Method for regulating distribution of zirconium element in samarium-cobalt magnet

Abstract

The invention discloses a method for regulating and controlling zirconium element distribution in a samarium-cobalt magnet. The method comprises the following steps: (1) smelting raw materials including Sm, Co, Fe, Cu and Zr to obtain a samarium cobalt cast ingot; (2) the samarium cobalt cast ingot is subjected to intermediate crushing treatment, and alloy coarse powder is obtained; performing jet milling on the alloy coarse powder to obtain alloy fine powder; (3) molding the alloy fine powder to obtain a samarium-cobalt magnet blank; (4) pre-sintering the samarium cobalt magnet blank at 1170-1190 DEG C for 5-18 minutes to obtain a pre-sintered body; the pre-sintered body is sintered for 110 min to 125 min at the temperature ranging from 1200 DEG C to 1220 DEG C under the condition that the vacuum degree ranges from 0.045 MPa to 0.06 MPa, then solid solution is conducted for 170 min to 190 min at the temperature ranging from 1160 DEG C to 1175 DEG C, and a solid solution is obtained; and (5) carrying out aging treatment on the solid solution. According to the method, the zirconium element can be distributed in the samarium-cobalt magnet in a thin strip shape, and the dispersion degree is high.

Description

Technical Field

[0001] The invention relates to a method for regulating the distribution of zirconium elements in a samarium-cobalt magnet. Background Art

[0002] Samarium cobalt magnets are widely used in aerospace and high-end electronic equipment due to their stable high-temperature performance and excellent corrosion resistance. Coercivity is a key indicator of a samarium cobalt magnet's resistance to demagnetization and plays a key role in its ability to maintain its magnetic properties and stability in complex environments.

[0003] CN112435846A discloses a method for preparing a samarium-cobalt permanent magnet material. The method comprises the following steps: preparing 26.5% samarium, 50.8% cobalt, 9.5% copper, 10% iron, and 3.2% zirconium by weight, and heating the mixture in a crucible in an induction furnace; casting the alloy liquid into a water-cooled copper mold and rapidly cooling the mixture; and subjecting the alloy ingot to coarse and medium crushing; adding a lubricant and an antioxidant to the medium-crushed alloy powder, and then jet milling the mixture to obtain alloy powder; orienting the alloy powder in a mold to obtain a green compact; maintaining the green compact at 1200-1230°C for 150 minutes, at 1185-1215°C for 4 hours, and finally at 1170-1200°C for 2 hours; and after cooling, maintaining the mixture at 800-820°C for 12 hours, then reducing the temperature to 600°C for 12 hours, and then reducing the temperature to 400°C to obtain the samarium-cobalt permanent magnet material.

[0004] CN106057390A discloses a preparation method for improving the comprehensive magnetic properties of sintered samarium-cobalt permanent magnets, comprising the steps of melting and refining raw materials having a samarium content of 24.5-26%, a cobalt content of 52-56%, an iron content of 7.5-12%, a copper content of 6.5-8% and a zirconium content of 2-4%, and then pouring the raw materials into a condensing mold and rapidly cooling the smeared samarium-cobalt alloy ingot; coarsely crushing the samarium-cobalt alloy ingot into coarse particles; and further grinding a portion of the coarse particles by using a ball mill. The method comprises the following steps: crushing the coarse particles to obtain ball-milled powder; further crushing another portion of the coarse particles by using a jet mill to obtain jet-milled powder; uniformly mixing the jet-milled powder and the ball-milled powder to obtain a mixed magnetic powder; orienting the mixed magnetic powder in a magnetic field and pressing it into a shape, and then performing cold isostatic pressing to obtain a samarium-cobalt blank; vacuum pre-sintering the samarium-cobalt blank, then sintering it in an inert gas atmosphere, then cooling it for solid solution, and air-cooling it to room temperature to obtain a sintered blank; and performing an aging treatment on the sintered blank to obtain a samarium-cobalt permanent magnet.

[0005] CN103325513A discloses a method for preparing a permanent magnetic material. The method comprises the following steps: melting and refining raw materials, pouring the raw materials into a water-cooled copper mold and rapidly cooling the raw materials to obtain a samarium-cobalt alloy ingot; crushing the samarium-cobalt alloy ingot into coarse particles, and pulverizing the coarse particles into magnetic powder; orienting the magnetic powder into a molded product, and then cold isostatically pressing the magnetic powder to obtain a samarium-cobalt molded product; pre-sintering the samarium-cobalt molded product in a tube furnace at 1000-1190° C. for 30 minutes in a vacuum, then sintering the product at 1200-1220° C. with argon for 90-120 minutes, then cooling the product to 1160-1180° C. for solution treatment for 90-120 minutes, and finally air-cooling the product to 25-30° C. to obtain a sintered product; and keeping the sintered product at 800-830° C. for 10-20 hours, then cooling the product to 400° C. for 10-15 hours, and finally cooling the product to 25-30° C. to obtain a permanent magnetic material. The permanent magnet material consists of the following components in percentage by mass: 24.5-26% of samarium, 52-56% of cobalt, 7.5-12% of iron, 6.5-8% of copper and 2-4% of zirconium.

[0006] The distribution of Zr in the samarium cobalt permanent magnet material obtained by the above method is uneven, and the coercive force of the permanent magnet material is low. Summary of the Invention

[0007] In light of this, the present invention aims to provide a method for regulating the distribution of zirconium in samarium-cobalt magnets. This method enables the zirconium to be distributed in the samarium-cobalt magnet in a thin, highly dispersed manner. Furthermore, the samarium-cobalt magnets obtained by this method exhibit a high coercive force.

[0008] The present invention achieves the above-mentioned purpose through the following technical solutions.

[0009] The present invention provides a method for regulating the distribution of zirconium elements in samarium-cobalt magnets, comprising the following steps:

[0010] (1) smelting raw materials including Sm, Co, Fe, Cu and Zr to obtain a samarium-cobalt ingot;

[0011] In the raw materials, the content of Sm is 24.6-25.2 wt%, the content of Co is 57.5-59.0 wt%, the content of Fe is 7.0-7.8 wt%, the content of Cu is 5.8-6.9 wt%, and the content of Zr is 2.7-3.5 wt%;

[0012] (2) crushing the samarium-cobalt ingot to obtain alloy coarse powder; jet milling the alloy coarse powder to obtain alloy fine powder;

[0013] (3) orienting and pressing the alloy fine powder into a shape, and then performing cold isostatic pressing to obtain a samarium-cobalt magnet blank;

[0014] (4) pre-sintering the samarium cobalt magnet blank at 1170-1190° C. for 5-18 minutes under vacuum conditions to obtain a pre-sintered body; sintering the pre-sintered body at 1200-1220° C. for 110-125 minutes in an inert gas atmosphere at a vacuum degree of 0.045-0.06 MPa, and then solutionizing at 1160-1175° C. for 170-190 minutes to obtain a solid solution;

[0015] (5) The solid solution is subjected to aging treatment to obtain a samarium cobalt magnet.

[0016] According to the method of the present invention, preferably, the aging treatment includes primary aging treatment and secondary aging treatment;

[0017] The primary aging treatment temperature is 815-835°C, and the primary aging treatment time is 670-730 minutes; the secondary aging treatment temperature is 401-410°C, and the secondary aging treatment time is 310-350 minutes.

[0018] According to the method of the present invention, preferably, in the raw material, the Sm content is 24.8-25.1wt%, the Co content is 57.6-57.9wt%, the Fe content is 7.4-7.6wt%, the Cu content is 6.6-6.8wt%, and the Zr content is 2.8-3wt%.

[0019] According to the method of the present invention, preferably, in the raw material, the Sm content is 24.8-25.1wt%, the Co content is 58.4-58.8wt%, the Fe content is 7.1-7.3wt%, the Cu content is 6.0-6.4wt%, and the Zr content is 3.1-3.3wt%.

[0020] According to the method of the present invention, preferably, the pre-sintering temperature is 1175-1180° C., and the pre-sintering time is 8-16 min; the sintering temperature is 1205-1215° C., and the sintering time is 110-120 min; the solution temperature is 1165-1170° C., and the solution time is 175-185 min.

[0021] According to the method of the present invention, preferably, the primary aging treatment temperature is 820-830° C., and the primary aging treatment time is 680-710 min; the secondary aging treatment temperature is 402-405° C., and the secondary aging treatment time is 320-330 min.

[0022] According to the method of the present invention, preferably, the particle size D of the alloy coarse powder is 50 The particle size of the alloy fine powder is 6.5~7.3μm, and the particle size D 50 3.5~4.5μm.

[0023] According to the method of the present invention, preferably, the orientation is carried out under the condition of a magnetic field strength of 1.5 to 3 T and a cold isostatic pressing pressure of 250 to 330 MPa.

[0024] According to the method of the present invention, preferably, the zirconium element is uniformly dispersed in the samarium cobalt magnet in the form of strips.

[0025] According to the method of the present invention, preferably, the coercive force of the samarium cobalt magnet is ≥40 kOe.

[0026] The method of the present invention enables the zirconium element to be distributed in a samarium-cobalt magnet in the form of thin strips with a high degree of dispersion. The present invention has discovered that the distribution morphology of the zirconium element in the samarium-cobalt magnet has a significant impact on the coercive force of the samarium-cobalt magnet. The distribution morphology of the zirconium element in the samarium-cobalt magnet of the present invention helps to improve the coercive force of the samarium-cobalt magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a transmission electron microscope image of the samarium cobalt magnet of Example 1.

[0028] Figure 2 This is a transmission electron microscope image of the samarium cobalt magnet of Example 2.

[0029] Figure 3 This is a transmission electron microscope image of the samarium cobalt magnet of Comparative Example 1.

[0030] Figure 4 This is a transmission electron microscope image of the samarium cobalt magnet of Comparative Example 2. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0032] The method for regulating the distribution of zirconium elements in samarium-cobalt magnets of the present invention comprises the following steps:

[0033] The following describes each step in detail: (1) preparing a samarium-cobalt ingot; (2) crushing; (3) forming; (4) sintering and solutionizing; and (5) aging.

[0034] Steps for preparing samarium cobalt ingots

[0035] The present invention melts raw materials comprising Sm, Co, Fe, Cu, and Zr to produce a samarium-cobalt ingot. The raw materials of the present invention do not contain heavy rare earth elements. Preferably, the raw materials of the present invention consist of Sm, Co, Fe, Cu, and Zr.

[0036] In the raw material, the content of Sm is 24.6-25.2 wt %; preferably 24.8-25.1 wt %; more preferably 24.9-25 wt %.

[0037] In the raw material, the content of Co is 57.5-59.0 wt %. In certain embodiments, the content of Co is 57.6-57.9 wt %. In other embodiments, the content of Co is 58.4-58.8 wt %.

[0038] In the raw material, the content of Fe is 7.0-7.8 wt %. In certain embodiments, the content of Fe is 7.4-7.6 wt %. In other embodiments, the content of Fe is 7.1-7.3 wt %.

[0039] In the raw material, the content of Cu is 5.8-6.9 wt %. In certain embodiments, the content of Cu is 6.6-6.8 wt %. In other embodiments, the content of Cu is 6.0-6.4 wt %.

[0040] In the raw material, the content of Zr is 2.7-3.5 wt %. In some embodiments, the content of Zr is 2.8-3 wt %. In other embodiments, the content of Zr is 3.1-3.3 wt %.

[0041] According to one embodiment of the present invention, the raw material consists of 25 wt % Sm, 57.7 wt % Co, 7.5 wt % Fe, 6.8 wt % Cu and 3 wt % Zr.

[0042] According to another embodiment of the present invention, the raw material consists of 24.9 wt % Sm, 58.6 wt % Co, 7.2 wt % Fe, 6.1 wt % Cu and 3.2 wt % Zr.

[0043] The combination of the raw material composition and the process helps to make the zirconium element in the samarium cobalt magnet appear in thin strips and be evenly dispersed, thereby improving the coercive force of the samarium cobalt magnet.

[0044] Crushing steps

[0045] The invention performs medium crushing on the samarium-cobalt ingot to obtain alloy coarse powder; and air flow mills the alloy coarse powder to obtain alloy fine powder.

[0046] Particle size D of alloy coarse powder 50 It may be 6.5 to 7.3 μm, preferably 6.7 to 7.1 μm, and more preferably 6.9 to 7 μm.

[0047] Particle size of alloy fine powder D 50 It may be 3.5 to 4.5 μm, preferably 3.8 to 4.3 μm, and more preferably 4.1 to 4.2 μm.

[0048] Molding steps

[0049] The invention orients and presses alloy fine powder into shape, and then performs cold isostatic pressing to obtain a samarium-cobalt magnet blank.

[0050] The orientation is carried out under the condition of a magnetic field strength of 1.5 to 3T; preferably, under the condition of a magnetic field strength of 2 to 2.5T.

[0051] The cold isostatic pressing pressure may be 250 to 330 MPa, preferably 280 to 320 MPa, and more preferably 280 to 290 MPa.

[0052] Sintering and solutionizing steps

[0053] The invention pre-sinters a samarium cobalt magnet blank to obtain a pre-sintered body; sinters the pre-sintered body and then performs solid solution to obtain a solid solution.

[0054] Pre-sintering is carried out under vacuum conditions. Vacuum means pressure < 2×10 -3 Pa.

[0055] The pre-sintering temperature is 1170-1190° C., preferably 1175-1180° C., more preferably 1175-1177° C. The pre-sintering time is 5-18 minutes, preferably 8-16 minutes, and preferably 15-16 minutes.

[0056] The sintering is carried out in an inert gas atmosphere, preferably argon.

[0057] The sintering is carried out under a vacuum degree of 0.045 to 0.06 MPa. Preferably, the sintering is carried out under a vacuum degree of 0.05 to 0.06 MPa.

[0058] The sintering temperature is 1200-1220° C., preferably 1205-1210° C., and more preferably 1205-1207° C. The sintering time is 110-125 min, preferably 110-115 min, and more preferably 113-115 min.

[0059] The solid solution is carried out under an inert gas atmosphere. Preferably, the inert gas is argon.

[0060] The solid solution is carried out under the condition of a vacuum degree of 0.045 to 0.06 MPa. Preferably, the solid solution is carried out under the condition of a vacuum degree of 0.05 to 0.06 MPa.

[0061] The solution temperature is 1160-1175° C., preferably 1165-1170° C., and more preferably 1168-1170° C. The solution time is 170-190 min, preferably 180-185 min.

[0062] After the solutionizing step, the step of air-cooling the solution product for 10 to 30 minutes and then cooling it to 20 to 35° C. in the furnace may be further included.

[0063] According to one embodiment of the present invention, pre-sintering is carried out under vacuum conditions, the pre-sintering temperature is 1180°C, and the pre-sintering time is 10 minutes; sintering is carried out in an argon atmosphere with a vacuum degree of 0.05 MPa, the sintering temperature is 1210°C, and the sintering time is 110 minutes; and solid solution is carried out in an argon atmosphere with a vacuum degree of 0.05 MPa, the solid solution temperature is 1165°C, and the solid solution time is 175 minutes.

[0064] According to another embodiment of the present invention, pre-sintering is carried out under vacuum conditions, the pre-sintering temperature is 1175°C, and the pre-sintering time is 15 minutes; sintering is carried out in an argon atmosphere and a vacuum degree of 0.06 MPa, the sintering temperature is 1205°C, and the sintering time is 115 minutes; solid solution is carried out in an argon atmosphere and a vacuum degree of 0.06 MPa, the solid solution temperature is 1170°C, and the solid solution time is 185 minutes.

[0065] The above sintering and solution treatment conditions, in combination with the composition of the elements in the raw materials, help to make the zirconium element in the samarium cobalt magnet appear in thin strips and be evenly dispersed, thereby improving the coercive force of the samarium cobalt magnet.

[0066] Steps of aging treatment

[0067] The invention performs aging treatment on the solid solution to obtain the samarium cobalt magnet.

[0068] The aging treatment can be performed under an inert gas atmosphere, preferably argon.

[0069] The aging treatment may be performed under a vacuum degree of 0.02 to 0.08 MPa. Preferably, the aging treatment is performed under a vacuum degree of 0.04 to 0.06 MPa.

[0070] Aging treatment includes primary aging treatment and secondary aging treatment. Primary aging treatment and secondary aging treatment are carried out in sequence.

[0071] The primary aging treatment temperature is 815-835°C, preferably 820-830°C, and more preferably 820-825°C.

[0072] The primary aging treatment time is 670 to 730 minutes, preferably 680 to 710 minutes, and more preferably 680 to 690 minutes.

[0073] The secondary aging treatment temperature is 401-410°C, preferably 402-405°C, and more preferably 402-403°C.

[0074] The secondary aging treatment time is 310 to 350 minutes, preferably 320 to 330 minutes, and more preferably 320 to 325 minutes.

[0075] In certain embodiments, the primary aging treatment temperature is 830° C., and the primary aging treatment time is 700 min; the secondary aging treatment temperature is 405° C., and the secondary aging treatment time is 330 min.

[0076] In certain embodiments, the primary aging treatment temperature is 820° C., and the primary aging treatment time is 680 min; the secondary aging treatment temperature is 402° C., and the secondary aging treatment time is 320 min.

[0077] After the aging treatment, the method may further include the step of cooling the aging-treated product to 20-35° C. in the furnace.

[0078] The above aging treatment conditions, in combination with the composition of the elements in the raw materials, help to make the zirconium element in the samarium cobalt magnet appear in thin strips and be evenly dispersed, thereby improving the coercive force of the samarium cobalt magnet.

[0079] The coercive force of the samarium cobalt magnet is ≥40 kOe, preferably ≥42 kOe, and more preferably ≥44 kOe. The above coercive force is the coercive force of the samarium cobalt magnet at 25°C.

[0080] In samarium cobalt magnets, zirconium elements are dispersed in the form of strips.

[0081] Here is the test method:

[0082] Transmission electron microscope image: After preheating the microscope, place the copper mesh in the sample holder and insert it into the sample chamber inside the microscope barrel via the airlock, ensuring that the sample holder is securely fixed. Adjust the objective aperture and stigmator to ensure that the electron beam is well focused and the optical axis is coaxial with the lens system to avoid image distortion. Select an appropriate magnification under brightfield conditions, observe the image on the screen, and adjust the brightness and contrast to optimal levels before capturing the image with a camera.

[0083] Coercivity: Place the sample in the center of the magnetic field chamber, aligning the magnetization direction with the magnetic field (axially magnetized samples should be placed perpendicular to the pulsed magnetic field). Secure the sample with a non-magnetic fixture to avoid introducing additional magnetic fields. Ensure the magnetic sensor is close to the sample surface to accurately capture the local magnetic field signal. The instrument then automatically measures the coercivity.

[0084] Examples 1-2 and Comparative Examples 1-2

[0085] Raw materials consisting of Sm, Co, Fe, Cu and Zr are smelted to obtain samarium-cobalt ingots.

[0086] The samarium-cobalt ingot is subjected to medium crushing to obtain alloy coarse powder; and the alloy coarse powder is jet-milled to obtain alloy fine powder.

[0087] The alloy fine powder is oriented and pressed into shape in a magnetic field with an intensity of H, and then cold isostatically pressed to obtain a samarium-cobalt magnet blank.

[0088] In a tube furnace, under vacuum conditions (pressure < 2×10 -3 Pa), pre-sintering the samarium-cobalt magnet blank to obtain a pre-sintered body. Argon gas was introduced into a tube furnace until the vacuum level inside the tube furnace reached P, and the pre-sintered body was sintered to obtain a sintered body. The sintered body was solutionized, air-cooled for 20 minutes, and then cooled in the furnace to 25°C to obtain a solid solution.

[0089] The solid solution is placed in a vacuum furnace, the furnace door is closed and vacuum is evacuated, then heating is turned on and argon is filled until the vacuum degree in the vacuum furnace reaches 0.05 MPa, the solid solution is subjected to primary aging treatment and secondary aging treatment in sequence, and then cooled to 25°C in the furnace to obtain a samarium cobalt magnet.

[0090] The composition of the raw materials, the parameters of each step and the coercive force of the samarium cobalt magnet are shown in Table 1.

[0091] Table 1

[0092]

[0093] Figure 1 This is a transmission electron microscope image of the samarium cobalt magnet of Example 1. Figure 1 It can be seen that in the samarium-cobalt magnet of Example 1, the zirconium element is in the form of thin strips and has a high degree of dispersion.

[0094] Figure 2 This is a transmission electron microscope image of the samarium cobalt magnet of Example 2. Figure 2 It can be seen that in the samarium-cobalt magnet of Example 2, the zirconium element is in the form of thin strips and has a high degree of dispersion.

[0095] Figure 3 This is a transmission electron microscope image of the samarium cobalt magnet of Comparative Example 1. Figure 3 It can be seen that in the samarium-cobalt magnet of Comparative Example 1, the zirconium element forms relatively thick stripes and has a low degree of dispersion.

[0096] Figure 4 This is a transmission electron microscope image of the samarium cobalt magnet of Comparative Example 2. Figure 4 It can be seen that in the samarium-cobalt magnet of Comparative Example 2, the stripe-like morphology formed by the zirconium element cannot be clearly observed, and the distribution is uneven.

[0097] The present invention is not limited to the above-mentioned embodiments. Any modification, improvement, or substitution that can be conceived by those skilled in the art without departing from the essential content of the present invention shall fall within the scope of the present invention.

Claims

1. A method for regulating the distribution of zirconium elements in samarium cobalt magnets, characterized in that: The steps include: (1) smelting raw materials including Sm, Co, Fe, Cu and Zr to obtain a samarium-cobalt ingot; In the raw materials, the content of Sm is 24.6-25.2 wt%, the content of Co is 57.5-59.0 wt%, the content of Fe is 7.0-7.8 wt%, the content of Cu is 5.8-6.9 wt%, and the content of Zr is 2.7-3.5 wt%; (2) crushing the samarium-cobalt ingot to obtain alloy coarse powder; jet milling the alloy coarse powder to obtain alloy fine powder; (3) orienting and pressing the alloy fine powder into a shape, and then performing cold isostatic pressing to obtain a samarium-cobalt magnet blank; (4) pre-sintering the samarium cobalt magnet blank at 1170-1190° C. for 5-18 minutes under vacuum conditions to obtain a pre-sintered body; sintering the pre-sintered body at 1200-1220° C. for 110-125 minutes in an inert gas atmosphere at a vacuum degree of 0.045-0.06 MPa, and then solutionizing at 1160-1175° C. for 170-190 minutes to obtain a solid solution; (5) The solid solution is subjected to aging treatment to obtain a samarium cobalt magnet.

2. The method according to claim 1, characterized in that Aging treatment includes primary aging treatment and secondary aging treatment; The primary aging treatment temperature is 815-835°C, and the primary aging treatment time is 670-730 minutes; the secondary aging treatment temperature is 401-410°C, and the secondary aging treatment time is 310-350 minutes.

3. The method according to claim 1, characterized in that In the raw materials, the content of Sm is 24.8-25.1 wt%, the content of Co is 57.6-57.9 wt%, the content of Fe is 7.4-7.6 wt%, the content of Cu is 6.6-6.8 wt%, and the content of Zr is 2.8-3 wt%.

4. The method according to claim 1, wherein In the raw materials, the content of Sm is 24.8-25.1 wt%, the content of Co is 58.4-58.8 wt%, the content of Fe is 7.1-7.3 wt%, the content of Cu is 6.0-6.4 wt%, and the content of Zr is 3.1-3.3 wt%.

5. The method according to claim 1, characterized in that The pre-sintering temperature is 1175-1180° C., and the pre-sintering time is 8-16 minutes; the sintering temperature is 1205-1215° C., and the sintering time is 110-120 minutes; the solid solution temperature is 1165-1170° C., and the solid solution time is 175-185 minutes.

6. The method according to claim 2, characterized in that The primary aging treatment temperature is 820-830°C, and the primary aging treatment time is 680-710 minutes; the secondary aging treatment temperature is 402-405°C, and the secondary aging treatment time is 320-330 minutes.

7. The method according to claim 1, characterized in that Particle size D of alloy coarse powder 50 The particle size of the alloy fine powder is 6.5~7.3μm, and the particle size D 50 3.5~4.5μm.

8. The method according to claim 1, characterized in that The orientation is carried out under the condition of a magnetic field strength of 1.5 to 3 T and a cold isostatic pressing pressure of 250 to 330 MPa.

9. The method according to claim 1, characterized in that The zirconium element is uniformly dispersed in the samarium cobalt magnet in the form of strips.

10. The method according to claim 1, characterized in that The coercive force of the samarium cobalt magnet is ≥40 kOe.

Images