CN113948303B - Sintered NdFeB radiation ring and preparation method thereof - Google Patents

Sintered NdFeB radiation ring and preparation method thereof Download PDF

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CN113948303B
CN113948303B CN202111220456.5A CN202111220456A CN113948303B CN 113948303 B CN113948303 B CN 113948303B CN 202111220456 A CN202111220456 A CN 202111220456A CN 113948303 B CN113948303 B CN 113948303B
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powder
ring
lubricant
radiation ring
magnetic powder
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CN113948303A (en
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刘家琴
李磊
吴玉程
刘友好
衣晓飞
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Hefei University of Technology
Earth Panda Advance Magnetic Material Co Ltd
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Hefei University of Technology
Earth Panda Advance Magnetic Material Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0266—Moulding; Pressing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/64—Electric machine technologies in electromobility

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Abstract

The invention belongs to the technical field of permanent magnetic materials, and particularly relates to a sintered NdFeB radiation ring and a preparation method thereof. By proportioning the magnetic powder with different granularity, the coarse powder and the fine powder are reasonably matched, so that the compaction degree of the compact is improved; by nanometer MoS 2 The organic matters are combined to serve as the lubricant, so that the addition amount of the organic lubricant is reduced, the carbon content is effectively reduced, and the coercivity of the magnet is improved; in the isostatic pressing process, a hard tungsten-cobalt alloy is selected as a core mold material to support the radiation ring, so that the shrinkage of the inner diameter and the outer diameter of the radiation ring is consistent in the cold isostatic pressing process; the sintering process is reasonably regulated and controlled, and multistage tempering heat treatment is carried out step by step to eliminate stress and reduce crack rate. The sintered NdFeB radiant ring prepared by the method has the characteristics of excellent magnetic performance, difficult cracking, high yield and good processing performance, and is simple to operate, high in production efficiency and suitable for batch production.

Description

Sintered NdFeB radiation ring and preparation method thereof
Technical Field
The invention belongs to the field of magnetic materials, and particularly relates to a sintered NdFeB radiation ring and a preparation method thereof.
Background
With the development of artificial intelligence and automation technology, the use of finely controlled electromechanical products is increasing, and miniaturization, light weight and high efficiency are the development trend of the motor industry. Compared with the traditional electric excitation motor, the permanent magnet motor has the remarkable advantages of simple structure, small volume, light weight, small loss, high efficiency, high power factor and the like, and is widely applied to various fields of aerospace, national defense and military industry, industrial and agricultural production, daily life and the like.
Currently, most of stator or rotor structures of neodymium iron boron permanent magnet motors are magnetic shoe/strip insertion type or mosaic type: the sintered NdFeB magnetic shoe after magnetizing is inlaid in a frame structure of a soft magnetic material to be spliced into a ring. However, the following problems exist in the mode of splicing the magnetic shoes into a ring: the direction of the magnetic field inside the single-piece magnet is consistent, the magnetic field intensity spliced into a ring by adopting a plurality of magnetic shoes is unevenly distributed along the circle of the excircle, so that the dynamic balance of the spliced magnetic ring is poor, the transition area between magnetic poles is large, the motor generates noise and vibration, and the operation efficiency is reduced. To improve this phenomenon, the angle difference is generally reduced by increasing the number of poles during the production process. However, the number of magnetic poles is increased, and the dimensional machining tolerance of the magnet is more severely required. Because the angle and other processing precision difficulties of the tile-shaped magnet are large, the sizes of different small magnets are different, and the phenomenon of gaps or incomplete splicing can occur during splicing. It is often necessary to first perform a jig-saw process to package the magnets as a group that meets the requirements individually, resulting in a significant increase in installation costs.
The developed neodymium-iron-boron radiation magnetic ring in recent years well overcomes the defects of the spliced magnetic ring, can replace the traditional tile-shaped blocks, and becomes a key new direction of development of neodymium-iron-boron permanent magnet materials. The magnetic field direction of the NdFeB radiation magnetic ring is in a radiation state of continuous distribution by taking the ring center as the center, the magnetic field in the whole magnetic ring is continuously and uniformly distributed, a magnetic pole transition area is not present, the noise and the heat generated by vibration caused by magnetic field jump when the motor operates are greatly reduced, and the operation efficiency of the motor is remarkably improved. The advantages of the magnetic neodymium-iron-boron radiation magnetic ring are mainly embodied in the following aspects: (1) the magnetic conduction frame is not required to be supported and connected, so that the energy density is increased; (2) the complete ring structure avoids falling off and breakage; (3) the original iron core rotor is replaced, so that the motor is smaller in volume, high in rotating speed and easy to control; (4) the motor is more suitable for high-speed and high-precision control motors, has the advantages of high precision, stable operation, low noise and the like, reduces assembly difficulty and time, is an important component for electromechanical development in the future, is very suitable for severe working conditions such as high-speed vibration of electric automobiles, and also provides a guarantee for research and development of novel hub motors and wheel-side motors for vehicles.
However, the existing sintered NdFeB radiant rings have the problems of easy cracking, low toughness and poor processability: firstly, as NdFeB is a brittle material, the tetragonal phase crystal structure is complex, the slippage system is less, the deformation performance is poor, and the maximum deformation amount of a mechanical sample before fracture is less than 1mm; secondly, in the cold isostatic pressing process, the inner diameter and the outer diameter of the radiation ring are inconsistent in shrinkage, and the radiation ring is easy to crush along the radial direction; and thirdly, the sintered NdFeB radiation ring has different thermal expansion coefficients along the radial direction and the axial direction, the thermal expansion causes non-free strain to be generated along the axial direction and the radial direction in the cooling process due to the sealing property of the circular ring, and the circumferential stress is cracked when a large amount of accumulation exceeds the fracture strength of the sintered body in the cooling process.
Chinese patent 201811014250.5 discloses a high-toughness sintered NdFeB radiant ring and a preparation method thereof, and is characterized in that micron-sized PrCu alloy is added into a radiant ring magnet as toughening powder, so that the bending strength and fracture toughness of the radiant ring are improved, and the problem of low yield of the sintered radiant ring is not solved yet.
The Chinese patent 201310753909.X discloses a neodymium-iron-boron radiation orientation ring and a preparation method thereof, which is characterized in that a heavy rare earth alloy is added into a radiation ring magnet to obtain a neodymium-iron-boron radiation ring with excellent magnetic performance, but the problem of low yield of the radiation ring is not solved, and the heavy rare earth alloy is high in price and unfavorable for large-scale production.
The Chinese patent 201610732581.7 provides a preparation method of a radiation orientation sintered neodymium-iron-boron magnetic ring, which is characterized in that the magnetic powder is subjected to two air flow grinding, the lubricant is added twice, the powder fluidity is improved, and a neodymium-iron-boron radiation ring with lower cracking rate is obtained, but the residual carbon content of the magnet is higher, the magnetic performance of the radiation ring is lower, and the applicability is poorer.
Therefore, in order to overcome the above disadvantages, a method for preparing a sintered NdFeB radiant ring is needed, so that the radiant ring has excellent magnetic properties while the yield is high.
Disclosure of Invention
The invention aims to solve the problems of low yield and poor performance of a sintered NdFeB radiant ring, and provides a sintered NdFeB radiant ring and a preparation method thereof.
The technical scheme adopted by the invention for realizing the technical purposes is as follows:
a method for preparing a sintered NdFeB radiant ring, comprising the following steps:
1) Preparing fine powder: carrying out vacuum smelting to obtain NdFeB permanent magnet alloy A, carrying out hydrogen crushing on the alloy A to obtain hydrogen crushing powder B, and carrying out batch jet mill crushing on the hydrogen crushing powder B at different sorting wheel rotating speeds to obtain jet mill powder C1-C4 with different average particle sizes;
2) Regulating granularity: the air-flow grinding powder C1-C4 with different average particle sizes is proportioned according to a certain proportion to obtain the mixed magnetic powder D, coarse powder and fine powder are reasonably matched, the compaction degree of the pressed compact is improved, the shrinkage rate of a radiation ring is reduced, and the residual stress is reduced in the sintering process, so that the mixed magnetic powder D has higher yield.
3) Adding a lubricant: adding nanometer MoS into the mixed magnetic powder D with regulated granularity 2 As an inorganic lubricant, adding a small amount of organic lubricant, and uniformly mixing to obtain mixed magnetic powder E;
4) Orientation molding and cold isostatic pressing: adding the mixed magnetic powder E into a radiation ring die, and performing die pressing in a magnetic field to obtain a green body F; inserting a core mould into the green compact F, vacuum packaging and performing cold isostatic pressing treatment to obtain a radiation ring pressed compact G;
5) Sintering aging: and removing the core mould after the cold isostatic pressing is finished, carrying out vacuum sintering on the radiation ring pressed compact G, filling argon after the sintering is finished, cooling along with a furnace, carrying out air cooling, and carrying out multistage tempering heat treatment to obtain the sintered NdFeB radiation ring.
Further, in step 1), the NdFeB permanent magnet alloy a comprises the following components: (PrNd) x Fe 1-x-y-z M y B z Wherein M is one or more of Al, cu, ga, co, zr, x is more than or equal to 28.5% and less than or equal to 31.5%, y is more than or equal to 0.2% and less than or equal to 2%, z is more than or equal to 0.95% and less than or equal to 1.1%, and the percentages are weight percentages; the conditions of hydrogen breakage are: the permanent magnet alloy A is saturated to absorb hydrogen at room temperature and dehydrogenated at 500-600 ℃ to prepare hydrogen crushing powder; the average particle size of the air-flow milled powder C1-C4 is 1.0-2.0 mu m, 2.0-3.0 mu m, 3.0-4.0 mu m and 4.0-5.0 mu m in sequence.
Further, the mass ratio of the magnetic powder with different particle sizes in the mixed magnetic powder D in the step 2) is as follows: 20% < C1<30%,20% < C2<30%,20% < C3<25%,20% < C4<25%.
Further, in step 3), the nano MoS in the lubricant adding step 2 The addition amount of the powder is 0.5 to 2 percent of the mixed magnetic powder D; the organic lubricant comprises an organic solvent and a lubricant, wherein the mass ratio of the organic solvent to the lubricant is 1-3:1, and the addition amount of the organic lubricant is 0.1% -0.3% of the mixed magnetic powder D.
Preferably, in step 3), the organic solvent is one or more of ethanol, xylene, petroleum ether, acetone, methylene chloride, and n-propanol; the lubricant is one or more of zinc stearate, sodium stearate, lithium stearate, calcium stearate and polytetrafluoroethylene wax.
In step 4), the mixed magnetic powder E after uniform mixing is subjected to radiation orientation molding in a 2T magnetic field, columnar hard tungsten-cobalt alloy with equal height is selected as a core mold material, the diameter of the core mold is 93-97% of the inner diameter of a radiation ring, and after the core mold is inserted into the core part of the radiation ring, cold isostatic pressing treatment of more than 200MPa is carried out.
Further, in step 5), the vacuum sintering process is as follows: sequentially preserving heat for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃, exhausting and presintering, and finally heating to 1020-1080 ℃ for 3-5 h, wherein the heating rate is controlled at 5 ℃/min, argon is cooled to 400-500 ℃ along with the furnace, and then the argon is cooled to room temperature by air cooling.
Further, in step 5), the aging treatment process of the multi-stage tempering heat treatment is as follows: the temperature of the first tempering treatment is 850-950 ℃ and the heat preservation time is 2-3 h, argon is filled after the tempering treatment is finished, the argon is cooled to 200 ℃ along with the furnace, the second tempering is carried out, the temperature is raised to 500-600 ℃, the heat preservation is carried out for 2-3 h, the argon air cooling is carried out to 200 ℃, the third tempering is carried out, the temperature is raised to 300-400 ℃, the heat preservation is carried out for 2-3 h, and finally the argon air cooling is carried out to room temperature.
Compared with the prior art, the invention has the following advantages:
1. through regulating and controlling the granularity of the powder, the coarse powder and the fine powder are reasonably matched, and the fine powder is filled in the gaps of the coarse powder, so that the compactness of the pressed compact is improved, the shrinkage rate of the radiation ring is reduced, and the residual stress is reduced in the sintering process, so that the pressed compact has higher yield.
2. Adding nanometer MoS 2 Can partially replace organic lubricant, reduce the dosage of the organic lubricant and greatly reduce the residual carbon content. In addition, nanometer MoS 2 Has higher melting point, can play roles in inhibiting the growth of crystal grains and refining the crystal grains in a crystal boundary phase, and effectively improves the coercive force of the radiation ring magnet.
3. The hard tungsten-cobalt alloy is selected as a core mould, plays a supporting role in the cold isostatic pressing process and synchronously contracts with the radiation ring, so that the problem of cracking caused by inconsistent contraction of the inner diameter and the outer diameter of the radiation ring is effectively solved, and the sintering yield of the radiation ring is greatly improved.
4. The sintering process is optimized, the cooling process is reasonably controlled, the stress in the radiant ring is reduced, the residual internal stress of the radiant ring is further reduced through multi-step tempering heat treatment, the workability of the radiant ring is improved, and the problem that the sintered NdFeB radiant ring is easy to crack during processing is effectively solved.
Drawings
FIG. 1 is a schematic diagram of a sintering process of a NdFeB radiant ring.
FIG. 2 is a schematic diagram of tempering process of NdFeB radiant rings.
Detailed Description
The present invention will be described in further detail with reference to the following examples, which are intended to facilitate the understanding of the present invention without any limitation thereto.
Example 1:
(1) Vacuum rapid solidification smelting (Pr, nd) 31.5 Fe 65.72 Co 1 Cu 0.2 Al 0.2 Ga 0.2 Zr 0.2 B 0.98 (wt.%) the alloy is saturated to absorb hydrogen at room temperature and dehydrogenated at 550 ℃ to prepare hydrogen crushing powder; and carrying out batch jet mill crushing on the hydrogen crushing powder at different sorting wheel rotating speeds to obtain jet mill powder C1-C4 with different average particle sizes, wherein the average particle sizes of the jet mill powder C1-C4 are sequentially 1.8 mu m, 2.4 mu m, 3.5 mu m and 4.4 mu m.
(2) Proportioning C1-C4, and finally obtaining the powder with the mass ratio of: c1 Mixed magnetic powder of 28%, c2=27%, c3=23%, c4=22%.
(3) Nanometer MoS accounting for 0.5 percent of the total mass is mixed into the mixed magnetic powder 2 As an inorganic lubricant, and a mixture of petroleum ether and sodium stearate in a total mass of 0.2% as an organic lubricant, wherein the mass ratio of petroleum ether to sodium stearate is 1:1, and uniformly mixed.
(4) And (3) placing the uniformly mixed magnetic powder into a rotating magnetic field with the magnetic field strength of 2T for orientation molding, after coating the film, inserting a hard tungsten-cobalt alloy column with the diameter of 93% of the inner diameter of the radiation ring into the core part of the radiation ring as a core mould, and carrying out cold isostatic pressing treatment under 220MPa after vacuum packaging.
(5) And (3) sequentially preserving heat for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃ after cold isostatic pressing, exhausting and presintering, heating to 1060 ℃ and preserving heat for 3h, charging argon gas along with a furnace to cool to 500 ℃ after sintering, and then air-cooling to room temperature to obtain the sintered radiant ring.
(6) Carrying out primary tempering treatment on the sintered radiation ring, keeping the temperature at 900 ℃ for 3 hours, charging argon gas after the completion of the primary tempering treatment, cooling to 200 ℃ along with a furnace, carrying out secondary tempering at 500 ℃ for 2 hours, carrying out air cooling of the argon gas to 200 ℃ after the completion of the secondary tempering treatment, carrying out tertiary tempering at 350 ℃ for 2 hours, and finally carrying out air cooling of the argon gas to room temperature; the finished product radiation ring is manufactured.
Comparative example 1:
(1) Vacuum rapid solidification smelting (Pr, nd) 31.5 Fe 65.72 Co 1 Cu 0.2 Al 0.2 Ga 0.2 Zr 0.2 B 0.98 And (wt.%) the alloy is saturated and absorbed with hydrogen at room temperature, and dehydrogenated at 550 ℃ to obtain hydrogen crushing powder, and the hydrogen crushing powder is subjected to air flow grinding at the same sorting wheel rotation speed to obtain powder with an average particle size of 2.8 mu m.
(2) Nanometer MoS accounting for 0.5 percent of the total mass is doped into the airflow grinding magnetic powder 2 As an inorganic lubricant, and a mixture of petroleum ether and sodium stearate in a total mass of 0.2% as an organic lubricant, wherein the mass ratio of petroleum ether to sodium stearate is 1:1, and uniformly mixed.
(3) And (3) placing the uniformly mixed magnetic powder into a rotating magnetic field with the magnetic field strength of 2T for orientation molding, after coating the film, inserting a hard tungsten-cobalt alloy column with the diameter of 93% of the inner diameter of the radiation ring into the core part of the radiation ring as a core mould, and carrying out cold isostatic pressing treatment under 220MPa after vacuum packaging.
(4) And (3) sequentially preserving heat for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃ after cold isostatic pressing, exhausting and presintering, heating to 1060 ℃ and preserving heat for 3h, charging argon gas along with a furnace to cool to 500 ℃ after sintering, and then air-cooling to room temperature to obtain the sintered radiant ring.
(5) Carrying out primary tempering treatment on the sintered radiation ring, keeping the temperature at 900 ℃ for 3 hours, charging argon gas after the completion of the primary tempering treatment, cooling to 200 ℃ along with a furnace, carrying out secondary tempering at 500 ℃ for 2 hours, carrying out air cooling of the argon gas to 200 ℃ after the completion of the secondary tempering treatment, carrying out tertiary tempering at 350 ℃ for 2 hours, and finally carrying out air cooling of the argon gas to room temperature; the finished product radiation ring is manufactured.
Example 2:
(1) Vacuum rapid solidification smelting (Pr, nd) 31 Fe 66.22 Co 1 Cu 0.2 Al 0.2 Ga 0.2 Zr 0.2 B 0.98 (wt.%) the alloy is saturated to absorb hydrogen at room temperature and dehydrogenated at 560 ℃ to obtain hydrogen crushing powder; and (3) carrying out jet mill grinding on the hydrogen crushing powder at different rotating speeds of the sorting wheel to obtain jet mill powder C1-C4 with different average particle sizes, wherein the average particle sizes of the jet mill powder C1-C4 are sequentially 1.3 mu m, 2.7 mu m, 3.4 mu m and 4.2 mu m.
(2) Proportioning C1-C4, and finally obtaining the powder with the mass ratio of: c1 Mixed magnetic powder of =25%, c2=27%, c3=24%, and c4=24%.
(3) Nanometer MoS accounting for 0.8 percent of the total mass is mixed into the mixed magnetic powder 2 As an inorganic lubricant, and a mixture of petroleum ether and zinc stearate in a total mass of 0.2% as an organic lubricant, wherein the mass ratio of petroleum ether to zinc stearate is 1.5:1, and uniformly mixed.
(4) And (3) placing the uniformly mixed magnetic powder into a rotating magnetic field with the magnetic field strength of 2T for orientation molding, after coating the film, inserting a hard tungsten-cobalt alloy column with the diameter of 94% of the inner diameter of the radiation ring into the core part of the radiation ring as a core mould, and carrying out cold isostatic pressing treatment under 220MPa after vacuum packaging.
(5) And (3) sequentially preserving heat for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃ after cold isostatic pressing, exhausting and presintering, heating to 1050 ℃ and preserving heat for 3h, charging argon gas along with a furnace to cool to 450 ℃ after sintering, and then air-cooling to room temperature to obtain the sintered radiant ring.
(6) Carrying out primary tempering treatment on the sintered radiation ring, wherein the temperature is 880 ℃, the heat preservation is carried out for 3 hours, argon is filled after the completion of the primary tempering treatment, the temperature is 550 ℃, the heat preservation is carried out for 2 hours, the argon is cooled to 200 ℃ after the completion of the primary tempering treatment, the temperature is 350 ℃, the heat preservation is carried out for 2 hours, and finally the argon is cooled to room temperature; the finished product radiation ring is manufactured.
Comparative example 2:
(1) The same magnetic powder as in example 2 was selected, and the distribution of the magnetic powder after proportioning was also the same as in example 2.
(2) The mixture of petroleum ether and zinc stearate accounting for 0.2 percent of the total mass is mixed into the mixed magnetic powder to be used as an organic lubricant, wherein the mass ratio of the petroleum ether to the zinc stearate is 1.5:1, and the petroleum ether and the zinc stearate are uniformly mixed.
(3) And (3) placing the uniformly mixed magnetic powder into a rotating magnetic field with the magnetic field strength of 2T for orientation molding, after coating the film, inserting a hard tungsten-cobalt alloy column with the diameter of 94% of the inner diameter of the radiation ring into the core part of the radiation ring as a core mould, and carrying out cold isostatic pressing treatment under 220MPa after vacuum packaging.
(4) And (3) sequentially preserving the heat of the formed pressed compact for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃, exhausting and presintering, heating to 1050 ℃ and preserving the heat for 3h, charging argon gas along with the furnace to cool to 450 ℃ after sintering, and then air-cooling to room temperature to obtain the sintered radiant ring.
(5) Carrying out primary tempering treatment on the sintered radiation ring at 880 ℃, preserving heat for 3 hours, cooling argon to 200 ℃ after the completion of the primary tempering treatment, carrying out secondary tempering at 550 ℃ and preserving heat for 2 hours, cooling argon to 200 ℃ after the completion of the primary tempering treatment, carrying out tertiary tempering at 350 ℃ and preserving heat for 2 hours, and finally cooling argon to room temperature; the finished product radiation ring is manufactured.
Example 3:
(1) Vacuum rapid solidification smelting (Pr, nd) 30.5 Fe 66.72 Co 1 Cu 0.2 Al 0.2 Ga 0.2 Zr 0.2 B 0.98 (wt.%) the alloy is saturated to absorb hydrogen at room temperature and dehydrogenated at 580 ℃ to produce hydrogen crushing powder; and (3) carrying out jet mill grinding on the hydrogen crushing powder at different rotating speeds of the sorting wheel to obtain jet mill powder C1-C4 with different average particle sizes, wherein the average particle sizes of the jet mill powder C1-C4 are sequentially 1.5 mu m, 2.6 mu m, 3.9 mu m and 4.7 mu m.
(2) Proportioning C1-C4, and finally obtaining the powder with the mass ratio of: c1 Mixed magnetic powder of =26%, c2=26%, c3=24%, and c4=24%.
(3) Nanometer MoS accounting for 1.2 percent of the total mass is mixed into the mixed magnetic powder 2 As an inorganic lubricant, and a mixture of acetone and lithium stearate with a total mass of 0.2% as an organic lubricant, wherein the mass ratio of acetone to lithium stearate is 2:1, and uniformly mixed.
(4) And (3) placing the uniformly mixed magnetic powder into a rotating magnetic field with the magnetic field strength of 2T for orientation molding, after coating the film, inserting a hard tungsten-cobalt alloy column with the diameter of 95% of the inner diameter of the radiation ring into the core part of the radiation ring as a core mould, and carrying out cold isostatic pressing treatment under 220MPa after vacuum packaging.
(5) And (3) sequentially preserving heat for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃ after cold isostatic pressing, exhausting and presintering, heating to 1055 ℃ and preserving heat for 3h, charging argon gas along with the furnace after sintering, cooling to 450 ℃ and then cooling to room temperature to obtain the sintered radiant ring.
(6) Carrying out primary tempering treatment on the sintered radiation ring, wherein the temperature is 880 ℃, the heat preservation is carried out for 3 hours, argon is filled after the completion of the primary tempering treatment, the temperature is 550 ℃, the heat preservation is carried out for 2 hours, the argon is cooled to 200 ℃ after the completion of the primary tempering treatment, the temperature is 350 ℃, the heat preservation is carried out for 2 hours, and finally the argon is cooled to room temperature; the finished product radiation ring is manufactured.
Comparative example 3:
(1) The same magnetic powder as in example 3 was selected, and the distribution of the magnetic powder after proportioning was also the same as in example 3.
(2) Nanometer MoS accounting for 1.2 percent of the total mass is mixed into the mixed magnetic powder 2 As an inorganic lubricant, and a mixture of acetone and lithium stearate with a total mass of 0.2% as an organic lubricant, wherein the mass ratio of acetone to lithium stearate is 2:1, and uniformly mixed.
(3) And (3) placing the uniformly mixed magnetic powder into a rotating magnetic field with the magnetic field strength of 2T for orientation molding, inserting an iron column with the diameter of 95% of the inner diameter of the radiation ring into the core part of the radiation ring after coating the film, taking the iron column as a core mould, and carrying out 220MPa cold isostatic pressing treatment after vacuum packaging.
(4) And (3) sequentially preserving heat for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃ after cold isostatic pressing, exhausting and presintering, heating to 1055 ℃ and preserving heat for 3h, charging argon gas along with the furnace after sintering, cooling to 450 ℃ and then cooling to room temperature to obtain the sintered radiant ring.
(5) Carrying out primary tempering treatment on the sintered radiation ring, wherein the temperature is 880 ℃, the heat preservation is carried out for 3 hours, argon is filled after the completion of the primary tempering treatment, the temperature is 550 ℃, the heat preservation is carried out for 2 hours, the argon is cooled to 200 ℃ after the completion of the primary tempering treatment, the temperature is 350 ℃, the heat preservation is carried out for 2 hours, and finally the argon is cooled to room temperature; the finished product radiation ring is manufactured.
Example 4:
(1) Vacuum rapid solidification smelting (Pr, nd) 30 Fe 67.22 Co 1 Cu 0.2 Al 0.2 Ga 0.2 Zr 0.2 B 0.98 (wt.%) the alloy is saturated to absorb hydrogen at room temperature and dehydrogenated at 575 ℃ to prepare hydrogen crushing powder; and (3) carrying out jet mill grinding on the hydrogen crushing powder at different rotating speeds of the sorting wheel to obtain jet mill powder C1-C4 with different average particle sizes, wherein the average particle sizes of the jet mill powder C1-C4 are sequentially 1.3 mu m, 2.2 mu m, 3.5 mu m and 4.3 mu m.
(2) Proportioning C1-C4, and finally obtaining the powder with the mass ratio of: c1 Mixed magnetic powder of 28%, c2=24%, c3=24%, and c4=24%.
(3) Nanometer MoS accounting for 1.5 percent of the total mass is mixed into the mixed magnetic powder 2 As an inorganic lubricant, and a mixture of n-propanol and calcium stearate in an amount of 0.2% by mass in total, wherein the mass ratio of n-propanol to calcium stearate is 2.5:1, was used as an organic lubricant, and uniformly mixed.
(4) And (3) placing the uniformly mixed magnetic powder into a rotating magnetic field with the magnetic field strength of 2T for orientation molding, after coating the film, inserting a hard tungsten-cobalt alloy column with the diameter of 96% of the inner diameter of the radiation ring into the core part of the radiation ring as a core mould, and carrying out 225MPa cold isostatic pressing treatment after vacuum packaging.
(5) And (3) sequentially preserving heat for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃ after cold isostatic pressing, exhausting and presintering, heating to 1065 ℃ and preserving heat for 3h, charging argon gas along with a furnace to cool to 480 ℃ after sintering, and then air-cooling to room temperature to obtain the sintered radiant ring.
(6) Carrying out primary tempering treatment on the sintering state radiation ring, wherein the temperature is 920 ℃, the heat preservation is carried out for 3 hours, argon is filled after the completion of the primary tempering treatment, the temperature is 570 ℃, the heat preservation is carried out for 2 hours, the argon is cooled to 220 ℃ after the completion of the primary tempering treatment, the temperature is 380 ℃, the heat preservation is carried out for 2 hours, and finally the argon is cooled to the room temperature; the finished product radiation ring is manufactured.
Comparative example 4:
(1) The same magnetic powder as in example 4 was selected, and the distribution of the magnetic powder after proportioning was also the same as in example 4.
(2) Nanometer MoS accounting for 1.5 percent of the total mass is mixed into the mixed magnetic powder 2 As an inorganic lubricant, and a mixture of n-propanol and calcium stearate in an amount of 0.2% by mass in total, wherein the mass ratio of n-propanol to calcium stearate is 2.5:1, was used as an organic lubricant, and uniformly mixed.
(3) And (3) placing the uniformly mixed magnetic powder into a rotating magnetic field with the magnetic field strength of 2T for orientation molding, after coating the film, inserting a hard tungsten-cobalt alloy column with the diameter of 96% of the inner diameter of the radiation ring into the core part of the radiation ring as a core mould, and carrying out 225MPa cold isostatic pressing treatment after vacuum packaging.
(4) And (3) sequentially preserving heat of the pressed compact after cold isostatic pressing at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃ for 1h, exhausting and presintering, heating to 1065 ℃ and preserving heat for 3h, and filling argon gas after sintering, and cooling to room temperature to obtain the sintered radiant ring.
(5) Carrying out primary tempering treatment on the sintering state radiation ring, wherein the temperature is 920 ℃, the heat preservation is carried out for 3 hours, argon is filled after the completion of the primary tempering treatment, the temperature is 570 ℃, the heat preservation is carried out for 2 hours, the argon is cooled to 220 ℃ after the completion of the primary tempering treatment, the temperature is 380 ℃, the heat preservation is carried out for 2 hours, and finally the argon is cooled to the room temperature; the finished product radiation ring is manufactured.
Example 5:
(1) Vacuum rapid solidification smelting (Pr, nd) 29.5 Fe 67.72 Co 1 Cu 0.2 Al 0.2 Ga 0.2 Zr 0.2 B 0.98 (wt.%) the alloy is saturated to absorb hydrogen at room temperature and dehydrogenated at 565 ℃ to produce hydrogen crushed powder; and (3) carrying out jet mill grinding on the hydrogen crushing powder at different rotating speeds of the sorting wheel to obtain jet mill powder C1-C4 with different average particle sizes, wherein the average particle sizes of the jet mill powder C1-C4 are sequentially 1.4 mu m, 2.5 mu m, 3.4 mu m and 4.7 mu m.
(2) Proportioning C1-C4, and finally obtaining the powder with the mass ratio of: c1 Mixed magnetic powder of 27%, c2=26%, c3=23%, c4=24%.
(3) Nanometer MoS accounting for 2 percent of the total mass is mixed in the mixed magnetic powder 2 As an inorganic lubricant, and a mixture of n-propanol and calcium stearate in an amount of 0.2% by mass in total, wherein the mass ratio of n-propanol to calcium stearate is 3:1, was used as an organic lubricant, and uniformly mixed.
(4) And (3) placing the uniformly mixed magnetic powder into a rotating magnetic field with the magnetic field strength of 2T for orientation molding, after coating the film, inserting a hard tungsten-cobalt alloy column with the diameter of 97% of the inner diameter of the radiation ring into the core part of the radiation ring as a core mould, and carrying out 225MPa cold isostatic pressing treatment after vacuum packaging.
(5) And (3) sequentially preserving heat for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃ after cold isostatic pressing, exhausting and presintering, heating to 1065 ℃ and preserving heat for 3h, charging argon gas along with a furnace to cool to 480 ℃ after sintering, and then air-cooling to room temperature to obtain the sintered radiant ring.
(6) Carrying out primary tempering treatment on the sintered radiation ring, wherein the temperature is 930 ℃, preserving heat for 3 hours, charging argon gas after finishing, cooling to 200 ℃ along with a furnace, carrying out secondary tempering, wherein the temperature is 560 ℃, preserving heat for 2 hours, cooling the argon gas to 220 ℃ after finishing, carrying out tertiary tempering, preserving heat for 2 hours at 380 ℃, and finally cooling the argon gas to room temperature; the finished product radiation ring is manufactured.
Comparative example 5:
(1) The same magnetic powder as in example 5 was selected, and the distribution of the magnetic powder after proportioning was also the same as in example 5.
(2) Nanometer MoS accounting for 2 percent of the total mass is mixed in the mixed magnetic powder 2 As an inorganic lubricant, and a mixture of n-propanol and calcium stearate in an amount of 0.2% by mass in total, wherein the mass ratio of n-propanol to calcium stearate is 3:1, was used as an organic lubricant, and uniformly mixed.
(3) And (3) placing the uniformly mixed magnetic powder into a rotating magnetic field with the magnetic field strength of 2T for orientation molding, after coating the film, inserting a hard tungsten-cobalt alloy with the diameter of 97% of the inner diameter of the radiation ring into the core part of the radiation ring as a core mold, and carrying out 225MPa cold isostatic pressing treatment after vacuum packaging.
(4) And (3) sequentially preserving heat for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃ after cold isostatic pressing, exhausting and presintering, heating to 1065 ℃ and preserving heat for 3h, charging argon gas along with a furnace to cool to 480 ℃ after sintering, and then air-cooling to room temperature to obtain the sintered radiant ring.
(5) And (3) carrying out primary tempering treatment on the sintered radiant ring at 930 ℃ for 3 hours, carrying out argon air cooling to room temperature after the completion of the primary tempering treatment, carrying out secondary tempering at 560 ℃ for 2 hours, and carrying out argon air cooling to room temperature after the completion of the secondary tempering treatment, so as to obtain the finished radiant ring.
A multi-batch test was performed according to examples 1 to 5 and comparative examples 1 to 5, and the results were as follows:
Figure GDA0004137631770000101
Figure GDA0004137631770000111
from the results given in the table above, it can be seen that: the sintered NdFeB radiant ring prepared by the technology has very high sintering yield and processing yield, effectively reduces the defective rate and cost of the sintered NdFeB radiant ring, has excellent magnetic performance, and is suitable for mass production.
The foregoing is merely illustrative of the preferred embodiments of the present invention and is not intended to limit the embodiments and scope of the present invention, and it should be appreciated by those skilled in the art that equivalent substitutions and obvious variations may be made using the teachings of the present invention, and all such variations are intended to be included within the scope of the present invention.

Claims (8)

1. A preparation method of a sintered NdFeB radiation ring is characterized by comprising the following steps: the method comprises the following steps:
1) Preparing fine powder: carrying out vacuum melting to obtain NdFeB permanent magnet alloy A, carrying out hydrogen crushing on the alloy A to obtain hydrogen crushing powder B, and carrying out batch jet mill crushing on the hydrogen crushing powder B at different sorting wheel rotating speeds to obtain jet mill powder C1-C4 with different average particle sizes;
the NdFeB permanent magnet alloy A comprises the following components: (PrNd) x Fe 1-x-y-z M y B z Wherein M is one or more of Al, cu, ga, co, zr, x is more than or equal to 28.5% and less than or equal to 31.5%, y is more than or equal to 0.2% and less than or equal to 2%, and z is more than or equal to 0.95% and less than or equal to 1.1%;
2) Regulating granularity: mixing the air-flow grinding powder C1-C4 with different average particle sizes according to a certain proportion to obtain mixed magnetic powder D;
3) Adding a lubricant: adding nanometer MoS into the mixed magnetic powder D with regulated granularity 2 As an inorganic lubricant, adding an organic lubricant, and uniformly mixing to obtain mixed magnetic powder E; the addition amount of the organic lubricant is 0.1% -0.3% of the mixed magnetic powder D;
4) Orientation molding and cold isostatic pressing: adding the mixed magnetic powder E into a radiation ring die, and performing die pressing in a magnetic field to obtain a green body F; inserting a core mould into the green compact F, vacuum packaging and performing cold isostatic pressing treatment to obtain a radiation ring pressed compact G;
5) Sintering aging: and removing the core mould after the cold isostatic pressing is finished, and carrying out vacuum sintering on the radiation ring pressed compact G, wherein the vacuum sintering process comprises the following steps: sequentially carrying out heat preservation for 1h at 350 ℃, 500 ℃, 650 ℃, 820 ℃ and 980 ℃, exhausting and presintering, and finally heating to 1020-1080 ℃ and preserving heat for 3-5 h, wherein the heating rate is controlled at 5 ℃/min, argon is cooled to 400-500 ℃ along with a furnace, and then argon is air-cooled to room temperature, so that the sintered NdFeB radiant ring is obtained.
2. The method according to claim 1, wherein the conditions for hydrogen cracking in step 1) are: the permanent magnet alloy A is saturated to absorb hydrogen at room temperature and dehydrogenated at 500-600 ℃ to prepare hydrogen crushing powder; the average particle size of the airflow flour C1-C4 is 1.0-2.0 mu m, 2.0-3.0 mu m, 3.0-4.0 mu m and 4.0-5.0 mu m in sequence.
3. The method according to claim 1, wherein the mass ratio of the magnetic powder of different particle sizes in the mixed magnetic powder D in the particle size adjusting step satisfies: 20% < C1<30%,20% < C2<30%,20% < C3<25%,20% < C4<25%.
4. The method of claim 1, wherein the nano MoS in the lubricant adding step 2 The addition amount of the powder is 0.5% -2% of the mixed magnetic powder D; the organic lubricant comprises an organic solvent and a lubricant, wherein the mass ratio of the organic solvent to the lubricant is 1-3:1.
5. The preparation method according to claim 4, wherein the organic solvent is one or more of ethanol, xylene, petroleum ether, acetone, methylene chloride and n-propanol; the lubricant is one or more of zinc stearate, sodium stearate, lithium stearate, calcium stearate and polytetrafluoroethylene wax.
6. The method according to claim 1, wherein in the steps of orientation molding and cold isostatic pressing, the mixed magnetic powder E after being uniformly mixed is subjected to radiation orientation molding in a 2T magnetic field, a columnar hard tungsten-cobalt alloy with the same height is selected as a mandrel material, the diameter of the mandrel is 93-97% of the inner diameter of the radiation ring, and after the mandrel is inserted into the core of the radiation ring, cold isostatic pressing treatment of 200MPa or more is performed.
7. The method according to claim 1, wherein in step 5), the aging process of the multi-stage tempering heat treatment is: the temperature of the primary tempering treatment is 850-950 ℃ and the heat preservation time is 2-3 h, argon is filled after the primary tempering treatment is finished, the primary tempering treatment is carried out after argon is filled into the furnace and cooled to 200 ℃, the secondary tempering treatment is carried out, the temperature is raised to 500-600 ℃, the heat preservation is carried out for 2-3 h, the argon air cooling is carried out to 200 ℃, the tertiary tempering treatment is carried out, the temperature is raised to 300-400 ℃, the heat preservation is carried out for 2-3 h, and finally the argon air cooling is carried out to the room temperature.
8. A sintered NdFeB radiant ring prepared according to the method of any one of claims 1-7.
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