Neodymium-iron-boron magnets and methods of making and using the same

Abstract

The present application relates to a kind of neodymium-iron-boron magnet and its preparation method and application.Neodymium-iron-boron magnet includes non-easy demagnetization area, transition area and easy demagnetization area.The preparation method of neodymium-iron-boron magnet includes the following steps: on neodymium-iron-boron base material, respectively on the upper surface and / or lower surface perpendicular to Z axis direction diffusion source is applied, the grain boundary diffusion parallel to orientation direction is carried out;Wherein, diffusion source Dy is applied on the upper surface and lower surface entire area, diffusion source Tb is applied on the outer edge annular area along Z axis direction, easy demagnetization area, transition area and non-easy demagnetization area are formed.The neodymium-iron-boron magnet of the present application can reduce the attenuation of neodymium-iron-boron magnet surface magnetic and magnetic flux under the premise of guaranteeing residual magnetism, and the anti-demagnetization performance is good.

Description

TECHNICAL FIELD

[0001] The present application relates to a neodymium-iron-boron magnet and a preparation method and application thereof. BACKGROUND

[0002] Since the advent of neodymium-iron-boron permanent magnet, it has been widely used in the fields of automobile, wind power, household appliances, industrial robots, etc. Due to different working conditions in different fields, the performance of the magnetic steel product in the field is also required to be different. In recent years, new energy vehicles have developed rapidly, and the demand for magnetic steel of main drive motor has increased sharply. Since the normal working temperature of the main drive motor mainly concentrates in the range of 120-180℃, the neodymium-iron-boron needs higher coercivity and thermal stability. In order to improve the temperature resistance of rare earth permanent magnet, a large amount of heavy rare earth Dy and Tb is usually added to increase the anisotropic field of the main phase magnetic crystal. However, the heavy rare earth resources are scarce and the price is high, which seriously restricts the application of neodymium-iron-boron magnet in various industries.

[0003] With the increasing demand for high-performance magnets, the grain boundary diffusion technology has gradually been known and accepted by everyone. The conventional grain boundary diffusion technology adopts a physical vapor deposition method to deposit the diffusion source on the surface of the magnet, and then penetrates the diffusion source into the magnet along the grain boundary under high temperature and certain pressure. The biggest advantage of this technology is that it can greatly improve the coercivity using a small amount of heavy rare earth without changing the remanence. In terms of effective utilization of heavy rare earth, the traditional grain boundary diffusion product has been greatly improved compared with the non-grain boundary diffusion product.

[0004] However, in the actual use of neodymium-iron-boron, the performance requirements of each part of the magnet are not the same. For example, in the motor, since the reverse magnetic field generated after the coil is energized in the motor is not a uniform magnetic field, how to design a neodymium-iron-boron magnet according to the needs of different regions to meet the needs of different applications while ensuring the coercivity and remanence, and also having good anti-demagnetization ability. SUMMARY

[0005] In order to solve the defects in the prior art, the present application provides a neodymium-iron-boron magnet and a preparation method and application thereof. The neodymium-iron-boron magnet of the present application can reduce the decay of surface magnetic and magnetic flux of the neodymium-iron-boron magnet while ensuring the remanence, and has good anti-demagnetization performance.

[0006] In a first aspect, the present application provides a neodymium-iron-boron magnet, a three-dimensional rectangular coordinate system is established, and the orientation direction is the Z-axis direction. The origin of the three-dimensional rectangular coordinate system is located in the neodymium-iron-boron magnet.

[0007] The Nd-Fe-B magnet comprises a non-remanence easy region, a transition region and a remanence easy region; the remanence easy region is an outer edge annular region on the Nd-Fe-B magnet along the Z-axis direction, and the non-remanence easy region is a central region on the Nd-Fe-B magnet along the Z-axis direction; the transition region is a boundary region between the remanence easy region and the non-remanence easy region.

[0008] The content ratio of Tb in the non-remanence easy region, the transition region and the remanence easy region is (0-0.05):(0.95-1):1.

[0009] The content ratio of Dy in the non-remanence easy region, the transition region and the remanence easy region is 1:1:1.

[0010] In the present application, the central axis of the outer edge annular region is parallel to the Z-axis.

[0011] Regarding the parameters

[0012] In the present application, preferably, the content of heavy rare earth at each position in the remanence easy region is the same.

[0013] In the present application, preferably, the diffusion increment of heavy rare earth at the same X-Y position in the transition region along the Z-axis direction is the same. Preferably, the diffusion content of Tb in the transition region along the X-axis or Y-axis and away from the direction of the remanence easy region decreases.

[0014] In the present application, preferably, the content of Tb at any two same X-Y positions in the remanence easy region is the same.

[0015] In the present application, preferably, the content of Dy at any two positions in the remanence easy region, the transition region and the non-remanence easy region is the same.

[0016] In the present application, the meaning of the diffusion increment of heavy rare earth is that the mass of Tb introduced into a region by diffusion accounts for the percentage of the total mass of the magnet in the region. Specifically, the meaning of the diffusion increment of Tb is that the mass of Tb introduced into a region by diffusion accounts for the percentage of the total mass of the magnet in the region; the meaning of the diffusion increment of Dy is that the mass of Dy introduced into a region by diffusion accounts for the percentage of the total mass of the magnet in the region.

[0017] In the present application, the "the diffusion increment of heavy rare earth is the same" means that the type of heavy rare earth introduced by diffusion at each position in a region is the same, and the diffusion increment of each type of heavy rare earth is the same. Specifically, the diffusion increment of Tb is the same means that the diffusion increment of Tb introduced by diffusion is the same; the diffusion increment of Dy is the same means that the diffusion increment of Dy introduced by diffusion is the same.

[0018] In the present application, the content ratio of Tb in the transition zone to the Tb in the easy demagnetization zone can be 0.8:1 or 0.9:1.

[0019] In the present application, the content ratio of Tb in the transition zone to the Tb in the non-easy demagnetization zone can be 1:(0-0.1), preferably 1:(0-0.05).

[0020] In the present application, the content ratio of Tb in the non-easy demagnetization zone to the Tb in the easy demagnetization zone can be (0-0.9):1, for example 0.1:1, 0.2:1 or 0.7:1.

[0021] In the present application, the ratio of the diffusion increment of Tb in the easy demagnetization zone to the diffusion increment of Tb in the non-easy demagnetization zone can be (1-100):1, for example 9:1, 36:1 or 55:1.

[0022] In the present application, the ratio of the diffusion increment of Tb in the easy demagnetization zone to the diffusion increment of Tb in the transition zone can be (1-1.1):1, for example 1:1, 36:34 or 55:52.

[0023] In the present application, the diffusion increment of Tb in the easy demagnetization zone can be 0.1wt%-1wt%, for example 0.35wt%, 0.36wt%, 0.45wt% or 0.55wt%.

[0024] In the present application, the diffusion increment of Tb in the non-easy demagnetization zone can be 0-0.1wt%, preferably 0-0.05wt%, for example 0, 0.01wt% or 0.05wt%.

[0025] In the present application, the diffusion increment of Tb in the transition zone can be 0.1wt%-1wt%, for example 0.34wt%, 0.45wt% or 0.52wt%.

[0026] In the present application, the diffusion increment of Dy in the easy demagnetization zone can be 0.1wt%-1wt%, for example 0.55wt%.

[0027] In the present application, the diffusion increment of Dy in the non-easy demagnetization zone can be 0.1wt%-1wt%, preferably 0.4wt%-0.7wt%, for example 0.55wt%.

[0028] In the present application, the diffusion increment of Dy in the transition zone can be 0.1wt%-1wt%, for example 0.55wt%.

[0029] In the present application, there is an interface A between the transition zone and the easy demagnetization zone, and the content of heavy rare earth at each position of the interface A is the same.

[0030] The diffusion increment of Tb at the interface A can be 0.3wt%-0.7wt%, for example 0.36wt%, 0.45wt% or 0.55wt%.

[0031] The diffusion increment ratio of Tb at the interface A to the easy demagnetization area is preferably (0.95-1):1.

[0032] The diffusion increment of Dy at the interface A can be 0.4wt%-0.7wt%, for example 0.55wt%.

[0033] In the present application, there is an interface B between the transition area and the non-easy demagnetization area, and the heavy rare earth content at each position of the interface B is the same.

[0034] The diffusion increment of Tb at the interface B can be 0.3wt%-0.7wt%, for example 0.34wt%, 0.43wt% or 0.52wt%.

[0035] The diffusion increment ratio of Tb at the interface B to the non-easy demagnetization area is preferably (6-60):1, for example 43:5, 34:1 or 52:1.

[0036] The diffusion increment of Dy at the interface B can be 0.4wt%-0.7wt%, for example 0.55wt%.

[0037] In the present application, the coercivity ratio of the easy demagnetization area to the non-easy demagnetization area can be 1:(0.7-0.96), for example 1:0.876, 1:0.909 or 1:0.957.

[0038] In the present application, the coercivity ratio of the easy demagnetization area to the transition area can be 1:(0.93-1), for example 1:0.930, 1:0.959 or 1:0.970.

[0039] In the present application, the coercivity at each position of the easy demagnetization area can be the same.

[0040] In the present application, the coercivity at each position of the transition area along the Z-axis direction can be the same. Preferably, the coercivity in the transition area along the X-axis or Y-axis and away from the easy demagnetization area direction decreases.

[0041] In the present application, the remanence at each position of the easy demagnetization area can be the same.

[0042] In the present application, the remanence at each position of the transition area along the Z-axis direction can be the same. Preferably, the remanence in the transition area along the X-axis or Y-axis and away from the easy demagnetization area direction decreases.

[0043] Regarding the composition

[0044] In the present application, the Nd-Fe-B magnet can be represented by the formula R1-R2-T-B-M, wherein R1 can be one or more of Pr, Nd, Ce, Er, Tm, Y, Lu, Gd and Ho; R2 can be Dy and / or Tb; T can be one or more of Fe, Zn, Si, V, Cr, Mn, Ni, Ge, Nb, Mo, Pd, Ag, Cd, Sb, Hf, Ta, W, O, C, N, S, F and P; and M can be one or more of Cu, Al, Co, Ga, Zr and Ti.

[0045] In some embodiments of the present application, the M element is entirely from the Nd-Fe-B base material.

[0046] In some embodiments of the present application, the M element comprises a diffusion-introduced M element, wherein the diffusion-introduced M element preferably accounts for 0-0.4% of the mass percentage of the Nd-Fe-B magnet.

[0047] In some embodiments of the present application, the microstructure of the Nd-Fe-B magnet comprises Re2Fe 14 B main phase grains and Re-rich phase grain boundaries; the Re2Fe 14 B main phase grains comprise a core layer and a shell layer; and the Re is one or more of Nd, Dy and Tb.

[0048]

Re2Fe 14 B main phase grains

[0049] wherein the Re2Fe 14 B main phase grains in the easy demagnetization zone have a difference in particle size of no more than 8 μm.

[0050] wherein the Re2Fe 14 B main phase grains in the transition zone have a difference in particle size of no more than 8 μm.

[0051] wherein the Re2Fe 14 B main phase grains in the surface layer of the easy demagnetization zone, the transition zone and the non-easy demagnetization zone are equal in size, wherein the surface layer means a surface perpendicular to the orientation direction.

[0052] wherein the Re2Fe 14 B main phase grains in the center of the easy demagnetization zone, the transition zone and the non-easy demagnetization zone are equal in size, wherein the center means a median plane along the orientation direction.

[0053] In some specific embodiments of the present application, the Re2Fe 14The size of the B main phase grains is preferably 1-1.5 times the size of the central main phase grains.

[0054] In a specific embodiment of the application, the Re2Fe 14 The size of the B main phase grains is preferably 1-1.5 times the size of the central main phase grains.

[0055] In a specific embodiment of the application, the Re2Fe 14 The size of the B main phase grains is preferably 1-1.5 times the size of the central main phase grains.

[0056] In the above, the size of the grains refers to the average size of all the grains in a region. For example, the Re2Fe 14 The size of the B main phase grains is preferably 1-1.5 times the size of the central main phase grains. 14 The size of the B main phase grains is preferably 1-1.5 times the size of the central main phase grains.

[0057]

Re-rich grain boundary

[0058] In the present application, the Re-rich grain boundary has its conventional meaning in the art, i.e. a grain boundary region with Re > 95%.

[0059] The thickness of the Re-rich grain boundary in the soft magnetic region can be equal, i.e. the thickness of the Re-rich grain boundary in each region of the soft magnetic region is kept constant.

[0060] The thickness of the Re-rich grain boundary in the soft magnetic region can be equal, i.e. the thickness of the Re-rich grain boundary in each region of the soft magnetic region is kept constant.

[0061] In a specific embodiment of the application, the thickness of the Re-rich grain boundary in the soft magnetic region is 0.4-1 μm, such as 0.5 μm or 0.55 μm.

[0062] In a specific embodiment of the application, the thickness of the Re-rich grain boundary in the soft magnetic region is 0.4-1 μm, such as 0.5 μm or 0.55 μm.

[0063] In a specific embodiment of the application, the thickness of the Re-rich grain boundary in the soft magnetic region is 0.4-1 μm, such as 0.5 μm or 0.55 μm.

[0064]

Core layer and shell layer

[0065] In a specific embodiment of the application, the shell layer is a Re2Fe 14 B hard magnetic layer.

[0066] In some embodiments of the application, the shell of the soft magnetic region is (Nd, Dy, Tb)2Fe 14 B hard magnetic layer.

[0067] In some embodiments of the application, the shell of the non-soft magnetic region is (Nd, Dy)2Fe 14 B hard magnetic layer.

[0068] wherein the core and shell in the soft magnetic region, the transition region and the non-soft magnetic region can each independently satisfy the following conditions: the content of R1 in the core is not less than the content of R1 in the shell; the content of R2 in the core is less than the content of R2 in the shell.

[0069] wherein the R2 is Tb, and the content of R2 in the soft magnetic region, the transition region and the non-soft magnetic region can satisfy the following conditions: soft magnetic region > transition region > non-soft magnetic region.

[0070] wherein the R2 is Dy, and the content of R2 in the soft magnetic region, the transition region and the non-soft magnetic region can satisfy the following conditions: non-soft magnetic region = transition region = soft magnetic region.

[0071] wherein the thickness of the shell of the soft magnetic region can be equal, i.e. the thickness of the shell of each region in the soft magnetic region remains unchanged.

[0072] wherein the thickness of the shell of the transition region can be equal, i.e. the thickness of the shell of each region in the transition region remains unchanged.

[0073] In some specific embodiments of the application, the thickness of the shell of the soft magnetic region is 2-3 μm, for example 2 μm, 2.1 μm or 2.5 μm.

[0074] In some specific embodiments of the application, the thickness of the shell of the main phase grain of the transition region is 2-2.5 μm, for example 2 μm or 2.38 μm.

[0075] In some specific embodiments of the application, the thickness of the shell of the main phase grain of the non-soft magnetic region is 0.5-2 μm, for example 0.95 μm, 1.0 μm or 1.1 μm.

[0076] In some specific embodiments of the application, the thickness of the shell of the soft magnetic region and the Re-rich phase grain boundary is preferably (2-3):(0.4-1), for example 4:1, 2.1:0.5 or 2.5:0.55.

[0077] In some specific embodiments of the application, the thickness of the shell of the transition region and the Re-rich phase grain boundary is preferably (2-2.5):(0.4-1), for example 4:1 or 2.38:0.52.

[0078] In some embodiments of the present application, the thickness of the shell of the main phase grains of the non-remanence easy region and the Re-rich phase grain boundary is preferably (0.5-2):(0.2-0.5), for example 1.1:0.25, 1.0:0.23 or 0.95:0.20.

[0079] Regarding the structure

[0080] In the present application, the neodymium-iron-boron magnet can be a cuboid. The origin can be located at the center of the upper surface of the cuboid. The X axis of the three-dimensional rectangular coordinate system can be parallel to one side of the upper surface.

[0081] In the present application, the specific position of the upper surface is not specifically limited, and those skilled in the art can generally understand that the upper surface refers to the surface opposite to the plane when the magnet is placed on the plane.

[0082] In the present application, the ratio of the length to the width of the neodymium-iron-boron magnet is (2-5):1, preferably (2.42-3.7):1, for example 3:1, 3.65:1 or 39:10.7, the length refers to the extension distance of one side of the upper surface along the positive direction of the X axis, and the width refers to the extension distance of the cuboid from the upper surface along the positive direction of the Y axis.

[0083] In the present application, the width of the non-remanence easy region can be equal, that is, the distance of the non-remanence easy region extending from the edge of the neodymium-iron-boron magnet along the X axis or the Y axis is constant.

[0084] Preferably, the width of the non-remanence easy region is not greater than 5 mm, for example 2-4 mm.

[0085] In the present application, on any plane perpendicular to the orientation direction, the shape of the non-remanence easy region can be elliptical.

[0086] In the present application, the ratio of the major axis a to the minor axis b of the non-remanence easy region can be (2-15):1, for example 17.5:3.35.

[0087] In the present application, the width of the transition region can be equal, that is, the distance of the transition region extending from the edge of the neodymium-iron-boron magnet along the X axis or the Y axis is constant.

[0088] Preferably, the width of the transition region is 0-2 mm, not 0, for example 0.5 mm.

[0089] In the present application, the volume percentage of the non-remanence easy region in the volume of the neodymium-iron-boron magnet can be 40%-90%, for example 47.85%.

[0090] In the present application, the volume percentage of the transition zone in the volume of the Nd-Fe-B magnet can be 0-28.4%, for example, 8.04%.

[0091] In the present application, the volume percentage of the non-reversible demagnetization zone in the volume of the Nd-Fe-B magnet can be 15.7%-44.11%.

[0092] In the present application, the non-reversible demagnetization zone, the transition zone and the reversible demagnetization zone can be obtained by simulating a cloud picture under working conditions.

[0093] In the present application, the thickness of the Nd-Fe-B magnet can be not more than 5mm, for example, 3mm.

[0094] In a second aspect, the present application also provides a preparation method of a Nd-Fe-B magnet, which comprises the following steps: applying diffusion sources on the upper surface and / or the lower surface perpendicular to the Z-axis direction of a Nd-Fe-B substrate, and performing grain boundary diffusion parallel to the orientation direction; wherein, diffusion source Dy is applied on the entire area of the upper surface and the lower surface, and diffusion source Tb is applied on the annular area along the outer edge in the Z-axis direction, to form the reversible demagnetization zone, the transition zone and the non-reversible demagnetization zone.

[0095] In the present application, it is known to those skilled in the art that when performing grain boundary diffusion, the Dy or Tb in the diffusion source does not completely diffuse into the magnet, and the utilization rate is generally 85%-95%, so in the actual preparation process, a larger amount of Dy or Tb is generally applied.

[0096] In the present application, it is known to those skilled in the art that different grain boundary diffusion methods will have different coating thicknesses when diffusing the same amount of Dy or Tb into the magnet, so in the actual preparation process, the coating thickness is not limited, as long as the corresponding diffusion amount of Dy or Tb is achieved.

[0097] In the present application, the application method of the diffusion source can be performed by conventional methods in the art, for example, coating.

[0098] Preferably, the coating method is spraying or printing. The dewaxing temperature of the spraying can be 200-400℃. The dewaxing temperature of the printing can be 100-500℃.

[0099] In the present application, when the diffusion source is applied by coating, the diffusion source is generally mixed with a solvent and a binder in a certain proportion to form a slurry. The solvent can be water, alcohol, ketone or ester. The mass percentage of Dy or Tb in the diffusion source in the slurry can be 0.3%-1%.

[0100] In the present application, the diffusion source Dy can be Dy element.

[0101] In the present application, the diffusion source Dy can be a Dy-M alloy, and M can be one or more of Cu, Al, Co, Ga, Zr and Ti. In this case, the mass percentage of M in the Dy-M alloy can be no more than 40%.

[0102] In the present application, the diffusion source Dy can be a hydride of Dy or a fluoride of Dy.

[0103] In the present application, the diffusion source Tb can be elemental Tb.

[0104] In the present application, the diffusion source Tb can be a Tb-M alloy, and M can be one or more of Cu, Al, Co, Ga, Zr and Ti. In this case, the mass percentage of M in the Tb-M alloy can be no more than 40%.

[0105] In the present application, the diffusion source Tb can be a hydride of Tb or a fluoride of Tb.

[0106] In the present application, the temperature for the grain boundary diffusion can be 750-950℃, for example 900℃.

[0107] In the present application, the time for the grain boundary diffusion can be 5-30h, for example 10h.

[0108] In the present application, the grain boundary diffusion can be followed by an aging treatment.

[0109] In this case, the temperature for the aging treatment can be 300-600℃, for example 500℃.

[0110] In this case, the time for the aging treatment can be 1-10h, for example 3h.

[0111] In a third aspect, the present application provides a Nd-Fe-B magnet prepared by the method as described above.

[0112] In a fourth aspect, the present application provides a use of the Nd-Fe-B magnet as described above in a magnetic steel.

[0113] Without departing from the common general knowledge in the art, the above preferred conditions can be combined in any manner to obtain various preferred embodiments of the present application.

[0114] The reagents and raw materials used in the present application are commercially available.

[0115] The positive progress effect of the present application is that:

[0116] The neodymium iron boron (NdFeB) magnet of this invention includes a transition region. By controlling the Tb and Dy contents introduced by diffusion in the transition region, the easily demagnetized region, and the non-easily demagnetized region, the interdiffusion of Tb or Dy across regions caused by the Tb concentration gradient difference in the transition region can be reduced. This reduces the gradient decrease in the performance of the boundary region and weakens the anti-demagnetization effect. While maintaining the remanence of the NdFeB magnet, the attenuation of the surface magnetism and magnetic flux of the NdFeB magnet is reduced, thus improving the anti-demagnetization capability of the NdFeB magnet. Furthermore, this invention sets the easily demagnetized region, the non-easily demagnetized region, and the transition region as an inner ellipse and an outer square, which can improve the anti-demagnetization capability of the four long sides of the NdFeB magnet. Attached Figure Description

[0117] Figure 1 This is a schematic diagram of the structure of each region of the neodymium iron boron magnet of the present invention;

[0118] Figure 2 The neodymium iron boron magnet of Example 3 Figure 1 The diagram shows the coercivity of test lines 1 to 4.

[0119] Figure 3 The neodymium iron boron magnet of Example 3 Figure 1 The diagram shows the diffusion increment of Tb for test lines 1 to 4. Detailed Implementation

[0120] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0121] Examples 1-3 and Comparative Examples 1-2

[0122] On the upper and lower surfaces of a NdFeB substrate along the Z-axis, Dy is sprayed over the entire area of ​​both surfaces, and Tb is sprayed over the outer annular region along the Z-axis. The dewaxing temperature is 200°C, and grain boundary diffusion parallel to the orientation direction is performed to obtain the NdFeB magnet. Figure 1 As shown; among them, the utilization rate of Dy or Tb in the diffusion source is 85%-95%.

[0123] The heat treatment during grain boundary diffusion is carried out at a temperature of 900℃ for 10 hours. After the heat treatment, an aging treatment is also included, which is carried out at a temperature of 500℃ for 3 hours.

[0124] The parameters of each region of the NdFeB magnets in Examples 1-3 and Comparative Examples 1-2 are listed in Tables 1-3 below. Specifically, the NdFeB magnet in Example 3... Figure 1 The changes in Tb content shown in test lines 1 to 4 are as follows: Figure 3The test line 1 is parallel to the X-axis direction and passes through the easy demagnetization region, the transition region and the non-easy demagnetization region, and overlaps with the long axis of the non-easy demagnetization region, the test line 2 is parallel to the X-axis direction and passes through the easy demagnetization region, the transition region and the non-easy demagnetization region, the test line 3 is parallel to the X-axis direction and passes through the easy demagnetization region and the transition region, and the test line 4 is parallel to the X-axis direction and passes through the easy demagnetization region. The element content of the neodymium-iron-boron base material used in Examples 1-3 and Comparative Examples 1-2 is shown in Table 4.

[0125] The thickness of the neodymium-iron-boron magnet of the neodymium-iron-boron magnet of Examples 1-3 and Comparative Examples 1-2 is 3 mm. The shell layer of the main phase grains of the easy demagnetization region and the transition region each comprises an inner shell layer and an outer shell layer, and the main phase grains of the non-easy demagnetization region only comprise an inner shell layer. The main phase and Re phase particle size and shell layer of each region of the neodymium-iron-boron of Examples 1-3 and Comparative Examples 1-2 are shown in Tables 5-6.

[0126] Table 1 Diffusion increments of Dy and Tb in each region of the neodymium-iron-boron magnet prepared in Examples 1-3 and Comparative Examples 1-2

[0127]

[0128] Table 2 Diffusion increments of Dy and Tb in the interface of the neodymium-iron-boron magnet prepared in Examples 1-3 and Comparative Examples 1-2

[0129]

[0130] Table 3 Size ratio of each region of the neodymium-iron-boron magnet prepared in Examples 1-3 and Comparative Examples 1-2

[0131]

[0132] Table 4 Mass concentration (wt%) of each element in the neodymium-iron-boron base material of Examples 1-3 and Comparative Examples 1-2

[0133]

[0134] Table 5 Main phase and Re phase particle size and shell layer of each region of the neodymium-iron-boron of Examples 1-3 and Comparative Examples 1-2

[0135]

[0136] Table 6 Main phase particle size and shell layer of each region of the neodymium-iron-boron of Examples 1-3 and Comparative Examples 1-2

[0137]

[0138] Effect example

[0139] I. Test object: neodymium-iron-boron magnet of Examples 1-3 and Comparative Examples 1-2;

[0140] II. Test method

[0141] 1. Coercivity test: The samples of Examples 1-3 and Comparative Examples 1-2 were prepared with a size of W2-3±0.1*L19±0.1*T4±0.1 mm, two pieces were stacked, and a size of W3*L19-20*T2.7 mm coil was used to test the samples in a permanent magnet precision measurement system NIM-62000 at room temperature (temperature ≤200℃).

[0142] 2. Demagnetization rate test: An electromagnetic simulation software, model Ansys Workbench, was used to input a rotating speed of 13000 rpm, and then the temperature was adjusted to the corresponding temperature working condition. The back electromotive force data of the motor and the magnetic steel cloud map changes were collected under the same time to identify whether demagnetization occurred. The calculation formula of the demagnetization rate was: demagnetization rate = (high-temperature back electromotive force - room-temperature back electromotive force) / room-temperature back electromotive force.

[0143] 3. Line scan test: The selected area of the magnet surface was microphotographed under the equipment EMMA, model JEOL 8530f, with a magnification of X3000, and the two main phases were pulled and scanned, representing the distribution of elements such as Dy / Nd.

[0144] III. Test results: listed in Tables 7-8 below:

[0145] Table 7 Coercivity and demagnetization resistance of each zone in the magnet of Examples 1-3 and Comparative Examples 1-2

[0146]

[0147] Table 8 Coercivity ratio of each zone in the magnet of Examples 1-3 and Comparative Examples 1-2

[0148] Coercivity ratio of easy demagnetization zone, transition zone and non-easy demagnetization zone Example 1 1:0.959:0.957 Example 2 1:0.930:0.909 Example 3 1:0.970:0.876 Comparative Example 1 1:0.945:0.936 Comparative Example 2 1:0.900:0.668

[0149] As shown in the above table, the demagnetization rate of the neodymium-iron-boron magnet of Examples 1-3 at 130℃ was only 2.0%-5.2%. The coercivity ratio of the transition zone to the easy demagnetization zone of the neodymium-iron-boron magnet prepared in Examples 1-3 was between (0.93-0.97): 1, and the coercivity difference between the easy demagnetization zone and the non-easy demagnetization zone was between 0.75-1.67 kOe, which had excellent demagnetization resistance. Among them, the coercivity of the neodymium-iron-boron magnet of Example 3 along the test line 1 to the test line 4 changed as shown in Figure 1 Figure 2

[0150] ​​The Tb diffusion increment of the easy demagnetization zone of Comparative Example 1 is too low, and the ratio of the Dy increment of the non-easy demagnetization zone is 3:11. The ratio of the coercivity of the easy demagnetization zone to the non-easy demagnetization zone of the Nd-Fe-B magnet of Comparative Example 1 is about 1:0.936, the difference of the coercivity of the easy demagnetization zone and the non-easy demagnetization zone is 1.5 kOe, and the anti-demagnetization ability of the Nd-Fe-B magnet prepared in Comparative Example 1 is poor, and the demagnetization rate at 130℃ is 20.2%, which is higher than that of Examples 1-3.

[0151] The Dy diffusion increment of the non-easy demagnetization zone of Comparative Example 2 is too low, and the Tb diffusion increment of the easy demagnetization zone is slightly high (1wt%). The Tb diffusion increment of the transition zone is too low, and the ratio of the Tb diffusion increment of the easy demagnetization zone is 1:5. The Dy diffusion increment of the transition zone and the non-easy demagnetization zone is ≤0.1wt%. The ratio of the coercivity of the non-easy demagnetization zone to the easy demagnetization zone of the Nd-Fe-B magnet prepared in Comparative Example 2 is 0.668:1, the difference of the coercivity of the easy demagnetization zone and the non-easy demagnetization zone is 8.7kOe, and the anti-demagnetization ability of the Nd-Fe-B magnet prepared in Comparative Example 2 is poor, and the demagnetization rate at 130℃ is as high as 19.6%, which is much higher than that of Examples 1-3, and the coercivity of the transition zone and the non-easy demagnetization zone is lower than that under the working condition, and demagnetization occurs.

[0152] The above-described examples are only better examples of the present application, and facilitate the understanding and use of the present application by those skilled in the art. Obviously, any skilled person in the art can make slight modifications or changes to the present examples without creative labor, and apply them to other examples. Therefore, the present application is not limited to the above-described examples, and any equivalent changes, simple modifications and modifications within the scope of the present application still belong to the scope of the present application.

Claims

1. A neodymium-iron-boron magnet, characterized in that A three-dimensional rectangular coordinate system is established, with an orientation direction as the Z-axis direction, and an origin of the three-dimensional rectangular coordinate system is located in the Nd-Fe-B magnet; The Nd-Fe-B magnet comprises a non-easy demagnetization area, a transition area and an easy demagnetization area; the easy demagnetization area is an annular area on the upper surface of the Nd-Fe-B magnet along the Z-axis direction, and the non-easy demagnetization area is a central area on the upper surface of the Nd-Fe-B magnet along the Z-axis direction; the transition area is an interface area between the easy demagnetization area and the non-easy demagnetization area; A content ratio of Tb in the non-easy demagnetization area, the transition area and the easy demagnetization area is (0-0.05):(0.95-1):1; A content ratio of Dy in the non-easy demagnetization area, the transition area and the easy demagnetization area is 1:1:1; A ratio of a diffusion increment of Tb in the easy demagnetization area to a diffusion increment of Tb in the non-easy demagnetization area is (1-36):1; A ratio of a diffusion increment of Tb in the easy demagnetization area to a diffusion increment of Tb in the transition area is (1-1.1):1; The diffusion increment of Tb in the easy demagnetization area is 0.1wt%-0.55wt%; The diffusion increment of Dy in the easy demagnetization area is 0.1wt%-0.55wt%; On any plane perpendicular to the orientation direction, the shape of the non-easy demagnetization area is an ellipse; The Nd-Fe-B magnet is a cuboid.

2. The neodymium-iron-boron magnet according to claim 1, characterized in that The content of heavy rare earth at each position in the easy demagnetization area is the same; And / or, the diffusion increment of heavy rare earth at the same X-Y position along the Z-axis direction in the transition area is the same; And / or, the content of Tb at any two same X-Y positions in the easy demagnetization area is the same; And / or, the content of Dy at any two positions in the easy demagnetization area, the transition area and the non-easy demagnetization area is the same; And / or, a content ratio of Tb in the transition area to the non-easy demagnetization area is 1:(0-0.1); And / or, a ratio of a diffusion increment of Tb in the easy demagnetization area to a diffusion increment of Tb in the non-easy demagnetization area is 9:1 or 36:1; And / or, a ratio of a diffusion increment of Tb in the easy demagnetization area to a diffusion increment of Tb in the transition area is 1:1, 36:34 or 55:52; And / or, the diffusion increment of Tb in the easy demagnetization area is 0.35wt%, 0.36wt%, 0.45wt% or 0.55wt%; And / or, the diffusion increment of Tb in the non-easy demagnetization area is 0-0.1wt%; And / or, the diffusion increment of Tb in the transition area is 0.1wt%-1wt%; And / or, the diffusion increment of Dy in the non-easy demagnetization area is 0.1wt%-1wt%; And / or, the diffusion increment of Dy in the transition area is 0.1wt%-1wt%; And / or, there is an interface A between the transition area and the easy demagnetization area, and the content of heavy rare earth at each position of the interface A is the same; And / or, there is an interface B between the transition area and the non-easy demagnetization area, and the content of heavy rare earth at each position of the interface B is the same; And / or, a ratio of coercivity of the easy demagnetization area to the non-easy demagnetization area is 1:(0.7-0.96). And / or, the coercivity ratio of the easy demagnetization zone and the transition zone is 1: (0.93-1); And / or, the coercivity at each position of the easy demagnetization zone is the same; And / or, the coercivity at each position of the transition zone along the Z-axis direction is the same; And / or, the remanence at each position of the easy demagnetization zone is the same; And / or, the remanence at each position of the transition zone along the Z-axis direction is the same.

3. The neodymium-iron-boron magnet according to claim 2, characterized in that The diffusion content of Tb in the transition zone along the X-axis or Y-axis direction away from the easy demagnetization zone decreases; And / or, the content ratio of Tb of the transition zone and the non-easy demagnetization zone is 1: (0-0.05); And / or, the diffusion increment of Tb of the non-easy demagnetization zone is 0-0.05wt%; And / or, the diffusion increment of Tb of the transition zone is 0.34wt%, 0.45wt% or 0.52wt%; And / or, the diffusion increment of Dy of the non-easy demagnetization zone is 0.4wt%-0.7wt%; And / or, the diffusion increment of Dy of the transition zone is 0.55wt%; And / or, the diffusion increment of Tb of the interface A is 0.3wt%-0.7wt%; And / or, the diffusion increment ratio of Tb of the interface A and the easy demagnetization zone is (0.95-1): 1; And / or, the diffusion increment of Dy of the interface A is 0.4wt%-0.7wt%; And / or, the diffusion increment of Tb of the interface B is 0.3wt%-0.7wt%, And / or, the diffusion increment ratio of Tb of the interface B and the non-easy demagnetization zone is (6-60): 1, And / or, the diffusion increment of Dy of the interface B is 0.4wt%-0.7wt%; And / or, the coercivity ratio of the easy demagnetization zone and the non-easy demagnetization zone is 1: 0.876, 1: 0.909 or 1:0.957; And / or, the coercivity ratio of the easy demagnetization zone and the transition zone is 1: 0.930, 1: 0.959 or 1: 0.970; And / or, the coercivity in the transition zone along the X-axis or Y-axis direction away from the easy demagnetization zone direction decreases; And / or, the remanence in the transition zone along the X-axis or Y-axis direction away from the easy demagnetization zone direction decreases.

4. The neodymium-iron-boron magnet according to claim 3, characterized in that The diffusion increment of Dy of the non-easy demagnetization zone is 0.55wt%; And / or, the diffusion increment of Tb of the non-easy demagnetization zone is 0, 0.01wt% or 0.05wt%; And / or, the diffusion increment of Tb of the interface A is 0.36wt%, 0.45wt% or 0.55wt%; And / or, the diffusion increment of Dy of the interface A is 0.55wt%; And / or, the diffusion increment of Tb of the interface B is 0.34wt%, 0.43wt% or 0.52wt%; And / or, the diffusion increment ratio of Tb of the interface B and the non-easy demagnetization zone is 43: 5, 34: 1 or 52: 1; And / or, the diffusion increment of Dy of the interface B is 0.55wt%.

5. The neodymium-iron-boron magnet according to claim 1, characterized in that The neodymium-iron-boron magnet is represented by the formula R1-R2-T-B-M, wherein R1 is one or more of Pr, Nd, Ce, Er, Tm, Y, Lu, Gd and Ho; R2 is Dy and / or Tb; T is one or more of Fe, Zn, Si, V, Cr, Mn, Ni, Ge, Nb, Mo, Pd, Ag, Cd, Sb, Hf, Ta, W, O, C, N, S, F and P; and M is one or more of Cu, Al, Co, Ga, Zr and Ti; and / or the microstructure of the neodymium-iron-boron magnet comprises Re2Fe 14 B main phase grains and Re-rich phase grain boundaries; the Re2Fe 14 B main phase grains comprise a core layer and a shell layer; the Re is one or more of Nd, Dy, and Tb.

6. The neodymium-iron-boron magnet according to claim 5, characterized in that The M element is all from the neodymium-iron-boron base material; And / or, the M element contains a diffusion-introduced M element.

7. The neodymium-iron-boron magnet according to claim 6, characterized in that The diffusion-introduced M element accounts for 0-0.4% of the mass percentage of the neodymium-iron-boron magnet.

8. The neodymium-iron-boron magnet according to claim 5, characterized in that Re2Fe of the easy demagnetization zone 14 The difference of the particle size of the B main phase crystal grains is not more than 8 μm. and / or, the transition zone has a Re2Fe 14 The difference in the particle size of the B main phase grains is not more than 8 μm. and / or the Re2Fe14C phase in the surface layer of the easy demagnetization region, the transition region, and the non-easy demagnetization region 14 The particle size of the B main phase grains is equal. and / or, Re2Fe 14 The particle size of the B main phase grains is equal. and / or, in the easy demagnetization zone, the transition zone and the non-easy demagnetization zone, the surface layer has a Re2Fe 14 The particle size of the B main phase crystal grains is 1-1.5 times the particle size of the central main phase crystal grains. and / or, the Re2Fe of the easy demagnetization zone, the transition zone and the non-easy demagnetization zone are the same X-Y plane 14 The size ratio of the B main phase crystal grains is 1:1:

1. and / or the Re2Fe 14 The particle size of the B main phase crystal grains is 1-12 μm. And / or, the thickness of the Re-rich phase grain boundary of the easy demagnetization region is equal; And / or, the thickness of the Re-rich phase grain boundary of the transition region is equal; And / or, the thickness of the Re-rich phase grain boundary of the easy demagnetization region is 0.4-1 μm; And / or, the thickness of the Re-rich phase grain boundary of the transition region is 0.4-1 μm; And / or, the thickness of the Re-rich phase grain boundary of the non-easy demagnetization region is 0.2-0.5 μm.

9. The neodymium-iron-boron magnet according to claim 8, characterized in that The thickness of the Re-rich phase grain boundary of the easy demagnetization region is 0.5 μm or 0.55 μm; And / or, the thickness of the Re-rich phase grain boundary of the transition region is 0.5 μm or 0.52 μm; And / or, the thickness of the Re-rich phase grain boundary of the non-easy demagnetization region is 0.20 μm, 0.23 μm or 0.25 μm.

10. The neodymium-iron-boron magnet according to claim 5, characterized in that The shell layer of the demagnetization easy zone is (Nd, Dy, Tb)2Fe 14 B hard magnetic layer; and / or the shell layer of the non-coercive region is (Nd, Dy)2Fe 14 B hard magnetic layer; And / or, the core layer and the shell layer in the easy demagnetization region, the transition region and the non-easy demagnetization region each independently satisfy the following conditions: the R1 content in the core layer is not less than the R1 content in the shell layer; and the R2 content in the core layer is less than the R2 content in the shell layer; And / or, the R2 is Tb, and the content of R2 in the easy demagnetization region, the transition region and the non-easy demagnetization region satisfies the following condition: easy demagnetization region ≥ transition region > non-easy demagnetization region; And / or, the R2 is Dy, and the content of R2 in the easy demagnetization region, the transition region and the non-easy demagnetization region satisfies the following condition: non-easy demagnetization region = transition region = easy demagnetization region; And / or, the thickness of the shell layer of the easy demagnetization region is equal; And / or, the thickness of the shell layer of the transition region is equal; And / or, the thickness of the shell layer of the easy demagnetization region is 2-3 μm; And / or, the thickness of the shell layer of the main phase grain of the transition region is 2-2.5 μm; And / or, the thickness of the shell layer of the main phase grain of the non-easy demagnetization region is 0.5-2 μm; And / or, the thickness ratio of the shell layer and the Re-rich phase grain boundary of the easy demagnetization region is (2-3):(0.4-1); And / or, the thickness ratio of the shell layer and the Re-rich phase grain boundary of the transition region is (2-2.5):(0.4-1); And / or, the thickness ratio of the shell layer and the Re-rich phase grain boundary of the main phase grain of the non-easy demagnetization region is (0.5-2):(0.2-0.5).

11. The neodymium-iron-boron magnet according to claim 10, characterized in that The thickness of the shell layer of the easy demagnetization region is 2 μm, 2.1 μm or 2.5 μm; And / or, the thickness of the shell layer of the main phase grains of the transition zone is 2 μm or 2.38 μm; And / or, the thickness of the shell layer of the main phase grains of the non-remanence zone is 0.95 μm, 1.0 μm or 1.1 μm; And / or, the thickness ratio of the shell layer of the easy remanence zone and the Re-rich phase grain boundary is 4:1, 2.1:0.5 or 2.5:0.55; And / or, the thickness ratio of the shell layer of the transition zone and the Re-rich phase grain boundary is 4:1 or 2.38:0.52; And / or, the thickness ratio of the shell layer of the main phase grains of the non-remanence zone and the Re-rich phase grain boundary is 1.1:0.25, 1.0:0.23 or 0.95:0.

20. The origin is located at the center of the upper surface of the cuboid; the X axis of the three-dimensional rectangular coordinate system is parallel to one side of the upper surface; the length-width ratio of the neodymium-iron-boron magnet is (2-5):1; 12. The neodymium-iron-boron magnet according to claim 1, characterized in that And / or, the width of the easy remanence zone is equal; And / or, the length-width ratio of the non-remanence zone is (2-15):1; And / or, the width of the transition zone is equal; And / or, the volume percentage of the easy remanence zone in the volume of the neodymium-iron-boron magnet is 50%-90%; And / or, the volume percentage of the transition zone in the volume of the neodymium-iron-boron magnet is 0-28.4%; And / or, the volume percentage of the non-remanence zone in the volume of the neodymium-iron-boron magnet is 15.7%-44.11%; And / or, the thickness of the neodymium-iron-boron magnet is not more than 5 mm. The length-width ratio of the neodymium-iron-boron magnet is (2.42-3.7):1; 13. The neodymium-iron-boron magnet according to claim 12, characterized in that And / or, the width of the easy remanence zone is not more than 5 mm; And / or, the length-width ratio of the non-remanence zone is 17.5:3.35; And / or, the width of the transition zone is 0-2 mm, not 0; And / or, the volume percentage of the easy remanence zone in the volume of the neodymium-iron-boron magnet is 47.85%; And / or, the volume percentage of the transition zone in the volume of the neodymium-iron-boron magnet is 8.04%; And / or, the thickness of the neodymium-iron-boron magnet is 3 mm. The length-width ratio of the neodymium-iron-boron magnet is 3:1, 3.65:1 or 39:10.7; 14. The neodymium-iron-boron magnet according to claim 13, characterized in that And / or, the width of the easy remanence zone is 2-4 mm; And / or, the width of the transition zone is 0.5 mm. It comprises the following steps: on the neodymium-iron-boron substrate, respectively on the upper surface and / or the lower surface perpendicular to the Z axis direction, a diffusion source is applied, and grain boundary diffusion parallel to the orientation direction is carried out; wherein, the diffusion source Dy is applied on the entire area of the upper surface and the lower surface, and the diffusion source Tb is applied on the annular area along the outer edge of the Z axis direction, forming the easy remanence zone, the transition zone and the non-remanence zone.

15. A method of producing a neodymium-iron-boron magnet, characterized by, The diffusion source is applied by coating; 16. The method of producing a neodymium-iron-boron magnet according to claim 15, characterized by, And / or, the diffusion source Dy satisfies any one of the following conditions ①-③: ①The diffusion source Dy is Dy element; ②The diffusion source Dy is Dy-M alloy; ③The diffusion source Dy is hydride of Dy or fluoride of Dy; ​ And / or, the diffusion source Tb satisfies any one of conditions ①-③: ① The diffusion source Tb is Tb single element; ② The diffusion source Tb is Tb-M alloy; ③ The diffusion source Tb is hydride of Tb or fluoride of Tb; And / or, the temperature of the grain boundary diffusion is 750-950℃; And / or, the time of the grain boundary diffusion is 5-30 h; And / or, the grain boundary diffusion is followed by aging treatment.

17. The method of producing a neodymium-iron-boron magnet according to claim 16, characterized by, The coating method is spraying or printing; And / or, when the diffusion source is applied by coating method, the diffusion source is mixed with solvent and binder to form slurry; And / or, the temperature of the grain boundary diffusion is 900℃; And / or, the time of the grain boundary diffusion is 10 h; And / or, the temperature of the aging treatment is 300-600℃; And / or, the time of the aging treatment is 1-10 h.

18. The method of producing a neodymium-iron-boron magnet according to claim 17, characterized by, The dewaxing temperature of the spraying is 200-400℃; or the dewaxing temperature of the printing is 100-500℃; And / or, the solvent is water, alcohol, ketone or ester; And / or, the mass percentage of Dy or Tb in the diffusion source in the slurry is 0.3%-1%; And / or, the temperature of the aging treatment is 500℃; And / or, the time of the aging treatment is 3 h.

19. The method of making a neodymium-iron-boron magnet according to claim 16, wherein, When the diffusion source Dy satisfies condition ②, the M is one or more of Cu, Al, Co, Ga, Zr and Ti; And / or, when the diffusion source Dy satisfies condition ②, the mass percentage of M in the Dy-M alloy is not more than 40%.

20. The method of making a neodymium-iron-boron magnet of claim 16, wherein, When the diffusion source Tb satisfies condition ②, the M is one or more of Cu, Al, Co, Ga, Zr and Ti; And / or, when the diffusion source Tb satisfies condition ②, the mass percentage of M in the Tb-M alloy is not more than 40%.

21. A neodymium-iron-boron magnet prepared by the method of any one of claims 15-20.

22. Use of the neodymium-iron-boron magnet of any one of claims 1-14 and 21 in a magnetic steel.

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