阅读说明：本技术 一种纳米复合永磁材料的制备方法 (Preparation method of nano composite permanent magnetic material ) 是由 王凤青 张健 李艳鹏 张耀 池建义 于 2020-03-19 设计创作，主要内容包括：本发明涉及一种纳米复合永磁材料的制备方法,本发明将R-Cu合金添加到SmCo/Fe(Co)非晶结构和晶化物中,通过Sm-(Co,Cu)晶化相的形成与Sm、Cu元素在软硬磁晶粒间富集,实现了SmCo/Fe(Co)纳米复合材料室温矫顽力的提高；通过Cu元素进入硬磁晶格形成Sm-(Co,Cu)晶化相,提升了SmCo/Fe(Co)复合材料矫顽力的高温稳定性并将SmCo/Fe(Co)材料晶化温度和制备温度降低至500℃以下,最低可至400～425℃。提高室温矫顽力和矫顽力的高温稳定性,使得本发明具有开发高磁能积耐高温纳米复合永磁材料的制备优势；降低制备温度,具有低能耗的节能型制备优势,使本发明非常适合在低能耗下开发高软磁低稀土、高磁能积的耐高温纳米复合永磁材料。(The invention relates to a method for preparing a nano composite permanent magnetic material, which adds R-Cu alloy into a SmCo/Fe (Co) amorphous structure and a crystallized substance, and realizes the improvement of the room-temperature coercive force of the SmCo/Fe (Co) nano composite material through the formation of Sm- (Co, Cu) crystallized phase and the enrichment of Sm and Cu elements among soft and hard magnetic crystal grains; cu enters into hard magnetic crystal lattices to form Sm- (Co, Cu) crystallization phases, so that the high-temperature stability of the coercive force of the SmCo/Fe (Co) composite material is improved, and the crystallization temperature and the preparation temperature of the SmCo/Fe (Co) composite material are reduced to be below 500 ℃ and can be as low as 400-425 ℃. The coercive force at room temperature and the high-temperature stability of the coercive force are improved, so that the preparation method has the preparation advantage of developing a high-magnetic energy product high-temperature-resistant nano composite permanent magnetic material; the preparation temperature is reduced, and the energy-saving preparation advantage of low energy consumption is achieved, so that the invention is very suitable for developing the high-temperature-resistant nano composite permanent magnetic material with high soft magnetism, low rare earth and high magnetic energy product under low energy consumption.)

1. A method for preparing a nano composite permanent magnetic material is characterized by comprising the following steps:

(1) mixing R-Cu alloy powder, hard magnetic raw material powder and soft magnetic raw material powder according to a ratio, and performing high-energy ball milling on the obtained mixed powder to obtain amorphous matrix mixed powder with non-crystallized hard magnetic grains and nano-scaled soft magnetic grains;

(2) and (2) heating and crystallizing the amorphous matrix mixed powder obtained in the step (1), and converting an amorphous phase in the amorphous matrix mixed powder into a crystallized state to obtain the nano composite permanent magnetic material.

2. The method for preparing a nanocomposite permanent magnetic material according to claim 1, characterized in that: the R-Cu alloy is an alloy of a rare earth element and a Cu element, and in the R-Cu alloy, the addition ratio of the R to the Cu element is (100-y): y is more than or equal to 0 and less than or equal to 100.

3. The method of preparing a nanocomposite, permanent magnetic material of claim 2, characterized in that: the rare earth element is at least one of Sm and Pr elements.

4. The method for preparing a nanocomposite permanent magnetic material according to claim 1, characterized in that: the addition amount of the R-Cu alloy powder is as follows: the R-Cu alloy powder accounts for 0.1-15% of the total amount of the hard magnetic raw material powder and the soft magnetic raw material powder.

5. The method for preparing a nanocomposite permanent magnetic material according to claim 4, characterized in that: the addition amount of the R-Cu alloy powder is as follows: the R-Cu alloy powder accounts for 0.5 to 5 percent of the total amount of the hard magnetic raw material powder and the soft magnetic raw material powder.

6. The method for preparing a nanocomposite permanent magnetic material according to any of claims 1 to 5, characterized in that: the mass ratio of the hard magnetic raw material powder to the soft magnetic raw material powder is (10:0.1) - (5: 5).

7. The method for preparing a nanocomposite permanent magnetic material according to any of claims 1 to 5, characterized in that: the hard magnetic phase in the hard magnetic raw material powder is SmCo₂、SmCo₃、Sm₂Co₇，SmCo₅、SmCo₇、SmCo₁₂、(Sm,Pr)Co₅、Sm(Fe,Co)₃、Sm(Fe,Co)₇One or more of a type phase structure.

8. The method for preparing a nanocomposite permanent magnetic material according to any of claims 1 to 5, characterized in that: the soft magnetic raw material powder is one or more of Fe, Co and Fe-Co soft magnetic powder, the atomic percentage of Fe and Co elements is (100-x) x, and x is more than or equal to 0 and less than or equal to 100.

9. The method for preparing a nanocomposite permanent magnetic material according to any of claims 1 to 5, characterized in that: the high-energy ball milling process is carried out under the protection of inert gas or under the vacuum condition; the heating crystallization treatment is carried out under the anaerobic condition, wherein the anaerobic condition comprises a vacuum condition, an inert gas condition and a reducing gas condition.

10. The method for preparing a nanocomposite permanent magnetic material according to any of claims 1 to 5, characterized in that: the nano composite permanent magnetic material comprises nano composite permanent magnetic powder and a nano composite permanent magnetic block, and when the nano composite permanent magnetic material is the nano composite permanent magnetic block, the nano composite permanent magnetic block is a low-density/full-density composite permanent magnetic block obtained by applying a pressure of 1-2600 MPa to amorphous matrix powder in a heating crystallization process or after heating crystallization is completed, or a bonded magnet formed by mixing and pressing crystallized powder and a non-magnetic material.

Technical Field

The invention relates to a preparation method of a nano composite permanent magnetic material, in particular to a preparation method of a SmCo/Fe (Co) nano composite permanent magnetic material with higher coercive force.

Background

Compared with the traditional hard magnetic single-phase permanent magnetic material, the isotropic nanocrystalline composite permanent magnetic material composed of the soft magnetic phase and the hard magnetic phase has the advantages of low rare earth content, short preparation period, high magnetic consistency, near net shaping and the like, and is widely applied to the application fields of various precise motors and micro special motors in information industry, office automation, consumer electronics, household appliances, sensors, automobiles and the like. The most widely used isotropic permanent magnetic material in the market is Nd-Fe-B/Fe type nano material, the magnetic energy product is usually 8-17 MGOe, and the Nd is applied₂Fe₁₄Influence of Curie temperature of phase B (T)_c310 ℃) below 150 ℃, the magnetism of the permanent magnet is sharply reduced when the temperature is above 200 ℃, and the magnetism basically disappears when the temperature is above 300 ℃, so that the application requirement of the market on the high-temperature resistant permanent magnet above 200 ℃, especially above 300 ℃ is difficult to meet.

As an important isotropic nanocrystalline composite permanent magnet material, a SmCo/Fe (Co) permanent magnet material consisting of a Sm-Co hard magnetic phase and a Fe (Co) soft magnetic phase has higher Curie temperature (T) than the Nd-Fe-B nanocrystalline composite permanent magnet material commonly used in the market_c> 700 ℃) and can be obtained at a lower hard magnetic phase contentThe room temperature magnetic energy product (such as 18-19 MGOe), so the method has wide prospect in the aspects of room temperature and high temperature application.

However, the isotropic SmCo/fe (co) nanocomposite permanent magnet material prepared in the prior art is generally low in room-temperature coercivity and poor in high-temperature stability, and meanwhile, the phenomenon that the coercivity and the magnetic energy product are reduced more seriously due to high-temperature demagnetization when the room-temperature coercivity is lower exists, so that the high-temperature magnetic energy product of the existing isotropic SmCo/fe (co) nanocomposite permanent magnet material at 300 ℃ is far lower than the room-temperature magnetic energy product level thereof, and therefore, the isotropic SmCo/fe (co) nanocomposite permanent magnet material has a great challenge in meeting the use requirements of the market on high-temperature ferromagnetic materials. In addition, the energy consumption and the preparation cost can be greatly reduced by reducing the preparation temperature, and the preparation temperature is influenced by the type and the crystallization temperature of the SmCo/Fe (Co) nano composite material, so that the preparation temperature of the high-performance SmCo/Fe (Co) nano composite material of 18-19 MGOe is usually increased to over 500 ℃ and is difficult to control within 500 ℃, and the energy consumption problem caused by high preparation temperature is very serious.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art and provides a preparation method of a nano composite permanent magnetic material, which improves the coercivity at room temperature and the high-temperature stability of the coercivity and reduces the preparation temperature by adding an R-Cu alloy.

The technical scheme adopted by the invention for solving the technical problems is as follows: a method for preparing a nano composite permanent magnetic material is characterized by comprising the following steps:

(1) mixing R-Cu alloy powder, hard magnetic raw material powder and soft magnetic raw material powder according to a ratio, and carrying out high-energy ball milling on the obtained mixed material to obtain amorphous matrix mixed powder with non-crystallized hard magnetic grains and nano-scaled soft magnetic grains;

(2) and (2) heating and crystallizing the amorphous matrix mixed powder obtained in the step (1), and converting an amorphous phase in the amorphous matrix mixed powder into a crystallized state to obtain the nano composite permanent magnetic material.

The above-mentioned hard magnetic crystal grain amorphization includes all cases where hard magnetic crystal grains are amorphized and transformed, a part of hard magnetic crystal grains are amorphized and transformed, a trace amount of hard magnetic crystal grains are amorphized and transformed, and a part of hard magnetic crystal grain regions are amorphized and transformed.

In the above scheme, the R-Cu alloy is an alloy of a rare earth element and a Cu element. The Cu element and the rare earth element have the important function of improving the coercive force by magnetic pinning in the NdFeB magnet and the SmCo magnet, and according to the similar phase solubility principle, when the Cu element is mixed into the rare earth element which is the same as or similar to the main phase Sm element, the Cu element and the alloy are more beneficial to realizing the element exchange between the Cu element and the SmCo hard magnet, so that the uniform distribution of the doped phase in the main phase and the magnetic pinning improvement function are more beneficial to being improved; in addition, the melting point of the rare earth-Cu alloy is generally lower, the higher metal plasticity and deformability can be still maintained below 500 ℃, the full densification of the magnet at a lower temperature can be promoted, and the Cu element entering the hard magnetic lattice can also play a role in reducing the crystallization temperature of a nonmagnetic phase. Therefore, after the R-Cu alloy is added, the invention has high development potential in the aspects of improving the forming temperature of the two-phase magnet and improving the coercive force of the magnet, and is more beneficial to obtaining the nanocrystalline two-phase magnetic powder and the bulk magnet with more excellent magnetism at lower preparation temperature.

Preferably, the rare earth element is at least one element selected from Sm and Pr elements.

Preferably, the addition amount of the R-Cu alloy powder is as follows: the R-Cu alloy powder accounts for 0.1-15% of the total amount of the hard magnetic raw material powder and the soft magnetic raw material powder. If the addition amount of the R-Cu alloy powder is too small, the coercive force improvement effect is not obvious, and if the addition amount is too large, the remanence of the magnet is reduced too much.

More preferably, the addition amount of the R-Cu alloy powder is: the proportion of the R-Cu alloy powder to the total amount of the hard magnetic raw material powder and the soft magnetic raw material powder is 1 to 5 percent.

Preferably, the mass ratio of the hard magnetic raw material powder to the soft magnetic raw material powder is (10:0.1) to (5: 5).

Preferably, the hard magnetic phase in the hard magnetic raw material powder is SmCo₂、SmCo₃、Sm₂Co₇，SmCo₅、SmCo₇、 SmCo₁₂、(Sm,Pr)Co₅、Sm(Fe,Co)₃、Sm(Fe,Co)₇One or more of a type phase structure.

Preferably, the soft magnetic raw material powder is one or more of Fe, Co and Fe-Co soft magnetic powder, and the atomic percentage of Fe and Co elements is (100-x) x, wherein x is more than or equal to 0 and less than or equal to 100.

Preferably, the high-energy ball mill is used in an apparatus including, but not limited to, a one-dimensional or three-dimensional vibration ball mill, a planetary ball mill; the ball milling time, the ball material ratio and the rotating speed of the ball mill are matched with the technological parameters of the ball milling device, the material of the ball milling tank, the material of the grinding balls, the size of the grinding balls and the like, and the method is not limited. Preferably, the high-energy ball milling is carried out in a three-dimensional vibration ball mill, a ball milling tank is a hard alloy tank, grinding balls are hard alloy balls, the ball milling process is carried out under the protection of inert gas or under the vacuum condition, the rotating speed of the ball mill is higher than 400rpm, the ball-to-material ratio is (15:1) - (30:1), and the ball milling time is 2-5 hours. The heating crystallization treatment is a treatment mode of converting an amorphous phase in the amorphous matrix mixed powder into a crystallization state by using a heating mode; the treatment environment is anaerobic and comprises a vacuum environment or a high-purity inert gas environment; in the crystallization treatment, only heating may be performed, or crystallization control conditions such as a magnetic field and pressure may be applied while heating. The temperature of the heating crystallization treatment is 350-800 ℃, preferably below 650 ℃.

Preferably, the nano composite permanent magnetic material comprises nano composite permanent magnetic powder and a nano composite permanent magnetic block, when the nano composite permanent magnetic material is the nano composite permanent magnetic block, the preparation method further comprises a pressure forming treatment process, wherein in the process of heating and crystallizing the amorphous matrix powder or after the heating and crystallizing are completed, the pressure of 1-2600 MPa is applied to the powder to obtain a low-density or full-density composite permanent magnetic block; the nano composite permanent magnet block can also be a bonded magnet formed by mixing and pressing crystallized powder and non-magnetic materials such as epoxy resin and the like.

When the heating crystallization process does not relate to compression molding, the prepared material is permanent magnet powder; when the heating crystallization process is combined with the pressing molding process, the prepared material is a permanent magnet block. The heating crystallization process may be combined with the compression molding process, and includes different combinations of the heating crystallization process and the compression molding process, for example, the amorphous matrix mixed powder is heated and crystallized first and then heated and pressurized for molding, the amorphous matrix mixed powder is simultaneously subjected to amorphous crystallization and compression molding under the heating and pressurizing conditions, the amorphous matrix mixed powder is compressed and molded first and then heated for crystallization, and the like.

Preferably, the permanent magnet blocks may be subjected to a thermal annealing treatment to improve the uniformity of the permanent magnet blocks or to achieve a further increase in the magnetic energy product of the permanent magnet blocks.

The invention also comprises a non-pressure treatment process, and the nano composite permanent magnetic powder is directly obtained after the ball-milled magnetic powder is heated and crystallized.

Compared with the prior art, the invention has the advantages that: according to the invention, the R-Cu alloy is added into a SmCo/Fe (Co) amorphous structure and a crystal, and a Sm- (Co, Cu) crystal phase and an Sm and Cu element are enriched among soft and hard magnetic crystal grains by entering a Cu element into a hard magnetic crystal lattice, so that the room-temperature coercive force and the high-temperature stability of a magnet of the SmCo/Fe (Co) nano composite material are improved; the preparation temperature of the SmCo/Fe (Co) composite magnetic powder and the full-density magnet is reduced to 500 ℃ or below, and can be as low as 400-425 ℃ at most by reducing the crystallization temperature of amorphous hard magnetic and improving the low-temperature plasticity and deformability of the powder. The room-temperature coercive force of the nano composite magnet is improved, and the high-temperature stability is improved, so that the preparation method has the preparation advantage of developing a high-performance high-temperature-resistant nano composite permanent magnet material; the preparation temperature is reduced, so that the preparation method has the advantages of energy saving and low cost; particularly, in the low-cost low-rare earth high-soft magnetic nano composite material with the soft magnetic content of 15-30%, the preparation temperature can be reduced, the room-temperature coercive force can be increased, a high magnetic energy product material reaching 21-23 MGOe can be obtained, and the material is obviously higher than neodymium iron boron isotropic permanent magnetic powder and permanent magnetic block bodies which are widely used in the market and have the magnetic energy product of 8-19 MGOe, so that the invention is also very suitable for developing the high-temperature resistant nano composite permanent magnetic material with high soft magnetic, low rare earth and high magnetic energy product under low energy consumption.

Drawings

FIG. 1 is a graph showing a comparison of magnetic properties of materials prepared in example 1 of the present invention and comparative example 1;

FIG. 2 is a graph showing another comparison of magnetic properties of the materials prepared in example 1 of the present invention and comparative example 1.

Detailed Description

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