阅读说明：本技术 一种复合稀土类异方性粘结磁体及其制备方法 (Composite rare earth anisotropic bonded magnet and preparation method thereof ) 是由 罗阳 王子龙 杨远飞 于敦波 廖一帆 谢佳君 王仲凯 胡州 于 2019-11-06 设计创作，主要内容包括：一种复合稀土类异方性粘结磁体及其制备方法,该复合稀土类异方性粘结磁体包括Nd-Fe-B系磁粉、Sm-Fe-N系磁粉、粘结剂以及无机纳米分散剂；该制备方法包括用HDDR法制备Nd-Fe-B系磁粉,用粉末冶金法制备Sm-Fe-N系磁粉,将Nd-Fe-B系磁粉、Sm-Fe-N系磁粉、粘结剂和无机纳米分散剂按特定比例混合,最终制成复合稀土类异方性粘结磁体。本发明通过加入无机纳米分散剂,使得在粘结剂与Nd-Fe-B系磁粉和Sm-Fe-N磁粉混合过程中,可以对细微Sm-Fe-N粉末进行充分的分散,使细微Sm-Fe-N粉末和粘结剂均匀地包覆在异方性Nd-Fe-B系磁粉表面,能够进一步提升复合磁体的综合磁性能、密度及组织均匀性。(A composite rare earth anisotropic bonded magnet and a preparation method thereof, the composite rare earth anisotropic bonded magnet comprises Nd-Fe-B series magnetic powder, Sm-Fe-N series magnetic powder, a binder and an inorganic nano dispersant; the preparation method comprises the steps of preparing Nd-Fe-B series magnetic powder by an HDDR method, preparing Sm-Fe-N series magnetic powder by a powder metallurgy method, mixing the Nd-Fe-B series magnetic powder, the Sm-Fe-N series magnetic powder, a binder and an inorganic nano dispersant according to a specific proportion, and finally preparing the composite rare earth anisotropic bonded magnet. According to the invention, by adding the inorganic nano dispersing agent, the fine Sm-Fe-N powder can be fully dispersed in the mixing process of the binder, the Nd-Fe-B system magnetic powder and the Sm-Fe-N magnetic powder, so that the fine Sm-Fe-N powder and the binder are uniformly coated on the surface of the anisotropic Nd-Fe-B system magnetic powder, and the comprehensive magnetic performance, density and tissue uniformity of the composite magnet can be further improved.)

1. A composite rare earth anisotropic bonded magnet characterized in that: comprises Nd-Fe-B series magnetic powder, Sm-Fe-N series magnetic powder, a binder and an inorganic nano dispersant;

wherein, the content of Sm-Fe-N series magnetic powder is 5 to 30 wt.%, the content of binder is 1 to 10 wt.%, the content of inorganic nano dispersant is 0.1 to 2 wt.%, and the rest is Nd-Fe-B series magnetic powder.

2. The composite rare earth anisotropic bonded magnet according to claim 1, wherein:

the inorganic nano dispersant is Al ₂O ₃、SiO ₂Or TiO ₂Any one or more of them, the particle size is 30-100 nm.

3. The composite rare earth anisotropic bonded magnet according to claim 2, wherein a circularity of the Nd-Fe-B magnetic powder is 0.6 to 0.8.

4. The composite rare earth anisotropic bonded magnet according to claim 3, wherein the average grain size of the Sm-Fe-N magnetic powder is 1 to 12 μm.

5. The composite rare earth anisotropic bonded magnet according to claim 4, wherein a squareness of the anisotropic bonded magnet is more than 30%.

6. The composite rare earth anisotropic bonded magnet according to claim 5, wherein:

the surface of the Sm-Fe-N series magnetic powder is coated with an F-containing organic matter.

7. The composite rare earth anisotropic bonded magnet according to claim 6, wherein:

the F-containing organic matter is fluorine-containing alkane or fluorine-containing olefin.

8. The method for producing a composite rare-earth anisotropic bonded magnet according to any one of claims 1 to 7, comprising the steps of:

preparing Nd-Fe-B series magnetic powder by an HDDR method;

preparing Sm-Fe-N series magnetic powder by a powder metallurgy method;

mixing the Nd-Fe-B series magnetic powder, the Sm-Fe-N series magnetic powder, a binder and an inorganic nano dispersant according to a specific proportion to prepare mixed rubber powder;

and (3) preparing the mixed rubber powder into the composite rare earth anisotropic bonded magnet through mould pressing, injection, calendering or extrusion.

9. The method of claim 8, wherein the step of mixing the Nd-Fe-B system magnetic powder, the Sm-Fe-N system magnetic powder, the binder and the inorganic nano-dispersant in a specific ratio to produce a mixed powder comprises:

dissolving the binder with an organic solvent to prepare a first organic solution;

adding an inorganic nano dispersant into the first organic solution to prepare a second organic solution;

adding the Sm-Fe-N magnetic powder into the second organic solution, and uniformly dispersing by using ultrasonic waves to prepare a third organic solution;

and adding the Nd-Fe-B series magnetic powder into the third organic solution, and fully stirring to completely volatilize the organic solvent in the third organic solution to prepare mixed rubber powder.

10. The method according to claim 9, wherein the step of producing the Sm — Fe — N system magnetic powder further comprises:

coating an organic matter containing F on the surface of the Sm-Fe-N series magnetic powder:

adding the Sm-Fe-N magnetic powder into an organic solution containing F organic matters, and fully stirring to prepare a fully stirred organic solution;

and completely volatilizing the organic solvent in the fully stirred organic solution to ensure that the F-containing organic matter is coated on the surface of the Sm-Fe-N magnetic powder.

Technical Field

The invention relates to the technical field of magnetic materials, in particular to a composite rare earth anisotropic bonded magnet and a preparation method thereof.

Background

The magnetic powder for bonding the neodymium iron boron permanent magnet material is mainly divided into two main categories of isotropy and anisotropy. The isotropic neodymium iron boron magnetic powder is prepared by a melt rapid quenching method at present, the maximum magnetic energy product is 12-16MGOe, and the maximum magnetic energy product of the prepared isotropic neodymium iron boron bonded magnet is not more than 12 MGOe; the anisotropic neodymium iron boron bonded magnetic powder is usually prepared by adopting an HDDR method, due to the particularity of the microstructure, namely that fine grains (200 plus 500nm) are arranged in parallel in the [001] easy magnetization axis direction, the maximum magnetic energy product can reach 2-3 times of that of the isotropic bonded magnetic powder, and a high-performance anisotropic bonded magnet can be prepared by a die pressing or injection molding process, so that the anisotropic bonded magnetic powder conforms to the development trend of miniaturization, light weight and precision of motor devices.

In the magnet molding process, the single grain size range is not favorable for improving the density of the molded magnet. The best mode is that the coarse powder and a certain proportion of fine powder are reasonably proportioned, so that the fine powder can be filled in gaps formed by the coarse powder, and the pressing density of the magnet is improved. The Nd-Fe-B series magnetic powder prepared by the HDDR method is prepared by the processes of hydrogen absorption, disproportionation, dehydrogenation and repolymerization, and the particle size of the magnetic powder is between 50 and 200 microns. Due to the higher activity, the subsequent crushing can cause the oxygen content of the magnetic powder to be greatly increased, the magnetic performance to be reduced, and the preparation of finer powder by crushing is not easy.

By adding anisotropic Sm-Fe-N magnetic powder with finer granularity (1-12 microns), the density of the formed magnet can be effectively improved. Patent document ZL200410085531.1 discloses that a bonded magnet is composed of R1-based d-HDDR coarse magnet powder containing Co at 6 at% or less, whose surface is covered with a surfactant, and R2-based fine magnet powder whose surface is covered with a surfactant, and a resin as a binder, which have a specific average particle diameter and a specific mixing ratio. However, since the particle size of the R2 series fine magnet (Sm-Fe-N) is in the range of 1 to 10 μm, it is easy to agglomerate and disperse, and it is liable to adversely affect the distribution uniformity of the fine magnet powder during the magnet molding process and the overall magnetic properties and density of the pressed magnet. How to overcome the problem of easy agglomeration is not described or described at all.

Disclosure of Invention

In order to solve the problems, the invention provides a composite rare earth anisotropic bonded magnet and a preparation method thereof, wherein an inorganic nano dispersant is added, so that in the mixing process of a binder, Nd-Fe-B system magnetic powder and Sm-Fe-N system magnetic powder, fine Sm-Fe-N powder can be fully dispersed, the fine Sm-Fe-N powder and the binder are uniformly coated on the surface of the anisotropic Nd-Fe-B system magnetic powder, and the comprehensive magnetic performance, density and tissue uniformity of the composite magnet can be further improved.

In order to achieve the above purpose, the present invention adopts the following scheme:

the invention provides a composite rare earth anisotropic bonded magnet, which comprises Nd-Fe-B series magnetic powder, Sm-Fe-N series magnetic powder, a binder and an inorganic nano dispersant;

wherein, the content of Sm-Fe-N series magnetic powder is 5 to 30 wt.%, the content of binder is 1 to 10 wt.%, the content of inorganic nano dispersant is 0.1 to 2 wt.%, and the rest is Nd-Fe-B series magnetic powder.

Further, the inorganic nano dispersant is Al ₂O ₃、SiO ₂Or TiO ₂Any one or more of them, the particle size is 30-100 nm.

Further, the circularity of the Nd-Fe-B magnetic powder is 0.6-0.8.

Further, the average grain size of the Sm-Fe-N series magnetic powder is 1-12 microns.

Further, the squareness of the anisotropic bonded magnet is greater than 30%.

Further, the surface of the Sm-Fe-N series magnetic powder is coated with an F-containing organic matter.

Further, the F-containing organic matter is fluorine-containing alkane or fluorine-containing olefin.

The composite rare earth anisotropic bonded magnet of the present invention is described in detail above.

A second aspect of the present invention provides a method for producing a composite rare earth anisotropic bonded magnet, comprising the steps of:

preparing Nd-Fe-B series magnetic powder by an HDDR method;

preparing Sm-Fe-N series magnetic powder by a powder metallurgy method;

mixing the Nd-Fe-B series magnetic powder, the Sm-Fe-N series magnetic powder, a binder and an inorganic nano dispersant according to a specific proportion to prepare mixed rubber powder;

and (3) preparing the mixed rubber powder into the composite rare earth anisotropic bonded magnet through mould pressing, injection, calendering or extrusion.

Further, the step of mixing the Nd-Fe-B series magnetic powder, the Sm-Fe-N series magnetic powder, the binder and the inorganic nano dispersant according to a specific proportion to prepare mixed rubber powder comprises the following steps:

dissolving the binder with an organic solvent to prepare a first organic solution;

adding an inorganic nano dispersant into the first organic solution to prepare a second organic solution;

adding the Sm-Fe-N magnetic powder into the second organic solution, and uniformly dispersing by using ultrasonic waves to prepare a third organic solution;

and adding the Nd-Fe-B series magnetic powder into the third organic solution, and fully stirring to completely volatilize the organic solvent in the third organic solution to prepare mixed rubber powder.

Further, the step of preparing the Sm-Fe-N magnetic powder further comprises:

coating an organic matter containing F on the surface of the Sm-Fe-N series magnetic powder:

adding the Sm-Fe-N magnetic powder into an organic solution containing F organic matters, and fully stirring to prepare a fully stirred organic solution;

and completely volatilizing the organic solvent in the fully stirred organic solution to ensure that the F-containing organic matter is coated on the surface of the Sm-Fe-N magnetic powder.

The method for producing the composite rare earth anisotropic bonded magnet of the present invention is described in detail above.

In summary, the present invention provides a composite rare earth anisotropic bonded magnet and a method for producing the same, the composite rare earth anisotropic bonded magnet comprising Nd-Fe-B system magnetic powder, Sm-Fe-N system magnetic powder, a binder, and an inorganic nano-dispersant; the preparation method comprises the steps of preparing Nd-Fe-B series magnetic powder by an HDDR method, preparing Nd-Fe-B series magnetic powder by a powder metallurgy method, coating an F-containing organic matter on the surface of Sm-Fe-N series magnetic powder, mixing the Nd-Fe-B series magnetic powder, the Sm-Fe-N series magnetic powder coated with the F-containing organic matter on the surface, a binder and an inorganic nano dispersant according to a specific proportion to prepare mixed rubber powder, and preparing the mixed rubber powder into the composite rare earth anisotropic bonded magnet through mould pressing, injection, calendaring or extrusion.

The technical scheme of the invention has the following beneficial technical effects:

the invention aims to fully disperse the fine powder Sm-Fe-N series magnetic powder by adding the inorganic nano dispersing agent, so that the fine powder Sm-Fe-N series magnetic powder and the binder are uniformly coated on the surface of the anisotropic Nd-Fe-B series magnetic powder, and the comprehensive magnetic performance, density and tissue uniformity of the composite magnet can be further improved.

Drawings

FIG. 1 is a flow chart of a method for manufacturing a composite rare earth anisotropic bonded magnet;

FIG. 2 is a flow chart of a method for manufacturing mixed rubber powder by mixing Nd-Fe-B series magnetic powder, Sm-Fe-N series magnetic powder, a binder and an inorganic nano dispersant according to a specific proportion;

FIG. 3 is a flow chart of a method for coating the surface of Sm-Fe-N magnetic powder with an F-containing organic substance.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

Interpretation of terms:

and (3) calculating the circularity:

the magnetic powder was photographed by SEM (scanning electron microscope) and the photograph was analyzed to calculate the circularity.

The formula for calculating the circularity is:

circularity (4 pi area)/(circumference length)

Therefore, the circularity of the circle is 1; the closer the calculated circularity is to 1, the better its circularity is represented.

In order to achieve the above purpose, the invention adopts the following scheme:

the invention provides a composite rare earth anisotropic bonded magnet, which comprises Nd-Fe-B series magnetic powder, Sm-Fe-N series magnetic powder, a binder and an inorganic nano dispersant; wherein, the content of Sm-Fe-N series magnetic powder is 5 to 30 wt.%, the content of binder is 1 to 10 wt.%, the content of inorganic nano dispersant is 0.1 to 2 wt.%, and the rest is Nd-Fe-B series magnetic powder.

Further, the binder includes a resin; the inorganic nano dispersant is Al ₂O ₃、SiO ₂Or TiO ₂Any one or more of them, the particle size is 30-100 nm; the circularity of the Nd-Fe-B series magnetic powder is 0.6-0.8, the average particle size of the Sm-Fe-N series magnetic powder is 1-12 microns, the squareness of the anisotropic bonded magnet is more than 30%, and the surface of the Sm-Fe-N series magnetic powder is coated with an F-containing organic matter.

Specifically, the F-containing organic matter is fluorine-containing alkane or fluorine-containing olefin.

The circularity of the Nd-Fe-B series magnetic powder is less than 0.6, the fluidity is not good, and the powder is not easy to be pressed to be compact, so that the performance is not high; if the circularity is more than 0.8, the large particles of the magnetic powder have good fluidity and are not easy to be uniformly mixed with the Sm-Fe-N with finer particle size; therefore, the circularity of the Nd-Fe-B magnetic powder is 0.6-0.8.

The Sm-Fe-N magnetic powder has strong activity and is easy to oxidize within the granularity range, so that an F-containing organic matter is coated to improve the oxidation resistance of the Sm-Fe-N magnetic powder by surface treatment in the preparation process, wherein the F-containing organic matter can be fluorine-containing alkane, fluorine-containing alkene and the like.

The Nd-Fe-B series coarse magnetic powder, the Sm-Fe-N series fine magnetic powder and the binder can be used for preparing a bonded magnet with high pressing density, but the Sm-Fe-N series fine magnetic powder has the particle size of 1-12 microns, is easy to agglomerate and not easy to disperse, and has adverse effects on the distribution uniformity of fine magnet powder in the magnet forming process, the comprehensive magnetic performance of the magnet and the pressing density. Therefore, the Sm-Fe-N series fine magnetic powder is fully dispersed by adding the inorganic nano dispersing agent, so that the Sm-Fe-N series fine magnetic powder and the binder are uniformly coated on the surface of the anisotropic Nd-Fe-B series coarse magnetic powder, and the comprehensive magnetic performance, density and tissue uniformity of the composite magnet can be further improved.

A second aspect of the present invention provides a method for producing an anisotropic bonded magnet, as shown in fig. 1, comprising the steps of:

s100, preparing Nd-Fe-B series magnetic powder by using an HDDR method;

s200, preparing Sm-Fe-N series magnetic powder by a powder metallurgy method;

s300, mixing the Nd-Fe-B series magnetic powder, the Sm-Fe-N series magnetic powder, a binder and an inorganic nano dispersant according to a specific proportion to prepare mixed rubber powder;

further, as shown in fig. 2, the step of mixing the Nd-Fe-B system magnetic powder, the Sm-Fe-N system magnetic powder, the binder and the inorganic nano-dispersant in a specific ratio to prepare the rubber mixture powder includes:

s310, dissolving the binder by using an organic solvent to prepare a first organic solution;

s320, adding an inorganic nano dispersant into the first organic solution to prepare a second organic solution;

s330, adding the Sm-Fe-N magnetic powder into the second organic solution, and uniformly dispersing by using ultrasonic waves to prepare a third organic solution;

and S340, adding the Nd-Fe-B magnetic powder into the third organic solution, and fully stirring to completely volatilize the organic solvent in the third organic solution to prepare mixed rubber powder.

Further, the organic solvent includes acetone.

S400, preparing the mixed rubber powder into the composite rare earth anisotropic bonded magnet through mould pressing, injection, calendering or extrusion.

Further, the step of preparing the Sm-Fe-N system magnetic powder further includes coating an organic substance containing F on the surface of the Sm-Fe-N system magnetic powder, as shown in fig. 3: :

adding the Sm-Fe-N magnetic powder into an organic solution containing F organic matters, and fully stirring to prepare a fully stirred organic solution;

and completely volatilizing the organic solvent in the fully stirred organic solution to ensure that the F-containing organic matter is coated on the surface of the Sm-Fe-N magnetic powder.

The present invention will be described in detail below with reference to specific examples.

Selecting Nd-Fe-B series magnetic powder prepared by an HDDR method, wherein the maximum magnetic energy product is 38MGOe, the intrinsic coercive force is 13.5kOe, and the average particle diameter is 140 micrometers; Sm-Fe-N series magnetic powder prepared by a powder metallurgy method is selected, the maximum magnetic energy product is 36MGOe, the intrinsic coercive force is 11.0kOe, and the average particle diameter is 3 microns; selecting acetone as an organic solvent; epoxy resin is selected as the binder.