Samarium-cobalt magnetic powder for high-performance injection molding of waste recycling and preparation method thereof

Abstract

The application discloses a kind of high-performance injection molding with waste recycling samarium-cobalt magnetic powder and preparation method thereof, comprising: the surface cleaning treatment of samarium-cobalt magnet waste is carried out, then solid solution treatment is carried out, aging treatment, crushing, powder, screening, obtain high-performance injection molding with samarium-cobalt magnetic powder.The method for preparing high-performance easy orientation samarium-cobalt injection magnetic powder using samarium-cobalt waste provided by the application adopts re-solid solution treatment, eliminates the original phase composition structure in magnet, and then through the optimized secondary aging treatment process, the problems of large loss of samarium-cobalt magnet breaking performance and difficult orientation of samarium-cobalt magnetic powder are overcome, so that the coercive force of the magnetic powder is obviously controlled, and is lower than 10kOe, higher remanence and magnetic energy product are obtained, and the easy orientation degree of the magnetic powder is significantly improved, which provides strong support for subsequent injection molding high-temperature orientation.The method uses waste as raw material, greatly improves the utilization rate of waste, and reduces production cost.

Description

Technical Field

[0001] This invention belongs to the field of injection molding magnetic technology, and more specifically, it relates to a high-performance samarium cobalt magnetic powder for injection molding that utilizes recycled waste materials and its preparation method. Background Technology

[0002] Samarium cobalt permanent magnets possess high magnetic properties, as well as good temperature stability and corrosion resistance, and are widely used in various important fields such as aerospace, new energy vehicles, industrial robots, computer technology, sensors, and 5G base stations.

[0003] Permanent magnets, as the most important functional materials, are increasingly widely used in the national economy and science and technology fields. Meanwhile, injection-molded magnets, due to their excellent flowability and formability, possess irreplaceable characteristics in magnets with complex, anisotropic, and thin-ring structures. Although samarium cobalt magnetic powder has good magnetic properties, its excessively high coercivity makes it difficult to orient during injection molding, and the production of anisotropic injection-molded samarium cobalt is challenging. Furthermore, research on the matching of powder particle size and the phase structure of the magnet itself is limited. Therefore, combining the performance characteristics of samarium cobalt permanent magnets and injection-molded magnets to develop high-performance samarium cobalt magnetic powder for injection molding is of significant value and importance. Summary of the Invention

[0004] This invention aims to provide a high-performance samarium cobalt magnetic powder for injection molding made from recycled waste materials and its preparation method. By using samarium cobalt waste materials to prepare high-performance, easily oriented samarium cobalt injection molding magnetic powder, high remanence and magnetic energy product are obtained, which significantly improves the orientability of the magnetic powder and provides strong support for subsequent high-temperature orientation in injection molding.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for preparing high-performance samarium cobalt magnetic powder for injection molding by recycling waste materials is provided, comprising: performing surface cleaning treatment on samarium cobalt magnet waste, followed by solution treatment, aging treatment, crushing, powdering, and sieving to obtain high-performance samarium cobalt magnetic powder for injection molding.

[0006] According to one embodiment of the present invention, the solution treatment includes: heating a surface-treated waste samarium cobalt magnet under an inert gas, wherein the solution treatment temperature is 1160-1185°C and the holding time is 2-8 hours.

[0007] According to one embodiment of the present invention, the aging treatment includes a primary aging treatment and a secondary aging treatment. The temperature of the primary aging treatment is 785-815°C, and the holding time is 4-8 hours. The temperature of the secondary aging treatment is 300-350°C, and the holding time is 3-10 hours. The cooling rate is 0.5-1°C / min.

[0008] According to one embodiment of the present invention, the aged samarium cobalt magnet is coarsely crushed to less than 10 mm in an inert atmosphere, and then medium crushed to 0.1 to 0.5 mm.

[0009] According to one embodiment of the present invention, the inert atmosphere is argon or nitrogen.

[0010] According to one embodiment of the present invention, the crushed samarium cobalt magnet is subjected to air jet milling under inert gas protection. The air jet milling pressure is 0.2 to 0.4 MPa, the sorting wheel speed is 2500 to 3000 r / min, and the particle size of the high-performance samarium cobalt magnetic powder is controlled to be 30 to 70 μm.

[0011] According to one embodiment of the present invention, the step of surface cleaning treatment of samarium cobalt magnet waste includes: cleaning and degreasing the sintered samarium cobalt magnet processing scraps or blank waste.

[0012] According to one embodiment of the present invention, the samarium cobalt magnet waste is cleaned using an ultrasonic automatic cleaning line, and after cleaning, it directly enters the drying channel for drying. During cleaning, degreasing agent and rust remover are used as cleaning agents, wherein the degreasing agent is an oil remover (inorganic salt, surfactant); and the rust remover is hydrochloric acid (HCl).

[0013] According to another aspect of the present invention, a high-performance samarium cobalt magnetic powder for injection molding based on waste recycling is also provided, which is prepared by any of the above-described methods for preparing high-performance samarium cobalt magnetic powder for injection molding based on waste recycling.

[0014] The beneficial effects of this invention are:

[0015] 1) In the method for preparing high-performance, easily oriented samarium-cobalt injection molding magnetic powder using samarium-cobalt waste of the present invention, a re-solution treatment is employed to eliminate the original phase composition and structure in the magnet. Then, an optimized two-stage aging process overcomes the problems of significant loss of performance due to breakage of samarium-cobalt magnets and the difficulty of orientation of samarium-cobalt magnetic powder. This results in significantly controlled coercivity of the magnetic powder, all below 10 kOe, achieving high remanence and energy product, and significantly improving the orientability of the magnetic powder, providing strong support for subsequent high-temperature orientation in injection molding. Furthermore, this method uses waste as raw material, greatly improving waste utilization and reducing production costs. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0017] This invention provides a method for preparing high-performance samarium cobalt magnetic powder for injection molding by recycling waste materials, comprising: surface cleaning treatment of samarium cobalt magnet waste, followed by solid solution treatment, aging treatment, crushing, powdering, and sieving to obtain high-performance samarium cobalt magnetic powder for injection molding.

[0018] According to the present invention, the method for preparing high-performance samarium cobalt magnetic powder for injection molding from recycled waste includes the following steps:

[0019] Step 1: Waste cleaning

[0020] Surface cleaning treatment of samarium-cobalt magnet waste: The processing scraps or blanks of sintered samarium-cobalt magnets are cleaned to remove oil and rust. During cleaning, degreasing agents and rust removers are added as cleaning agents. The degreasing agent is an oil remover (inorganic salt, surfactant), and the rust remover is hydrochloric acid (HCl). Preferably, an ultrasonic automatic cleaning line is used to clean the samarium-cobalt magnet waste, and after cleaning, it directly enters the drying channel for drying.

[0021] Step 2: Solution treatment

[0022] The cleaned samarium-cobalt waste was heated to 1160–1185°C under an inert gas atmosphere and held for 2–8 hours for solution treatment. Finally, it was rapidly cooled to room temperature to obtain a samarium-cobalt magnet blank, which mainly consists of an unstable 1:7 phase and a small amount of impurity phases.

[0023] Step 3: Time-sensitive processing

[0024] The aging treatment includes a primary aging treatment and a secondary aging treatment. The sintered samarium cobalt magnet blank is first subjected to a primary aging treatment under inert gas protection at a temperature of 785-815℃ for 4-8 hours. Then, the temperature is reduced to 300-350℃ at a rate of 0.5-1℃ / min for a secondary aging treatment, which is held for 3-10 hours. Finally, it is air-cooled or cooled to room temperature in the furnace.

[0025] The purpose of resolution treatment after surface cleaning of waste samarium-cobalt magnets is to eliminate the original phase composition and structure within the magnets. The presence of the original 2:17 and 1:5 phase structures gives the magnets high coercivity, increasing the difficulty of orientation during subsequent injection molding, leading to unsaturated orientation and performance loss. By eliminating the internal phase composition of the magnets through resolution treatment, and then applying an optimized two-stage aging process, the coercivity of the magnets is controlled while achieving high remanence and magnetic energy product, significantly improving the orientation ease of the magnetic powder.

[0026] Step 4: Crushing Process

[0027] The samarium cobalt scrap or waste magnetic steel ingots obtained after secondary aging treatment are first subjected to primary crushing, and then to secondary crushing. The samarium cobalt magnetic powder after secondary crushing is easily oxidized in the air, causing a sharp decrease in magnetic properties. Therefore, inert gas protection is used throughout the crushing process.

[0028] The obtained alloy ingots are initially crushed to approximately 10 mm or less, and then further crushed to 0.1–0.5 mm. Considering that the fracture mechanism of samarium cobalt is mainly transgranular fracture, this invention ensures the integrity of the main phase of samarium cobalt magnetic powder by strictly controlling its morphology and particle size. A combination of large particle size and low grinding pressure processes makes the powder more spherical, reducing the formation of sharp edges and maintaining the relative integrity of the main phase. This allows the magnetic domains to easily deflect during the high-temperature injection molding stage, thus ensuring high magnetic performance.

[0029] Considering that samarium cobalt magnetic powder is easily oxidized in air after intermediate crushing, resulting in a sharp decrease in magnetic properties, inert gases such as argon or nitrogen are used for protection throughout the crushing process. The preferred inert gas is argon or nitrogen, but it can also be other gases, as long as they can prevent or slow down oxidation.

[0030] Step 5: Powdering Process

[0031] The obtained coarse powder was milled into samarium cobalt powder under inert gas protection by air jet milling. The air jet mill pressure was 0.2-0.4 MPa, the sorting wheel speed was 2500-3000 r / min, and the magnetic powder particle size was controlled to be 30-70 μm. A relatively fine powder particle size is beneficial to the granulation process of injection molding granules, but too low a particle size will increase the risk of oxidation and greatly damage the main phase structure, resulting in a sharp decline in magnetic properties. Therefore, controlling the magnetic powder particle size is very important for obtaining high-performance samarium cobalt magnetic powder with consistent and stable performance.

[0032] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0033] Example 1

[0034] The specific preparation steps for preparing high-performance samarium-cobalt magnetic powder for injection molding using samarium-cobalt magnet waste are as follows:

[0035] Step 1: Waste cleaning

[0036] The samarium-cobalt waste was cleaned for 30 minutes using an ultrasonic automatic cleaning line. The cleaning agents mainly included degreasing agents, hydrochloric acid degreasing agents, and rust removers. After cleaning, the waste was directly sent to the drying channel and dried at 150°C for 2 hours.

[0037] Step 2: Solution treatment

[0038] The cleaned samarium-cobalt waste was heated to 1175°C under an inert gas atmosphere and held for 4 hours. Finally, it was rapidly cooled to room temperature to obtain samarium-cobalt magnet blanks.

[0039] Step 3: Time-sensitive processing

[0040] The sintered samarium cobalt magnet blanks were subjected to a first-stage aging treatment at 815℃ for 4 hours under Ar inert gas protection. Then, the temperature was reduced to 350℃ at a rate of 0.7℃ / min for a second-stage aging treatment, which was held for 10 hours. Finally, the blanks were air-cooled or cooled to room temperature in the furnace.

[0041] Step 4: Crushing Process

[0042] The samarium-cobalt scraps or waste magnetic steel ingots obtained after aging treatment are first subjected to primary crushing, and then to secondary crushing, which is then crushed to 0.5mm.

[0043] Step 5: Powdering Process

[0044] The obtained coarse powder was milled into samarium cobalt powder under inert gas protection using an air jet mill. The air jet mill pressure was 0.4 MPa, the sorting wheel speed was 3000 r / min, and the magnetic powder particle size was controlled to be 30 μm. The magnetic properties of the magnetic powder were tested using a VSM (vibrating sample magnetometer), and the data are shown in Table 1.

[0045] Example 2

[0046] Step 1: Waste cleaning

[0047] The samarium-cobalt waste was cleaned for 30 minutes using an ultrasonic automatic cleaning line. The cleaning agents mainly included degreasing agent (inorganic salt and surfactant) and rust remover hydrochloric acid (HCl). After cleaning, the waste was directly sent to the drying channel for drying at 150°C.

[0048] Step 2: Solution treatment

[0049] The cleaned samarium-cobalt waste was heated to 1185°C under an inert gas atmosphere and held at that temperature for 2 hours. Then it was rapidly cooled to room temperature to obtain samarium-cobalt magnet blanks.

[0050] Step 3: Time-sensitive processing

[0051] The sintered samarium cobalt magnet blanks were subjected to a first-stage aging treatment at 815℃ for 5 hours under Ar inert gas protection. Then, the temperature was reduced to 350℃ at a rate of 0.7℃ / min for a second-stage aging treatment, which was held for 10 hours. Finally, the blanks were air-cooled or cooled to room temperature in the furnace.

[0052] Step 4: Crushing Process

[0053] The samarium-cobalt scraps or waste magnetic steel ingots obtained after aging treatment are first subjected to primary crushing, and then to secondary crushing, which is then crushed to 0.5mm.

[0054] Step 5: Powdering Process

[0055] The obtained coarse powder was milled into samarium cobalt powder under inert gas protection using an air jet mill. The air jet mill pressure was 0.4 MPa, the sorting wheel speed was 3000 r / min, and the magnetic powder particle size was controlled to be 40 μm. The magnetic properties of the magnetic powder were tested using a VSM (vibrating sample magnetometer), and the data are shown in Table 1.

[0056] Example 3

[0057] Step 1: Waste cleaning

[0058] Samarium cobalt waste was cleaned for 30 minutes using an ultrasonic automatic cleaning line. The cleaning agents mainly included degreasing agents (inorganic salts, surfactants), rust removers (hydrochloric acid, HCl), etc. After cleaning, the waste was directly sent to the drying channel and dried at 140°C for 2 hours.

[0059] Step 2: Solution treatment

[0060] The cleaned samarium-cobalt waste was heated to 1160°C under an inert gas atmosphere and held for 8 hours, then rapidly cooled to room temperature to obtain samarium-cobalt magnet blanks.

[0061] Step 3: Time-sensitive processing

[0062] The sintered samarium cobalt magnet blank was placed under the protection of inert gas Ar. The first-stage aging treatment temperature was 785℃ and held for 8 hours. Then, the temperature was reduced to 300℃ at a rate of 1.0℃ / min for the second-stage aging treatment and held for 3 hours. Finally, it was air-cooled or cooled to room temperature in the furnace.

[0063] Step 4: Crushing Process

[0064] The samarium-cobalt scraps or waste magnetic steel ingots obtained after aging treatment are first subjected to primary crushing, and then to secondary crushing, which is then crushed to 0.1mm.

[0065] Step 5: Powdering Process

[0066] The obtained coarse powder was milled into samarium cobalt powder under inert gas protection using an air jet mill. The air jet mill pressure was 0.2 MPa, the sorting wheel speed was 2500 r / min, and the magnetic powder particle size was controlled to be 70 μm. The magnetic properties of the magnetic powder were tested using a VSM (vibrating sample magnetometer), and the data are shown in Table 1.

[0067] Comparative Example 1

[0068] Steps one and two are the same as in Example 1.

[0069] Step 3: Time-sensitive processing

[0070] The sintered samarium cobalt magnet blanks were subjected to a first-stage aging treatment at 850°C for 10 hours under inert gas protection. Then, the temperature was reduced to 400°C at a rate of 0.7°C / min for a second-stage aging treatment, which was held for 10 hours. Finally, the blanks were air-cooled or cooled in the furnace to room temperature.

[0071] Step 4: Crushing Process

[0072] The samarium-cobalt scraps or waste magnetic steel ingots obtained after aging treatment are first subjected to primary crushing, and then to secondary crushing, which is then crushed to 0.5mm.

[0073] Step 5: Powdering Process

[0074] The obtained coarse powder was milled into samarium cobalt powder under inert gas protection using an air jet mill. The air jet mill pressure was 0.4 MPa, the sorting wheel speed was 3000 r / min, and the magnetic powder particle size was controlled to be 4.5 μm. The particle size of this powder is similar to that of sintered samarium cobalt magnetic powder. The magnetic properties of the magnetic powder were tested using a VSM (vibrating sample magnetometer), and the data are shown in Table 1.

[0075] Comparative Example 2

[0076] Steps one and two are the same as in Example 2.

[0077] Step 3: Time-sensitive processing

[0078] The sintered samarium cobalt magnet blanks were subjected to a first-stage aging treatment at 840℃ for 10 hours under inert gas protection. Then, the temperature was reduced to 450℃ at a rate of 0.7℃ / min for a second-stage aging treatment, which was held for 10 hours. Finally, the blanks were air-cooled or cooled in the furnace to room temperature.

[0079] Step 4: Crushing Process

[0080] The samarium-cobalt scraps or waste magnetic steel ingots obtained after aging treatment are first subjected to primary crushing, and then to secondary crushing, which reduces the size to 0.4mm.

[0081] Step 5: Powdering Process

[0082] The obtained coarse powder was milled into samarium cobalt powder under inert gas protection using an air jet mill. The air jet mill pressure was 0.4 MPa, the sorting wheel speed was 3000 r / min, and the magnetic powder particle size was controlled to be 4.2 μm. The particle size of this powder is similar to that of sintered samarium cobalt magnetic powder. The magnetic properties of the magnetic powder were tested using a VSM (vibrating sample magnetometer), and the data are shown in Table 1.

[0083] Comparative Example 3

[0084] Steps one and two are the same as in Example 3.

[0085] Step 3: Time-sensitive processing

[0086] The sintered samarium cobalt magnet blanks were subjected to a first-stage aging treatment at 830°C for 15 hours under inert gas protection. Then, the temperature was reduced to 400°C at a rate of 0.7°C / min for a second-stage aging treatment, which was held for 10 hours. Finally, the blanks were air-cooled or cooled to room temperature in the furnace.

[0087] Step 4: Crushing Process

[0088] The samarium-cobalt scraps or waste magnetic steel ingots obtained after aging treatment are first subjected to primary crushing, and then to secondary crushing, which reduces the size to 0.3mm.

[0089] Step 5: Powdering Process

[0090] The obtained coarse powder was milled into samarium cobalt powder under inert gas protection using an air jet mill. The air jet mill pressure was 0.4 MPa, the sorting wheel speed was 3000 r / min, and the magnetic powder particle size was controlled to be 4.0 μm. The particle size of this powder is similar to that of sintered samarium cobalt magnetic powder. The magnetic properties of the magnetic powder were tested using a VSM (vibrating sample magnetometer), and the data are shown in Table 1.

[0091] Table 1. Magnetic property test results of the examples and comparative examples.

[0092]

[0093]

[0094] A comparison of the magnetic properties of the samarium cobalt magnetic powders prepared in Examples 1-3 and Comparative Examples 1-3 shows that when the optimized two-stage aging process of this invention is used, the coercivity of the magnetic powder can be significantly controlled, all below 10 kOe, providing strong support for subsequent high-temperature orientation in injection molding. In contrast, the coercivity of Comparative Examples 1-3 is relatively high, making orientation difficult, especially for injection-molded magnets with complex structures and small dimensions, which greatly limits the application of injection-molded samarium cobalt.

[0095] Meanwhile, the optimized powder preparation process employed in this invention effectively preserves the original samarium-cobalt main phase, resulting in significantly higher magnetic energy products compared to Comparative Examples 1-3. This is primarily because in Comparative Examples 1-3, the intense collisions of numerous samarium-cobalt particles during powder preparation led to extensive transgranular fracture of the main phase, drastically reducing the effective main phase for providing magnetic properties. This invention, through rational optimization of the powder particle size and dimensional control process, not only ensures the uniformity of subsequent granulation but also preserves the high magnetic properties.

[0096] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-performance samarium cobalt magnetic powder for injection molding using recycled waste materials, characterized in that, include: The samarium cobalt magnet waste is surface cleaned, then subjected to solution treatment, aging treatment, crushing, powdering, and sieving to obtain high-performance samarium cobalt magnetic powder for injection molding. The aging treatment includes a primary aging treatment and a secondary aging treatment. The temperature of the primary aging treatment is 785–815℃, and the holding time is 4–8 hours. The temperature of the secondary aging treatment is 300–350℃, and the holding time is 3–10 hours. The cooling rate is 0.5–1℃ / min.

2. The preparation method according to claim 1, characterized in that, The solution treatment includes: heating the surface-treated waste samarium-cobalt magnet under an inert gas atmosphere, wherein the solution treatment temperature is 1160–1185°C and the holding time is 2–8 hours.

3. The preparation method according to claim 2, characterized in that, The aged samarium-cobalt magnets were coarsely crushed to below 10 mm in an inert atmosphere, and then medium crushed to 0.1–0.5 mm.

4. The preparation method according to claim 3, characterized in that, The inert atmosphere is argon or nitrogen.

5. The preparation method according to claim 1, characterized in that, The crushed samarium cobalt magnets were ground into powder by air jet milling under inert gas protection. The air jet mill pressure was 0.2-0.4 MPa, the sorting wheel speed was 2500-3000 r / min, and the particle size of the high-performance samarium cobalt magnetic powder was controlled to be 30-70 μm.

6. The preparation method according to claim 1, characterized in that, The steps for surface cleaning of samarium cobalt magnet waste include: cleaning and degreasing the sintered samarium cobalt magnet processing scraps or blank waste.

7. The preparation method according to claim 6, characterized in that, The samarium cobalt magnet waste is cleaned using an ultrasonic automatic cleaning line, and then directly enters the drying channel for drying. During cleaning, degreasing agent and rust remover are used as cleaning agents, wherein the degreasing agent is an oil remover and the rust remover is hydrochloric acid.

8. A high-performance samarium cobalt magnetic powder for injection molding using recycled waste materials, characterized in that, It is obtained by the preparation method of high-performance samarium cobalt magnetic powder for injection molding based on waste recycling as described in any one of claims 1 to 7.

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