KR102189985B1 - Method for manufacturing nd-fe-b group permanent magnet and nd-fe-b group permanent using thereof - Google Patents

Abstract

The present invention relates to a method for manufacturing an Nd-Fe-B-based group permanent magnet, and more specifically, to the method for manufacturing an Nd-Fe-B-based group permanent magnet including the steps of: a powder manufacturing step; a temporary forming step in which an Nd-Fe-B-based permanent magnet powder is temporary-formed, so that a temporary-formed magnetic body is manufactured; and a plastic processing step in which a ferromagnetic phase Nd_2Fe_14B phase of the temporary-formed magnetic body is plastically processed, so that an Nd-Fe-B-based permanent magnet is manufactured, thereby minimizing the formation of an Nd-rich phase by controlling the atomic percentage of Nd, Fe and B.

Description

Manufacturing method of Nd-Fe-B permanent magnet and Nd-Fe-B permanent magnet manufactured thereby {METHOD FOR MANUFACTURING ND-FE-B GROUP PERMANENT MAGNET AND ND-FE-B GROUP PERMANENT USING THEREOF}

The present invention relates to a method for manufacturing a Nd-Fe-B-based permanent magnet and an Nd-Fe-B-based permanent magnet manufactured thereby, and more particularly, the atomic percentage is Nd _11-13 Fe _82-84 B _5-7 (at. %) Nd-Fe-B-based alloy ferromagnetic phase Nd ₂ Fe ₁₄ B phase using the plastic deformation of the permanent magnet manufacturing method and the Nd-Fe-B-based permanent magnet manufactured thereby.

Nd-Fe-B-based permanent magnet refers to a ferromagnetic material that does not change easily against external magnetic influences, transition metals such as iron, cobalt, nickel, etc., and neodymium, praseodymium, and gadolium with excellent magnetic force. , Dysprosium, terbium, and other rare earth elements and boron are mixed. These permanent magnets are excellent in magnetic properties such as residual magnetism, saturation magnetic flux density and coercive force, and thus various industries such as electric vehicles, hydrogen vehicles, MRI, wind power generation, automation facilities, and white home appliances It is used as a major material in the field.

In general, in the manufacturing method of a Nd-Fe-B-based permanent magnet including neodymium (Nd) as a rare earth element, iron (Fe) and boron (B) as transition metal elements, a strip manufactured by strip casting is hydrogen crushed. There is a strip casting method in which the manufactured powder is subjected to magnetic field molding and sintering, or a melt spinning method in which the powder manufactured by pulverizing a ribbon manufactured by melt spinning is subjected to temporary molding and high temperature deformation.

On the other hand, magnetic anisotropy means that the magnetic properties of a magnetic material (permanent magnet) vary depending on the direction of the crystal. In general, in the case of a magnetic material, a crystal is moved toward a specific crystal axis in a crystal that is easy to It has excellent magnetic properties when arranged. Therefore, in recent years, research on manufacturing a permanent magnet with improved magnetic properties by giving magnetic anisotropy by physically changing the crystal grain arrangement direction of the permanent magnet by plastic deformation by applying temperature and pressure to the permanent magnet has been conducted.

Conventional methods for imparting anisotropy to powders manufactured by the strip casting method and melt spinning method include applying an external magnetic field and a method of imparting anisotropy through crystal grain rotation after grain growth using a die-up set. In this case, the size of the powder is very small, ranging from several nanometers to several microns, so that the contained rare earth elements are very easy to oxidize. Therefore, control of the oxygen concentration during the process is required, resulting in complicated processes and increased cost.

Therefore, as a method to solve this problem, an invention was attempted on a method of making Nd-Fe-B powder by gas spray and giving it anisotropy by plastically deforming it, but in this case, an Nd-rich phase was created inside. Since the Nd-rich phase has a melting point of around 650°C, the Nd-rich phase disperses the load by melting in a plastic deformation process performed at a high temperature of 800°C, so it is not easy to impart anisotropy by plastic deformation.

Korean Registered Patent Publication No. 10-0241982 (Name: Rare Earth Bond Magnet and Composition for Rare Earth Bond Magnet) Republic of Korea Patent Publication No. 10-1918975 (Name: Nd-Fe-B magnet and its manufacturing method) Republic of Korea Patent Publication No. 10-1428672 (Name: manufacturing method of Nd-Fe-B magnetic powder using a gas spraying process, magnetic powder, magnetic material and method of manufacturing magnetic material)

The present invention is to solve the problems caused by the prior art as described above, and an object of the present invention is a method of manufacturing a Nd-Fe-B-based permanent magnet configured to impart magnetic anisotropy by plastic processing, and thereby It is to provide a manufactured Nd-Fe-B permanent magnet.

One aspect of a method for manufacturing a Nd-Fe-B-based permanent magnet in an embodiment of the present invention for achieving the above object is, in which Nd-Fe-B-based permanent magnet powder is manufactured, a powder manufacturing step; A temporary molding step in which the Nd-Fe-B-based permanent magnet powder is temporary-molded to produce a false-formed magnetic body; And a plastic processing step in which the false-formed magnetic body is plastically processed to produce a Nd-Fe-B-based permanent magnet. Includes.

Further, in the plastic working step, magnetic anisotropy may be imparted to the Nd-Fe-B-based permanent magnet.

In addition, in the powder manufacturing step, the atomic percentage of the Nd-Fe-B-based permanent magnet powder may be Nd _11-13 Fe _80-84 B _5-7 (at.%).

And, in the powder manufacturing step, the size of the Nd-Fe-B-based permanent magnet powder may be 5 μm to 100 μm.

In addition, in the plastic working step, the false-formed magnetic body may be plastic processed at a temperature of 800°C or higher.

Another aspect of the method for manufacturing a Nd-Fe-B-based permanent magnet according to an embodiment of the present invention,

In the method of manufacturing a Nd-Fe-B-based permanent magnet:

Nd-Fe-B-based permanent magnet powder produced by gas spraying is sintered to produce a pseudo-formed magnetic body produced by plastic processing to produce an Nd-Fe-B-based permanent magnet with magnetic anisotropy, but the atomic percentage of the permanent magnet powder This control is characterized in that the generation of the Nd-rich phase in the permanent magnet is reduced.

And, the Nd-Fe-B-based permanent magnet powder, the atomic percentage of each of neodymium (Nd), iron (Fe) and boron (B) is Nd _11-13 Fe _80-84 B _5-7 (at.%) Can be

In addition, the size of the Nd-Fe-B-based permanent magnet powder may be 5 μm to 100 μm.

In addition, the false-formed magnetic body may be plastic processed at a temperature of 800°C or higher.

In addition, the crystal grains of the Nd-Fe-B-based permanent magnet may have an aspect ratio greater than 1.5 and less than or equal to 4.0.

One aspect of the Nd-Fe-B-based permanent magnet according to an embodiment of the present invention includes an Nd-Fe-B-based permanent magnet manufactured by the method of manufacturing an Nd-Fe-B-based permanent magnet as described above.

In addition, the aspect ratio of the crystal grains of the Nd-Fe-B-based permanent magnet may be greater than 1.5 and not greater than 4.0.

In the method of manufacturing an Nd-Fe-B-based permanent magnet according to an embodiment of the present invention, the generation of Nd-rich phase is minimized by controlling the atomic percentage of Nd, Fe and B. Accordingly, according to the present invention, plastic processing of the permanent magnet is easily performed and magnetic anisotropy is imparted to the permanent magnet, so that a Nd-Fe-B-based permanent magnet with improved magnetic properties can be manufactured.

1 is a flow chart showing a method of manufacturing a Nd-Fe-B-based permanent magnet according to an embodiment of the present invention.
2 is a graph showing the aspect ratio of the Nd-Fe-B-based permanent magnet manufactured according to an embodiment of the present invention.
3 is a graph showing the change in the orientation factor of the Nd-Fe-B-based permanent magnet manufactured according to an embodiment of the present invention.
Figure 4 is a graph measuring the hardness according to the temperature of the Nd-Fe-B-based permanent magnet manufactured according to an embodiment of the present invention.
Figure 5 is a scanning electron microscope (SEM, Scanning Electron Microscope) photograph of the Nd-Fe-B-based permanent magnet manufactured according to an embodiment of the present invention.

Hereinafter, a method of manufacturing a Nd-Fe-B based permanent magnet according to the present invention will be described in more detail with reference to the accompanying drawings.

1 is a flow chart showing a method of manufacturing a Nd-Fe-B-based permanent magnet according to an embodiment of the present invention.

Referring to FIG. 1, a method of manufacturing a Nd-Fe-B-based permanent magnet according to an embodiment of the present invention includes a powder manufacturing step (S100), a temporary molding step (S200), and a plastic processing step (S300). In particular, in this embodiment, the atomic percentage of the Nd-Fe-B permanent magnet is controlled to minimize the formation of the Nd-rich phase, which dissolves during plastic processing at high temperature and limits the crystal grain arrangement of the permanent magnet to the easy magnetization axis. Magnetic anisotropy is imparted to the permanent magnet by easily performing plastic processing of the magnet.

More specifically, in the powder manufacturing step (S100), a Nd-Fe-B-based permanent magnet powder is manufactured. In this embodiment, in the powder manufacturing step (S100), Nd-Fe-B-based permanent magnet powder having an atomic percentage of Nd _11-13 Fe _80-84 B _5-7 (at.%) as described above is prepared do. In addition, the size of the Nd-Fe-B-based permanent magnet powder may be 5 μm to 100 μm. In this case, the Nd may be a metal form, an alloy form, and a form obtained by recycling Nd extracted from the waste magnet. For example, in the powder manufacturing step (S100), the atomic percentage is Nd ₁₂ Fe ₈₂ by gas spraying under conditions of a temperature of about 1500° C., a vacuum of 5x10 ^-1 torr to 5x10 ^-2 torr and an injection pressure of 40 bar to 50 bar. B ₆ (at. %) and a size of 10 μm Nd-Fe-B-based permanent magnet powder can be prepared.

And, in the temporary molding step (S200), the Nd-Fe-B-based permanent magnet powder prepared in the powder production step (S100) is temporary-molded to manufacture a false-formed magnetic body. For example, in the temporary molding step (S200), the Nd-Fe-B-based permanent magnet powder may be formed by pressure sintering at a temperature of 750° C. and a pressure of 20 MPa to 40 MPa to manufacture the pseudo-molded magnetic body. .

Finally, in the plastic working step (S300), the false-molded magnetic body manufactured in the temporary molding step (S200) is plastic-processed to produce a Nd-Fe-B-based permanent magnet. In particular, in this embodiment, since the generation of the Nd-rich phase, which dissolves during plastic processing through the atomic percentage control of Nd, Fe, and B of the Nd-Fe-B-based permanent magnet, and interferes with the arrangement of the permanent magnet grains, is minimized. In the plastic processing step (S300), plastic deformation of the permanent magnet is easily performed, so that magnetic anisotropy is imparted to the permanent magnet. For example, in the plastic working step (S300), the false-formed magnetic body is plasticized by die upset under a temperature of 800°C or higher, for example, 800°C to 1000°C and a pressure of 60Mpa. As a result, a Nd-Fe-B-based permanent magnet with magnetic anisotropy can be manufactured. Further, in the plastic working step (S300), the crystal grains of the manufactured Nd-Fe-B-based permanent magnet may have an aspect ratio greater than 1.5 and less than 4.0. Thereafter, the prepared Nd-Fe-B-based permanent magnet may be subjected to a post-treatment process such as grain diffusion and grain improvement in order to improve magnetic properties.

Hereinafter, the present invention will be described in more detail by way of manufacturing examples. These preparation examples are only for describing the present invention in more detail, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not limited to these preparation examples.

Example

<Production Example>

In the manufacturing example, in the powder manufacturing step (S100), the atomic percentage is Nd ₁₂ Fe ₈₂ B ₆ (at.%) by gas spraying under conditions of a temperature of 1500° C., a vacuum condition of 5×10 ⁻² torr and an injection pressure of 40 bar. , Nd-Fe-B-based permanent magnet powder having a size of 10 μm was prepared.

Next, in the temporary molding step (S200), the Nd-Fe-B-based permanent magnet powder prepared in the powder production step (S100) is formed by pressure sintering under a temperature of 750°C and a pressure of 30 MPa, A magnetic body was produced.

Finally, in the plastic processing step (S300), the false-formed magnetic body manufactured in the false-molding step (S200) is plasticized by a die upset under a temperature of 900°C and a pressure of 60 MPa, and magnetic anisotropy This imparted Nd-Fe-B permanent magnet was manufactured.

<Comparative Example>

In Comparative Example, a Nd-Fe-B-based permanent magnet was prepared in the same manner as in Preparation Example, but in the powder production step (S100), Nd-Fe-B having an atomic percentage of Nd _15.22 Fe _78.63 B _6.15 (at. %) System permanent magnet powder was prepared.

Experimental example

<Experimental Example 1>

2 and 3 are attached graphs showing changes in aspect ratio and orientation factor of the Nd-Fe-B-based permanent magnet manufactured according to the above preparation example.

2 and 3, in the temperature range of 800°C to 1000°C, which is the temperature condition of the plastic working step (S300), the aspect ratio of the Nd-Fe-B system was 1.25 to 2.5. . In addition, in the case of the orientation factor, which is an index indicating the alignment of crystals to the C-axis, which is an easy magnetization axis, it increases rapidly at a temperature of 800°C or higher, which is the temperature condition of the plastic processing step (S300), and plastic deformation easily proceeds, thereby causing Nd- It can be seen that the Fe-B-based permanent magnet crystal is arranged in the axis of easy magnetization.

<Experimental Example 2>

The result of measuring the hardness according to the temperature of the Nd-Fe-B-based permanent magnet manufactured according to the Preparation Example and Comparative Example is shown in FIG. 4, and a scanning electron microscope (SEM, Scanning) of the manufactured Nd-Fe-B-based permanent magnet Electron Microscope) photo is attached to FIG.

Referring to FIG. 4, in the case of the manufacturing example, the hardness was decreased at 800°C to 1000°C, which is the temperature condition of the plastic working step (S300), and in the case of the comparative example, it was impossible to measure the hardness due to melting and oxidation of the Nd-rich phase. That is, in the case of the preparation example, since the hardness value is low at 800°C to 1000°C, plastic deformation that physically changes the crystal grain arrangement direction is possible, which is melted at high temperature to create an Nd-rich phase that limits the change in the crystal grain arrangement direction. It can be inferred that this is a reduced result.

In addition, referring to FIG. 5, it can be seen that in the case of the manufacturing example, the crystal shape of the Nd-Fe-B-based English magnet is oval, and in the case of the comparative example, the crystal grain shape is close to the circular shape. In other words, in the case of the preparation example, the crystal shape was changed to an elliptical shape due to the change in the crystal grain arrangement direction due to the plastic deformation proceeding, and in the case of the comparative example, the change in the crystal grain arrangement direction did not occur because the plastic deformation did not proceed. It was observed that there was no change from the state.

Claims (12)

Nd-Fe-B-based permanent magnet powder is prepared, powder manufacturing step (S100);
A temporary molding step (S200) in which the Nd-Fe-B-based permanent magnet powder is temporary-molded to produce a false-formed magnetic body; And
The shaping of the magnetic substance ferromagnetic aqueous phase Nd ₂ Fe ₁₄ B is fired through deformation processing Nd-Fe-B-based, plastic working steps to manufacture permanent magnet (S300); Including,
In the powder manufacturing step (S100),
The size of the Nd-Fe-B-based permanent magnet powder is 5 μm to 100 μm,
In the plastic processing step (S300),
The pseudo-formed magnetic body is a method for producing a Nd-Fe-B-based permanent magnet that is plastically processed at a temperature of 800°C or higher.
The method of claim 1,
In the plastic processing step (S300),
A method of manufacturing a Nd-Fe-B-based permanent magnet in which magnetic anisotropy is imparted to the Nd-Fe-B-based permanent magnet.
The method of claim 2,
In the powder manufacturing step (S100),
The atomic percentage of the Nd-Fe-B-based permanent magnet powder is Nd _11-13 Fe _80-84 B _5-7 (at.%) Nd-Fe-B-based permanent magnet manufacturing method.
delete delete In the method of manufacturing a Nd-Fe-B-based permanent magnet:
Nd-Fe-B-based permanent magnet powder produced by gas spraying is sintered to produce a pseudo-formed magnetic body produced by plastic processing to produce an Nd-Fe-B-based permanent magnet with magnetic anisotropy, but the atomic percentage of the permanent magnet powder It is characterized in that it is used for plastic deformation that the generation of the Nd-rich phase in the permanent magnet is reduced by controlling this,
The size of the Nd-Fe-B-based permanent magnet powder is 5 μm to 100 μm,
The pseudo-formed magnetic body is a method for producing a Nd-Fe-B-based permanent magnet that is plastically processed at a temperature of 800°C or higher.
The method of claim 6,
The Nd-Fe-B-based permanent magnet powder is Nd in which the atomic percentage of each of neodymium (Nd), iron (Fe) and boron (B) is Nd _11-13 Fe _80-84 B _5-7 (at.%). -Fe-B system permanent magnet manufacturing method.
delete delete The method of claim 6,
Crystal grains of the Nd-Fe-B-based permanent magnet, an aspect ratio (Aspect ratio) of more than 1.5 and 4.0 or less Nd-Fe-B-based permanent magnet manufacturing method.
A Nd-Fe-B-based permanent magnet manufactured by the method of manufacturing an Nd-Fe-B-based permanent magnet according to any one of claims 1 to 3, 6 to 7, and 10.
The method of claim 11,
Nd-Fe-B permanent magnets with a grain aspect ratio of more than 1.5 and less than 4.0.

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