Method for adjusting coercive force of samarium-cobalt permanent magnet material and samarium-cobalt permanent magnet material

Abstract

The invention discloses a method for adjusting the coercive force of a samarium-cobalt permanent magnet material and the samarium-cobalt permanent magnet material, and belongs to the technical field of samarium-cobalt permanent magnet materials. According to the method, two basic powder materials with high samarium content and low samarium content are prepared and mixed in proportion to obtain final powder materials, and then the final powder materials are subjected to forming, isostatic pressing, sintering, solid solution treatment and aging treatment to obtain the samarium-cobalt permanent magnet material with the intrinsic coercive force adjustable in the range of 5-35 kOe. According to the method, other elements do not need to be added, the comprehensive performance of the magnet is not affected, flexible preparation of various coercive force products can be achieved under the same heat treatment process, and the method has the advantages of being simple in process, low in cost, short in period and capable of meeting customization requirements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of samarium-cobalt permanent magnet materials, and relates to a method for adjusting the coercivity of a samarium-cobalt permanent magnet material. BACKGROUND

[0002] 2:17 type samarium-cobalt permanent magnet materials are widely used in aerospace, microwave communication, instruments, permanent magnet motors, magnetic machinery and other fields due to their high magnetic performance, high Curie temperature, low residual magnetism temperature coefficient, excellent corrosion resistance and thermal stability, and play an irreplaceable role in various industries. The current research focus of 2:17 type samarium-cobalt permanent magnet materials mainly concentrates on high performance (high magnetic energy product), high working temperature, low temperature coefficient, high mechanical performance and the like. With the rapid development of various industries and the iteration and upgrading of related products, the market demand for samarium-cobalt permanent magnet materials is increasingly diversified. In particular, in different application fields, samarium-cobalt permanent magnet materials with high, medium and low coercivity are required, and the demand side also puts forward customized demand for the coercivity index of samarium-cobalt.

[0003] Up to now, researchers mainly adjust the coercivity of samarium-cobalt permanent magnets by doping other trace elements in the samarium-cobalt permanent magnets. For example, Chinese patent CN108735415B mentions that by adding boron (B), the pinning effect of the 1:5 type cell wall phase in the samarium-cobalt permanent magnet is changed, and the intrinsic coercivity of the samarium-cobalt permanent magnet material is reduced. For different coercivity, different formulations need to be prepared, the process is relatively cumbersome, and excessive addition of boron elements will lead to a decrease in the overall performance of the samarium-cobalt permanent magnet material. For another example, Chinese patent CN102760545A mentions that by adding praseodymium (Pr) and cerium (Ce), a high remanence low coercivity samarium-cobalt permanent magnet material is prepared, and the intrinsic coercivity range is 10-20kOe. The preparation method of a samarium-cobalt magnet with an intrinsic coercivity lower than 10kOe is not mentioned, and a samarium-cobalt magnet with high coercivity (>25kOe) cannot be prepared at the same time. In addition, the powder needs to be ball milled to the nanometer level in the process, which increases the manufacturing cost and difficulty, and is not conducive to industrialization.

[0004] With the diversification, customization and precision of the coercivity index demand, it is increasingly difficult to change the coercivity of the samarium-cobalt permanent magnet material by adding elements and adjusting the production process. It is urgent to develop a method for adjusting the coercivity of the samarium-cobalt permanent magnet material, which does not need to add elements or adjust the production process, and can simply, efficiently and quickly adjust the coercivity index of the samarium-cobalt permanent magnet material to meet the market demand for different coercivity indexes and realize customized production, thereby reducing the production cost and shortening the delivery cycle. SUMMARY

[0005] The application aims to provide a method for adjusting the coercivity of Sm-Co permanent magnet material, which can simply, efficiently and quickly adjust the coercivity index of Sm-Co permanent magnet without adding elements or adjusting the production process. The inventors have found that the Sm element is a component element of the main phase and the cell wall phase in the Sm-Co magnet, and the content of the Sm element determines the size of the two-phase ratio. The change of the content of the Sm element will cause the change of the volume fraction of the cell wall phase. The cell wall phase is a domain wall pinning center, and the change of the volume fraction of the cell wall phase will have an important influence on the coercivity of the magnet. Therefore, the content of the Sm element is directly related to the magnetic properties such as the coercivity of the Sm-Co permanent magnet. Therefore, the adjustment of the coercivity of the Sm-Co permanent magnet material by changing the content of the Sm element without adding other elements will have a novel effect, and the specific technical scheme is as follows.

[0006] A method for adjusting the coercivity of Sm-Co permanent magnet material, comprising the following steps: Preparation of high-Sm-content component powder (G powder), the Sm content of which is 27-32 wt%; Preparation of low-Sm-content component powder (L powder), the Sm content of which is 21-26 wt%; According to the final coercivity requirement, the high-Sm-content component powder and the low-Sm-content component powder are mixed in proportion to obtain a final powder (M powder), and the Sm content in the final powder is 24-27 wt%; The final powder is subjected to magnetic field orientation forming, isostatic pressing, sintering, solid solution and aging treatment to obtain a Sm-Co permanent magnet material.

[0007] The method for adjusting the coercivity of Sm-Co permanent magnet material provided by the application can control the proportion of two basic powders, thereby adjusting the Sm content in the Sm-Co permanent magnet material, and realize the preparation of Sm-Co magnets with different coercivity grades under the same heat treatment process, thereby greatly improving the production flexibility and efficiency.

[0008] Further, when the intrinsic coercivity of the Sm-Co permanent magnet material is required to be 5-15 kOe, the proportion of the high-Sm-content component powder and the low-Sm-content component powder is controlled so that the Sm content in the final powder is 26-27 wt%; when the intrinsic coercivity of the Sm-Co permanent magnet material is required to be 15-28 kOe, the proportion of the high-Sm-content component powder and the low-Sm-content component powder is controlled so that the Sm content in the final powder is 25-26 wt%; and when the intrinsic coercivity of the Sm-Co permanent magnet material is required to be 28-35 kOe, the proportion of the high-Sm-content component powder and the low-Sm-content component powder is controlled so that the Sm content in the final powder is 24-25 wt%.

[0009] Further, the high-samarium-content component powder has a composition of Sm 27-32%, Co 42-52%, Cu 4-8%, Fe 10-22%, and Zr 2-4% by mass. By controlling the composition of the high-samarium-content component powder, the high-samarium-content component powder has appropriate magnetic properties and process operability.

[0010] Further, the low-samarium-content component powder has a composition of Sm 21-26%, Co 48-58%, Cu 4-8%, Fe 10-22%, and Zr 2-4% by mass. By controlling the composition of the low-samarium-content component powder, the low-samarium-content component has good magnetic property basis, which is convenient for subsequent mixing and adjustment.

[0011] Further, the high-samarium-content component powder and the low-samarium-content component powder have a surface area average particle size (SMD) of 3-6 μm. By controlling the surface area average particle size of the high-samarium-content component powder and the low-samarium-content component powder, the powder flowability, moldability, and compactness of the final magnet are ensured.

[0012] Further, the mixing process of the high-samarium-content component powder and the low-samarium-content component powder is carried out under nitrogen protection, and the oxygen content is controlled to be less than 0.5%. The powder is prevented from being oxidized, and the stability of the magnet performance is ensured.

[0013] Further, the magnetic field strength of the magnetic field orientation molding is greater than 1.5 T, and the molding density is 4.2-4.7 g / cm³, which ensures that the magnet has good orientation and preliminary molding strength.

[0014] Further, the isostatic pressing pressure is greater than 250 MPa, and the green density after isostatic pressing is 5.0-5.5 g / cm³. By controlling the isostatic pressing conditions, the green density can be improved, which provides a good basis for subsequent sintering.

[0015] Further, the sintering process includes holding at 1200-1220 °C for 1-4 hours, solid solution treatment at 1170-1190 °C for 1-10 hours, and aging treatment at 820-850 °C for 6-20 hours. By optimizing the heat treatment process, the structure of the magnet is fully formed and the performance is stable.

[0016] Further, the aging treatment further includes controlled cooling to 400 °C at a rate of 0.5-1 °C / min and holding for 1-15 hours. The microstructure of the magnet is further optimized, and the performance and thermal stability of the magnet are improved.

[0017] Further, the preparation of the high-samarium-content component powder and the preparation of the low-samarium-content component powder include the following steps: According to the composition requirements of the high-samarium-content component powder or the low-samarium-content component powder, raw materials of Sm, Co, Cu, Fe, and Zr are prepared; The raw materials are sequentially added into a crucible of an electromagnetic induction melting furnace in the order of Fe, 20-80% Co, Zr, Cu, the rest Co, and Sm, preheated by vacuum extraction to below 5 Pa, high-temperature melted after argon filling, and cast to obtain an alloy ingot; The alloy ingot is coarsely broken, medium broken, and air-mill broken to a required particle size under nitrogen protection to obtain high-samarium-content component powder or low-samarium-content component powder.

[0018] A samarium-cobalt permanent magnet material prepared by the above method has an intrinsic coercive force in the range of 5-35 kOe. The present application provides a samarium-cobalt permanent magnet material with customizable coercive force and stable performance, which meets the diversified application requirements.

[0019] In the prior art, the adjustment of the coercive force is heavily dependent on the two closely coupled variables of "changing the formula" and "adjusting the heat treatment process". The present application successfully decouples the "component design" and the "final product performance" by pre-preparing two basic powders (G powder and L powder); the complex material design problem is simplified to the proportion mixing problem of the two standard basic materials. The present application provides a "platformized" material preparation method: the G powder and the L powder constitute a material platform, and a wide range of coercive force products can be derived by simple proportion mixing, which is suitable for various market demands.

[0020] Compared with the prior art, the present application has the following beneficial technical effects: the wide range of coercive force can be adjusted by mixing only two basic powders, without adding other elements, without affecting the comprehensive performance of the magnet. The same heat treatment process can be applied to the preparation of different coercive force products, greatly simplifying the production process, reducing the cost and cycle. It is suitable for small batch, multi-variety customized production mode, and the market response speed is fast. The preparation of the basic powders (G powder and L powder) is suitable for large-scale smelting, enjoys the scale effect, and ensures the consistency of the basic materials; and the performance customization of the final product is realized by small-scale proportion mixing, which responds quickly and flexibly. The present application ingeniously solves the inherent contradiction between "scale" and "flexibility" in manufacturing: the cost advantage of large-scale production is combined with the flexibility of small batch customization, creating a new production mode, which is particularly suitable for the market demand of samarium-cobalt magnets "high performance, small batch, multi-variety", and has significant commercial application value. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be described below. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0022] A method for adjusting coercivity of Sm-Co permanent magnet material, comprising the following steps: (1) Preparation of high-samarium-content component powder A high-samarium-content component formula is prepared according to the following mass percentages: Sm: 27-32%; Co: 42-52%; Cu: 4-8%; Fe: 10-22%; and Zr: 2-4%. The prepared raw materials are sequentially placed in a crucible of an electromagnetic induction melting furnace from bottom to top in the order of Fe, 20-80% Co, Zr, Cu, remaining Co, and Sm, vacuum extraction is performed to below 5 Pa to start preheating, argon is filled after preheating is completed, high-temperature melting is performed under argon protection, and the alloy ingot with uniform composition is obtained after being cast in a copper mold.

[0023] The alloy ingot is crushed and refined in stages under nitrogen protection to obtain a powder with a surface area average particle size (SMD) of 3-6 μm, and the high-samarium-content component powder (G powder) is obtained after the powder is fully stirred by a three-dimensional mixer.

[0024] Preparation of low-samarium-content component powder A low-samarium-content component formula is prepared according to the following mass percentages: Sm: 21-26%; Co: 48-58%; Cu: 4-8%; Fe: 10-22%; and Zr: 2-4%. The prepared raw materials are sequentially placed in a crucible of an electromagnetic induction melting furnace from bottom to top in the order of Fe, part of Co, Zr, Cu, remaining Co, and Sm, vacuum extraction is performed to below 5 Pa to start preheating, argon is filled after preheating is completed, high-temperature melting is performed under argon protection, and the alloy ingot with uniform composition is obtained after being cast in a copper mold.

[0025] The alloy ingot is crushed and refined in stages under nitrogen protection to obtain a powder with a surface area average particle size (SMD) of 3-6 μm, and the low-samarium-content component powder (L powder) is obtained after the powder is fully stirred by a three-dimensional mixer.

[0026] Preparation of final powder According to the design requirements of the samarium content in the final powder, the G powder and the L powder are combined in different proportions to meet the requirements of the samarium content in the final powder. The mass percentage of samarium in the final powder is 24-27%. The combined powder is stirred by a three-dimensional mixer to obtain the final powder (M powder).

[0027] Molding and isostatic pressing The M powder is oriented and formed by a vertical pressing method, and the vacuum bag is packaged and subjected to isostatic pressing treatment to obtain a compact with certain structural strength.

[0028] Sintering, solid solution and aging Put the green body into the sintering box, stack the sintering boxes neatly on the sintering furnace tray, push the tray into the constant temperature zone of the sintering furnace, close the furnace door and vacuumize, start heating when the vacuum degree is lower than 1 Pa, after stepwise heating, fill in appropriate amount of argon, keep the temperature in the range of 1200-1220 DEG C for 1-4 h, then cool to 1170-1190 DEG C for solid solution treatment for 1-10 h, after the solid solution ends, open the fan for rapid air cooling to room temperature; then heat to 820-850 DEG C and keep for 6-20 h, control the cooling rate to 400 DEG C at the speed of 0.5-1 DEG C / min and keep for 1-15 h, after the keeping ends, air cool to room temperature to complete aging, then take out the furnace to obtain the samarium-cobalt blank.

[0029] In the industrial production process, the crucible of the electromagnetic induction melting furnace is once charged with more than 50 kg, and the order quantity of samarium-cobalt permanent magnet material products with different coercivities is often several to dozens of kilograms. The present application greatly improves the production flexibility by respectively preparing high-samarium-content component powder and low-samarium-content component powder, and then mixing the two kinds of powders in proportion according to the coercivity requirement of the product. Since only the mixing ratio of the two powders needs to be changed to obtain the required coercivity, without adding other components and without changing the production process, the production cost is greatly reduced.

[0030] The specific process of the melting in the first step and the second step is as follows: the weighed raw materials are sequentially placed in the electromagnetic induction melting furnace crucible from bottom to top in the order of Fe, 20-80% Co, Zr, Cu, the remaining Co and Sm, the furnace cover is closed, vacuumization is performed to below 5 Pa, preheating is started, the preheating time is 5-10 min, the preheating is mainly to remove the air and moisture remaining in the raw materials, the crucible and the furnace body, after the preheating ends, the vacuum system is closed, 0.04-0.08 MPa of argon is filled into the melting furnace, the filling of argon can prevent excessive volatilization of samarium during the melting process and cause the proportion of elements to be out of balance, then the power is continuously increased for heating, so that the metal raw materials in the crucible are fully melted and uniformly mixed, then the samarium-cobalt alloy ingot is cast into a water-cooled copper mold, the thickness of the alloy ingot is 15-30 mm, and the color is silver-white metal luster.

[0031] The coarse crushing and the medium crushing in the first step and the second step are mechanical crushing, the airflow mill is an ultrasonic airflow generated by a Laval nozzle, the powder is further crushed and refined after multiple impacts, and the surface area average particle size (SMD) of the powder is adjusted by adjusting the rotating speed of the sorting wheel.

[0032] The combination of the G powder and the L powder in the third step needs to be performed under nitrogen protection to prevent oxidation of the powder, and the oxygen content in the process needs to be controlled to be below 0.5%.

[0033] The magnetic field strength of the magnetic field orientation forming in the step (4) is >1.5T, the forming density is 4.2-4.7g / cm 3 ; the isostatic pressure is >250MPa, and the density of the compact after isostatic pressing is 5.0-5.5g / cm 3 .

[0034] In the step (5), the stepwise temperature rising needs to be kept at 400℃±30℃ and 800℃±30℃ for 2h±1h in stages to remove the residual gas and additives in the compact.

[0035] The pressure value of the argon gas filled in the step (5) is in the range of -0.06±0.03MPa, which mainly aims to inhibit the volatilization of samarium and avoid the imbalance of the atomic ratio in the samarium-cobalt magnet.

[0036] The "Br" in the application refers to the residual magnetism, which is the value of the magnetic flux density corresponding to the zero magnetic field strength on the saturation magnetic hysteresis loop; the "Hcb" refers to the magnetic induction coercivity, which is the value of the reverse magnetic field strength needed to reduce the magnetic induction strength to zero when the permanent magnet is reversely demagnetized; the "coercivity" refers to the intrinsic coercivity (Hcj), which is the value of the reverse magnetic field strength needed to reduce the residual magnetization of the permanent magnet to zero; the "(BH)max" refers to the maximum magnetic energy product, which is the maximum value of the product of the magnetic induction strength B and the corresponding magnetic field strength H on the demagnetization curve of the permanent magnet during demagnetization, indicating the maximum energy density that the permanent magnet can output externally; the "Hk" refers to the knee point coercivity, which is the value of the reverse magnetic field strength corresponding to 0.9Jr on the J-H demagnetization curve; and the "Hk / Hcj" refers to the squareness, which can directly represent the squareness of the J-H demagnetization curve of the permanent magnet.

[0037] Fourteen different M powder compositions are designed, and samarium-cobalt permanent magnet materials are obtained by using the same processing technology to verify the effect of adjusting the coercivity of the samarium-cobalt permanent magnet material, and the specific process is as follows.

[0038] Step 1: Preparation of high-samarium content component powder The high-samarium content component formula is configured according to the following mass percentage, wherein Sm: 27%; Co: 48%; Cu: 5.5%; Fe: 16.5%; and Zr: 3%. The prepared raw materials are sequentially placed in the crucible of the electromagnetic induction melting furnace from bottom to top in the order of Fe, part of Co, Zr, Cu, the remaining Co, and Sm, vacuumized to below 5Pa, preheated, argon gas is filled after preheating, high-temperature melting is carried out under argon protection, and the alloy ingot with uniform composition is obtained after casting in a copper mold; the alloy ingot is sequentially crushed and refined under nitrogen protection to obtain a powder with an average surface area particle size (SMD) of 4-5μm, and the high-samarium content component powder (G powder) is obtained after sufficient stirring by a three-dimensional mixer.

[0039] Step 2: Preparation of low samarium content component powder The low samarium content component formula is prepared according to the following mass percentages: Sm: 24%; Co: 51%; Cu: 5.5%; Fe: 16.5%; Zr: 3%. The prepared raw materials are placed in the crucible of an electromagnetic induction melting furnace in the order of Fe, part of Co, Zr, Cu, the remaining Co, and Sm from bottom to top. The furnace is evacuated to below 5 Pa and preheated. After preheating, argon gas is introduced and the furnace is melted at high temperature under argon protection. The resulting alloy ingot is cast into a copper mold to obtain a uniform alloy ingot. The alloy ingot is then crushed and refined step by step under nitrogen protection through coarse crushing, medium crushing, and air jet milling to obtain powder with a surface area average particle size (SMD) of 4-5 μm. After being thoroughly stirred by a three-dimensional mixer, the low samarium content component powder (L powder) is obtained.

[0040] Step 3: Preparation of the final powder Fourteen groups of final powders with different samarium contents were designed and named M1, M2, M3, M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, and M14, respectively. Their samarium mass percentages were 24.4%, 24.6%, 24.8%, 25.0%, 25.2%, 25.4%, 25.6%, 25.8%, 26.0%, 26.2%, 26.4%, 26.6%, 26.8%, and 27.0%, respectively. Based on these 14 samarium content designs, G powder and L powder were combined, and the combined powders were subjected to three-dimensional mixing to obtain the 14 final powder groups (M1 to M14).

[0041] Step 4: Molding and Isostatic Pressing The 14 final powder materials were magnetically oriented using a vertical pressing method with a magnetic field strength of 1.8T and a forming density of 4.5 g / cm³. 3 After being vacuum-packed, it underwent isostatic pressing at a pressure of 270 MPa, resulting in a density of 5.2 g / cm³. 3 Fourteen sets of pressed blanks were obtained respectively.

[0042] Step 5: Sintering, Solution Treatment and Aging Fourteen sets of pressed billets were placed in sintering boxes, which were then neatly stacked on a sintering furnace tray. The tray was pushed into the constant temperature zone of the sintering furnace, the furnace door was closed, and a vacuum was drawn. Heating began when the vacuum level was below 1 Pa. The temperature was gradually increased to 1208℃, and argon gas at -0.06±0.01 MPa was introduced and held at 1208℃ for 2 hours. The temperature was then cooled to 1185℃ for solution treatment for 6 hours. After solution treatment, the fan was turned on for rapid air cooling to room temperature. The temperature was then increased to 840℃ and held for 8 hours. The temperature was then controlled to cool to 400℃ at a rate of 0.8℃ / min and held for 2 hours. After holding, the temperature was air cooled to room temperature to complete aging. The billets were then removed from the furnace to obtain 14 sets of samarium cobalt billets.

[0043] The magnetic properties of the 14 samarium cobalt blanks were tested and are shown in Table 1.

[0044] Table 1. Magnetic properties of 14 groups of samarium cobalt blanks

[0045] As can be seen from Table 1, by controlling the ratio of the two basic powders and adjusting the samarium content in the samarium-cobalt permanent magnet material, samarium-cobalt permanent magnet materials with different coercivity can be obtained without adding other components or adjusting the production process.

[0046] Comparative Example To obtain samarium cobalt magnets with Hcj equivalent to those in M1, M3, M5, M7 and M9 in the above embodiments, five different samarium content formulations were prepared using a traditional single-component method. The samarium contents (wt%) were 24.4%, 24.8%, 25.2%, 25.6% and 26.0%, respectively, and were named C1, C2, C3, C4 and C5. The formulation components are shown in Table 2.

[0047] Table 2. Five samarium-cobalt magnet formulations prepared using traditional single-component methods.

[0048] C1 to C5 were smelted separately with a minimum smelting weight of 50 kg. The prepared raw materials were placed in the crucible of an electromagnetic induction melting furnace in the order of Fe, part of Co, Zr, Cu, the remaining Co, and Sm from bottom to top. The furnace was evacuated to below 5 Pa for preheating. After preheating, argon gas was introduced, and high-temperature melting was carried out under argon protection. The resulting alloy ingots were cast into copper molds to obtain uniform alloy ingots. This process was repeated 5 times to obtain alloy ingots of formulations C1 to C5. The alloy ingots were then subjected to coarse crushing, medium crushing, and air jet milling under nitrogen protection to obtain powder with a surface area average particle size (SMD) of 4-5 μm. After thorough mixing in a three-dimensional mixer, traditional single-component powder was obtained. This process was repeated 5 times to obtain traditional single-component powders of formulations C1 to C5.

[0049] Five traditional single-component powders were magnetically oriented using a vertical pressing method with a magnetic field strength of 1.8T, resulting in a molding density of 4.5 g / cm³. 3 After being vacuum-packed, it underwent isostatic pressing at a pressure of 270 MPa, resulting in a density of 5.2 g / cm³. 3 Five sets of pressed blanks were obtained respectively.

[0050] Five sets of pressed billets were placed in sintering boxes, which were then neatly stacked on a sintering furnace tray. The tray was pushed into the constant temperature zone of the sintering furnace, the furnace door was closed, and a vacuum was drawn. Heating began when the vacuum level was below 1 Pa. The temperature was gradually increased to 1208℃, and argon gas at -0.06±0.01 MPa was introduced. The temperature was held at 1208℃ for 2 hours, followed by cooling to 1185℃ for solution treatment for 6 hours. After solution treatment, a fan was turned on for rapid air cooling to room temperature. The temperature was then increased to 840℃ and held for 8 hours, followed by controlled cooling at a rate of 0.8℃ / min to 400℃ and held for 2 hours. After holding, the temperature was air-cooled to room temperature to complete aging. The resulting five sets of samarium cobalt billets were then removed from the furnace. The magnetic properties of the five sets of samarium cobalt billets are shown in Table 3.

[0051] Table 3. Magnetic properties of five samarium-cobalt magnet blanks prepared using the traditional single-component method.

[0052] As shown in Table 3, samarium cobalt magnets with Hcj equivalent to those in M1, M3, M5, M7, and M9 in the examples can also be produced using the traditional single-component powder method. However, since the minimum input for a single smelting in industrial production is 50 kg, the traditional single-component powder method in the comparative example requires repeated smelting of alloy ingots with formulations C1 to C5, with each ingot weighing at least 50 kg. To obtain five different Hcj values, a minimum of 250 kg of alloy ingots needs to be input and smelted five times, which is cumbersome and costly. Due to the small and scattered order structure in the samarium cobalt market, orders weighing only a few kilograms are common. Using the traditional single-component powder method often results in more than 80% of the alloy ingots becoming obsolete inventory, leading to increased production costs.

[0053] Although embodiments of the present invention have been shown and described above, it is understood that these embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and alterations to the above embodiments within the scope of the present invention without departing from its principles and spirit. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A method for adjusting the coercivity of samarium cobalt permanent magnet materials, characterized in that, Includes the following steps: A high samarium content component powder was prepared, with a samarium content of 27-32 wt%. A low samarium content component powder was prepared, with a samarium content of 21-26 wt%. Based on the final coercivity requirement, the high samarium content component powder and the low samarium content component powder are mixed in a certain proportion to obtain the final powder, wherein the samarium content in the final powder is 24~27 wt%; The final powder was subjected to magnetic field orientation molding, isostatic pressing, sintering, solution treatment and aging to obtain samarium cobalt permanent magnet material.

2. The method as described in claim 1, characterized in that, When the intrinsic coercivity of the required samarium-cobalt permanent magnet material is 5-15 kOe, the ratio of high-samarium content component powder to low-samarium content component powder is controlled to achieve a samarium content of 26-27 wt% in the final powder. When the intrinsic coercivity of the required samarium-cobalt permanent magnet material is 15-28 kOe, the ratio of high-samarium content component powder to low-samarium content component powder is controlled to achieve a samarium content of 25-26 wt% in the final powder. When the intrinsic coercivity of the required samarium-cobalt permanent magnet material is 28-35 kOe, the ratio of high-samarium content component powder to low-samarium content component powder is controlled to achieve a samarium content of 24-25 wt% in the final powder.

3. The method as described in claim 1 or 2, characterized in that, The composition of the high samarium content component powder by mass percentage is: Sm 27~32%, Co 42~52%, Cu 4~8%, Fe 10~22%, Zr 2~4%.

4. The method as described in claim 1 or 2, characterized in that, The composition of the low samarium content component powder by mass percentage is: Sm 21~26%, Co 48~58%, Cu 4~8%, Fe 10~22%, Zr 2~4%.

5. The method as described in claim 1 or 2, characterized in that, The average surface area particle size of both the high samarium content component powder and the low samarium content component powder is 3~6 μm.

6. The method as described in claim 1 or 2, characterized in that, The mixing process of the high samarium content component powder and the low samarium content component powder is carried out under nitrogen protection, and the oxygen content is controlled below 0.5%.

7. The method as described in claim 1 or 2, characterized in that, The magnetic field strength for the magnetic field orientation molding is greater than 1.5T, and the molding density is 4.2~4.7 g / cm³.

8. The method as described in claim 1 or 2, characterized in that, The isostatic pressing pressure is greater than 250 MPa, and the density of the compact after isostatic pressing is 5.0~5.5 g / cm³.

9. The method as described in claim 1 or 2, characterized in that, The sintering process includes holding at 1200~1220℃ for 1~4 hours, solution treatment at 1170~1190℃ for 1~10 hours, and aging treatment at 820~850℃ for 6~20 hours.

10. The method as described in claim 1 or 2, characterized in that, The aging process also includes cooling to 400°C at a controlled rate of 0.5~1°C / min and holding at that temperature for 1~15 hours.

11. The method as described in claim 1 or 2, characterized in that, The preparation of high samarium content component powder and low samarium content component powder includes the following steps: Prepare raw materials according to the composition requirements of high samarium content powder or low samarium content powder: Sm, Co, Cu, Fe and Zr; The raw materials are added to the crucible of the electromagnetic induction melting furnace in the order of Fe, 20-80% Co, Zr, Cu, remaining Co, and Sm. The furnace is preheated by evacuating to below 5 Pa, then purged with argon and melted at high temperature to obtain an alloy ingot. The alloy ingots are crushed to the required particle size under nitrogen protection through coarse crushing, medium crushing, and air jet milling to obtain high samarium content component powder or low samarium content component powder.

12. A samarium-cobalt permanent magnet material, characterized in that, Prepared by the method described in any one of claims 1 to 11, its intrinsic coercivity is adjustable in the range of 5 to 35 kOe.

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