A samarium cobalt permanent magnet material and its preparation method

Abstract

The present application provides a samarium cobalt permanent magnet material and a preparation method thereof. The preparation method comprises: step S1, according to the nominal composition Sm u Co v Cu w Fe x Zr y (Gd 0.5 Er 0.5 ) 0.5‑z Dy z The invention relates to a method for preparing a mixture by mixing ingredients; step S2, smelting and casting the mixture under an inert atmosphere to obtain an ingot; step S3, crushing the ingot to obtain alloy powder; step S4, orienting and forming the alloy powder and pressing the alloy powder to obtain a green body; step S5, sintering and solution treating the green body to obtain a samarium-cobalt solid solution magnet; step S6, providing a metal coating layer on the surface of the samarium-cobalt solid solution magnet and performing an aging treatment to obtain a samarium-cobalt permanent magnet material. Heavy rare earth elements and medium-heavy rare earth elements (Er) are added to the raw materials to compensate for the negative temperature coefficient of residual magnetism. At the same time, through the coordination of the above steps, especially the aging treatment after coating the metal coating layer, the microstructure of the samarium-cobalt magnet is regulated, so that the samarium-cobalt permanent magnet material has an excellent low temperature coefficient of residual magnetism, a maximum operating temperature of 500°C, and excellent initial magnetic properties at room temperature.

Description

Technical Field

[0001] The present application relates to the field of rare earth permanent magnet materials, and in particular to a samarium cobalt permanent magnet material and a preparation method thereof. Background Art

[0002] As the second generation of rare earth permanent magnet materials, 2:17 sintered samarium cobalt permanent magnet materials are widely used in rail transportation, satellite communications, aerospace and other fields due to their excellent high temperature stability, corrosion resistance and oxidation resistance.

[0003] Currently, 2:17 sintered SmCo permanent magnets are primarily classified into three categories based on their properties: high-performance SmCo magnets, low temperature coefficient magnets, and high-temperature magnets. However, in some specialized environments, low or severe degradation of magnetic properties persists at high temperatures, particularly in remanence. The remanence of 2:17 sintered SmCo permanent magnets is extremely sensitive to temperature and exhibits a nonlinear decrease. The current solution is to add a certain amount of rare earth elements to improve this. However, this addition can lead to a decrease in initial magnetic performance or maintain a low remanence temperature coefficient at only 250°C, with a sharp drop in magnetic properties above 300°C. Summary of the Invention

[0004] The present application provides a samarium cobalt permanent magnet material and a preparation method thereof, so as to solve the problem of insufficient high-temperature magnetic properties of existing samarium cobalt permanent magnet materials.

[0005] The first aspect of the present application provides a method for preparing a samarium-cobalt permanent magnet material, the method comprising: step S1, preparing a samarium-cobalt permanent magnet material according to a nominal composition of Sm u Co v Cu w Fe x Zr y (Gd 0.5 Er 0.5 ) 0.5-z Dy z The process comprises the following steps: preparing ingredients to obtain a mixture; wherein, 0.5≤u≤1.5, 4.5≤v≤5.5, 0.45≤w≤0.85, 1.4≤x≤2.4, 0.14≤y≤0.24, 0.1≤Z≤0.4, and u+v+w+x+y=7.5; step S2, smelting and casting the mixture under an inert atmosphere to obtain an ingot; step S3, crushing the ingot to obtain alloy powder; step S4, performing orientation molding and compacting on the alloy powder to obtain a green compact; step S5, sintering and solution treating the green compact to obtain a samarium cobalt solid solution magnet; and step S6, providing a metal coating layer on the surface of the samarium cobalt solid solution magnet and performing aging treatment to obtain a samarium cobalt permanent magnet material.

[0006] Furthermore, the above-mentioned step S6 includes: placing the samarium cobalt solid solution magnet in a metal box and sealing it to obtain a sealed body, a copper foil is provided on the inner wall of the metal box, the samarium cobalt solid solution magnet is bonded to the copper foil in the metal box, and the thickness of the copper foil is preferably 75 to 100 μm; placing the sealed body in a furnace cavity in an aging furnace for aging treatment to obtain a samarium cobalt permanent magnet material.

[0007] Furthermore, the aging treatment includes: step A, heating the aging furnace to 800-900°C, filling the furnace chamber with protective gas, and keeping the temperature at 800-900°C for 5-30 hours to perform a first-stage aging treatment; step B, cooling the aging furnace to 300-500°C at a cooling rate of 0.65-0.85°C / min and keeping the temperature for 5-30 hours to perform a second-stage aging treatment; step C, cooling the aging furnace to 200-300°C at a cooling rate of 5-15°C / min to obtain a cooled magnet; step D, quenching the cooled magnet to obtain a samarium cobalt permanent magnet material.

[0008] Furthermore, the temperature of the first-stage aging treatment is 820-840° C. and the time is 15-20 hours; the time of the second-stage aging treatment is 5-15 hours.

[0009] Furthermore, the metal box is made of a ductile metal or alloy material having a melting point higher than the aging treatment temperature. The metal box is preferably any one of an iron box, a tungsten box, and a lead box. The wall thickness of the metal box is preferably 0.3 to 0.5 mm.

[0010] Furthermore, the above step C includes subjecting the aging furnace to cyclic filling and discharging of gas and air cooling treatment so that the aging furnace is cooled to 200-300° C. at a cooling rate of 5-15° C. / min to obtain a cooled magnet.

[0011] Furthermore, the above step D includes placing the cooling magnet in a cooling liquid for rapid cooling, and the cooling rate of the rapid cooling treatment is 200-300°C / min.

[0012] Furthermore, the alloy powder has a particle size of 3.5 to 4.5 μm.

[0013] Furthermore, the alloy powder is mixed with a lubricant before the alloy powder is subjected to orientation molding. Preferably, the mass of the lubricant is 0.25 to 0.5‰ of the mass of the alloy powder.

[0014] Furthermore, the above-mentioned step S5 includes: in a vacuum environment, keeping the green body at 200-450°C for 1-3 hours for primary exhaust treatment; after completing the primary exhaust treatment, heating the green body to 800-950°C and keeping it for 1-3 hours for secondary exhaust treatment; after completing the secondary exhaust treatment, using argon as a protective gas, heating the green body to 1150-1200°C and keeping it for 1-2 hours for pre-sintering treatment, then heating it to 1190-1215°C at a heating rate of 3-8°C / min and keeping it for 1-3 hours for sintering treatment, then cooling it to 1150-1200°C for 2-4 hours of solid solution treatment, and finally air-cooling it to room temperature to obtain a samarium cobalt solid solution magnet, and the preferred air cooling rate is 5-15°C / min.

[0015] Furthermore, the temperature of the above-mentioned first-level exhaust treatment is 200-400°C and the time is 1.5-2 hours; the temperature of the second-level exhaust treatment is 850-900°C and the time is 1.5-2 hours; the temperature of the sintering treatment is 1200-1205°C and the time is 1.5-2 hours.

[0016] According to another aspect of the present application, a samarium cobalt permanent magnet material obtained by any of the above preparation methods is provided.

[0017] The preparation method of the present application adds heavy rare earth elements and medium-heavy rare earth element Er to the raw materials to compensate for the negative temperature coefficient of remanence. At the same time, through the coordination of the above steps, especially the aging treatment after coating with the metal coating layer, the microstructure of the samarium cobalt magnet is regulated, so that the samarium cobalt permanent magnet material has an excellent low temperature coefficient of remanence, a maximum operating temperature of 500°C, and excellent initial magnetic properties at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the following briefly describes the drawings required for use in the embodiments of this application. Obviously, the drawings described below are merely examples of the present application, and those skilled in the art can derive other drawings based on the drawings without inventive effort. The following drawings were drawn using Origin after obtaining data from an ultra-high temperature measuring instrument.

[0019] Figure 1 The demagnetization curve of the low temperature coefficient sintered samarium cobalt magnet obtained in Example 1 in the range of 20 to 300°C is shown;

[0020] Figure 2 The demagnetization curve of the low temperature coefficient sintered samarium cobalt magnet obtained in Example 2 in the range of 20 to 300°C is shown;

[0021] Figure 3The demagnetization curve of the low temperature coefficient sintered samarium cobalt magnet obtained in Example 3 is shown in the range of 20 to 300°C. DETAILED DESCRIPTION

[0022] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0023] As analyzed in the background art, the high-temperature magnetic properties of the existing samarium cobalt permanent magnet material are insufficient. In order to solve the above problem, the present application provides a samarium cobalt permanent magnet material and a preparation method thereof.

[0024] In a typical embodiment of the present application, a method for preparing a samarium cobalt permanent magnet material is provided. The method comprises: step S1, preparing a samarium cobalt permanent magnet material according to the nominal composition Sm u Co v Cu w Fe x Zr y (Gd 0.5 Er 0.5 ) 0.5-z Dy z The process comprises the following steps: preparing ingredients to obtain a mixture; wherein, 0.5≤u≤1.5, 4.5≤v≤5.5, 0.45≤w≤0.85, 1.4≤x≤2.4, 0.14≤y≤0.24, 0.1≤Z≤0.4, and u+v+w+x+y=7.5; step S2, smelting and casting the mixture under an inert atmosphere to obtain an ingot; step S3, crushing the ingot to obtain alloy powder; step S4, performing orientation molding and compacting on the alloy powder to obtain a green compact; step S5, sintering and solution treating the green compact to obtain a samarium cobalt solid solution magnet; and step S6, providing a metal coating layer on the surface of the samarium cobalt solid solution magnet and performing aging treatment to obtain a samarium cobalt permanent magnet material.

[0025] The preparation method of the present application adds heavy rare earth elements and medium-heavy rare earth element Er to the raw materials to compensate for the negative temperature coefficient of remanence. At the same time, through the coordination of the above steps, especially the aging treatment after coating with the metal coating layer, the microstructure of the samarium cobalt magnet is regulated, so that the samarium cobalt permanent magnet material has an excellent low temperature coefficient of remanence, a maximum operating temperature of 500°C, and excellent initial magnetic properties at room temperature.

[0026] The above-mentioned samarium cobalt permanent magnet material is a sintered magnet.

[0027] In some embodiments, the above step S6 includes: placing the samarium cobalt solid solution magnet in a metal box for sealing to obtain a sealed body, wherein a copper foil is provided on the inner wall of the metal box, and the samarium cobalt solid solution magnet is bonded to the copper foil in the metal box, and the thickness of the copper foil is preferably 75 to 100 μm; placing the sealed body in a furnace cavity of an aging furnace for aging treatment to obtain a samarium cobalt permanent magnet material.

[0028] The samarium cobalt solid solution magnet is placed in a metal box and sealed before undergoing aging treatment. This avoids the violent oxidation reaction that occurs when the magnet is directly exposed to air at high temperature when cooling after aging treatment. The use of copper foil can be more conducive to the fitting and sealing of the magnet. In addition, during the aging treatment, the Cu element is enriched in the cell wall to form an Sm(Co, Cu)5 cell wall phase, which pins the domain wall and thus improves the coercive force of the magnet.

[0029] By adjusting the thickness of the copper foil as described above, the wrapping, thermal conductivity and heat dissipation of the samarium cobalt solid solution magnet can be enhanced, making it easier to form finer grains.

[0030] When using a metal box to seal the samarium cobalt solid solution magnet, a metal box of corresponding size can be designed according to the size of the samarium cobalt solid solution magnet, copper foil of corresponding size is affixed to the inner wall of the metal box, and a tightly sealed metal cover is left. Then, the samarium cobalt solid solution magnet is placed in the metal box and covered with the metal cover.

[0031] In order to improve the aging treatment effect, in some embodiments, the aging treatment includes: step A, heating the aging furnace to 800-900° C., filling the furnace chamber with protective gas, and keeping the temperature at 800-900° C. for 5-30 hours to perform a first-stage aging treatment; step B, cooling the aging furnace to 300-500° C. at a cooling rate of 0.65-0.85° C. / min and keeping the temperature for 5-30 hours to perform a second-stage aging treatment; step C, cooling the aging furnace to 200-300° C. at a cooling rate of 5-15° C. / min to obtain a cooled magnet; and step D, quenching the cooled magnet to obtain a samarium cobalt permanent magnet material.

[0032] The first-stage aging treatment regulates and optimizes the distribution of added medium and heavy rare earth elements within the magnet and the diffusion of Cu atoms from the copper foil into the magnet. The second-stage aging treatment opens diffusion channels for Cu within the magnet, enriching it in the cell walls. There, it forms a Cu-rich, Fe-poor, and Zr-poor hexagonal Sm(Co, Cu)5 cell wall phase with samarium and cobalt, maintaining a coherent relationship with the main phase within the cell. This 1:5 cell wall phase of Sm(Co, Cu)5 pins domain walls, resulting in a high intrinsic coercivity. Increasing the Cu content promotes the precipitation of the 1:5 phase, which in turn increases the coercivity.

[0033] At the same time, the above-mentioned steps C and D are combined to adopt a rapid heat conduction + rapid cooling method to cool the magnet, which strengthens the formation of the unit cell boundary phase in the magnet, thereby obtaining a samarium cobalt permanent magnet material with excellent remanence and low temperature coefficient. For example, at a high temperature of 300°C, the remanence temperature coefficient can be maintained at -0.035% to -0.020% while ensuring excellent magnetic properties, which is far superior to other magnets in the prior art. In particular, it still has working magnetic properties at 500°C.

[0034] In some embodiments, the temperature of the first aging treatment is preferably 820-840° C. and the time is preferably 15-20 hours; and the time of the second aging treatment is preferably 5-15 hours.

[0035] The above-mentioned metal box is mainly used to physically isolate the samarium cobalt solid solution magnet from external substances. In some embodiments, the material of the above-mentioned metal box is a metal or alloy material with a melting point higher than the aging treatment temperature and ductility, thereby better ensuring the protective effect of the metal box on the samarium cobalt solid solution magnet during the aging treatment process; the metal box is preferably any one of an iron box, a tungsten box, and a lead box, and the wall thickness of the metal box is preferably 0.3 to 0.5 mm, so as to achieve both isolation and avoid affecting heat dissipation.

[0036] There are many cooling methods for the above step C. In order to better control the cooling rate, in some embodiments, the above step C includes subjecting the aging furnace to cyclic filling and discharging of gas and air cooling so that the aging furnace is cooled to 200-300°C at a cooling rate of 5-15°C / min to obtain a cooled magnet.

[0037] The cooling method in step D can be various. To better control the cooling rate, in some embodiments, step D includes placing the cooled magnet in a coolant for rapid cooling at a cooling rate of 200-300°C / min. The coolant used in this application includes, but is not limited to, any one or more of water and oil.

[0038] In order to improve the mixing uniformity of the alloy, the particle size of the alloy powder is preferably 3.5 to 4.5 μm. The above step S3 can be performed by mechanically crushing and medium crushing the ingot in an oxygen-free environment or under the protection of an inert atmosphere, and finally using a jet mill to obtain the above alloy powder. The inert atmosphere is an argon atmosphere.

[0039] In some embodiments, the alloy powder is mixed with a lubricant before orientation molding. The lubricant preferably accounts for 0.25-0.5‰ of the alloy powder mass. The alloy powder and lubricant are preferably mixed in a universal motion mixer for 1-3 hours. This further improves the orientation of the various elements in the alloy powder during orientation molding. Lubricants used in this application include, but are not limited to, zinc stearate.

[0040] The green compact can be produced by any of the methods commonly used in the art, namely, cold isostatic pressing, die pressing, and three-dimensional pressing.

[0041] The sintering and solution treatment of the present application can refer to the existing technology. In order to further control the grain size and element uniformity, in some embodiments, the above-mentioned step S5 includes: in a vacuum environment, keeping the green body at 200-450°C for 1-3 hours for primary exhaust treatment; after completing the primary exhaust treatment, heating the green body to 800-950°C and keeping it for 1-3 hours for secondary exhaust treatment; after completing the secondary exhaust treatment, using argon as a protective gas, heating the green body to 1150-1200°C and keeping it for 1-2 hours for pre-sintering treatment, then heating it to 1190-1215°C at a heating rate of 3-8°C / min and keeping it for 1-3 hours for sintering treatment, then cooling it to 1150-1200°C for 2-4 hours of solid solution treatment, and finally air cooling it to room temperature to obtain a samarium cobalt solid solution magnet. The preferred cooling rate of air cooling is 5-15°C / min.

[0042] In some embodiments, the higher the vacuum degree of the vacuum environment, the better the exhaust effect, but the higher the construction cost. Therefore, preferably the vacuum pressure of the vacuum environment is 1×10 -3 ~5×10 -3 pa.

[0043] It is further preferred that the temperature of the above-mentioned first-level exhaust treatment is 200-400°C and the time is 1.5-2 hours; the temperature of the second-level exhaust treatment is 850-900°C and the time is 1.5-2 hours; the temperature of the sintering treatment is 1200-1205°C and the time is 1.5-2 hours.

[0044] The protective gas used in the above preparation method includes but is not limited to argon.

[0045] In another typical embodiment of the present application, a samarium cobalt permanent magnet material obtained by any of the above-mentioned preparation methods is provided. The preparation method of the present application adds heavy rare earth elements and medium-heavy rare earth element Er to the raw materials to compensate for the negative temperature coefficient of remanence. At the same time, through the coordination of the above-mentioned steps, especially the aging treatment of the coating of the metal coating layer, the microstructure of the samarium cobalt magnet is regulated, so that the samarium cobalt permanent magnet material has an excellent low temperature coefficient of remanence, a maximum operating temperature of 500°C, and excellent initial magnetic properties at room temperature.

[0046] The beneficial effects of the present application will be further illustrated below with reference to examples and comparative examples.

[0047] Example 1

[0048] Step 1: According to the nominal composition Sm 0.71 Co 4.55 Cu 0.46 Fe1.58 Zr 0.2 Gd 0.2 Er 0.2 Dy 0.1 The alloy is placed in a vacuum induction melting furnace, wherein Sm is placed at the bottom of the pot to reduce the volatilization of Sm during the melting process. The alloy is first vacuumed and then filled with inert gas, and then melted and cast to obtain an alloy ingot.

[0049] Step 2: The ingot is mechanically crushed and medium-crushed in an oxygen-free environment, and finally jet milled to obtain alloy fine powder with an average particle size of 4.30 μm;

[0050] Step 3: Add 0.3‰ of the total weight of the alloy fine powder to the lubricant zinc stearate, and mix the powder for 2 hours using a universal motion mixer to obtain a fine powder with uniform tissue distribution;

[0051] Step 4: Orienting and molding the fine powder in an inert gas atmosphere and a magnetic field to directly obtain a samarium-cobalt magnet green body; or cold isostatic pressing is performed in a fluid after orientation molding to obtain a samarium-cobalt magnet green body;

[0052] Step 5: Place the green billet on a 3×10 -3 Heat treatment is carried out in a high vacuum environment of pa. First, the temperature is kept at 400℃ for 2 hours for primary exhaust treatment. After the primary exhaust treatment is completed, the temperature is raised to 900℃ and kept for 2 hours for secondary exhaust treatment. After the secondary exhaust treatment is completed, the temperature is raised to 1185℃ and kept for 2 hours for pre-sintering treatment. At this time, argon is filled as a protective gas. Then the temperature is raised to 1205℃ at a heating rate of 5℃ / min and kept for 2 hours for sintering treatment. Then, it is cooled to 1160℃ at a rate of 0.7℃ / min for 2 hours for solid solution treatment, and finally quickly cooled to room temperature at a rate of 10℃ / min.

[0053] Step 6: After sintering is completed, the laminating and coating treatment is carried out. According to the size of the sintered samarium cobalt magnet, a thin-skin iron box of corresponding size is designed, with a thickness of 0.3mm. A copper foil of corresponding size is pasted on the inner wall of the thin-skin iron box, with a thickness of 100μm, and a tightly sealed iron cover is left. Then the samarium cobalt magnet is placed in the thin-skin iron box and covered with the iron cover.

[0054] Step 7: After the lamination and coating treatment is completed, aging treatment is carried out. First, the temperature is raised to 830℃, argon is filled as a protective gas, and then the temperature is kept for 20 hours for the first aging treatment. After completion, the temperature is cooled to 400℃ at a cooling rate of 0.7℃ / min and kept for 20 hours for the second aging treatment. After completion, a circulating gas extraction + air cooling treatment is carried out for rapid cooling. The temperature is reduced to 300℃ at a rate of 15℃ / min. The thin iron box containing the samarium cobalt magnet is taken out and placed in water for rapid cooling at 240℃ / min. Finally, a sintered samarium cobalt magnet with low residual temperature coefficient is obtained.

[0055] The ultra-high temperature measuring instrument uses an electromagnet to magnetize the sample and implements a quasi-static scanning method. The purpose is to slowly increase the magnetizing current during the measurement process to make the sting change a constant, thereby avoiding the generation of eddy currents and the phase angle between the magnetic field and the magnetic polarization intensity during the measurement process. The measuring device uses data acquisition technology to measure the hysteresis loop of the material, and then calculates the magnetic properties of the prepared sintered samarium cobalt magnet based on the definition: at 20°C, the remanence B r =9.64kGs, magnetic energy product (BH) max =23.02MGOe, intrinsic coercive force H cj =26.58kOe; at 300℃, remanence B r =9.05kGs, magnetic energy product (BH) max =18.72MGOe, intrinsic coercive force H cj =10.02kOe, where the remanence temperature coefficient is -0.021%.

[0056] Example 2:

[0057] Step 1: According to the nominal composition Sm 0.7 Co 4.55 Cu 0.55 Fe 1.55 Zr 0.15 Gd 0.15 Er 0.15 Dy 0.2 The alloy is placed in a vacuum induction melting furnace, wherein Sm is placed at the bottom of the pot to reduce the volatilization of Sm during the melting process. The alloy is first vacuumed and then filled with inert gas. The alloy is melted and cast to obtain an alloy ingot or sheet.

[0058] Step 2: The ingot is mechanically crushed and medium-crushed under argon atmosphere, and finally jet milled to obtain fine powder with a uniform particle size of 4.35 μm;

[0059] Step 3: Add 0.3‰ of the total weight of the alloy fine powder to the lubricant zinc stearate, and mix the powder for 2 hours using a universal motion mixer to obtain a fine powder with uniform tissue distribution;

[0060] Step 4: Orient the samarium cobalt powder in an inert gas protection and magnetic field to directly obtain a samarium cobalt magnet green body; or perform cold isostatic pressing in a fluid after orientation molding to obtain a samarium cobalt magnet green body;

[0061] Step 5: Place the green billet on a 3×10 -3Heat treatment is carried out in a high vacuum environment of pa. First, the temperature is kept at 400℃ for 2 hours for primary exhaust treatment. After the primary exhaust treatment is completed, the temperature is raised to 900℃ and kept for 2 hours for secondary exhaust treatment. After the secondary exhaust treatment is completed, the temperature is raised to 1185℃ and kept for 1.5 hours for pre-sintering treatment. At this time, argon is filled as a protective gas. Then the temperature is raised to 1200℃ at a heating rate of 5℃ / min and kept for 2 hours for sintering treatment. Then, it is cooled to 1170℃ at 0.7℃ / min for 2 hours for solid solution treatment. Finally, it is quickly cooled to room temperature at 10℃ / min.

[0062] Step 6: After sintering is completed, the laminating and coating treatment is carried out. According to the size of the sintered samarium cobalt magnet, a thin-skin iron box of corresponding size is designed, with a thickness of 0.3mm. A copper foil of corresponding size is pasted on the inner wall of the thin-skin iron box, with a thickness of 75μm, and a tightly sealed iron cover is left. Then the samarium cobalt magnet is placed in the thin-skin iron box and covered with the iron cover.

[0063] Step 7: After the lamination and coating treatment is completed, aging treatment is carried out. First, the temperature is raised to 835℃ to reach the predetermined temperature and argon is filled as a protective gas. Then, the temperature is kept at this temperature for 25 hours for the first aging treatment. After completion, the temperature is lowered to 400℃ at a cooling rate of 0.7℃ / min and kept at this temperature for 15 hours for the second aging treatment. After completion, a circulating gas extraction + air cooling treatment is carried out for rapid cooling. The temperature is reduced to 250℃ at a rate of 15℃ / min. The thin iron box containing the samarium cobalt magnet is taken out and placed in coolant water at a rate of 240℃ / min for rapid cooling. Finally, a sintered samarium cobalt magnet with low temperature coefficient of residual magnetism is obtained.

[0064] The magnetic properties of the prepared sintered samarium cobalt magnets were obtained by ultra-high temperature measuring instrument: at 20℃, the remanence B r =9.53kGs, magnetic energy product (BH) max =22.3MGOe, intrinsic coercive force H cj =23.72kOe; at 300℃, remanence B r =8.87kGs, magnetic energy product (BH) max =17.56MGOe, intrinsic coercive force H cj =9.81kOe, where the remanence temperature coefficient is -0.030%.

[0065] Example 3:

[0066] Step 1: According to the nominal composition Sm 0.5 Co 4.5 Cu 0.45 Fe 1.9 Zr 0.15 Gd 0.1 Er 0.1 Dy 0.3The alloy is placed in a vacuum induction melting furnace, wherein Sm is placed at the bottom of the pot to reduce the volatilization of Sm during the melting process. The alloy is first vacuumed and then filled with inert gas. The alloy is melted and cast to obtain an alloy ingot or sheet.

[0067] Step 2: The ingot is mechanically crushed and medium-crushed in an oxygen-free environment or under atmosphere protection, and finally a jet mill is used to obtain a fine powder with a particle size of 4.30 μm;

[0068] Step 3: Add 0.35‰ of the total weight of the alloy fine powder to the lubricant zinc stearate, and mix the powder in a universal motion mixer for 3 hours to obtain a fine powder with uniform tissue distribution;

[0069] Step 4: Orient the fine powder into a shape, and then perform cold isostatic pressing to prepare a green billet;

[0070] Step 5: Place the green billet on a 3×10 -3 Heat treatment is carried out in a high vacuum environment of pa. First, the temperature is kept at 200℃ for 3 hours for primary exhaust treatment. After the primary exhaust treatment is completed, the temperature is raised to 800℃ and kept for 2 hours for secondary exhaust treatment. After the secondary exhaust treatment is completed, the temperature is raised to 1190℃ and kept for 3 hours for pre-sintering treatment. At this time, argon is filled as a protective gas. Then the temperature is raised to 1210℃ at a heating rate of 5℃ / min and kept for 1 hour for sintering treatment. Then, it is cooled to 1175℃ at 0.7℃ / min for 2 hours of solid solution treatment. Finally, it is quickly cooled to room temperature at 10℃ / min.

[0071] Step 6: After sintering is completed, the laminating and coating treatment is carried out. According to the size of the sintered samarium cobalt magnet, a thin-skin iron box of corresponding size is designed, with a thickness of 0.5mm. A copper foil of corresponding size is pasted on the inner wall of the thin-skin iron box, with a thickness of 100μm, and a tightly sealed top iron cover is left. Then the samarium cobalt magnet is placed in the thin-skin iron box and covered with the top iron cover.

[0072] Step 7: After the lamination and coating treatment is completed, aging treatment is carried out. First, the temperature is raised to 820℃ to reach the predetermined temperature and argon is filled as a protective gas. Then, the temperature is kept at this temperature for 25 hours for the first aging treatment. After completion, the temperature is lowered to 400℃ at a cooling rate of 0.7℃ / min and kept at this temperature for 10 hours for the second aging treatment. After completion, a circulating gas extraction + air cooling treatment is carried out for rapid cooling, and the temperature is reduced to 250℃ at a rate of 15℃ / min. The thin iron box containing the samarium cobalt magnet is taken out and placed in coolant water at 240℃ / min for rapid cooling. Finally, a sintered samarium cobalt magnet with low residual magnetism and temperature coefficient is obtained.

[0073] The magnetic properties of the prepared sintered samarium cobalt magnets were obtained by ultra-high temperature measuring instrument: at 20℃, the remanence B r =9.63kGs, magnetic energy product (BH) max=22.48MGOe, intrinsic coercive force H cj =15.06kOe; at 300℃, remanence B r =8.71kGs, magnetic energy product (BH) max =16.17MGOe, intrinsic coercive force H cj =8.42kOe, where the remanence temperature coefficient is -0.034%.

[0074] Example 4

[0075] The only difference from Example 1 is that in the seventh step, circulating exhaust gas + air cooling treatment is performed for rapid cooling at a cooling rate of 5°C. The remaining operations are the same as in Example 1.

[0076] Example 5

[0077] The only difference from Example 1 is that in the seventh step, a circulating exhaust gas + air cooling treatment is performed for rapid cooling at a cooling rate of 15°C. The remaining operations are the same as in Example 1.

[0078] Example 6

[0079] The only difference from Example 1 is that in the seventh step, circulating exhaust gas + air cooling treatment is performed for rapid cooling at a cooling rate of 20°C. The remaining operations are the same as in Example 1.

[0080] Example 7

[0081] The only difference from Example 1 is that in the seventh step, circulating exhaust gas + air cooling treatment is performed for rapid cooling at a cooling rate of 3°C. The remaining operations are the same as in Example 1.

[0082] Example 8

[0083] The only difference from Example 1 is that in the seventh step, a circulating exhaust gas + air cooling treatment is performed to quickly cool the temperature to 200° C. The remaining operations are the same as in Example 1.

[0084] Example 9

[0085] The only difference from Example 1 is that in the seventh step, a circulating exhaust gas + air cooling treatment is performed to quickly cool the temperature to 350° C. The remaining operations are the same as in Example 1.

[0086] Example 10

[0087] The only difference from Example 1 is that in step 7, the thin iron box containing the samarium cobalt magnet is taken out and placed in coolant water at 200°C / min for rapid cooling. The remaining operations are the same as in Example 1.

[0088] Example 11

[0089] The only difference from Example 1 is that in step 7, the thin iron box containing the samarium cobalt magnet is taken out and placed in coolant water at 300°C / min for rapid cooling. The remaining operations are the same as in Example 1.

[0090] Example 12

[0091] The only difference from Example 1 is that in step 7, the thin iron box containing the samarium cobalt magnet is taken out and placed in coolant water at 150°C / min for rapid cooling. The remaining operations are the same as in Example 1.

[0092] Example 13

[0093] The only difference from Example 1 is that in step 7, the thin iron box containing the samarium cobalt magnet is taken out and placed in coolant water at 350°C / min for rapid cooling. The remaining operations are the same as in Example 1.

[0094] Example 14

[0095] The only difference from Example 1 is that the thickness of the copper foil is 75 μm, and the rest of the operations are the same as in Example 1.

[0096] Example 15

[0097] The only difference from Example 1 is that the thickness of the copper foil is 50 μm, and the rest of the operations are the same as in Example 1.

[0098] Example 16

[0099] The only difference from Example 1 is that the thickness of the copper foil is 120 μm, and the rest of the operations are the same as in Example 1.

[0100] Example 17

[0101] The only difference from Example 1 is that the thickness of the iron sheet is 0.5 mm, and the rest of the operations are the same as in Example 1.

[0102] Example 18

[0103] The only difference from Example 1 is that the thickness of the iron sheet is 0.8 mm, and the rest of the operations are the same as in Example 1.

[0104] Example 19

[0105] The only difference from Example 1 is that the thickness of the iron sheet is 0.1 mm, and the rest of the operations are the same as in Example 1.

[0106] Example 20

[0107] The only difference from Example 1 is that in the third step, the alloy fine powder is added with 0.25‰ of the total mass of the lubricant zinc stearate, and the powder is mixed for 2 hours using a universal motion mixer to obtain a fine powder with uniform tissue distribution. The remaining operations are the same as in Example 1.

[0108] Example 21

[0109] The only difference from Example 1 is that in the third step, the alloy fine powder is added with 0.5‰ of the total mass of the lubricant zinc stearate, and the powder is mixed for 2 hours using a universal motion mixer to obtain a fine powder with uniform distribution of various tissues. The remaining operations are the same as in Example 1.

[0110] Example 22

[0111] The only difference from Example 1 is that in the fifth step, the first-level exhaust treatment is performed by keeping the temperature at 450° C. for 1 hour, and the remaining operations are the same as those in Example 1.

[0112] Example 23

[0113] The only difference from Example 1 is that in the fifth step, the first-level exhaust treatment is performed by keeping the temperature at 400° C. for 1.5 hours, and the remaining operations are the same as those in Example 1.

[0114] Example 24

[0115] The only difference from Example 1 is that in the fifth step, after the first-level exhaust treatment is completed, the temperature is raised to 850° C. and kept warm for 1.5 hours for the second-level exhaust treatment. The remaining operations are the same as in Example 1.

[0116] Example 25

[0117] The only difference from Example 1 is that in the fifth step, after the secondary exhaust treatment is completed, the temperature is raised to 1150° C. and kept at this temperature for 2 hours for pre-sintering treatment. The remaining operations are the same as in Example 1.

[0118] Example 26

[0119] The only difference from Example 1 is that in the fifth step, after the secondary exhaust treatment is completed, the temperature is raised to 1200° C. and kept at this temperature for 1 hour for pre-sintering treatment. The remaining operations are the same as in Example 1.

[0120] Example 27

[0121] The only difference from Example 1 is that in the fifth step, sintering is performed at 1190° C. and kept warm for 3 hours. The remaining operations are the same as in Example 1.

[0122] Example 28

[0123] The only difference from Example 1 is that in the fifth step, solution treatment is performed at 1150° C. for 4 hours, and the remaining operations are the same as in Example 1.

[0124] Example 29

[0125] The only difference from Example 1 is that in the fifth step, solution treatment is performed at 1200° C. for 2 h, and the remaining operations are the same as in Example 1.

[0126] Example 30

[0127] The only difference from Example 1 is that in the fifth step, after the solution treatment, the material is rapidly cooled to room temperature at a rate of 5°C / min. The remaining operations are the same as those in Example 1.

[0128] Example 31

[0129] The only difference from Example 1 is that in the fifth step, after the solution treatment, the material is rapidly cooled to room temperature at a rate of 15°C / min. The remaining operations are the same as those in Example 1.

[0130] Example 32

[0131] The only difference from Example 1 is that in the fifth step, after the solution treatment, the material is rapidly cooled to room temperature at a rate of 2°C / min. The remaining operations are the same as in Example 1.

[0132] Example 33

[0133] The only difference from Example 1 is that in the fifth step, after the solution treatment, the material is rapidly cooled to room temperature at a rate of 20°C / min. The remaining operations are the same as those in Example 1.

[0134] Comparative Example 1

[0135] The difference from Example 1 is that no lamination and coating treatment is performed.

[0136] Comparative Example 2

[0137] The difference from Example 1 is that no copper foil laminating treatment is provided inside the iron box.

[0138] Comparative Example 3

[0139] The difference from Example 1 is that the bonding and coating treatment is performed immediately after the green body is produced, but no iron cap is used for sealing.

[0140] Comparative Example 4

[0141] The difference from Example 1 is that the first step is to prepare the product according to the nominal composition Sm 1.5 Co 4.0 Cu 0.5 Fe 1.25 Zr 0.25 Gd 0.3 Dy 0.2 The materials are prepared, and then smelted and cast in an inert gas atmosphere to obtain an ingot.

[0142] Table 1

[0143]

[0144]

[0145]

[0146] During sintering and solution processing, Sm is easily volatile and reacts with impurity gases, resulting in high internal C and O contents, which in turn causes component segregation and seriously affects magnetic properties, especially high-temperature magnetic properties. By comparing the examples and comparative examples, it can be seen that low-temperature and medium-temperature insulation exhaust and inert gas protection are crucial. The sintering and aging temperatures significantly affect the microstructure of the matrix, thereby affecting the diffusion rate of the Cu element and the distribution of each phase. Controlling the grain size during the sintering and aging process is also crucial for the coercivity of the material. At the same time, the cooling rate of the samarium cobalt material after heat treatment also has a certain impact on the performance. The cooling rate that needs to be controlled during the heat treatment process mainly includes the cooling rate after solution treatment and after primary aging. If the cooling effect is not optimized, it will affect the transformation mechanism of the TbCu7-type transition 1:7 phase and the 2:17 Sm-rich and Zr-poor disordered intracellular main phase at high temperature, as well as the formation of the 1:5 Cu-rich, Fe-poor and Zr-free cell wall phase, thereby affecting the intrinsic coercivity temperature coefficient β.

[0147] The specific embodiments described in the present invention are only some of the specific implementation methods of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by persons familiar with the art within the technical scope disclosed in the present invention should be covered by the scope of protection of the present invention.

[0148] It should be noted that, according to the above-mentioned embodiments of the present invention, those skilled in the art can fully implement the contents of the entire scope of the independent claims and dependent rights of the present invention, and the implementation process and method are the same as the above-mentioned embodiments, and the parts not elaborated in detail in the present invention belong to the common known technology in the field.

Claims

1. A method for preparing a samarium cobalt permanent magnet material, characterized in that: The preparation method comprises: Step S1, according to the nominal composition Sm u Co v Cu w Fe x Zr y (Gd 0.5 Er 0.5 ) 0.5-z Dy z The ingredients are mixed to obtain a mixture; wherein, 0.5≤u≤1.5, 4.5≤v≤5.5, 0.45≤w≤0.85, 1.4≤x≤2.4, 0.14≤y≤0.24, 0.1≤Z≤0.4, and u+v+w+x+y=7.5; Step S2, melting and casting the mixture under an inert atmosphere to obtain an ingot; Step S3, crushing the ingot to obtain alloy powder; Step S4, performing orientation molding and compacting on the alloy powder to obtain a green compact; Step S5, sintering and solution treating the green body to obtain a samarium-cobalt solid solution magnet; Step S6, providing a metal coating layer on the surface of the samarium cobalt solid solution magnet and performing an aging treatment to obtain the samarium cobalt permanent magnet material; The step S6 comprises: The samarium cobalt solid solution magnet is placed in a metal box and sealed to obtain a sealed body, wherein a copper foil is provided on the inner wall of the metal box, and the samarium cobalt solid solution magnet is laminated to the copper foil in the metal box, wherein the copper foil has a thickness of 75 to 100 μm; The sealed body is placed in a furnace chamber of an aging furnace for aging treatment to obtain the samarium cobalt permanent magnet material.

2. The preparation method according to claim 1, characterized in that The aging treatment includes: Step A, heating the aging furnace to 800-900° C., filling the furnace chamber with protective gas, and maintaining the temperature at 800-900° C. for 5-30 hours to perform a first-stage aging treatment; Step B, cooling the aging furnace to 300-500°C at a cooling rate of 0.65-0.85°C / min and keeping the temperature for 5-30 hours to perform a second-stage aging treatment; Step C, cooling the aging furnace to 200-300° C. at a cooling rate of 5-15° C. / min to obtain a cooled magnet; Step D: performing a rapid cooling treatment on the cooled magnet to obtain the samarium cobalt permanent magnet material.

3. The preparation method according to claim 2, characterized in that The temperature of the first-stage aging treatment is 820-840° C. and the time is 15-20 hours; the time of the second-stage aging treatment is 5-15 hours.

4. The preparation method according to claim 2, characterized in that The metal box is made of a metal or alloy material having a melting point higher than the first-stage aging treatment temperature and having ductility, and the wall thickness of the metal box is 0.3-0.5 mm.

5. The preparation method according to claim 4, characterized in that The metal box is any one of an iron box, a tungsten box and a lead box.

6. The preparation method according to claim 2, characterized in that The step C includes subjecting the aging furnace to cyclic filling and discharging of gas and air cooling treatment so that the aging furnace is cooled to 200-300° C. at a cooling rate of 5-15° C. / min to obtain a cooled magnet.

7. The preparation method according to claim 2, characterized in that The step D includes placing the cooling magnet in a cooling liquid for the rapid cooling treatment, wherein the cooling rate of the rapid cooling treatment is 200-300° C. / min.

8. The preparation method according to any one of claims 1 to 7, characterized in that The alloy powder has a particle size of 3.5 to 4.5 μm.

9. The preparation method according to any one of claims 1 to 7, characterized in that Before the alloy powder is subjected to orientation molding, the alloy powder is mixed with a lubricant, wherein the mass of the lubricant is 0.25-0.5‰ of the mass of the alloy powder.

10. The preparation method according to any one of claims 1 to 7, characterized in that The step S5 comprises: In a vacuum environment, the green body is kept at 200-450° C. for 1-3 hours to perform a primary exhaust treatment; After completing the primary exhaust treatment, the green body is heated to 800-950° C. and kept at this temperature for 1-3 hours for secondary exhaust treatment; After completing the secondary exhaust treatment, using argon as a protective gas, the green body is heated to 1150-1200 ° C and kept warm for 1-2 hours for pre-sintering treatment, then heated to 1190-1215 ° C at a heating rate of 3-8 ° C / min and kept warm for 1-3 hours for sintering treatment, then cooled to 1150-1200 ° C for 2-4 hours for solid solution treatment, and finally air-cooled to room temperature to obtain the samarium cobalt solid solution magnet, and the air cooling rate is 5-15 ° C / min.

11. The preparation method according to claim 10, characterized in that: The temperature of the first-stage exhaust treatment is 200-400°C and the time is 1.5-2 hours; the temperature of the second-stage exhaust treatment is 850-900°C and the time is 1.5-2 hours; the temperature of the sintering treatment is 1200-1205°C and the time is 1.5-2 hours.

12. A samarium cobalt permanent magnet material obtained by the preparation method according to any one of claims 1 to 11.

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