powder and Pr-Nd-Al-Cu-Ga alloy powder were prepared separately, and then the two were mixed and ball-milled to prepare a mixed auxiliary alloy powder. Then, magnetic powder was prepared using iron, ferroboron and praseodymium as raw materials, and mixed with the mixed auxiliary alloy powder, compacted, oriented, statically pressed, sintered and tempered to obtain a magnetic matrix. S2: Preparation of the magnetic blank S2.1: Dy, Ni, Gd and Co are placed in the water-cooled copper crucible of the electric arc furnace in order of melting point from high to low. A getter is placed on the edge of the crucible. The mixture is then melted in an argon atmosphere and cooled to room temperature in the furnace to obtain an alloy ingot. S2.2: The above alloy ingot is crushed using a pulverizer and then sieved using a vibrating screener to obtain Dy-Ni-Gd-Co alloy powder with a particle size of less than 5μm. S2.3: Polish the surface of the magnetic substrate obtained in step S1.5 with sandpaper, then ultrasonically clean it with deionized water and anhydrous ethanol for 5-10 minutes respectively, and then vacuum dry it to obtain the pretreated magnetic substrate. S2.4: The pretreated magnetic substrate is placed in a magnetron sputtering system, and the Dy-Ni-Gd-Co alloy powder is magnetron sputtered onto the upper and lower surfaces of the pretreated magnetic substrate to form an alloy coating with a thickness of 1.8-2.2 μm. The substrate is then wrapped with molybdenum foil, placed in a vacuum tube furnace, heated to 800-900℃ at 5-10℃ / min, and held for diffusion for 4-5 hours. The substrate is then tempered at 450-500℃ for 1-2 hours to obtain a magnetic blank. S3: Preparation of rare earth permanent magnet materials Nano-zirconia was silanized and zinc-titanium alloy powder was activated. Then, the modified nano-zirconia was mixed with an ethanol aqueous solution and ball-milled. Then, active zinc-titanium alloy powder, passivator and binder were added and ball-milled again to prepare a nano-doped coating. This coating was then uniformly coated on the surface of the above-mentioned magnetic blank and cured to obtain rare earth permanent magnet material.

[0007] Furthermore, S1 specifically includes the following steps: S1.1: Place Dy, Cu, Ga, and Zr in a vacuum induction casting furnace and melt them at 1500-1550℃ for 25-35 minutes under argon protection. Then cool them at a cooling rate of 10-15 m / s to obtain Dy-Cu-Ga-Zr rapid solidification sheets of 0.2-0.4 mm. Then grind and pulverize them into Dy-Cu-Ga-Zr alloy powder of 300 μm. S1.2: Pr, Nd, Al, Cu, and Ga are placed in a vacuum induction casting furnace and melted at 1450-1550℃ for 20-30 minutes under argon protection. Then, they are cooled at a cooling rate of 10-15 m / s to obtain Pr-Nd-Al-Cu-Ga rapid solidification sheets of 0.2-0.4 mm. These sheets are then ground and pulverized into Pr-Nd-Al-Cu-Ga alloy powder of 300 μm. S1.3: Add the above Dy-Cu-Ga-Zr alloy powder and Pr-Nd-Al-Cu-Ga alloy powder into a ball mill at a mass ratio of (1.8-2.4):1, use anhydrous ethanol as the ball milling medium, and ball mill at 200-300 r / min for 36-40 h at a solid-liquid ratio of 1:1 to obtain mixed auxiliary alloy powder. S1.4: Iron, ferroboron and praseodymium neodymium are placed in a vacuum rapid solidification furnace and melted for 1-2 hours. Then, they are rapidly solidified and cooled to room temperature at 3-5 m / s to form a rapid solidification belt. The rapid solidification belt is then subjected to hydrogen explosion treatment and air jet milling to obtain magnetic powder with a particle size of 2.5-3 μm. S1.5: Add the above mixed auxiliary alloy powder to the above magnetic powder, stir and mix for 1-2 hours, then compact and oriented under a magnetic field of 1800 kA / m, and after isostatic pressing at 200-300 MPa, place it in a vacuum sintering furnace and sinter at 1100-1200℃ for 2.5-3.5 hours, and then place it in a tubular vacuum slide rail furnace and temper at 400-500℃ for 2-3 hours to obtain the magnetic matrix.

[0008] Furthermore, S3 specifically includes the following steps: S3.1: Mix nano-zirconia with silane coupling agent KH-560 and ultrasonically disperse for 30-40 min to obtain modified nano-zirconia. Soak zinc-titanium alloy powder in 5% citric acid solution for 10-20 min, then wash and dry to obtain activated zinc-titanium alloy powder. S3.2: Add the above modified nano-zirconia to a 50% ethanol aqueous solution, ball mill for 1-2 hours, then add the above activated zinc-titanium alloy powder, passivator and binder, and continue ball milling for 1-2 hours to obtain nano-doped coating. S3.3: The above-mentioned nano-doped coating is uniformly coated on the surface of the magnetic blank obtained in step S2.4, pre-baked at 80-90℃ for 10-20 min, then heated to 210-220℃ at 5℃ / min and held for 20-30 min to form a protective coating, thereby obtaining rare earth permanent magnet material.

[0009] Furthermore, the composition of the Dy-Cu-Ga-Zr alloy powder is: 76-78wt%Dy, 8-10wt%Cu, 4-6wt%Ga, with the balance being Zr.

[0010] Furthermore, the composition of the Pr-Nd-Al-Cu-Ga alloy powder is: 43-45wt%Pr, 42-44wt%Dy, 4-6wt%Ga, 1-3wt%Al, with the balance being Cu.

[0011] Furthermore, the amount of mixed auxiliary alloy powder added is 2.6-3% of the magnetic powder mass, and the composition of the magnetic powder is: 15.8-16.4wt% Nd, 4.6-6.2wt% B, 5-6wt% Pr, with the balance being Fe and unavoidable impurities.

[0012] Furthermore, the alloy ingot has the following composition: 53-55wt%Dy, 7.6-8.8wt%Ni, 13-15wt%Gd, with the balance being Co.

[0013] Furthermore, by mass percentage, the raw material composition of the nano-doped coating is: 26-28% zinc-titanium alloy powder, 1.5-2.3% nano-zirconia, 4-6% silane coupling agent KH-560, 1-1.5% passivating agent, 8-10% binder, and the balance being an aqueous ethanol solution.

[0014] Furthermore, the passivating agent is sodium phosphomolybdate; the binder is γ-(2,3-epoxypropoxy)propyltrimethoxysilane; the zinc-titanium alloy powder has a particle size of 5-10 μm, wherein the atomic percentage of Zn to Ti is 88:12.

[0015] A high-performance rare-earth permanent magnet material, which is prepared by the preparation process of a high-performance rare-earth permanent magnet material described in any one of the above claims.

[0016] The present invention has the following advantages: 1. In this invention, by diffusing Dy-Ni-Gd-Co alloy at the grain boundaries on the upper and lower surfaces of the magnetic matrix, Dy and Gd can synergistically enhance the anisotropic field of the magnetocrystalline material, while better maintaining the remanence of the magnet at high temperatures. Co atoms can enter the lattice of the main phase to form a solid solution, partially replacing Fe, reducing lattice defects in the main phase, and increasing the magnetic moment interaction strength of the main phase, thus delaying the thermal vibration decay of the magnetic moment at high temperatures. The alloy formed by Ni with Dy, Gd, Co, etc., can form a liquid phase at a diffusion temperature of 800-900℃, promoting the rapid diffusion of Dy, Gd, and Co atoms into the grain boundaries inside the magnet, greatly improving the utilization efficiency and diffusion uniformity of heavy rare earth elements. At the same time, after diffusion, it can form high-melting-point intermetallic compounds with rare earth elements, significantly improving the high-temperature stability of the grain boundary phase, thereby reducing the overall magnetic flux loss.

[0017] 2. In this invention, by mixing Dy-Cu-Ga-Zr alloy powder and Pr-Nd-Al-Cu-Ga alloy powder to form auxiliary alloy powder, and then mixing and sintering it with magnetic powder, Dy atoms in Dy-Cu-Ga-Zr diffuse along the grain boundaries through the liquid phase and selectively replace Pr / Nd atoms in the surface region of the main phase grains, forming a composite shell. This enhances the grains' ability to resist nucleation and growth in the reverse magnetization domain. Meanwhile, Pr-Nd-Al-Cu-Ga can supplement the required Pr and Nd at the grain boundaries, ensuring the formation of a continuous, non-magnetic rare-earth-rich grain boundary phase. This effectively isolates the magnetic exchange coupling between the main phase grains, reduces mutual interference, and thus synergistically enhances the magnetic matrix. In addition to coercivity, the Zr precipitates in Dy-Cu-Ga-Zr pin the grain boundaries, inhibiting excessive growth of the main phase grains. Pr in Pr-Nd-Al-Cu-Ga can reduce the growth rate of the main phase grains. The synergistic effect of the two can avoid the decrease in magnetic energy product caused by excessively fine grains, and also prevent the decay of coercivity caused by excessively coarse grains. The Al in Pr-Nd-Al-Cu-Ga and the Ga in the two alloys work together to improve the wettability between the grain boundary phase and the main phase, so that the grain boundary phase can closely adhere to the surface of the main phase grains to form a continuous and uniform isolation layer, reduce the mutual interference of magnetic domains of adjacent main phase grains, and inhibit the expansion of antimagnetic domains, thereby further improving the magnetic properties of the magnetic matrix.

[0018] 3. In this invention, nano-zirconia is modified by silanization, then mixed with an ethanol aqueous solution and ball-milled. Activated zinc-titanium alloy powder, passivating agent, and binder are added to form a nano-doped coating, which is then coated onto the surface of the magnetic blank. After curing to form a protective coating, Zn preferentially undergoes oxidation as a "sacrificial anode" in a corrosive environment, while the magnetic blank acts as a "cathode" and is protected from self-corrosion. Ni refines the corrosion products of zinc, forming a dense corrosion product film that covers the coating surface, further preventing the penetration of corrosive media and extending the protective life of the anode. Simultaneously, the modified nano-zirconia can uniformly fill the pores between the zinc-titanium alloy powder, reducing the porosity of the coating and significantly reducing the penetration channels of corrosive media. This effectively improves the corrosion resistance of rare earth permanent magnet materials while maintaining the original magnetic properties of the magnetic blank. Furthermore, the uniform dispersion of nano-zirconia in the coating forms a wear-resistant reinforcing phase, enabling the coating to resist frictional wear during assembly and transportation, as well as particle erosion in the service environment. This improves the wear resistance of the coating and prevents corrosion failure due to surface wear exposing the substrate. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation process of the high-performance rare-earth permanent magnet material used in an embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0021] Example 1: A preparation process for a high-performance rare-earth permanent magnet material, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of the magnetic substrate S1.1: Dy, Cu, Ga, and Zr are placed in a vacuum induction casting furnace and melted at 1500℃ for 25 minutes under argon protection. Then, they are cooled at a cooling rate of 10 m / s to obtain 0.2 mm Dy-Cu-Ga-Zr rapid solidification sheets. These sheets are then ground and pulverized into Dy-Cu-Ga-Zr alloy powder with a thickness of about 300 μm. The composition of the Dy-Cu-Ga-Zr alloy powder is: 76 wt% Dy, 8 wt% Cu, 4 wt% Ga, and 12 wt% Zr. S1.2: Pr, Nd, Al, Cu, and Ga are placed in a vacuum induction casting furnace and melted at 1450℃ for 20 minutes under argon protection. Then, they are cooled at a cooling rate of 10 m / s to obtain 0.2 mm Pr-Nd-Al-Cu-Ga rapid solidification sheets. These sheets are then ground and pulverized into Pr-Nd-Al-Cu-Ga alloy powder with a thickness of about 300 μm. The composition of the Pr-Nd-Al-Cu-Ga alloy powder is: 43 wt% Pr, 42 wt% Dy, 4 wt% Ga, 1 wt% Al, and 10 wt% Cu. S1.3: The above Dy-Cu-Ga-Zr alloy powder and Pr-Nd-Al-Cu-Ga alloy powder were added to a ball mill at a mass ratio of 1.8:1, and anhydrous ethanol was used as the ball milling medium. The mixture was ball milled at 200 r / min for 36 h at a solid-liquid ratio of 1:1 to obtain mixed auxiliary alloy powder. S1.4: Iron, ferroboron and praseodymium neodymium are placed in a vacuum rapid solidification furnace and melted for 1 hour. Then, they are rapidly solidified and cooled to room temperature at 3 m / s to form a rapid solidification belt. The rapid solidification belt is then subjected to hydrogen explosion treatment and air jet milling to obtain magnetic powder with a particle size of about 2.5 μm. S1.5: The above mixed auxiliary alloy powder is added to the above magnetic powder and stirred for 1 hour. Then it is compacted and oriented under a magnetic field of 1800 kA / m. After isostatic pressing at 200 MPa, it is placed in a vacuum sintering furnace and sintered at 1100℃ for 2.5 hours. Then it is placed in a tubular vacuum slide rail furnace and tempered at 400℃ for 2 hours to obtain a magnetic matrix. The amount of mixed auxiliary alloy powder added is 2.6% of the mass of the magnetic powder, and the composition of the magnetic powder is: 15.8 wt% Nd, 4.6 wt% B, 5 wt% Pr and the balance is Fe and unavoidable impurities. S2: Preparation of the magnetic blank S2.1: Dy, Ni, Gd, and Co are placed in a water-cooled copper crucible of an electric arc furnace in descending order of melting point. A getter is placed on the edge of the crucible, and the mixture is then smelted in an argon atmosphere. After cooling to room temperature in the furnace, an alloy ingot is obtained. The alloy ingot has the following composition: 53wt% Dy, 7.6wt% Ni, 13wt% Gd, and 26.4wt% Co. S2.2: The above alloy ingot is crushed using a pulverizer and then sieved using a vibrating screener to obtain Dy-Ni-Gd-Co alloy powder with a particle size of less than 5μm. S2.3: The magnetic substrate obtained in step S1.5 is polished with sandpaper, then ultrasonically cleaned with deionized water and anhydrous ethanol for 5 minutes each, and then vacuum dried to obtain the pretreated magnetic substrate. S2.4: The pretreated magnetic substrate is placed in a magnetron sputtering system, and the Dy-Ni-Gd-Co alloy powder is magnetron sputtered on the upper and lower surfaces of the pretreated magnetic substrate to form an alloy coating with a thickness of 1.8 μm. The substrate is then wrapped with molybdenum foil, placed in a vacuum tube furnace, heated to 800°C at 5°C / min, and held for diffusion for 4 hours. The substrate is then tempered at 450°C for 1 hour to obtain a magnetic blank. S3: Preparation of rare earth permanent magnet materials S3.1: Nano-zirconia was mixed with silane coupling agent KH-560 and ultrasonically dispersed for 30 min to obtain modified nano-zirconia. Zinc-titanium alloy powder was soaked in 5% citric acid solution for 10 min, and then washed and dried to obtain activated zinc-titanium alloy powder. The particle size of the zinc-titanium alloy powder was 5 μm, and the atomic percentage of Zn to Ti was 88:12. S3.2: The modified nano-zirconia was added to a 50% ethanol aqueous solution and ball-milled for 1 hour. Then, the activated zinc-titanium alloy powder, sodium phosphomolybdate, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were added, and ball-milling was continued for 1 hour to obtain a nano-doped coating. The raw material composition of the nano-doped coating, by mass percentage, is: 26% zinc-titanium alloy powder, 1.5% nano-zirconia, 4% silane coupling agent KH-560, 1% sodium phosphomolybdate, 8% γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and the remainder is an ethanol aqueous solution. S3.3: The above-mentioned nano-doped coating is uniformly coated on the surface of the magnetic blank obtained in step S2.4, pre-baked at 80°C for 10 min, then heated to 210°C at 5°C / min and held for 20 min to form a protective coating, thereby obtaining rare earth permanent magnet material.

[0022] Example 2: A preparation process for a high-performance rare-earth permanent magnet material, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of the magnetic substrate S1.1: Dy, Cu, Ga, and Zr are placed in a vacuum induction casting furnace and melted at 1525℃ for 30 minutes under argon protection. Then, they are cooled at a cooling rate of 12.5 m / s to obtain 0.3 mm Dy-Cu-Ga-Zr rapid solidification sheets, which are then ground and pulverized into Dy-Cu-Ga-Zr alloy powder with a thickness of about 300 μm. The composition of the Dy-Cu-Ga-Zr alloy powder is: 77 wt% Dy, 9 wt% Cu, 5 wt% Ga, and 9 wt% Zr. S1.2: Pr, Nd, Al, Cu, and Ga are placed in a vacuum induction casting furnace and melted at 1500℃ for 25 minutes under argon protection. Then, they are cooled at a cooling rate of 12.5 m / s to obtain 0.3 mm Pr-Nd-Al-Cu-Ga rapid solidification sheets. These sheets are then ground and pulverized into Pr-Nd-Al-Cu-Ga alloy powder with a thickness of about 300 μm. The composition of the Pr-Nd-Al-Cu-Ga alloy powder is: 44 wt% Pr, 43 wt% Dy, 5 wt% Ga, 2 wt% Al, and 6 wt% Cu. S1.3: The above Dy-Cu-Ga-Zr alloy powder and Pr-Nd-Al-Cu-Ga alloy powder were added to a ball mill at a mass ratio of 2.1:1, and anhydrous ethanol was used as the ball milling medium. The mixture was ball milled at 250 r / min for 38 h at a solid-liquid ratio of 1:1 to obtain mixed auxiliary alloy powder. S1.4: Iron, ferroboron and praseodymium neodymium are placed in a vacuum rapid solidification furnace and melted for 1.5 hours. Then, they are rapidly solidified and cooled to room temperature at 4 m / s to form a rapid solidification belt. The rapid solidification belt is then subjected to hydrogen explosion and air jet milling to obtain magnetic powder with a particle size of about 2.8 μm. S1.5: The above mixed auxiliary alloy powder is added to the above magnetic powder and stirred for 1.5 hours. Then it is compacted and oriented under a magnetic field of 1800 kA / m. After isostatic pressing at 250 MPa, it is placed in a vacuum sintering furnace and sintered at 1150℃ for 3 hours. Then it is placed in a tubular vacuum slide rail furnace and tempered at 450℃ for 2.5 hours to obtain a magnetic matrix. The amount of mixed auxiliary alloy powder added is 2.8% of the mass of the magnetic powder, and the composition of the magnetic powder is: 16.1 wt% Nd, 5.4 wt% B, 5.5 wt% Pr, with the balance being Fe and unavoidable impurities. S2: Preparation of the magnetic blank S2.1: Dy, Ni, Gd, and Co are placed in a water-cooled copper crucible of an electric arc furnace in descending order of melting point. A getter is placed on the edge of the crucible, and the mixture is then smelted in an argon atmosphere. After cooling to room temperature in the furnace, an alloy ingot is obtained. The alloy ingot has the following composition: 54wt%Dy, 8.2wt%Ni, 14wt%Gd, and 23.8wt%Co. S2.2: The above alloy ingot is crushed using a pulverizer and then sieved using a vibrating screener to obtain Dy-Ni-Gd-Co alloy powder with a particle size of less than 5μm. S2.3: The magnetic substrate obtained in step S1.5 is polished with sandpaper, then ultrasonically cleaned with deionized water and anhydrous ethanol for 7.5 min each, and then vacuum dried to obtain the pretreated magnetic substrate. S2.4: The pretreated magnetic substrate is placed in a magnetron sputtering system, and the Dy-Ni-Gd-Co alloy powder is magnetron sputtered onto the upper and lower surfaces of the pretreated magnetic substrate to form an alloy coating with a thickness of 2μm. The substrate is then wrapped with molybdenum foil, placed in a vacuum tube furnace, heated to 850℃ at 7.5℃ / min, and held for diffusion for 4.5h. The substrate is then tempered at 475℃ for 1.5h to obtain a magnetic blank. S3: Preparation of rare earth permanent magnet materials S3.1: Nano-zirconia was mixed with silane coupling agent KH-560 and ultrasonically dispersed for 35 min to obtain modified nano-zirconia. Zinc-titanium alloy powder was soaked in 5% citric acid solution for 15 min, and then washed and dried to obtain activated zinc-titanium alloy powder. The particle size of the zinc-titanium alloy powder was about 7.5 μm, and the atomic percentage of Zn to Ti was 88:12. S3.2: The modified nano-zirconia was added to a 50% ethanol aqueous solution and ball-milled for 1.5 h. Then, the activated zinc-titanium alloy powder, sodium phosphomolybdate, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were added, and ball-milling was continued for another 1.5 h to obtain a nano-doped coating. The raw material composition of the nano-doped coating, by mass percentage, is: 27% zinc-titanium alloy powder, 1.9% nano-zirconia, 5% silane coupling agent KH-560, 1.25% sodium phosphomolybdate, 9% γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and the remainder is an ethanol aqueous solution. S3.3: The above-mentioned nano-doped coating is uniformly coated on the surface of the magnetic blank obtained in step S2.4, pre-baked at 85°C for 15 min, then heated to 215°C at 5°C / min and held for 25 min to form a protective coating, thereby obtaining rare earth permanent magnet material.

[0023] Example 3: A preparation process for a high-performance rare-earth permanent magnet material, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of the magnetic substrate S1.1: Dy, Cu, Ga, and Zr are placed in a vacuum induction casting furnace and melted at 1550℃ for 35 minutes under argon protection. Then, they are cooled at a cooling rate of 15 m / s to obtain 0.4 mm Dy-Cu-Ga-Zr rapid solidification sheets. These sheets are then ground and pulverized into Dy-Cu-Ga-Zr alloy powder with a thickness of about 300 μm. The composition of the Dy-Cu-Ga-Zr alloy powder is: 78 wt% Dy, 10 wt% Cu, 6 wt% Ga, and 6 wt% Zr. S1.2: Pr, Nd, Al, Cu, and Ga are placed in a vacuum induction casting furnace and melted at 1550℃ for 30 minutes under argon protection. Then, they are cooled at a cooling rate of 15 m / s to obtain 0.4 mm Pr-Nd-Al-Cu-Ga rapid solidification sheets. These sheets are then ground and pulverized into Pr-Nd-Al-Cu-Ga alloy powder with a thickness of about 300 μm. The composition of the Pr-Nd-Al-Cu-Ga alloy powder is: 45 wt% Pr, 44 wt% Dy, 6 wt% Ga, 3 wt% Al, and 2 wt% Cu. S1.3: The above Dy-Cu-Ga-Zr alloy powder and Pr-Nd-Al-Cu-Ga alloy powder were added to a ball mill at a mass ratio of 2.4:1, and anhydrous ethanol was used as the ball milling medium. The mixture was ball milled at 300 r / min for 40 h at a solid-liquid ratio of 1:1 to obtain mixed auxiliary alloy powder. S1.4: Iron, ferroboron and praseodymium neodymium are placed in a vacuum rapid solidification furnace and melted for 2 hours. Then, they are rapidly solidified and cooled to room temperature at 5 m / s to form a rapid solidification belt. The rapid solidification belt is then subjected to hydrogen explosion treatment and air jet milling to obtain magnetic powder with a particle size of about 3 μm. S1.5: The above mixed auxiliary alloy powder is added to the above magnetic powder and stirred for 2 hours. Then it is compacted and oriented under a magnetic field of 1800 kA / m. After isostatic pressing at 300 MPa, it is placed in a vacuum sintering furnace and sintered at 1200℃ for 3.5 hours. Then it is placed in a tubular vacuum slide rail furnace and tempered at 500℃ for 3 hours to obtain a magnetic matrix. The amount of mixed auxiliary alloy powder added is 3% of the mass of the magnetic powder, and the composition of the magnetic powder is: 16.4 wt% Nd, 6.2 wt% B, 6 wt% Pr, with the balance being Fe and unavoidable impurities. S2: Preparation of the magnetic blank S2.1: Dy, Ni, Gd, and Co are placed in a water-cooled copper crucible of an electric arc furnace in descending order of melting point. A getter is placed on the edge of the crucible, and the mixture is then melted in an argon atmosphere. After cooling to room temperature in the furnace, an alloy ingot is obtained. The alloy ingot has the following composition: 55wt%Dy, 8.8wt%Ni, 15wt%Gd, and 21.2wt%Co. S2.2: The above alloy ingot is crushed using a pulverizer and then sieved using a vibrating screener to obtain Dy-Ni-Gd-Co alloy powder with a particle size of less than 5μm. S2.3: The magnetic substrate obtained in step S1.5 is polished with sandpaper, then ultrasonically cleaned with deionized water and anhydrous ethanol for 10 min each, and then vacuum dried to obtain the pretreated magnetic substrate. S2.4: The pretreated magnetic substrate is placed in a magnetron sputtering system, and the Dy-Ni-Gd-Co alloy powder is magnetron sputtered on the upper and lower surfaces of the pretreated magnetic substrate to form an alloy coating with a thickness of 2.2 μm. The substrate is then wrapped with molybdenum foil, placed in a vacuum tube furnace, heated to 900°C at 10°C / min, and held for diffusion for 5 hours. The substrate is then tempered at 500°C for 2 hours to obtain a magnetic blank. S3: Preparation of rare earth permanent magnet materials S3.1: Nano-zirconia was mixed with silane coupling agent KH-560 and ultrasonically dispersed for 40 min to obtain modified nano-zirconia. Zinc-titanium alloy powder was soaked in 5% citric acid solution for 20 min, and then washed and dried to obtain activated zinc-titanium alloy powder. The particle size of the zinc-titanium alloy powder was about 10 μm, and the atomic percentage of Zn to Ti was 88:12. S3.2: The modified nano-zirconia was added to a 50% ethanol aqueous solution and ball-milled for 2 hours. Then, the activated zinc-titanium alloy powder, sodium phosphomolybdate, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane were added, and ball-milling was continued for 2 hours to obtain a nano-doped coating. The raw material composition of the nano-doped coating, by mass percentage, is: 28% zinc-titanium alloy powder, 2.3% nano-zirconia, 6% silane coupling agent KH-560, 1.5% sodium phosphomolybdate, 10% γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and the balance is an ethanol aqueous solution. S3.3: The above-mentioned nano-doped coating is uniformly coated on the surface of the magnetic blank obtained in step S2.4, pre-baked at 90°C for 20 min, then heated to 220°C at 5°C / min and held for 30 min to form a protective coating, thereby obtaining rare earth permanent magnet material.

[0024] Comparative Example 1 differs from Example 1 in that the Pr-Nd-Al-Cu-Ga alloy powder in step S1.3 is replaced with an equal amount of Dy-Cu-Ga-Zr alloy powder.

[0025] Comparative Example 2 differs from Example 1 in that the Dy-Cu-Ga-Zr alloy powder in step S1.3 is replaced with an equal amount of Pr-Nd-Al-Cu-Ga alloy powder.

[0026] Comparative Example 3 differs from Example 1 in that step S2 is removed and the magnetic blank in step S3 is replaced with a magnetic substrate, i.e., a protective coating is directly prepared on the surface of the magnetic substrate.

[0027] Comparative Example 4 differs from Example 1 in that step S3 is removed.

[0028] Comparative Example 5 differs from Example 1 in that the modified nano-zirconia in step S3.2 is removed.

[0029] Test example: Test 1: The magnetic properties of the rare earth permanent magnet materials prepared in Examples 1-3, Comparative Examples 1-2 and Comparative Example 4 at room temperature were measured using a pulse magnetometer. The test was repeated three times and the average value was taken. The results are shown in Table 1.

[0030] Table 1: Magnetic Performance Test Results of Rare Earth Permanent Magnet Materials

[0031] As shown in Table 1, in Comparative Examples 1 and 2, when only one of Dy-Cu-Ga-Zr alloy powder or Pr-Nd-Al-Cu-Ga alloy powder was added to the magnetic powder, the coercivity and maximum energy product of the rare earth permanent magnet materials were lower than those in Example 1. This shows that by mixing Dy-Cu-Ga-Zr alloy powder and Pr-Nd-Al-Cu-Ga alloy powder to form auxiliary alloy powder, and then mixing and sintering it with magnetic powder, the magnetic properties of the magnetic matrix can be synergistically improved.

[0032] The magnetic properties of the uncoated rare earth permanent magnet material in Comparative Example 4 are almost identical to those of the coated rare earth permanent magnet material in Example 1. This indicates that by modifying the nano-zirconia with silanization, mixing it with an ethanol aqueous solution and ball milling it, and then adding activated zinc-titanium alloy powder, passivator and binder to make a nano-doped coating, which is then coated on the surface of the magnetic blank and cured to form a protective coating, the protective coating can maintain the magnetic properties of the magnetic blank.

[0033] Test 2: The irreversible magnetic flux loss of the rare earth permanent magnet materials prepared in Examples 1-3 and Comparative Example 3 was tested using a Helmholtz coil after being kept at 180℃ for 2 hours. The test was repeated three times and the average value was taken. The results are shown in Table 2.

[0034] Table 2: Test Results of Irreversible Flux Loss in Rare Earth Permanent Magnet Materials

[0035] As shown in Table 2, in Comparative Example 3, the irreversible flux loss rate of the rare earth permanent magnet material prepared without grain boundary diffusion of Dy-Ni-Gd-Co alloy on the magnetic matrix was significantly higher than that in Example 1. This shows that by diffusing Dy-Ni-Gd-Co alloy at the grain boundaries on the upper and lower surfaces of the magnetic matrix, the high-temperature stability of the grain boundary phase can be significantly improved, and the overall flux loss can be reduced.

[0036] Test 3: Referring to GB / T10125-2021 standard, the rare earth permanent magnet materials prepared in Examples 1-3 and Comparative Examples 4-5 were subjected to a continuous salt spray test at 35°C and 500h in 5% NaCl solution to detect the corrosion weight loss rate. The test was repeated three times and the average value was taken. The results are shown in Table 3.

[0037] Table 3: Test Results of Corrosion Resistance of Rare Earth Permanent Magnet Materials

[0038] As shown in Table 3, the corrosion weight loss rate of the uncoated rare earth permanent magnet material in Comparative Example 4 after 500 hours of continuous salt spray was significantly higher than that in Example 1. In Comparative Example 5, after removing the nano-zirconia from the coating, the corrosion weight loss rate of the obtained rare earth permanent magnet material was lower than that in Comparative Example 4, but still higher than that in Example 1. It can be seen that by modifying the nano-zirconia with silanization, mixing it with an ethanol aqueous solution and ball milling it, and adding activated zinc-titanium alloy powder, passivating agent and binder to make a nano-doped coating, and then coating it on the surface of the magnet blank, and curing it to form a protective coating, the corrosion resistance of the rare earth permanent magnet material can be effectively improved.

[0039] Test 4: A friction testing machine was used, with a load of 10N, a sliding speed of 0.1m / s, and a friction time of 30min. 400-mesh SiC sandpaper was used as the grinding material to conduct friction and wear tests on the rare earth permanent magnet materials prepared in Examples 1-3 and Comparative Example 5. After the test, the materials were placed in a water stream containing 20wt% silica particles and rinsed for 60min. The wear volume was measured, and the test was repeated three times. The average value was taken. The results are shown in Table 4.

[0040] Table 4: Test Results of Wear Volume of Rare Earth Permanent Magnet Materials

[0041] As shown in Table 4, after removing the nano-zirconia from the coating in Comparative Example 5, the wear volume of the rare earth permanent magnet material was significantly higher than that in Example 1. This shows that the uniform dispersion of nano-zirconia in the coating can form a wear-resistant reinforcing phase, enabling the coating to resist friction and wear of the magnet during assembly and transportation, as well as particle erosion in the service environment, thereby improving the wear resistance of the coating and preventing corrosion failure caused by surface wear exposing the substrate.

[0042] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A preparation process for a high-performance rare-earth permanent magnet material, characterized in that, Includes the following steps: S1: Preparation of the magnetic substrate Dy-Cu-Ga-Zr alloy powder and Pr-Nd-Al-Cu-Ga alloy powder were prepared separately, and then the two were mixed and ball-milled to prepare a mixed auxiliary alloy powder. Then, magnetic powder was prepared using iron, ferroboron and praseodymium as raw materials, and mixed with the mixed auxiliary alloy powder, compacted, oriented, statically pressed, sintered and tempered to obtain a magnetic matrix. S2: Preparation of the magnetic blank S2.1: Dy, Ni, Gd and Co are placed in the water-cooled copper crucible of the electric arc furnace in order of melting point from high to low. A getter is placed on the edge of the crucible. The mixture is then melted in an argon atmosphere and cooled to room temperature in the furnace to obtain an alloy ingot. S2.2: The above alloy ingot is crushed using a pulverizer and then sieved using a vibrating screener to obtain Dy-Ni-Gd-Co alloy powder with a particle size of less than 5μm. S2.3: Polish the surface of the magnetic substrate obtained in step S1.5 with sandpaper, then ultrasonically clean it with deionized water and anhydrous ethanol for 5-10 minutes respectively, and then vacuum dry it to obtain the pretreated magnetic substrate. S2.4: The pretreated magnetic substrate is placed in a magnetron sputtering system, and the Dy-Ni-Gd-Co alloy powder is magnetron sputtered onto the upper and lower surfaces of the pretreated magnetic substrate to form an alloy coating with a thickness of 1.8-2.2 μm. The substrate is then wrapped with molybdenum foil, placed in a vacuum tube furnace, heated to 800-900℃ at 5-10℃ / min, and held for diffusion for 4-5 hours. The substrate is then tempered at 450-500℃ for 1-2 hours to obtain a magnetic blank. S3: Preparation of rare earth permanent magnet materials Nano-zirconia was silanized and zinc-titanium alloy powder was activated. Then, the modified nano-zirconia was mixed with an ethanol aqueous solution and ball-milled. Then, active zinc-titanium alloy powder, passivator and binder were added and ball-milled again to prepare a nano-doped coating. This coating was then uniformly coated on the surface of the above-mentioned magnetic blank and cured to obtain rare earth permanent magnet material.

2. The preparation process of a high-performance rare-earth permanent magnet material according to claim 1, characterized in that, S1 specifically includes the following steps: S1.1: Place Dy, Cu, Ga, and Zr in a vacuum induction casting furnace and melt them at 1500-1550℃ for 25-35 minutes under argon protection. Then cool them at a cooling rate of 10-15 m / s to obtain Dy-Cu-Ga-Zr rapid solidification sheets of 0.2-0.4 mm. Then grind and pulverize them into Dy-Cu-Ga-Zr alloy powder of 300 μm. S1.2: Pr, Nd, Al, Cu, and Ga are placed in a vacuum induction casting furnace and melted at 1450-1550℃ for 20-30 minutes under argon protection. Then, they are cooled at a cooling rate of 10-15 m / s to obtain Pr-Nd-Al-Cu-Ga rapid solidification sheets of 0.2-0.4 mm. These sheets are then ground and pulverized into Pr-Nd-Al-Cu-Ga alloy powder of 300 μm. S1.3: Add the above Dy-Cu-Ga-Zr alloy powder and Pr-Nd-Al-Cu-Ga alloy powder into a ball mill at a mass ratio of (1.8-2.4):1, use anhydrous ethanol as the ball milling medium, and ball mill at 200-300 r / min for 36-40 h at a solid-liquid ratio of 1:1 to obtain mixed auxiliary alloy powder. S1.4: Iron, ferroboron and praseodymium neodymium are placed in a vacuum rapid solidification furnace and melted for 1-2 hours. Then, they are rapidly solidified and cooled to room temperature at 3-5 m / s to form a rapid solidification belt. The rapid solidification belt is then subjected to hydrogen explosion treatment and air jet milling to obtain magnetic powder with a particle size of 2.5-3 μm. S1.5: Add the above mixed auxiliary alloy powder to the above magnetic powder, stir and mix for 1-2 hours, then compact and oriented under a magnetic field of 1800 kA / m, and after isostatic pressing at 200-300 MPa, place it in a vacuum sintering furnace and sinter at 1100-1200℃ for 2.5-3.5 hours, and then place it in a tubular vacuum slide rail furnace and temper at 400-500℃ for 2-3 hours to obtain the magnetic matrix.

3. The preparation process of a high-performance rare-earth permanent magnet material according to claim 2, characterized in that, S3 specifically includes the following steps: S3.1: Mix nano-zirconia with silane coupling agent KH-560 and ultrasonically disperse for 30-40 min to obtain modified nano-zirconia. Soak zinc-titanium alloy powder in 5% citric acid solution for 10-20 min, then wash and dry to obtain activated zinc-titanium alloy powder. S3.2: Add the above modified nano-zirconia to a 50% ethanol aqueous solution, ball mill for 1-2 hours, then add the above activated zinc-titanium alloy powder, passivator and binder, and continue ball milling for 1-2 hours to obtain nano-doped coating. S3.3: The above-mentioned nano-doped coating is uniformly coated on the surface of the magnetic blank obtained in step S2.4, pre-baked at 80-90℃ for 10-20 min, then heated to 210-220℃ at 5℃ / min and held for 20-30 min to form a protective coating, thereby obtaining rare earth permanent magnet material.

4. The preparation process of a high-performance rare-earth permanent magnet material according to claim 2, characterized in that, The composition of Dy-Cu-Ga-Zr alloy powder is: 76-78wt%Dy, 8-10wt%Cu, 4-6wt%Ga, with the balance being Zr.

5. The preparation process of a high-performance rare-earth permanent magnet material according to claim 2, characterized in that, The composition of Pr-Nd-Al-Cu-Ga alloy powder is: 43-45wt%Pr, 42-44wt%Dy, 4-6wt%Ga, 1-3wt%Al, with the balance being Cu.

6. The preparation process of a high-performance rare-earth permanent magnet material according to claim 2, characterized in that, The amount of mixed auxiliary alloy powder added is 2.6-3% of the magnetic powder mass, and the composition of the magnetic powder is: 15.8-16.4wt% Nd, 4.6-6.2wt% B, 5-6wt% Pr, with the balance being Fe and unavoidable impurities.

7. The preparation process of a high-performance rare-earth permanent magnet material according to claim 1, characterized in that, The alloy ingot has the following composition: 53-55wt%Dy, 7.6-8.8wt%Ni, 13-15wt%Gd, with the balance being Co.

8. The preparation process of a high-performance rare-earth permanent magnet material according to claim 3, characterized in that, The raw material composition of the nano-doped coating, by mass percentage, is: 26-28% zinc-titanium alloy powder, 1.5-2.3% nano-zirconia, 4-6% silane coupling agent KH-560, 1-1.5% passivating agent, 8-10% binder, and the balance is an aqueous ethanol solution.

9. The preparation process of a high-performance rare-earth permanent magnet material according to claim 8, characterized in that, The passivating agent is sodium phosphomolybdate; the binder is γ-(2,3-epoxypropoxy)propyltrimethoxysilane; the zinc-titanium alloy powder has a particle size of 5-10 μm, wherein the atomic percentage of Zn to Ti is 88:

12.

10. A high-performance rare-earth permanent magnet material, characterized in that, It is prepared by the preparation process of a high-performance rare earth permanent magnet material as described in any one of claims 1-9.

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