KR20150059073A - Method For Preparing R-Fe-B Based Sintered Magnet - Google Patents

Abstract

Disclosed is a method for manufacturing an R-Fe-B based sintered magnet. The main step includes the following. R1-Fe-B-M based sintered magnet is prepared as a main material. A light rare earth element RLO grain layer is arranged on the main material surface. At least one weight rare earth RHX includes metal dysprosium and hydriding dysprosium is arranged on the RLO grain layer. By a heating process in a sintering furnace, the weight rare earth RHX penetrates the RLO grain layer, is evaporated to the main material surface, and is diffused from the surface into the magnet. The RLO grain layer becomes the transfer medium and does not react with the weight rare earth element in a total process. The light rare earth element oxide and fluoride RLO grain layer are arranged between the weight rare earth RHX in the magnet so that the direct contact of the magnet and the weight rare earth RHX can be prevented. Meanwhile, magnet surface deposition due to the excess of the weight rare earth RHX vapor can be prevented by preventing the diffusion process of the weight rare earth RHX vapor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a method of manufacturing a sintered magnetic body of R-Fe-

The present invention relates to a method for producing a sintered magnet of the R-Fe-B type, and relates to a rare earth permanent magnet material region.

The demand for energy-saving motors in the automobile and electronic fields is gradually increasing, and the R-Fe-B type rare earth permanent magnet market is being applied more and more. In order to increase the coercive force, a large amount of heavy rare earth elements must be used, so that the cost of the magnetic material rapidly increases. Therefore, reducing the use of heavy rare earth elements is also an important research task in the rare earth permanent magnet region. Through the analysis of magnetic microstructure, it was confirmed that the rare earth element diffusion method in the grain boundaries was confirmed, and the grain boundary line scattering field was reduced and the magnetic exchange coupling effect was weakened effectively to harden the grain boundary magnetism and to prevent the magnetic remanence Coercivity can be greatly increased. By increasing the performance of the magnetic body through such a method, the cost of the magnetic body can be effectively reduced.

As a result of the various methods according to the prior art, the grain boundary diffusion effect has been reached, and the grain boundary diffusion effect can be roughly classified into two kinds: one is the contact method, the heavy rare earth element is disposed on the surface of the magnetic body, And the grain boundary diffusion is realized in such a manner that the rare earth element penetrates along the crystal grain boundaries (see Patent Document 1 and Patent Document 2). The other is a vacuum evaporation method which causes the heavy rare earth element to form a vapor through the heating system and slowly diffuse into the magnetic body. (See Patent Document 3 and Patent Document 4). Both methods can achieve grain boundary diffusion effect, but contact method easily causes defects of magnetic body surface condition in actual production process. Now, after processing magnetic body by applying contact method and continuing to machining method, defects of magnetic body surface . The thickness that can be treated at present to apply the contact method is best when the piece is smaller than 7mm. Such a magnetic body is small in size, and its workload is large during the machining process, and the contact method causes an unbalance of the diffusion process because the rare earth element can not make complete contact with the magnetic body. On the other hand, a large concentration difference is formed in a portion directly in contact with the heavy rare earth element to form a large driving force on the surface of the magnetic body so that the heavy rare earth element can not be completely diffused along the grain boundary, and a rare earth element enters the main phase, In addition to causing the residual magnetism to drop, in some cases, the high Dy layer on the surface of the magnetic body must be polished during the actual production process, resulting in waste of the magnetic material. The vacuum evaporation method isolates the magnetic body and the heavy rare earth element using a pedestal, etc., and causes the heavy rare earth element to form the steam through heating, and then the steam spreads to the vicinity of the magnetic body and slowly diffuses into the magnetic body. When such a method is applied, it is necessary to prevent the direct contact between the magnetic substance and the heavy rare earth element by forming a support with a material which does not readily evaporate even at high temperature in the furnace, so that the supporting installation process is complicated during the actual operation, In addition to greatly increasing the degree of difficulty, the raw material frame occupies a very large space, greatly reducing the amount of raw material input, and in order to maintain the cleanliness of the evaporation environment, the support frame is generally made of a material having a low saturated vapor pressure, . It is difficult to control the evaporation concentration of the evaporation method. If the temperature is too low, the heavy rare earth vapor will hardly enter the magnetic body through the surface of the magnetic body, and the treatment time will increase drastically. If the temperature is too high, It becomes much more than the magnetism vapor, and it becomes difficult to form a heavy rare earth element layer on the surface of the magnetic body, and the grain boundary diffusion effect can not be attained. The above background arts are all cited in the following patent documents.

Patent Document 1: CN100565719C 2006.2.28

Patent Document 2: CN101404195B Nov. 16, 2007

Patent Document 3: CN101651038B 2007.3.01

Patent Document 4: CN101375352A 2007.1.12

In order to solve the existing technical problems, the present invention provides a method for manufacturing a sintered magnet of R-Fe-B type. Wherein at least one RLO granular layer of at least one of oxides and lanthanum oxides of lanthanum, cerium, neodymium, praseodymium and fluoride is disposed between the magnetic body and the heavy rare earth rhodium, wherein the heavy rare earth rhodium is at least one of metal dysprosium and dysprosium hydride. On the other hand, the RLO granular layer prevents the direct contact of the magnetic and heavy rare earth elements, and on the other hand, the RLO granular layer lowers the free process of heavy rare earth vapor and does not evaporate directly on the magnetic body surface, So that the residual magnetism of the magnetic body is lowered. By using the heat treatment, it is possible to diffuse to the surface of the magnetic body through the RLO granular layer using the heavy rare earth element, and to penetrate into the magnetic body along the grain boundaries.

In order to solve the above-described technical problem, the present invention provides a method for producing a sintered magnet of R-Fe-B type, including:

A kind of R-Fe-B sintered magnet manufacturing method includes the following:

1) R ₁ -Fe-BM sintered magnet is manufactured. R ₁ is a double rare earth elements Nd, Pr, Tb, Dy, La, Gd, Ho selecting at least one or more elements selected from and R ₁ The content is 27 ~ 34wt%. The B content is 0.8 to 1.3 wt%. M is selected from one or more elements selected from Ti, V, Cr, Mn, Co, Ga, Cu, Si, Al, Zr, Nb, W and Mo; the content is 0 to 5 wt%;

2) After applying an acid solution to the sintered magnet body in order, washing with ion-removing water and drying treatment, a subject magnetic body is obtained.

3) Arrange the RLO granular layer on the surface of the treated magnetic body and place the heavy rare earth RHX layer on the RLO granular layer. The RLO granules are lanthanum, cerium, neodymium, praseodymium oxide and at least one granule of a fluoride or a mixture thereof. The RLO granule particle size is 0.1 to 3 mm and the RLO granule layer thickness is 0.1 to 15 mm. The heavy rare earths RHX is at least one of metal dysprosium and dysprosium hydride. The treated magnetic body, the RLO granular layer and the heavy rare earth RHX layer form a processing unit.

4) Put the to-be-treated unit described in 3) above into a raw material container and heat treatment under vacuum or inert gas protection conditions, the sintering temperature is 970 ° C at the maximum, and the sintering time is 0.5 to 48 hours. After the temperature is kept at the maximum temperature, the magnetic material is subjected to aging treatment at an aging temperature in the range of 430 to 650 ° C. and an aging time of 2 to 10 hours.

Fe is iron and B is boron. R ₁ -Fe-BM sintered magnet is obtained by processing in R ₁ -Fe-BM alloy, and R ₁ , M is a component of alloy, and any one or more of all open elements can be selected. The above-described untreated unit can be stacked until it is filled in the raw material container.

The characteristic feature of the present invention is to prevent the direct contact by isolating the magnetic and heavy rare earth compounds by making the oxide and the fluoride granular RLO of Kyunghee soil element as a transmission medium and preventing it from reacting with the heavy rare earth element, Is slowly diffused to the surface of the magnetic body, the heavy rare-earth vapor concentration is too high and the RLO granule price is low, so that it is only required to spread on the surface of the magnetic body directly in the production process. By controlling the thickness and granule size of the RLO granulation layer, it is possible to control the medium rare-earth RHX diffusion concentration and to reduce the medium rare-earth rhX and magnetic spacing to improve the feed rate.

Preferably, inert gas is injected in the step 4) to maintain the pressure, and the maintaining pressure may be 0.01 to 20 KPa.

The method of applying the inert gas temperature maintenance method in the highest temperature zone is based on setting the temperature low to prevent the vapor concentration from becoming too high when the RLO granular layer is thin. However, if the temperature is low, the entire diffusion process cycle is greatly delayed. On the other hand, by applying RLO granule layer thickness and temperature increase method, it is possible to lower the amount of raw material injection and by delaying evaporation process of heavy rare earth RHX through inert gas pressure holding method in high temperature region, It is possible to increase the input amount and speed up the processing cycle.

Preferably, the above-mentioned RLO granule particle size is 0.3 to 0.8 mm, and the RLO granule may be a gypsum earth oxide having a low saturated vapor pressure.

The RLO granule particle size should be 0.3-0.8 mm in order to prevent excessive transmission or excessive obstruction to RHX vapors in the RLO granules. In order to reduce the effect of RLO granulation on the atmosphere quickly, RLO granules preferentially select low-saturation oxides.

Preferably, the thickness of the to-be-processed magnetic body described in step 3) may be 1 to 7 mm.

In the heat treatment process, the heavy rare earth rhodium (RHX) diffuses into the magnetic body through the liquid crystal grain, and the diffusion process mainly has the differential driving force. Therefore, if the difference between the heavy rare earth element and the columnar phase on the grain boundary is too large, Resulting in a distinct drop of the magnetic body Br. In the process, the steam concentration should be controlled by adjusting the temperature, magnetic and heavy rare-element intervals, and so on. If the driving force is not large due to the low concentration difference, the diffusion process becomes very gentle. If the thickness of the magnetic body is 7 mm or more, it is difficult to realize the complete diffusion, resulting in variation in the performance of the magnetic body.

Preferably, the heavy rare earth RHX forms described above may be in powder, granular or plate form. Most preferably, the dual RHX form is plate-like.

On the other hand, the present invention not only realizes non-direct contact between a magnetic material and heavy rare earth rhodium oxide (RHX) by arranging an oxide earth element oxide and a fluoride RLO granular layer between heavy rare earths RHX in a magnetic body, It is possible to prevent the evaporation of the magnetic body surface due to the excessive amount of heavy rare earth RHX vapor. In general, the RLO granule is used as a transmission medium to avoid reacting with heavy rare earth elements. In addition, since the RLO granule price is low, the cost can be saved and the raw material injection time can be shortened can do. By injecting inert gas at a constant pressure through the pressure maintenance during the heat treatment process, it is possible to control the heavy rare-earth RHX vapor concentration and to shorten the distance between the rare-earth RHX and the magnetic body, thereby improving the feed amount.

1 is a cross-sectional view for explaining an arrangement method during a heat treatment process.
2 is a plan view for explaining an arrangement method during a heat treatment process.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

(Example 1)

A vacuum refining furnace is applied to refine the constituent raw materials under the protection of an inert gas to form a scale having a thickness of 0.1 to 0.5 mm. The obtained R-Fe-B alloy scale gold grain boundary system becomes clear. The alloy scale crushes the SMD to a size of 3.4 μm through mechanical grinding, hydrogen explosion and jet milling. Compacted in the direction of the magnetic field of 15KOe to obtain a compact density of 3.95 g / cm < ^{3 &} gt ;. The compact is sintered in a sintering furnace at a temperature of 1080 ° C. for 330 minutes and then aged at 480 ° C. for 240 minutes. The aging treatment is carried out by dissolving the alloy components and then subjecting the components to a cryogenic deformation or casting, And the size of the magnet is 40 mm * 30 mm. The size of the magnet is 40 mm * 30 mm. The size of the magnet is 40 mm * 30 mm * 2.4 mm, tolerance: ± 0.03 mm.

The magnet piece is subjected to an acid solution, an ion-removing water surface cleaning and a drying treatment to obtain the target magnetic material M1 and M1. First, a layer of mixed granules of neodymium oxide, praseodymium oxide and cerium oxide is placed in the bottom of the raw material container, the mass ratio thereof is 7: 2: 1, the granule particle size is 0.1-0.5 mm, and the thickness is 0.8 mm. Subsequently, a heavy rare earth element Dy plate is placed on the mixed granules, and the Dy plate thickness is about 1 mm and the purity is 99.9% or more. After placing the Dy plate, the other mixed granules are placed on the Dy plate. The thickness of the mixed granules is about 0.8 mm, and the magnetic material is placed on the mixed granules. The magnetic material is parallel to the bottom of the raw material container and the gap between the magnetic material and the magnetic material The spacing is about 2 mm. After the magnetic body is placed, another mixed granule is placed on the magnetic body, the Dy plate is placed on the mixed granule, and the process of arranging the mixed granule, the magnetic body, the mixed granule and the Dy plate is repeated until the maximum capacity of the raw material container is reached (See FIG. 1 and FIG. 2).

The raw material container is put into the heat treatment apparatus and the temperature rising process is set: 50 to 650 ° C * 100 minutes + 650 ° C * 120 minutes + 650 to 830 ° C * 30 minutes + 830 ° C * 18 hours + Apply argon temperature maintenance at 830 ° C warming and set the furnace pressure to 2.1Pa. After the quench-bonding, the temperature is raised to 480 캜, aged for 4 hours, and quenched to room temperature to obtain the magnetic material M2.

Performance comparison between magnetic material M2 and magnetic material M1 to be treated before diffusion Item density Br Hcj (BH) max Hk / Hcj unit (g / cm ³⁾ kGs kOe MGOe - M2 7.56 13.97 18.21 46.85 0.96 M1 7.56 14.06 13.46 47.09 0.97

Comparison of main components of magnetic substance M2 and M1 to be treated before diffusion treatment Analysis item B Al Co RE Dy Pr Nd M2 Survey value% 0.97 0.1 0.89 31.21 0.85 4.71 25.65 M1 Survey value% 0.97 0.1 0.9 30.91 0.52 4.72 25.67

Table 1 and Table 2 show that when this method is applied, M2 is lowered to about 90 Gs in residual magnetic Br, and Hcj is increased by about 4.75 KOe compared to M1. From the analytical measurements, it can be seen that Dy is increased by about 0.33 wt% compared to M1.

(Example 2)

A vacuum refining furnace is applied to refine the constituent materials under the protection of an inert gas to form a scale having a thickness of 0.1 to 0.5 mm. The obtained R-Fe-B alloy scale gold grain boundary becomes clear. The alloy scale is HD and jet milled. The size of the powdered SMD is broken down to 3.2 μm, the jet milled powder is mixed, and compacted in a magnetic field direction of 15 KOe to obtain a compact. The compact density is 3.95 g / cm ³ . The compact is vacuum sintered in a sintering furnace and sintered at a temperature of 1090 ° C for 330 minutes. Next, aging is carried out at an aging temperature of 480 캜 for 240 minutes to obtain green. The green is cut through a double line to obtain a magnet piece of the final product size, and the size of the magnet piece is 40 mm * 30 mm * 2.4 mm and the tolerance is ± 0.03 mm.

The magnet pieces are subjected to an acid solution, an ion-removing water surface cleaning and a drying treatment to obtain the subject magnetic materials M3 and M3. In order to prevent adhesion due to direct contact between the magnetic substance and the heavy rare earth element, a layer of neodymium oxide granules having a thickness of about 1 mm is placed at the bottom of the raw material container, and the particle diameter range is set to 0.3 to 1 mm. Next, heavy rare earth Dy granules and DyH ₃ on neodymium oxide granules Placing the mixture granulated (that has already been evenly mixed) and D y of the granules and granules DyH ₃ granules particle size is from 1 to 3mm into the range and dysprosium granules and granules DyH ₃ mass ratio is 1: 1. Place the Dy granules and DyH ₃ granules and place a layer of neodymium oxide granules thereon with a thickness of about 1 mm. Next, place the magnetic substance on the neodymium oxide granules. The magnetic substance should be balanced with the bottom of the raw material container, and the gap between the magnetic substance and the magnetic substance should be uniformly spaced to about 2 mm. After the magnetic body is placed, another layer of neodymium oxide granules is placed on the magnetic body, and mixed granules of rare earth Dy granules and DH ₃ granules are placed on the neodymium oxide granules. Then, the neodymium oxide granules, , Neodymium oxide granules, Dy granules and DyH ₃ Mix granules of granules.

After the raw material container is put into the heat treatment apparatus, the temperature rising process is set: 50 to 650 ° C * 100 minutes + 650 ° C * 120 minutes + 650 to 810 ° C * 30 minutes + 810 ° C * 18 hours + The furnace pressure is maintained at 2.0 Pa by applying argon temperature maintenance at 810 ℃. After the quench-bonding, the temperature is raised to 480 DEG C and aging treatment is performed for 4 hours, followed by quenching to room temperature to obtain magnetic material M4.

Performance comparison between magnetic substance M4 and magnetic substance M3 to be treated before diffusion treatment Item density Br Hcj (BH) max Hk / Hcj unit (g / cm ³⁾ kGs kOe MGOe - M4 7.56 13.94 18.76 46.15 0.95 M3 7.56 14.06 13.46 47.09 0.97

Comparison of main components of magnetic substance M4 and magnetic substance M3 to be treated before diffusion treatment Analysis item B Al Co RE Dy Pr Nd M4 survey value% 0.97 0.1 0.89 31.24 0.89 4.72 25.63 M3 survey value% 0.97 0.1 0.9 30.91 0.52 4.72 25.67

Table 3 and Table 4 show that when this method is applied, the residual magnetic Br of M4 is lowered by about 120 Gs and the Hcj is increased by about 5.3 KOe compared to M3. From the analytical measurements, it can be seen that M3 increases Dy by about 0.37 wt% compared to M4. The analysis shows that the Dy granules applied to the present invention as compared to Example 1 are irregular in shape of the Dy granules in the medium rare earth source and form a high Dy vapor temperature due to the surface effect and the like at the initial stage of the heat treatment and as a result, Can be found.

(Example 3)

A vacuum refining furnace is applied to refine the constituent materials under the protection of an inert gas to form a scale having a thickness of 0.1 to 0.5 mm. The obtained R-Fe-B alloy scale gold grain boundary becomes clear.

The alloy scale is crushed by HD and jet milling to 3.2 μm in size of the powder SMD, mixed with the jet mill powder, compacted in a magnetic field direction of 15 KOe to obtain a compact density of 3.95 g / cm ³ . Vacuum sintering is performed in a sintering furnace and sintered at a temperature of 1085 ° C for 300 minutes. Next, aging is performed at 490 ° C for 240 minutes to obtain green. The green is obtained by cutting a double piece to obtain a magnet piece of the final product size. The magnet size is 50 mm * 15 mm * 6 mm and the tolerance is ± 0.3 mm.

The magnet piece is subjected to an acid solution, an ion-removing water surface cleaning and a drying treatment to obtain the target magnetic material M5. In order to prevent the magnetic substance and the heavy rare earth element from coming into direct contact with each other, a layer of neodymium oxide and praseodymium oxide mixed granules is disposed at the bottom of the raw material container, the granule size is within the range of 0.15 to 0.3 mm and the thickness is about 1.2 mm do. Next, a heavy rare earth element Dy granule is placed on the neodymium oxide and praseodymium oxide granules, and the granule size is within the range of 0.5 to 1.2 mm. After placing the granules, place one layer of mixed granules of neodymium oxide and praseodymium oxide on the granules with a thickness of about 1.2 mm. Next, the magnetic substance is placed on the mixture granules of neodymium oxide and praseodymium oxide. The magnetic substance is parallel to the bottom of the raw material container, and the gap between the magnetic substance and the magnetic substance is set to be about 2 mm. After the magnetic body is placed, another layer of neodymium oxide and praseodymium oxide granules is placed on the magnetic body, and the Dy granules are placed on the neodymium oxide and praseodymium oxide granules. Next, neodymium oxide, praseodymium oxide granules, magnetic material, neodymium oxide and praseodymium oxide granules, and Dy granules are arranged in sequence until the maximum capacity of the raw material container is reached.

After the raw material container is put into the heat treatment apparatus, the temperature rising process is set: 50 to 650 ° C * 100min + 650 ° C * 120min + 650 to 830 ° C * 30min + 830 ° C * 30h + Vacuum sintering is applied at 830 ℃, quenching is carried out after quenching, temperature is raised to 500 ℃, aging treatment is performed for 4 hours and quenched to room temperature to obtain magnetic material M6.

Performance comparison between magnetic substance M6 and magnetic substance M5 to be treated before diffusion treatment Item density Br Hcj (BH) max Hk / Hcj unit (g / cm ³⁾ kGs kOe MGOe - M6 7.58 14.17 21.12 47.87 0.95 M5 7.57 14.31 15.42 48.73 0.99

Magnetic substance M6 and magnetic substance to be treated M5 before diffusion treatment Analysis item B Al Co RE Dy Tb Pr Nd M6 survey value% 0.98 0.1 0.6 29.82 1.08 0.5 5.87 22.37 M5 survey value% 0.99 0.1 0.6 29.48 0.70 0.5 5.88 22.40

Table 5 and Table 6 show that M6 has lower residual magnetic Br of about 140Gs and Hcj of about 5.7KOe compared to M5. From the measurement of the components, it can be seen that M6 is increased by about 0.38 wt% compared to M5. Since the magnetic body is thick, the processing time of this embodiment is relatively long.

What has been described above is not used to limit the present invention merely as a comparatively preferred embodiment of the present invention. Accordingly, all changes, equivalents, and improvements within the spirit and scope of the present invention should be covered by the scope of the present invention.

1: RLO Granular layer 2: Dy plate
3: sintered magnetic body 4: sintered magnetic body
5: RLO granular layer

Claims (5)

A method for producing a sintered magnetic body of R-Fe-B type,
1) producing a R ₁ -Fe-BM sintered magnet,
Among these, R ₁ is at least one selected from rare earth elements Nd, Pr, Tb, Dy, La, Gd and Ho, or a combination thereof, and R ₁ The content is 27 ~ 34wt%. B content is 0.8 to 1.3 wt%
M is at least one selected from the group consisting of Ti, V, Cr, Mn, Co, Ga, Cu, Si, Al, Zr, Nb, W and Mo or a combination thereof and the content is 0 to 5 wt% ,
2) The sintered magnet body of the step 1) is obtained by subjecting a treated magnetic body to an acid solution, washing with ion-removing water, and drying treatment;
3) disposing an RLO granular layer on the surface of the to-be-treated magnetic body and placing a heavy rare earth layer on the RLO granular layer,
Wherein the RLO granules are at least one granule selected from oxides and fluorides of lanthanum, cerium, neodymium and praseodymium, or a combination thereof,
The RLO granule particle size is 0.1 to 3 mm, the RLO granule layer thickness is 0.1 to 15 mm,
Wherein said heavy rare earths RHX is at least one of metal dysprosium, dysprosium hydride,
The treated magnetic body, the RLO granular layer and the heavy rare earth RHX layer form a to-be-treated unit,
4) a step of heat treating and sintering the material to be treated in the step 3) in a raw material container under the condition that it is protected by a vacuum or an inert gas,
The sintering temperature is in the range of 430 to 650 ° C. and the aging time is 2 to 10 hours. The sintering temperature is in the range of 430 to 650 ° C., and the sintering temperature is in the range of 2 to 10 hours Of the R-Fe-B sintered magnet body. The method according to claim 1,
The method for manufacturing a sintered magnet of R-Fe-B type according to claim 4, wherein the inert gas is injected in the step of maintaining the maximum temperature of the step (4) to maintain the pressure while the maintaining pressure is 0.01 to 20 KPa. The method according to claim 1,
Wherein the RLO granules have a grain size of 0.1 to 3 mm and the RLO granules have a low saturation vapor pressure. The method according to claim 1,
The method for manufacturing a sintered magnet of R-Fe-B type according to claim 3, wherein the to-be-processed magnetic body has a thickness of 1 to 7 mm. 5. The method according to any one of claims 1 to 4,
The method for producing a sintered magnet of R-Fe-B type according to claim 1, wherein the heavy rare earth rhodium (RHX) phase is powder, granular or plate-like.

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