KR102317014B1 - Manufacturing method of magnetic powder and magnetic powder - Google Patents

Abstract

A method of manufacturing a magnet powder according to an embodiment of the present invention includes preparing a primary mixture by mixing neodymium oxide, boron, and a fluoride or chloride of a transition metal, and mixing iron and calcium with the primary mixture to obtain a secondary mixture Preparing a step, the secondary mixture at a temperature of 930 ° C to 970 ° C, comprising the step of heating for 5 minutes to 15 minutes.

Description

Manufacturing method of magnet powder and magnet powder TECHNICAL FIELD

The present invention relates to a method for manufacturing a magnet powder and to a magnet powder. More specifically, the method of manufacturing a transition metal-doped Nd ₂ Fe ₁₄ B-based alloy powder and the transition metal is doped with Nd ₂ Fe ₁₄ B-based alloy powder is about.

_{The NdFeB-based magnet is a permanent magnet having a composition of Nd, a rare earth element, and Nd 2} Fe ₁₄ B, a compound of iron and boron (B). Since its development in 1983, it has been used as a general-purpose permanent magnet for 30 years. These NdFeB-based magnets are used in various fields such as electronic information, automobile industry, medical equipment, energy, and transportation. In particular, it is used in products such as machine tools, electronic information devices, home appliances, mobile phones, robot motors, wind power generators, and small motors and drive motors for automobiles, in line with the recent trend of light weight and miniaturization.

For the general manufacture of NdFeB-based magnets, a strip/mold casting or melt spinning method based on magnetic powder metallurgy is known. First, in the case of the strip/mold casting method, it is a process of manufacturing an ingot by melting metals such as Nd, iron, and boron (B) through heating, coarsely pulverizing crystal grains, and manufacturing micro particles through a refinement process. . By repeating this, a powder is obtained, and an anisotropic sintered magnet is manufactured by pressing and sintering under a magnetic field.

In addition, the melt spinning method melts metal elements, then pours them into a wheel rotating at a high speed, quenches them, and after jet milling pulverization, blends them with polymers to form bonded magnets, or presses them to make magnets. However, these methods require a high-temperature melting process, a multi-step grinding process, and a process for coating the surface of the powder particles.

Recently, a method for producing a magnetic powder by a calcium reduction-diffusion method has been attracting attention. _{The crystalline Nd 2} Fe ₁₄ B powder particles were prepared by reacting at a reaction temperature of 900°C to 1200°C for 1 to 8 hours using Ca reduction-diffusion. After removing the CaO by-products through washing, the magnet powder was dried get However, when the powder is manufactured in this way, metal precursors such as Cu, Al, Ga, and Co are added in the synthesis process in order to improve the properties of the sintered magnet. At this time, while the magnet particles are synthesized, particle dispersibility is reduced due to particle agglomeration by sintering, and pulverization using high energy such as a jet mill is required.

The present disclosure relates to a method for producing a magnet powder with significantly shortened reaction time by using an exothermic oxidation-reduction reaction of _{Ca-Nd 2} O ₃ induced at a temperature of around 950 _{(H f =-23 kcal/mol), and such} An object of the present invention is to provide a magnet powder manufactured by this method. More specifically, to provide a method for producing _{a Nd 2} Fe ₁₄ B-based alloy powder in which two to three kinds of transition metals such as Cu, Al, Ga, Zr, and Co are added.

In order to solve this problem, the method of manufacturing a magnet powder according to an embodiment of the present invention comprises the steps of preparing a primary mixture by mixing neodymium oxide, boron, and fluoride or chloride of a transition metal, iron and calcium in the primary mixture adding and mixing to prepare a secondary mixture, and heating the secondary mixture at a temperature of 930 °C to 970 °C for 5 minutes to 15 minutes.

The prepared magnet powder may be _{Nd 2} Fe ₁₄ B doped with 2 to 3 types of transition metals.

The content of the fluoride or chloride of the transition metal may be 0.01 to 0.05 at% based on the total primary mixture.

The fluoride or chloride of the transition metal is AlCl ₃ /AlF ₃ , CuCl ₂ /CuF ₂ , GaCl ₃ /GaF ₃ , CoCl ₂ /CoF ₂ , CrCl ₃ /CrF ₃ , NiCl ₂ /NiF ₂ and ZrCl ₄ /ZrF _{4 As} It may be one or more selected from the group consisting of.

The magnet powder according to an embodiment of the present invention is prepared by mixing neodymium oxide, boron, and a fluoride or chloride of a transition metal to prepare a primary mixture, by sequentially adding iron and calcium to the primary mixture and mixing 2 Preparing a tea mixture, the secondary mixture at a temperature of 930 ° C to 970 ° C, may be prepared by heating for 5 minutes to 15 minutes.

As described above, the method for manufacturing the magnet powder according to this embodiment is economical because it can scale-up while remarkably shortening the reaction time, and highly dispersible Nd-based powder particles doped with 2 to 3 types of transition metals. can get Therefore, the high-energy jet mill grinding process can be omitted, _{and a fluoride film such as NdF 3} can be formed on the surface of the columnar particles during the synthesis process, so the surface treatment process is unnecessary.

1 is Nd prepared according to Example 1 _{2 . 0} Fe ₁₃ BAl _{0 . 05} Cu _{0 .05} shows a scanning electron microscope image of the magnetic powder.
Figure 2 is prepared according to Example 1 Nd _{2 . 0} Fe ₁₃ BAl _{0 . 05} Cu _{0 .05} shows the X-ray diffraction pattern of the magnetic powder.
Figure 3 is prepared according to Example 1 Nd _{2 . 0} Fe ₁₃ BAl _{0 . 05} Cu _{0 .05} shows the magnetization hysteresis loop of the magnetic powder.
Figure 4 is prepared according to Example 2 Nd _{2 . 0} Fe ₁₃ BAl _{0 . 05} Cu _{0 . 05} Ga _{0 .01} shows a scanning electron microscope image of the magnetic powder.
_{5 is Nd 2} prepared according to Example _{2. 0} Fe ₁₃ BAl _{0 . 05} Cu _{0 . 05} Ga _{0 .01} shows the X-ray diffraction pattern of the magnetic powder.
_{6 is Nd 2} prepared according to Example _{2. 0} Fe ₁₃ BAl _{0 . 05} Cu _{0 . 05} Ga _{0 .01} shows the magnetization hysteresis loop of the magnetic powder.
_{7 is Nd 2} prepared according to Comparative Example 1 _{. 3} Fe _{13 . 5} BAl _{0 . 3} shows a scanning electron microscopy image of a Cu _{0 .05} magnet powder.
_{8 is Nd 2} prepared according to Comparative Example 1 _{. 3} Fe _{13 . 5} BAl _{0 .} Of ₃ Cu _{0 .05} magnet powder shows a X-ray diffraction pattern.
_{9 is Nd 2} prepared according to Comparative Example 1 _{. 3} Fe _{13 . 5} BAl _{0 . 3} Cu _{0 .05} shows the magnetization hysteresis loop of the magnetic powder.
_{10 is Nd 2} prepared according to Comparative Example _{2. 3} Fe _{13 . 5} BZr _{0 . 075} Al _{0 .1} shows a scanning electron microscope image of the magnetic powder.
_{11 is Nd 2} prepared according to Comparative Example _{2. 3} Fe _{13 . 5} BZr _{0 . 075} Al _{0 .1} shows the X-ray diffraction pattern of the magnetic powder.

Now, a method of manufacturing a magnet powder according to an embodiment of the present disclosure will be described in detail. The manufacturing method of the magnet powder according to the present embodiment may be a manufacturing method of the Nd ₂ Fe ₁₄ B magnet powder. That is, the manufacturing method of the magnet powder according to the present embodiment may be a manufacturing method of the Nd ₂ Fe ₁₄ B-based alloy powder. Nd ₂ Fe ₁₄ B alloy powder is a permanent magnet and is sometimes referred to as a neodymium magnet.

The method for manufacturing a magnet powder according to an embodiment of the present invention comprises the steps of preparing a primary mixture by mixing fluorides or chlorides of transition metals such as neodymium oxide, boron, Cu, Al, Ga, Co, Zr, and the like; Each of iron and calcium are sequentially added to the mixture and mixed to prepare a secondary mixture, and the secondary mixture is heated at a temperature of 930°C to 970°C for 5 minutes to 15 minutes.

The manufacturing method is a mixture of neodymium oxide, boron, iron, fluoride or chloride of 2 to 3 types of transition metals, and raw materials of calcium, and Nd _{2 by reduction and diffusion of the raw materials at a temperature of 930 ° C to 970 ° C} This is a method of forming Fe _{14 B alloy powder.} Specifically, the molar ratio of neodymium oxide, boron and iron in the mixture of neodymium oxide, boron, and iron may be between 1:14:1 and 1.5:14:1. Neodymium oxide, boron, and iron are _{raw materials for manufacturing the Nd 2} Fe ₁₄ B magnet powder, and when the molar ratio is satisfied, the Nd ₂ Fe ₁₄ B alloy powder can be manufactured with a high yield. If the molar ratio is 1:14:1 or less, there is a problem in that Nd-rich grain boundary phase is not formed and alpha phase Fe is formed. may be changed to Nd(OH) ₃ or NdH ₂ , or Nd-Ca may be formed. In addition, the reduced Nd during the synthesis process may cause particle aggregation by sticking between the magnet powder particles, which may lead to a decrease in magnetic properties due to deterioration of the purity and dispersibility of the magnet powder particles.

In the step of preparing the first mixture by mixing the neodymium oxide, boron, and iron, the added transition metal fluoride or chloride may be 2 to 3 types of transition metal fluoride or chloride. In this case, the transition metal fluoride or chloride content may be 0.01 to 0.05 at% based on the total primary mixture. When the content of the transition metal is less than 0.01 at%, improvement of the properties (coercive force, residual magnetic flux density) of a magnet sintered using the synthesized powder cannot be expected. In addition, when the content of the transition metal is 0.05 at % or more, particle aggregation may not be controlled during the synthesis process, and there is a problem in that the properties of a magnet sintered using the synthesized powder may be deteriorated.

Fluorides or chlorides of these transition metals are AlCl ₃ /AlF ₃ , CuCl ₂ /CuF ₂ , GaCl ₃ /GaF ₃ , CoCl ₂ /CoF ₂ , CrCl ₃ /CrF ₃ , NiCl ₂ /NiF ₂ and ZrCl ₄ /ZrF ₄ It may be one or more selected from the group consisting of. Specifically, it may be 2 to 3 selected from the group.

When raw particles of neodymium oxide, boron, iron, two or three kinds of transition metal fluoride or chloride, and calcium react with each other to form a magnet powder, a _{film of NdF 3} or NdOCl may be formed on the surface of the particle, and is formed as a by-product It can control the particle size synthesized with CaO. That is, when metal fluoride or chloride is used, it is easy to control the size of the NdFeB-based powder particles synthesized during the reaction process, and aggregation can also be controlled. In addition, NdF ₃ and the like are coated on the particle surface, and two to three types of transition metals are doped into the NdFeB columnar particles to improve corrosion resistance, coercive force, residual magnetization density, Curie temperature, etc. It is possible to improve physical properties.

Next, iron and calcium are respectively added to the first mixture and mixed to prepare a second mixture. In this case, calcium may be a reducing agent.

Next, the secondary mixture is heated at a temperature of 930 °C to 970 °C for 5 to 15 minutes. This step may be performed for 5 to 15 minutes under an inert gas atmosphere. In general, when the calcium reduction-diffusion method is used to prepare the NdFeB-based particles, the crystalline Nd ₂ Fe ₁₄ B particles are prepared by reacting at a reaction temperature of 900 °C to 1200 °C for 0.5 to 8 hours. However, in this case, there was a problem in that the economic feasibility was lowered because the reaction time was long.

However, in the case of the present invention, at a temperature of 930 ° C to 970 ° C, by heating for 5 minutes to 15 minutes, Nd ₂ Fe ₁₄ B particles can be prepared bar it is economical. The present invention shortens the reaction time by using an exothermic oxidation-reduction reaction of _{Ca serving as a fuel and Nd 2} O ₃ serving as an oxidizer at a temperature of about 950 ° C, and even in a reaction time of 5 to 15 minutes Crystalline NdFeB-based particles can be prepared.

Therefore, it is economical compared to the conventional manufacturing method. Also, the transition metals included in the primary mixture induce particle sintering, thereby reducing the dispersion degree of the magnet powder after manufacturing. However, in the method of manufacturing a magnet powder according to an embodiment of the present invention, such a phenomenon can be suppressed by shortening the reaction time to 5 to 15 minutes. That is, if the heating time is long, there may be a problem that the primary particles of the magnet powder agglomerate, but the present invention prevents this problem by shortening the reaction time.

The magnet powder thus prepared may be _{Nd 2} Fe _{14 B.} In addition, the size of the manufactured magnet powder may be 0.5 μm to 10 μm. In addition, the size of the magnet powder manufactured according to an embodiment may be 0.5 μm to 5 μm.

_{That is, Nd 2} Fe ₁₄ B alloy powder is formed by heating the raw material at a temperature of 930 ° C to 970 ° C. In general, _{in order to form the Nd 2} Fe ₁₄ B alloy powder, the raw material is melted at a high temperature of 1500 °C to 2000 °C and then rapidly cooled to form a raw material mass, and this mass is coarsely pulverized and hydrogenated to crush the Nd _{2 A} Fe ₁₄ B alloy powder is obtained.

However, in the case of this method, a high temperature for melting the raw material is required, and a process of re-cooling and pulverizing it is required, so the process time is long and complicated. In addition, a separate surface treatment process is required to enhance corrosion resistance and electrical resistance of the coarsely pulverized Nd ₂ Fe _{14 B alloy powder.}

The method for producing a magnetic powder by the calcium reduction-diffusion method is to use Ca reduction-diffusion to react at a reaction temperature of 900°C to 1200°C for 1 to 8 hours to _{prepare crystalline Nd 2.} Fe ₁₄ B powder particles, After removing the CaO by-products through washing, a magnet powder is obtained.

However, in the case of manufacturing powder in this way, if a transition metal such as Cu, Al, Ga, or Co is added, magnetic powder particles are synthesized and at the same time particle agglomeration occurs due to sintering, which reduces particle dispersibility and reduces There is a problem in that it has to be crushed using energy.

However, in the case of manufacturing the NdFeB-based powder by the reduction-diffusion method as in this embodiment, Nd _{2 doped with 2 to 3 types of transition metals by reduction and diffusion of raw materials at a temperature of 930 ° C to 970 ° C} Forms Fe ₁₄ B alloy powder. In this step, since the size of the alloy powder is formed in units of several micrometers, a separate grinding process using high energy is not required. More specifically, the size of the magnet powder manufactured in this embodiment may be 0.5 μm to 10 μm. In particular, the size of the alloy powder produced by adjusting the size of the iron powder used as a raw material can be adjusted.

Then, the magnet powder according to an embodiment will be described below. The magnet powder according to the present embodiment can be manufactured at a level of 100 to 200 g within a short time by the above-described manufacturing method. In addition, the magnet powder according to the present embodiment may _{include Nd 2} Fe ₁₄ B doped with 2 to 3 types of transition metals, have a size of 0.5 μm to 10 μm, and a fluoride insulating layer may be coated on the surface. This fluoride may be a fluoride of a transition metal.

Then, a method of manufacturing the magnet powder according to the present disclosure will be described below through specific examples.

Example One: Nd _{2 . 0} Fe ₁₃ BAL _{0 . 05} Cu _{0 . 05} of Produce

32.68 g of Nd ₂ O ₃ , 1.05 g of B, 0.41 g of _{AlF 3 , and 0.65 g of CuCl 2} are placed in a Nalgen bucket and mixed with a paint shaker for 30 minutes. Then, put 70.50 g of Fe here and mix with a paint shaker for 30 minutes, and finally add 17.16 g of Ca and mix for 1 hour with a tubular mixer. Then, compact it into a SUS tube surrounded by carbon sheet and ^{react in an inert gas (Ar, He) atmosphere at 950 o} C for 10 minutes in a tube electric furnace. After the reaction is complete, auto-grind the molded product, add powder to tris-acetic acid buffer or methanol in which ammonium nitrate is dissolved, homogenizer treatment for 10-30 minutes, and ball mill treatment within 30 minutes to 2 hours to remove CaO impurities do. Then, it is washed with acetone and dried. A scanning electron microscope image of the resulting magnet powder is shown in FIG. 1 , an X-ray diffraction pattern is shown in FIG. 2 , and a magnetization history curve is shown in FIG. 3 . As a result, it was confirmed that crystalline Nd-based magnet powder particles doped with Cu and Al having excellent dispersibility and a coercive force of about 3000 Oe were synthesized even when the reaction time was shortened.

Example 2: Nd _{2 . 0} Fe ₁₃ BGa _{0 . 01} Al _{0 . 05} Cu _{0 . 05} of Produce

33.24 g of Nd ₂ O ₃ , 1.04 g of B, 0.40 g of _{AlF 3} , 0.65 g of _{CuCl 2 and 0.12 g of GaF 3} are placed in a Nalgen bucket and mixed with a paint shaker for 30 minutes. Next, put 69.96 g of Fe here, mix for 30 minutes with a paint shaker, and finally add 16.65 g of Ca and mix with a tubular mixer for 1 hour. Then, compact it into a SUS tube surrounded by carbon sheet and ^{react in an inert gas (Ar, He) atmosphere at 950 o} C for 10 minutes in a tube electric furnace. The washing treatment after completion of the reaction is the same as in Example 1. As a result, a scanning electron microscope image of the prepared magnet powder is shown in FIG. 4 , an X-ray diffraction pattern is shown in FIG. 5 , and a magnetization history curve is shown in FIG. 6 . As a result, it was confirmed that crystalline Nd-based magnet powder particles doped with Cu, Al, and Ga having excellent dispersibility and a coercive force of about 3000 Oe were synthesized even when the reaction time was shortened.

comparative example One: Nd _{2 . 3} Fe _{13 . 5} BAL _{0 . 3} Cu _{0 .05} manufacture of

35.84 g of Nd ₂ O ₃ , 1.00 g of B, 0.6 g of _{CaF 2} , 2.33 g of _{AlF 3 , and 0.62 g of CuCl 2} are placed in a Nalgen bucket and mixed with a paint shaker for 30 minutes. Next, put 69.82 g of Fe here and mix with a paint shaker for 30 minutes, and finally add 17.15 g of Ca and mix for 1 hour with a tubular mixer. Then, it is compacted in a SUS tube surrounded by carbon sheet and reacted in an electric tube furnace for 6 hours ^{at 950 o C in an inert gas (Ar, He) atmosphere.} After completion of the reaction, the washing treatment was carried out according to Example 1. A scanning electron microscope image of the resulting magnet powder is shown in FIG. 7 , an X-ray diffraction pattern is shown in FIG. 8 , and a magnetization history curve is shown in FIG. 9 . When the Nd-based magnet powder particles presented in Examples 1 and 2 are compared with the Nd-based magnet powder particles presented in Comparative Example 1, the crystallinity and magnetization history of the powder particles even when the reaction time is shortened from 1-6 hours to 5 minutes to 15 minutes It was confirmed that the curve was maintained at a similar level and the dispersibility was improved.

comparative example 2: Nd _{2 . 3} Fe _{13 . 5} BZr _{0 . 075} Al _{0 .One}

_{Nd 2 O 3 34.99 g, B} 0.98 g, CaF 2 0.6 g, AlF 3 0.76 g, ZrF 4 1.13 g of naljen tube placed in a mixture of 30 minute paint shaker load the next, Fe 68.16 g herein by paint shaker 30 Minute mixing, and finally, add 20.66 g of Ca and mix with a tubular mixer for 1 hour, then compacted in a SUS tube surrounded by carbon sheet, in an inert gas (Ar, He) atmosphere at 950 ^o C for 6 hours in a tube electric furnace. react After completion of the reaction, the washing treatment was carried out according to Example 1. The scanning electron microscope image of the resulting magnet powder is shown in FIG. 9 and the X-ray diffraction pattern is shown in FIG. 10. Nd-based magnet powder particles presented in Examples 1 and 2 and Nd-based magnet powder presented in Comparative Example 1 Comparing the particles, it was confirmed that even when the reaction time was reduced from 1-6 hours to 5 to 15 minutes, the crystallinity of the powder particles was maintained at a similar level and the dispersibility was improved.

As described above, a high temperature is not required compared to the conventional method for manufacturing a magnet powder doped with 2 to 3 types of various transition metals according to the present invention, and the reaction time can be significantly shortened, and a separate grinding process using high energy is performed. It is not required, and the surface treatment process can also be omitted, so it is economical.

Although the preferred embodiment of the present invention has been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

Claims (5)

preparing a first mixture by mixing neodymium oxide, boron, and a fluoride or chloride of a transition metal;
adding and mixing iron and calcium to the first mixture to prepare a second mixture;
Method for producing a magnet powder comprising the step of heating the secondary mixture at a temperature of 930 ° C to 970 ° C, for 5 minutes to 15 minutes. In claim 1,
The prepared magnet powder is Nd ₂ Fe ₁₄ B doped with 2 to 3 types of transition metals. In claim 1,
The content of the fluoride or chloride of the transition metal is 0.01 to 0.05 at% based on the total primary mixture. In claim 3,
The fluoride or chloride of the transition metal is AlCl ₃ /AlF ₃ , CuCl ₂ /CuF ₂ , GaCl ₃ /GaF ₃ , CoCl ₂ /CoF ₂ , CrCl ₃ /CrF ₃ , NiCl ₂ /NiF ₂ and ZrCl ₄ /ZrF _{4 As} A method for producing at least one magnet powder selected from the group consisting of. A magnet powder manufactured by the manufacturing method of any one of claims 1 to 4.

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