阅读说明：本技术 一种海尔贝克磁体的制备方法 (Preparation method of Halbach magnet ) 是由 潘佳静 张民 吕向科 沈国迪 杨树松 李义国 苏晗翀 裘文超 于 2020-12-09 设计创作，主要内容包括：本发明公开了一种海尔贝克磁体的制备方法,通过先在模具的长方体型腔的任意一侧形成N极和S极交替排布的磁场,当长方体型腔中填入磁粉后,在惰性气体保护下,将磁粉在该磁场下进行取向,然后再进行真空烧结处理和热处理,得到烧结钕铁硼磁体,最后将得到的烧结钕铁硼磁体按取向特征进行充磁,得到海尔贝克磁体；优点是预设设置特定的磁场,然后采用先填粉、再取向、接着烧结、最后充磁的方式制备得到海尔贝克磁体,海尔贝克磁体一体成型得到,相对于现有制备方法省略了先分别制备多个小块磁体后再进行组装的过程,工艺过程简单,生产效率得到了显著提升,大大降低了生产工艺成本。(The invention discloses a preparation method of a Halbach magnet, which comprises the steps of forming a magnetic field with alternately arranged N poles and S poles on any side of a cuboid cavity of a mold, after filling magnetic powder into the cuboid cavity, orienting the magnetic powder in the magnetic field under the protection of inert gas, then carrying out vacuum sintering treatment and heat treatment to obtain a sintered NdFeB magnet, and finally magnetizing the obtained sintered NdFeB magnet according to the orientation characteristic to obtain the Halbach magnet; the Halbach magnet has the advantages that a specific magnetic field is preset, the Halbach magnet is prepared by the modes of powder filling, orientation, sintering and magnetizing, and the Halbach magnet is integrally formed, so that compared with the existing preparation method, the process that a plurality of small magnets are prepared respectively and then assembled is omitted, the technical process is simple, the production efficiency is obviously improved, and the production technical cost is greatly reduced.)

1. A preparation method of a Halbach magnet is characterized in that a magnetic field with N poles and S poles alternately arranged is formed on any one side of a cuboid cavity of a mold, after the cuboid cavity is filled with magnetic powder, the magnetic powder is oriented in the magnetic field under the protection of inert gas, then vacuum sintering treatment and heat treatment are carried out to obtain a sintered NdFeB magnet, and finally the obtained sintered NdFeB magnet is magnetized according to the orientation characteristic to obtain the Halbach magnet.

2. The method according to claim 1, wherein the rectangular cavity has at least one open end, and the mold is made of a non-magnetic material having a melting point of 1200 ℃ or higher.

3. The method according to claim 1, wherein the magnetic field is formed by an oriented magnetic pole group in which N poles and N S poles are alternately arranged, and N is an integer of 2 or more.

4. A method of forming a halbach magnet as claimed in claim 1 wherein the magnetic field generates a maximum field strength in the cuboid cavity of greater than 1T.

5. The method of claim 1, wherein the magnetic powder in the rectangular mold cavity has a density of 2.5g/cm³-3.5g/cm³。

6. The method according to claim 5, wherein the magnetic powder in the rectangular cavity has a density of 2.5g/cm by means of, but not limited to, tapping and pre-pressing³-3.5g/cm³。

7. The method of claim 1, wherein the oriented magnetic powder in the rectangular mold cavity is continuously arranged along the direction of the magnetic field lines in the easy magnetization direction.

8. The method for preparing a halbach magnet according to claim 1, wherein the temperature of the vacuum sintering treatment is 980-1100 ℃, the sintering time is 2-10 h, the heat treatment is a two-stage tempering treatment, and the two-stage tempering process comprises: treating for 1.5 to 3 hours at the temperature of 870 to 950 ℃, and then treating for 2 to 5 hours at the temperature of 440 to 560 ℃.

Technical Field

The invention relates to a preparation method of a magnet, in particular to a preparation method of a Halbach magnet.

Background

Halbach Array is a magnet structure and is an approximate ideal structure in engineering. Magnets implemented with halbach arrays are known as halbach array magnets, with the goal of producing the strongest magnetic field with the least amount of magnet. In the Halbach array magnet, permanent magnets with different magnetization directions are arranged according to a certain sequence, so that the magnetic field on one side of the Halbach array magnet is obviously enhanced, and the magnetic field on the other side of the Halbach array magnet is obviously weakened.

Currently, halbach magnets have become the material of choice for high speed and high precision control motors. With the automation and precision of equipment and the development of permanent magnet motor design and manufacturing technology and control technology, a high-performance permanent magnet servo motor adopting a Halbach magnet has wide application prospects in the fields of high and new generation information technology, new energy technology, numerical control machines, household appliances, computers and the like.

The conventional method for manufacturing halbach magnets is to manufacture a plurality of small magnets and then assemble the small magnets together. For example, a halbach array magnet assembly process disclosed in chinese patent application publication No. CN111009407A, includes the steps of: the method comprises the following steps: selecting a plurality of permanent magnet blanks with different orientations; step two: processing a plurality of permanent magnet blanks with different orientations to a specified size along an assembling direction; step three: assembling a plurality of processed permanent magnet blanks with different orientations in a Halbach array to obtain assembled blanks; step four: processing the other two sizes of the assembled blank to the required sizes; step five: processing the surface of the assembled blank; step six: and magnetizing the assembled blank to obtain the Halbach array magnet assembly. In the method, the assembly mode of non-magnetization is adopted, so that the assembly difficulty can be reduced, the assembly efficiency is improved to a certain extent, but the assembly process is still complex, the whole process is still complex, the production efficiency is still low, and the production cost is high.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of a Halbach magnet, which has the advantages of simple process, high production efficiency and low production cost.

The technical scheme adopted by the invention for solving the technical problems is as follows: a preparation method of a Halbach magnet comprises the steps of firstly forming a magnetic field with N poles and S poles alternately arranged on any side of a cuboid cavity of a mold, after the cuboid cavity is filled with magnetic powder, orienting the magnetic powder under the magnetic field under the protection of inert gas, then carrying out vacuum sintering treatment and heat treatment to obtain a sintered NdFeB magnet, and finally magnetizing the obtained sintered NdFeB magnet according to orientation characteristics to obtain the Halbach magnet.

The cuboid cavity is provided with at least one opening, and the die is made of a non-magnetic material with the melting point of more than or equal to 1200 ℃.

The magnetic field is formed by an oriented magnetic pole group formed by alternately arranging N N poles and N S poles, wherein N is an integer greater than or equal to 2.

The maximum magnetic field intensity generated by the magnetic field in the cuboid cavity is more than 1T.

The density of the magnetic powder in the cuboid cavity is 2.5g/cm³-3.5g/cm³。

The magnetic powder in the cuboid cavity adopts a mode of vibration compaction and prepressing without limitation to enable the density of the magnetic powder to reach 2.5g/cm³-3.5g/cm³。

The magnetic powder in the cuboid cavity is continuously arranged along the direction of the magnetic force line in the oriented easy magnetization direction.

The temperature of the vacuum sintering treatment is 980-1100 ℃, the sintering time is 2-10 h, the heat treatment is two-stage tempering treatment, and the two-stage tempering process comprises the following steps: treating for 1.5 to 3 hours at the temperature of 870 to 950 ℃, and then treating for 2 to 5 hours at the temperature of 440 to 560 ℃.

Compared with the prior art, the invention has the advantages that the magnetic field with the N poles and the S poles alternately arranged is formed on any side of the cuboid cavity of the mould, after the magnetic powder is filled in the cuboid cavity, the magnetic powder is oriented under the protection of inert gas, then the vacuum sintering treatment and the heat treatment are carried out to obtain the sintered Nd-Fe-B magnet, finally the obtained sintered Nd-Fe-B magnet is magnetized according to the orientation characteristic to obtain the Halbach magnet, the method of the invention presets the specific magnetic field, then the Halbach magnet is prepared by adopting the modes of filling the powder, reorienting, sintering and finally magnetizing, the Halbach magnet is obtained by integral molding, compared with the existing preparation method, the process of respectively preparing a plurality of small magnets and then assembling is omitted, the process is simple, and the production efficiency is obviously improved, greatly reduces the production process cost.

Drawings

Fig. 1 is an orientation schematic view of a method for producing a halbach magnet according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

The first embodiment is as follows: a preparation method of a Halbach magnet, the grade of the Halbach magnet is 38SH, comprising the following steps:

step 1, preparing a mold 1, wherein the mold 1 is made of ceramic, a cuboid cavity with an opening at the upper end is arranged on the mold 1, the cuboid cavity has the size of 80mm in length, 30mm in width and 20mm in height, an oriented magnetic pole group 2 is arranged on the upper side of the cuboid cavity, the oriented magnetic pole group 2 is realized by adopting a pulse 4-pole oriented coil, and the pulse 4-pole oriented coil comprises 2N-pole oriented coils and 2S-pole oriented coils which are alternately arranged to generate a magnetic field with alternately arranged N poles and S poles;

step 2, feeding the magnetic powder into a cuboid cavity under the inert gas protection atmosphere, and adopting a compaction mode to enable the density of the magnetic powder in the cuboid cavity to reach 2.5g/cm³Obtaining compact powder 3; at the moment, the magnetic powder in the cuboid cavity is continuously arranged along the direction of the magnetic force line in the oriented easy magnetization direction;

step 3, under the inert gas protection atmosphere, adopting an oriented magnetic pole group to generate an oriented magnetic field to orient the dense powder 3 to obtain oriented powder, wherein the strength of the oriented magnetic field is 1.5T; the orientation diagram is shown in fig. 1, wherein S in fig. 1 represents an S-pole orientation coil, and N represents an N-pole orientation coil;

step 4, putting the mould 1 filled with the oriented powder into a vacuum sintering furnace, wherein the vacuum degree is superior to 5 multiplied by 10^-2Pa, firstly sintering for 4.5h at 1075 ℃, and then carrying out two-stage tempering treatment, wherein the tempering treatment process comprises the following steps: treating at 900 ℃ for 3h, filling argon, cooling to room temperature, heating to 500 ℃ for treatment for 4h, filling nitrogen, and cooling to room temperature to obtain a sintered neodymium-iron-boron magnet;

and step 5, according to the orientation characteristics of the sintered NdFeB magnet, adopting a pulse 4-pole magnetizing coil comprising 2N-pole magnetizing magnetic poles and 2S-pole magnetizing magnetic poles which are alternately arranged to generate a magnetizing magnetic field, and magnetizing the sintered NdFeB magnet to obtain the Halbach magnet.

Example two: a preparation method of a Halbach magnet, the grade of the Halbach magnet is 38SH, comprising the following steps:

step 1, preparing a mold 1, wherein the mold 1 is made of graphite, a cuboid cavity with an opening at the upper end is arranged on the mold 1, the cuboid cavity is 80mm long, 30mm wide and 15mm high, an oriented magnetic pole group 2 is arranged on the upper side of the cuboid cavity, the oriented magnetic pole group 2 is realized by adopting a pulse 6-pole oriented coil, and the pulse 6-pole oriented coil comprises 3N-pole oriented coils and 3S-pole oriented coils which are alternately arranged to generate a magnetic field with alternately arranged N poles and S poles;

step 2, feeding the magnetic powder into a cuboid cavity under the inert gas protection atmosphere, and pre-pressing the magnetic powder in the cuboid cavity until the density reaches 3.0g/cm³Obtaining compact powder 3; at the moment, the magnetic powder in the cuboid cavity is continuously arranged along the direction of the magnetic force line in the oriented easy magnetization direction;

step 3, under the inert gas protection atmosphere, adopting an oriented magnetic pole group to generate an oriented magnetic field to orient the dense powder 3 to obtain oriented powder, wherein the strength of the oriented magnetic field is 1.5T; the orientation diagram is shown in fig. 1, wherein S in fig. 1 represents an S-pole orientation coil, and N represents an N-pole orientation coil;

step 4, putting the mould 1 filled with the oriented powder into a vacuum sintering furnace, wherein the vacuum degree is superior to 5 multiplied by 10^-2Pa, firstly sintering for 4 hours at 1077 ℃, and then carrying out two-stage tempering treatment, wherein the tempering treatment process comprises the following steps: treating at 950 ℃ for 2h, filling argon, cooling to room temperature, heating to 450 ℃ for treatment for 5h, filling nitrogen, and cooling to room temperature to obtain a sintered neodymium-iron-boron magnet;

and step 5, according to the orientation characteristics of the sintered NdFeB magnet, adopting a pulse 6-pole magnetizing coil comprising 3N-pole magnetizing magnetic poles and 3S-pole magnetizing magnetic poles which are alternately arranged to generate a magnetizing magnetic field, and magnetizing the sintered NdFeB magnet to obtain the Halbach magnet.

Example three: a preparation method of a Halbach magnet, the Halbach magnet has a mark of 45SH, and comprises the following steps:

step 1, preparing a mold 1, wherein the mold 1 is made of graphite, a cuboid cavity with an opening at the upper end is arranged on the mold 1, the cuboid cavity is 80mm long, 30mm wide and 15mm high, an oriented magnetic pole group 2 is arranged on the upper side of the cuboid cavity, the oriented magnetic pole group 2 is realized by adopting a pulse 6-pole oriented coil, and the pulse 6-pole oriented coil comprises 3N-pole oriented coils and 3S-pole oriented coils which are alternately arranged to generate a magnetic field with alternately arranged N poles and S poles;

step 2, feeding the magnetic powder into a cuboid cavity under the inert gas protection atmosphere, and pre-pressing the magnetic powder in the cuboid cavity until the density reaches 3.0g/cm³Obtaining compact powder 3; at the moment, the magnetic powder in the cuboid cavity is continuously arranged along the direction of the magnetic force line in the oriented easy magnetization direction;

step 3, under the inert gas protection atmosphere, adopting an oriented magnetic pole group to generate an oriented magnetic field to orient the dense powder 3 to obtain oriented powder, wherein the strength of the oriented magnetic field is 1.5T; the orientation diagram is shown in fig. 1, wherein S in fig. 1 represents an S-pole orientation coil, and N represents an N-pole orientation coil;

step 4, putting the mould 1 filled with the oriented powder into a vacuum sintering furnace, wherein the vacuum degree is superior to 5 multiplied by 10^-2Pa, firstly sintering for 4 hours at 1077 ℃, and then carrying out two-stage tempering treatment, wherein the tempering treatment process comprises the following steps: treating at 950 ℃ for 2h, filling argon, cooling to room temperature, heating to 450 ℃ for treatment for 5h, filling nitrogen, and cooling to room temperature to obtain a sintered neodymium-iron-boron magnet;

and step 5, according to the orientation characteristics of the sintered NdFeB magnet, adopting a pulse 6-pole magnetizing coil comprising 3N-pole magnetizing magnetic poles and 3S-pole magnetizing magnetic poles which are alternately arranged to generate a magnetizing magnetic field, and magnetizing the sintered NdFeB magnet to obtain the Halbach magnet.

Example four: a preparation method of a Halbach magnet, the grade of the Halbach magnet is 38SH, comprising the following steps:

step 1, preparing a mold 1, wherein the mold 1 is made of austenitic stainless steel, a cuboid cavity with an opening at the upper end is arranged on the mold 1, the cuboid cavity is 100mm in length, 30mm in width and 10mm in height, an oriented magnetic pole group 2 is arranged on the upper side of the cuboid cavity, the oriented magnetic pole group 2 is realized by adopting pulse 8-pole oriented coils, and the pulse 8-pole oriented coils comprise 4N-pole oriented coils and 4S-pole oriented coils which are alternately arranged to generate a magnetic field with alternately arranged N poles and S poles;

step 2, feeding the magnetic powder into a cuboid cavity under the inert gas protection atmosphere, and pre-pressing the magnetic powder in the cuboid cavity until the density reaches 3.5g/cm³Obtaining compact powder 3, wherein the magnetic powder in the cuboid cavity is continuously arranged along the direction of the magnetic force line in the oriented easy magnetization direction;

step 3, under the inert gas protection atmosphere, adopting an oriented magnetic pole group to generate an oriented magnetic field to orient the dense powder 3 to obtain oriented powder, wherein the strength of the oriented magnetic field is 1.5T; the orientation diagram is shown in fig. 1, wherein S in fig. 1 represents an S-pole orientation coil, and N represents an N-pole orientation coil;

step 4, putting the mould 1 filled with the oriented powder into a vacuum sintering furnace, wherein the vacuum degree is superior to 5 multiplied by 10^-2Pa, firstly sintering for 4 hours at 1078 ℃, and then carrying out two-stage tempering treatment, wherein the tempering treatment process comprises the following steps: treating at 900 ℃ for 3h, filling argon, cooling to room temperature, heating to 500 ℃ for treatment for 4h, filling nitrogen, and cooling to room temperature to obtain a sintered neodymium-iron-boron magnet;

and step 5, according to the orientation characteristics of the sintered NdFeB magnet, adopting a pulse 8-pole magnetizing coil comprising 4N-pole magnetizing magnetic poles and 4S-pole magnetizing magnetic poles which are alternately arranged to generate a magnetizing magnetic field, and magnetizing the sintered NdFeB magnet to obtain the Halbach magnet.

Example five: a preparation method of a Halbach magnet, the grade of the Halbach magnet is 38SH, comprising the following steps:

step 1, preparing a mold 1, wherein the mold 1 is made of austenitic stainless steel, a cuboid cavity with an opening at the upper end is arranged on the mold 1, the cuboid cavity is 100mm in length, 30mm in width and 10mm in height, an oriented magnetic pole group 2 is arranged on the upper side of the cuboid cavity, the oriented magnetic pole group 2 is realized by adopting pulse 10-pole oriented coils, and the pulse 10-pole oriented coils comprise 5N-pole oriented coils and 5S-pole oriented coils which are alternately arranged to generate a magnetic field with alternately arranged N poles and S poles;

step 2, feeding the magnetic powder into a cuboid cavity under the inert gas protection atmosphere, and pre-pressing the magnetic powder in the cuboid cavity until the density reaches 3.5g/cm³Obtaining compact powder 3; at the moment, the magnetic powder in the cuboid cavity is continuously arranged along the direction of the magnetic force line in the oriented easy magnetization direction;

step 3, under the inert gas protection atmosphere, adopting an oriented magnetic pole group to generate an oriented magnetic field to orient the dense powder 3 to obtain oriented powder, wherein the strength of the oriented magnetic field is 1.5T; the orientation diagram is shown in fig. 1, wherein S in fig. 1 represents an S-pole orientation coil, and N represents an N-pole orientation coil;

step 4, putting the mould 1 filled with the oriented powder into a vacuum sintering furnace, wherein the vacuum degree is superior to 5 multiplied by 10^-2Pa, firstSintering for 4h at 1078 ℃, and then carrying out two-stage tempering treatment, wherein the tempering treatment process comprises the following steps: treating at 900 ℃ for 3h, filling argon, cooling to room temperature, heating to 500 ℃ for treatment for 4h, filling nitrogen, and cooling to room temperature to obtain a sintered neodymium-iron-boron magnet;

and step 5, according to the orientation characteristics of the sintered NdFeB magnet, adopting a pulse 8-pole magnetizing coil comprising 4N-pole magnetizing magnetic poles and 4S-pole magnetizing magnetic poles which are alternately arranged to generate a magnetizing magnetic field, and magnetizing the sintered NdFeB magnet to obtain the Halbach magnet.

The halbach magnets obtained in the first to fifth embodiments were processed into magnets with a height of 4mm, and peak surface magnetic data tests were performed using an F-30 multi-dimensional magnetic field tester, respectively, and the relevant test data are shown in table 1 below:

table 1 peak value table for magnetic data of examples one to five

In table 1, columns corresponding to the magnetic pole N and the magnetic pole S respectively represent peak surface magnetic data at the N pole and the S pole corresponding to the halbach magnet. Analyzing the data in the table, the following results can be obtained: the Halbach magnet prepared by the method of the invention has surface magnetism up to 500mT and excellent magnetic property.

In conclusion, compared with the existing preparation method, the preparation method of the Halbach magnet has the advantages that the Halbach magnet has higher magnetic performance, meanwhile, the process of firstly preparing a plurality of small magnets and then assembling the small magnets is omitted, the process is simple, the production efficiency is obviously improved, and the production process cost is greatly reduced.