CN-119400536-B - High-resistivity NdFeB permanent magnet material and high-flux preparation method thereof

Abstract

The invention discloses a high-resistivity NdFeB permanent magnet material and a high-flux preparation method thereof. Preparing a metal sheath with proper size, assembling NdFeB, ndDyTbFeB metal strips and rare earth alloy diffusion source strips into a groove of the metal sheath according to a mutual staggered arrangement method of the metal strips and the diffusion source strips, performing vacuum electron beam welding and hot isostatic pressing treatment, slicing and sealing the obtained multi-element, performing heat treatment, and finally screening to obtain the high-resistivity NdFeB permanent magnetic material. The high-flux preparation method based on diffusion polynary can obtain a large number of parallel samples in a short time, and combines the high-flux test characterization method to rapidly screen a proper diffusion source and heat treatment temperature, thereby efficiently developing the high-resistivity NdFeB permanent magnet material.

Inventors

• JIN JIAYING
• Bu Mengfan
• Meng Ruiyang
• REN SHAOQING
• XIN BO
• YAN MI

Assignees

• 浙江大学
• 包头稀土研究院

Dates

Publication Date

20260505

Application Date

20241105

Claims (5)

1. 1. The high-flux preparation method of the high-resistivity NdFeB permanent magnetic material is characterized by comprising the following steps of: (1) Preparing an oblong sheath with the length, width and height dimensions of l multiplied by m multiplied by n and a cover with the length, width and height dimensions of l multiplied by m multiplied by k, and processing a rectangular groove in the sheath; (2) Preparing a magnet strip M with the length, width and height dimensions of a multiplied by b multiplied by d, preparing a diffusion source strip T with the length, width and height dimensions of a multiplied by c multiplied by d, and carrying out surface grinding and polishing treatment, wherein in terms of millimeters, a is more than or equal to 10 and more than or equal to 3, b is more than or equal to 10 and more than or equal to 3, c is more than or equal to 0.5, and d is more than or equal to 3; The magnet bar M in the step (2) is selected from one or more of NdFeB magnet and NdDyTbFeB magnet, wherein the NdFeB magnet comprises (Nd x Pr y A z D 1-x-y-z ) a Fe bal M c B e , nd is rare earth element neodymium, pr is rare earth element praseodymium, A is one or more elements of rare earth La, ce and Y, D is one or more elements of other rare earth except Dy, tb, nd, pr, la, ce, Y, fe is iron element, B is boron element and M is one or more elements of Al, ga, cu, ti, cr, mn, mo, nb, P, si, ta, V, zr, ni, co, wherein the NdDyTbFeB magnet comprises (Nd x' Pr y' R z' E 1-x'-y'-z' ) b Fe bal N d B f , R is one or two elements of rare earth Dy and Tb, E is one or more elements of other rare earth except Dy, tb, nd, pr, la, ce, Y, and N is one or more elements of Al, ga, cu, ti, cr, mn, mo, nb, P, si, ta, V, zr, ni, co, and the weight percentages are as follows 0.2≤x≤1,0≤y≤0.5,0≤z≤0.8,28.5≤a≤33.5,0.3≤c≤6,0.85≤e≤1.5,0.5≤x'≤1,0≤y'≤0.4,0.05≤z'≤0.5,27≤b≤33.5,0.2≤d≤6,0.85≤f≤1.5; The diffusion source strip T is selected from one or more of S g Fe bal Q h Z t , wherein S is one or more elements in rare earth Dy, tb, nd, pr, gd, ho, fe is an iron element, Q is one or more elements in Al, ga, cu, ni, co, Z is one or more elements in Sn, si, zn, zr, pb, and the conditions that g is more than or equal to 0.5 and less than or equal to 0.8, h is more than or equal to 0.05 and less than or equal to 0.45,0.05 and T is less than or equal to 0.45 are satisfied; (3) The magnet strips and the diffusion source strips are assembled in the rectangular groove in a staggered mode, the cover is covered, and vacuum electron beam welding is conducted; (4) Carrying out hot isostatic pressing treatment on the welded sheath to obtain a diffusion multi-element joint, wherein the hot isostatic pressing treatment temperature is 650-1000 ℃, the time is 2-5 h, and the pressure is 50-300 MPa; (5) Cutting the diffusion multi-section into a plurality of pieces parallel to the oblong surface, sealing the pipe, and performing diffusion heat treatment at different temperatures or times according to the subsequent test requirements to obtain a plurality of groups of diffusion multi-section of the high-resistivity NdFeB permanent magnet material under different heat treatment conditions, wherein the diffusion heat treatment time is 2-30 days, and the diffusion heat treatment temperature is 800-1100 ℃; (6) And performing resistivity and magnetic performance tests on each interface of the obtained diffusion polynary section of the NdFeB permanent magnet material, selecting an interface meeting the requirements of required resistivity and magnetic performance, and preparing the NdFeB permanent magnet material according to the constituent components on two sides of the interface and corresponding heat treatment conditions.
2. 2. The method of claim 1, wherein the jacket material in step (1) is one of 304 stainless steel, pure iron, cr metal.
3. 3. The method according to claim 1, wherein the vacuum degree of vacuum electron beam welding in the step (3) is 5 x 10 -5 ~5×10 -4 Pa, and the weld width is 0.5 to 1.5 mm.
4. 4. The method of claim 1, wherein the tube sealing in step (5) is performed under an argon atmosphere of 0.03-0.06 MPa.
5. 5. The high-resistivity NdFeB permanent magnet material prepared by the method of any one of claims 1 to 4.

Description

High-resistivity NdFeB permanent magnet material and high-flux preparation method thereof Technical Field The invention relates to the field of rare earth permanent magnets, in particular to a high-resistivity NdFeB permanent magnet material and a high-flux preparation method thereof. Background Along with the continuous optimization of the social energy structure, the demands of low-carbon economic fields such as energy-saving household appliances, new energy automobiles, wind power generation and the like on permanent magnet materials are greatly increased. The permanent magnet motor is favored in the market compared with the excitation motor because of the advantages of high efficiency, low energy consumption, good stability, weight and volume. With the rapid development of low-carbon economy and the increasing wide application field, the market has put forward higher performance requirements on the permanent magnet motor, and the development of a safer, reliable and efficient permanent magnet motor is urgently required. The permanent magnet motor is a permanent magnet NdFeB. The operating environment temperature of the permanent magnet synchronous traction motor for the new energy automobile and the permanent magnet synchronous generator for the wind power generator is often up to 150 ℃ or even 250 ℃. However, since the curie temperature of the neodymium-iron-boron magnet is low (about 312 ℃), in such a high-temperature environment, the conventional neodymium-iron-boron magnet is prone to thermal demagnetization, resulting in a decrease in magnetic properties, and thus efficient operation of the permanent magnet motor cannot be ensured. At present, expensive and scarce heavy rare earth elements such as Dy, tb and the like are mostly adopted to increase the coercive force, so that the cost is greatly increased. The method of adding a water cooling device and the like can be adopted to reduce the temperature of the rotor, but the structural design of the motor can be limited, so that the material problem can not be fundamentally solved. The heating value of the rotor is mainly determined by the resistivity of the rotor, and the scattering rate of electrons is improved by introducing scattering elements with high resistivity into NdFeB, so that the heat generation amount can be reduced. Most of the current researches introduce insulating oxide particles containing Si, zn and Sn, etc., so as to improve the resistivity, and the process tends to lead to the great reduction of the magnetic performance. A continuous rare earth oxide grain boundary phase is formed along a main phase boundary layer by adopting a grain boundary diffusion method, so that the resistivity can be improved while the coercive force is ensured, and therefore, the grain boundary diffusion method is an alternative method for researching and preparing the NdFeB permanent magnetic material with high resistivity. However, the grain boundary diffusion method depends on a large number of experiments, and only needs to explore a proper diffusion substrate and diffusion source components and an optimal diffusion process, so that the high-resistivity NdFeB permanent magnet material meeting the actual application requirements can be obtained. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a high-resistivity NdFeB permanent magnetic material and a high-flux preparation method thereof. According to the invention, a high-flux experimental method is adopted, a large number of parallel samples are obtained in a short time by preparing multiple sections, and the experimental efficiency can be effectively improved by combining the high-flux test characterization method. By adopting a diffusion multinary joint method, the interfaces are tightly combined by applying hot isostatic pressing, so that higher mechanical properties can be obtained. Through reasonable design of the components of the diffusion layer, heavy rare earth is diffused into the main phase to form a core-shell structure, so that the wettability and the resistivity of the grain boundary phase are improved, and the overall resistivity is improved under the condition of not losing the magnetic performance. The invention provides a high-flux preparation method of a high-resistivity NdFeB permanent magnet material, which comprises the following steps: (1) Preparing an oblong sheath with a length, width and height dimension of l x m x n and a cover with a length, width and height dimension of l x m x k, and processing a rectangular groove in the sheath; (2) Preparing a magnet strip M with a length, width and height dimension of a being a, b and d, preparing a diffusion source strip T with a length, width and height dimension of a being a, c and d, and carrying out surface grinding and polishing treatment, wherein in terms of millimeters, a is more than or equal to 10 and more than or equal to 3, b is more than or equal to 10 and more than or equa