A thermally deformed NdFeB magnetic ring for magnetic levitation high-speed motor and its preparation method

Abstract

The present invention belongs to the technical field of rare earth permanent magnet materials, and specifically relates to a thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor and a preparation method thereof. The thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor of the present invention comprises a NdFeB magnetic ring body and a terbium metal layer arranged on the surface of the NdFeB magnetic ring body. The raw materials of the NdFeB magnetic ring body include the following components in mass percentage: 40.0-49.0% MQ magnetic powder, 45.0-55.0% NdFeB powder prepared by the HDDR method, and 0.5-5.0% silicon carbide powder. MQ magnetic powder prepared by the traditional rapid quenching method and NdFeB powder prepared by the hydrogen absorption-disproportionation-dehydrogenation-recombination method are used, silicon carbide powder is added, and terbium alloy powder is attached to the surface. Combined with the thermal deformation process and the plasma activation treatment process, a NdFeB magnetic ring with high coercivity and good thermal stability is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth permanent magnet materials, and in particular relates to a thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor and a preparation method thereof. Background Art

[0002] Magnetic levitation high-speed motors offer advantages such as high energy density, energy conservation and environmental protection, low noise, high efficiency, and long life. Their core components are primarily made of neodymium iron boron permanent magnets, most of which are bonded or sintered magnetic rings, or by splicing tile-shaped magnets into rings. The use of organic adhesives in the preparation of bonded and spliced ​​magnetic rings reduces the overall magnetic properties of the rings. Processing limitations in sintered magnetic rings result in relatively low orientation and magnetic properties. Furthermore, during the splicing of tile-shaped magnets, significant magnetic flux leakage occurs between the poles, leading to unstable performance during the application of the magnetic levitation high-speed motor.

[0003] Thermally deformed NdFeB magnets feature fine grain size, excellent temperature stability, and strong corrosion resistance. They also feature a stable output waveform. The magnetic rings produced using this thermal deformation process are integrally formed, eliminating the need for splicing, making them suitable for high-speed magnetic levitation motors. However, due to the high speeds of these motors, the magnetomotive force harmonics generated by the fundamental and harmonic currents produce significant eddy current losses in the rotor. The high-speed rotation of the rotor also generates significant friction losses, which can easily lead to excessive rotor temperatures, demagnetization of the thermally deformed magnets, and reduced motor efficiency. The high speeds of these motors also generate high centrifugal forces, which can easily cause the magnetic rings to break. Therefore, improving the temperature stability and mechanical strength of thermally deformed magnets is crucial. Summary of the Invention

[0004] The purpose of the present invention is to address the above problems and provide a thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor with high remanence, low temperature coefficient and high mechanical strength, which can improve the energy efficiency of the magnetic levitation high-speed motor.

[0005] The thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor in the technical solution of the present invention includes a NdFeB magnetic ring body and a terbium metal layer arranged on the surface of the NdFeB magnetic ring body. The raw materials of the NdFeB magnetic ring body include the following components in mass percentage: 40.0-49.0% MQ magnetic powder, 45.0-55.0% NdFeB powder prepared by the HDDR method, and 0.5-5.0% silicon carbide powder.

[0006] The NdFeB powder prepared in this application using the hydrogen absorption-disproportionation-dehydrogenation-recombination (HDDR) method references patent CN109659108A. This method produces NdFeB powder with high anisotropy and high coercivity. When mixed with MQ magnetic powder prepared by the traditional rapid quenching method, the resulting magnetic rings, produced through a thermal deformation process, exhibit both high remanence and high coercivity, effectively improving the thermal stability of the thermally deformed magnetic rings. Silicon carbide powder can effectively increase the resistivity of NdFeB magnetic rings, reducing eddy current losses generated during the operation of high-speed magnetic levitation motors and improving their efficiency. It can also enhance the mechanical strength of thermally deformed magnets, reducing the probability of thermally deformed magnetic rings breaking during high-speed operation of magnetic levitation motors.

[0007] Furthermore, the mass ratio of MQ magnetic powder to NdFeB powder prepared by HDDR method is 0.9-1.1:1.0.

[0008] Furthermore, the particle size of the silicon carbide powder is 5 to 10 μm, and the purity is greater than 99.5%.

[0009] Another object of the present invention is to provide a method for preparing the above-mentioned thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor, comprising the following steps:

[0010] (1) MQ magnetic powder and NdFeB powder prepared by HDDR method are ground and sieved and then mixed, silicon carbide powder is added and mixed evenly, cold pressed and oriented to obtain a magnet, and hot pressed and hot deformed to obtain a hot deformed NdFeB magnetic ring;

[0011] (2) After the thermally deformed NdFeB magnetic ring is plasma activated, a terbium metal layer is magnetron sputtered on its surface and an aging treatment is performed to obtain a thermally deformed NdFeB magnetic ring for magnetic levitation high-speed motor.

[0012] A terbium metal layer is sputtered on the surface of the thermally deformed NdFeB magnetic ring. The plasma activation principle is used to fully activate the surface of the thermally deformed NdFeB magnetic ring. The activity between the NdFeB grains on the surface of the magnetic ring is increased through chemical modification, which improves the surface adhesion of the magnetic ring and promotes the entry of terbium metal atoms into the NdFeB grain boundary during the grain boundary diffusion process, thereby improving the coercive force of the thermally deformed NdFeB magnetic ring.

[0013] Furthermore, the particle size of the MQ magnetic powder and the NdFeB powder prepared by the HDDR method in step (1) after grinding and sieving is 50 to 300 μm.

[0014] Furthermore, in step (1), the cold pressing pressure is 300-500 MPa, the cold pressing time is 3-8 min, the orientation magnetic field is 0.5-2.0 T, and the orientation magnetic field direction is perpendicular to the pressure direction.

[0015] Furthermore, the pressure of the hot pressing treatment in step (1) is 200-300 MPa, the temperature is 600-750° C., the time is 3-5 min, and the vacuum degree is less than or equal to 5 MPa.

[0016] Furthermore, the pressure of the thermal deformation treatment in step (1) is 300-500 MPa, the temperature is 600-900° C., the time is 5-15 min, and the vacuum degree is less than or equal to 5 MPa.

[0017] Furthermore, during the plasma activation in step (2), the vacuum is pumped to 1.0×10 -5 ~1.0×10 -3 Pa, inert gas is the working gas, and the vacuum range of the ion source is 2~10×10 -2 Pa, anode voltage is 110-180V, anode current is 0.5-1.5A, and working time is 5-15min.

[0018] Furthermore, in step (2), DC sputtering is used during magnetron sputtering, with a DC current of 0.1 to 0.8 A, a voltage of 220 to 450 V, an inert gas as the working gas, a working pressure of 0.1 to 15.0 Pa, and a power density of 1 to 8 W / cm 2 , the sputtering time is 0.5~10.0h.

[0019] Furthermore, in step (2), the thickness of the magnetron sputtered terbium metal layer is 5 to 50 μm.

[0020] Furthermore, the aging treatment in step (2) includes primary aging treatment and secondary aging treatment, the primary aging treatment is performed at a temperature of 750-900° C. for 5-10 h, and the secondary aging treatment is performed at a temperature of 450-650° C. for 2-5 h.

[0021] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0022] (1) MQ magnetic powder prepared by traditional rapid quenching method and NdFeB powder prepared by hydrogen absorption-disproportionation-dehydrogenation-recombination method, adding silicon carbide powder and attaching terbium alloy powder on the surface, combining thermal deformation process and plasma activation treatment process, to obtain NdFeB magnetic ring with high coercivity and good thermal stability;

[0023] (2) The NdFeB powder prepared by the HDDR method has high anisotropy and high coercivity. The magnetic ring obtained by mixing it with MQ magnetic powder has high remanence and high coercivity, which effectively improves the thermal stability of the thermally deformed magnetic ring;

[0024] (3) Silicon carbide powder can effectively increase the resistivity of NdFeB magnetic rings, reduce the eddy current loss generated when the magnetic levitation high-speed motor is working, and improve its working efficiency. It can also enhance the mechanical strength of thermally deformed magnets and reduce the probability of thermally deformed magnetic rings breaking during the high-speed operation of the magnetic levitation high-speed motor.

[0025] (4) Sputtering a terbium metal layer on the surface of the thermally deformed NdFeB magnetic ring increases the activity and surface adhesion between the NdFeB grains on the surface of the magnetic ring, prompting Tb metal atoms to enter the grain boundaries, further improving the coercive force of the thermally deformed magnetic ring;

[0026] (5) The thermally deformed NdFeB magnetic ring in the technical solution of the present invention has high coercive force, high mechanical strength and good stability, and can be used in magnetic levitation high-speed motors. DETAILED DESCRIPTION

[0027] The technical scheme of the present invention is further described below by specific examples. It should be understood that the specific examples described herein are only used to help understand the present invention and are not intended to be limiting of the present invention. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0028] The MQ magnetic powder used in the following examples and comparative examples was purchased from the manufacturer; the HDDR method for preparing NdFeB powder includes the following steps:

[0029] (1) In at%, according to Nd 13 Fe 60.5 Co 14.5 B 6.4 Zr 2.6 The proportion of Zn3 is based on metal neodymium, iron, ferroboron, electrolytic cobalt, metal zirconium and metal zinc, which are smelted under argon protection and cast to obtain alloy ingots; the alloy ingots are crushed to prepare quick-setting casting sheets;

[0030] (2) Under argon protection, the rapid solidification casting was heated to 950°C at a rate of 55°C / min and heat treated for 1.5 h;

[0031] (3) After heat treatment, the heat-treated rapid solidification casting was sand-ground to remove the surface oxide layer. The hydrogen pressure was 0.3 MPa and the temperature was 200 ° C. The hydrogen absorption treatment was carried out for 2 h. Under vacuum conditions, it was heated to 750 ° C. 0.15 MPa of hydrogen was introduced. The hydrogen absorption and disproportionation was carried out for 2.5 h. The hydrogen partial pressure was reduced to 0.015 MPa. The temperature was raised to 800 ° C at 5 ° C / min, and then raised to 850 ° C at 15 ° C / min, maintained for 0.5 h, cooled to 750 ° C, and vacuumed to ≤ 10 -2 Pa was dehydrogenated for 2 h, filled with argon, and cooled to room temperature to obtain the NdFeB material prepared by the HDDR method.

[0032] Example 1

[0033] The preparation method of the thermally deformed NdFeB magnetic ring for the magnetic levitation high-speed motor of this embodiment is as follows:

[0034] (1) MQ magnetic powder and NdFeB powder prepared by HDDR method were ground and sieved into powder with particle size of 100 μm, 50 parts of each were mixed, 1.0 part of SiC powder with particle size of 5 μm was added and mixed evenly, and cold pressed for 3 min at 300 MPa for orientation, and the orientation magnetic field was 1.0 T;

[0035] (2) The cold-pressed oriented magnet was hot-pressed at 5 MPa vacuum, 200 MPa pressure, and 600°C for 5 min, and then heat-deformed at 5 MPa vacuum, 300 MPa pressure, and 600°C for 15 min to obtain a heat-deformed magnetic ring;

[0036] (3) Plasma activation is performed on the thermally deformed NdFeB magnetic ring, and vacuum is drawn to 1.0×10 -4 Pa, argon is the working gas, and the vacuum degree of the ion source is 5×10 -2 Pa, anode voltage of 150V, anode current of 1.0A, plasma activation time of 10min, a 10μm thick terbium metal layer was magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring after plasma activation, DC sputtering was adopted during magnetron sputtering, DC current of 0.2A, voltage of 250V, argon as working gas, working gas pressure of 5.0Pa, power density of 2W / cm 2 The sputtering time is 1.0h, and aging treatment is carried out. The temperature of the first aging treatment is 750℃, the time is 5h, and the temperature of the second aging treatment is 450℃, the time is 2h. After aging treatment, a hot-deformed NdFeB magnetic ring for magnetic levitation high-speed motor is obtained.

[0037] Example 2

[0038] The preparation method of the thermally deformed NdFeB magnetic ring for the magnetic levitation high-speed motor of this embodiment is as follows:

[0039] (1) MQ magnetic powder and NdFeB powder prepared by HDDR method were ground and sieved into powder with a particle size of 100 μm, 50 parts of each were mixed, 3.0 parts of SiC powder with a particle size of 5 μm were added and mixed evenly, and cold pressed for 3 min at 300 MPa for orientation, and the cold pressing magnetic field was 1.0 T;

[0040] (2) The cold-pressed oriented magnet was hot-pressed at 5 MPa vacuum, 250 MPa pressure, and 600°C for 5 min, and then heat-deformed at 5 MPa vacuum, 300 MPa pressure, and 650°C for 10 min to obtain a heat-deformed magnetic ring;

[0041] (3) Plasma activation is performed on the thermally deformed NdFeB magnetic ring, and vacuum is drawn to 1.0×10 -4 Pa, argon is the working gas, and the vacuum degree of the ion source is 5×10 -2 Pa, anode voltage of 150V, anode current of 1.0A, plasma activation time of 10min, a 10μm thick terbium metal layer was magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring after plasma activation, DC sputtering was adopted during magnetron sputtering, DC current of 0.2A, voltage of 250V, argon as working gas, working gas pressure of 5.0Pa, power density of 2W / cm 2 The sputtering time is 1.0h, and aging treatment is carried out. The temperature of the first aging treatment is 750℃, the time is 8h, and the temperature of the second aging treatment is 450℃, the time is 3h. After aging treatment, a hot-deformed NdFeB magnetic ring for magnetic levitation high-speed motor is obtained.

[0042] Example 3

[0043] The preparation method of the thermally deformed NdFeB magnetic ring for the magnetic levitation high-speed motor of this embodiment is as follows:

[0044] (1) MQ magnetic powder and NdFeB powder prepared by HDDR method were ground and sieved into powder with a particle size of 150 μm, 45 parts and 55 parts of them were mixed respectively, 3.0 parts of 5 μm silicon carbide powder were added and mixed evenly, and cold pressed for 5 min at 400 MPa for orientation, and the cold pressing magnetic field was 1.0 T;

[0045] (2) The cold-pressed oriented magnet was hot-pressed at 3 MPa vacuum, 200 MPa pressure, and 600°C for 4 min, and then heat-deformed at 3 MPa vacuum, 400 MPa pressure, and 700°C for 10 min to obtain a heat-deformed magnetic ring;

[0046] (3) Plasma activation is performed on the thermally deformed NdFeB magnetic ring, and vacuum is drawn to 1.0×10 -4 Pa, argon is the working gas, and the vacuum degree of the ion source is 5×10 -2 Pa, anode voltage of 150V, anode current of 1.0A, plasma activation time of 10min, a terbium metal layer with a thickness of 30μm was magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring after plasma activation. DC sputtering was used during magnetron sputtering, with a DC current of 0.2A, a voltage of 250V, argon as the working gas, a working gas pressure of 5.0Pa, and a power density of 2W / cm 2 The sputtering time is 1.0h, and aging treatment is carried out. The temperature of the first aging treatment is 800℃, the time is 5h, and the temperature of the second aging treatment is 500℃, the time is 2h. After aging treatment, a hot-deformed NdFeB magnetic ring for magnetic levitation high-speed motor is obtained.

[0047] Example 4

[0048] The preparation method of the thermally deformed NdFeB magnetic ring for the magnetic levitation high-speed motor of this embodiment is as follows:

[0049] (1) MQ magnetic powder and NdFeB powder prepared by HDDR method were ground and sieved into powder with a particle size of 200 μm, 50 parts of each were mixed, 5.0 parts of 5 μm silicon carbide powder were added and mixed evenly, and cold pressed for 6 min at 500 MPa for orientation, and the cold pressing magnetic field was 1.0 T;

[0050] (2) The cold-pressed oriented magnet was hot-pressed at 5 MPa vacuum, 200 MPa pressure, and 650°C for 4 min, and then heat-deformed at 5 MPa vacuum, 350 MPa pressure, and 800°C for 8 min to obtain a heat-deformed magnetic ring;

[0051] (3) Plasma activation is performed on the thermally deformed NdFeB magnetic ring, and vacuum is drawn to 1.0×10 -4 Pa, argon is the working gas, and the vacuum degree of the ion source is 5×10 -2 Pa, anode voltage of 150V, anode current of 1.0A, plasma activation time of 10min, a 10μm thick terbium metal layer was magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring after plasma activation, DC sputtering was adopted during magnetron sputtering, DC current of 0.2A, voltage of 250V, argon as working gas, working gas pressure of 5.0Pa, power density of 2W / cm 2 The sputtering time is 1.0h, and aging treatment is carried out. The temperature of the first aging treatment is 750℃, the time is 10h, and the temperature of the second aging treatment is 450℃, the time is 5h. After aging treatment, a hot-deformed NdFeB magnetic ring for magnetic levitation high-speed motor is obtained.

[0052] Example 5

[0053] The preparation method of the thermally deformed NdFeB magnetic ring for the magnetic levitation high-speed motor of this embodiment is as follows:

[0054] (1) MQ magnetic powder and NdFeB powder prepared by HDDR method were ground and sieved into powder with a particle size of 300 μm, 50 parts and 55 parts of them were mixed respectively, 2.0 parts of 5 μm silicon carbide powder were added and mixed evenly, and cold pressed for 8 min at 500 MPa for orientation, and the cold pressing magnetic field was 1.0 T;

[0055] (2) The cold-pressed oriented magnet was hot-pressed at 4 MPa vacuum, 300 MPa pressure, and 700°C for 3 min, and then heat-deformed at 4 MPa vacuum, 300 MPa pressure, and 7900°C for 5 min to obtain a heat-deformed magnetic ring;

[0056] (3) Plasma activation is performed on the thermally deformed NdFeB magnetic ring, and vacuum is drawn to 1.0×10 -4 Pa, argon is the working gas, and the vacuum degree of the ion source is 5×10 -2 Pa, anode voltage of 150V, anode current of 1.0A, plasma activation time of 10min, a 50μm thick terbium metal layer was magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring after plasma activation, DC sputtering was adopted during magnetron sputtering, DC current was 0.2A, voltage was 250V, argon was used as the working gas, working gas pressure was 5.0Pa, power density was 2W / cm 2 The sputtering time is 1.0h, and aging treatment is carried out. The temperature of the first aging treatment is 850℃ and the time is 8h. The temperature of the second aging treatment is 550℃ and the time is 4h. After aging treatment, a hot-deformed NdFeB magnetic ring for magnetic levitation high-speed motor is obtained.

[0057] Example 6

[0058] The only difference between this embodiment and embodiment 1 is that in step (3), the thickness of the terbium metal layer magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring is 3 μm.

[0059] Example 7

[0060] The only difference between this embodiment and embodiment 1 is that in step (3), the thickness of the terbium metal layer magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring is 60 μm.

[0061] Comparative Example 1

[0062] The only difference between this comparative example and Example 1 is that step (1) is to grind and sieve the MQ magnetic powder and the NdFeB powder prepared by the HDDR method into powders with a particle size of 100 μm, respectively, take 35 parts and 65 parts of them respectively, mix them, add 1.0 part of silicon carbide powder with a particle size of 5 μm, and mix them evenly. Cold pressing orientation is carried out at 300 MPa for 3 minutes, and the cold pressing magnetic field is 1.0 T.

[0063] Comparative Example 2

[0064] The only difference between this comparative example and Example 1 is that step (1) is to grind and sieve the MQ magnetic powder and the NdFeB powder prepared by the HDDR method into powders with a particle size of 100 μm, respectively, take 60 parts and 40 parts of them respectively, mix them, add 1.0 part of silicon carbide powder with a particle size of 5 μm, and mix them evenly. Cold pressing orientation is carried out at 300 MPa for 3 minutes, and the cold pressing magnetic field is 1.0 T.

[0065] Comparative Example 3

[0066] The only difference between this comparative example and Example 1 is that step (1) is to grind and sieve the MQ magnetic powder and the NdFeB powder prepared by the HDDR method into powders with a particle size of 100 μm, take 50 parts of each and mix them, add 0.1 parts of silicon carbide powder with a particle size of 5 μm and mix them evenly, and cold press orientation is carried out at 300 MPa for 3 minutes, and the cold pressing magnetic field is 1.0 T.

[0067] Comparative Example 4

[0068] The only difference between this comparative example and Example 1 is that step (1) is to grind and sieve the MQ magnetic powder and the NdFeB powder prepared by the HDDR method into powders with a particle size of 100 μm, take 50 parts of each and mix them, add 6.0 parts of silicon carbide powder with a particle size of 5 μm and mix them evenly, and cold press orientation is carried out at 300 MPa for 3 minutes, and the cold pressing magnetic field is 1.0 T.

[0069] Comparative Example 5

[0070] The preparation method of the thermally deformed NdFeB magnetic ring of this comparative example is as follows:

[0071] (1) After grinding and sieving MQ magnetic powder to a powder with a particle size of 100 μm, 100 parts of the sieved MQ magnetic powder were added to 1.0 part of silicon carbide powder with a particle size of 5 μm, mixed evenly, and cold pressed at 300 MPa for 3 minutes for cold pressing orientation;

[0072] (2) The cold-pressed oriented magnet was hot-pressed at 5 MPa vacuum, 200 MPa pressure, and 600°C for 5 min, and then heat-deformed at 5 MPa vacuum, 300 MPa pressure, and 600°C for 15 min to obtain a heat-deformed magnetic ring;

[0073] (3) Plasma activation is performed on the thermally deformed NdFeB magnetic ring, and vacuum is drawn to 1.0×10 -4 Pa, argon is the working gas, and the vacuum degree of the ion source is 5×10 -2 Pa, anode voltage of 150V, anode current of 1.0A, plasma activation time of 10min, a 10μm thick terbium metal layer was magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring after plasma activation, DC sputtering was adopted during magnetron sputtering, DC current of 0.2A, voltage of 250V, argon as working gas, working gas pressure of 5.0Pa, power density of 2W / cm 2 The sputtering time is 1.0h, and aging treatment is carried out. The temperature of the first aging treatment is 750℃, the time is 5h, and the temperature of the second aging treatment is 450℃, the time is 2h. After aging treatment, a hot-deformed NdFeB magnetic ring for magnetic levitation high-speed motor is obtained.

[0074] Comparative Example 6

[0075] The preparation method of the thermally deformed NdFeB magnetic ring of this comparative example is as follows:

[0076] (1) The NdFeB powder prepared by the HDDR method was ground and sieved to a powder with a particle size of 100 μm. Then, 50 parts of the sieved NdFeB powder prepared by the HDDR method were taken, 1.0 part of 5 μm silicon carbide powder was added and mixed evenly. The mixture was then cold pressed at 300 MPa for 3 minutes for cold press orientation, and the orientation magnetic field was 1.0 T.

[0077] (2) The cold-pressed oriented magnet was hot-pressed at 5 MPa vacuum, 200 MPa pressure, and 600°C for 5 min, and then heat-deformed at 5 MPa vacuum, 300 MPa pressure, and 600°C for 15 min to obtain a heat-deformed magnetic ring;

[0078] (3) A 10 μm thick terbium metal layer is magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring, and aging treatment is performed. The temperature of the first aging treatment is 750°C and the time is 5 h. The temperature of the second aging treatment is 450°C and the time is 2 h. After aging treatment, a thermally deformed NdFeB magnetic ring for magnetic levitation high-speed motor is obtained.

[0079] Comparative Example 7

[0080] The preparation method of the thermally deformed NdFeB magnetic ring of this comparative example is as follows:

[0081] (1) 50 parts of MQ magnetic powder and 50 parts of NdFeB powder were ground and sieved to a powder with a particle size of 100 μm, then mixed and cold pressed at 300 MPa for 3 min for cold press orientation;

[0082] (2) The cold-pressed oriented magnet was hot-pressed at 5 MPa vacuum, 200 MPa pressure, and 600°C for 5 min, and then heat-deformed at 5 MPa vacuum, 300 MPa pressure, and 600°C for 15 min to obtain a heat-deformed magnetic ring;

[0083] (3) A 10 μm thick terbium metal layer is magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring, and aging treatment is performed. The temperature of the first aging treatment is 750°C and the time is 5 h. The temperature of the second aging treatment is 450°C and the time is 2 h. After aging treatment, a thermally deformed NdFeB magnetic ring for magnetic levitation high-speed motor is obtained.

[0084] Comparative Example 8

[0085] The preparation method of the thermally deformed NdFeB magnetic ring of this comparative example is as follows:

[0086] (1) 50 parts of MQ magnetic powder and 50 parts of NdFeB powder were ground and sieved into powder with a particle size of 100 μm, and then mixed. 1.0 part of silicon carbide powder with a particle size of 5 μm was added and mixed evenly. Cold pressing was performed at 300 MPa for 3 minutes for cold pressing orientation.

[0087] (2) The cold-pressed oriented magnet was hot-pressed at 5 MPa vacuum, 200 MPa pressure, and 600°C for 5 min, and then heat-deformed at 5 MPa vacuum, 300 MPa pressure, and 600°C for 15 min to obtain a heat-deformed magnetic ring;

[0088] (3) Aging treatment: the temperature of the first aging treatment is 750℃ and the time is 5h; the temperature of the second aging treatment is 450℃ and the time is 2h. After aging treatment, the thermally deformed NdFeB magnetic ring for magnetic levitation high-speed motor is obtained.

[0089] Comparative Example 9

[0090] The preparation method of the thermally deformed NdFeB magnetic ring of this comparative example is as follows:

[0091] (1) MQ magnetic powder and NdFeB powder prepared by HDDR method were ground and sieved into powder with particle size of 100 μm, 50 parts of each were mixed, 1.0 part of SiC powder with particle size of 5 μm was added and mixed evenly, and cold pressed for 3 min at 300 MPa for orientation, and the orientation magnetic field was 1.0 T;

[0092] (2) The cold-pressed oriented magnet was hot-pressed at 5 MPa vacuum, 200 MPa pressure, and 600°C for 5 min, and then heat-deformed at 5 MPa vacuum, 300 MPa pressure, and 600°C for 15 min to obtain a heat-deformed magnetic ring;

[0093] (3) A 10 μm thick terbium metal layer was magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring. DC sputtering was used during magnetron sputtering. The DC current was 0.2 A, the voltage was 250 V, argon was used as the working gas, the working pressure was 5.0 Pa, and the power density was 2 W / cm 2 The sputtering time is 1.0h, and aging treatment is carried out. The temperature of the first aging treatment is 750℃, the time is 5h, and the temperature of the second aging treatment is 450℃, the time is 2h. After aging treatment, a hot-deformed NdFeB magnetic ring for magnetic levitation high-speed motor is obtained.

[0094] The magnetic properties of the thermally deformed NdFeB magnetic rings prepared in the above examples and comparative examples were tested, and the performance test results are shown in Table 1.

[0095] Table 1 Magnetic properties test results of NdFeB magnetic ring

[0096]

[0097]

[0098] The NdFeB magnetic rings obtained in Examples 1-5 have high coercivity and good thermal stability. In Example 6, too little terbium metal layer is magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring, and too few terbium metal atoms enter the magnetic ring during the subsequent grain boundary diffusion process, resulting in a low increase in the coercivity of the magnetic ring; in Example 7, too much terbium metal layer is magnetron sputtered on the surface of the thermally deformed NdFeB magnetic ring. The excessive number of terbium metal atoms entering the magnetic ring will greatly increase its coercivity, but the remanence of the magnetic ring will decrease; in Comparative Example 1, too much NdFeB powder prepared by the HDDR method is used, and the coercivity is increased, but the contribution of the HDDR anisotropic powder to the remanence during the deformation process is slightly lower, resulting in a decrease in the remanence; in Comparative Example 2, too much MQ magnetic powder is used, which can increase the remanence, but the coercivity decreases with the increase of MQ magnetic powder; in Comparative Example 3, too little silicon carbide powder is added, resulting in a small increase in the coercivity of the magnetic ring , resulting in a decrease in resistivity and mechanical strength; in Comparative Example 4, adding too much silicon carbide powder will increase the coercive force, resistivity and mechanical strength of the magnetic ring, but the increase in non-magnetic material will cause the remanence of the magnetic ring to be significantly lower; in Comparative Example 5, NdFeB powder prepared by the HDDR method is not added. Since the MQ magnetic powder grains are small and easily thermally deformed, the remanence is increased, but the coercive force of the magnetic ring is reduced; in Comparative Example 6, MQ magnetic powder is not added, the remanence of the magnetic ring is slightly lower, but the high coercive force of the HDDR magnetic powder is maintained; in Comparative Example 7, silicon carbide powder is not added, the coercive force of the magnetic ring is slightly increased, and the resistivity and mechanical strength are not increased; in Comparative Example 8, terbium alloy powder is not added, and no terbium atoms enter the grain boundaries, and the coercive force of the magnetic ring will not be increased; in Comparative Example 9, plasma activation is not performed, the surface of the magnetic ring is not effectively activated, and the terbium atoms fail to enter the grain boundaries well, resulting in poor coercive force improvement effect of the magnetic ring.

[0099] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the spirit of the present invention and are not intended to limit the manner in which the present invention is intended to be implemented. Persons skilled in the art may make various modifications, additions, or substitutions to the described embodiments, and it is not necessary or possible to provide a comprehensive list of all possible embodiments. However, any obvious changes or modifications arising from the essential spirit of the present invention remain within the scope of protection of the present invention, and interpreting them as any additional limitations would be contrary to the spirit of the present invention.

Claims

1. A thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor, characterized in that: The invention comprises a NdFeB magnetic ring body and a terbium metal layer arranged on the surface of the NdFeB magnetic ring body. The raw materials of the NdFeB magnetic ring body include the following components in mass percentage: 40.0-50.0% MQ magnetic powder, 45.0-55.0% NdFeB powder prepared by HDDR method and 0.5-5.0% silicon carbide powder. The method for preparing the thermally deformed NdFeB magnetic ring for the magnetic levitation high-speed motor comprises the following steps: (1) MQ magnetic powder and NdFeB powder prepared by HDDR method are ground and sieved and then mixed, silicon carbide powder is added and mixed evenly, cold pressed and oriented to obtain a magnet, and hot pressed and hot deformed to obtain a hot deformed NdFeB magnetic ring; (2) After the thermally deformed NdFeB magnetic ring is plasma activated, a terbium metal layer is magnetron sputtered on its surface, and an aging treatment is performed to obtain a thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor; The thickness of the magnetron sputtered terbium metal layer in step (2) is 5 to 50 μm.

2. The thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor according to claim 1, characterized in that: The mass ratio of MQ magnetic powder to NdFeB powder prepared by HDDR method is 0.9-1.1:1.

0.

3. The thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor according to claim 1, characterized in that: The particle size of the silicon carbide powder is 5 to 10 μm, and the purity is greater than 99.5%.

4. The thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor according to claim 1, characterized in that: The particle size of the MQ magnetic powder and the NdFeB powder prepared by the HDDR method in step (1) after grinding and sieving is 50 to 300 μm.

5. The thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor according to claim 1, characterized in that: In step (1), the cold pressing pressure is 300-500 MPa, the cold pressing time is 3-8 min, and the orientation magnetic field is 0.5-2.0 T.

6. The thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor according to claim 1, characterized in that: The pressure of the hot pressing treatment in step (2) is 200-300 MPa, the temperature is 600-750° C., the time is 3-5 min, and the vacuum degree is less than or equal to 5 MPa.

7. The thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor according to claim 1, characterized in that: The pressure of the thermal deformation treatment in step (2) is 300-500 MPa, the temperature is 600-900° C., the time is 5-15 min, and the vacuum degree is less than or equal to 5 MPa.

8. The thermally deformed NdFeB magnetic ring for a magnetic levitation high-speed motor according to claim 1, characterized in that: The aging treatment in step (3) includes primary aging treatment and secondary aging treatment. The temperature of the primary aging treatment is 750-900° C. and the time is 5-10 hours. The temperature of the secondary aging treatment is 450-650° C. and the time is 2-5 hours.

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