Magnetic steel dysprosium infiltration treatment process and spray coating device for magnetic steel dysprosium infiltration

Abstract

The invention discloses a magnetic steel dysprosium infiltration treatment process and a spray coating device for magnetic steel dysprosium infiltration, and belongs to the technical field of waste magnetic steel recovery treatment. Dysprosium permeation treatment is carried out through the following steps of S1, magnetic steel pretreatment, wherein an oxide layer and rust on the surface of magnetic steel are removed, and heat treatment is carried out; s2, dysprosium powder is prepared, specifically, dysprosium powder is prepared through a chemical reduction method; s3, dysprosium slurry preparation, wherein dysprosium powder and an ethanol solution are mixed to prepare dysprosium slurry; s4, dysprosium slurry spraying: uniformly spraying the dysprosium slurry on the surface of the magnetic steel; s5, dysprosium powder infiltration promotion treatment: carrying out vacuum high-temperature sintering or laser shock infiltration promotion; s6, post-processing: performing grinding machine processing and electroplating electrophoresis processing on the magnetic steel subjected to dysprosium infiltration; the dysprosium slurry is sprayed by adopting the jet coating device provided by the invention; the dysprosium infiltration rate in the dysprosium infiltration process is effectively increased, and the actual utilization rate of raw materials is increased; most importantly, it is guaranteed that enough dysprosium materials permeate into the magnetic steel, and therefore the magnetic steel has the optimal coercive force and temperature resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of waste magnetic steel recycling and treatment, and specifically relates to a magnetic steel dysprosium infiltration treatment process and a spray coating device for magnetic steel dysprosium infiltration. Background Art

[0002] The electric vehicle wheel hub magnet is an important component of the electric vehicle wheel hub and has an important impact on the performance of the electric vehicle. The electric vehicle wheel hub magnet is placed in the wheel hub and cooperates with the rim and other components to form the electric vehicle's motor hub.

[0003] Metallic dysprosium is a rare earth element that plays an important role in magnetic steel. By adding an appropriate amount of metallic dysprosium, the magnetic properties and high temperature resistance of the magnetic steel can be significantly improved. Generally speaking, the content of metallic dysprosium in the magnetic steel is controlled between 0.3% and 5% to ensure that the magnetic steel can achieve the best coercive force and maximum magnetic energy product. In addition, the addition of an appropriate amount of metallic dysprosium can also improve the high temperature resistance of the magnetic steel. The electric vehicle motor will generate a lot of heat during operation, resulting in a high temperature environment. When the motor stops working, the temperature drops. The alternation of hot and cold will cause a pressure difference in the internal air. External water vapor and dust will enter the motor through various small gaps, causing oxidation and rust of the dysprosium in the magnetic steel, and dysprosium loss or partial demagnetization will eventually lead to demagnetization. The loss of dysprosium in the magnetic steel can cause problems such as reduced power and increased noise in electric vehicles.

[0004] In case of dysprosium loss in the magnet, in addition to replacing a new magnet, the magnet can also be repaired by infiltrating dysprosium into the interior of the magnet while ensuring that the overall structure of the magnet is intact. The new dysprosium can then be infiltrated into the interior of the magnet, and the repaired magnet can be reused. The prior art dysprosium infiltration process directly coats the dysprosium slurry on the surface of the magnet to form a dysprosium metal coating on the surface of the magnet. The magnet is then sent to a high-temperature environment for sintering, and the dysprosium metal is infiltrated into the interior of the magnet by the high temperature. However, the dysprosium thin film coating formed by direct spraying is usually poor in bonding with the surface of the magnet. During the sintering process, the solvent in the dysprosium slurry evaporates rapidly at high temperatures, causing some dysprosium powder to peel off the surface of the magnet before it has infiltrated into the magnet. This part of the dysprosium powder cannot infiltrate into the interior of the magnet, resulting in a decrease in the infiltration rate of the dysprosium powder and a decrease in the utilization rate of the dysprosium metal raw material. Insufficient infiltration of dysprosium into the magnet may affect the coercive force and temperature resistance of the repaired magnet. Summary of the invention

[0005] The present invention provides a magnetic steel dysprosium infiltration treatment process. While spraying dysprosium slurry on the magnetic steel, the sprayed slurry is supplemented with magnetron sputtering treatment, so that dysprosium ions as target materials form magnetron sputtering and collide with a substrate, that is, the surface of the magnetic steel at a high speed; compared with directly spraying dysprosium metal slurry on the surface of the magnetic steel, the magnetron sputtering treatment can make the dysprosium metal ions firmly adhere to the surface of the magnetic steel, and in the later stage of the infiltration promotion treatment, the dysprosium stripping amount is reduced, the penetration rate of the dysprosium material into the interior of the magnetic steel is increased, and the actual utilization rate of the raw materials is improved; the most important thing is to ensure that a sufficient amount of dysprosium material is infiltrated into the magnetic steel, so that the magnetic steel has the best coercive force and temperature resistance.

[0006] In order to achieve the above technical objectives, the present invention is implemented by the following technical solutions: A magnetic steel dysprosium infiltration treatment process comprises the following steps: S1: Magnetic steel pretreatment: cleaning and removing dirt, oxide layer and rust on the surface of the magnetic steel; and heat treatment of the magnetic steel; S2: Preparation of dysprosium powder: using chemical reduction method, using dysprosium ion solution as raw material, reacting with reducing agent to produce precipitation, and filtering and washing to obtain metal dysprosium powder; S3: Preparation of dysprosium slurry: mixing the prepared metal dysprosium powder with an ethanol solution to prepare a dysprosium slurry; the ratio of the ethanol solution to the dysprosium powder is 8-12:2-5; S4: Dysprosium slurry spraying: Dysprosium slurry is sprayed on the surface of the magnetic steel through a spray coating device; while spraying the dysprosium slurry, magnetron sputtering treatment is performed; S5: Dysprosium powder infiltration promotion treatment: the magnetic steel with the dysprosium slurry coating sprayed on the surface is subjected to dysprosium powder infiltration promotion treatment, so that the dysprosium powder particles infiltrate into the interior of the magnetic steel; The dysprosium powder infiltration-promoting treatment includes: vacuum high-temperature sintering or laser shock infiltration-promoting; S6: Post-processing: After the dysprosium-infiltrated magnetic steel is polished and repaired by a grinder and then electroplated and electrophoresed, the magnetic steel product is obtained; An organic silicon sol protective layer is coated on the surface of the prepared magnetic steel product.

[0007] Preferably, the cleaning solution in S1 uses dilute nitric acid with a concentration of 3% to 5% to clean the magnetic steel to remove the oxide layer and rust.

[0008] After cleaning, diamond raw material is used to perform sandblasting and grinding on the surface of the magnetic steel, and the particle size of the diamond raw material is not less than 100 meshes.

[0009] Preferably, after the magnetic steel is cleaned in S1, it is placed in a heat treatment furnace and kept at 600-800°C for 20-40 minutes; then the temperature is gradually increased to 900-1000°C and kept for 300-350 minutes; After the heat-treated magnetic steel is taken out of the furnace, it is immediately placed in cold water for water quenching cooling; The heat-treated magnetic steel is placed in a strong magnetic field, and the waste dysprosium powder particles inside it, especially in the cracks, are cleaned out by magnetic suction; Through heat treatment, the magnetic particles inside the magnet are changed into order, and the size and shape of the crystal structure are controlled, so that the magnet has better permeability and the dysprosium particles can penetrate into the magnet more easily.

[0010] Preferably, in the preparation of the dysprosium powder, dysprosium nitrate is used as a raw material, which is dissolved in deionized water to obtain a dysprosium nitrate solution; hydrogen is introduced into the dysprosium nitrate solution, and the reaction is carried out at 1000-1300° C. for 1-3 hours; After the reaction is complete, the precipitate generated by the reaction is filtered, and the metal dysprosium powder is obtained by washing and drying.

[0011] Preferably, the ethanol concentration in the preparation of the dysprosium slurry is 30%; and the mixing ratio of the ethanol solution to the dysprosium powder is 10:3.

[0012] Preferably, before spraying the dysprosium slurry, the magnetic steel is completely immersed in the dysprosium slurry for 4 to 8 hours; The immersion process allows some dysprosium particles to fill the gaps on the surface of the magnetic steel or the uneven areas on the surface of the magnetic steel; these hidden dead corners cannot be covered with a dysprosium slurry by spraying.

[0013] Preferably, the vacuum high temperature sintering to promote infiltration is as follows: placing the magnetic steel sprayed with dysprosium slurry into a metal box, and evacuating the box; placing the vacuumized metal box together with the magnetic steel into a sintering furnace; Raise the temperature in the sintering furnace to 800~1000℃ and maintain it for 4~6 hours; After high-temperature sintering, the magnetic steel is cooled to room temperature and then placed in the sintering furnace again for low-temperature tempering. The low-temperature tempering temperature is raised to 400~600℃ and kept warm for 2~4 hours. After cooling to room temperature, the dysprosium infiltration treatment is completed.

[0014] Preferably, the specific method of laser shock penetration is: putting the magnetic steel with dysprosium slurry adhered to the surface into the organic glass cover, setting an interlayer inside the organic glass plate, and pouring clean water into the interlayer; The laser shock wave passes through the organic glass and acts on the surface of the magnetic steel. Under the action of the laser shock pulse, the dysprosium ions are promoted to penetrate into the interior of the magnetic steel. In addition to promoting the penetration of dysprosium into the magnetic steel, laser shock can also form a deeper residual stress layer on the surface of the magnetic steel, refine the magnetic steel grains, and improve the overall fatigue life of the magnetic steel.

[0015] Another object of the present invention is to provide a spray coating device for magnetic steel dysprosium infiltration, comprising: a slurry storage box, a spray barrel, an air pump, an electrostatic generator, and a spray box; The dysprosium slurry is stored in the slurry storage box; The discharge port of the slurry storage box is connected to the feed pipe below the spraying cylinder through a feed pipe; A suction pump is arranged on the feed pipe; the dysprosium slurry is pumped from the slurry storage tank into the spray barrel by the suction pump; The first end of the spray pipe is arranged on the discharge port of the spray barrel, and the first end of the spray pipe extends into the spray barrel; the second end of the spray pipe extends into the spray box; The air pump is connected to the spray barrel through an air jet pipe; the air pump provides a high-pressure airflow to promote the spraying of the dysprosium slurry in the spray barrel; The electrostatic generator is used to make the dysprosium ions in the dysprosium slurry have static electricity, thereby enhancing the adsorption strength between the dysprosium ions and the magnetic steel.

[0016] Preferably, a magnetron sputtering assembly is provided on the spray box; the magnetron sputtering assembly is used to form an electric field inside the spray box and to introduce argon gas into the spray box.

[0017] Preferably, a conical cover is arranged inside the spray barrel, and the lower edge of the conical cover is connected to the inner wall of the spray barrel; the conical cover isolates an independent space inside the spray barrel; The feed pipe below the spray barrel is in communication with the independent space; The upper end opening of the conical cover is connected to the first end of the spray pipe; The air injection pipe is communicated with the material injection pipe.

[0018] Preferably, the portion of the spray pipe located inside the spray barrel is made of conductive metal material; The electrostatic wire of the electrostatic generator is introduced into the spray barrel and connected to the spray pipe.

[0019] Preferably, the spray pipe is located in the spray box and has a plurality of spray outlets; A set of nozzle assemblies is arranged on each of the ejection ports; The nozzle assembly comprises: a bending molding tube, a lining hose and a spray head; The first end of the lining hose is connected to the spray port, and the second end of the lining hose is connected to the spray head; the outer side of the lining hose is covered with the bending molding tube 。

[0020] Preferably, a suction pump is provided at the bottom of the spray box, and the suction pump is connected to the slurry storage box through a recovery pipe; The suction pump sucks the residual dysprosium powder that falls into the spray box into the slurry storage box for raw material recovery.

[0021] The beneficial effects of the present invention are: The present invention provides a magnetic steel dysprocket treatment process, which is used to perform dysprocket treatment on the aged magnetic steel of the electric vehicle wheel hub, so as to restore the coercive force and temperature resistance of the magnetic steel, so as to achieve reuse without replacement, thereby improving the utilization rate of the magnetic steel repair; After the aged magnetic steel is disassembled, it is pre-treated and cleaned, and then heat treated. The crystal size and shape of the magnetic steel are optimized through heat treatment, so that the magnetic steel has better permeability in the subsequent dysprosium-promoted infiltration process; the infiltration rate of dysprosium material is improved; The dysprosium slurry is sprayed on the surface of the magnetic steel by a spray coating device. During the spraying process, it is assisted by magnetron sputtering. Under the action of magnetron sputtering, the thin film formed by the dysprosium slurry on the surface of the magnetic steel has a stronger deposition effect, and the dysprosium material has a stronger adhesion to the surface of the magnetic steel; in the subsequent penetration promotion process, part of the dysprosium material is prevented from peeling off the surface of the magnetic steel, affecting the effective penetration amount of the dysprosium material and the waste of dysprosium raw materials; The process of promoting the penetration of dysprosium material adopts laser shock. Laser shock causes the dysprosium slurry coating to form a plasma shock wave, which propagates into the interior of the magnetic steel to achieve the purpose of promoting the penetration of dysprosium material. In addition, after the action of the plasma shock wave, a residual compressive stress layer of a certain depth can be formed on the surface of the magnetic steel, which has a strengthening effect on the surface of the magnetic steel and can improve the wear resistance, stress corrosion resistance and fatigue resistance of the magnetic steel itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the process flow of dysprosium infiltration treatment of magnetic steel according to the present invention; Figure 2 It is a schematic diagram of the overall structure of the spray coating device for dysprosium infiltration of magnetic steel provided by the present invention; Figure 3 It is a schematic diagram of the internal structure of the spray barrel in the spray coating device of the present invention; Figure 4 The present invention Figure 3 The partial enlarged schematic diagram A in the figure is specifically a powder filter membrane cover provided at the port of the air jet pipe; Figure 5 It is a schematic diagram of the structure of the bending molding tube and the spray head of the present invention; Figure 6 It is a schematic diagram of the structure of the lining hose inside the bending and shaping tube of the present invention.

[0024] In the accompanying drawings, the structural names represented by the reference numerals are: 1- spray box, 2- spray pipe, 201- bending molding tube, 2011- lined hose, 202- spray head, 3- spray barrel, 301- cone cover, 302- feed pipe, 4- electrostatic generator, 401- electrostatic wire, 5- slurry storage box, 501- recovery pipe, 6- air pump, 601- jet pipe, 6011- filter powder membrane cover, 7- suction pump. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Embodiment 1, as Figure 1 As shown, this embodiment provides a magnetic steel dysprosium infiltration treatment process, comprising the following steps: S1: Magnetic steel pretreatment: Wipe the dirt off the surface of the disassembled aged magnetic steel; prepare a 3% to 5% dilute nitric acid solution, the concentration of which can be 3%, 4%, 5%, or any other value within the above concentration range; soak the aged magnetic steel in the dilute nitric acid for 20 to 40 minutes, and the specific reaction time is adjusted according to the degree of oxidation and rust on the surface of the magnetic steel; allow the oxide layer and rust on the surface of the aged magnetic steel to fully react with the dilute nitric acid to achieve the purpose of removal; After the oxide layer and rust are removed, the magnetic steel is sandblasted and polished, with diamond as the sandblasting material, and the diamond particle size is not less than 100 mesh; the residual rust and rough parts on the surface of the magnetic steel are removed by sandblasting; After long-term use, the crystal structure of the magnetic steel changes with the aging of the material, which is not conducive to the subsequent penetration of dysprosium into the interior of the magnetic steel. Therefore, the pretreatment of this embodiment also includes heat treatment of the magnetic steel. The cleaned magnetic steel is placed in a heat treatment furnace. The first stage is at a temperature of 600-800°C and kept warm for 20-40 minutes. This embodiment sets the temperature of the first stage at 700°C and keeps warm for 30 minutes. In the second stage, the temperature is gradually increased to 900-1000°C and kept warm for 300-350 minutes. This embodiment sets the temperature of the second stage at 1000°C and keeps warm for 350 minutes. After the heat-treated magnetic steel is taken out of the furnace, it is immediately placed in cold water for water quenching treatment; after a long period of heat treatment, the magnetic steel can achieve the purpose of internal crystal reordering, optimize the internal crystal structure and shape, and improve the penetration performance of the magnetic steel; The aging of magnetic steel is mainly due to the loss of rare earth elements inside, such as dysprosium. However, some dysprosium particles with weakened magnetism may still remain in some gaps or recessed corners inside the magnetic steel. These dysprosium materials cannot be cleaned out by cleaning, and these dysprosium materials remaining in the magnetic steel cannot play their due functions, but will affect the penetration of new dysprosium materials. Therefore, this embodiment also performs waste treatment on the magnetic steel, and uses the remaining magnetism of the old dysprosium material itself to put the magnetic steel into a strong magnetic field, and use the magnetic field to magnetically absorb and discharge the aged dysprosium materials remaining in the gaps or recessed corners of the magnetic steel as much as possible, so that more space is released inside the magnetic steel for the penetration of new dysprosium materials. S2: Preparation of dysprosium powder: using dysprosium nitrate as a raw material, dissolving dysprosium nitrate in deionized water to prepare a dysprosium nitrate aqueous solution; The dysprosium nitrate aqueous solution is heated, and while heating, a reducing gas, hydrogen, is introduced into the dysprosium nitrate aqueous solution to cause a reduction reaction; the heating temperature is set to 1000-1300° C., and the reaction time is 1-3 hours. According to the actual reaction situation, the specific values ​​of the heating temperature and the reaction time can be within the above temperature range; as the heating proceeds, precipitation begins to appear, and when the precipitated material no longer increases and the reaction is complete, the precipitate is filtered and washed with deionized water, and the washed precipitate is dried to prepare dysprosium powder; In addition to the chemical reduction method for preparing dysprosium powder, the dysprosium material inside can also be directly recovered from scrapped magnetic steel. For some magnetic steels whose structures have been destroyed and cannot be reused, the rare earth elements inside, including dysprosium, can be obtained through dissolution, separation, and purification. This method has low raw material costs and achieves the secondary utilization of scrapped raw materials. However, the requirements for separation and purification are relatively high, because only a part of the dysprosium material in the scrapped magnetic steel has reuse value, so the dysprosium material production rate is lower than that of direct preparation. S3: Preparation of dysprosium slurry: dissolving the prepared dysprosium powder in ethanol with a concentration of 30%; the fraction ratio of the ethanol solution to the dysprosium powder is 8-12:2-5; in this embodiment, the fraction ratio of the ethanol solution to the dysprosium powder is set to 10:3; the dysprosium powder is dissolved in the ethanol solution to prepare a dysprosium slurry; S4: Dysprosium slurry spraying: For the uneven dead corners on the surface of the magnetic steel, or some cracks on the surface of the magnetic steel, the dysprosium slurry may not be able to cover the above dead corners or gaps directly by spraying; therefore, before spraying the dysprosium slurry, the magnetic steel is completely immersed in the dysprosium slurry for 4 to 8 hours; through the soaking for a sufficient period of time, the dysprosium slurry is immersed in the above-mentioned uneven dead corners or gaps to form a dysprosium slurry film; at the same time, a layer of dysprosium slurry film can be formed on the surface of the magnetic steel in advance, and the deposition amount of dysprosium on the surface of the magnetic steel can be increased by superimposing the later spraying; After soaking, the magnetic steel is placed in the spray box of the spray coating device, and the dysprosium slurry is sprayed on the surface of the magnetic steel to form a dysprosium film layer; the adhesion between the dysprosium film formed on the surface of the magnetic steel, especially on the smoother part, and the magnetic steel is not strong enough. In the subsequent penetration promotion process, when the solvent evaporates, the dysprosium powder is likely to be peeled off from the magnetic steel before it can penetrate into the magnetic steel, which ultimately reduces the penetration rate of the dysprosium material; Therefore, in addition to conventional electrostatic spraying, this embodiment also uses magnetron sputtering technology to enhance the potential energy of target ions, that is, dysprosium particles incident on the magnetic steel surface, so that the dysprosium film has a stronger deposition effect on the magnetic steel surface, and improves the adhesion between the dysprosium film and the magnetic steel surface; ensures the penetration rate of the dysprosium film; S5: Dysprosium powder infiltration treatment: This embodiment adopts a vacuum high-temperature sintering method to perform infiltration treatment on the dysprosium material. First, the magnetic steel sprayed with the dysprosium slurry is placed in a metal box, and the box is sealed; the metal box is evacuated, and the vacuumized metal box and the magnetic steel inside are placed in a sintering furnace; the temperature in the high-temperature sintering stage is increased to 800-1000°C. In this embodiment, the sintering temperature is set to 900°C. In addition, other temperature values ​​can be used as long as the sintering temperature value is within the above temperature range; sintering is performed at 900°C for 4-6 hours; Keeping the magnet sintered in a vacuum environment can prevent the magnet and the dysprosium slurry coating from coming into contact with oxygen and reacting, thereby improving the purity of the material and preventing the impurities produced by sintering from affecting the material properties; in a vacuum environment, the dysprosium particles on the surface of the magnet are easier to diffuse and migrate; After high-temperature sintering, the magnetic steel is cooled to room temperature and then put into the sintering furnace again for low-temperature tempering. The low-temperature tempering temperature is raised to 400~600℃ and kept warm for 2~4 hours. After the low-temperature tempering is completed, it is cooled to room temperature, and the dysprosium infiltration of the magnetic steel is completed. Through low-temperature tempering, the brittleness of the magnetic steel is eliminated and its toughness is improved. S6: Post-processing: The magnet that has been infiltrated with dysprosium needs to be repaired by grinding on a grinder in order to smooth out any excess parts that may exist on the surface of the magnet. According to installation requirements, if the magnet is too large and cannot be fitted, it will be ground to the appropriate size. After grinding, an organic silicon sol protective layer is coated on the surface of the magnet.

[0027] Embodiment 2, as Figure 1 As shown, this embodiment provides a magnetic steel dysprosium infiltration treatment process, comprising the following steps: S1: Magnetic steel pretreatment: Wipe the dirt off the surface of the disassembled aged magnetic steel; prepare a dilute nitric acid solution with a concentration of 3% to 5%, and the concentration of the dilute nitric acid can be 3%, 4%, 5%, or any other value within the above range; soak the aged magnetic steel in the dilute nitric acid solution for 20 to 40 minutes, and the specific reaction time is adjusted according to the degree of oxidation and rust on the surface of the magnetic steel; make the oxide layer and rust on the surface of the aged magnetic steel fully react with the dilute nitric acid to achieve the purpose of cleaning; After the oxide layer and rust are removed, the magnetic steel is sandblasted and polished, with diamond as the sandblasting material, and the diamond particle size is not less than 100 mesh; the residual rust and rough parts on the surface of the magnetic steel are removed by sandblasting; After long-term use, the crystal structure of the magnetic steel changes with the aging of the material, which is not conducive to the subsequent penetration of dysprosium into the interior of the magnetic steel. Therefore, the pretreatment of this embodiment also includes heat treatment of the magnetic steel. The cleaned magnetic steel is placed in a heat treatment furnace. The first stage is at a temperature of 600-800°C and kept warm for 20-40 minutes. This embodiment sets the temperature of the first stage at 700°C and keeps warm for 30 minutes. In the second stage, the temperature is gradually increased to 900-1000°C and kept warm for 300-350 minutes. This embodiment sets the temperature of the second stage at 1000°C and keeps warm for 350 minutes. After the heat-treated magnetic steel is taken out of the furnace, it is immediately placed in cold water for water quenching treatment; after a long period of heat treatment, the magnetic steel can achieve the purpose of internal crystal reordering, optimize the internal crystal structure and shape, and improve the penetration performance of the magnetic steel; The aging of magnetic steel is mainly due to the loss of rare earth elements inside, such as dysprosium. However, some dysprosium particles with weakened magnetism may still remain in some gaps or recessed corners inside the magnetic steel. These dysprosium materials cannot be cleaned out by cleaning, and these dysprosium materials remaining in the magnetic steel cannot play their due functions, but will affect the penetration of new dysprosium materials. Therefore, this embodiment also performs waste treatment on the magnetic steel, and uses the remaining magnetism of the old dysprosium material itself to put the magnetic steel into a strong magnetic field, and use the magnetic field to magnetically absorb and discharge the aged dysprosium materials remaining in the gaps or recessed corners of the magnetic steel as much as possible, so that more space is released inside the magnetic steel to penetrate the new dysprosium material. S2: Preparation of dysprosium powder: using dysprosium nitrate as a raw material, dissolving dysprosium nitrate in deionized water to prepare a dysprosium nitrate aqueous solution; The dysprosium nitrate aqueous solution is heated, and while heating, a reducing gas, hydrogen, is introduced into the dysprosium nitrate aqueous solution to cause a reduction reaction; the heating temperature is set to 1000-1300° C., and the reaction time is 1-3 hours. According to the actual reaction situation, the specific values ​​of the heating temperature and the reaction time can be within the above temperature range; as the heating proceeds, precipitation begins to appear, and when the precipitated material no longer increases and the reaction is complete, the precipitate is filtered and washed with deionized water, and the washed precipitate is dried to prepare dysprosium powder; In addition to the chemical reduction method for preparing dysprosium powder, the internal dysprosium material can also be directly recovered from scrapped magnetic steel. For some magnetic steels whose structures have been destroyed and cannot be reused, dysprosium materials can be obtained by dissolving, separating and purifying. This method has low raw material costs and achieves the secondary utilization of scrapped raw materials. However, it has high requirements for separation and purification, because only a part of the dysprosium material in the scrapped magnetic steel has reuse value, so the yield of dysprosium material is lower than that of direct preparation. S3: Preparation of dysprosium slurry: dissolving the prepared dysprosium powder in ethanol with a concentration of 30%; the fraction ratio of the ethanol solution to the dysprosium powder is 8-12:2-5; in this embodiment, the fraction ratio of the ethanol solution to the dysprosium powder is set to 10:3; the dysprosium powder is dissolved in the ethanol solution to prepare a dysprosium slurry; S4: Dysprosium slurry spraying: For some corners of the uneven surface of the magnetic steel, or some cracks on the surface of the magnetic steel, the dysprosium slurry may not be able to cover the above-mentioned corners or gaps directly by spraying; therefore, before spraying the dysprosium slurry, the magnetic steel is completely immersed in the dysprosium slurry for 4 to 8 hours; through sufficient soaking time, the dysprosium slurry is immersed in the above-mentioned corners or gaps to form a dysprosium slurry film; at the same time, a layer of dysprosium slurry film can be formed on the surface of the magnetic steel in advance, and superimposed with the later spraying, the deposition amount of dysprosium on the surface of the magnetic steel can be increased; After soaking, the magnetic steel is placed in the spray box of the spray coating device, and the dysprosium slurry is sprayed on the surface of the magnetic steel to form a dysprosium film layer; the adhesion between the dysprosium film formed on the surface of the magnetic steel, especially on the smoother part, and the magnetic steel is not strong enough. In the subsequent penetration promotion process, when the solvent evaporates, the dysprosium powder is likely to be peeled off from the magnetic steel before it can penetrate into the magnetic steel, which ultimately reduces the penetration rate of the dysprosium material; Therefore, in addition to conventional electrostatic spraying, this embodiment also uses magnetron sputtering technology to enhance the potential energy of target ions, that is, dysprosium particles incident on the magnetic steel surface, so that the dysprosium film has a stronger deposition effect on the magnetic steel surface, and improves the adhesion between the dysprosium film and the magnetic steel surface; ensures the penetration rate of the dysprosium film; S5: Dysprosium powder infiltration treatment: This embodiment adopts laser shock infiltration treatment: the magnetic steel with dysprosium slurry adhered to the surface is placed in the organic glass cover, an interlayer is set inside the organic glass plate, and clean water is poured into the interlayer; the organic glass and clean water serve as a constraint layer; The laser shock wave passes through the organic glass and acts on the surface of the magnetic steel. Under the action of the laser shock pulse, the dysprosium ions are promoted to penetrate into the interior of the magnetic steel. The laser shock forms a plasma shock wave, which propagates into the interior of the magnetic steel to achieve the purpose of penetrating the dysprosium material into the interior of the magnetic steel. After the plasma shock wave acts, a residual compressive stress layer of a certain depth can be formed on the surface of the magnetic steel, which has a strengthening effect on the surface of the magnetic steel and can improve the wear resistance, stress corrosion resistance and fatigue resistance of the magnetic steel itself. S6: Post-processing: The magnet that has been infiltrated with dysprosium needs to be repaired by grinding on a grinder in order to smooth out any excess parts that may exist on the surface of the magnet. According to installation requirements, if the magnet is too large and cannot be fitted, it will be ground to the appropriate size. After grinding, an organic silicon sol protective layer is coated on the surface of the magnet.

[0028] Embodiment 3, a spray coating device for magnetic steel dysprosium infiltration, comprising: a slurry storage box 5, a spray barrel 3, an air pump 6, an electrostatic generator 4, and a spray box 1; like Figure 2 As shown, the slurry storage box 5 is used to store the prepared dysprosium slurry, and the discharge port of the slurry storage box 5 is connected to the feed pipe 302 below the spray barrel 3 through the feed pipe; a suction pump 7 is arranged on the feed pipe, and the dysprosium slurry in the slurry storage box 5 can be pumped into the spray barrel 3 by the suction pump 7, and the spray barrel 3 is provided with a discharge port at the upper position, and a spray pipe 2 is arranged on the discharge port, and the first end of the spray pipe 2 extends through the discharge port into the spray barrel 3; the second end of the spray pipe 2 extends into the spray box 1; the dysprosium slurry entering the spray barrel 3 is sprayed in the spray box 1 through the spray pipe 2, and sprayed on the surface of the magnetic steel to form a dysprosium slurry coating; like Figure 3 As shown, a conical cover 301 is arranged inside the spray barrel 3, and the lower side edge of the conical cover 301 is connected to the inner wall of the spray barrel 3, and the conical cover 301 isolates an independent space in the spray barrel 3; the feed pipe 302 below the spray barrel 3 is connected to the independent space, and the dysprosium slurry entering the spray barrel 3 from the feed pipe 302 actually enters the independent space; the first end of the spray pipe 2 is connected to the upper end opening of the conical cover 301, and the dysprosium slurry entering the independent space is sprayed out through the spray pipe 2; This embodiment uses an air spray mode to accelerate the spraying of the dysprosium slurry, and an electrostatic generator 4 is provided to make the dysprosium element particles sprayed from the dysprosium slurry carry static electricity, which helps them adhere to the surface of the magnetic steel through static electricity; like Figure 3 As shown, at least the portion of the spray pipe 2 located in the spray barrel 3 is made of a metal conductive material, and the electrostatic generator 4 is connected to the spray pipe 2 through an electrostatic wire 401, so that the dysprosium slurry passing through the spray pipe 2 can absorb static electricity; The spray tube 2 in the spray barrel 3 is connected to the first end of the jet tube 601, and the second end of the jet tube 601 extends out of the spray barrel 3 and is connected to the air pump 6; the high-speed airflow generated by the air pump 6 reaches the spray tube 2 through the jet tube 601, and accelerates the dysprosium slurry in the spray tube 2 to be sprayed out from the spray tube 2; a filter powder membrane cover 6011 is provided on the first end of the jet tube 601 to prevent the dysprosium powder from entering the jet tube 601; As a preferred embodiment, in order to make the dysprosium slurry sprayed from the spray pipe 2 have a wider coverage, a plurality of spray ports are opened on the spray pipe 2 located in the spray box 1, and a group of nozzle assemblies are arranged on each spray port, such as Figure 5 and Figure 6 As shown, the nozzle assembly includes: a bending shaping tube 201, a lining hose 2011 and a spray head 202; the first end of the lining hose 2011 is connected to the spray outlet, the second end of the lining hose 2011 is connected to the spray head 202, and the bending shaping tube 201 is covered on the outside of the lining hose 2011; by adjusting the bending shape of the bending shaping tube 201, the direction of spraying the dysprosium slurry from the spray head 202 can be adjusted; like Figure 2 As shown, a suction pump 7 is arranged at the bottom of the spray box 1, and the suction pump 7 is connected to the slurry storage tank 5 through a recovery pipe 501; the dysprosium powder falling into the spray box 1 will be pumped into the slurry storage tank 5 through the recovery pipe 501 by the suction pump 7, and the dysprosium powder remaining in the spray box 1 will be recovered and reused.

[0029] Example 4, based on Example 3, in Example 3, the adhesion strength between the dysprosium particles and the surface of the magnetic steel is enhanced by electrostatic adsorption; In this embodiment, while the dysprosium slurry is sprayed, magnetron sputtering is used to assist. A magnetron sputtering assembly is arranged on the spray box 1. The magnetron sputtering assembly is used to form an electric field in the spray box 1 and introduce argon gas into the spray box 1. Under the action of the electric field, electrons are accelerated to collide with argon atoms during the process of flying toward the magnetic steel, resulting in ionization of the argon atoms, generating argon ions and new electrons. The new electrons fly toward the magnetic steel, and the argon ions are accelerated to bombard the dysprosium target material under the action of the electric field. The atoms of the dysprosium target material are sputtered out, and neutral dysprosium atoms or dysprosium molecules are sputtered on the surface of the magnetic steel to form a thin film. By assisting with magnetron sputtering technology, the dysprosium thin film is deposited evenly and has stronger adhesion to the surface of the magnetic steel. In the subsequent promotion process of infiltration, the dysprosium material is prevented from peeling off from the surface of the magnetic steel due to the volatilization of the ethanol solvent, resulting in a decrease in the dysprosium infiltration rate and a low utilization rate of the raw materials, which affects the overall coercive force and temperature resistance of the magnetic steel after infiltration of dysprosium.

[0030] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0031] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and use the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A process for treating magnetic steel with dysprosium, characterized in that: The following steps are involved: S1: Magnetic steel pretreatment: cleaning and removing dirt, oxide layer and rust on the surface of the magnetic steel; and heat treatment of the magnetic steel; S2: Preparation of dysprosium powder: using chemical reduction method, using dysprosium ion solution as raw material, reacting with reducing agent to produce precipitation, and filtering and washing to obtain metal dysprosium powder; S3: Preparation of dysprosium slurry: mixing the prepared metal dysprosium powder with an ethanol solution to prepare a dysprosium slurry; the ratio of the ethanol solution to the dysprosium powder is 8-12:2-5; S4: Dysprosium slurry spraying: Dysprosium slurry is sprayed on the surface of the magnetic steel through a spray coating device; while spraying the dysprosium slurry, magnetron sputtering treatment is performed; S5: Dysprosium powder infiltration promotion treatment: the magnetic steel with the dysprosium slurry coating sprayed on the surface is subjected to dysprosium powder infiltration promotion treatment, so that the dysprosium powder particles infiltrate into the interior of the magnetic steel; The dysprosium powder infiltration-promoting treatment includes: vacuum high-temperature sintering or laser shock infiltration-promoting; S6: Post-processing: After the dysprosium-infiltrated magnetic steel is polished and repaired by a grinder and then electroplated and electrophoresed, the magnetic steel product is obtained; An organic silicon sol protective layer is coated on the surface of the prepared magnetic steel product.

2. A magnetic steel dysprosium infiltration process according to claim 1, characterized in that: The cleaning solution in S1 uses dilute nitric acid with a concentration of 3% to 5% to clean the magnetic steel to remove the oxide layer and rust; After cleaning, the surface of the magnetic steel is sandblasted and polished with diamond raw materials, and the particle size of the diamond raw materials is not less than 100 meshes; After the magnetic steel is cleaned, it is placed in a heat treatment furnace and kept at 600~800℃ for 20~40min; then the temperature is gradually increased to 900~1000℃ and kept for 300~350min; After the heat-treated magnetic steel is taken out of the furnace, it is immediately placed in cold water for water quenching cooling; The heat-treated magnetic steel is then placed in a strong magnetic field, through which the waste dysprosium powder particles in the internal cracks are cleaned out by magnetic suction.

3. The process for treating magnetic steel with dysprosium according to claim 1, characterized in that: In the preparation of the dysprosium powder, dysprosium nitrate is used as a raw material, which is dissolved in deionized water to obtain a dysprosium nitrate solution; hydrogen is introduced into the dysprosium nitrate solution, and the reaction is carried out at 1000-1300° C. for 1-3 hours; After the reaction is complete, the precipitate generated by the reaction is filtered, and the metal dysprosium powder is obtained by washing and drying.

4. The process for treating magnetic steel with dysprosium according to claim 1, characterized in that: The ethanol concentration in the preparation of the dysprosium slurry is 30%; the mixing ratio of the ethanol solution to the dysprosium powder is 10:

3.

5. The process for treating magnetic steel with dysprosium according to claim 1, characterized in that: Before spraying the dysprosium slurry, completely immerse the magnetic steel in the dysprosium slurry for 4 to 8 hours.

6. The process for treating magnetic steel with dysprosium according to claim 1, characterized in that: The specific method of vacuum high temperature sintering to promote infiltration is: putting the magnetic steel sprayed with dysprosium slurry into a metal box, and evacuating the box; putting the vacuumized metal box together with the magnetic steel into a sintering furnace; Raise the temperature in the sintering furnace to 800~1000℃ and maintain it for 4~6 hours; After high-temperature sintering, the magnetic steel is cooled to room temperature and then placed in the sintering furnace again for low-temperature tempering. The low-temperature tempering temperature is raised to 400~600℃ and kept warm for 2~4 hours. After cooling to room temperature, the dysprosium infiltration treatment is completed.

7. The process for treating magnetic steel with dysprosium according to claim 1, characterized in that: The specific method of laser shock penetration is as follows: a magnetic steel with dysprosium slurry adhered to the surface is placed in an organic glass cover, an interlayer is arranged inside the organic glass plate, and clean water is poured into the interlayer; The laser shock wave passes through the organic glass and acts on the surface of the magnetic steel. Under the action of the laser shock pulse, the dysprosium ions are promoted to penetrate into the interior of the magnetic steel.

8. A spray coating device for dysprosium infiltration of magnetic steel, characterized in that: The spray coating device comprises: a slurry storage box, a spray barrel, an air pump, an electrostatic generator, and a spray box; The dysprosium slurry is stored in the slurry storage box; The discharge port of the slurry storage box is connected to the feed pipe below the spraying cylinder through a feed pipe; A suction pump is arranged on the feed pipe; the dysprosium slurry is pumped from the slurry storage tank into the spray barrel by the suction pump; The first end of the spray pipe is arranged on the discharge port of the spray barrel, and the first end of the spray pipe extends into the spray barrel; the second end of the spray pipe extends into the spray box; The air pump is connected to the spray barrel through an air jet pipe; the air pump provides a high-pressure airflow to promote the spraying of the dysprosium slurry in the spray barrel; The electrostatic generator is used to make the dysprosium ions in the dysprosium slurry have static electricity, thereby enhancing the adsorption strength between the dysprosium ions and the magnetic steel; A magnetron sputtering assembly is arranged on the spray box; the magnetron sputtering assembly is used to form an electric field inside the spray box and to introduce argon gas into the spray box.

9. The spray coating device for dysprosium infiltration of magnetic steel according to claim 8, characterized in that: A conical cover is arranged inside the spray barrel, and the lower edge of the conical cover is connected to the inner wall of the spray barrel; the conical cover isolates an independent space inside the spray barrel; The feed pipe below the spray barrel is in communication with the independent space; The upper end opening of the conical cover is connected to the first end of the spray pipe; The air injection pipe is communicated with the material injection pipe; The portion of the spray pipe located inside the spray barrel is made of conductive metal material; The electrostatic wire of the electrostatic generator is introduced into the spray barrel and connected to the spray pipe.

10. The spray coating device for dysprosium infiltration of magnetic steel according to claim 8, characterized in that: The spray pipe is located in the spray box and has a plurality of spray outlets on its body; A set of nozzle assemblies is arranged on each of the ejection ports; The nozzle assembly comprises: a bending molding tube, a lining hose and a spray head; The first end of the lining hose is connected to the spray port, and the second end of the lining hose is connected to the spray head; the outer side of the lining hose is covered with the bending molding tube; A suction pump is arranged at the bottom of the spray box, and the suction pump is connected to the slurry storage tank through a recovery pipe.

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