High-flux district dispersing agent and application thereof

Abstract

The invention relates to a high-flux selective diffusion agent and application thereof. The high-flux selective diffusion agent is obtained by mixing heavy rare earth-containing spherical powder and a solid organic binder and then melting and processing; the particle size of the heavy rare earth-containing spherical powder is 10-60 [mu] m, and the sphericity is greater than 85%. According to the method, the heavy rare earth-containing spherical powder with high sphericity degree and good fluidity and the raw material suitable for additive manufacturing are adopted, and the comprehensive magnetic performance of the subsequently prepared magnet can be remarkably improved by strictly controlling the morphology of the heavy rare earth-containing spherical powder. According to the method, the high-flux selected area dispersion technology is combined with the additive manufacturing means, selected area diffusion is conducted on the surface of the neodymium-iron-boron magnet, and the coercive force and high-temperature stability of the neodymium-iron-boron magnet can be greatly improved under the condition that the use amount of heavy rare earth is small. The method is suitable for multi-batch and small-batch production exploration and has the advantages of being high in technological process automation process and short in research and development period.

Description

Technical Field

[0001] The present invention relates to the technical field of neodymium-iron-boron permanent magnet preparation, and particularly relates to a high-throughput selective area diffusing agent and its application. Background Art

[0002] The grain boundary diffusion technology of neodymium-iron-boron magnets is to coat the surface of neodymium-iron-boron magnets with inorganic compounds or alloy materials of heavy rare earths. Through subsequent heat treatment, heavy rare earth elements diffuse into the magnets along the molten grain boundary phase, which can greatly improve the coercivity and high-temperature stability of the magnets. However, it is difficult to process neodymium-iron-boron magnets with a large thickness by this method, and the usage amount of heavy rare earths still needs to be further reduced.

[0003] The selective area diffusion technology has been proven to be a grain boundary diffusion technology that can achieve diffusion of thick magnets and can greatly reduce the usage amount of heavy rare earths. Selective area diffusion is to coat the diffusing agent on the weak areas of the magnet, such as the vertices and edges of a cuboid magnet. By means of focused strengthening, thick magnets can be processed and the usage amount of heavy rare earths can be further reduced. For example, CN117497276A discloses an R-T-Ga-B rare earth permanent magnet based on optional area grain boundary diffusion and its preparation method. A diffusion source is selectively coated on the diffusion surface of the neodymium-iron-boron magnet substrate, and in the corner area of the diffusion surface, the diffusion source is coated. The diffusion source is a mixed dry powder of heavy rare earth and metal Ga. Then, diffusion treatment is carried out to obtain an R-T-Ga-B rare earth permanent magnet based on optional area grain boundary diffusion. In this invention, the Ga content is increased by diffusion in the corner area to ensure the coercivity, while the core part ensures relatively low Ga to ensure high remanence and improve the comprehensive performance of the magnet.

[0004] In addition, the current diffusing agents used in selective area diffusion are mainly prepared by mixing inorganic compounds or alloy powders of heavy rare earths with colloids into slurries, and then through screen printing, a diffusing agent slurry with a specific pattern is printed on the surface of the magnet. After the slurry is solidified and formed, heat treatment is carried out to diffuse the diffusing agent into the magnet interior. For example, CN110890210A discloses a method for improving the coercivity of arc-shaped neodymium-iron-boron magnets. Heavy rare earth powder is mixed and stirred with an organic binder and an organic solvent to form a heavy rare earth slurry. A layer of heavy rare earth slurry is coated on a flexible film by screen printing and solidified to form a heavy rare earth coating. Then, the heavy rare earth coating is transferred to the surface to be diffused of the arc-shaped magnet and pressurized. Then, the arc-shaped neodymium-iron-boron magnet with the heavy rare earth coating attached is subjected to high-temperature diffusion aging treatment. However, screen printing requires a bottom plate with a fixed pattern, which consumes a lot during the exploration process, has low production efficiency, is not suitable for multi-batch and small-batch production, and the traditional inorganic compounds or alloy powders of heavy rare earths are generally made by chemical synthesis or alloy crushing methods, with irregular morphologies and poor fluidity, which have certain limitations in the application of diffusing agents.

[0005] In summary, there is an urgent need to provide a diffusing agent powder raw material with high sphericity and good fluidity, and a selective area diffusion method suitable for multi-batch and small-batch production. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a high-throughput selective area diffusing agent and its application, which can greatly improve the coercivity of Nd-Fe-B magnets with less heavy rare earth consumption.

[0007] To achieve the purpose of this invention, the following technical solutions are adopted:

[0008] In the first aspect, the present invention provides a high-throughput selective area diffusing agent, which is obtained by melt-processing a mixture of heavy rare earth-containing spherical powder and a solid organic binder;

[0009] The particle size of the heavy rare earth-containing spherical powder is 10-60 μm, and the sphericity > 85%.

[0010] The high-throughput selective area diffusing agent provided by the present invention uses heavy rare earth-containing spherical powder with high sphericity and good fluidity, which is suitable as a raw material for additive manufacturing. By strictly controlling the morphology of the heavy rare earth-containing spherical powder, the comprehensive magnetic properties of the subsequently prepared Nd-Fe-B magnets can be significantly improved.

[0011] The particle size of the heavy rare earth-containing spherical powder is 10-60 μm, for example, it can be 10 μm, 12 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 48 μm, 50 μm, 55 μm or 60 μm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0012] The sphericity of the heavy rare earth-containing spherical powder > 85%, for example, it can be 86%, 88%, 90%, 92% or 95%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0013] Preferably, the heavy rare earth-containing spherical powder includes at least one of heavy rare earth metal simple substances, heavy rare earth alloys or heavy rare earth compounds.

[0014] Preferably, the heavy rare earth metal simple substances include Tb and Dy.

[0015] Preferably, the heavy rare earth alloy is alloy HRE-M, where HRE includes Tb and Dy, and M includes at least one of Nd, Pr, Ce, La, Al, Cu, Zn, Mg or Ni.

[0016] Preferably, based on the total mass percentage content of 100 wt%, in the alloy HRE-M, the mass percentage content of HRE is 15-90 wt%, and the balance is M.

[0017] The mass percentage content of HRE in the alloy HRE-M is 15-90 wt%, for example, it can be 15 wt%, 30 wt%, 50 wt%, 70 wt% or 90 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0018] Preferably, the heavy rare earth compound is HRE-X, where HRE includes Tb and Dy, and X includes F and / or H.

[0019] Preferably, the spherical heavy rare earth-containing powder is prepared by the aerosol method.

[0020] The spherical heavy rare earth-containing powder is prepared by the aerosol method, with a relatively regular morphology and good fluidity, and is suitable as a raw material for additive manufacturing.

[0021] Preferably, the solid organic binder includes any one or a combination of at least two of PVB particles, PVA particles or acrylic resin particles. Typical but non-limiting combinations include the combination of PVB particles and PVA particles, the combination of PVA particles and acrylic resin particles, or the combination of PVB particles, PVA particles and acrylic resin particles.

[0022] Preferably, the mass of the solid organic binder is 2-4 wt% of the mass of the spherical heavy rare earth-containing powder. For example, it can be 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt% or 4 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0023] Preferably, the melt processing includes extrusion or injection molding.

[0024] Preferably, based on the total mass percentage of 100 wt%, in the high-throughput selective area diffusing agent, the mass percentage content of HRE is 15-95 wt%, the total mass percentage content of C and O is 4.8-20 wt%, and the balance is the doping component.

[0025] The mass percentage content of HRE in the high-throughput selective area diffusing agent is 15-95 wt%, for example, it can be 15 wt%, 30 wt%, 50 wt%, 70 wt% or 95 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0026] The total mass percentage content of C and O in the high-throughput selective area diffusing agent is 4.8-20 wt%, for example, it can be 4.8 wt%, 7 wt%, 10 wt%, 15 wt% or 20 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0027] Preferably, the HRE includes Tb and Dy with a mass ratio of (0.3-1.7):1. For example, it can be 0.3:1, 0.5:1, 0.8:1, 1:1, 1.2:1, 1.5:1 or 1.7:1, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0028] Preferably, the doping component includes at least one of H, F, Nd, Pr, Ce, La, Al, Cu, Zn, Mg or Ni.

[0029] Preferably, when the doping component contains H, the mass percentage content of H is 0.2-1 wt%. For example, it can be 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt% or 1 wt%, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0030] Preferably, when the doping component contains F, the mass percentage content of F is 10-30 wt%. For example, it can be 10 wt%, 15 wt%, 20 wt%, 25 wt% or 30 wt%, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0031] Preferably, when the doping component contains Nd, the mass percentage content of Nd is 8-60 wt%. For example, it can be 8 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt% or 60 wt%, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0032] Preferably, when the doping component contains Pr, the mass percentage content of Pr is 8-60 wt%. For example, it can be 8 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt% or 60 wt%, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0033] Preferably, when the doping component contains Ce, the mass percentage content of Ce is 5-20 wt%. For example, it can be 5 wt%, 8 wt%, 10 wt%, 15 wt% or 20 wt%, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0034] Preferably, when the doping component contains La, the mass percentage content of La is 5-20 wt%. For example, it can be 5 wt%, 8 wt%, 10 wt%, 15 wt% or 20 wt%, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0035] Preferably, when the doping component contains Al, the mass percentage of Al is 1-12 wt%, for example, it can be 1 wt%, 3 wt%, 5 wt%, 8.2 wt% or 12 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0036] Preferably, when the doping component contains Cu, the mass percentage of Cu is 4-25 wt%, for example, it can be 4 wt%, 6 wt%, 10 wt%, 15 wt%, 20 wt% or 25 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0037] Preferably, when the doping component contains Zn, the mass percentage of Zn is 4-25 wt%, for example, it can be 4 wt%, 6 wt%, 10 wt%, 15 wt%, 20 wt% or 25 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0038] Preferably, when the doping component contains Mg, the mass percentage of Mg is 1-10 wt%, for example, it can be 1 wt%, 3 wt%, 5 wt%, 8 wt% or 10 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0039] Preferably, when the doping component contains Ni, the mass percentage of Ni is 2-20 wt%, for example, it can be 2 wt%, 5 wt%, 10 wt%, 15 wt% or 20 wt%, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0040] In a second aspect, the present invention provides an application of the high-throughput selective area diffusing agent as described in the first aspect. The high-throughput selective area diffusing agent is used in the high-throughput selective area diffusion of neodymium-iron-boron magnets. The method of the high-throughput selective area diffusion includes the following steps:

[0041] (1) Process the neodymium-iron-boron magnet to obtain a magnet to be diffused;

[0042] (2) Design different patterns with a gradient distribution in size, and then print the high-throughput selective area diffusing agent on the edge area of the magnetic pole surface of the magnet to be diffused obtained in step (1) by additive manufacturing to obtain a printed magnet;

[0043] (3) The printed magnet obtained in step (2) is subjected to diffusion heat treatment to obtain a diffused magnet; the magnetic properties of the obtained diffused magnet are detected to obtain the diffused magnet with the optimal printed pattern.

[0044] The high-throughput selective area diffusing agent provided by the present invention is used for high-throughput selective area diffusion of NdFeB magnets. By adopting the high-throughput selective area dispersion technology combined with additive manufacturing means, selective area diffusion is carried out on the surface of the NdFeB magnet. Through subsequent diffusion heat treatment, heavy rare earth elements diffuse into the NdFeB magnet along the molten grain boundary phase, and the coercivity and high-temperature stability of the NdFeB magnet can be greatly improved with less heavy rare earth usage. The high-throughput selective area diffusion method described in the present invention is applicable to production exploration in multiple batches and small batches, and has the characteristics of high automation in the process flow and fast R & D cycle.

[0045] Preferably, the processing in step (1) includes cutting and grinding and polishing.

[0046] Preferably, the shape of the magnet to be diffused in step (1) includes any one of prismatic, cylindrical or tile-shaped.

[0047] Preferably, the shape of the unprinted area on the pole surface of the magnet to be diffused in step (2) includes a circle or a square.

[0048] Preferably, the interval of the gradient distribution of the diameter of the circle or the side length of the square is controlled to be 0.1-0.3 mm to obtain different patterns with gradient distribution of the sizes.

[0049] The interval of the gradient distribution is 0.1-0.3 mm, for example, it can be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm or 0.3 mm, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0050] Preferably, the additive manufacturing method in step (2) includes any one of electron beam melting, powder bed fusion, material extrusion or material jetting.

[0051] Preferably, after printing in step (2), there is also a step of drying at 110-130 °C, for example, it can be 110 °C, 115 °C, 120 °C, 125 °C or 130 °C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0052] Preferably, before the diffusion heat treatment in step (3), vacuum pumping and nitrogen purging are repeated.

[0053] Preferably, the vacuum degree of the diffusion heat treatment in step (3) < 5×10 -3 Pa, for example, it can be 4×10 -3 Pa, 3×10 -3 Pa, 2×10 -3 Pa, 1×10 -3 Pa or 5×10 -4Pa, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0054] The diffusion heat treatment is carried out in a vacuum atmosphere furnace. After the furnace chamber is washed with nitrogen 3 times by a mechanical pump, it is pumped to a vacuum degree < 5×10 -3 Pa again by a molecular pump.

[0055] Preferably, the diffusion heat treatment in step (3) includes a first heat treatment and a second heat treatment carried out in sequence.

[0056] Preferably, the temperature of the first heat treatment is 850 - 950 °C and the time is 3 - 5 h.

[0057] The temperature of the first heat treatment is 850 - 950 °C. For example, it can be 850 °C, 880 °C, 900 °C, 920 °C or 950 °C, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0058] The time of the first heat treatment is 3 - 5 h. For example, it can be 3 h, 3.5 h, 4 h, 4.5 h or 5 h, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0059] Preferably, the temperature of the second heat treatment is 450 - 550 °C and the time is 2 - 4 h.

[0060] The temperature of the second heat treatment is 450 - 550 °C. For example, it can be 450 °C, 480 °C, 500 °C, 520 °C or 550 °C, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0061] The time of the second heat treatment is 2 - 4 h. For example, it can be 2 h, 2.5 h, 3 h, 3.5 h or 4 h, but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0062] Preferably, cooling is carried out after the diffusion heat treatment in step (3).

[0063] Preferably, the magnetic property detection in step (3) is carried out using a permanent magnet measuring instrument.

[0064] The magnetic properties include at least one of the maximum magnetic energy product, remanence, coercivity or squareness.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] (1) The high-throughput selective area diffusing agent provided by the present invention uses heavy rare earth-containing spherical powders with high sphericity and good fluidity, which are suitable as raw materials for additive manufacturing. By strictly controlling the morphology of the heavy rare earth-containing spherical powders, the comprehensive magnetic properties of the subsequently prepared NdFeB magnets can be significantly improved.

[0067] (2) The high-throughput selective area diffusing agent provided by the present invention is used in the high-throughput selective area diffusion of NdFeB magnets. By using the high-throughput selective area dispersion technology combined with the means of additive manufacturing, selective area diffusion is carried out on the surface of the NdFeB magnet. Through subsequent diffusion heat treatment, heavy rare earth elements diffuse into the NdFeB magnet along the molten grain boundary phase, and the coercivity and high-temperature stability of the NdFeB magnet can be greatly improved with less heavy rare earth usage. The high-throughput selective area diffusion method described in the present invention is applicable to the production exploration of multiple batches and small batches, and has the characteristics of high automation in the process flow and fast R & D cycle. Description of the Drawings

[0068] Figure 1 is the printing schematic diagram provided in Embodiment 1 of the present invention;

[0069] Figure 2 is the printing schematic diagram provided in Embodiment 6 of the present invention. Detailed Embodiments

[0070] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0071] Embodiment 1

[0072] This embodiment provides a high-throughput selective area diffusing agent, which is obtained by mixing heavy rare earth-containing spherical powders prepared by the aerosol method with PVB particles and then extruding; the particle size of the heavy rare earth-containing spherical powders is 12 - 48 μm, and the sphericity is 92%; the heavy rare earth-containing spherical powders are Tb 42 Dy 43 Cu 15 (wt%); the mass of the PVB particles is 3 wt% of the mass of the heavy rare earth-containing spherical powders.

[0073] Calculated based on the total mass percentage of 100 wt%, in the high-throughput selective area diffusing agent, the total mass percentage of Tb and Dy is 75 wt%, the mass ratio of Tb to Dy is 1:1, the mass percentage of C is 5 wt%, the mass percentage of O is 10 wt%, and the balance is Cu.

[0074] The high-throughput selective area diffusing agent is used in the high-throughput selective area diffusion of NdFeB magnets. The high-throughput selective area diffusion method includes the following steps:

[0075] (1) Cut and grind the neodymium iron boron magnet to obtain a prismatic magnet to be diffused with dimensions of 10×10×4 mm, where the 4-mm thickness direction is the same as the orientation direction of the magnet to be diffused;

[0076] (2) Print the high-throughput selective area diffusing agent on the edge area of the pole surface of the magnet to be diffused obtained in step (1) by electron beam melting. The printing schematic diagram is as Figure 1 shown. The shape of the unprinted area on the pole surface is a square. Control the side length change range of the square ≤ 9.8 mm, and the interval of the gradient distribution is 0.2 mm to obtain 50 printed magnets with gradient-distributed pattern sizes, and dry them at 120 °C;

[0077] (3) After the furnace cavity of the vacuum atmosphere furnace is washed three times with a mechanical pump and nitrogen, it is pumped to a vacuum degree of 4×10 -3 Pa again by a molecular pump, and then perform the first heat treatment and the second heat treatment on the printed magnet obtained in step (2). The temperature of the first heat treatment is 900 °C and the time is 4 h. The temperature of the second heat treatment is 500 °C and the time is 3 h, and cool to obtain a diffused magnet; perform magnetic property detection on the obtained diffused magnet to obtain the diffused magnet with the optimal printed pattern.

[0078] Example 2

[0079] This example provides a high-throughput selective area diffusing agent, which is obtained by mixing spherical powders containing heavy rare earths prepared by the aerosol method and PVA particles and then extruding; the particle size of the spherical powders containing heavy rare earths is 10-45 μm, and the sphericity is 90%; the spherical powders containing heavy rare earths are Tb 45 Dy 45 Al 10 (wt%); the mass of the PVA particles is 2 wt% of the mass of the spherical powders containing heavy rare earths.

[0080] Based on the total mass percentage content of 100 wt%, in the high-throughput selective area diffusing agent, the total mass percentage content of Tb and Dy is 87 wt%, the mass ratio of Tb and Dy is 0.3:1, the mass percentage content of C is 2 wt%, the mass percentage content of O is 2.8 wt%, and the balance is Al.

[0081] The high-throughput selective area diffusing agent is used in the high-throughput selective area diffusion of neodymium iron boron magnets. The method of the high-throughput selective area diffusion includes the following steps:

[0082] (1) Cut and grind the neodymium iron boron magnet to obtain a prismatic magnet to be diffused with dimensions of 9×9×3 mm, where the 3-mm thickness direction is the same as the orientation direction of the magnet to be diffused;

[0083] (2) The high-throughput selective-area diffusing agent is printed on the edge area of the pole surface of the magnet to be diffused obtained in step (1) by powder bed melting. The shape of the unprinted area on the pole surface is square, the side length change range of the square is controlled to be ≤ 8.7 mm, and the interval of the gradient distribution is 0.3 mm, obtaining 30 printed magnets with gradient-distributed pattern sizes, and drying at 110 °C;

[0084] (3) After the furnace cavity of the vacuum atmosphere furnace is washed with nitrogen three times by a mechanical pump, it is pumped to a vacuum degree of 3×10 -3 Pa again by a molecular pump, and then the printed magnet obtained in step (2) is subjected to the first heat treatment and the second heat treatment. The temperature of the first heat treatment is 850 °C and the time is 5 h, the temperature of the second heat treatment is 450 °C and the time is 4 h, and the diffused magnet is obtained after cooling; the magnetic properties of the obtained diffused magnet are detected to obtain the diffused magnet with the optimal printed pattern.

[0085] Example 3

[0086] This example provides a high-throughput selective-area diffusing agent, which is obtained by injection molding after mixing spherical heavy rare earth-containing powder prepared by the aerosol method and acrylic resin particles; the particle size of the spherical heavy rare earth-containing powder is 20-60 μm, and the sphericity is 88%; the spherical heavy rare earth-containing powder is Tb 10 Dy 10 Nd 80 (wt%); the mass of the acrylic resin particles is 4 wt% of the mass of the spherical heavy rare earth-containing powder.

[0087] Based on the total mass percentage of 100 wt%, in the high-throughput selective-area diffusing agent, the total mass percentage of Tb and Dy is 20 wt%, the mass ratio of Tb and Dy is 1.7:1, the mass percentage of C is 10 wt%, the mass percentage of O is 10 wt%, and the balance is Nd.

[0088] The high-throughput selective-area diffusing agent is used in the high-throughput selective-area diffusion of neodymium iron boron magnets, and the method of the high-throughput selective-area diffusion includes the following steps:

[0089] (1) The neodymium iron boron magnet is cut and polished to obtain a prismatic magnet to be diffused with dimensions of 5×5×2 mm, where the 2-mm thickness direction is the same as the orientation direction of the magnet to be diffused;

[0090] (2) The high-throughput selective-area diffusing agent is printed on the edge area of the pole surface of the magnet to be diffused obtained in step (1) by material extrusion. The shape of the unprinted area on the pole surface is square, the side length change range of the square is controlled to be ≤ 4.9 mm, and the interval of the gradient distribution is 0.1 mm, obtaining 50 printed magnets with gradient-distributed pattern sizes, and drying at 130 °C;

[0091] (3) After the furnace cavity of the vacuum atmosphere furnace is washed with nitrogen 3 times by a mechanical pump, it is pumped to a vacuum degree of 2×10 -3 Pa again by a molecular pump. Then, the printed magnet obtained in step (2) is subjected to the first heat treatment and the second heat treatment. The temperature of the first heat treatment is 950°C and the time is 3 h. The temperature of the second heat treatment is 550°C and the time is 2 h. After cooling, a diffusion magnet is obtained. The magnetic properties of the obtained diffusion magnet are detected to obtain the diffusion magnet with the optimal printed pattern.

[0092] Example 4

[0093] This example provides a high-throughput selective area diffusing agent. The difference from Example 1 is that the heavy rare earth spherical powder is adjusted to Tb 50 Dy 50 (wt%). In the obtained high-throughput selective area diffusing agent, the total mass percentage content of Tb and Dy is 85 wt%, the mass ratio of Tb and Dy is 1:1, the mass percentage content of C is 4.5 wt%, the mass percentage content of O is 10 wt%, the balance is H, and the rest are the same as in Example 1.

[0094] Example 5

[0095] This example provides a high-throughput selective area diffusing agent. The difference from Example 1 is that the heavy rare earth spherical powder is adjusted to Tb 40 Dy 40 F 20 (wt%). In the obtained high-throughput selective area diffusing agent, the total mass percentage content of Tb and Dy is 70 wt%, the mass ratio of Tb and Dy is 1:1, the mass percentage content of C is 5 wt%, the mass percentage content of O is 10 wt%, the balance is F, and the rest are the same as in Example 1.

[0096] Example 6

[0097] This example provides a high-throughput selective area diffusing agent. The difference in the method of high-throughput selective area diffusion from Example 1 is that the shape of the unprinted area on the magnetic pole surface in step (2) is adjusted to a circle. The printing schematic diagram is as Figure 2 shown. The diameter change range of the circle is controlled to be ≤9.8 mm, and the interval of the gradient distribution is 0.2 mm to obtain 50 printed magnets with pattern sizes distributed in a gradient, and the rest are the same as in Example 1.

[0098] Example 7

[0099] This example provides a high-throughput selective area diffusing agent. The difference from Example 1 is that the first heat treatment and the second heat treatment in step (3) are adjusted to one-step heat treatment, the temperature is 900°C, and the time is 7 h, and the rest are the same as in Example 1.

[0100] Example 8

[0101] This example provides a high-throughput selective-area diffusing agent. The difference from Example 1 is that the first heat treatment and the second heat treatment described in step (3) are adjusted to be one-step heat treatment, with a temperature of 500 °C and a time of 7 h, and the rest are the same as in Example 1.

[0102] Comparative Example 1

[0103] This comparative example provides a high-throughput selective-area diffusing agent. The difference from Example 1 is that the particle size of the heavy rare earth-containing spherical powder is adjusted to 5 - 35 μm, and the rest are the same as in Example 1.

[0104] Comparative Example 2

[0105] This comparative example provides a high-throughput selective-area diffusing agent. The difference from Example 1 is that the particle size of the heavy rare earth-containing spherical powder is adjusted to 40 - 70 μm, and the rest are the same as in Example 1.

[0106] Comparative Example 3

[0107] This comparative example provides a high-throughput selective-area diffusing agent. The difference from Example 1 is that the sphericity of the heavy rare earth-containing spherical powder is adjusted to 80%, and the rest are the same as in Example 1.

[0108] The high-throughput selective-area diffusing agents provided in Examples 1 - 8 and Comparative Examples 1 - 3 are used for high-throughput selective-area diffusion of NdFeB magnets. The diffusion magnets with a gradient distribution of pattern sizes obtained are subjected to coercivity detection using a permanent magnet measuring instrument, the optimal effect of improving coercivity per unit weight of heavy rare earth is calculated, and the optimal printing pattern of the diffusion magnet is obtained. The results are shown in Table 1.

[0109] Table 1

[0110]

[0111]

[0112] It can be seen from Table 1 that by using the high-throughput selective-area diffusion technology to apply the high-throughput selective-area diffusing agent provided by the present invention to the high-throughput selective-area diffusion of NdFeB magnets, a scheme with the highest heavy rare earth utilization efficiency can be obtained under the condition that the coercivity improvement effect meets the requirements. This method is applicable to the production exploration of multiple batches and small batches.

[0113] It can be seen from the comparison between Example 1 and Examples 4 and 5 that when using heavy rare earth metal simple substances or heavy rare earth compounds as raw materials for the high-throughput selective area diffusing agent, compared with using heavy rare earth alloys, the magnetic properties of the obtained NdFeB magnets decrease slightly; it can be seen from the comparison between Example 1 and Example 6 that additive manufacturing can achieve batch design of various printing patterns of the diffusing agent, and it is easy to realize production exploration in multiple batches and small batches; it can be seen from the comparison between Example 1 and Examples 7 and 8 that the diffusion heat treatment is set to be carried out in two stages, and compared with one-stage heat treatment, the magnets have more excellent magnetic properties.

[0114] It can be seen from the comparison between Example 1 and Comparative Examples 1 and 2 that when the particle size of the heavy rare earth spherical powder is relatively small or relatively large, as a raw material for additive manufacturing, it will reduce the printing effect, thereby affecting the magnetic properties of the magnet; it can be seen from the comparison between Example 1 and Comparative Example 3 that when the sphericity of the heavy rare earth spherical powder is too low, its morphology is irregular and the fluidity is poor, and the magnetic properties of the magnet prepared as a raw material for additive manufacturing also decrease.

[0115] In summary, the high-throughput selective area diffusing agent provided by the present invention uses heavy rare earth spherical powders with high sphericity and good fluidity, which are suitable as raw materials for additive manufacturing. By strictly controlling the morphology of the heavy rare earth spherical powders, the comprehensive magnetic properties of the subsequent prepared high-throughput selective area diffusing agent can be significantly improved.

[0116] The high-throughput selective area diffusing agent provided by the present invention is used for high-throughput selective area diffusion of NdFeB magnets. By means of high-throughput selective area dispersion technology combined with additive manufacturing, selective area diffusion is carried out on the surface of the NdFeB magnet. Through subsequent diffusion heat treatment, heavy rare earth elements diffuse into the NdFeB magnet along the molten grain boundary phase, and the coercivity and high-temperature stability of the NdFeB magnet can be greatly improved with less heavy rare earth usage. The high-throughput selective area diffusion method described in the present invention is applicable to production exploration in multiple batches and small batches, and has the characteristics of a high degree of automation in the process flow and a fast R & D cycle.

[0117] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A high-throughput selective area diffusing agent, characterized in that, The high-flux selective diffusing agent is obtained by mixing heavy rare earth spherical powder with a solid organic binder and then melting and processing; The particle size of the heavy rare earth-containing spherical powder is 10-60 μm, and the sphericity is greater than 85%.

2. The high-throughput selected area diffusing agent according to claim 1, wherein, The heavy rare earth-containing spherical powder comprises at least one of a heavy rare earth metal element, a heavy rare earth alloy or a heavy rare earth compound; Preferably, the heavy rare earth metal element includes Tb and Dy; Preferably, the heavy rare earth alloy is an alloy HRE-M, wherein HRE comprises Tb and Dy, and M comprises at least one of Nd, Pr, Ce, La, Al, Cu, Zn, Mg or Ni; Preferably, based on the total mass percentage being 100wt%, in the alloy HRE-M, the mass percentage of HRE is 15-90wt%, and the balance is M; Preferably, the heavy rare earth compound is HRE-X, wherein HRE comprises Tb and Dy, and X comprises F and / or H.

3. The high-throughput selective area diffusing agent according to claim 1 or 2, characterized in that The heavy rare earth-containing spherical powder is prepared by an aerosol method; Preferably, the solid organic binder comprises any one of PVB particles, PVA particles or acrylic resin particles, or a combination of at least two thereof; Preferably, the mass of the solid organic binder is 2-4 wt% of the mass of the heavy rare earth spherical powder; Preferably, the melt processing comprises extrusion or injection molding.

4. The high-throughput selective area diffusing agent according to any one of claims 1-3, characterized in that, Taking the total mass percentage as 100wt%, in the high-flux selective diffusant, the mass percentage of HRE is 15-95wt%, the total mass percentage of C and O is 4.8-20wt%, and the balance is doping components; Preferably, the HRE comprises Tb and Dy in a mass ratio of (0.3-1.7):

1.

5. The high-throughput selective area diffusing agent according to claim 4, wherein The doping component includes at least one of H, F, Nd, Pr, Ce, La, Al, Cu, Zn, Mg or Ni; Preferably, when the doping component contains H, the mass percentage of H is 0.2-1wt%; Preferably, when the doping component contains F, the mass percentage of F is 10-30wt%; Preferably, when the doping component contains Nd, the mass percentage of Nd is 8-60wt%; Preferably, when the doping component contains Pr, the mass percentage of Pr is 8-60wt%; Preferably, when the doping component contains Ce, the mass percentage of Ce is 5-20wt%; Preferably, when the doping component contains La, the mass percentage of La is 5-20wt%; Preferably, when the doping component contains Al, the mass percentage of Al is 1-12 wt%; Preferably, when the doping component contains Cu, the mass percentage of Cu is 4-25wt%; Preferably, when the doping component contains Zn, the mass percentage of Zn is 4-25wt%; Preferably, when the doping component contains Mg, the mass percentage of Mg is 1-10wt%; Preferably, when the doping component contains Ni, the mass percentage of Ni is 2-20wt%.

6. Use of the high-throughput selective area diffusing agent according to any one of claims 1-5, characterized in that, The high-flux selective diffusion agent is used in the high-flux selective diffusion of NdFeB magnets. The high-flux selective diffusion method comprises the following steps: (1) Process the neodymium iron boron magnet to obtain the magnet to be diffused; (2) Design different patterns with a gradient distribution in size, and then print the high-throughput selected-area diffusing agent on the edge area of the pole surface of the magnet to be diffused obtained in step (1) by additive manufacturing to obtain the printed magnet; (3) The printed magnet obtained in step (2) is subjected to diffusion heat treatment to obtain the diffused magnet; the magnetic properties of the obtained diffused magnet are detected to obtain the diffused magnet with the optimal printed pattern.

7. The application according to claim 6, wherein The processing in step (1) includes cutting and grinding; Preferably, the shape of the magnet to be diffused in step (1) includes any one of a prismatic shape, a cylindrical shape or a tile shape.

8. The application according to claim 6 or 7, characterized in that The shape of the unprinted area on the pole surface of the magnet to be diffused in step (2) includes a circle or a square; Preferably, control the interval of the gradient distribution of the diameter of the circle or the side length of the square to be 0.1 - 0.3 mm to obtain the different patterns with a gradient distribution in size.

9. The application according to any one of claims 6-8, characterized in that, The additive manufacturing method in step (2) includes any one of electron beam melting, powder bed fusion, material extrusion or material jetting; Preferably, after printing in step (2), there is also a step of drying at 110 - 130 °C; Preferably, before the diffusion heat treatment in step (3), vacuum pumping and nitrogen purging are repeated; Preferably, the degree of vacuum for the diffusion heat treatment in step (3) < 5×10 -3 Pa.

10. The application according to any one of claims 6-9, characterized in that, The diffusion heat treatment in step (3) includes a first heat treatment and a second heat treatment carried out in sequence; Preferably, the temperature of the first heat treatment is 850 - 950 °C and the time is 3 - 5 h; Preferably, the temperature of the second heat treatment is 450 - 550 °C and the time is 2 - 4 h.

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