CN117012538B - Preparation process of neodymium-iron-boron magnet based on waste recovery - Google Patents
Preparation process of neodymium-iron-boron magnet based on waste recovery Download PDFInfo
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- CN117012538B CN117012538B CN202311280262.3A CN202311280262A CN117012538B CN 117012538 B CN117012538 B CN 117012538B CN 202311280262 A CN202311280262 A CN 202311280262A CN 117012538 B CN117012538 B CN 117012538B
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- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- 238000011084 recovery Methods 0.000 title description 6
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- 238000004064 recycling Methods 0.000 claims abstract description 21
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- 238000000227 grinding Methods 0.000 claims abstract description 14
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- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 14
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 13
- 238000001816 cooling Methods 0.000 claims abstract description 12
- 239000010949 copper Substances 0.000 claims description 27
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Classifications
-
- 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
-
- 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
- H01F41/0293—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 diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
-
- 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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Hard Magnetic Materials (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
Abstract
The invention belongs to the field of magnet preparation, and particularly relates to a preparation process of a neodymium iron boron magnet based on waste recycling. The preparation process comprises the following steps: 1) Pretreating the waste, and then taking rare earth copper powder and ZrO 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder; 2) And (3) placing the mixed powder in the step (1) in a mould for orientation, profiling, sintering, tempering and cooling to obtain the NdFeB magnet. According to the invention, the neodymium-iron-boron magnet raw material is efficiently recovered from the waste material, waste of the waste material is avoided, the cheaper rare earth is used to enable the outer layer of the magnet crystal grain to form an Nd-rich phase, the magnet cost is reduced, and in addition, the neodymium-iron-boron magnet prepared by the invention has good coercivity, remanence, magnetic energy and high temperature resistance.
Description
Technical Field
The invention belongs to the field of magnet preparation, and particularly relates to a preparation process of a neodymium iron boron magnet based on waste recycling.
Background
The neodymium-iron-boron magnet is the most rapidly developed, widely applied, highest in cost performance and optimal in comprehensive performance, china is the largest country for producing the rare-earth magnet material, the explosive development of the magnetic material industry leads to the rising of the price of neodymium, but the domestic neodymium-iron-boron permanent magnet material presents the phenomena of surplus low-end productivity and insufficient high-end productivity, and the demand for the neodymium-iron-boron magnet with high comprehensive performance is continuously rising. Along with the updating of instrument and equipment, a large amount of neodymium iron boron magnet waste materials are generated, the brittleness of the neodymium iron boron magnet waste materials is high, a lot of waste materials are easily generated during processing, the production cost is increased, serious pollution is caused to the environment, in addition, rare earth resources are non-renewable resources, and the recycling of the neodymium iron boron magnet from the waste materials is necessary in the aspects of economic benefit, environmental protection, resource conservation and the like. Current methods for recovering neodymium-iron-boron magnets from scrap: firstly, smelting waste, adding neodymium-iron-boron powder for mixing, and remanufacturing a neodymium-iron-boron magnet, secondly, after crushing the waste, testing the components of the waste, adding the neodymium-iron-boron powder for airflow grinding, pressing and sintering, and remanufacturing the neodymium-iron-boron magnet; however, these methods have poor recovery and waste non-renewable resources to a great extent.
The neodymium-iron-boron magnet is divided into a bonding type, a hot-pressing type and a sintering type, and the density of the bonding type neodymium-iron-boron magnet is generally only 80% of theoretical due to the fact that a large amount of adhesive is added, so that the bonding type neodymium-iron-boron magnet is weaker than the sintering type neodymium-iron-boron magnet in magnetic performance, and the bonding type neodymium-iron-boron magnet is an isotropic magnet and has the same magnetism in all directions, so that a multipolar integral magnet is conveniently manufactured, but the magnetic performance, coercive force and working temperature are low; under the condition that the hot-pressed neodymium-iron-boron magnet is basically free from using medium and heavy rare earth, extremely high magnetic performance can be realized, the loss in the processing process is low, but the hot-pressed neodymium-iron-boron magnet can only be made into a ring shape at present, so that the application range of the hot-pressed neodymium-iron-boron magnet is limited to a great extent, the hot-pressed neodymium-iron-boron technology has high barrier and high price; the sintered NdFeB magnet of the main stream product has extremely high magnetic performance and is a magnetic material with the best magnetic performance at present, but the sintered NdFeB magnet still has the defects of low material utilization rate, difficult processing, poor stability, poor corrosion resistance and easy deformation.
Disclosure of Invention
In order to solve the performance defects of the existing neodymium-iron-boron magnet, such as low material utilization rate, difficult processing, poor stability and poor corrosion resistance, the invention provides a preparation process of the neodymium-iron-boron magnet based on waste recycling in the aspects of economic benefit, environmental protection, resource conservation and the like.
The invention aims at:
(1) The neodymium-iron-boron magnet can be efficiently recovered from the waste, so that the dosage of neodymium element is reduced, the resources are saved, and the cost is reduced;
(2) The chemical stability and the corrosion resistance of the NdFeB magnet are ensured;
(3) The performance of the NdFeB magnet can be improved, and the coercive force of the magnet can be improved.
A preparation process of neodymium-iron-boron magnet based on waste recovery,
the preparation process comprises the following steps:
1) Pretreating the waste, and then taking rare earth copper powder and ZrO 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder;
2) And (3) placing the mixed powder in the step (1) in a mould for orientation, profiling, sintering, tempering and cooling to obtain the NdFeB magnet.
As a preferred alternative to this,
the pretreatment step of the step 1) comprises the steps of cleaning and drying, and crushing the waste materials to 60-200 meshes after drying;
step 1) the waste material is Nd with high-temperature failure 2 Fe 14 Waste material of B neodymium-iron-boron magnet and before failure of neodymium-iron-boron magnetThe residual magnetic strength is more than or equal to 1.16 and T, and the residual magnetic strength after failure is less than or equal to 0.90 and T.
As a preferred alternative to this,
the mesh number of the rare earth copper powder in the step 1) is 100-200 meshes, and the components are La-Cu and/or Ce-Cu and/or Pr-Cu and/or Gd-Cu and/or Ho-Cu and/or Tb-Cu and/or Dy-Cu.
As a preferred alternative to this,
the mesh number of the ZrO2 in the step 1) is 200-400 mesh.
As a preferred alternative to this,
the mixed powder in the step 1) contains 5 to 10 percent wt percent of rare earth copper powder and ZrO 2 10-15 percent wt percent and the balance of waste powder.
As a preferred alternative to this,
the strength of the orientation magnetic field in the step 2) is 1.2-1.35T, and the orientation time is 25-30 min.
As a preferred alternative to this,
and 2) pressing the compression mould at the pressure of 200-240 Mpa.
As a preferred alternative to this,
the sintering in the step 2) is carried out in a non-nitrogen protective atmosphere or a vacuum atmosphere, 4 to 6 h are sintered at the temperature of 900 to 1050 ℃, and then the temperature is kept at the temperature of 700 to 900 ℃ for 1 to 3 h.
As a preferred alternative to this,
and 2) oil quenching is carried out before tempering by 0.5-1 h, and tempering is carried out by 8-12 h at the temperature of 400-480 ℃.
When the existing neodymium-iron-boron magnet is applied to an environment with the temperature of more than 180 ℃, a magnetic Nd compound (R phase component) and Nd are subjected to disordered thermal diffusion, the intrinsic coercivity of the magnet is rapidly reduced along with the temperature rise, the irreversible loss of magnetic flux of the neodymium-iron-boron magnet at a higher temperature is greatly increased, and therefore the magnetic performance is reduced and even the magnetism is lost. NdFeB expands along grain boundary and generates crack during hydrogen crushing, zrO during jet milling 2 Stress is generated on grain boundary of waste materials, zr 4+ Cu is added with 2+ The crystal grain boundary is broken by introducing the crystal grain boundary into the cavity of the tetragonal system of the magnet in a cavity type doping mode, so that the particles are broken by crystal grain penetration, larger crystals are broken into more dispersed crystal grains, the waste particles are distributed more uniformly and continuously,and can be effectively reoriented.
In addition, the choice of waste material will also have a certain impact on the process of the invention. Firstly, the original performance of the waste, namely the residual magnetic strength of the waste before failure, the original residual magnetic performance of the waste determines the original magnetic crystal form and quality, if the original residual magnetic strength is lower, the R-M-B three phases in the original magnetic body are mostly in poor coordination, or the R phase and the M phase are reduced and the B phase are more due to component proportioning reasons or processing technology reasons, so that the actual failure reasons of the waste are possibly magnetic crystal distortion caused by B phase diffusion or secondary growth, macroscopic magnetism is weakened due to residual magnetic deviation, and the diffused or grown B phase has a certain pinning effect, so that the reorientation effect is weakened, and the failure NdFeB magnetic waste with better original quality is selected, and the technological effect of the invention can be ensured relatively more stably. Secondly, the remanence of the waste is also one of the factors which are important in influencing the effect of the method of the invention, because as mentioned above, the weakening of the magnetism caused by B-phase diffusion or secondary growth generally hardly causes the remanence of a magnet with better quality to be reduced below 1.02T, because the remanence does not damage the magnetic phases (namely R phase and M phase) excessively, and the remanence of the waste is obviously reduced to less than or equal to 0.9T, which means that the unordered diffusion of the magnetic phases and unordered diffusion of Nd elements existing in the waste basically can be determined, the requirement of the invention on the state of the waste can be met, and the rearrangement of R phase and the directional construction of Nd can be conveniently realized to form new R phase components.
In addition, the rare earth copper powder adopted by the invention needs to control the mesh number, because the surface of the sintered magnet is damaged due to the larger mesh number, so that the magnetic property of the sintered magnet is reduced, the mixing effect is affected by the small mesh number, the components are easy to segregate, and the performance of the sintered magnet is affected. The magnetic force inside the magnet generates attractive force when the magnet is oriented, the used rare earth copper powder interacts with Nd and competes with the Nd, the molecular motion of the magnet is aggravated after the magnet is heated, copper promotes the rare earth element to enter the crystal lattice to form solid solution, meanwhile, the dislocation motion speed of the crystal boundary is quickened, namely, the rare earth copper powder promotes the deformability of the crystal boundary, so that the easy magnetization axis of the neodymium-iron-boron magnet is orderly arranged along the orientation direction, and higher magnetic performance is realized. The addition of the rare earth copper powder is favorable for reconstructing grain boundaries, forming new grain boundaries to isolate adjacent grains, weakening the magnetic coupling effect among tetragonal grains, inhibiting the growth of grains with inverse magnetic domains, and preventing the expansion of grains with inverse magnetic domains, so that magnetic crystals with high anisotropism are generated on the surface of the magnet, the anisotropic field of the local magnetic crystals is enhanced, the effect of attracting the domains is achieved, the dynamic pinning center is realized, the displacement of domain walls is limited, and the stability of the magnet is improved. In addition, the addition of the rare earth copper powder adjusts the proportion of raw materials in the waste powder, namely, the use amount of low-cost rare earth is improved, the use amount of neodymium is reduced, and the magnet cost is reduced, wherein the Cu has high chemical stability, the electrode potential is 2.8V higher than Nd, and replaces part of Nd with low potential, so that a high potential new grain boundary phase is formed in the system, the potential difference between the rare earth copper powder and a tetragonal system magnet is reduced, and the corrosion resistance of the neodymium-iron-boron magnet is enhanced.
In the invention, rare earth is activated by rapid temperature rise during high-temperature sintering, and part of pores are filled with rare earth copper powder, so that the refractoriness of the magnet is slightly improved, and the magnet still has extremely high thermal stability above the original working limit temperature. The magnet is homogenized by constant temperature treatment for a period of time after high-temperature sintering, so that the tempered magnet has good magnetic performance and low loss of high Wen Citong, and the large temperature gradient of each part of the magnet is avoided, thereby avoiding the cracking of the magnet during processing.
In the technical scheme of the invention, the other core is a tempering process. Firstly, the oil quenching reaction process is milder, the temperature can be accurately controlled, compared with the water quenching heat conduction rate, the magnet is more uniform, the formation of cold quenching lines is reduced, the possibility of cracking of the magnet is reduced, and the air can be isolated to prevent surface oxidation. In the tempering process, the high-temperature liquid phase existing at the edges of the crystal grains is subjected to phase transformation, the eutectic product contains more Fe, the magnet with high Fe content tends to generate rare earth-Fe components with higher melting point, nd atoms penetrate into the crystal boundary in the process to form continuous Nd-rich phases, surface defects are filled, so that the intrinsic coercivity of the magnet is further improved, and the magnet absorbs a large amount of fracture energy due to the volume effect generated by the phase transformation in the magnet, so that the magnet has better toughness.
In the range of the invention, the intrinsic coercivity of the sample after tempering at the temperature (400 ℃) which is higher than the lowest eutectic point temperature of the magnet is improved, the improvement amplitude of the intrinsic coercivity is reduced along with the increase of the tempering temperature, and the research shows that the magnet with small residual magnetism change can be obtained when the tempering temperature is 460 ℃. However, when the tempering temperature is lower than the eutectic transition temperature of the magnet, nd-rich phases serving as sources for forming thin-layer grain boundary phases tend to agglomerate, the utilization rate of the Nd-rich phases is affected by the existence of massive Nd-rich phases, adjacent neodymium-iron-boron grains can be effectively isolated only when the Nd-rich phases are continuously distributed along the grain boundaries of the main phases, the neodymium-iron-boron grains are demagnetized and exchange-coupled, reverse magnetization domain nuclei are not easy to form between the neodymium-iron-boron grains, and meanwhile, the propagation of reverse magnetic domains is effectively blocked, so that the intrinsic coercivity of the magnet is improved, the displacement of domain walls is not hindered by the loss of the inter-crystal thin-layer Nd phases, and the reverse magnetization of one grain drives the reverse magnetization of other grains. In addition, the tempering temperature is too high or the quenching speed is too high, along with the increase and extension of gaps, the stray field in the magnet is increased, gaps which are not filled by Nd-rich phases appear in the crystal boundary, magnetic poles perpendicular to the c axis appear in the microscopic regions, and the reverse microscopic demagnetizing field exists in the regions, so that the magnetic performance is reduced.
The invention has the advantages that:
(1) According to the invention, the neodymium iron boron magnet raw material is efficiently recovered from the waste material, so that waste of the waste material is avoided;
(2) The invention uses cheaper rare earth to lead the outer layer of the magnet crystal grain to form Nd-rich phase, thereby reducing the magnet cost;
(3) The neodymium-iron-boron magnet prepared by the invention has better coercivity, remanence, magnetic energy product and high temperature resistance.
Detailed Description
The present invention will be described in further detail with reference to specific examples. Those of ordinary skill in the art will be able to implement the invention based on these descriptions. In addition, the embodiments of the present invention referred to in the following description are typically only some, but not all, embodiments of the present invention. Therefore, all other embodiments, which can be made by one of ordinary skill in the art without undue burden, are intended to be within the scope of the present invention, based on the embodiments of the present invention.
The raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art unless specifically stated otherwise; the methods used in the examples of the present invention are those known to those skilled in the art unless specifically stated otherwise.
If no special description exists, the waste materials selected in the embodiment of the invention are all purchased from Nd with high temperature failure obtained by market recovery 2 Fe 14 The B neodymium-iron-boron magnet mainly comprises a heat engine, a car engine and the like, the working temperature is about 180-220 ℃, the components are basically Nd 12+/-2 at%, B4.5+/-0.5 at% and the balance Fe and unavoidable impurities through characterization; the original calibration remanence of the waste is not less than 1.17 and T at 25 ℃, the remanence (Br) of the waste after failure is not less than 0.9 and T, the intrinsic coercivity (Hcj) is not less than 10 KOe, and the magnetic energy product (BH) max ）≥28 MGSOe。
The neodymium-iron-boron magnet obtained in the embodiment of the invention has the dimensions of 40 mm multiplied by 40 mm multiplied by 30 mm unless otherwise specified.
Example 1
A preparation process of a neodymium iron boron magnet based on waste recycling comprises the following steps:
1) Ultrasonic cleaning the waste for 30 min, washing with clear water, oven drying, crushing the waste to 100 mesh, and collecting 100 mesh Ce-Cu alloy powder (from KETAI, the same applies below) and 220 mesh ZrO 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder;
the mixed powder comprises 10 percent wt percent of Ce-Cu alloy and ZrO 2 13 wt%, the balance being waste powder;
2) And (3) placing the mixed powder in the step (1) in a mould to orient for 25 min at the magnetic field intensity of 1.35T, compacting for 20 min at the pressure of 220 Mpa, sintering for 5 h at the temperature of 980 ℃ in a vacuum atmosphere, preserving the heat for 2 h at the temperature of 800 ℃, then carrying out rapid oil quenching for 30 min at the temperature of 80 ℃, tempering for 10 h at the temperature of 460 ℃, and naturally cooling to obtain the NdFeB magnet.
The performance of the neodymium-iron-boron magnet obtained in example 1 was subjected to characterization test, and the results are shown in the following table.
| Test temperature | Br(T) | Hcj(KOe) | BH max （MGSOe） |
| 25 ℃ | 1.16 | 14.21 | 40.34 |
| 75 ℃ | 1.16 | 13.09 | 39.03 |
| 125 ℃ | 1.15 | 11.73 | 37.88 |
| 180 ℃ | 1.13 | 9.40 | 36.33 |
| 220 ℃ | 1.11 | 4.43 | 34.89 |
As can be seen from the characterization results, the neodymium iron boron magnet obtained by the invention has good magnetic performance and better high temperature resistance, and the magnet with the same standard before the failure of the waste is purchased, the characterization result of the residual magnetic performance of the magnet under the test temperature condition of 180 ℃ is 1.11T, and the residual magnetic performance of the magnet under the test temperature condition of 220 ℃ is only 1.07T, but the high temperature resistance is lower than that of the recycled magnet of the invention, but the residual magnetic performance of the magnet under the condition of room temperature (25 ℃) is 1.19T and higher than that of the magnet of the invention. The method can effectively regenerate the magnet waste, and can not completely recover the original magnetic property of the magnet waste, but is quite close to the original magnetic property, and the regenerated magnet shows better heat resistance and can be used in a high-temperature working environment.
Example 2
A preparation process of a neodymium iron boron magnet based on waste recycling comprises the following steps:
1) Ultrasonic cleaning the waste for 30 min, washing with clear water, oven drying, crushing the waste to 100 mesh, and collecting 150 mesh Ce-Cu and 220 mesh ZrO 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder;
the components of the mixed powder are Ce-Cu10 wt percent and ZrO 2 13 wt%, the balance being waste powder;
2) Placing the mixed powder in the step 1) in a die to orient for 25 min at a magnetic field strength of 1.35T, compacting for 20 min at a pressure of 220 Mpa, sintering for 5 h at a temperature of 980 ℃ in a vacuum atmosphere, preserving heat for 2 h at 800 ℃, then carrying out rapid oil quenching for 30 min at 80 ℃, tempering for 10 h at a temperature of 460 ℃, and naturally cooling to obtain the NdFeB magnet.
The performance of the neodymium-iron-boron magnet obtained in example 2 was subjected to the same characterization test as in example 1, and the results are shown in the following table.
| Test temperature | Br(T) | Hcj(KOe) | BH max （MGSOe） |
| 25 ℃ | 1.17 | 14.37 | 42.54 |
| 75 ℃ | 1.16 | 13.12 | 41.33 |
| 125 ℃ | 1.15 | 11.81 | 40.04 |
| 180 ℃ | 1.12 | 9.54 | 38.17 |
| 220 ℃ | 1.10 | 4.48 | 36.39 |
From the characterization result, the number of the rare earth copper powder is increased in the embodiment, namely the rare earth copper powder in the embodiment 2 is finer, the surface of the obtained neodymium-iron-boron magnet is free from cracking and cracking, the volume is free from obvious change, and the remanence and magnetic energy product of the neodymium-iron-boron magnet are improved compared with those of the embodiment 1, so that the effect of mixing is affected due to the fact that the number of the rare earth copper powder is too small, the components are easy to segregate, and the performance of the sintered magnet is affected.
Example 3
A preparation process of a neodymium iron boron magnet based on waste recycling comprises the following steps:
1) Ultrasonic cleaning the waste for 30 min, washing with clear water, oven drying, crushing the waste to 100 mesh, and collecting 200 mesh Ce-Cu and 220 mesh ZrO 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder;
the components of the mixed powder are Ce-Cu10 wt percent and ZrO 2 13 wt%, the balance being waste powder;
2) Placing the mixed powder in the step 1) in a die to orient for 25 min at a magnetic field strength of 1.35T, compacting for 20 min at a pressure of 220 Mpa, sintering for 5 h at a temperature of 980 ℃ in a vacuum atmosphere, preserving heat for 2 h at 800 ℃, then carrying out rapid oil quenching for 30 min at 80 ℃, tempering for 10 h at a temperature of 460 ℃, and naturally cooling to obtain the NdFeB magnet.
The performance of the neodymium-iron-boron magnet obtained in example 3 was subjected to the same characterization test as in example 1, and the results are shown in the following table.
| Test temperature | Br(T) | Hcj(KOe) | BH max （MGSOe） |
| 25 ℃ | 1.16 | 14.39 | 40.45 |
| 75 ℃ | 1.16 | 13.16 | 39.13 |
| 125 ℃ | 1.14 | 11.84 | 37.96 |
| 180 ℃ | 1.12 | 9.55 | 36.41 |
| 220 ℃ | 1.10 | 4.48 | 34.90 |
From the characterization results, the mesh number of the rare earth copper powder is further increased in the embodiment compared with the embodiment 2, the surface of the obtained neodymium-iron-boron magnet is damaged, the magnetic energy product is reduced, and the residual magnetic performance is still better.
Comparative example 1
A preparation process of a neodymium iron boron magnet based on waste recycling comprises the following steps:
1) Ultrasonic cleaning the waste for 30 min, washing with clear water, oven drying, crushing the waste to 100 mesh, and collecting 150 mesh Ce and 220 mesh ZrO 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder;
the mixed powder comprises Ce 10 wt percent,ZrO 2 13 wt%, the balance being waste powder;
2) And (3) placing the mixed powder in the step (1) in a mould to orient for 25 min at the magnetic field intensity of 1.35T, compacting for 20 min at the pressure of 220 Mpa, sintering for 5 h at the temperature of 980 ℃ in a vacuum atmosphere, preserving the heat for 2 h at the temperature of 800 ℃, then carrying out rapid oil quenching for 30 min at the temperature of 80 ℃, tempering for 10 h at the temperature of 460 ℃, and naturally cooling to obtain the NdFeB magnet.
The performance of the neodymium-iron-boron magnet obtained in comparative example 1 was subjected to the same characterization test as in example 1, and the results are shown in the following table.
| Test temperature | Br(T) | Hcj(KOe) | BH max （MGSOe） |
| 25 ℃ | 1.15 | 13.55 | 41.43 |
| 75 ℃ | 1.15 | 13.01 | 40.03 |
| 125 ℃ | 1.13 | 11.83 | 38.59 |
| 180 ℃ | 1.10 | 7.29 | 35.02 |
| 220 ℃ | 1.06 | 3.44 | 31.80 |
According to the test result, the comparative example changes rare earth powder to reduce Br, hcj and magnetic energy products of the obtained neodymium-iron-boron magnet, which shows that Cu in the rare earth copper powder can promote rare earth elements to enter into crystal lattices to form solid solutions, the chemical stability is high, the electrode potential is 2.8V higher than Nd, partial low-potential Nd is replaced, a high-potential new crystal boundary phase is formed in the system, the potential difference between the rare earth copper powder and a tetragonal crystal system magnet is reduced, the corrosion resistance of the neodymium-iron-boron magnet is enhanced, the inter-crystal grain magnetic coupling in the neodymium-iron-boron magnet obtained by using the rare earth powder is improved, the grains in the anti-magnetic domain form grow and expand, the surface domain wall of the magnet is displaced, the stability of the magnet is poor, the magnetic performance is reduced, and the heat resistance is also weakened.
Comparative example 2
A preparation process of a neodymium iron boron magnet based on waste recycling comprises the following steps:
1) Ultrasonically cleaning the waste for 30 min, washing with clear water, drying, crushing the waste to 100 meshes, crushing the Ce-Cu powder of 150 meshes with the waste powder hydrogen, and carrying out air flow grinding to obtain mixed powder;
the mixed powder comprises Ce-Cu10 wt percent and the balance of waste powder;
2) And (3) placing the mixed powder in the step (1) in a mould to orient for 25 min at the magnetic field intensity of 1.35T, compacting for 20 min at the pressure of 220 Mpa, sintering for 5 h at the temperature of 980 ℃ in a vacuum atmosphere, preserving the heat for 2 h at the temperature of 800 ℃, then carrying out rapid oil quenching for 30 min at the temperature of 80 ℃, tempering for 10 h at the temperature of 460 ℃, and naturally cooling to obtain the NdFeB magnet.
The performance of the neodymium-iron-boron magnet obtained in comparative example 2 was subjected to the same characterization test as in example 1, and the results are shown in the following table.
| Test temperature | Br(T) | Hcj(KOe) | BH max （MGSOe） |
| 25 ℃ | 1.13 | 14.35 | 40.88 |
| 75 ℃ | 1.13 | 13.10 | 38.73 |
| 125 ℃ | 1.12 | 11.78 | 37.55 |
| 180 ℃ | 1.11 | 9.51 | 35.69 |
| 220 ℃ | 1.09 | 4.42 | 31.95 |
According to the above test results, no ZrO was added in this comparative example 2 The resulting NdFeB magnet had reduced magnetic properties, indicating ZrO 2 Can break the mechanical stability of grain boundary, break larger crystal into more dispersed crystal grains, make the waste particles distributed more uniformly and continuously, make the powder be effectively oriented, and does not add ZrO 2 Segregation occurs in the internal components of the NdFeB magnet obtained by the jet mill, and finally the magnetic energy product is greatly reduced.
Comparative example 3
A preparation process of a neodymium iron boron magnet based on waste recycling comprises the following steps:
1) Ultrasonic cleaning the waste for 30 min, washing with clear water, oven drying, crushing the waste to 100 mesh, and collecting 150 mesh Ce-Cu and 220 mesh ZrO 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder;
the components of the mixed powder are Ce-Cu10 wt percent and ZrO 2 13 wt%, the balance being waste powder;
2) Placing the mixed powder in the step 1) in a die to orient for 25 min at a magnetic field strength of 1.35T, compacting for 20 min at a pressure of 220 Mpa, sintering for 5 h at a temperature of 980 ℃ in a vacuum atmosphere, preserving heat for 2 h at 800 ℃, then carrying out rapid oil quenching for 30 min at 80 ℃, tempering for 10 h at a temperature of 390 ℃, and naturally cooling to obtain the NdFeB magnet.
The performance of the neodymium-iron-boron magnet obtained in comparative example 3 was subjected to the same characterization test as in example 1, and the results are shown in the following table.
| Test temperature | Br(T) | Hcj(KOe) | BH max （MGSOe） |
| 25 ℃ | 1.16 | 13.08 | 39.15 |
| 75 ℃ | 1.15 | 12.02 | 38.23 |
| 125 ℃ | 1.13 | 10.87 | 36.19 |
| 180 ℃ | 1.11 | 8.65 | 35.04 |
| 220 ℃ | 1.08 | 4.30 | 33.66 |
According to the test results, the tempering temperature is reduced in this comparative example, the magnetic performance of the obtained neodymium-iron-boron magnet is reduced, the temperature is lower than the minimum eutectic point temperature of the magnet, the inside grains of the neodymium-iron-boron magnet after tempering at 390 ℃ are fewer, the massive Nd-rich phase is obviously more than that of the neodymium-iron-boron magnet obtained in example 2, the massive Nd-rich phase serving as a source for forming a thin-layer grain boundary phase tends to agglomerate, the availability of the Nd-rich phase is influenced by the existence of the massive Nd-rich phase, reverse magnetization domain nuclei are formed among the neodymium-iron-boron grains, reverse magnetic domain propagation is carried out, the stability of the magnet is reduced, and the intrinsic coercivity of the magnet is reduced. In addition, the concentrated and agglomerated Nd has stronger diffusion trend in a high-temperature working environment and also has the problem of weakening the heat resistance.
Comparative example 4
A preparation process of a neodymium iron boron magnet based on waste recycling comprises the following steps:
1) Ultrasonic cleaning the waste for 30 min, washing with clear water, oven drying, crushing the waste to 100 mesh, and collecting 150 mesh Ce-Cu and 220 mesh ZrO 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder;
the mixed powder comprises 10 wt% of Ce-Cu and 10 wt% of ZrO 2 13 wt%, the balance being waste powder;
2) Placing the mixed powder in the step 1) in a die to orient for 25 min at a magnetic field strength of 1.35T, compacting for 20 min at a pressure of 220 Mpa, sintering for 5 h at a temperature of 980 ℃ in a vacuum atmosphere, preserving heat for 2 h at 800 ℃, performing water quenching for 0.5 h at 80 ℃, and tempering for 10 h at a temperature of 500 ℃ to obtain the NdFeB magnet.
The performance of the neodymium-iron-boron magnet obtained in comparative example 4 was subjected to the same characterization test as in example 1, and the results are shown in the following table.
| Test temperature | Br(T) | Hcj(KOe) | BH max （MGSOe） |
| 25 ℃ | 1.12 | 11.25 | 36.51 |
| 75 ℃ | 1.12 | 10.13 | 35.37 |
| 125 ℃ | 1.10 | 9.44 | 33.90 |
| 180 ℃ | 1.08 | 6.63 | 32.40 |
| 220 ℃ | 1.05 | 3.32 | 30.11 |
According to the test result, the neodymium-iron-boron magnet obtained by changing the quenching mode has reduced magnetic performance, the surface is cracked, along with the increase and extension of gaps, the stray field in the magnet is increased, gaps which are not filled by Nd-rich phases appear in the crystal boundary, magnetic poles perpendicular to the c axis appear in the microscopic regions, and the reverse microscopic demagnetizing field exists in the regions, so that the magnetic performance is reduced.
Comparative example 5
A preparation process of a neodymium iron boron magnet based on waste recycling comprises the following steps:
1) The waste material is cleaned by ultrasonic for 30 min,washing with clear water, oven drying, crushing to 100 mesh, collecting 150 mesh Ce-Cu and 220 mesh ZrO 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder;
the components of the mixed powder are Ce-Cu10 wt percent and ZrO 2 13 wt%, the balance being waste powder;
2) And (3) placing the mixed powder in the step (1) in a mould to orient for 25 min at the magnetic field intensity of 1.35T, compacting for 20 min at the pressure of 220 Mpa, sintering for 5 h at the temperature of 980 ℃ in a vacuum atmosphere, performing rapid oil quenching for 30 min at 80 ℃, tempering for 10 h at the temperature of 460 ℃, and naturally cooling to obtain the neodymium-iron-boron magnet.
The performance of the neodymium-iron-boron magnet obtained in comparative example 5 was subjected to the same characterization test as in example 1, and the results are shown in the following table.
| Test temperature | Br(T) | Hcj(KOe) | BH max （MGSOe） |
| 25 ℃ | 1.12 | 11.52 | 35.16 |
| 75 ℃ | 1.12 | 10.31 | 33.25 |
| 125 ℃ | 1.10 | 9.24 | 31.40 |
| 180 ℃ | 1.08 | 6.06 | 30.01 |
| 220 ℃ | 1.05 | 3.03 | 28.67 |
From the characterization result, the conditions of reduced magnetic performance and surface cracking of the neodymium-iron-boron magnet obtained without heat preservation after sintering are also shown, and the fact that the magnet is not homogenized, the magnetic performance is poor, the loss of the magnet is high Wen Citong, and the intrinsic coercivity is greatly reduced and the magnet is cracked due to the fact that the temperature gradient of each part of the magnet is large.
Comparative example 6
A preparation process of a neodymium iron boron magnet based on waste recycling comprises the following steps:
1) The NdFeB magnet which is the same as the standard in example 1 but is not completely removed after failure is taken as 'waste', but the aging is obvious, the residual magnetic property (25 ℃) is reduced to 1.02 and T, the waste is ultrasonically cleaned for 30 min, then is washed by clean water, is crushed to 100 meshes after being dried, and then is taken out of Ce-Cu of 150 meshes and ZrO of 220 meshes 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder;
the components of the mixed powder are Ce-Cu10 wt percent and ZrO 2 13 wt%, the balance being waste powder;
2) Placing the mixed powder in the step 1) in a die to orient for 25 min at a magnetic field strength of 1.35T, compacting for 20 min at a pressure of 220 Mpa, sintering for 5 h at a temperature of 980 ℃ in a vacuum atmosphere, preserving heat for 2 h at 800 ℃, then carrying out rapid oil quenching for 30 min at 80 ℃, tempering for 10 h at a temperature of 460 ℃, and naturally cooling to obtain the NdFeB magnet.
The performance of the neodymium-iron-boron magnet obtained in comparative example 6 was subjected to the same characterization test as in example 1, and the results are shown in the following table.
| Test temperature | Br(T) | Hcj(KOe) | BH max （MGSOe） |
| 25 ℃ | 1.14 | 13.17 | 41.06 |
| 75 ℃ | 1.13 | 12.19 | 40.11 |
| 125 ℃ | 1.12 | 10.32 | 39.26 |
| 180 ℃ | 1.10 | 9.07 | 36.91 |
| 220 ℃ | 1.07 | 4.52 | 35.30 |
From the characterization results, the selection of the waste materials can also obviously influence the magnetic performance of the neodymium-iron-boron magnet prepared by the process, mainly because the waste materials used in the example have obvious aging and obviously reduced residual magnetic performance, but the waste materials required by the invention are R-phase fully transferred and even decomposed, so that Nd generates a large amount of disordered diffusion and locally enriched magnets in an agglomeration form, and the internal structure of the magnets can be effectively rearranged by virtue of 'attack' of rare earth alloy and zirconia, so that the secondary orientation is facilitated. The aging process of the magnet is still in progress, and no very remarkable Nd enrichment and the like occur, so that the rare earth alloy and the zirconia have poor action and effect, and even negative influence is possible.
Comparative example 7
A preparation process of a neodymium iron boron magnet based on waste recycling comprises the following steps:
1) Neodymium iron boron magnet with relatively low quality of certain brand (detection of Br=1.13T at 25 ℃ C., brand R) 2 Fe 14 B 1.5 ) Performing laboratory aging, heat treating at 180deg.C to reduce magnetic property loss to less than or equal to 0.9T (Br=0.88T detected at 25deg.C), ultrasonic cleaning for 30 min, washing with clear water, oven drying, crushing to 100 mesh, and collecting 150 mesh Ce-Cu and 220 mesh ZrO 2 Crushing the waste powder with hydrogen and carrying out air flow grinding to obtain mixed powder;
the components of the mixed powder are Ce-Cu10 wt percent and ZrO 2 13 wt%, the balance being waste powder;
2) And (3) placing the mixed powder in the step (1) in a mould to orient for 25 min at the magnetic field intensity of 1.35T, compacting for 20 min at the pressure of 220 Mpa, sintering for 5 h at the temperature of 980 ℃ in a vacuum atmosphere, preserving the heat for 2 h at the temperature of 800 ℃, then carrying out rapid oil quenching for 30 min at the temperature of 80 ℃, tempering for 10 h at the temperature of 460 ℃, and naturally cooling to obtain the NdFeB magnet.
The performance of the neodymium-iron-boron magnet obtained in comparative example 7 was subjected to the same characterization test as in example 1, and the results are shown in the following table.
| Test temperature | Br(T) | Hcj(KOe) | BH max （MGSOe） |
| 25 ℃ | 1.10 | 12.36 | 39.98 |
| 75 ℃ | 1.08 | 11.02 | 39.02 |
| 125 ℃ | 1.06 | 9.85 | 38.13 |
| 180 ℃ | 1.03 | 8.31 | 36.15 |
| 220 ℃ | 0.98 | 4.06 | 34.87 |
From the characterization result, for the magnet with more B phase and weaker original magnetic performance, the method can realize the regeneration and recovery of the magnet with the magnetic performance again, but the high temperature resistance of the magnet is obviously weakened, and the magnetic performance of the obtained permanent magnet cannot be effectively improved. Thus, as can be seen from comparison of comparative examples 6 and 7 with examples, the technical scheme of the present invention can be practically universally applied to conventional Nd 2 Fe 14 And B, regenerating and repairing the magnet, and preparing a new high-temperature-resistant magnet by taking the magnet as waste, wherein the magnetic performance of the magnet is weakened, but the heat resistance can be obviously improved. It should be noted, however, that the waste materials to which the method of the present invention is applicable should be those waste materials that are thermally ineffective and meet certain criteria, since the diffusion and enrichment of the components generated during thermal failure is advantageous for the solution of the present invention.
Claims (7)
1. A preparation process of a neodymium-iron-boron magnet based on waste recycling is characterized in that,
the preparation process comprises the following steps:
1) Pretreating the waste, and then taking rare earth copper powder and ZrO 2 Crushing the waste material after pretreatment with hydrogen and carrying out air flow grinding to obtain mixed powder;
2) Placing the mixed powder in the step (1) in a mould for orientation, profiling, sintering, tempering and cooling to obtain a neodymium-iron-boron magnet;
the waste material in the step 1) is neodymium-iron-boron magnet waste material with high-temperature failure, the remanence before failure of the neodymium-iron-boron magnet is more than or equal to 1.16T, and the remanence after failure is less than or equal to 0.90T;
the content of rare earth copper powder in the mixed powder in the step 1) is 5 to 10 percent wt percent, and the content of ZrO 2 The content is 10-15 wt percent, and the balance is waste powder;
the sintering in the step 2) is carried out in a non-nitrogen protective atmosphere or a vacuum atmosphere, 4 to 6 h are sintered at the temperature of 900 to 1050 ℃, and then the temperature is kept at the temperature of 700 to 900 ℃ for 1 to 3 h.
2. The process for preparing the neodymium-iron-boron magnet based on waste recycling according to claim 1, wherein the process comprises the following steps of,
the pretreatment step in the step 1) comprises cleaning and drying, and crushing the waste materials to 60-200 meshes after drying.
3. The process for preparing a NdFeB magnet based on waste recycling according to claim 1 or 2, wherein,
the mesh number of the rare earth copper powder in the step 1) is 100-200 meshes, and the components are La-Cu and/or Ce-Cu and/or Pr-Cu and/or Gd-Cu and/or Ho-Cu and/or Tb-Cu and/or Dy-Cu.
4. The process for preparing a NdFeB magnet based on waste recycling according to claim 1 or 2, wherein,
step 1) the ZrO 2 The mesh number is 200-400 mesh.
5. The process for preparing the neodymium-iron-boron magnet based on waste recycling according to claim 1, wherein the process comprises the following steps of,
the strength of the orientation magnetic field in the step 2) is 1.2-1.35T, and the orientation time is 25-30 min.
6. The process for preparing the neodymium-iron-boron magnet based on waste recycling according to claim 1, wherein the process comprises the following steps of,
and 2) pressing the compression mould at the pressure of 200-240 Mpa.
7. The process for preparing the neodymium-iron-boron magnet based on waste recycling according to claim 1, wherein the process comprises the following steps of,
and 2) oil quenching is carried out before tempering by 0.5-1 h, and tempering is carried out by 8-12 h at the temperature of 400-480 ℃.
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