WO2019029000A1 - 一种耐高温钕铁硼磁体及其制备方法 - Google Patents

一种耐高温钕铁硼磁体及其制备方法 Download PDF

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Publication number
WO2019029000A1
WO2019029000A1 PCT/CN2017/106066 CN2017106066W WO2019029000A1 WO 2019029000 A1 WO2019029000 A1 WO 2019029000A1 CN 2017106066 W CN2017106066 W CN 2017106066W WO 2019029000 A1 WO2019029000 A1 WO 2019029000A1
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Prior art keywords
powder
iron boron
neodymium iron
rare earth
magnet
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PCT/CN2017/106066
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English (en)
French (fr)
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毛华云
刘路军
詹益街
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江西金力永磁科技股份有限公司
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Priority to JP2018566865A priority Critical patent/JP2019535121A/ja
Priority to EP17911402.0A priority patent/EP3667685A4/en
Priority to US16/315,123 priority patent/US20210296028A1/en
Publication of WO2019029000A1 publication Critical patent/WO2019029000A1/zh

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    • 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
    • H01F1/0576—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 pressed, e.g. hot working
    • 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

Definitions

  • the invention belongs to the field of rare earth permanent magnet materials, relates to a neodymium iron boron magnet and a preparation method thereof, in particular to a high temperature resistant neodymium iron boron magnet and a preparation method thereof.
  • Neodymium iron boron magnet also known as neodymium magnet
  • Nd 2 Fe 14 B has a chemical formula of Nd 2 Fe 14 B. It is an artificial permanent magnet and is the permanent magnet with the strongest magnetic force so far. Its maximum magnetic energy product (BHmax) is high. Ten times more than ferrite, in the bare magnetic state, its magnetic force can reach about 3500 Gauss.
  • BHmax maximum magnetic energy product
  • the industry often uses the sintering method to make NdFeB permanent magnet materials. For example, Wang Wei et al. disclose the influence of key process parameters and alloying elements on the magnetic properties and mechanical properties of sintered NdFeB.
  • the material process generally includes the steps of batching, smelting, ingot crushing, milling, hydrogen crushing ultrafine powder, powder orientation press molding, vacuum sintering, scribing and electroplating.
  • the advantages of NdFeB magnets are high cost performance, small size, light weight, good mechanical properties and strong magnetic properties.
  • the advantages of such high energy density make NdFeB permanent magnet materials widely available in modern industrial and electronic technologies.
  • Application known as the magnetic king in the field of magnetism. Therefore, the preparation and expansion of NdFeB magnets has been the focus of continuous attention in the industry.
  • R-Fe-B rare earth sintered magnets with Nd 2 Fe 14 B type compounds as the main phase have been used as the most powerful magnets in permanent magnets, and are widely used in hard disk driven voice coil motors (VCM).
  • VCM hard disk driven voice coil motors
  • Servo motors, inverter air conditioner motors, and motors for hybrid vehicles are used.
  • magnets are required to have high coercivity characteristics, and in order to adapt to high-temperature use environments, they are required to have excellent heat resistance.
  • the conventional method is mainly to add the rare earth element RH as a raw material, so that the light rare earth elements RL (mainly Nd and Pr) in the R 2 Fe 14 B phase are Since the heavy rare-earth element RH is substituted, the crystal magnetic anisotropy (physical quantity determining the nature of the coercive force) of the R 2 Fe 14 B phase is improved.
  • the magnetic moment of the light rare earth element RL in the R 2 Fe 14 B phase is higher than that of the rare earth element RH. Therefore, the replacement of the light rare earth element RL with the heavy rare earth element RH results in a residual magnetic flux density Br. decline.
  • the heavy rare-earth element RH is a scarce resource, it is highly desirable to reduce the amount of its use.
  • the percolation technology has also received extensive attention in the industry, that is, coating, depositing, plating, sputtering or adhering on the surface of the magnet, applying heavy rare earth elements, and then infiltrating; or by evaporation After heavy rare earth, a layer of heavy rare earth metal is plated on the surface of the magnet and then infiltrated.
  • the percolation technique causes the powder of the metal or compound containing Dy to adhere to the outer surface of the magnet as a diffusion source, and then performs diffusion heat treatment in a certain temperature range to diffuse the rare earth element along the grain boundary to the surface layer of the main phase crystal, thereby improving The anisotropy field of the grain surface, the grain boundary microstructure is improved, and the coercive force of the magnet is improved.
  • the percolation technique has a small diffusion thickness during the diffusion process of the high-temperature heat treatment, and the performance change of the magnet is limited.
  • the technical problem to be solved by the present invention is to provide a neodymium iron boron magnet and a preparation method thereof, in particular to a high temperature resistant neodymium iron boron magnet, and the NdFeB magnet provided by the invention has better high temperature correction. It is tenacious and has balanced magnetic properties. At the same time, the preparation method is simple and easy, and it is suitable for large-scale industrial production.
  • the invention provides a neodymium iron boron magnet obtained by preparing a neodymium iron boron raw material powder coated with a modified powder;
  • the modified powder includes a heavy rare earth oxide powder and/or a heavy rare earth fluoride powder.
  • the ratio of the average particle diameter of the NdFeB raw material powder to the average particle diameter of the modified powder is (50 to 200):1.
  • the heavy rare earth element comprises cerium and/or cerium.
  • the ratio of the modified powder to the total mass of the neodymium iron boron magnet is 4% or less.
  • each component of the NdFeB raw material powder is composed of mass percentage, including: Pr-Nd: 28% to 33%; Dy: 0 to 10%; Tb: 0 to 10%; and Nb: 0 to 5%.
  • B 0.5% to 2.0%; Al: 0 to 3.0%; Cu: 0 to 1%; Co: 0 to 3%; Ga: 0 to 2%; Gd: 0 to 2%; Ho: 0 to 2% ;Zr: 0 to 2%; the balance is Fe.
  • the NdFeB raw material powder comprises a finished magnetic material prepared by using only NdFeB raw material powder.
  • the intrinsic coercive force of the body is greater than or equal to the medium-high coercive magnet raw material powder of 17 kOe.
  • the invention also provides a preparation method of a neodymium iron boron magnet, comprising the following steps:
  • the modified powder includes a heavy rare earth oxide powder and/or a heavy rare earth fluoride powder
  • the high-speed mixing time is 0.1 to 2 hours;
  • the high speed mixing speed is 80 to 220 rpm.
  • the sintering temperature is 1030 ⁇ 1090 ° C;
  • the sintering time is 3 to 10 hours
  • the sintering also includes an aging treatment step.
  • the aging treatment specifically includes a primary annealing aging treatment and a secondary annealing aging treatment;
  • the temperature of the first-stage annealing aging treatment is 800-950 ° C; the time of the first-stage annealing aging treatment is 3-10 hours;
  • the temperature of the secondary annealing aging treatment is 400 to 550 ° C; and the time of the secondary annealing aging treatment is 3 to 10 hours.
  • the present invention provides a neodymium iron boron magnet obtained by preparing a neodymium iron boron raw material powder coated with a modified powder comprising a heavy rare earth oxide and/or a heavy rare earth fluoride.
  • the present invention is directed to the replacement of light rare earth elements by existing heavy rare earth elements, resulting in a decrease in residual magnetic flux density Br, a large amount of defects, and the percolation technique also has a small diffusion thickness, and the performance of the magnet is limited. The problem.
  • the invention is creatively started from the aspect of the magnet powder, in particular, the heavy rare earth fluoride or oxide is coated on the surface of the magnetic powder particles, so that the diffusion can be simultaneously performed during the subsequent sintering of the magnet, and
  • the powder of heavy rare earth oxide or fluoride coated on the surface of the magnetic powder particles replaces part of the light rare earth during the sintering process, and the heavy rare earth is absorbed by the magnet, thereby increasing the coercive force and effectively suppressing the decrease of the residual magnetism.
  • the invention adopts heavy rare earth oxide or fluoride as a diffusion source to coat the surface of the magnetic powder particles before sintering, and adopts a small amount of heavy rare earth material, which can significantly improve the coercive force of the magnet and save heavy rare earth. Resources save production costs.
  • the invention is simpler than the existing diffusion and percolation process, and the size of the magnet is not limited.
  • the experimental results show that the NdFeB magnets with modified powders of the present invention have an improvement of coercivity of the magnets by 85%, and the remanence and maximum energy product performance are basically stable.
  • All the raw materials of the present invention are not particularly limited in their source, and are commercially available or prepared according to a conventional method well known to those skilled in the art.
  • the purity of all the raw materials of the present invention is not particularly limited, and the present invention preferably employs a conventional purity used in the field of analytically pure or neodymium iron boron magnets.
  • the invention provides a neodymium iron boron magnet obtained by preparing a neodymium iron boron raw material powder coated with a modified powder;
  • the modified powder includes a heavy rare earth oxide powder and/or a heavy rare earth fluoride powder.
  • the heavy rare earth element of the present invention is not particularly limited, and a heavy rare earth element for a magnet material well known to those skilled in the art may be used, and those skilled in the art may select and adjust according to actual production conditions, product requirements, and quality requirements.
  • the heavy rare earth element of the present invention preferably comprises cerium and/or cerium, more preferably cerium or lanthanum.
  • the heavy rare earth oxide of the present invention is not particularly limited, and a heavy rare earth oxide for a magnet material well known to those skilled in the art may be used, and those skilled in the art may select and according to actual production conditions, product requirements, and quality requirements.
  • the heavy rare earth oxide of the present invention preferably comprises Dy 2 O 3 , Tb 2 O 3 or Tb 4 O 7 , more preferably Dy 2 O 3 or Tb 2 O 3 .
  • the heavy rare earth fluoride of the present invention is not particularly limited, and a heavy rare earth fluoride for a magnet material well known to those skilled in the art may be used, and those skilled in the art can select and according to actual production conditions, product requirements, and quality requirements.
  • the heavy rare earth fluoride of the present invention preferably comprises DyF 3 or TbF 3 .
  • the amount of the modified powder to be added in the present invention is not particularly limited, and the amount of such a material for a magnet material well known to those skilled in the art may be sufficient, and those skilled in the art may be based on actual production conditions, product requirements, and quality. Selection and adjustment are required, the modified powder occupies the neodymium iron boron magnet
  • the ratio of the total mass is preferably 4% or less, more preferably 0.01% to 4%, still more preferably 0.1% to 3.5%, still more preferably 1% to 3%, still more preferably 1.5% to 2.5%.
  • the particle size of the modified powder is not particularly limited in the present invention, and the conventional particle diameter for the magnet material well known to those skilled in the art may be selected, and those skilled in the art may select according to actual production conditions, product requirements, and quality requirements.
  • the modified powder of the present invention is preferably a nano-sized modified powder, and the specific particle diameter is more preferably from 10 to 300 nm, still more preferably from 20 to 250 nm, still more preferably from 30 to 200 nm, still more preferably from 50 to 150 nm, more It is preferably 60 to 100 nm.
  • the average particle diameter of the NdFeB raw material powder and the average particle diameter ratio of the modified powder are not particularly limited, and the conventional particle diameter ratio for the magnet material well known to those skilled in the art can be used, and those skilled in the art can be used.
  • the invention can be selected and adjusted according to actual production conditions, product requirements and quality requirements. In order to improve the coating effect and thereby ensure the magnetic properties of the product, the average particle diameter of the NdFeB raw material powder and the average particle of the modified powder can be adjusted.
  • the ratio of the diameter is preferably (50 to 200): 1, more preferably (75 to 175): 1, and most preferably (100 to 150): 1.
  • the definition of the average particle diameter in the present invention is not particularly limited, and can be defined by a conventional average particle diameter for a magnet material well known to those skilled in the art, and can be carried out by those skilled in the art according to actual production conditions, product requirements, and quality requirements.
  • the average particle diameter of the present invention preferably refers to an area average particle diameter (SMD).
  • composition of the NdFeB raw material powder of the present invention is not particularly limited, and the composition of the NdFeB raw material powder well known to those skilled in the art may be used, and those skilled in the art may have factors such as actual application conditions, product requirements, and quality requirements.
  • the components of the NdFeB raw material powder of the present invention are composed by mass percentage, and preferably include: Pr-Nd: 28% to 33%, Dy: 0 to 10%, Tb: 0 to 10%, Nb.
  • the specific grade of the NdFeB magnet raw material is not particularly limited, and the conventional grade of the NdFeB magnet well known to those skilled in the art may be used, and those skilled in the art may according to actual application conditions, product requirements, quality requirements, etc. Selection and adjustment of factors, the NdFeB raw material powder of the present invention
  • the present invention includes a magnet having a medium-high coercive force with an intrinsic coercive force of 17 kOe or more, that is, a normal magnet prepared by using a pure NdFeB raw material powder before adding a modified powder.
  • a magnet having a medium-high coercive force with an intrinsic coercive force of 17 kOe or more may include a (medium coercive force) M-type NdFeB magnet, a (high coercive force) H-type NdFeB magnet, High coercivity) SH-based NdFeB magnets, (ultra-high coercivity) UH-based NdFeB magnets or (very high coercivity), EH NdFeB magnets or AH NdFeB magnets
  • the invention preferably uses a H-type NdFeB magnet raw material, a SH-based NdFeB magnet raw material or a UH NdFeB magnet raw material, more preferably a SH-based NdFeB magnet raw material, and specifically, a 42SH, 45SH or 40UH grade can be used.
  • the neodymium iron boron magnet is specifically preferably 42SH.
  • the invention also provides a preparation method of a neodymium iron boron magnet, comprising the following steps:
  • the modified powder includes a heavy rare earth oxide powder and/or a heavy rare earth fluoride powder
  • the selection and optimization principles regarding the raw materials, the ratio, and other parameters are consistent with the selection and optimization principles of the raw materials, ratios, and other parameters in the foregoing neodymium iron boron magnet, and will not be further described herein.
  • the crushed NdFeB raw material powder and the modified powder are first mixed at a high speed to obtain a modified NdFeB raw material powder.
  • the crushed NdFeB raw material powder of the present invention is not particularly limited, and the NdFeB raw material powder in the preparation process of the conventional NdFeB magnet well known to those skilled in the art may be used, and those skilled in the art may according to actual production conditions. The product requirements and the quality requirements are selected and adjusted.
  • the crushed NdFeB raw material powder of the present invention preferably refers to the NdFeB material after one or more steps such as batching, smelting, crushing, milling and hydrogen crushing. NdFeB raw material fine powder.
  • the particle size of the NdFeB raw material powder is not particularly limited in the present invention, and the conventional particle size for magnet preparation well known to those skilled in the art may be used, and those skilled in the art may according to actual production conditions, product requirements, and quality requirements.
  • the NdFeB raw material powder of the present invention preferably has an average particle diameter of 1.0 to 5.0 ⁇ m, more preferably 1.5 to 4.5 ⁇ m, still more preferably 2.0 to 3.0 ⁇ m.
  • the time for the high-speed mixing of the present invention is not particularly limited, and the conventional mixing time is well known to those skilled in the art, and those skilled in the art can select and adjust according to actual production conditions, product requirements, and quality requirements.
  • the time for high-speed mixing is preferably from 0.1 to 2 hours, more preferably from 0.5 to 1.5 hours, still more preferably from 5 to 60 minutes, still more preferably from 20 to 45 minutes.
  • the speed of the high-speed mixing of the present invention is not particularly limited, and can be selected and adjusted according to actual production conditions, product requirements, and quality requirements by those skilled in the art.
  • the rotation speed of the high speed mixing is preferably from 80 to 220 rpm, more preferably from 100 to 200 rpm, still more preferably from 120 to 180 rpm.
  • the particle size of the modified NdFeB raw material powder is not particularly limited, and the conventional particle size for magnet preparation well known to those skilled in the art may be used, and those skilled in the art may according to actual production conditions, product requirements, and
  • the quality of the modified NdFeB raw material powder of the present invention is preferably 1.0 to 5.0 ⁇ m, more preferably 1.5 to 4.5 ⁇ m, still more preferably 2.0 to 3.0 ⁇ m.
  • the pressing method of the invention is not particularly limited, and the method of pressing the NdFeB raw material powder well known to those skilled in the art may be used, and those skilled in the art may select and adjust according to actual production conditions, product requirements and quality requirements.
  • the pressing of the invention preferably comprises oriented pressing and isostatic pressing, more preferably oriented pressing under the protection of nitrogen or an inert gas, followed by oil isostatic pressing.
  • the sintering time of the present invention is not particularly limited, and the sintering time of the neodymium iron boron magnet well known to those skilled in the art can be used. Those skilled in the art can select and adjust according to actual production conditions, product requirements and quality requirements.
  • the sintering time of the invention is preferably from 3 to 10 hours, more preferably from 4 to 9 hours, still more preferably from 5 to 8 hours, and most preferably from 6 to 7 hours.
  • the temperature of the sintering is not particularly limited in the present invention, and the sintering temperature of the neodymium iron boron magnet well known to those skilled in the art may be used, and those skilled in the art may select and adjust according to actual production conditions, product requirements, and quality requirements.
  • the sintering temperature of the invention is preferably from 1030 to 1090 ° C, more preferably from 1040 to 1080 ° C, and most preferably from 1050 to 1070 ° C.
  • the present invention preferably improves the magnetic properties of the product, completes and optimizes the process flow, and preferably includes an aging treatment step after sintering.
  • the specific process and steps of the aging treatment of the present invention are not particularly limited, and those skilled in the art
  • the heat treatment-like process is well known, and the aging treatment of the present invention specifically preferably includes a primary annealing aging treatment and a secondary annealing aging treatment.
  • the specific temperature of the first-stage annealing aging treatment is not particularly limited, and the aging treatment temperature is well known to those skilled in the art, and those skilled in the art can select and adjust according to actual production conditions, product requirements, and quality requirements.
  • the temperature of the primary annealing aging treatment of the present invention is preferably 800 to 950 ° C, more preferably 825 to 925 ° C, and most preferably 850 to 900 ° C.
  • the specific time for the first-stage annealing aging treatment of the present invention is not particularly limited, and the aging treatment time is well known to those skilled in the art, and those skilled in the art can select and adjust according to actual production conditions, product requirements, and quality requirements.
  • the time of the primary annealing aging treatment of the present invention is preferably from 3 to 10 hours, more preferably from 4 to 9 hours, still more preferably from 5 to 8 hours, and most preferably from 6 to 7 hours.
  • the specific temperature of the secondary annealing aging treatment of the present invention is not particularly limited, and the aging treatment temperature is well known to those skilled in the art, and those skilled in the art can select and adjust according to actual production conditions, product requirements, and quality requirements.
  • the temperature of the secondary annealing aging treatment of the present invention is preferably from 400 to 550 ° C, more preferably from 425 to 525 ° C, and most preferably from 450 to 500 ° C.
  • the specific time for the secondary annealing aging treatment of the present invention is not particularly limited, and the aging treatment time is well known to those skilled in the art, and those skilled in the art can select and adjust according to actual production conditions, product requirements, and quality requirements.
  • the time of the secondary annealing aging treatment of the present invention is preferably from 3 to 10 hours, more preferably from 4 to 9 hours, still more preferably from 5 to 8 hours, and most preferably from 6 to 7 hours.
  • the other conditions of the sintering and aging treatment of the present invention are not particularly limited, and the conditions of the sintering and aging treatment of the magnets well known to those skilled in the art may be used.
  • the present invention is to improve the effect of the heat treatment process, and is also preferably in a protective atmosphere or vacuum. Sintering and aging treatment are carried out.
  • the apparatus for sintering and aging treatment of the present invention is not particularly limited, and may be a device for heat treatment of a magnet well known to those skilled in the art, and the present invention is preferably a vacuum sintering furnace.
  • the present invention further completes and optimizes the process flow. After the above steps, it may further include a post-processing step. Steps such as cleaning, slicing, etc. are not particularly limited, and those skilled in the art may adjust or select according to actual production conditions, product requirements, and the like. .
  • the present invention provides a neodymium iron boron magnet obtained by preparing a neodymium iron boron raw material powder coated with a modified powder comprising a heavy rare earth oxide and/or a heavy rare earth fluoride.
  • the invention also provides a preparation method of a neodymium iron boron magnet, comprising the following steps, firstly, the crushed neodymium iron boron raw material After the powder and the modified powder are mixed at a high speed, a modified NdFeB raw material powder is obtained; the modified powder includes a heavy rare earth oxide powder and/or a heavy rare earth fluoride powder; and then the modified NdFeB obtained by the above step is obtained.
  • a neodymium iron boron magnet is obtained.
  • the invention is creatively started from the aspect of the magnet powder, in particular, the heavy rare earth fluoride or oxide is coated on the surface of the magnetic powder particles, so that the diffusion can be simultaneously performed during the subsequent sintering of the magnet, and The powder of heavy rare earth oxide or fluoride coated on the surface of the magnetic powder particles replaces part of the light rare earth during the sintering process, and the heavy rare earth is absorbed by the magnet, thereby increasing the coercive force and effectively suppressing the decrease of the residual magnetism.
  • the nano-sized heavy rare earth oxide or fluoride is used as a diffusion source to coat the surface of the magnetic powder particles before sintering, and it is further preferred that the diameters of the magnetic powder particles (D) and the modified powder (d) satisfy: 50 ⁇ D / d ⁇ 200, to ensure that the heavy rare earth fluoride or oxide can be effectively coated.
  • the invention completes the particle coating work in the milling step, and performs the penetration in the sintering stage, thereby reducing the coating and diffusion process in the diffusion process, and the diffusion is completed in the sintering stage.
  • the diffusion process of the relatively heavy rare earth oxide or fluoride of the present invention is simpler, and the size of the magnet is not limited.
  • the experimental results show that the NdFeB magnets with modified powders of the present invention have an improvement of coercivity of the magnets by 85%, and the remanence and maximum energy product performance are basically stable.
  • a neodymium iron boron magnet provided by the present invention and a preparation method thereof will be described in detail below with reference to the embodiments, but it should be understood that these embodiments are carried out under the premise of the technical solution of the present invention, and The detailed description of the present invention and the specific operation of the present invention are not intended to limit the scope of the present invention, and the scope of the present invention is not limited to the embodiments described below.
  • the mass ratio of alloy composition is PrNd30-Dy0.3-Al0.4-Cu0.1-B0.95-Fe (balance), and the alloy is broken into 3 micrometers by hydrogen crushing and air milling.
  • high temperature heat treatment was carried out for 8 h, followed by low temperature tempering secondary heat treatment for 5.5 h at a temperature of 510 ° C to obtain a neodymium iron boron magnet.
  • Table 1 shows the magnetic property data of the neodymium iron boron magnet prepared in Comparative Example 1 of the present invention and the neodymium iron boron magnet prepared in Examples 1 to 3.
  • Table 2 shows the high temperature (150 ° C) magnetic property data of the neodymium iron boron magnet prepared in Comparative Example 1 of the present invention and the neodymium iron boron magnet prepared in Examples 1 to 3.
  • the fine powder of the 100% TbF 3 powder and the NdFeB raw material powder (the ratio is the same as Comparative Example 1) was added to a high-speed mixer at a ratio of 2:98, and stirred at a high speed.
  • the stirred mixture is pressed into a square green body (semi-finished product), and then the semi-finished product is placed in a sintered graphite box, and the graphite box in which the product is placed is placed in a sintering furnace, and vacuumed to below 10 -2 Pa at 1050 ° C.
  • the temperature was subjected to high-temperature heat treatment for 8 hours, and then subjected to a low-temperature tempering secondary heat treatment for 5.5 hours at a temperature of 510 ° C to obtain a neodymium-iron-boron magnet.
  • Example 1 of the present invention The neodymium iron boron magnet obtained in Example 1 of the present invention was subjected to normal temperature magnetic property detection, and the specific results are shown in Table 1.
  • Table 1 shows the magnetic property data of the neodymium iron boron magnet prepared in Comparative Example 1 of the present invention and the neodymium iron boron magnet prepared in Examples 1 to 3.
  • Example 1 of the present invention The high temperature magnetic properties of the neodymium iron boron magnet obtained in Example 1 of the present invention were examined. The specific results are shown in Table 2.
  • Table 2 shows the high temperature (150 ° C) magnetic property data of the neodymium iron boron magnet prepared in Comparative Example 1 of the present invention and the neodymium iron boron magnet prepared in Examples 1 to 3.
  • the fine powder of the 100% TbF 3 powder and the NdFeB raw material powder (the ratio is the same as Comparative Example 1) was added to a high-speed mixer at a ratio of 2:98, and stirred at a high speed.
  • the stirred mixture is pressed into a square green body (semi-finished product), and then the semi-finished product is placed in a sintered graphite box, and the graphite box in which the product is placed is placed in a sintering furnace, and vacuumed to below 10 -2 Pa at 1050 ° C.
  • the temperature was subjected to high-temperature heat treatment for 8 hours, and then subjected to a low-temperature tempering secondary heat treatment for 5.5 hours at a temperature of 510 ° C to obtain a neodymium-iron-boron magnet.
  • Example 2 of the present invention The neodymium iron boron magnet obtained in Example 2 of the present invention was subjected to normal temperature magnetic property detection, and the specific results are shown in Table 1.
  • Table 1 shows the magnetic property data of the neodymium iron boron magnet prepared in Comparative Example 1 of the present invention and the neodymium iron boron magnet prepared in Examples 1 to 3.
  • Example 2 of the present invention The high temperature magnetic properties of the neodymium iron boron magnet obtained in Example 2 of the present invention were examined. The specific results are shown in Table 2.
  • Table 2 shows the high temperature (150 ° C) magnetic property data of the neodymium iron boron magnet prepared in Comparative Example 1 of the present invention and the neodymium iron boron magnet prepared in Examples 1 to 3.
  • the fine powder of the 100% TbF 3 powder and the NdFeB raw material powder (the ratio is the same as Comparative Example 1) was added to a high-speed mixer at a ratio of 3:97, and stirred at a high speed.
  • the stirred mixture is pressed into a square green body (semi-finished product), and then the semi-finished product is placed in a sintered graphite box, and the graphite box in which the product is placed is placed in a sintering furnace, and vacuumed to below 10 -2 Pa at 1050 ° C.
  • the temperature was subjected to high-temperature heat treatment for 8 hours, and then subjected to a low-temperature tempering secondary heat treatment for 5.5 hours at a temperature of 510 ° C to obtain a neodymium-iron-boron magnet.
  • Example 3 of the present invention The neodymium iron boron magnet obtained in Example 3 of the present invention was subjected to normal temperature magnetic property detection, and the specific results are shown in Table 1.
  • Table 1 shows the magnetic property data of the neodymium iron boron magnet prepared in Comparative Example 1 of the present invention and the neodymium iron boron magnet prepared in Examples 1 to 3.
  • Example 3 of the present invention The high temperature magnetic properties of the neodymium iron boron magnet obtained in Example 3 of the present invention were examined. The specific results are shown in Table 2.
  • Table 2 shows the neodymium iron boron magnets prepared in Comparative Example 1 of the present invention and the neodymium iron boron magnets prepared in Examples 1 to 3 High temperature (150 ° C) magnetic performance data.

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Abstract

本发明提供了一种钕铁硼磁体，由包覆有改性粉末的钕铁硼原料粉末经制备后得到；所述改性粉末包括重稀土氧化物和/或重稀土氟化物。本发明在磁体制备的诸多步骤中，从磁体粉末方面入手，特别的采用重稀土氟化物或氧化物包覆在磁粉颗粒的表面，这样在磁体后续烧结的过程中能够同时进行扩散，而且包覆在磁粉颗粒表面的重稀土氧化物或氟化物的粉末在烧结的过程中置换了部分轻稀土，重稀土被磁体吸收，从而提高了矫顽力，还能有效抑制了剩磁的下降。本发明采用少量重稀土，就可以提高磁体的矫顽力，节约了重稀土资源，节省了生产成本。同时过程更加简单，磁体的尺寸不受限制。

Description

一种耐高温钕铁硼磁体及其制备方法
本申请要求于2017年08月09日提交中国专利局、申请号为201710675667.5、发明名称为“一种耐高温钕铁硼磁体及其制备方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明属于稀土永磁材料领域，涉及一种钕铁硼磁体及其制备方法，尤其涉及一种耐高温钕铁硼磁体及其制备方法。
背景技术
钕铁硼磁体也称为钕磁体(Neodymium magnet)，其化学式为Nd2Fe14B，是一种人造的永久磁体，也是目前为止具有最强磁力的永久磁体，其最大磁能积(BHmax)高过铁氧体10倍以上，在裸磁的状态下，其磁力可达到3500高斯左右。目前，业界常采用烧结法制作钕铁硼永磁材料，如王伟等在《关键工艺参数和合金元素对烧结NdFeB磁性能与力学性能的影响》中公开了采用烧结法制造钕铁硼永磁材料的工艺流程，一般包括配料、熔炼、钢锭破碎、制粉、氢破碎超细粉、粉末取向压制成型、真空烧结、检分和电镀等步骤。钕铁硼磁体的优点是性价比高，体积小、重量轻、良好的机械特性和磁性强等特点，如此高能量密度的优点使钕铁硼永磁材料在现代工业和电子技术中获得了广泛的应用，在磁学界被誉为磁王。因而，钕铁硼磁体的制备和扩展一直是业内持续关注的焦点。
特别是近些年来，以Nd2Fe14B型化合物为主相的R-Fe-B类稀土烧结磁铁作为永磁体中性能最高的磁体，广泛地用于硬盘驱动的音圈电动机(VCM)、伺服电机、变频空调电机和混合动力车搭载用电动机等，然而在各种电机应用过程中，不仅要求磁体具有高矫顽力的特性，而且为了适应高温的使用环境，要求其耐热性优异。
提高R-Fe-B类稀土烧结磁铁的矫顽力的方法传统方法主要是通过添加重稀土元素RH作为原料，使得R2Fe14B相中的轻稀土元素RL(主要是Nd和Pr)被重稀土元素RH置换，因此，R2Fe14B相的结晶磁各向异性(决定矫顽力的本质的物理量)提高。但是，R2Fe14B相中的轻稀土元素RL的磁矩比重 稀土元素RH的磁矩要高，因此，越是用重稀土元素RH置换轻稀土元素RL，越会导致剩余磁通密度Br下降。另一方面，由于重稀土元素RH是稀少资源，所以希望减少其使用量是非常必要的。
近几年来，渗镝技术也受到了业内的广泛关注，即在磁体表面通过涂覆、沉积、镀覆、溅射或粘覆等方式，涂覆上重稀土元素，再进行渗透；或通过蒸发重稀土后，再在磁体表面镀上一层重稀土金属，然后进行渗透。渗镝技术使含有Dy的金属或化合物的粉末先附着在磁体外表面作为扩散源，再在某一温度范围内进行扩散热处理，使稀土元素沿晶界扩散到主相晶粒表层，从而达到提高晶粒表面各向异性场，改善晶界显微组织，提高磁体矫顽力的工艺。但是渗镝技术在高温热处理的扩散过程中扩散厚度小，对于磁体的性能改变有限。
因此，如何制备得到一种具有较好的高温矫顽力，同时具有较均衡的磁性能的耐高温钕铁硼磁体，已成为钕铁硼磁体生产厂商和领域内一线研究人员广泛关注的焦点之一。
发明内容
有鉴于此，本发明要解决的技术问题在于提供一种钕铁硼磁体及其制备方法，特别是一种耐高温的钕铁硼磁体，本发明提供的钕铁硼磁体具有较好的高温矫顽力，而且磁性能均衡，同时制备方法简单易行，适于大规模工业化生产。
本发明提供了一种钕铁硼磁体，由包覆有改性粉末的钕铁硼原料粉末经制备后得到；
所述改性粉末包括重稀土氧化物粉末和/或重稀土氟化物粉末。
优选的，所述钕铁硼原料粉末的平均粒径与所述改性粉末的平均粒径的比值为(50～200)：1。
优选的，所述重稀土元素包括镝和/或铽。
优选的，所述改性粉末占所述钕铁硼磁体总质量的比例为小于等于4％。
优选的，所述钕铁硼原料粉末中各成分按质量百分比组成，包括：Pr-Nd：28％～33％；Dy：0～10％；Tb：0～10％；Nb：0～5％；B：0.5％～2.0％；Al：0～3.0％；Cu：0～1％；Co：0～3％；Ga：0～2％；Gd：0～2％；Ho：0～2％；Zr：0～2％；余量为Fe。
优选的，所述钕铁硼原料粉末包括，仅采用钕铁硼原料粉末制备的成品磁 体的内禀矫顽力大于等于17kOe的中高矫顽力的磁体原料粉末。
本发明还提供了一种钕铁硼磁体的制备方法，包括以下步骤：
A)将破碎后的钕铁硼原料粉末与改性粉末经过高速混合后，得到改性钕铁硼原料粉末；
所述改性粉末包括重稀土氧化物粉末和/或重稀土氟化物粉末；
B)将上述步骤得到的改性钕铁硼原料粉末进行压制和烧结后，得到钕铁硼磁体。
优选的，所述高速混合的时间为0.1～2小时；
所述高速混合的转速为80～220rpm。
优选的，所述烧结的温度为1030～1090℃；
所述烧结的时间为3～10小时；
所述烧结后还包括时效处理步骤。
优选的，所述时效处理具体包括一级退火时效处理和二级退火时效处理；
所述一级退火时效处理的温度为800～950℃；所述一级退火时效处理的时间为3～10小时；
所述二级退火时效处理的温度为400～550℃；所述二级退火时效处理的时间为3～10小时。
本发明提供了一种钕铁硼磁体，由包覆有改性粉末的钕铁硼原料粉末经制备后得到；所述改性粉末包括重稀土氧化物和/或重稀土氟化物。与现有技术相比，本发明针对现有的重稀土元素置换轻稀土元素，导致剩余磁通密度Br下降，用量大的缺陷，而渗镝技术也存在扩散厚度小，对于磁体的性能改变有限的问题。本发明在磁体制备的诸多步骤中，创造性的从磁体粉末方面入手，特别的采用重稀土氟化物或氧化物包覆在磁粉颗粒的表面，这样在磁体后续烧结的过程中能够同时进行扩散，而且包覆在磁粉颗粒表面的重稀土氧化物或氟化物的粉末在烧结的过程中置换了部分轻稀土，重稀土被磁体吸收，从而提高了矫顽力，还能有效抑制了剩磁的下降。本发明采用重稀土氧化物或氟化物作为扩散源在烧结前就包覆在磁粉颗粒的表面，采用少量的重稀土材料，就能够显著的提高了磁体矫顽力的基础上，节约了重稀土资源，节省了生产成本。同时本发明相对现有的扩散渗镝工艺，过程更加简单，磁体的尺寸不受限制。
实验结果表明，本发明加入改性粉末的钕铁硼磁体比相同牌号的钕铁硼磁体在磁体矫顽力性能方面提高达到了85％，而剩磁和最大磁能积性能方面基本保持稳定。
具体实施方式
为了进一步理解本发明，下面结合实施例对本发明优选实施方案进行描述，但是应当理解，这些描述只是为了进一步说明本发明的特征和优点，而不是对发明权利要求的限制。
本发明所有原料，对其来源没有特别限制，在市场上购买的或按照本领域技术人员熟知的常规方法制备的即可。
本发明所有原料，对其纯度没有特别限制，本发明优选采用分析纯或钕铁硼磁体领域使用的常规纯度。
本发明提供了一种钕铁硼磁体，由包覆有改性粉末的钕铁硼原料粉末经制备后得到；
所述改性粉末包括重稀土氧化物粉末和/或重稀土氟化物粉末。
本发明对所述重稀土元素没有特别限制，以本领域技术人员熟知的用于磁体材料的重稀土元素即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述重稀土元素优选包括镝和/或铽，更优选为镝或铽。
本发明对所述重稀土氧化物没有特别限制，以本领域技术人员熟知的用于磁体材料的重稀土氧化物即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述重稀土氧化物优选包括Dy2O3、Tb2O3或Tb4O7，更优选为Dy2O3或Tb2O3。
本发明对所述重稀土氟化物没有特别限制，以本领域技术人员熟知的用于磁体材料的重稀土氟化物即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述重稀土氟化物优选包括DyF3或TbF3。
本发明对所述改性粉末的加入量没有特别限制，以本领域技术人员熟知的用于磁体材料的此类材料的加入量即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，所述改性粉末占所述钕铁硼磁体 总质量的比例优选为小于等于4％，更优选为0.01％～4％，更优选为0.1％～3.5％，，更优选为1％～3％，更优选为1.5％～2.5％。
本发明对所述改性粉末的粒径没有特别限制，以本领域技术人员熟知的用于磁体材料的常规粒径即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述改性粉末优选为纳米级改性粉末，具体粒径更优选为10～300nm，更优选为20～250nm，更优选为30～200nm，更优选为50～150nm，更优选为60～100nm。
本发明对所述钕铁硼原料粉末的平均粒径与改性粉末的平均粒径比没有特别限制，以本领域技术人员熟知的用于磁体材料的常规粒径比即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明为提高包覆效果，进而保证产品磁性能，所述钕铁硼原料粉末的平均粒径与所述改性粉末的平均粒径的比值优选为(50～200)：1，更优选为(75～175)：1，最优选为(100～150)：1。
本发明对所述平均粒径的定义没有特别限制，以本领域技术人员熟知的用于磁体材料的常规平均粒径定义即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述平均粒径优选是指面积平均粒径(SMD)。
本发明对所述钕铁硼原料粉末的组成没有特别限制，以本领域技术人员熟知的钕铁硼原料粉末的组成即可，本领域技术人员可以根据实际应用情况、产品要求以及质量要求等因素进行选择和调整，本发明所述钕铁硼原料粉末中各成分按质量百分比组成，优选包括：Pr-Nd：28％～33％、Dy：0～10％、Tb：0～10％、Nb：0～5％、B：0.5％～2.0％、Al：0～3.0％、Cu：0～1％、Co：0～3％、Ga：0～2％、Gd：0～2％、Ho：0～2％、Zr：0～2％和余量的Fe，更优选包括Pr-Nd：28.40％～33.00％、Dy：0.50％～6.0％、Tb：0.50％～6.0％、B：0.92％～0.98％、Al：0.10％～3.0％、Cu：0.10％～0.25％、Co：0.10％～3.0％，Ga：0.1％～0.3％和余量的Fe。
本发明对所述钕铁硼磁体原料的具体牌号没有特别限制，以本领域技术人员熟知的钕铁硼磁体的常规牌号即可，本领域技术人员可以根据实际应用情况、产品要求以及质量要求等因素进行选择和调整，本发明所述钕铁硼原料粉 末包括，仅采用钕铁硼原料粉末制备的成品磁体的内禀矫顽力大于等于17kOe的中高矫顽力的磁体原料粉末，即加入改性粉末前的纯钕铁硼原料粉末制备的普通磁体，优选为其内禀矫顽力大于等于17kOe的中高矫顽力的磁体，可以包括(中等矫顽力)M类钕铁硼磁体、(高矫顽力)H类钕铁硼磁体、(特高矫顽力)SH类钕铁硼磁体、(超高矫顽力)UH类钕铁硼磁体或者(极高矫顽力)、EH类钕铁硼磁体或AH类钕铁硼磁体的原料，本发明优选采用H类钕铁硼磁体原料、SH类钕铁硼磁体原料或UH钕铁硼磁体原料，更优选为SH类钕铁硼磁体原料，具体的，可采用42SH、45SH或40UH牌号的钕铁硼磁体，具体优选为42SH。
本发明还提供了一种钕铁硼磁体的制备方法，包括以下步骤：
A)将破碎后的钕铁硼原料粉末与改性粉末经过高速混合后，得到改性钕铁硼原料粉末；
所述改性粉末包括重稀土氧化物粉末和/或重稀土氟化物粉末；
B)将上述步骤得到的改性钕铁硼原料粉末进行压制和烧结后，得到钕铁硼磁体。
本发明上述制备方法中，关于原料、比例以及其他参数的选择和优选原则与前述钕铁硼磁体中的原料、比例以及其他参数的选择和优选原则均一致，在此不再一一赘述。
本发明首先将破碎后的钕铁硼原料粉末与改性粉末经过高速混合后，得到改性钕铁硼原料粉末。
本发明对所述破碎后的钕铁硼原料粉末没有特别限制，以本领域技术人员熟知的常规钕铁硼磁体制备过程中的钕铁硼原料粉末即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述破碎后的钕铁硼原料粉末优选是指，钕铁硼原料经过配料、熔炼、破碎、制粉和氢碎等一步或多步之后的钕铁硼原料细粉。
本发明对所述钕铁硼原料粉末的粒径没有特别限制，以本领域技术人员熟知的用于磁体制备的常规粒径即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述钕铁硼原料粉末的平均粒径优选为1.0～5.0μm，更优选为1.5～4.5μm，更优选为2.0～3.0μm。
本发明对所述高速混合的时间没有特别限制，以本领域技术人员熟知的常规混合时间即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述高速混合的时间优选为0.1～2小时，更优选为0.5～1.5小时，更优选为5～60分钟，更优选为20～45分钟。
本发明对所述高速混合的转速没有特别限制，以本领域技术人员熟知的常规混合转速即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述高速混合的转速优选为80～220rpm，更优选为100～200rpm，更优选为120～180rpm。
本发明对所述改性钕铁硼原料粉末的粒径没有特别限制，以本领域技术人员熟知的用于磁体制备的常规粒径即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述改性钕铁硼原料粉末的平均粒径优选为1.0～5.0μm，更优选为1.5～4.5μm，更优选为2.0～3.0μm。
本发明最后将上述步骤得到的改性钕铁硼原料粉末进行压制和烧结后，得到钕铁硼磁体。
本发明对所述压制方式没有特别限制，以本领域技术人员熟知的钕铁硼原料粉末的压制方式即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述压制优选包括取向压制和等静压成型，更优选为在氮气或惰性气体保护下进行取向压制，再进行油等静压成型。
本发明对所述烧结的时间没有特别限制，以本领域技术人员熟知的钕铁硼磁体的烧结时间即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述烧结的时间优选为3～10小时，更优选为4～9小时，更优选为5～8小时，最优选为6～7小时。
本发明对所述烧结的温度没有特别限制，以本领域技术人员熟知的钕铁硼磁体的烧结温度即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述烧结的温度优选为1030～1090℃，更优选为1040～1080℃，最优选为1050～1070℃。
本发明为提高产品的磁性能，完整和优化工艺流程，所述烧结后优选还包括时效处理步骤。
本发明对所述时效处理的具体过程和步骤没有特别限制，以本领域技术人 员熟知的类似热处理的工艺即可，本发明所述时效处理具体优选包括一级退火时效处理和二级退火时效处理。
本发明对所述一级退火时效处理的具体温度没有特别限制，以本领域技术人员熟知的时效处理温度即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述一级退火时效处理的温度优选为800～950℃，更优选为825～925℃，最优选为850～900℃。
本发明对所述一级退火时效处理的具体时间没有特别限制，以本领域技术人员熟知的时效处理时间即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述一级退火时效处理的时间优选为3～10小时，更优选为4～9小时，更优选为5～8小时，最优选为6～7小时。
本发明对所述二级退火时效处理的具体温度没有特别限制，以本领域技术人员熟知的时效处理温度即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述二级退火时效处理的温度优选为400～550℃，更优选为425～525℃，最优选为450～500℃。
本发明对所述二级退火时效处理的具体时间没有特别限制，以本领域技术人员熟知的时效处理时间即可，本领域技术人员可以根据实际生产情况、产品要求以及质量要求进行选择和调整，本发明所述二级退火时效处理的时间优选为3～10小时，更优选为4～9小时，更优选为5～8小时，最优选为6～7小时。
本发明对所述烧结和时效处理的其他条件没有特别限制，以本领域技术人员熟知的磁体烧结和时效处理的条件即可，本发明为提高热处理工艺的效果，还优选在在保护气氛或真空下进行烧结和时效处理。本发明对所述烧结和时效处理的设备没有特别限制，以本领域技术人员熟知的磁体热处理的设备即可，本发明优选为真空烧结炉。
本发明为进一步完整和优化工艺流程，在上述步骤之后，可能还包括后处理步骤，如清洗、切片等步骤不做特别限制，本领域技术人员可以根据实际生产情况、产品要求等进行调整或选择。
本发明提供了一种钕铁硼磁体，由包覆有改性粉末的钕铁硼原料粉末经制备后得到；所述改性粉末包括重稀土氧化物和/或重稀土氟化物。本发明还提供了一种钕铁硼磁体的制备方法，包括以下步骤，首先将破碎后的钕铁硼原料 粉末与改性粉末经过高速混合后，得到改性钕铁硼原料粉末；所述改性粉末包括重稀土氧化物粉末和/或重稀土氟化物粉末；然后将上述步骤得到的改性钕铁硼原料粉末进行压制和烧结后，得到钕铁硼磁体。本发明在磁体制备的诸多步骤中，创造性的从磁体粉末方面入手，特别的采用重稀土氟化物或氧化物包覆在磁粉颗粒的表面，这样在磁体后续烧结的过程中能够同时进行扩散，而且包覆在磁粉颗粒表面的重稀土氧化物或氟化物的粉末在烧结的过程中置换了部分轻稀土，重稀土被磁体吸收，从而提高了矫顽力，还能有效抑制了剩磁的下降。
本发明进一步优选采用纳米级重稀土氧化物或氟化物作为扩散源在烧结前就包覆在磁粉颗粒的表面，更进一步优选磁粉颗粒(D)和改性粉末(d)的直径满足：50≤D/d≤200，确保重稀土氟化物或氧化物能进行有效包覆。本发明在制粉环节完成颗粒包覆工作，在烧结阶段进行渗透，减少了扩散过程中的涂覆和扩散过程，扩散在烧结阶段即完成。然后在烧结的过程中置换部分轻稀土，采用少量的重稀土就能够显著的提高磁体的矫顽力，节约了重稀土资源，节省了生产成本。同时本发明相对重稀土氧化物或氟化物的扩散工艺，过程更加简单，磁体的尺寸不受限制。
实验结果表明，本发明加入改性粉末的钕铁硼磁体比相同牌号的钕铁硼磁体在磁体矫顽力性能方面提高达到了85％，而剩磁和最大磁能积性能方面基本保持稳定。
为了进一步说明本发明，以下结合实施例对本发明提供的一种钕铁硼磁体及其制备方法进行详细描述，但是应当理解，这些实施例是在以本发明技术方案为前提下进行实施，给出了详细的实施方式和具体的操作过程，只是为进一步说明本发明的特征和优点，而不是对本发明权利要求的限制，本发明的保护范围也不限于下述的实施例。
比较例1
熔炼42SH的合金，合金成分质量比为PrNd30-Dy0.3-Al0.4-Cu0.1-B0.95-Fe(余量)，将合金通过氢破碎、气流磨制粉的方法破碎成3微米左右的细粉，然后将此细粉制成方形生坯(半成品)，再将 半成品放置于烧结石墨盒中，将放有产品的石墨盒放入烧结炉中，抽真空至10-2Pa以下，在1050℃的温度下，进行高温热处理8h，接着在510℃的温度下，进行低温回火二级热处理5.5h后，得到钕铁硼磁体。
对本发明比较例1得到的钕铁硼磁体进行常温磁性能检测，具体结果参见表1。表1为本发明比较例1制备的钕铁硼磁体和实施例1～3制备的钕铁硼磁体的磁性能数据。
对本发明比较例1得到的钕铁硼磁体进行高温磁性能检测，具体结果参见表2。表2为本发明比较例1制备的钕铁硼磁体和实施例1～3制备的钕铁硼磁体的高温(150℃)磁性能数据。
实施例1
将100％TbF3的粉末和钕铁硼原料粉末(比例同比较例1)气流磨后的细粉按照2:98的比例加入高速搅拌机中，并进行高速搅拌。
然后将搅拌好的混合物压制成方形生坯(半成品)，再将半成品放置于烧结石墨盒中，将放有产品的石墨盒放入烧结炉中，抽真空至10-2Pa以下，在1050℃的温度下，进行高温热处理8h，接着在510℃的温度下，进行低温回火二级热处理5.5h后，得到钕铁硼磁体。
对本发明实施例1得到的钕铁硼磁体进行常温磁性能检测，具体结果参见表1。表1为本发明比较例1制备的钕铁硼磁体和实施例1～3制备的钕铁硼磁体的磁性能数据。
对本发明实施例1得到的钕铁硼磁体进行高温磁性能检测，具体结果参见表2。表2为本发明比较例1制备的钕铁硼磁体和实施例1～3制备的钕铁硼磁体的高温(150℃)磁性能数据。
实施例2
将100％TbF3的粉末和钕铁硼原料粉末(比例同比较例1)气流磨后的细粉按照2:98的比例加入高速搅拌机中，并进行高速搅拌。
然后将搅拌好的混合物压制成方形生坯(半成品)，再将半成品放置于烧结石墨盒中，将放有产品的石墨盒放入烧结炉中，抽真空至10-2Pa以下，在1050℃的温度下，进行高温热处理8h，接着在510℃的温度下，进行低温回火二级热处理5.5h后，得到钕铁硼磁体。
对本发明实施例2得到的钕铁硼磁体进行常温磁性能检测，具体结果参见表1。表1为本发明比较例1制备的钕铁硼磁体和实施例1～3制备的钕铁硼磁体的磁性能数据。
对本发明实施例2得到的钕铁硼磁体进行高温磁性能检测，具体结果参见表2。表2为本发明比较例1制备的钕铁硼磁体和实施例1～3制备的钕铁硼磁体的高温(150℃)磁性能数据。
实施例3
将100％TbF3的粉末和钕铁硼原料粉末(比例同比较例1)气流磨后的细粉按照3:97的比例加入高速搅拌机中，并进行高速搅拌。
然后将搅拌好的混合物压制成方形生坯(半成品)，再将半成品放置于烧结石墨盒中，将放有产品的石墨盒放入烧结炉中，抽真空至10-2Pa以下，在1050℃的温度下，进行高温热处理8h，接着在510℃的温度下，进行低温回火二级热处理5.5h后，得到钕铁硼磁体。
对本发明实施例3得到的钕铁硼磁体进行常温磁性能检测，具体结果参见表1。表1为本发明比较例1制备的钕铁硼磁体和实施例1～3制备的钕铁硼磁体的磁性能数据。
表1 本发明实施例1～3和比较例1得到的钕铁硼磁体性能数据
  改性粉：钕铁硼粉 Br(kGs) Hcj(kOe) (BH)max(MGOe)
比较例1 0 13.21 19.55 42.06
实施例1 1:99 13.15 26.87 41.98
实施例2 2:98 13.10 30.18 41.92
实施例3 3:97 13.10 36.15 41.86
由表1可以看出，42SH熔炼时加入了重稀土的钕铁硼磁体，其矫顽力只有19.55，而本申请实施例2～4中的改性钕铁硼磁体的矫顽力均有明显的提高，且剩磁和磁能积基本没有下降。
对本发明实施例3得到的钕铁硼磁体进行高温磁性能检测，具体结果参见表2。表2为本发明比较例1制备的钕铁硼磁体和实施例1～3制备的钕铁硼磁 体的高温(150℃)磁性能数据。
表2
  改性粉：钕铁硼粉 Br(kGs) Hcj(kOe) (BH)max(MGOe)
比较例1 0 11.22 6.15 29.83
实施例1 1:99 11.26 10.77 30.19
实施例2 2:98 11.29 13.35 30.49
实施例3 3:97 11.35 17.02 30.78
由表2可以看出，42SH熔炼时加入了重稀土的钕铁硼磁体，但在150℃高温下，其矫顽力仅剩6.15，而本申请实施例2～4中的改性钕铁硼磁体在150℃高温下的矫顽力、剩磁和磁能积均有明显的优异的表现。
以上对本发明提供的一种耐高温钕铁硼磁体及其制备方法进行了详细的介绍，本文中应用了具体个例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想，包括最佳方式，并且也使得本领域的任何技术人员都能够实践本发明，包括制造和使用任何装置或系统，和实施任何结合的方法。应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以对本发明进行若干改进和修饰，这些改进和修饰也落入本发明权利要求的保护范围内。本发明专利保护的范围通过权利要求来限定，并可包括本领域技术人员能够想到的其他实施例。如果这些其他实施例具有不是不同于权利要求文字表述的结构要素，或者如果它们包括与权利要求的文字表述无实质差异的等同结构要素，那么这些其他实施例也应包含在权利要求的范围内。

Claims (10)

  1. 一种钕铁硼磁体，其特征在于，由包覆有改性粉末的钕铁硼原料粉末经制备后得到；
    所述改性粉末包括重稀土氧化物粉末和/或重稀土氟化物粉末。
  2. 根据权利要求1所述的钕铁硼磁体，其特征在于，所述钕铁硼原料粉末的平均粒径与所述改性粉末的平均粒径的比值为(50～200)：1。
  3. 根据权利要求1所述的钕铁硼磁体，其特征在于，所述重稀土元素包括镝和/或铽。
  4. 根据权利要求1所述的钕铁硼磁体，其特征在于，所述改性粉末占所述钕铁硼磁体总质量的比例为小于等于4％。
  5. 根据权利要求1所述的钕铁硼磁体，其特征在于，所述钕铁硼原料粉末中各成分按质量百分比组成，包括：Pr-Nd：28％～33％；Dy：0～10％；Tb：0～10％；Nb：0～5％；B：0.5％～2.0％；Al：0～3.0％；Cu：0～1％；Co：0～3％；Ga：0～2％；Gd：0～2％；Ho：0～2％；Zr：0～2％；余量为Fe。
  6. 根据权利要求1所述的钕铁硼磁体，其特征在于，所述钕铁硼原料粉末包括，仅采用钕铁硼原料粉末制备的成品磁体的内禀矫顽力大于等于17kOe的中高矫顽力的磁体原料粉末。
  7. 一种钕铁硼磁体的制备方法，其特征在于，包括以下步骤：
    A)将破碎后的钕铁硼原料粉末与改性粉末经过高速混合后，得到改性钕铁硼原料粉末；
    所述改性粉末包括重稀土氧化物粉末和/或重稀土氟化物粉末；
    B)将上述步骤得到的改性钕铁硼原料粉末进行压制和烧结后，得到钕铁硼磁体。
  8. 根据权利要求7所述的制备方法，其特征在于，所述高速混合的时间为0.1～2小时；
    所述高速混合的转速为80～220rpm。
  9. 根据权利要求7所述的制备方法，其特征在于，所述烧结的温度为1030～1090℃；
    所述烧结的时间为3～10小时；
    所述烧结后还包括时效处理步骤。
  10. 根据权利要求7所述的制备方法，其特征在于，所述时效处理具体包括一级退火时效处理和二级退火时效处理；
    所述一级退火时效处理的温度为800～950℃；所述一级退火时效处理的时间为3～10小时；
    所述二级退火时效处理的温度为400～550℃；所述二级退火时效处理的时间为3～10小时。
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