JP2015113525A - Method for preparing high coercive force magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing a high coercive force magnet, capable of optimizing a process of containing a heavy rare earth powder in a permanent magnet using a jet mill without ejecting an ultrafine powder to improve production efficiency and reduce cost.SOLUTION: A method for preparing a high coercive force magnet comprises the steps of: 1) mixing a R-Fe-B-M alloy powder with a heavy rare earth powder Ror a heavy rare earth powder RX; 2) polishing the mixed powder by a new jet mill 8; 3) mixing and pressing the polished magnetic powder into a block to be preliminarily sintered; 4) performing autoclave treatment; and 5) obtaining a high coercive force magnet by aging treatment. The collection of an ultrafine powder by a filter 14 is achieved when the magnetic powder including the R-Fe-B-M alloy powder and the heavy rare earth is simultaneously polished by the new jet mill improved not so as to eject an ultrafine powder.

Description

  The present invention relates to a method for preparing a high coercive force magnet.

  Since its advent, sintered permanent magnet materials have been widely used in many fields such as electronics, energy, communication, and machinery due to their excellent magnetism and rich resources. Since recent years, permanent magnet materials have been increasingly used in the automotive field, but there are significant weaknesses. One of them is that the thermal stability is poor and the magnetic flux is easily lost at high temperatures. The improvement of the thermal stability is realized mainly by obtaining a higher coercive force. Recently, methods for improving the coercive force of magnets are mainly grain boundary diffusion and dual alloying.

  According to the “Preparation Method of Sintering Neodymium Permanent Magnets with Heavy Rare Earth Hydride Nanoparticles” published in China Patent Publication Number CN101521069, NdFeB powder with accelerated tip technology, hydrogen explosion and jet mill, terbium with PVD method Prepare nano powder of hydride or DY compound, mix two kinds of powder, orient by magnetic field, perform press molding, dehydrogenate, sinter and age the block to make sintered magnet get. This method obtains a higher coercivity with a small amount of heavy rare earth dysprosium or terbium. However, since this method uses the PVD method for DY compounds or terbium hydrides, the investment in equipment is high, the cost is high, and the output of DY compounds or terbium hydrides is low. Therefore, it cannot be mixed uniformly.

  According to `` REARE EARTH MAGNET AND METHOD FOR MANUFACTURING '' published in US Patent Publication No. US649765, when pulverizing alloys with conventional jet mill equipment, ultrafine powder with a particle size of 1.0 μm or less is removed, and the quantity ratio of ultrafine powder is Adjust to less than 10% of total powder. In the case where heavy rare earth is introduced with the conventional jet mill equipment, the heavy rare earth is partially discharged as ultra fine powder, so that it is not useful for sufficient utilization of the heavy rare earth element.

  According to the “optimized processing method for preparing a permanent magnet with high coercivity by putting heavy rare earth hydride in neodymium” published in China Patent Publication Number CN102368439, hydrogen explosion of heavy rare earth R is performed and ball mill grinding or jet Obtain fine powder of heavy rare earth hydride by mill polishing, treat NdFeB alloy by hydrogen explosion, obtain NdFeB fine powder by ball milling or jet mill treatment, mix two kinds of fine powder, magnetize, mold Press to obtain a block, sinter the block at 1000 to 1050 ° C., and perform aging treatment at 580 to 700 ° C. to obtain a magnet. However, this method has a sintering temperature of 1000 to 1050 ° C. At this temperature, the heavy rare earth diffuses significantly from the crystal boundary to the main phase, which has a significant effect on the improvement of the coercive force. At the same time, in this method, when the heavy rare earth hydride is polished by a jet mill, the hydride is easily discharged as ultrafine powder, which leads to the waste of the heavy rare earth element.

The People's Republic of China JP101521069 United States Patent Publication No. US649765 The People's Republic of China JP102368439

An object of the present invention is to provide a method for preparing a high coercive force magnet. In this method, a new jet mill that does not discharge improved ultrafine powder is simultaneously subjected to polishing treatment for R ¹ -Fe-BM alloy powder and powder containing heavy rare earth, and the magnetic powder is polished with the new jet mill. In addition to realizing the recovery of ultrafine powder by using a jet mill, there is a problem that a part of heavy rare earth is discharged by a jet mill and a problem that it is not uniform when mixing two magnetic powders with different particle sizes by a mixer It solves at the same time. The present invention is capable of preparing a permanent magnet with high coercive force and high remanence by optimizing the process of putting heavy rare earth into the permanent magnet due to the characteristics of the jet mill that does not discharge ultra fine powder, leading to improvement in production efficiency and cost reduction. With the goal.

  In the present invention, a solution for explaining the above problem is as follows. That is, the present invention is a method for preparing a high coercive force magnet including the following steps.

1) Stop zone-R ¹ -Fe-BM alloy powder is obtained by hydrogen explosion, R ¹ -Fe-BM alloy powder is R ¹ -Fe-BM alloy powder is heavy rare earth powder R ² or heavy rare earth powder Put R ² X and mix to get mixed powder. Among them, R ¹ is ^one of rare earth elements, the content of R ¹ is 26 wt% <R ¹ <35 wt%, the B content is 0.8 wt% to 1.3 wt%, M is Ti, V, Cr, Mn, One or more of Co, Ga, Cu, Si, Al, Zr, Nb, W, and Mo, the content of M is 5 wt% or less, the remaining is iron and inevitable foreign matter, R ² is at least one of Dy, Tb and Ho, X is at least one of O, H and F, R ² or R ² X is 0.1 wt% of the total weight of the R ¹ -Fe-BM alloy powder Occupies ~ 1.5wt%.

  2) Polish the mixed powder with a new jet mill to obtain magnetic powder. The average particle size of the magnetic powder is controlled to 1 to 10 μm.

  3) Add 0.1-0.3wt% fatty acid ester to the magnetic powder polished in 2), mix for 0.1-3h, and push the magnetic powder into the block. The block is pre-sintered in a vacuum autoclave furnace without applying pressure.

4) After completing the pre-sintering treatment, autoclave treatment is performed by applying pressure to obtain a magnet material having a density of 7.3 g / cm ³ or more.

  5) In 4), the magnet material after autoclaving is subjected to aging treatment to obtain a high coercivity magnet.

  Based on the above solution, the present invention can also be improved as follows.

  Furthermore, in 3), the temperature of the pre-sintering treatment is ≦ 950 ° C. and time ≧ 60 min.

  Furthermore, in 4), the autoclave temperature is 700 to 1000 ° C., the pressure is 30 to 150 MPa, and the time is 2 to 30 min.

  Further, in 5), the aging treatment condition is that the treatment is performed at 400 to 600 ° C. for 3 to 6 hours.

  1. Cost can be reduced. Heavy rare earth element resources are finite and expensive, but in the case of conventional jet mill polishing, they are easily crushed and finally discharged partially as ultrafine powder. This is a waste of heavy rare earth elements. Polishing two types of powders with a jet mill that does not discharge ultrafine powders can more effectively reduce the amount of heavy rare earth elements used, and at the same time, obtain a permanent magnet with high coercivity and high remanence.

  2. The present invention can solve the problem of mixing powders having different particle sizes at the same time during jet mill polishing. In the conventional method, a mixing process is performed by a mixer, but two kinds of powders having different particle diameters (especially when any one of them is too fine) cannot be mixed uniformly. This method can improve the production efficiency and at the same time solve the problem of being unable to mix uniformly.

  The present invention includes a loading system, a polishing system, a process gas compression / circulation system, and a material recovery system, wherein the polishing system is connected to the loading system, and each of the process gas compression / circulation systems includes the polishing system, Process gas is introduced into the loading system and the material recovery system, and the material recovery system includes a cyclone, an ultrafine filter, a fine and ultrafine recovery mixing chamber, and a recovery tank, and the cyclone inlet end and the cyclone Connected to the outlet end of the polishing system, the cyclone has two outlet ends, the outlet end No. 1 is the ultra fine filter, the outlet end No. 2 is the recovery mixing chamber, The outlet end of the fine powder filter is connected to the fine powder and ultra fine powder collection and mixing chamber. The fine and ultra fine powder collection and mixing chamber includes a mixing chamber body and a valve at the outlet thereof, and the outlet end of the mixing chamber body is connected to the collection tank by the valve. A jet mill apparatus for preparing a high coercive force magnet is provided.

  Based on the above solution, the present invention can also be improved as follows.

  Further, the loading system includes an upper tank, a silo and a vibration loader connected in sequence, and there are loading interface gas switching valves on both sides of the place where the upper tank and the silo are connected, and the process gas The outlet end of the compression circulation system is connected to the loading interface gas switching valve, the process gas compression circulation system puts process gas into the silo by the loading interface gas switching valve, Connected at the upper end to the bottom of the silo and connected at the lower end to the polishing system to transport the material to the polishing system.

  Further, the polishing system includes a polishing chamber and a classifier and a load cell installed in the polishing chamber in order, a classifier motor on the classifier side, and the cyclone of the cyclone through a pipe line on the opposite side. Connected to the inlet end.

  Further, the vibrator is a pneumatic vibrator or an electromagnetic vibrator.

  Further, the recovery tank has a sealed configuration, and interface gas switching valves are provided on both sides of a location where the recovery tank and the mixing chamber main body are connected, and the process gas compression and circulation system includes the interface gas. Process gas is introduced by a switching valve.

  Further, the process gas is any one or a mixture of nitrogen, argon, helium.

  In addition, there are vibrators on both sides of the mixing chamber body.

  Furthermore, the outlet end No. 2 of the cyclone is connected to the recovery and mixing chamber by a double flap valve.

  Furthermore, the outlet end of the ultrafine powder filter is connected to the fine and ultrafine powder collecting and mixing chamber by a double flap valve.

  In the present invention, the improved jet mill apparatus utilizes a lossless recovery configuration of fine powder and ultrafine powder in the material recovery system, and the ultrafine powder recovered by the fine powder filter and the powder recovered by the cyclone are fine powder and ultrafine powder. It enters the lossless recovery and mixing chamber and is vibrated by a vibrator to perform initial mixing and recovery. Since the fine powder recovery rate is 99.9% or more, ultra fine powder is not generated by the discarded filter, which not only reduces the amount of rare earth used and improves the material recovery rate, but also processes the filtered ultra fine powder. Is not necessary, making production easier and improving safety.

The block diagram of the jet mill apparatus improved by this invention. The principle figure of the conventional jet mill apparatus. The principle figure of the novel jet mill apparatus improved by this invention.

  The principles and features of the present invention will now be described, examples being used only to illustrate the present invention and not to limit the scope of the invention.

  As shown in FIG. 1, the jet mill apparatus of this embodiment includes a loading system, a polishing system, a process gas compression / circulation system, and a material recovery system. The loading system includes an upper tank 1, a silo 2 and a vibration loader 3 that are connected in order, and a loading interface gas switching valve 4 on both sides of the place where the upper tank 1 and the silo 2 are connected. The exit end of the process gas compression / circulation system is connected to the loading interface gas switching valve 4, the process gas is introduced into the silo 2 by the loading interface gas switching valve 4, and the vibration loader 3 is connected to the silo 2 at the upper end. The vibration loader 3 is connected to the polishing chamber 8 of the polishing system at the lower end, the material is transported to the polishing system, and the polishing system is installed in the polishing chamber 8 and the polishing chamber in order. Classifier 6 and load cell 7, and the polishing chamber 8 is at the bottom Connected to the outlet end of the process gas compression / circulation system, the process gas compression / circulation system puts the process gas into the polishing chamber, the classifier 6 has the classifier motor 5, and the other side is the material recovery by the pipe line Connected to the inlet end of the system cyclone 15. The compressor 17 is connected to the polishing chamber 8 and the ultrafine filter 14.

  The raw material recovery system includes a cyclone 15, an ultrafine powder filter 14, a fine and ultrafine powder collection and mixing chamber 12, and a recovery tank 9, and an inlet end of the cyclone 15 is connected to an outlet end of the polishing system. 15 has two outlet ends, outlet end No. 1 15.1 is connected to the ultra fine filter 14 and outlet end No. 2 15.2 is connected to the recovery mixing chamber 12 by the double flap valve 13 And the outlet end of the ultrafine powder filter 14 is connected to the fine powder and ultrafine powder recovery mixing chamber 12 by a double flap valve 13, and the fine powder and ultrafine powder recovery mixing chamber 12 is a mixing chamber. A main body and a valve 16 at the outlet thereof, the outlet end of the mixing chamber main body being connected to the recovery tank 9 by the outlet valve 16, and the mixing chamber On both sides of the body there is a vibrator 11. The selected vibrator 11 is a pneumatic vibrator or an electromagnetic vibrator. In this embodiment, the ultrafine powder collected by the ultrafine filter and the powder collected by the cyclone enter the lossless collection and mixing chamber of the fine powder and ultrafine powder, and are vibrated by the vibrator to perform the initial mixing and recovery.

  The selected recovery tank 9 of the present embodiment has a sealed configuration, and there are interface gas switching valves 10 on both sides of the portion connected to the mixing chamber 12, and the process gas compression and circulation system is connected to the interface gas. Process gas is introduced into the recovery tank 9 by the switching valve 10.

  In this example, the process gas used in the powder production apparatus is an inert gas, the oxygen content is 50 ppm or less, the selected one is 200 ppm, and one or more of nitrogen, argon, helium Contains a mixture.

  Next, the effect of the jet mill apparatus improved by the present invention by a specific contrast test will be described.

Select raw materials with a purity of 99 wt% or more, perform ball blasting for 10-60 min, prepare with weight percent Nd ₂₂ Dy _8.8 Co _2.0 Cu _0.15 Ga _0.1 Al _0.2 Ti _0.1 B _0.97 Fe _65.68 , vacuum strip When the raw material prepared in the casting furnace is melted and the temperature of the combined financial liquid reaches 1470 ° C, the fin is cast and forcibly cooled to 150 min, and the master alloy fin of the rare earth permanent magnet material with a thickness of 0.2 to 0.5 mm is get.

  Put the rare earth permanent magnet material master alloy into a hydrogen crushing furnace, fully vacuum, then add hydrogen gas of 80-90KPa, suck up hydrogen gas to 120min, dehydrogenate at 580 ° C for 10 hours, argon Put it in forcibly cooled and take out the rare earth permanent magnet material master alloy after reaching 40 ℃. The rare earth permanent magnet material master alloy is taken out in an inert gas environment, the oxygen content of the atmosphere in contact with the material is 200 ppm or less, and the recovered material is placed in a sealed container protected by nitrogen gas. Protect and grind with a ball mill to obtain an intermediate abrasive powder of 200 μm or less.

Finely pulverize with this new jet mill to obtain a rare earth alloy powder with an average particle size (SMD) of 3.2μm, add 0.2% of internal lubricant, and mix it in a sealed container protected by nitrogen gas for 180min. , Forming with a magnetic field orientation molding machine with a magnetic field orientation strength of 1.8T protected by nitrogen gas, the block density is 4.02 g / cm ³ , and after molding, put into a sintering furnace at 200-800 ° C Degreasing and degassing are performed for 8 hours, and sintering is performed at 1090 ° C. for 5 hours. In the case of sintering, argon of about 20 KPa is put in, heat-treated at 900 ° C. × 3 hr and 580 ° C. × 6 hr, cooled and taken out from the furnace, and then the raw material of the sintered rare earth permanent magnet material is obtained. A D10-10mm sample M1 is processed with the above-mentioned sintered rare earth permanent magnet material, and a performance test is performed.

  At the same time, the intermediate abrasive powder of 200 μm or less obtained with a conventional jet mill machine is finely crushed. The conventional jet mill does not have a constitution of lossless recovery of fine powder and ultrafine powder, and other operation processes completely coincide with the operation process by the new jet mill. Processing D10-10mm sample M2 with sintered rare earth permanent magnet material, and performance test.

  Table 1 shows the magnetic indices of M1 and M2, the amount of rare earth elements used in the smelting method, and the input and output of raw materials in the case of powder production.

  According to the data in the above table, when producing powder with the new jet mill device improved by the present invention, the recovery rate is improved to 0.47%, there is no powder in the filter, and the combustion process of ultra fine powder by the filter is unnecessary, When the same magnetism is achieved at the same time as the safety of production is improved, the weight percentage of rare earth elements falls from 31.2% to 30.8% as a melting component, and the relative usage of rare earth elements falls to 1.29% It is.

  As shown in FIG. 2, the principle of the conventional jet mill equipment is that the magnetic powder after intermediate polishing is polished before entering the cyclone. The magnetic powder is divided into fine powder and ultrafine powder by the action of the cyclone. Each of the two powders enters a collection tank by a collection system. After being polished with a conventional jet mill, there are two different tanks, each of which has fine or ultra fine powders.

  As shown in FIG. 3, as a novel jet mill equipment principle improved by the present invention, the magnetic powder after intermediate polishing is polished before entering the cyclone. The magnetic powder is divided into fine powder and ultrafine powder by the action of the cyclone. Each of the two powders enters the joint collection and mixing chamber through the collection system, and the two powders enter the tank through the collection and mixing chamber. Thereby, after polishing with the improved jet mill, there is only one tank, and there are fines and superfines at the same time in that tank.

  1) Nd, Pr, Dy, Co, Cu, Al, Fe, and ferroboron with a purity of at least 99% by weight are melted by high frequency in an argon atmosphere, and the melt is poured into dungenchirol to form an alloy. 24% Nd, 6.5% Pr, 0.5% Dy, 1% Co, 0.13% Cu, 0.5% Al, 1% B, and the rest are iron and unavoidable foreign matter. Then, ball mill pulverization was performed, and 0.5 wt% terbium hydride was added to the ball mill pulverized powder, and the two kinds of powders were mixed in 1 h.

  2) After mixing was completed, polishing was performed with a new jet mill, and the average particle size was controlled to 1 to 10 μm.

  3) Add 0.15wt% ethyl acetate to the polished magnetic powder and mix for 3h. After mixing is completed, orientation is performed with a magnetic field of 15KOe, press molding is performed, the block is formed, and the block is vacuum autoclave. Pre-sintering treatment was performed in a furnace. In this case, no pressure was applied, the presintering treatment temperature was 900 ° C., and the presintering treatment time was 85 minutes.

4) After pre-sintering is completed, autoclave treatment is performed by applying pressure. The autoclave temperature is 900 ° C, the pressure is 100 MPa, the autoclave time is 10 min. After that, a magnet having a density of 7.3 g / cm ³ or more was obtained.

  5) In 4), the magnet material after autoclaving was aged at 490 ° C for 4.5 hours to obtain a high coercivity magnet.

  The high coercive force magnet A1 was formed by the above process. For comparison, according to a magnet B1 prepared by grinding a mixed powder containing 0.5 wt% terbium hydride after ball milling with a conventional jet mill and pressing it with a mold in exactly the same manner as A1 for sintering aging.

  Table 2 shows the measurement results of the magnetism (residual magnetism Br, coercive force Hcj, (BH) max) of the magnets A1 and B1.

  Table 3 shows the measurement results of the components of the magnets A1 and B1.

  According to the component comparison, the loss of heavy rare earth element Tb in the jet mill is reduced with a new jet mill that does not discharge ultrafine powder.

  1) Nd, Pr, Dy, Co, Cu, Al, Fe, and ferroboron having a purity of at least 99% by weight are melted by high frequency in an argon atmosphere, and the melt is poured into dungenchirol to form an alloy. The alloy has a mass percentage of 23.5% Nd, 6.3% Pr, 1.4% Dy, 1.5% Co, 0.17% Cu, 0.55% Al, 1.02% B, and what remains is iron and inevitable foreign matter. This alloy fin was subjected to HD and ball mill pulverization treatment, and 0.8 wt% dysprosium fluoride was added to the ball mill pulverized powder.

  2) Two types of powders were polished by intermediate polishing and a jet mill, and the average particle size was controlled to 1 to 10 μm.

  3) Put 0.12wt% ethyl acetate into the polished magnetic powder and mix for 3h. After mixing is completed, press-mold by orientation with a magnetic field of 15KOe to form the block, and the block is vacuum autoclave furnace And presintering. In this case, no pressure was applied, the pre-sintering temperature was 880 ° C., and the time was 90 min.

4) After pre-sintering is completed, autoclave treatment is performed by applying pressure, the autoclave temperature is 910 ° C, the pressure is 120MPa, the time is 8min, and the pre-sintering material is processed by the above process Magnets with a density of 7.3 g / cm ³ or more were obtained.

  5) In 4), the magnet material after autoclaving was aged at 500 ° C. for 5.5 hours to obtain a high coercivity magnet.

  The high coercivity magnet A2 is formed by the above process. For comparison, the alloy fins having the same components were ground with HD and ball mill, and polished with a conventional jet mill, and the average particle size was controlled to 1 to 10 μm. 0.8 wt% dysprosium fluoride was added to the ground jet mill powder and mixed with a mixer. Press with mixed powder mold and follow magnet B2 prepared in the same way as A2 for sintering and sintering aging.

  Table 4 shows the measurement results of magnetism (residual magnetic Br, coercive force Hcj, (BH) max) of magnets A2 and B2.

  According to magnetism, the magnetism obtained by mixing two kinds of powders with a new jet mill that does not discharge ultrafine powder and mixing the two kinds of powders with a mixer was almost the same.

  Table 5 shows the measurement results of the components of the magnets A2 and B2.

  A2 and B2 magnets are processed into 10 pieces each and nickel-plated. After nickel plating was completed, the magnets were checked for bubbles and the results are shown in Table 6.

  According to the above results, it is possible to solve the problem of collecting powders in a conventional mixing process by mixing two kinds of powders with a new jet mill that does not discharge ultrafine powder.

  1) Nd, Pr, Dy, Co, Cu, Al, Fe, and ferroboron having a purity of at least 99% by weight are melted by high frequency in an argon atmosphere, and the melt is poured into dungenchirol to form an alloy. The mass percentage of the alloy is 20.8% Nd, 5.5% Pr, 4.5% Dy, 1.5% Co, 0.17% Cu, 0.2% Al, 0.99% B, and the remaining is iron and inevitable foreign matter. This alloy fin was subjected to HD and ball mill pulverization treatment, and a mixture of oxygenated dysprosium and dysprosium fluoride was added to the ball mill pulverized powder at a mass ratio of 2: 8, and the mixture included accounted for 1.0 wt% of the total weight.

  2) Two types of powders were polished with a new jet mill, and the average particle size was controlled to 1 to 10 μm.

  3) Put 0.15wt% methyl caprylate into the polished magnetic powder and mix for 3h. After mixing is completed, press-mold by orientation with a magnetic field of 15KOe, form the block, and vacuum autoclave the block Pre-sintering was performed in a furnace. In this case, no pressure was applied, the pretreatment temperature was 910 ° C., and the time was 80 min.

4) After pre-sintering is completed, autoclave treatment is performed by applying pressure, the autoclave temperature is 930 ° C, the pressure is 100MPa, the time is 7min, and the pre-sintering material is processed by the above process Magnets with a density of 7.3 g / cm ³ or more were obtained.

  5) In 4), the magnet material after autoclaving was aged at 500 ° C. for 5.5 hours to obtain a high coercivity magnet.

  The magnet A3 within the scope of the present invention is obtained by the above process. For comparison, a ball mill pulverized powder was charged with a mixture of oxygenated dysprosium and dysprosium fluoride at a mass ratio of 2: 8, and the charged mixture accounted for 1.0 wt% of the total weight. The mixed powder is polished with a conventional jet mill, pressed with a mold, and follows a magnet B3 prepared in exactly the same way as A3 for sintering aging.

  Table 7 shows the measurement results of magnetism (residual magnetic Br, coercive force Hcj, (BH) max) of magnets A3 and B3.

  Table 8 shows the measurement results of the components of magnets A3 and B3.

  According to the measurement results of the components, the loss of the heavy rare earth element Dy is reduced in a new jet mill that does not discharge ultrafine powder.

  1) Nd, Pr, Dy, Co, Cu, Al, Fe, and ferroboron having a purity of at least 99% by weight are melted by high frequency in an argon atmosphere, and the melt is poured into dungenchirol to form an alloy. The mass percentage of the alloy is 23.8% Nd, 6.3% Pr, 1.3% Dy, 1.5% Co, 0.17% Cu, 0.5% Al, 1% B, and the remainder is iron and inevitable foreign matter. This alloy fin was subjected to HD and ball mill pulverization treatment, and 0.5% terbium was added to the ball mill pulverized powder.

  2) Two materials were polished with a new jet mill, and the average particle size was controlled to 1 to 10 μm.

  3) Put 0.15wt% methyl caprylate into the polished magnetic powder and mix for 3h. After mixing is completed, press-mold by orientation with a magnetic field of 15KOe, form the block, and vacuum autoclave the block Pre-sintering was performed in a furnace. In this case, no pressure was applied, the pretreatment temperature was 930 ° C., and the time was 75 minutes.

4) After pre-sintering is completed, autoclave treatment is performed by applying pressure, the autoclave temperature is 920 ° C, the pressure is 120MPa, the time is 6min, and the pre-sintering material is processed by the above process Magnets with a density of 7.3 g / cm ³ or more were obtained.

  5) In 4), the magnet material after autoclaving was aged at 500 ° C. for 5.5 hours to obtain a high coercivity magnet.

  The magnet A4 within the scope of the present invention was obtained by the above process. For comparison, according to a magnet B4 prepared by grinding a mixed powder containing 0.5 wt% terbium after ball milling with a conventional jet mill and pressing it with a mold in exactly the same manner as A4 for sintering aging.

  Table 9 shows the measurement results of the magnetic properties (residual magnetism Br, coercive force Hcj, (BH) max) of magnets A4 and B4.

  Table 10 shows the measurement results of the components of magnets A4 and B4.

  According to the measurement results of the components, the loss of heavy rare earth element Tb in the jet mill is reduced with a new jet mill that does not discharge ultrafine powder.

  1) Nd, Pr, Dy, Co, Cu, Al, Fe, and ferroboron having a purity of at least 99% by weight are melted by high frequency in an argon atmosphere, and the melt is poured into dungenchirol to form an alloy. The alloy had a mass percentage of 23.8% Nd, 6.3% Pr, 1.3% Dy, 1.5% Co, 0.17% Cu, 0.5% Al, 1% B, and the remainder was iron and inevitable foreign matter. This alloy fin was subjected to HD and ball mill pulverization treatment, and 0.8% dysprosium was added to the ball mill pulverized powder.

  2) Polish two kinds of materials with a new jet mill and control the average particle size to 1-10 μm.

  3) Put 0.15wt% methyl laurate into the polished magnetic powder and mix for 3h. After mixing is completed, press and form by the magnetic field of 15KOe, form the block, vacuum autoclave the block Pre-sintering was performed in a furnace. In this case, no pressure was applied, the pretreatment temperature was 950 ° C., and the time was 65 min.

4) After pre-sintering is completed, autoclave treatment is performed by applying pressure, the autoclave temperature is 930 ° C, the pressure is 110MPa, the time is 6min, and the pre-sintering material is processed by the above process Magnets with a density of 7.3 g / cm ³ or more were obtained.

  5) 4) The magnet material after autoclaving was aged at 490 ° C for 4.5 hours to obtain a high coercivity magnet.

  The magnet A5 within the scope of the present invention was obtained by the above process. For comparison, the alloy fins having the same components were ground with HD and ball mill, and polished with a conventional jet mill, and the average particle size was controlled to 1 to 10 μm. 0.8 wt% dysprosium was put into the ground jet mill powder and mixed with a mixer. According to the magnet B5, which is pressed in the powder mold after mixing, sintered and prepared in exactly the same way as A5 for sintering aging.

  Table 11 shows the measurement results of magnetism (residual magnetic Br, coercive force Hcj, (BH) max) of magnets A5 and B5.

  The measurement results of the components of magnets A5 and B5 are shown in Table 12.

  A5 and B5 magnets are processed into 10 pieces each and nickel-plated. After nickel plating was completed, the magnet was checked for bubbles and the results are shown in Table 13.

  According to the above results, it is possible to solve the problem that two kinds of powders are mixed in a new jet mill that does not discharge ultrafine powder, and the powder in the conventional mixing process is collected.

  Although the foregoing is only a part of the embodiments of the present invention, the present invention is not limited thereto, and all modifications, equivalent replacements and improvements are within the scope of the present invention within the spirit or principle of the present invention. is there.

1 ... Upper tank
2 ... Silo
3 ... Vibration loader
4 Loading interface gas switching valve
5 ... Classifier motor
6 ... Classifier
7 ... Load cell
8 ... Polishing chamber
9 ... Recovery tank
10 ... Interface gas switching valve
11 ... Vibrator
12 ... Lossless collection and mixing chamber for fine and ultra fine powders
13 ... Double flap valve
14 ... Ultra fine filter
15 Cyclone
15.1 ... Cyclone outlet end No.1
15.2 ... Cyclone outlet end No.2
16 ... Outlet valve
17 ... Compressor

Claims (4)

1) R ¹ -Fe-BM alloy powder is obtained by stop zone-hydrogen explosion, and R ¹ -Fe-BM alloy powder contains R ¹ -Fe-BM alloy powder with heavy rare earth powder R ² or heavy rare earth Put powder R ² X and mix to get mixed powder. Among them, R ¹ is ^one of rare earth elements, the content of R ¹ is 26 wt% <R ¹ <35 wt%, the content of B is 0.8 wt% to 1.3 wt%, and M is Ti, V, Cr , Mn, Co, Ga, Cu, Si, Al, Zr, Nb, W, Mo is one or more, M content is 5wt% or less, the remaining is iron and inevitable foreign matter Yes, R ² is at least one of Dy, Tb, and Ho, X is at least one of O, H, and F, and R ² or R ² X is the total weight of the R ¹ -Fe-BM alloy powder Of 0.1 wt% to 1.5 wt%.
2) Polish the mixed powder with a new jet mill to obtain magnetic powder. The average particle size of the magnetic powder is controlled to 1 to 10 μm.
3) Add 0.1-0.3wt% fatty acid ester to the magnetic powder polished in 2), mix for 0.1-3h, and push the magnetic powder into the block. The block is pre-sintered in a vacuum autoclave furnace without applying pressure.
4) After completing the pre-sintering treatment, autoclave treatment is performed by applying pressure to obtain a magnet material having a density of 7.3 g / cm ³ or more.
5) In 4), the magnet material after autoclaving is subjected to aging treatment to obtain a high coercivity magnet.   3. The method according to claim 1, wherein the temperature of the pre-sintering treatment is ≦ 950 ° C. and the time is ≧ 60 min in 3).   The method according to claim 1, wherein the autoclave temperature is 700 to 1000 ° C, the pressure is 30 to 150 MPa, and the time is 2 to 30 min.   5. The method according to claim 1, wherein the aging treatment is performed at 400 to 600 ° C. for 3 to 6 hours.

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