WO2018192346A1 - 一种稀土永磁材料的制备方法 - Google Patents

一种稀土永磁材料的制备方法 Download PDF

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WO2018192346A1
WO2018192346A1 PCT/CN2018/080650 CN2018080650W WO2018192346A1 WO 2018192346 A1 WO2018192346 A1 WO 2018192346A1 CN 2018080650 W CN2018080650 W CN 2018080650W WO 2018192346 A1 WO2018192346 A1 WO 2018192346A1
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rare earth
magnet
permanent magnet
earth permanent
powder
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PCT/CN2018/080650
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English (en)
French (fr)
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周磊
程星华
刘涛
喻晓军
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安泰科技股份有限公司
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Priority to EP18787125.6A priority Critical patent/EP3614403B1/en
Priority to SI201830550T priority patent/SI3614403T1/sl
Priority to KR1020197030679A priority patent/KR102240453B1/ko
Priority to ES18787125T priority patent/ES2905618T3/es
Priority to US16/605,008 priority patent/US20200161047A1/en
Publication of WO2018192346A1 publication Critical patent/WO2018192346A1/zh

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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
    • H01F41/0293—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
    • 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
    • H01F1/0572—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 with a protective layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
    • C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
    • C23C10/30—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes using a layer of powder or paste on the surface
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C24/00—Coating starting from inorganic powder
    • C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/02—Pretreatment of the material to be coated
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/80—After-treatment
    • 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
    • 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
    • H01F41/0206—Manufacturing of magnetic cores by mechanical means
    • H01F41/0246—Manufacturing of magnetic circuits by moulding or by pressing powder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • B22F2003/247—Removing material: carving, cleaning, grinding, hobbing, honing, lapping, polishing, milling, shaving, skiving, turning the surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • B22F2003/248—Thermal after-treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2301/00—Metallic composition of the powder or its coating
    • B22F2301/35—Iron
    • B22F2301/355—Rare Earth - Fe intermetallic alloys

Definitions

  • the invention relates to a preparation method of a rare earth permanent magnet material, in particular to a method for electrostatically attaching one or more heavy rare earth-rich compounds and pure metal powder on a surface of a sintered NdFeB magnet and high temperature treatment, and low temperature aging improvement magnet.
  • the method of performance belongs to the technical field of rare earth permanent magnet materials.
  • NdFeB permanent magnet materials are widely used in hybrid electric vehicles, wind power generation, energy-saving motors and inverter air conditioners. These fields require magnets to work at high temperatures for a long time, and rare earth permanent magnets should have higher coercivity Hcj.
  • An effective method for improving the coercive force Hcj of NdFeB sintered magnets is to replace Nd in the main phase of the magnet Nd 2 Fe 14 B by heavy rare earth elements such as Dy and Tb to form (Nd, Dy) 2 Fe 14 B, (Nd, Dy) 2 Fe 14 B is more anisotropic than Nd 2 Fe 14 B; thus, the Hcj of the magnet is significantly improved; but these heavy rare earth elements are scarce and expensive, on the other hand, Nd
  • the magnetic moments of iron and iron are arranged in parallel, and Dy and iron are arranged in anti-parallel, so that the remanence Br and the maximum magnetic energy product (BH)max of the magnet are reduced.
  • the present invention aims to provide a method for preparing a rare earth permanent magnet material by electrostatically attaching one or more compounds rich in heavy rare earth elements and other pure metal powders on the surface of a NdFeB substrate.
  • High-temperature sintering to prepare rare earth permanent magnet materials the method not only realizes the orderly arrangement of rare earth elements on the surface and inside of the NdFeB matrix, but also improves the coercive force of the magnet, and the residual magnetism is not significantly reduced.
  • a method for preparing a rare earth permanent magnet material comprising the following steps:
  • Step one weigh the three raw material powders of H, M, and Q according to the atomic percentage content in the general formula H 100-xy M x Q y , and sequentially mix the three raw materials in a nitrogen or other anaerobic environment.
  • H is one or more of fluorides or oxide powders of Dy, Tb, DyTb, Ho, Gd, and M is Nd or/and Pr metal powder
  • Q is one or more of Cu, Al, Zn, Ga, and Sn metal powders
  • Step two the sintered NdFeB magnet is machined into a prescribed shape and size, followed by surface cleaning and drying, thereby obtaining a NdFeB magnet to be processed;
  • Step 3 in an oxygen-free environment, the composite powder is electrostatically attached to the surface of the NdFeB magnet to be treated to obtain a NdFeB magnet with a surface-attached composite powder film;
  • Step 4 the surface-attached composite powder film NdFeB magnet is subjected to vacuum heat treatment, and then cooled with the furnace to obtain a diffused NdFeB magnet;
  • step five the diffused NdFeB magnet is subjected to tempering treatment (immediate treatment) to obtain the rare earth permanent magnet material.
  • the technical principle of the invention is to improve the performance of the magnet by means of electrostatic adhesion and grain boundary diffusion treatment and subsequent tempering treatment; wherein, by electrostatic adhesion, a strong binding force can be formed on the surface of the sintered NdFeB magnet, which is rich in a powder film formed of a compound of a heavy rare earth element and a pure metal powder; a compound rich in heavy rare earth element and a pure metal powder are attached to the surface of the magnet by electrostatic action, and grain boundary diffusion is achieved by subsequent heat treatment, thereby increasing the coercive force of the magnet characteristic.
  • the role of the H component is mainly to provide a heavy rare earth element for subsequent processing, and to improve the magnetic properties of the magnet by element substitution.
  • the main role of the M component is twofold: on the one hand, the heavy rare earth in the heavy rare earth compound powder is reduced at a high temperature to form a simple rare earth metal element; on the other hand, the number of intergranular phases in the grain boundary diffusion process of the magnet is increased, Helps increase efficiency.
  • the M content is 0, the replacement and substitution of the heavy rare earth will require a more complicated form, for example, the addition of a reducing agent and the reducing agent cannot affect the performance of the magnet, or the ruthenium-rich phase in the magnet reacts with the heavy rare earth.
  • the atomic percentage of M is greater than 20, it will cause waste and also reduce the diffusion effect.
  • M is Nd, Pr or PrNd (ie, a mixed powder of two metals of Pr and Nd, and the mass ratio is preferably 1:2-1:5, such as 1:2, 1:2.5, 1:3, 1:4, 1 : 4.5, 1:5) Metal powder.
  • the fluidity and wettability of the liquid phase are important, which is significant for the diffusion results and efficiency.
  • the main role of the Q component is to increase the fluidity and wettability of the heavy rare earth element after replacement, and to enhance the diffusion efficiency; when the atomic percentage of Q is greater than 40, the concentration of the heavy rare earth element in the flowing liquid phase is diluted.
  • the improvement in the performance of the magnet and the diffusion effect are disadvantageous.
  • M is a PrNd metal powder (ie, a mixed powder of two metals of Pr and Nd), and the mass ratio of Pr to Nd is 1:2-1:5. (eg 1:2, 1:2.5, 1:3, 1:4, 1:4.5, 1:5).
  • the raw material powder has a particle size of -150 mesh, and the sieving treatment is a 150 mesh sieve. Because the particle size of the powder is small, less than 150 mesh, there is a possibility of a small agglomeration during mixing, so it needs to be sieved after mixing; the mixing process can be a conventional process in the field, such as the current common mixing equipment. , 360 ° rotary mixing powder.
  • the orientation direction thickness of the NdFeB magnet to be processed is 1-8 mm (for example, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm). If the thickness is too thin, the magnet tends to be bent and deformed in the subsequent treatment, and if the thickness is too thick, the effect of the grain boundary diffusion cannot reach the core of the magnet, resulting in a large difference in internal and external properties.
  • the surface cleaning process is as follows: first, the sintered NdFeB magnet is placed in a degreasing tank for 8-15 minutes (for example, 10 min, 12 min, 14 min). To remove the oil stain on the surface of the magnet; then, through the first water washing, pickling, the second water washing, and the ultrasonic treatment, and finally air drying the surface of the sintered NdFeB magnet.
  • the pickling is pickled with dilute HNO 3 (mass fraction concentration of 50-70%) for a period of 20-45 s (such as 22 s, 28 s, 35 s, 39 s, 44 s), and the ultrasonic treatment time is 20 -45s (such as 22s, 28s, 35s, 39s, 44s), the air drying is fast drying with strong wind.
  • dilute HNO 3 mass fraction concentration of 50-70%
  • the composite powder film has a thickness of 10 to 40 ⁇ m (for example, 12 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 38 ⁇ m). Films with a thickness greater than 40 ⁇ m have poor adhesion, and below 40 ⁇ m, the grain boundary diffusion effect has been optimized, and thickness is not helpful for performance improvement; if it is too thin, the ability to improve performance is limited. More preferably, the composite powder film has a thickness of 25-40 ⁇ m (such as 26 ⁇ m, 28 ⁇ m, 32 ⁇ m, 36 ⁇ m, 39 ⁇ m).
  • electrostatic powder is generally used to adhere the powder containing the curing agent to the surface of the workpiece, and after curing at a low temperature, the surface of the workpiece is protected. If the electrostatic powder does not contain the curing agent for curing, the powder is difficult to adhere to the workpiece for a long time. The surface does not function to protect the workpiece.
  • the raw material powder for improving the performance of the permanent magnetic material of the present invention cannot contain a curing agent (if it contains, it will adversely affect the subsequent high-temperature treatment), and there is no curing process, so the adhesion and film thickness of the composite powder on the surface of the magnet The control is critical and difficult.
  • the inventor sprayed the composite powder onto the surface of the NdFeB magnet to be treated by an electrostatic spray gun by controlling the parameters such as voltage and time to obtain a film of a suitable thickness, and the adhesion was good.
  • the composite powder is sprayed on the surface of the NdFeB magnet to be treated by an electrostatic spray gun, that is, the composite powder is accelerated by a positive or negative electron through a spray gun.
  • Impact on the NdFeB magnet to be treated connected to the cathode or the anode, wherein the process conditions are as follows:
  • the voltage is 30-120kv (such as 35kv, 40kv, 50kv, 60kv, 70kv, 80kv, 90kv, 100kv, 110kv, 115kv), providing the electromotive force between positive and negative ions. If the voltage is too low, the particle impact force is weak and the adhesion is poor. If the voltage is too high, a high corona current will be generated between the workpiece and the nozzle, and the safety is poor; more preferably 50-90 kv;
  • the time is 5-40s (such as 8s, 12s, 16s, 20s, 25s, 30s, 35s, 38s).
  • the time is too short, the deposited powder is less, and the film thickness is thin.
  • the time is too long, the adhesion of the powder reaches a certain level. After the thickness, no more powder is needed (required for subsequent effects), and the adhesion between the powders is also deteriorated; more preferably 15-30 s;
  • the moving speed of the spray gun is 5-45cm/s (such as 6cm/s, 8cm/s, 10cm/s, 15cm/s, 20cm/s, 25cm/s, 30cm/s, 35cm/s, 40cm/s, 42cm/s)
  • the speed is too fast, the powder is unevenly attached, the speed is too slow, and the powder waste is serious; more preferably 10-30 cm/s;
  • the spray distance is 8-35cm (such as 10cm, 12cm, 15cm, 18cm, 22cm, 24cm, 25cm, 28cm); the spray distance is too short and the safety is poor.
  • the spray gun is used to bring out the powder by the airflow, which has an impact on the adhered powder; If the distance is too long, the distance from the powder flying becomes far, the adhesion rate and adhesion are lowered, the efficiency is lowered, and the cost is increased; more preferably 15-25 cm.
  • This application uses an electrostatic spray gun to control the film quality, thickness and cost by controlling the above parameters (voltage, time, spray gun moving speed, jet distance), and finally spray the composite powder onto the surface of the NdFeB magnet to be treated. Appropriate thickness and adhesion of the film layer, while reducing production costs.
  • the conditions of the vacuum heat treatment are as follows: the degree of vacuum is higher than 10 -3 Pa (for example, 5 ⁇ 10 -4 Pa, 1 ⁇ 10 -4 Pa) , 8 ⁇ 10 -5 Pa, 5 ⁇ 10 -5 Pa, 1 ⁇ 10 -6 Pa), the holding temperature is 650-1050 ° C (such as 650 ° C, 700 ° C, 750 ° C, 800 ° C, 850 ° C, 900 ° C, 1000 ° C, 1020 ° C), holding time is 5-50h (6h, 10h, 20h, 30h, 40h, 48h).
  • the holding temperature is 830-870 ° C (such as 835 ° C, 840 ° C, 845 ° C, 850 ° C, 855 ° C, 860 ° C, 865 ° C), the holding time is 30-40 h (such as 32h, 34h, 36h, 38h).
  • the furnace is cooled to not higher than 50 ° C (25 ° C, 30 ° C, 35 ° C, 40 ° C, 45 ° C).
  • 50 °C on the one hand, the magnet is easy to absorb the moisture in the surrounding environment in the hot state, which is unfavorable to the magnetic properties.
  • it is not conducive to heating the components in the furnace body, reducing the service life, and the physical properties after partial oxidation have also occurred. The change caused a change in the temperature distribution in the furnace.
  • the temperature of the tempering treatment is 420-640 ° C (such as 430 ° C, 460 ° C, 500 ° C, 550 ° C, 600 ° C, 630 ° C)
  • the time is 2-10h (such as 3h, 4h, 6h, 8h, 9h).
  • the temperature of the tempering treatment is 420-480 ° C (such as 425 ° C, 430 ° C, 445 ° C, 455 ° C, 470 ° C), and the time is 4-6 h (such as 4.5 h). , 5h, 5.5h).
  • the processing device in the fourth step may be a vacuum heat treatment furnace.
  • a post-processing step is further included: the rare earth permanent magnet material is immersed in dilute nitric acid to remove residual deposits on the surface, and then the deionized water is used.
  • the rare earth permanent magnet material is cleaned; preferably, the dilute nitric acid is a nitric acid alcohol solution, and the mass concentration is 2-10% (3%, 4%, 5%, 6%, 7%, 8%, 9%).
  • the concentration is too high, the window of time matching will be small, the possibility of residue will increase, if the concentration is low, the efficiency will decrease; more preferably, the mass concentration is 4-6%; the soaking time is 60-180s (such as 65s, 70s, 85s, 100s, 120s, 145s, 160s, 170s, 175s).
  • the soaking time is 60-180s (such as 65s, 70s, 85s, 100s, 120s, 145s, 160s, 170s, 175s).
  • the residual deposits on the surface of the magnet are non-magnetic, which may affect the performance of the magnet.
  • the above-mentioned post-treatment to remove the layer material can obtain a magnet with further improved performance, and the soaking time is related to the film thickness.
  • the NdFeB matrix and the heavy rare earth element-rich compound and the pure metal powder are well combined by electrostatic adhesion, and after high temperature treatment, the heavy rare earth compound and the pure metal powder in the powder film are diffused in the magnet to The intersection of the main phase and the rich phase is enriched; the coercivity of the NdFeB magnets treated by these processes is significantly improved, and the effects of evaporation, sputtering, etc. are achieved or exceeded.
  • the preparation method provided by the invention improves the physical properties of the grain boundary phase and the adjacent region by the effective adhesion of the composite powder, the suitable heat treatment temperature, time, effective aging temperature and time, so that the performance of the magnet is significantly improved, and at the same time The use of heavy rare earths is saved.
  • the traditional method is to increase the coercivity by adding heavy rare earths.
  • the remanence is greatly reduced.
  • a large amount of heavy rare earths are present in the main phase particles, so heavy rare earths are needed. More usage.
  • the coercive force of the rare earth permanent magnet material NdFeB magnet prepared by the preparation method provided by the invention can be increased by 4000-14000 Oe, the residual magnetism is only reduced by 1-2%, and the equivalent performance magnet can save 30% of the heavy rare earth use amount.
  • the raw materials required for conventional vapor deposition and sputtering are pure metals, which are more expensive than the fluoride or oxide powder used in the present invention, that is, the raw materials used in the present invention are compounds rich in heavy rare earth elements. (Fluoride or oxide), which is a semi-finished product before metal reduction, is low in price and easy to obtain.
  • the traditional vapor deposition and sputtering processes are a simple physical attachment process, which requires certain temperature and vacuum conditions.
  • the electrostatic adhesion method combines powder and matrix due to different charges of powder and workpiece. The force is stronger, and once the electrostatic adhesion process is over, it can be reused after cleaning.
  • the electrostatic adhesion can be performed at normal temperature, and only nitrogen protection is required. Therefore, the present invention opens up a novel route for improving the performance of the rare earth permanent magnet material NdFeB.
  • the invention is used to improve the performance of the magnet, on the one hand, the high efficiency, the strong rare earth element attachment and the base magnet have strong binding force; on the other hand, the residual powder is convenient to be recycled, the amount of heavy rare earth used is greatly reduced, the cost of the product is lowered, and the product is made. The price/performance ratio is more advantageous.
  • FIG. 1 is a technical flow diagram of a preferred embodiment of the present invention.
  • Example 2 is a structural diagram of a rare earth permanent magnet material prepared in Example 1 of the present invention.
  • FIG. 3 is a diagram showing changes in magnetic properties of magnets before and after processing in the first embodiment of the present invention, in which the abscissa Applied Field, that is, the applied magnetic field strength, and the ordinate, Magnetisation, is the magnetization.
  • the NdFeB magnets to be treated used in the following examples are all sintered NdFeB magnets. In each embodiment, different grades and different batches of commercial sintered NdFeB magnets are used as the magnets to be treated, and the method of the present invention is applicable to various NdFeB magnets. .
  • the equipment used for electrostatic adhesion is electrostatic powder spray line. The manufacturer is Gu'an Keyu Xinpeng Automation Control Equipment Co., Ltd., and the core component electrostatic spray gun adopts German Wagner spray gun.
  • FIG. 1 shows a process flow of a preferred embodiment of the method of the present invention, specifically comprising the steps of: magnet cutting processing, magnet surface cleaning; powder preparation, powder mixing screening; electrostatic adhesion to prepare a magnet attached to a powder film; Diffusion treatment and timeliness; magnet surface processing. Specific embodiments are given below.
  • a composite powder was placed in accordance with a powder ratio formula (TbF 3 ) 95 Nd 2 Al 3 .
  • TbF 3 powder -150 mesh
  • metal Nd powder -150 mesh
  • metal Al powder -150 mesh
  • the commercial 50H grade sintered NdFeB magnet is machined into a shape to be processed, wherein the orientation direction is 1.96 mm thickness; then the cleaning surface procedure is entered, and the surface cleaning procedure is as follows: The magnet is placed in the degreasing tank for 10 min to remove the magnet surface. The oil was washed with water and then pickled with dilute HNO 3 (concentration: 50 wt%) for 20 s, then washed with water and sonicated for 20 s, and then the surface of the magnet was quickly dried by strong wind; thereby obtaining a NdFeB magnet to be treated.
  • the composite powder prepared in the step (1) is subjected to a positron according to a voltage of 70 kV, a time of 30 s, a moving speed of the spray gun of 20 cm/s, and a spray distance of 20 cm; the impact is accelerated to the cathode.
  • the NdFeB magnet to be treated obtained in the step (2) was subjected to a NdFeB magnet having a surface-attached composite powder film having a film thickness of about 40 ⁇ m.
  • the vacuum degree is higher than 10 -3 Pa, and the temperature is maintained at 850 ° C for 35 hours; and the furnace is cooled to not higher than 50 ° C. It was tempered at 490 ° C for 6 hours.
  • the magnet obtained in the step (4) is immersed in dilute nitric acid (concentration: 6 wt%) for 80 s to remove residual deposits on the surface of the magnet; the magnet is cleaned with deionized water to obtain a magnet with improved performance.
  • the coercive force of the rare earth permanent magnet material prepared in this embodiment is improved by 14240 Oe, and the residual magnetism is slightly lowered, which is reduced by 190 Gs.
  • the performance change of the magnet before and after the treatment that is, the NdFeB magnet to be treated obtained in the step (2) and the permanent magnet finally obtained after the treatment in the steps (3), (4), and (5) are subjected to performance test, and the subsequent embodiments are also So) as shown in Table 1.
  • the microstructure of the rare earth permanent magnet material prepared in this embodiment is shown in Fig. 2. It can be seen from the figure that a uniform and continuous grain boundary phase is coated around the main phase particles, which will greatly improve the magnet.
  • the demagnetization coupling ability in the applied magnetic field is beneficial to the improvement of the coercive force of the magnet.
  • 3 is a graph showing changes in performance of magnets before and after treatment in Example 1 of the present invention, from which it can be seen that the technical treatment of steps (3), (4), and (5) of the present embodiment, the correction of sintered NdFeB
  • the tenacity increased from 17740Oe to 31980Oe, an increase of 14240Oe, and a slight decrease in remanence, which was reduced from 13960Gs to 13770G, which was reduced by 190Gs.
  • a composite powder was placed in accordance with a powder ratio formula (DyF 3 ) 95 Nd 1 Al 4 .
  • DyF 3 powder -150 mesh; metal Nd powder, -150 mesh; metal Al powder, -150 mesh; mix the above powder uniformly, and sieve through 150 mesh, powder mixing and sieving process under nitrogen atmosphere .
  • the commercial 48H grade sintered NdFeB magnet is machined into a shape to be processed, wherein the orientation direction is 3 mm thickness; then the cleaning surface procedure is entered, and the surface cleaning procedure is as follows: The magnet is placed in the degreasing tank for 10 min to remove the magnet surface. The oil is stained with water, washed with dilute HNO 3 for 20 s, washed with water and sonicated for 20 s, and then the surface of the magnet is quickly dried by strong wind; thereby obtaining a NdFeB magnet to be treated.
  • the composite powder prepared in the step (1) is subjected to a positron of the spray gun with a voltage of 60 kV, a time of 25 s, a moving speed of the spray gun of 20 cm/s, and a spray distance of 20 cm, and accelerates the impact to the cathode.
  • the NdFeB magnet to be treated obtained in the step (2) was subjected to a NdFeB magnet having a surface-attached composite powder film having a film thickness of about 30 ⁇ m.
  • the NdFeB magnet of the surface-attached composite powder film obtained in the step (3) is placed in a vacuum heat treatment furnace, the degree of vacuum is higher than 10 -3 Pa, and the temperature is maintained at 830 ° C for 30 hours; and the furnace is cooled to not higher than 50 ° C. It was tempered at 510 ° C for 4 hours.
  • the magnet obtained in the step (4) was immersed in dilute nitric acid (concentration: 5.5 wt%) for 60 s to remove residual deposits on the surface of the magnet; the magnet was cleaned with deionized water to obtain a magnet with improved performance.
  • the rare earth permanent magnet material prepared in this example has a coercive force of 7500 Oe, a slight decrease in remanence and a decrease of 175 Gs.
  • the performance changes of the magnets before and after the treatment are shown in Table 1.
  • a composite powder was placed in accordance with a powder ratio formula (TbF 3 ) 95 Cu 5 .
  • TbF 3 powder, -150 mesh; metal Cu powder, -150 mesh was weighed; the above powder was uniformly mixed and sieved through 150 mesh, and the powder mixing and sieving process was carried out under a nitrogen atmosphere.
  • the commercial 42M grade sintered NdFeB magnet is machined into a shape to be processed, wherein the orientation direction is 5 mm thickness; then the cleaning surface program is entered, and the surface cleaning procedure is as follows: the magnet is placed in the degreasing tank for 10 minutes to remove the magnet surface. The oil is stained with water, washed with dilute HNO 3 for 35 s, washed with water and sonicated for 35 s, and then the surface of the magnet is quickly dried by strong wind; thereby obtaining a NdFeB magnet to be treated.
  • the composite powder prepared in the step (1) is subjected to a positron of the spray gun with a voltage of 60 kV, a time of 25 s, a moving speed of the spray gun of 20 cm/s, and a spray distance of 20 cm, and accelerates the impact to the cathode.
  • the NdFeB magnet to be treated obtained in the step (2) was subjected to a NdFeB magnet having a surface-attached composite powder film having a film thickness of about 30 ⁇ m.
  • the NdFeB magnet of the surface-attached composite powder film obtained in the step (3) is placed in a vacuum heat treatment furnace, the degree of vacuum is higher than 10 -3 Pa, and the temperature is maintained at 860 ° C for 35 hours; and the furnace is cooled to not higher than 50 ° C. It was tempered at 500 ° C for 6 hours.
  • the magnet obtained in the step (4) was immersed in dilute nitric acid (concentration: 6.5 wt%) for 100 s to remove residual deposits on the surface of the magnet; the magnet was cleaned with deionized water to obtain a magnet with improved performance.
  • the rare earth permanent magnet material prepared in this embodiment has a coercive force of 12000 Oe, a slight decrease in remanence and a decrease of 180 Gs.
  • the performance changes of the magnets before and after the treatment are shown in Table 1.
  • a composite powder was placed in accordance with a powder ratio formula (HoF 3 ) 97 Pr 1 Cu 2 . Weigh HoF 3 powder, -150 mesh; metal Pr powder, -150 mesh; metal Cu powder, -150 mesh; mix the above powder uniformly, and sieve through 150 mesh, powder mixing and sieving process under nitrogen atmosphere .
  • HoF 3 powder ratio formula
  • the commercial 42M grade sintered NdFeB magnet is machined into a shape to be processed, wherein the orientation direction is 3 mm thickness; then the cleaning surface procedure is entered, and the surface cleaning procedure is as follows: the magnet is placed in the degreasing tank for 10 min to remove the magnet surface. The oil was stained with water, washed with dilute HNO 3 for 25 s, washed with water and sonicated for 25 s, and then the surface of the magnet was quickly dried by strong wind; thereby obtaining a NdFeB magnet to be treated.
  • the composite powder prepared in the step (1) is subjected to a positron according to a voltage of 50 kV, a time of 15 s, a moving speed of the spray gun of 25 cm/s, and a spray distance of 20 cm, and accelerates the impact to the cathode.
  • the NdFeB magnet to be treated obtained in the step (2) was subjected to a NdFeB magnet having a surface-attached composite powder film having a film thickness of about 25 ⁇ m.
  • the vacuum degree is higher than 10 -3 Pa, and the temperature is maintained at 850 ° C for 35 hours; and the furnace is cooled to not higher than 50 ° C. It was tempered at 480 ° C for 4 hours.
  • the magnet obtained in the step (4) was immersed in dilute nitric acid (concentration: 5.5 wt%) for 60 s to remove residual deposits on the surface of the magnet; the magnet was cleaned with deionized water to obtain a magnet with improved performance.
  • the rare earth permanent magnet material prepared in this embodiment has a coercive force of 4000 Oe, a slight decrease in remanence, and a decrease of 210 Gs.
  • the performance changes of the magnets before and after the treatment are shown in Table 1.
  • a composite powder was placed in accordance with a powder ratio formula ((DyTb)F 3 ) 96 Cu 1 Al 3 .
  • the commercial 52SH grade sintered NdFeB magnet is machined into a shape to be processed, wherein the orientation direction is 6 mm thickness; then the cleaning surface procedure is entered, and the surface cleaning procedure is as follows: the magnet is placed in the degreasing tank for 10 min to remove the magnet surface. The oil was stained with water, washed with dilute HNO 3 for 45 s, washed with water and sonicated for 45 s, and then the surface of the magnet was quickly dried by strong wind; thereby obtaining a NdFeB magnet to be treated.
  • Step (3) Under the argon atmosphere, the composite powder prepared in the step (1) is subjected to a positron of the spray gun with a voltage of 65 kV, a time of 28 s, a moving speed of the spray gun of 20 cm/s, and a spray distance of 18 cm, and accelerates the impact to the cathode.
  • the NdFeB magnet of the surface-attached composite powder film obtained in the step (3) is placed in a vacuum heat treatment furnace, the degree of vacuum is higher than 10 -3 Pa, and the temperature is maintained at 870 ° C for 40 hours; and the furnace is cooled to not higher than 50 ° C. It was tempered at 520 ° C for 6 hours.
  • the magnet obtained in the step (4) is immersed in dilute nitric acid (concentration: 6 wt%) for 90 s to remove residual deposits on the surface of the magnet; the magnet is cleaned with deionized water to obtain a magnet with improved performance.
  • the rare earth permanent magnet material prepared in this example has a coercive force of 11000 Oe, a slight decrease in remanence and a decrease of 168 Gs.
  • the performance changes of the magnets before and after the treatment are shown in Table 1.
  • a composite powder was placed in accordance with a powder ratio formula (GdF 3 ) 98 Cu 2 .
  • GdF 3 powder, -150 mesh; metal Cu powder, -150 mesh was weighed; the above powder was uniformly mixed and sieved through 150 mesh, and the powder mixing and sieving process was carried out under a nitrogen atmosphere.
  • the commercial 35M+ grade sintered NdFeB magnet is machined into a shape to be processed, wherein the orientation direction is 3 mm thickness; then the cleaning surface procedure is entered, and the surface cleaning procedure is as follows: the magnet is placed in the degreasing tank for 10 minutes to remove the magnet surface. The oil was stained with water, washed with dilute HNO 3 for 25 s, washed with water and sonicated for 25 s, and then the surface of the magnet was quickly dried by strong wind; thereby obtaining a NdFeB magnet to be treated.
  • Step (3) Under the argon atmosphere, the composite powder prepared in the step (1) is subjected to a positron of the spray gun with a voltage of 65 kV, a time of 25 s, a moving speed of the spray gun of 20 cm/s, and a spray distance of 20 cm, and accelerates the impact to the cathode.
  • the NdFeB magnet of the surface-attached composite powder film obtained in the step (3) is placed in a vacuum heat treatment furnace, the degree of vacuum is higher than 10 -3 Pa, and the temperature is maintained at 840 ° C for 35 hours; and the furnace is cooled to not higher than 50 ° C. It was tempered at 490 ° C for 4 hours.
  • the magnet obtained in the step (4) is immersed in dilute nitric acid (concentration: 5 wt%) for 60 s to remove residual deposits on the surface of the magnet; the magnet is cleaned with deionized water to obtain a magnet with improved performance.
  • the rare earth permanent magnet material prepared in this example has a coercive force of 4200 Oe and a slight decrease in remanence and a decrease of 208 Gs.
  • the performance changes of the magnets before and after the treatment are shown in Table 1.
  • a composite powder was placed in accordance with a powder ratio formula (TbO 3 ) 94 Nd 1 Al 5 .
  • TbO 3 powder -150 mesh
  • metal Nd powder -150 mesh
  • metal Al powder -150 mesh
  • the commercial 48H+ grade sintered NdFeB magnet is machined into a shape to be processed, wherein the orientation direction is 8 mm thickness; then the cleaning surface procedure is entered, and the surface cleaning procedure is as follows: the magnet is placed in the degreasing tank for 10 minutes to remove the magnet surface. The oil was stained with water, washed with dilute HNO 3 for 45 s, washed with water and sonicated for 45 s, and then the surface of the magnet was quickly dried by strong wind; thereby obtaining a NdFeB magnet to be treated.
  • Step (3) In an argon atmosphere, the composite powder prepared in the step (1) is subjected to a positron according to a voltage of 75 kV, a time of 30 s, a moving speed of the spray gun of 20 cm/s, and a spray distance of 20 cm, and the impact is accelerated to the cathode.
  • the NdFeB magnet of the surface-attached composite powder film obtained in the step (3) is placed in a vacuum heat treatment furnace, the degree of vacuum is higher than 10 -3 Pa, and the temperature is maintained at 860 ° C for 40 hours; and the furnace is cooled to not higher than 50 ° C. It was tempered at 490 ° C for 5 hours.
  • the magnet obtained in the step (4) is immersed in dilute nitric acid (concentration: 8 wt%) for 180 s to remove residual deposits on the surface of the magnet; the magnet is cleaned with deionized water to obtain a magnet with improved performance.
  • the rare earth permanent magnet material prepared in this example has a coercive force of 8000 Oe and a slight decrease in remanence and a decrease of 185 Gs.
  • the performance changes of the magnets before and after the treatment are shown in Table 1.
  • a composite powder was placed in accordance with a powder ratio formula (DyO 3 ) 97 (PrNd) 2 Al 1 .
  • DyO 3 powder -150 mesh
  • metal PrNd powder Pr and Nd mass ratio is 1:4
  • -150 mesh metal Al powder, -150 mesh; mix the above powder uniformly and sieve through 150 mesh
  • the powder mixing and sieving process is carried out under a nitrogen atmosphere.
  • the commercial 42M grade sintered NdFeB magnet is machined into a shape to be processed, wherein the orientation direction is 6 mm thickness; then the cleaning surface procedure is entered, and the surface cleaning procedure is as follows: the magnet is placed in the degreasing tank for 10 min to remove the magnet surface. The oil was stained with water, washed with dilute HNO 3 for 45 s, washed with water and sonicated for 45 s, and then the surface of the magnet was quickly dried by strong wind; thereby obtaining a NdFeB magnet to be treated.
  • Step (3) Under the argon atmosphere, the composite powder prepared in the step (1) is subjected to a positron of the spray gun with a voltage of 75 kV, a time of 30 s, a moving speed of the spray gun of 18 cm/s, and a spray distance of 22 cm, and accelerates the impact to the cathode.
  • the NdFeB magnet of the surface-attached composite powder film obtained in the step (3) is placed in a vacuum heat treatment furnace, the degree of vacuum is higher than 10 -3 Pa, and the temperature is maintained at 830 ° C for 40 hours; and the furnace is cooled to not higher than 50 ° C. It was tempered at 490 ° C for 6 hours.
  • the magnet obtained in the step (4) is immersed in dilute nitric acid (concentration: 7 wt%) for 120 s to remove residual deposits on the surface of the magnet; the magnet is cleaned with deionized water to obtain a magnet with improved performance.
  • the rare earth permanent magnet material prepared in this example has a coercive force of 6500 Oe, a slight decrease in remanence and a decrease of 190 Gs.
  • the performance changes of the magnets before and after the treatment are shown in Table 1.
  • a composite powder was placed in accordance with a powder ratio formula (TbF 3 ) 46 (DyO 3 ) 48 Nd 2 ZnSnCu 2 .
  • TbF 3 and DyO 3 powder -150 mesh; metal Nd powder, -150 mesh; metal Zn, Sn, Cu powder, -150 mesh; mix the above powder evenly, sieve through 150 mesh, mix and pass the powder
  • the sieving process is carried out under a nitrogen atmosphere.
  • the commercial 46UH grade sintered NdFeB magnet is machined into a shape to be processed, wherein the orientation direction is 4.5 mm thickness; then the cleaning surface procedure is entered, and the surface cleaning procedure is as follows: the magnet is placed in the degreasing tank for 10 min to remove the magnet surface. The oil stain was washed with water and then washed with dilute HNO 3 for 30 s, then washed with water and sonicated for 30 s, and then the surface of the magnet was quickly dried by strong wind; thereby obtaining a NdFeB magnet to be treated.
  • Step (3) Under the argon atmosphere, the composite powder prepared in the step (1) is subjected to a positron of the spray gun with a voltage of 70 kV, a time of 25 s, a moving speed of the spray gun of 18 cm/s, and a spray distance of 22 cm, and accelerates the impact to the cathode.
  • the NdFeB magnet of the surface-attached composite powder film obtained in the step (3) is placed in a vacuum heat treatment furnace, the degree of vacuum is higher than 10 -3 Pa, and the temperature is maintained at 845 ° C for 30 hours; and the furnace is cooled to not higher than 50 ° C. It was tempered at 490 ° C for 6 hours.
  • the magnet obtained in the step (4) was immersed in dilute nitric acid (concentration: 5.0 wt%) for 80 s to remove residual deposits on the surface of the magnet; the magnet was cleaned with deionized water to obtain a magnet with improved performance.
  • the rare earth permanent magnet material prepared in this example has a coercive force of 8500 Oe and a slight decrease in residual magnetism, which is reduced by 170 Gs.
  • the performance changes of the magnets before and after the treatment are shown in Table 1.
  • Example 10-13 except that the composite powder film thickness is different from that of Example 2, the other process parameters are the same as in Example 2; wherein, in Example 10, the composite powder film thickness is about 12 ⁇ m, and the composite powder film thickness in Example 11 is about The thickness of the composite powder film of Example 12 was about 5 ⁇ m, and the thickness of the composite powder film of Example 13 was about 45 ⁇ m.
  • the performance changes of the magnets before and after treatment are shown in Table 2.
  • Example 14-15 except that the holding temperature and the holding time in the vacuum heat treatment in the step (4) are different from those in the second embodiment, the other process parameters are the same as in the second embodiment; wherein the vacuum heat treatment condition in the embodiment 14 is: 1000 ° C heat preservation. 10h, the vacuum heat treatment conditions in Example 15 were: 700 ° C for 48 h.
  • Table 2 The performance changes of the magnets before and after treatment are shown in Table 2.
  • Example 16-17 except that the tempering treatment temperature and time of the step (4) are different from those of the embodiment 2, the other process parameters are the same as those of the embodiment 2; wherein the tempering treatment condition in the embodiment 16 is: tempering at 430 ° C After treatment for 8 h, the tempering treatment conditions in Example 17 were: tempering treatment at 640 ° C for 2 h.
  • Table 2 The performance changes of the magnets before and after treatment are shown in Table 2.
  • Example 18-23 except that the composition of the composite powder used was different from that of Example 2, the other process parameters were the same as in Example 2; the specific composite powder composition and the change in the properties of the magnet before and after the treatment are shown in Table 3.

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Abstract

一种稀土永磁材料的制备方法：首先按照通式H 100-x-yM xQ y中的原子百分比含量称取H、M、Q三种原料粉末，在氮气或其他无氧环境下进行混合、过筛处理，得到复合粉末；然后，将烧结NdFeB磁体机械加工成规定形状和尺寸，进行表面清理及干燥，得到待处理NdFeB磁体；其次，在无氧的环境下将复合粉末通过静电附着于待处理NdFeB磁体的表面；再依次进行真空热处理、回火处理，从而得到该稀土永磁材料。采用上述方法效率高，重稀土元素附着物和基体磁体结合力强；残余粉料回收方便；制备的NdFeB磁体矫顽力可提高4000～14000Oe，剩磁仅降低1-2％，同等性能磁体可节约重稀土使用量30％。

Description

一种稀土永磁材料的制备方法 技术领域
本发明涉及一种稀土永磁材料的制备方法，特别涉及一种采用静电附着一种或多种富含重稀土的化合物和纯金属粉末在烧结钕铁硼磁体表面并高温处理、低温时效提高磁体性能的方法，属于稀土永磁材料技术领域。
背景技术
钕铁硼永磁材料广泛应用于混合动力汽车、风力发电、节能电机和变频空调等领域中，这些领域要求磁体长时间在高温下工作，稀土永磁体应具有更高的矫顽力Hcj。传统的提高NdFeB烧结磁体矫顽力Hcj的一种有效方法是通过重稀土元素如镝(Dy)、铽(Tb)取代磁体主相Nd 2Fe 14B中的Nd，形成(Nd、Dy) 2Fe 14B，(Nd、Dy) 2Fe 14B的各向异性强于Nd 2Fe 14B；因而，磁体的Hcj得到显著提高；但这些重稀土元素资源稀缺、价格昂贵，另一方面，Nd和铁的磁矩是平行排列，而Dy与铁则是反平行排列，因而，磁体的剩磁Br及最大磁能积(BH)max都会降低。
近些年，许多研究机构报道了多种将稀土元素从磁体表面扩散到基体内部的工艺。这些工艺方法使渗透的稀土元素沿着晶界以及主相晶粒表面区域，使得稀土元素能择优分布，不仅提高了矫顽力，还节约了贵重稀土的使用量，使剩磁及磁能积没有明显降低。目前国内外对利用晶界扩散的原理进行磁体性能提高的研究已进行了十多年。晶界扩散处理技术主要采用涂覆、沉积、镀覆、溅射、粘覆等方式，使金属粉末(如Dy、Tb或其它稀土元素)或化合物附着在磁体外表面，通过热处理使金属粉末或化合物经晶界扩散到烧结磁体主相内，这种晶界扩散技术对烧结NdFeB磁体的成分、微观组织和磁性能都有显著的影响。然而，在这些研究中，仍有一些问题亟待解决：(1)利用溅射将Dy/Tb附着在NdFeB烧结磁铁的表面的方法生产率低，工序费用过高，容易出现融坑等缺陷，蒸镀过程中大量稀土金属散布在加热炉腔室内，造成了重稀土金属的不必要浪费；(2)采 用气相沉淀的方法，存在重稀土元素利用率低，处理温度高等缺点；(3)在表面涂覆稀土氧化物或氟化物加热扩散则存在矫顽力提高受限的问题；(4)另外由于Dy/Tb昂贵，最有效地利用Dy/Tb的资源，也是该类技术中的关键问题。
发明内容
针对现有技术的不足，本发明的目的在于提供一种稀土永磁材料的制备方法，该方法是在NdFeB基体表面静电附着一种或多种富含重稀土元素的化合物和其他纯金属粉末并高温烧结以制备稀土永磁材料，该方法不仅实现了稀土元素在NdFeB基体表面及内部的有序排列，而且提高了磁体的矫顽力，同时剩磁基本没有明显降低。
为了实现上述目的，本发明采用了以下技术方案：
一种稀土永磁材料的制备方法，包括如下操作步骤：
步骤一，按照通式H 100-x-yM xQ y中的原子百分比含量称取H、M、Q三种原料粉末，在氮气或其他无氧环境下将所述三种原料依次进行混合处理和过筛处理，得到复合粉末；所述通式中，H为Dy、Tb、DyTb、Ho、Gd的氟化物或氧化物粉末中的一种或多种，M为Nd或/和Pr金属粉末，Q为Cu、Al、Zn、Ga和Sn金属粉末中的一种或多种，x、y分别为原料M和原料Q的原子百分含量，x＝0-20(比如0、1、3、5、7、9、11、13、15、17、19)、y＝0-40(比如0、1、3、5、7、8、9、11、13、15、17、19、20、23、28、30、34、37、39)且x和y不同时为零；
步骤二，将烧结NdFeB磁体机械加工成规定形状和尺寸，随后进行表面清理及干燥，从而得到待处理NdFeB磁体；
步骤三，在无氧的环境下，将所述复合粉末通过静电附着于所述待处理NdFeB磁体的表面，得到表面附着复合粉末膜的NdFeB磁体；
步骤四，将所述表面附着复合粉末膜的NdFeB磁体进行真空热处理，之后随炉冷却，从而得到扩散后的NdFeB磁体；
步骤五，将所述扩散后的NdFeB磁体进行回火处理(即时效处理)，从而得到所述稀土永磁材料。
本发明的技术原理是：利用静电附着方式和晶界扩散处理及后续回火处理来改善磁体性能；其中，通过静电附着方式可以在烧结NdFeB磁体表 面形成一种结合力较好的、由富含重稀土元素的化合物和纯金属粉末形成的粉末膜；将富含重稀土元素的化合物和纯金属粉末通过静电作用附着在磁体表面，通过随后的热处理实现晶界扩散，从而提高磁体的矫顽力特性。
H成分的作用主要在于为后续处理提供重稀土元素，通过元素取代，来提高磁体磁性能。
M成分的主要作用有两方面：一方面在高温的情况下将重稀土化合物粉末中的重稀土还原出来，形成重稀土金属单质；另一方面增加磁体晶界扩散过程中晶间相的数量，有助于增加效率。当M含量为0时，重稀土的置换和取代将需要更复杂的形式实现，例如，添加还原剂而且还原剂不能对磁体性能有影响，或者磁体内的富钕相和重稀土反应。当M的原子百分比含量大于20时，会造成浪费同时也会降低扩散效果。这里M为Nd、Pr或PrNd(即Pr、Nd两种金属的混合粉，质量比优选为1:2-1:5，比如1:2、1:2.5、1:3、1:4、1:4.5、1:5)金属粉末。
重稀土置换后需要从磁体表层到心部扩散，液相的流动性和浸润性很重要，对扩散结果和效率意义重大。Q成分的主要作用是增加重稀土元素被置换后的流动性和浸润性，增强扩散效率；当Q的原子百分比含量大于40时，会对流动的液相中的重稀土元素造成浓度稀释，对磁体性能的提高和扩散效果反而是不利的。
在上述方法中，作为一种优选实施方式，在所述步骤一中，所述通式中x＝1-15、y＝4-25。
在上述方法中，作为一种优选实施方式，在所述步骤一中，M为PrNd金属粉末(即Pr、Nd两种金属的混合粉)，Pr和Nd质量比为1:2-1:5(比如1:2、1:2.5、1:3、1:4、1:4.5、1:5)。在上述方法中，作为一种优选实施方式，在所述步骤一中，所述原料粉末粒度为-150目，所述过筛处理为过150目筛。因为粉料的粒径较小，小于150目，混合时存在小部分团聚的可能性，因此需要在混合后进行过筛；混粉工艺可以为本领域常规工艺，比如采用目前普通的混粉设备，360°回转混粉。
在上述方法中，作为一种优选实施方式，在所述步骤二中，所述待处理NdFeB磁体的取向方向厚度为1-8mm(比如2mm、3mm、4mm、5mm、6mm、7mm)。该厚度过薄则在后续处理时磁体易发生弯曲变形，过厚则晶界扩散的效果无法达到磁体心部，导致性能的内外差很大。
在上述方法中，作为一种优选实施方式，在所述步骤二中，所述表面清理的过程如下：首先将所述烧结NdFeB磁体放入除油槽中浸泡8-15min(比如10min、12min、14min)以去除磁体表面的油污；然后依次经第一次水洗、酸洗、第二次水洗及超声波处理，最后风干所述烧结NdFeB磁体表面。优选地，所述酸洗采用稀HNO 3(质量分数浓度为50-70％)酸洗、时间为20-45s(比如22s、28s、35s、39s、44s)，所述超声波处理的时间为20-45s(比如22s、28s、35s、39s、44s)，所述风干采用强风快速干燥。
在上述方法中，作为一种优选实施方式，在所述步骤三中，所述复合粉末膜厚度为10-40μm(比如12μm、15μm、20μm、25μm、30μm、35μm、38μm)。大于40μm厚度的膜的附着力差，且40μm以下已经将晶界扩散效果达到了最佳，再厚也不会对性能提高有帮助；过薄的话，提高性能的能力有限。更优选地，所述复合粉末膜厚度为25-40μm(比如26μm、28μm、32μm、36μm、39μm)。
现有技术中一般采用静电把含有固化剂的粉末附着在工件表面，经低温固化后达到防护工件表面的作用，如静电粉末中不含有固化用的固化剂的话，粉末很难长期有效附着于工件表面，起不到保护工件的作用。而本发明用于永磁材料性能改善的原料粉末不能含有固化剂(如果含有，将对后续的高温处理产生不利影响)，也没有固化过程，因此复合粉末在磁体表面的附着力和成膜厚度的控制很关键也很难。发明人通过电压、时间等参数的控制，采用静电喷枪将复合粉末喷射到待处理的钕铁硼磁体表面，得到合适厚度的膜层，而且附着力良好。
上述方法中，作为一种优选实施方式，在所述步骤三中，将所述复合粉末通过静电喷枪喷射于所述待处理NdFeB磁体的表面，即复合粉末通过喷枪带正电或负电子，加速撞击到与阴极或阳极相连的待处理NdFeB磁体上，其中，工艺条件如下：
电压为30-120kv(比如35kv、40kv、50kv、60kv、70kv、80kv、90kv、100kv、110kv、115kv)，提供正负离子间的电动势，电压过低，则粉末的颗粒撞击力弱，附着力差；电压过高，则会在工件和喷嘴间产生较高的电晕电流，安全性差；更优选为50-90kv；
时间为5-40s(比如8s、12s、16s、20s、25s、30s、35s、38s)，时间过短时，附着的粉末少，产生的膜厚薄；时间过长时，由于粉末的附着达 到一定厚度后，不需要更多的粉末(后续效果所需)，粉末间的附着力也变差；更优选为15-30s；
喷枪移动速度5-45cm/s(比如6cm/s、8cm/s、10cm/s、15cm/s、20cm/s、25cm/s、30cm/s、35cm/s、40cm/s、42cm/s)；速度过快，粉末附着不均匀，速度过慢，粉末浪费严重；更优选为10-30cm/s；
喷射距离8-35cm(比如10cm、12cm、15cm、18cm、22cm、24cm、25cm、28cm)；喷射距离过短安全性差，喷枪是靠气流带出粉末的，对已附着的粉末有冲击作用；喷射距离过远，粉末飞射的距离变远，附着率和附着力都会下降，降低了效率，也增加了成本；更优选为15-25cm。本申请采用静电喷枪，通过对上述参数(电压、时间、喷枪移动速度、喷射距离)的控制，影响成膜质量、厚度和成本，最终将复合粉末喷射到待处理的钕铁硼磁体表面，得到合适厚度、附着力良好的膜层，同时降低了生产成本。
在上述方法中，作为一种优选实施方式，在所述步骤四中，所述真空热处理的条件如下：真空度高于10 -3Pa(比如5×10 -4Pa、1×10 -4Pa、8×10 -5Pa、5×10 -5Pa、1×10 -6Pa)，保温温度为650-1050℃(比如650℃、700℃、750℃、800℃、850℃、900℃、1000℃、1020℃)，保温时间为5-50h(6h、10h、20h、30h、40h、48h)。保温温度过低，则处理效果不明显；保温温度过高，将导致晶粒异常长大，反而使磁性能恶化；温度和时间的匹配将有助于既发挥很好的处理效果，也有效利用能源。更优选地，在所述步骤四中，所述保温温度为830-870℃(比如835℃、840℃、845℃、850℃、855℃、860℃、865℃)，保温时间为30-40h(比如32h、34h、36h、38h)。
在上述方法中，作为一种优选实施方式，在所述步骤四中，所述随炉冷却至不高于50℃(25℃、30℃、35℃、40℃、45℃)。高于50℃出炉，一方面磁体在热的状态易吸附周围环境中的湿气等，对磁性能不利，另一方面不利于炉体内加热元件，降低使用寿命，部分氧化后物理特性也发生了变化，导致炉体内温度分布有变化。
在上述方法中，作为一种优选实施方式，所述步骤五中，所述回火处理的温度为420-640℃(比如430℃、460℃、500℃、550℃、600℃、630℃)，时间为2-10h(比如3h、4h、6h、8h、9h)。在该回火制度下，利于富钕晶界相的形成和保持，超出该温度范围时，产品的性能会降低。更优选地，在所述步骤五中，所述回火处理的温度为420-480℃(比如425℃、 430℃、445℃、455℃、470℃)，时间为4-6h(比如4.5h、5h、5.5h)。
在上述方法中，所述步骤四中的处理设备可以为真空热处理炉。
在上述方法中，作为一种优选实施方式，在所述步骤五之后还包括后处理步骤：将所述稀土永磁材料在稀硝酸内浸泡去除表面残留的附着物，再用去离子水将所述稀土永磁材料清洗干净；优选地，所述稀硝酸为硝酸酒精溶液，质量浓度为2-10％(3％、4％、5％、6％、7％、8％、9％)，如果浓度过高，时间配合的窗口会很小，残留的可能性增加，如果浓度低的话，效率将降低；更优选质量浓度为4-6％；所述浸泡时间为60-180s(比如65s、70s、85s、100s、120s、145s、160s、170s、175s)。经回火处理后，磁体表面残留的附着物是非磁性的，会影响磁体性能，进行上述后处理除去该层物质能获得性能进一步提高的磁体，上述浸泡时间与膜厚有关。
与现有技术相比，本发明的有益效果是：
1)通过静电附着的方法将NdFeB基体和富含重稀土元素的化合物和纯金属粉末很好的结合在一起，经高温处理后，粉末膜内的重稀土化合物和纯金属粉末在磁体内扩散至主相和富钕相交界区域富集；通过这些处理的NdFeB磁体的矫顽力有显著提高，达到或超过了蒸镀、溅射等方法的效果。本发明提供的制备方法通过复合粉末有效的附着，适宜的热处理温度、时间，有效的时效温度和时间，改善了磁体晶界相及邻近区域的物理性质，使磁体的性能有显著提高，同时大大节约重稀土使用量；而传统方式主要是采用添加重稀土的方式来提高矫顽力，这种方式一方面会大幅降低剩磁，另一方面大量重稀土存在主相粒子内，因此需要重稀土的使用量较多。采用本发明提供的制备方法制备的稀土永磁材料NdFeB磁体的矫顽力可提高4000～14000Oe，剩磁仅降低1-2％，同等性能磁体可节约重稀土使用量30％。
2)传统的蒸镀、溅射需要的原料都是纯金属，与本发明中使用的氟化物或氧化物粉末相比较为昂贵，即，本发明中使用的原料为富含重稀土元素的化合物(氟化物或氧化物)，就是金属还原前的半成品，价格低，易于获得。传统的蒸镀、溅射工艺的附着都是一个简单的物理附着过程，需要一定的温度和真空条件；而本发明中，静电附着方法由于粉末和工件带不同的电荷，粉末和基体之间结合力更强，而且静电附着过程一旦结束，清扫后可以再使用，再者静电附着可在常温下进行，只需氮气保护。因此， 本发明为稀土永磁材料NdFeB性能的改善开辟了一条新颖的路线。采用本发明来改善磁体性能，一方面效率高、重稀土元素附着物和基体磁体结合力强；另一方面残余粉料回收方便，使用的重稀土量大幅降低，降低了产品的成本，使产品的性价比更具优势。
附图说明
图1为本发明的优选实施方式的技术流程图。
图2为本发明实施例1制备的稀土永磁材料的组织结构图；
图3为本发明实施例1中处理前后磁体的磁性能变化图，该图中横坐标Applied Field，即为外加磁场强度，纵坐标Magnetisation，即为磁化强度。
具体实施方式
为了使本发明的内容更容易被清楚的理解，下面根据本发明的具体实施例并结合附图，对本发明作进一步详细的说明。
以下实施例中使用的待处理的NdFeB磁体均为烧结NdFeB磁体，各实施例中使用不同牌号、不同批次商用的烧结钕铁硼磁体作为待处理磁体，本发明的方法适用于各种NdFeB磁体。静电附着采用的设备是静电喷粉线，生产厂家是固安科宇鑫鹏自动化控制设备有限公司，其中核心部件静电喷枪采用德国Wagner的喷枪。
图1给出了本发明方法的一种优选实施方式的工艺流程，具体包括如下步骤：磁体切割加工、磁体表面清理；粉末制备、粉末混合筛分；静电附着制备附着粉末膜的磁体；晶界扩散处理及时效；磁体表面加工。下面给出具体实施例。
实施例1
(1)按照粉末比例式(TbF 3) 95Nd 2Al 3配置复合粉末。称取TbF 3粉末，-150目；金属Nd粉末，-150目；金属Al粉末，-150目；将上述粉末混合均匀，并过150目筛分，粉末混合和过筛过程在氮气环境下进行。
(2)首先将商用50H牌号烧结NdFeB磁体机械加工成待处理形状，其中取向方向为1.96mm厚度；然后进入清理表面程序，清理表面程序如下： 将磁体放入除油槽中浸泡10min以去除磁体表面的油污，用清水洗净表面后用稀HNO 3(浓度为50wt％)酸洗20s，再经过水洗及超声波处理20s后，采用强风快速干燥磁体表面；从而得到待处理NdFeB磁体。
(3)在氮气环境下，步骤(1)制备的复合粉末，按照电压70kV，时间30s，喷枪移动速度20cm/s，喷射距离20cm的工艺条件通过喷枪带正电子；加速撞击到与阴极相连的步骤(2)得到的待处理NdFeB磁体上，从而得到表面附着复合粉末膜的NdFeB磁体，膜厚约40μm。
(4)将步骤(3)得到的表面附着复合粉末膜的NdFeB磁体放置在真空热处理炉内，真空度高于10 -3Pa，在850℃保温35小时；随炉冷却至不高于50℃，再经490℃回火处理6小时。
(5)将步骤(4)得到的磁体在稀硝酸(浓度为6wt％)内浸泡80s，去除磁体表面残留的附着物；用去离子水将磁体清洗干净，获得性能提高的磁体。
本实施例制备得到的稀土永磁材料的矫顽力提高14240Oe，剩磁稍有降低，降低了190Gs。处理前后磁体的性能变化(即将经步骤(2)得到的待处理NdFeB磁体和经步骤(3)、(4)、(5)处理后最终得到的永磁体进行进行性能测试，以后的实施例也是如此)如表1所示。本实施例制备得到的稀土永磁材料微观组织结构如图2所示，从该图中可以看出在主相颗粒周围包覆了一层均匀的、连续的晶界相，这将大大提高磁体在外加磁场时的去磁耦合能力，有利于磁体矫顽力的提高。图3为本发明的实施例1中处理前后磁体的性能变化图，从该图可以看出经过本实施例步骤(3)、(4)、(5)的技术处理，烧结钕铁硼的矫顽力从17740Oe提高到31980Oe，增加了14240Oe，剩磁稍有降低，即从13960Gs降低到13770G是，降低了190Gs。
实施例2
(1)按照粉末比例式(DyF 3) 95Nd 1Al 4配置复合粉末。称取DyF 3粉末，-150目；金属Nd粉末，-150目；金属Al粉末，-150目；将上述粉末混合均匀，并过150目筛分，粉末混合和过筛过程在氮气环境下进行。
(2)首先将商用48H牌号烧结NdFeB磁体机械加工成待处理形状，其中取向方向为3mm厚度；然后进入清理表面程序，清理表面程序如下： 将磁体放入除油槽中浸泡10min以去除磁体表面的油污，用清水洗净表面后用稀HNO 3酸洗20s，再经过水洗及超声波处理20s后，采用强风快速干燥磁体表面；从而得到待处理NdFeB磁体。
(3)在氮气环境下，步骤(1)制备的复合粉末，按照电压60kV，时间25s，喷枪移动速度20cm/s，喷射距离20cm的工艺条件通过喷枪带正电子，加速撞击到与阴极相连的步骤(2)得到的待处理NdFeB磁体上，从而得到表面附着复合粉末膜的NdFeB磁体，膜厚约30μm。
(4)将步骤(3)得到的表面附着复合粉末膜的NdFeB磁体放置在真空热处理炉内，真空度高于10 -3Pa，在830℃保温30小时；随炉冷却至不高于50℃，再经510℃回火处理4小时。
(5)将步骤(4)得到的磁体在稀硝酸(浓度为5.5wt％)内浸泡60s，去除磁体表面残留的附着物；用去离子水将磁体清洗干净，获得性能提高的磁体。
本实施例制备得到的稀土永磁材料的矫顽力提高7500Oe，剩磁稍有降低，降低了175Gs。处理前后磁体性能变化如表1所示。
实施例3
(1)按照粉末比例式(TbF 3) 95Cu 5配置复合粉末。称取TbF 3粉末，-150目；金属Cu粉末，-150目；将上述粉末混合均匀，并过150目筛分，粉末混合和过筛过程在氮气环境下进行。
(2)首先将商用42M牌号烧结NdFeB磁体机械加工成待处理形状，其中取向方向为5mm厚度；然后进入清理表面程序，清理表面程序如下：将磁体放入除油槽中浸泡10min以去除磁体表面的油污，用清水洗净表面后用稀HNO 3酸洗35s，再经过水洗及超声波处理35s后，采用强风快速干燥磁体表面；从而得到待处理NdFeB磁体。
(3)在氮气环境下，步骤(1)制备的复合粉末，按照电压60kV，时间25s，喷枪移动速度20cm/s，喷射距离20cm的工艺条件通过喷枪带正电子，加速撞击到与阴极相连的步骤(2)得到的待处理NdFeB磁体上，从而得到表面附着复合粉末膜的NdFeB磁体，膜厚约30μm。
(4)将步骤(3)得到的表面附着复合粉末膜的NdFeB磁体放置在真空热处理炉内，真空度高于10 -3Pa，在860℃保温35小时；随炉冷却至不 高于50℃，再经500℃回火处理6小时。
(5)将步骤(4)得到的磁体在稀硝酸(浓度为6.5wt％)内浸泡100s，去除磁体表面残留的附着物；用去离子水将磁体清洗干净，获得性能提高的磁体。
本实施例制备得到的稀土永磁材料的矫顽力提高12000Oe，剩磁稍有降低，降低了180Gs。处理前后磁体性能变化如表1所示。
实施例4
(1)按照粉末比例式(HoF 3) 97Pr 1Cu 2配置复合粉末。称取HoF 3粉末，-150目；金属Pr粉末，-150目；金属Cu粉末，-150目；将上述粉末混合均匀，并过150目筛分，粉末混合和过筛过程在氮气环境下进行。
(2)首先将商用42M牌号烧结NdFeB磁体机械加工成待处理形状，其中取向方向为3mm厚度；然后进入清理表面程序，清理表面程序如下：将磁体放入除油槽中浸泡10min以去除磁体表面的油污，用清水洗净表面后用稀HNO 3酸洗25s，再经过水洗及超声波处理25s后，采用强风快速干燥磁体表面；从而得到待处理NdFeB磁体。
(3)在氮气环境下，步骤(1)制备的复合粉末，按照电压50kV，时间15s，喷枪移动速度25cm/s，喷射距离20cm的工艺条件通过喷枪带正电子，加速撞击到与阴极相连的步骤(2)得到的待处理NdFeB磁体上，从而得到表面附着复合粉末膜的NdFeB磁体，膜厚约25μm。
(4)将步骤(3)得到的表面附着复合粉末膜的NdFeB磁体放置在真空热处理炉内，真空度高于10 -3Pa，在850℃保温35小时；随炉冷却至不高于50℃，再经480℃回火处理4小时。
(5)将步骤(4)得到的磁体在稀硝酸(浓度为5.5wt％)内浸泡60s，去除磁体表面残留的附着物；用去离子水将磁体清洗干净，获得性能提高的磁体。
本实施例制备得到的稀土永磁材料的矫顽力提高4000Oe，剩磁稍有降低，降低了210Gs。处理前后磁体性能变化如表1所示。
实施例5
(1)按照粉末比例式((DyTb)F 3) 96Cu 1Al 3配置复合粉末。称取(DyTb) F 3粉末，-150目；金属Cu粉末，-150目；金属Al粉末，-150目；将上述粉末混合均匀，并过150目筛分，粉末混合和过筛过程在氮气环境下进行。
(2)首先将商用52SH牌号烧结NdFeB磁体机械加工成待处理形状，其中取向方向为6mm厚度；然后进入清理表面程序，清理表面程序如下：将磁体放入除油槽中浸泡10min以去除磁体表面的油污，用清水洗净表面后用稀HNO 3酸洗45s，再经过水洗及超声波处理45s后，采用强风快速干燥磁体表面；从而得到待处理NdFeB磁体。
(3)在氩气环境下，步骤(1)制备的复合粉末，按照电压65kV，时间28s，喷枪移动速度20cm/s，喷射距离18cm的工艺条件通过喷枪带正电子，加速撞击到与阴极相连的步骤(2)得到的待处理NdFeB磁体上，从而得到表面附着复合粉末膜的NdFeB磁体，膜厚约30μm。
(4)将步骤(3)得到的表面附着复合粉末膜的NdFeB磁体放置在真空热处理炉内，真空度高于10 -3Pa，在870℃保温40小时；随炉冷却至不高于50℃，再经520℃回火处理6小时。
(5)将步骤(4)得到的磁体在稀硝酸(浓度为6wt％)内浸泡90s，去除磁体表面残留的附着物；用去离子水将磁体清洗干净，获得性能提高的磁体。
本实施例制备得到的稀土永磁材料的矫顽力提高11000Oe，剩磁稍有降低，降低了168Gs。处理前后磁体性能变化如表1所示。
实施例6
(1)按照粉末比例式(GdF 3) 98Cu 2配置复合粉末。称取GdF 3粉末，-150目；金属Cu粉末，-150目；将上述粉末混合均匀，并过150目筛分，粉末混合和过筛过程在氮气环境下进行。
(2)首先将商用35M+牌号烧结NdFeB磁体机械加工成待处理形状，其中取向方向为3mm厚度；然后进入清理表面程序，清理表面程序如下：将磁体放入除油槽中浸泡10min以去除磁体表面的油污，用清水洗净表面后用稀HNO 3酸洗25s，再经过水洗及超声波处理25s后，采用强风快速干燥磁体表面；从而得到待处理NdFeB磁体。
(3)在氩气环境下，步骤(1)制备的复合粉末，按照电压65kV，时间25s，喷枪移动速度20cm/s，喷射距离20cm的工艺条件通过喷枪带正电 子，加速撞击到与阴极相连的步骤(2)得到的待处理NdFeB磁体上，从而得到表面附着复合粉末膜的NdFeB磁体，膜厚约35μm。
(4)将步骤(3)得到的表面附着复合粉末膜的NdFeB磁体放置在真空热处理炉内，真空度高于10 -3Pa，在840℃保温35小时；随炉冷却至不高于50℃，再经490℃回火处理4小时。
(5)将步骤(4)得到的磁体在稀硝酸(浓度为5wt％)内浸泡60s，去除磁体表面残留的附着物；用去离子水将磁体清洗干净，获得性能提高的磁体。
本实施例制备得到的稀土永磁材料的矫顽力提高4200Oe，剩磁稍有降低，降低了208Gs。处理前后磁体性能变化如表1所示。
实施例7
(1)按照粉末比例式(TbO 3) 94Nd 1Al 5配置复合粉末。称取TbO 3粉末，-150目；金属Nd粉末，-150目；金属Al粉末，-150目；将上述粉末混合均匀，并过150目筛分，粉末混合和过筛过程须氮气环境下进行。
(2)首先将商用48H+牌号烧结NdFeB磁体机械加工成待处理形状，其中取向方向为8mm厚度；然后进入清理表面程序，清理表面程序如下：将磁体放入除油槽中浸泡10min以去除磁体表面的油污，用清水洗净表面后用稀HNO 3酸洗45s，再经过水洗及超声波处理45s后，采用强风快速干燥磁体表面；从而得到待处理NdFeB磁体。
(3)在氩气环境下，步骤(1)制备的复合粉末，按照电压75kV，时间30s，喷枪移动速度20cm/s，喷射距离20cm的工艺条件通过喷枪带正电子，加速撞击到与阴极相连的步骤(2)得到的待处理NdFeB磁体上，从而得到表面附着复合粉末膜的NdFeB磁体，膜厚约40μm。
(4)将步骤(3)得到的表面附着复合粉末膜的NdFeB磁体放置在真空热处理炉内，真空度高于10 -3Pa，在860℃保温40小时；随炉冷却至不高于50℃，再经490℃回火处理5小时。
(5)将步骤(4)得到的磁体在稀硝酸(浓度为8wt％)内浸泡180s，去除磁体表面残留的附着物；用去离子水将磁体清洗干净，获得性能提高的磁体。
本实施例制备得到的稀土永磁材料的矫顽力提高8000Oe，剩磁稍有降 低，降低了185Gs。处理前后磁体性能变化如表1所示。
实施例8
(1)按照粉末比例式(DyO 3) 97(PrNd) 2Al 1配置复合粉末。称取DyO 3粉末，-150目；金属PrNd粉末(Pr和Nd的质量比为1:4)，-150目；金属Al粉末，-150目；将上述粉末混合均匀，并过150目筛分，粉末混合和过筛过程在氮气环境下进行。
(2)首先将商用42M牌号烧结NdFeB磁体机械加工成待处理形状，其中取向方向为6mm厚度；然后进入清理表面程序，清理表面程序如下：将磁体放入除油槽中浸泡10min以去除磁体表面的油污，用清水洗净表面后用稀HNO 3酸洗45s，再经过水洗及超声波处理45s后，采用强风快速干燥磁体表面；从而得到待处理NdFeB磁体。
(3)在氩气环境下，步骤(1)制备的复合粉末，按照电压75kV，时间30s，喷枪移动速度18cm/s，喷射距离22cm的工艺条件通过喷枪带正电子，加速撞击到与阴极相连的步骤(2)得到的待处理NdFeB磁体上，从而得到表面附着复合粉末膜的NdFeB磁体，膜厚约40μm。
(4)将步骤(3)得到的表面附着复合粉末膜的NdFeB磁体放置在真空热处理炉内，真空度高于10 -3Pa，在830℃保温40小时；随炉冷却至不高于50℃，再经490℃回火处理6小时。
(5)将步骤(4)得到的磁体在稀硝酸(浓度为7wt％)内浸泡120s，去除磁体表面残留的附着物；用去离子水将磁体清洗干净，获得性能提高的磁体。
本实施例制备得到的稀土永磁材料的矫顽力提高6500Oe，剩磁稍有降低，降低了190Gs。处理前后磁体性能变化如表1所示。
实施例9
(1)按照粉末比例式(TbF 3) 46(DyO 3) 48Nd 2ZnSnCu 2配置复合粉末。称取TbF 3和DyO 3粉末，-150目；金属Nd粉末，-150目；金属Zn、Sn、Cu粉末，-150目；将上述粉末混合均匀，并过150目筛分，粉末混合和过筛过程在氮气环境下进行。
(2)首先将商用46UH牌号烧结NdFeB磁体机械加工成待处理形状， 其中取向方向为4.5mm厚度；然后进入清理表面程序，清理表面程序如下：将磁体放入除油槽中浸泡10min以去除磁体表面的油污，用清水洗净表面后用稀HNO 3酸洗30s，再经过水洗及超声波处理30s后，采用强风快速干燥磁体表面；从而得到待处理NdFeB磁体。
(3)在氩气环境下，步骤(1)制备的复合粉末，按照电压70kV，时间25s，喷枪移动速度18cm/s，喷射距离22cm的工艺条件通过喷枪带正电子，加速撞击到与阴极相连的步骤(2)得到的待处理NdFeB磁体上，从而得到表面附着复合粉末膜的NdFeB磁体，膜厚约30μm。
(4)将步骤(3)得到的表面附着复合粉末膜的NdFeB磁体放置在真空热处理炉内，真空度高于10 -3Pa，在845℃保温30小时；随炉冷却至不高于50℃，再经490℃回火处理6小时。
(5)将步骤(4)得到的磁体在稀硝酸(浓度为5.0wt％)内浸泡80s，去除磁体表面残留的附着物；用去离子水将磁体清洗干净，获得性能提高的磁体。
本实施例制备得到的稀土永磁材料的矫顽力提高8500Oe，剩磁稍有降低，降低了170Gs。处理前后磁体性能变化如表1所示。
表1 实施例1-9中磁体处理前后的性能检测结果
Figure PCTCN2018080650-appb-000001
实施例10-13
实施例10-13除复合粉末膜厚度不同于实施例2外，其他工艺参数都 与实施例2相同；其中，实施例10中复合粉末膜厚度约为12μm，实施例11中复合粉末膜厚度约为20μm，实施例12中复合粉末膜厚度约为5μm，实施例13中复合粉末膜厚度约为45μm。处理前后磁体性能变化如表2所示。
实施例14-15
实施例14-15除第(4)步骤真空热处理中保温温度和保温时间不同于实施例2外，其他工艺参数都与实施例2相同；其中，实施例14中真空热处理条件为：1000℃保温10h，实施例15中真空热处理条件为：700℃保温48h。处理前后磁体性能变化如表2所示。
实施例16-17
实施例16-17除第(4)步骤回火处理温度和时间不同于实施例2外，其他工艺参数都与实施例2相同；其中，实施例16中回火处理条件为：430℃回火处理8h，实施例17中回火处理条件为：640℃回火处理2h。处理前后磁体性能变化如表2所示。
表2 实施例10-17中磁体处理前后的性能检测结果
Figure PCTCN2018080650-appb-000002
实施例18-23
实施例18-23除所用复合粉末组成不同于实施例2外，其他工艺参数都与实施例2相同；具体的复合粉末组成以及处理前后磁体性能变化如表3所示。
表3 实施例18-23中磁体处理前后的性能检测结果
Figure PCTCN2018080650-appb-000003
显然，上述实施例仅仅是为清楚地说明所作的举例，而并非对实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式的变化或变动。这里无需也无法对所有的实施方式予以穷举。而由此所引伸出的显而易见的变化或变动仍处于本发明创造的保护范围之中。

Claims (14)

  1. 一种稀土永磁材料的制备方法，其特征在于，包括如下操作步骤：
    步骤一，按照通式H 100-x-yM xQ y中的原子百分比含量称取H、M、Q三种原料粉末，在氮气或其他无氧环境下将所述三种原料依次进行混合处理和过筛处理，得到复合粉末；所述通式中，H为Dy、Tb、DyTb、Ho、Gd的氟化物或氧化物粉末中的一种或多种，M为Nd或/和Pr金属粉末，Q为Cu、Al、Zn、Ga和Sn金属粉末中的一种或多种，x、y分别为原料M和原料Q的原子百分含量，x＝0-20、y＝0-40，且x和y不同时为零；
    步骤二，将烧结NdFeB磁体机械加工成规定形状和尺寸，随后进行表面清理及干燥，从而得到待处理NdFeB磁体；
    步骤三，在无氧的环境下，将所述复合粉末通过静电附着于所述待处理NdFeB磁体的表面，得到表面附着复合粉末膜的NdFeB磁体；
    步骤四，将所述表面附着复合粉末膜的NdFeB磁体进行真空热处理，之后随炉冷却，从而得到扩散后的NdFeB磁体；
    步骤五，将所述扩散后的NdFeB磁体进行回火处理，从而得到所述稀土永磁材料。
  2. 根据权利要求1所述的稀土永磁材料的制备方法，其特征在于，在所述步骤一中，所述通式中x＝1-15、y＝4-25。
  3. 根据权利要求1所述的稀土永磁材料的制备方法，其特征在于，在所述步骤一中，M为PrNd金属粉末，Pr和Nd质量比为1:2-1:5。
  4. 根据权利要求1所述的稀土永磁材料的制备方法，其特征在于，在所述步骤一中，所述原料粉末粒度为-150目，所述过筛处理为过150目筛。
  5. 根据权利要求1所述的稀土永磁材料的制备方法，其特征在于，在所述步骤二中，所述待处理NdFeB磁体的取向方向厚度为1-8mm；优选地，所述表面清理的过程如下：首先将所述烧结NdFeB磁体放入除油槽中浸泡8-15min以去除磁体表面的油污；然后依次经第一次水洗、酸洗、第二次水 洗及超声波处理，最后风干所述烧结NdFeB磁体表面；更优选地，所述酸洗采用稀HNO 3酸洗、时间为20-45s，所述超声波处理的时间为20-45s，所述风干采用强风快速干燥。
  6. 根据权利要求1所述的稀土永磁材料的制备方法，其特征在于，在所述步骤三中，所述复合粉末膜厚度为10-40μm；优选地，所述复合粉末膜厚度为25-40μm。
  7. 根据权利要求1所述的稀土永磁材料的制备方法，其特征在于，在所述步骤三中，将所述复合粉末通过静电喷枪喷射于所述待处理NdFeB磁体的表面，其中，工艺条件如下：
    电压为30-120kv，优选为50-90kv；
    时间为5-40s，优选为15-30s；
    喷枪移动速度5-45cm/s，优选为10-30cm/s；
    喷射距离8-35cm，优选为15-25cm。
  8. 根据权利要求1所述的稀土永磁材料的制备方法，其特征在于，在所述步骤四中，所述真空热处理的条件如下：真空度高于10 -3Pa，保温温度为650-1050℃，保温时间为5-50h。
  9. 根据权利要求8所述的稀土永磁材料的制备方法，其特征在于，所述保温温度为830-870℃，保温时间为30-40h；所述随炉冷却至不高于50℃。
  10. 根据权利要求1所述的稀土永磁材料的制备方法，其特征在于，所述步骤五中，所述回火处理的温度为420-640℃，时间为2-10h。
  11. 根据权利要求10所述的稀土永磁材料的制备方法，其特征在于，所述回火处理的温度为420-480℃，时间为4-6h。
  12. 根据权利要求1-11中任一项所述的稀土永磁材料的制备方法，其 特征在于，在所述步骤五之后还包括后处理步骤：将所述稀土永磁材料在稀硝酸内浸泡去除表面残留的附着物，再用去离子水将所述稀土永磁材料清洗干净。
  13. 根据权利要求12所述的稀土永磁材料的制备方法，其特征在于，所述稀硝酸为硝酸酒精溶液，质量浓度为2-10％，所述浸泡时间为60-180s。
  14. 根据权利要求13所述的稀土永磁材料的制备方法，其特征在于，所述硝酸酒精溶液的质量浓度为4-6％。
PCT/CN2018/080650 2017-04-19 2018-03-27 一种稀土永磁材料的制备方法 WO2018192346A1 (zh)

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