High temperature stability rare earth cobalt permanent magnet material and preparation method

Abstract

The application relates to a high-temperature-stability rare earth cobalt permanent magnet material and a preparation method, and belongs to the technical field of rare earth permanent magnet materials. The application solves the problems of poor temperature stability, large temperature coefficient and large magnetic flux change in the prior art. The high-temperature-stability rare earth cobalt permanent magnet material is prepared by compounding A alloy and B alloy according to mass proportions, wherein the mass proportion of the A alloy is 50% to 80%; the A alloy comprises 2 to 4 rare earth elements, wherein the content proportion of Gd element in the rare earth elements is not less than 50%; and the B alloy comprises 2 to 4 rare earth elements, wherein the content of Sm element in the rare earth elements is not less than 80%. The preparation of the high-temperature-stability rare earth cobalt permanent magnet material is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rare earth permanent magnet materials, and particularly relates to a high-temperature-stability rare earth cobalt permanent magnet material and a preparation method. BACKGROUND

[0002] Rare earth permanent magnet materials have excellent magnetic properties and have been widely used in important fields such as aerospace equipment, high-precision instruments and meters, etc. In the application process, the permanent magnet material as a magnetic field source is required to provide a stable and reliable magnetic field under various service conditions to realize the stable operation of the equipment.

[0003] At present, among the rare earth permanent magnet materials, the neodymium-iron-boron permanent magnet material has the highest magnetic energy product, but has poor temperature stability, and the use temperature is usually below 200 DEG C. Although the comprehensive performance of the magnetic properties and temperature stability of the samarium-cobalt permanent magnet material is good, the stable service temperature and the temperature coefficient are still relatively large, and it is difficult to meet the application requirements of high stability and high-temperature-service reliability of the permanent magnet material for high-end equipment.

[0004] Magnetic bodies with small temperature coefficients and magnetic flux changes have high-temperature stability. Existing research shows that the rare earth permanent magnet material can reduce the temperature coefficient of the magnetic body by adding heavy rare earth elements to form heavy rare earth / transition metal intermetallic compounds. For example, by adding heavy rare earth elements to replace the metal samarium element in the samarium-cobalt magnet, the temperature coefficient of the residual magnetism is reduced from about -0.035% / DEG C to better than -0.01% / DEG C in the range from room temperature to 100 DEG C, but too much heavy rare earth addition will significantly reduce the residual magnetism and coercive force of the magnetic body, causing the performance of the magnetic body to drop sharply, and cannot meet the requirements of a higher temperature range.

[0005] In order to improve the temperature resistance of the magnetic body, the proportion of iron and cobalt elements in the magnetic body can be adjusted to obtain a higher Curie temperature, thereby improving the high-temperature stability of the magnetic body. However, a high proportion of cobalt elements will also cause the performance of the magnetic body to decrease, and the temperature coefficient remains at a high level, which cannot meet the requirements of low reversible magnetic loss at high temperature. At the same time, the single design of the composition and particle size in the preparation process of the magnetic body makes the performance and stability of the magnetic body not high, and it is difficult to obtain a magnetic body with excellent comprehensive magnetic properties in a high-service-temperature-range environment. SUMMARY

[0006] In view of the above analysis, the embodiments of the present application aim to provide a high-temperature-stability rare earth cobalt permanent magnet material and a preparation method, to solve at least one of the problems of poor temperature stability, large temperature coefficient and magnetic flux change of the existing permanent magnet material.

[0007] In one aspect, the embodiment of the present application provides a high temperature stability rare earth cobalt permanent magnet material, which is prepared by compounding A alloy and B alloy according to mass ratio, wherein the mass ratio of the A alloy is 50% to 80%; the A alloy comprises 2 to 4 rare earth elements, wherein the content of Gd element in the rare earth elements is not less than 50%; and the B alloy comprises 2 to 4 rare earth elements, wherein the content of Sm element in the rare earth elements is not less than 80%.

[0008] Preferably, the chemical composition of the A alloy is (Gd a Dy b Er c Sm 1-a-b-c ) x Co y Cu z Zr w Fe 100-x-y-z-w , wherein the composition ratio of the rare earth elements is a=0.1 to 0.6, b=0 to 0.2, and c=0 to 0.1, and the mass percentage is x=22 to 25, y=45 to 50, z=6 to 11, and w=2 to 5.

[0009] Preferably, the chemical composition of the B alloy is (Gd a Dy b Er c Sm 1-a-b-c ) x Co y Cu z Zr w Fe 100-x-y-z-w , wherein the composition ratio of the rare earth elements is a=0.1 to 0.6, b=0 to 0.2, and c=0 to 0.1, and the mass percentage is x=25 to 28, y=55 to 60, z=6 to 11, and w=2 to 5.

[0010] Preferably, the performance of the high temperature stability permanent magnet material is that the remanence Br at room temperature 20℃ is greater than 8.7kGs, the knee point coercivity Hk is greater than 16KOe, and the temperature coefficient of the remanence Br in the temperature range of 20 to 300℃ is 0.015 to 0.025% / ℃.

[0011] In another aspect, the embodiment of the present application further provides a preparation method of a high temperature stability rare earth cobalt permanent magnet material.

[0012] S1, alloy smelting: ingredients are prepared according to the designed ratio of alloy elements, raw materials are smelted into A alloy ingots and B alloy ingots respectively by using a high vacuum induction smelting furnace, and the ingots are roughly broken into coarse powder particles not greater than 1mm;

[0013] S2, ball milling: the A and B alloy coarse powder particles obtained in S1 are ball milled into A alloy fine magnetic powder and B alloy fine magnetic powder;

[0014] S3, orientation compression: the A alloy fine magnetic powder and B alloy fine magnetic powder obtained in S2 are mixed according to a complex ratio, and then orientation compression is performed, and a magnet blank is obtained after compression;

[0015] S4, heat treatment: the magnet blank prepared in S3 is subjected to densification sintering and tempering heat treatment under vacuum conditions to obtain a permanent magnet material product.

[0016] Preferably, the particle size of the A alloy fine magnetic powder in S2 is 4.5-6.0 μm, and the particle size of the B alloy fine magnetic powder is 2.5-4.0 μm.

[0017] Specifically, the density of the magnet blank in S3 is 4.5-6.0 g / cm 3 .

[0018] Further, the densification sintering process in S4 is: the magnet blank is degassed at a high vacuum temperature below 500°C, pre-sintered by being heated to 1190-1210°C, and then sintered for 30-50 min, and then heated to 1220-1230°C for densification sintering, and then sintered for 40-70 min, and then high-purity argon is introduced to rapidly cool to 1170-1200°C for solid solution treatment for 1-3 h.

[0019] Exemplarily, the tempering heat treatment in S4 is: cooled to 820-870°C and held for 15-25 h, and then gradiently cooled to room temperature.

[0020] Further, the cooling rate of the gradiently cooling to room temperature in S4 is: the cooling rate in the high-temperature section is 0.7-0.9°C / min, and the cooling rate below 500°C is not less than 1.5°C / min.

[0021] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0022] 1. The present application obtains an alloy composition that can meet different temperature stability requirements through the high-use-temperature and low-temperature-coefficient rare earth / cobalt element composite addition of the alloy composition design, optimizes the content of rare earth elements, especially the Gd element, and the ratio of Fe / Co elements, realizes the regulation and control of the temperature characteristics, remanence and coercive force of the magnet, so that the permanent magnet material has high temperature resistance and maintains high knee point coercive force, and the prepared permanent magnet material has high use temperature and low reversible temperature coefficient, and exhibits excellent comprehensive magnetic properties, can meet the application requirements of high stability of the magnet in a wide temperature range, and is suitable for various high-precision magnetic sensors, high-temperature magnetic transmission and magnetic control devices, etc.

[0023] The two kinds of alloy fine magnetic powders A and B with different particle size distributions are compounded to prepare, the flowability of the magnetic powder and higher orientation degree can be considered, the sintering densification process is improved, the consistency of the material magnetic performance is improved, and the material magnetic performance is improved.

[0024] 2、The permanent magnet material preparation method adopts double particle size distribution and high green density, improves the uniformity of the magnet, does not need to control oxygen in the preparation process, maintains high oxygen content, combines reasonable design of the heat treatment process, promotes the formation of the temperature-resistant micro-magnetic structure of the magnet, and reduces the loss of the magnetic performance under the high temperature application condition of the magnet.

[0025] 3、The high temperature stability rare earth cobalt permanent magnet material prepared by optimizing the design of the heat treatment process has excellent temperature resistance and low magnetic loss change in a wide temperature range.

[0026] 4、Through the component design of high rare earth / cobalt element composite addition and process regulation, the prepared permanent magnet material has high comprehensive magnetic performance, high temperature resistance and magnetic stability, the use temperature is above 300 DEG C, the temperature coefficient is 0.015-0.025 % / C in a wide temperature range from room temperature 20 DEG C to 300 DEG C, the high-low temperature cycle impact magnetic loss is less than 1.5 %, compared with the existing permanent magnet material, high temperature stability is realized, and high magnetic performance is maintained.

[0027] In the present application, the above technical solutions can be combined with each other to realize more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purposes and other advantages of the present application can be realized and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application.

[0029] Figure 1 It is the magnetic performance test curve of the permanent magnet material at room temperature in the embodiment 2 of the present application.

[0030] Figure 2 It is the magnetic performance test curve of the permanent magnet material at 300 DEG C in the embodiment 2 of the present application.

[0031] Figure 3 It is the scanning electron microscope image of the permanent magnet material. DETAILED DESCRIPTION

[0032] Preferred embodiments of the present application will be described in detail below with reference to the drawings, in which:

[0033] In one aspect, one specific embodiment of the present application discloses a high temperature stability rare earth cobalt permanent magnet material, which is prepared by compounding A alloy and B alloy in mass ratio, wherein the mass ratio of the A alloy is 50% to 80%; the A alloy comprises 2 to 4 rare earth elements, and the content of Gd element in the rare earth elements is not less than 50%; the B alloy comprises 2 to 4 rare earth elements, and the content of Sm element in the rare earth elements is not less than 80%.

[0034] The content of Gd element in the A alloy is not less than 50%, which can significantly reduce the temperature coefficient of the alloy and improve the temperature resistance; the content of Sm element in the B alloy is not less than 80%, the ratio design of Sm and Fe / Co can improve the remanence and intrinsic coercivity of the magnet, optimize the knee point coercivity, thereby enhancing the temperature resistance and demagnetization resistance of the magnet; the comprehensive characteristics of the rare earth elements and the ferromagnetic elements are fully utilized, and high temperature resistance, high coercivity and good chemical stability are realized.

[0035] The chemical composition of the A alloy is (Gd a Dy b Er c Sm 1-a-b-c ) x Co y Cu z Zr w Fe 100-x-y-z-w , wherein the composition ratio of the rare earth elements is a=0.1 to 0.6, b=0 to 0.2, and c=0 to 0.1, and the mass percentage is x=22 to 25, y=45 to 50, z=6 to 11, and w=2 to 5.

[0036] The chemical composition of the B alloy is (Gd a Dy b Er c Sm 1-a-b-c ) x Co y Cu z Zr w Fe 100-x-y-z-w , wherein the composition ratio of the rare earth elements is a=0.1 to 0.6, b=0 to 0.2, and c=0 to 0.1, and the mass percentage is x=25 to 28, y=55 to 60, z=6 to 11, and w=2 to 5.

[0037] The high temperature stability permanent magnet material is prepared by double-alloy compounding, alloy composition design is used to obtain alloy composition meeting different temperature stability requirements, the ratio of rare earth elements and Fe / Co elements is optimized to control the temperature characteristics, remanence and coercive force of the magnet, so that the permanent magnet material has high temperature resistance and maintains high knee point coercive force.

[0038] As shown in Figure 3 The high temperature stability permanent magnet material has no micro defects such as cracks or holes, and has a dense microstructure.

[0039] The high temperature stability permanent magnet material has the following properties: remanence Br is greater than 8.7 kGs at room temperature 20℃, knee point coercive force Hk is greater than 16 KOe, and the temperature coefficient of remanence Br is 0.015-0.025% / ℃ in the temperature range of 20-300℃.

[0040] In one aspect, one specific embodiment of the present application discloses a preparation method of a high temperature stability rare earth cobalt permanent magnet material, comprising the following steps:

[0041] S1, alloy smelting: ingredients are prepared according to the designed ratio of alloy elements, raw materials are smelted into A alloy ingots and B alloy ingots by using a high vacuum induction smelting furnace, and the ingots are coarsely crushed into coarse powder particles not greater than 1mm;

[0042] S2, ball milling: the A alloy coarse powder particles and the B alloy coarse powder particles obtained in S1 are ball milled into A alloy fine magnetic powder and B alloy fine magnetic powder;

[0043] S3, orientation molding: the A alloy fine magnetic powder and the B alloy fine magnetic powder obtained in S2 are mixed according to a compounding ratio, and then orientation molding is performed, so that a magnet blank is obtained after molding;

[0044] S4, heat treatment: the magnet blank is subjected to densification sintering and tempering heat treatment under vacuum conditions, so that a permanent magnet product is obtained.

[0045] In S2, the particle size of the A alloy fine magnetic powder is 4.5-6.0μm, and the particle size of the B alloy fine magnetic powder is 2.5-4.0μm. Specifically, the particle size of the A alloy fine magnetic powder is 4.5μm, 4.6μm, 4.7μm, 4.8μm, 5.1μm, 5.5μm, 5.8μm or 6.0μm; and the particle size of the B alloy fine magnetic powder is 2.5μm, 2.8μm, 3.6μm, 3.9μm or 4.0μm.

[0046] The finer the particle size of the magnetic powder, the worse the flowability of the magnetic powder; and the larger the particle size of the magnetic powder, the worse the adaptability to the orientation compression process, the lower the compactness of the magnet blank after compression, and the lower the quality of the permanent magnet material product; the use of two kinds of alloy fine magnetic powders A and B with different particle size distributions for composite preparation can take into account the flowability of the magnetic powder and obtain higher orientation degree, improve the sintering densification process, and help the consistency of the magnet performance, thereby improving the magnetic performance of the material.

[0047] Preferably, the ball milling process adopts an inert protective medium to prevent the magnetic powder from contacting air, and a single diameter steel ball is used in the ball milling process to more accurately control the particle size distribution of the powder in the ball milling process.

[0048] The magnet blank density in S3 is 4.5-6.0 g / cm 3 A higher compacted blank density can promote magnet densification, improve the orderliness of magnetic powder orientation arrangement, reduce the hole and shrinkage deformation rate, and improve the consistency of the sintered magnet.

[0049] The heat treatment process in S4 is performed in a vacuum heat treatment furnace.

[0050] The densification sintering process in S4 is: the magnet blank is degassed at a high vacuum temperature below 500℃, heated to 1190-1210℃ for pre-sintering, the pre-sintering time is 30-50 min, then heated to 1220-1230℃ for densification sintering, the sintering holding time is 40-70 min; after densification sintering, high-purity argon is introduced for rapid cooling to 1170-1200℃ for solid solution treatment for 1-3 h.

[0051] During the sintering process, the particles of the two kinds of alloy A and B combine with each other through diffusion and flow to form a precursor phase structure; the use of two kinds of alloy fine magnetic powders A and B with different particle size distributions for composite preparation can take into account the flowability of the magnetic powder and obtain higher orientation degree, and improve the density of the precursor phase during the sintering process;

[0052] Pre-sintering before densification sintering helps to achieve better densification effect during high-temperature sintering, improve the density of the sintered body, and reduce impurities and unevenness at the grain boundaries.

[0053] The tempering heat treatment in S4 is: cooling to 820-870℃ for 15-25 h, and then gradient slow cooling to room temperature.

[0054] The cooling rate of the gradient slow cooling to room temperature during the tempering heat treatment process is: the cooling rate in the high-temperature section is 0.7-0.9℃ / min, and the cooling rate below 500℃ is not less than 1.5℃ / min.

[0055] The permanent magnet material product obtained in S4 has an oxygen content of 2800-3800 ppm, i.e. the preparation process does not need to control the oxygen content, and a certain oxygen content is helpful to the stability of the magnet process when the rare earth cobalt permanent magnet material product is prepared.

[0056] The permanent magnet material product obtained in S4 has a magnetic flux change rate of less than 1.5% under high and low temperature impact in a temperature range of 20-300 DEG C.

[0057] In summary, the rare earth / cobalt element composite addition component design is combined with process control to prepare the permanent magnet material with high temperature resistance and magnetic stability, the use temperature is above 300 DEG C, and the temperature coefficient is 0.015-0.025% / DEG C in a wide temperature range from room temperature 20 DEG C to 300 DEG C, the high and low temperature cycle impact magnetic loss is less than 1.5%, compared with the existing permanent magnet material, high temperature stability is realized, and high magnetic performance is maintained.

[0058] The high temperature stability rare earth cobalt permanent magnet material and the preparation method thereof will be described below in combination with specific examples.

[0059] Example 1

[0060] The embodiment provides a high temperature stability rare earth cobalt permanent magnet material and a preparation method thereof.

[0061] The chemical composition of the A alloy is (Gd 0.6 Sm 0.4 ) 22.6 Co 48.5 Cu6Zr 4.7 Fe 18.2 The chemical composition of the B alloy is (Dy 0.2 Sm 0.8 ) 27.6 Co 56 Cu 7.5 Zr 2.2 Fe 6.7 .

[0062] The specific preparation process is as follows:

[0063] S1, alloy smelting: A and B two kinds of alloy raw materials are prepared according to the element design proportion, and are smelted and cast into A alloy ingot and B alloy ingot in a high vacuum vacuum induction smelting furnace, and the weight of a single alloy ingot is about 30 kg;

[0064] S2, ball milling: the A and B alloy ingots are respectively coarsely broken into coarse powder particles not more than 1 mm, and then put into a ball mill to finely grind into fine magnetic powder meeting the requirements, inert protective medium is used in the powdering process to prevent the magnetic powder from contacting air, single-diameter steel balls are used in the ball milling process, the ball milling time is adjusted to control the average particle size of the A alloy powder to be 4.6 μm and the average particle size of the B alloy powder to be 2.8 μm;

[0065] S3, orientation molding: the obtained two kinds of alloy magnetic powders are uniformly mixed according to the proportion that the A alloy and the B alloy each account for 50% of the weight, and then put into an orientation molding press for one-time high-pressure orientation molding, and the high-stability rare earth cobalt magnet blank obtained after molding has a density of 4.5-4.7 g / cm 3 ;

[0066] S4, heat treatment: the magnet blank is put into a vacuum heat treatment furnace for densification sintering and tempering heat treatment, and the main process steps include: degassing of the magnet blank at a high vacuum temperature below 500 ℃, pre-sintering at a temperature of 1197-1203 ℃, pre-sintering for about 30 min, then densification sintering treatment at a temperature of 1223-1228 ℃, heat preservation for 40-50 min, then rapid cooling to 1183-1200 ℃ for solid solution treatment for 1 h, then cooling to 845-860 ℃ for heat preservation for 20-25 h, and then gradient slow cooling to room temperature, the cooling speed at the high temperature section is 0.7-0.9 ℃ / min, and the cooling speed below 500 ℃ is not less than 1.5 ℃ / min, and the blank is taken out from the heat treatment furnace to obtain the high-temperature-stability rare earth cobalt permanent magnet material of the application.

[0067] The permanent magnet material blank obtained in S4 is sampled for performance testing according to the testing standard, and the magnetic performance data of the sample at room temperature 20 ℃ and high temperature 300 ℃ are tested by using a permanent magnet demagnetization curve measuring instrument, as shown in Table 1.

[0068] The high and low temperature magnetic flux changes and oxygen content are detected by using a fluxmeter and an oxygen content analyzer, and the results are shown in Table 1.

[0069] The permanent magnet material prepared by using the application has excellent high-temperature stability.

[0070] Example 2

[0071] The application provides a high-temperature-stability rare earth cobalt permanent magnet material and a preparation method thereof.

[0072] The chemical composition of the A alloy is (Gd 0.5 Dy 0.1 Sm 0.4 ) 24.9 Co 50 Cu 8.2 Zr 3.8 Fe 13.1, B alloy chemical composition is (Gd 0.05 Sm 0.95 ) 25.9 Co 59.2 Cu 6.2 Zr 2.6 Fe 6.1 .

[0073] The specific preparation process is as follows:

[0074] S1, alloy smelting: according to the design proportion of elements, A and B alloy raw materials are prepared respectively, and are smelted and cast into A alloy ingot and B alloy ingot in a high vacuum vacuum induction melting furnace, and the weight of a single alloy ingot is about 30 kg;

[0075] S2, ball milling: the A and B alloy ingots are respectively roughly broken into coarse powder particles not greater than 1 mm, and then are put into a ball mill to be finely ground into fine magnetic powder meeting the requirements, inert protective medium is used in the powder preparation process to prevent the magnetic powder from contacting air, and single diameter steel balls are used in the ball milling process, the ball milling time is adjusted to control the average particle size of the A alloy powder to be 4.7 μm and the average particle size of the B alloy powder to be 3.6 μm;

[0076] S3, orientation molding: the obtained two kinds of alloy magnetic powders are uniformly mixed according to the proportion that the A alloy accounts for 80% and the B alloy accounts for 20%, and are put into an orientation molding press for one-time high pressure orientation molding, and the high-stability rare earth cobalt magnet blank obtained after molding has a density of 4.6-4.9 g / cm 3 ;

[0077] S4, heat treatment: the magnet blank is put into a vacuum heat treatment furnace for densification sintering and tempering heat treatment, and the main process steps include: the magnet blank is degassed at a high vacuum temperature below 500 DEG C, is heated to 1192-1197 DEG C for pre-sintering, the pre-sintering time is about 40 min, then is heated to 1221-1226 DEG C for densification sintering treatment, is kept warm for 60-70 min, is then cooled to 1175-1190 DEG C for solid solution treatment for 3 h, is further cooled to 835-850 DEG C for keeping warm for 15-20 h, and then is gradiently cooled to room temperature, the cooling speed in the high temperature section is 0.7-0.9 DEG C / min, and the cooling speed below 500 DEG C is not less than 1.5 DEG C / min, the blank is taken out from the heat treatment furnace, and the high temperature stability rare earth cobalt permanent magnet material of the application is prepared.

[0078] The permanent magnet material blank obtained in S4 is sampled for performance test according to the test standard, and the magnetic performance data of the sample at room temperature 20 DEG C and high temperature 300 DEG C are measured by using a permanent magnet demagnetization curve measuring instrument, and the data are shown in Table 1.

[0079] The high and low temperature magnetic flux change and oxygen content are detected by using a fluxmeter and an oxygen content analyzer, and the results are shown in Table 1.

[0080] The permanent magnet material prepared by the application exhibits excellent high temperature stability.

[0081] The demagnetization curves of the permanent magnet material of the embodiment at 300℃ and at room temperature are shown in Figure 1 and Figure 2 respectively.

[0082] Embodiment 3

[0083] The embodiment provides a high temperature stability rare earth cobalt permanent magnet material and a preparation method thereof.

[0084] The chemical composition of the A alloy is (Gd 0.55 Er 0.05 Sm 0.4 ) 24.3 Co 46 Cu 10.5 Zr 4.1 Fe 15.1 The chemical composition of the B alloy is (Dy 0.05 Er 0.1 Sm 0.85 ) 26.1 Co 55 Cu8Zr 3.6 Fe 7.3 .

[0085] The specific preparation process is as follows:

[0086] S1, alloy smelting: prepare A and B two kinds of alloy raw materials according to the designed proportion of elements, smelt and cast into A alloy ingot and B alloy ingot in a high vacuum vacuum induction smelting furnace, and the weight of a single alloy ingot is about 30 kg;

[0087] S2, ball milling: respectively crush A and B alloy ingots into coarse powder particles not greater than 1 mm, and then put them into a ball mill to finely grind into required fine magnetic powder, inert protective medium is used in the powder preparation process to prevent the magnetic powder from contacting with air, single diameter steel balls are used in the ball milling process, the ball milling time is adjusted to control the average particle size of A alloy powder to be 5.1 μm and the average particle size of B alloy powder to be 3.9 μm;

[0088] S3, orientation molding: uniformly distribute and mix the obtained two kinds of alloy magnetic powder according to the proportion of A alloy accounting for 75% and B alloy accounting for 25% by weight, and put them into an orientation molding press for one-time high pressure orientation molding, and the high stability rare earth cobalt magnet blank obtained after molding has a density of 4.8-5.1 g / cm 3 ;

[0089] S4, heat treatment: the magnet blank is put into a vacuum heat treatment furnace for densification sintering and tempering heat treatment, and main steps of the process include: the magnet blank is degassed at a high vacuum temperature of 500 DEG C or below, heated to 1192-1197 DEG C for pre-sintering, pre-sintering for about 40 min, then heated to 1221-1226 DEG C for densification sintering, kept for 60-70 min, then high-purity argon is introduced to rapidly cool to 1175-1190 DEG C for solid solution treatment for 3 h, then cooled to 835-850 DEG C for 15-20 h, then gradiently slow-cooled to room temperature, the cooling speed at the high temperature section is 0.7-0.9 DEG C / min, and the cooling speed below 500 DEG C is not less than 1.5 DEG C / min, the blank is taken out from the heat treatment furnace, and the high temperature stability rare earth cobalt permanent magnet material of the application is obtained.

[0090] The permanent magnet material blank obtained in S4 is sampled for performance test according to the test standard, and the magnetic performance data of the sample at room temperature 20 DEG C and high temperature 300 DEG C are tested by a permanent magnet demagnetization curve measuring instrument, as shown in Table 1.

[0091] The high and low temperature magnetic flux change and oxygen content are detected by a fluxmeter and an oxygen content analyzer, and the results are shown in Table 1.

[0092] The permanent magnet material prepared by the application has excellent high temperature stability.

[0093] Comparative Example 1

[0094] The embodiment provides a rare earth cobalt permanent magnet material and a preparation method thereof.

[0095] The specific preparation process is the same as that of Example 1, and the difference lies in that only A alloy is used.

[0096] The permanent magnet material blank obtained in S4 is sampled for performance test according to the test standard, and the magnetic performance data of the sample at room temperature 20 DEG C and high temperature 300 DEG C are tested by a permanent magnet demagnetization curve measuring instrument, as shown in Table 1.

[0097] The high and low temperature magnetic flux change and oxygen content are detected by a fluxmeter and an oxygen content analyzer, and the results are shown in Table 1.

[0098] Comparative Example 2

[0099] The embodiment provides a rare earth cobalt permanent magnet material and a preparation method thereof.

[0100] The specific preparation process is the same as that of Example 1, and the difference lies in that the proportion of A alloy is 40%.

[0101] The permanent magnet material blank obtained in S4 is sampled for performance test according to the test standard, and the magnetic performance data of the sample at room temperature 20 DEG C and high temperature 300 DEG C are tested by a permanent magnet demagnetization curve measuring instrument, as shown in Table 1.

[0102] The high and low temperature magnetic flux changes and oxygen content were detected by a fluxmeter and an oxygen content analyzer, and the results are shown in Table 1.

[0103] Comparative Example 3

[0104] The present embodiment provides a rare earth cobalt permanent magnet material and a preparation method thereof.

[0105] The specific preparation process is the same as that of Example 1, except that the average particle sizes of the A and B alloys are 8 μm and 5 μm, respectively.

[0106] The permanent magnet material blanks obtained were sampled according to the test standards for performance testing, and the magnetic performance data of the samples at room temperature 20℃ and high temperature 300℃ were tested by a permanent magnet demagnetization curve measuring instrument, as shown in Table 1.

[0107] The high and low temperature magnetic flux changes and oxygen content were detected by a fluxmeter and an oxygen content analyzer, and the results are shown in Table 1.

[0108] Comparative Example 4

[0109] The present embodiment provides a rare earth cobalt permanent magnet material and a preparation method thereof.

[0110] The specific preparation process is the same as that of Example 1, except that pre-sintering is not performed in S4.

[0111] The permanent magnet material blanks obtained were sampled according to the test standards for performance testing, and the magnetic performance data of the samples at room temperature 20℃ and high temperature 300℃ were tested by a permanent magnet demagnetization curve measuring instrument, as shown in Table 1.

[0112] The high and low temperature magnetic flux changes and oxygen content were detected by a fluxmeter and an oxygen content analyzer, and the results are shown in Table 1.

[0113] Table 1: Performance test data of permanent magnet materials of examples and comparative examples

[0114]

[0115] The greater the remanence (Br) and knee point coercivity (Hk), the better the magnetic field retention ability and demagnetization resistance of the permanent magnet material, and the smaller the remanence temperature coefficient and high and low temperature impact magnetic flux change rate, indicating that the performance of the magnet is more stable under different temperature conditions.

[0116] As shown in Table 1, Examples 1-3 adopt the double-alloy composite of the present application, the alloy component composition and content meet the requirements of the present application, and the prepared permanent magnet material exhibits excellent comprehensive magnetic performance, has high use temperature and low reversible temperature coefficient, large remanence (Br) and knee point coercivity (Hk), and small remanence temperature coefficient and high and low temperature impact magnetic flux change rate; and the preparation process does not need to control the oxygen content. The comprehensive magnetic performance of the permanent magnet materials of Comparative Examples 1-4 is poorer than that of Examples 1-3, and the specific conditions are as follows:

[0117] Compared with Example 1, only A alloy is used in Comparative Example 1, which results in low Sm content and high Fe / Co ratio in the permanent magnet material, and the remanence of the obtained permanent magnet material is reduced, the knee point coercivity Hk is reduced more, and the demagnetization resistance is significantly reduced;

[0118] Compared with Example 1, the A alloy is used in a proportion of 40% in Comparative Example 2, which results in low Gd content in the permanent magnet material, and the temperature coefficient of the remanence Br is increased, the temperature resistance of the obtained permanent magnet material is poor, and the high and low temperature impact magnetic flux change rate is significantly increased;

[0119] Compared with Example 1, the magnetic powder particle sizes of A and B alloys are large in Comparative Example 3, and the compactness of the obtained magnet blank is low after compaction, and there are pores in the magnet blank, which reduces the remanence (Br) and the knee point coercivity (Hk) of the magnet;

[0120] Compared with Example 1, pre-sintering is not performed during heat treatment in Comparative Example 4, and the compactness effect after sintering is slightly poor, and the remanence (Br) and the knee point coercivity (Hk) are reduced.

[0121] In summary, the high rare earth / cobalt element composite addition composition design is combined with process control to prepare the permanent magnet material with high comprehensive magnetic properties, and the permanent magnet material has high temperature resistance and magnetic stability, the remanence Br at room temperature 20℃ is greater than 8.7kGs, the knee point coercivity Hk is greater than 16KOe, and the remanence Br temperature coefficient in the temperature range of 20-300℃ is 0.015-0.025% / ℃.

[0122] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A high temperature stable rare earth cobalt permanent magnet material, characterized in that, The high temperature stability rare earth cobalt permanent magnet material is prepared by compounding A alloy and B alloy according to mass proportions, wherein the mass proportion of the A alloy is 50% to 80%; the A alloy comprises 2 to 4 rare earth elements, wherein the content proportion of Gd element in the rare earth elements is not less than 50%; the B alloy comprises 2 to 4 rare earth elements, wherein the content of Sm element in the rare earth elements is not less than 80%. The chemical composition of the A alloy is (Gd a Dy b Er c Sm 1-a-b-c ) x Co y Cu z Zr w Fe 100-x-y-z-w , wherein the rare earth element composition ratio: a=0.1~0.6, b=0~0.2, c=0~0.1, mass percentage: x=22~25, y=45~50, z=6~11, w=2~5; The chemical composition of the B alloy is (Gd a Dy b Er c Sm 1-a-b-c ) x Co y Cu z Zr w Fe 100-x-y-z-w , wherein the rare earth element composition ratio: a = 0.1~0.6, b = 0~0.2, c = 0~0.1, mass percentage: x = 25~28, y = 55~60, z = 6~11, w = 2~5.

2. The permanent magnetic material of claim 1, wherein, The performance of the high temperature stability rare earth cobalt permanent magnet material is as follows: the remanence Br at room temperature 20 DEG C is greater than 8.7 kGs, the knee point coercivity Hk is greater than 16 KOe, and the remanence Br temperature coefficient in the temperature range of 20 to 300 DEG C is 0.015 to 0.025% / DEG C.

3. A method for producing a high temperature stable rare earth cobalt permanent magnet material, characterized by, The method for preparing the permanent magnet material of any one of claims 1 to 2 comprises the following steps: S1, alloy smelting: ingredients are prepared according to the designed proportions of alloy elements, raw materials are smelted into A alloy ingots and B alloy ingots by using a high vacuum induction smelting furnace, and the ingots are coarsely broken into coarse powder particles not greater than 1 mm; S2, ball milling: the A alloy coarse powder particles and the B alloy coarse powder particles obtained in S1 are ball milled into A alloy fine magnetic powder and B alloy fine magnetic powder; S3, orientation compression: the A alloy fine magnetic powder and the B alloy fine magnetic powder obtained in S2 are mixed according to the compounding proportions, and then orientation compression is performed, so that a magnet blank is obtained after compression; S4, heat treatment: the magnet blank prepared in S3 is subjected to densification sintering and tempering heat treatment under vacuum conditions, so that a permanent magnet material product is obtained.

4. The production method according to claim 3, characterized by, In S2, the particle size of the A alloy fine magnetic powder is 4.5 to 6.0 μm, and the particle size of the B alloy fine magnetic powder is 2.5 to 4.0 μm.

5. The preparation method according to claim 3, characterized in that, The magnet blank density described in S3 is 4.5-6.0 g / cm3 3 .

6. The preparation method according to claim 3, characterized in that, In S4, the densification sintering process is as follows: the magnet blank is degassed at a high vacuum temperature of 500 DEG C or lower, pre-sintered by being heated to 1190 to 1210 DEG C, and then sintered by being heated to 1220 to 1230 DEG C for 40 to 70 min, and then high-purity argon is introduced to rapidly cool the magnet blank to 1170 to 1200 DEG C for solid solution treatment for 1 to 3 h.

7. The preparation method according to claim 3, characterized in that, In S4, the tempering heat treatment is as follows: the magnet blank is cooled to 820 to 870 DEG C for 15 to 25 h, and then gradiently cooled to room temperature.

8. The production method according to claim 7, characterized by, In S4, the cooling speed of the gradiently cooling to room temperature is as follows: the cooling speed in the high temperature section is 0.7 to 0.9 DEG C / min, and the cooling speed at 500 DEG C or lower is not less than 1.5 DEG C / min.

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