A kind of neodymium iron boron magnetic material and preparation method thereof

Abstract

The present application relates to the technical field of NdFeB preparation, more specifically, it relates to a NdFeB magnetic material and a preparation method thereof, including the following raw materials: praseodymium-neodymium alloy, gadolinium-iron alloy, cerium, ferroboron, copper, aluminum, titanium, cobalt, antioxidant, auxiliary material, high temperature resistant agent, the balance is iron, the auxiliary material is composed of yttrium-samarium alloy, lanthanum-nickel-cobalt alloy, and the high temperature resistant agent is at least two of nano silicon carbide, gallium, and manganese-aluminum-carbon alloy; the preparation method comprises the following steps, the above raw materials are mixed, smelted, a smelting liquid is obtained, the obtained smelting liquid is cast for stripping, and a stripping sheet is obtained; the stripping sheet is subjected to hydrogen crushing and crushing to obtain hydrogen crushing powder; the hydrogen crushing powder is pressed, magnetized, and demagnetized in a forming mold to obtain a raw magnet; the raw magnet is sintered, tempered, and cooled at 1100-1250°C. The NdFeB magnetic material prepared in the present application has good temperature stability.

Description

Technical Field

[0001] The present application relates to the technical field of NdFeB preparation, and more specifically, to a NdFeB magnetic material and a preparation method thereof. Background Art

[0002] Sintered NdFeB permanent magnet is the permanent magnet material with the best comprehensive magnetic properties today. In 2007, its magnetic energy product has increased from 279 kJ / m in 1983 to 3 Increased to 474 kJ / m 3 Compared with bonded, injection molded and cast NdFeB, sintered NdFeB permanent magnets are widely used in high-performance micro motors, nuclear magnetic resonance, aerospace navigators, electric vehicles, electronic information industry and other high-tech fields due to their higher remanence and coercive force, excellent mechanical properties and relatively low price. At the same time, they also have great application potential in many emerging fields such as magnetic levitation bearings, maglev trains and wind turbines.

[0003] Although NdFeB magnets have high magnetic properties, their Curie temperature (310℃) is low and their temperature coefficient is high. NdFeB has a low Curie temperature (312℃) and is extremely sensitive to temperature. When heated, its remanence, especially its intrinsic coercivity, decreases rapidly, and its magnetic temperature coefficient is very large. For example, the maximum operating temperature of sintered NdFeB magnets with Hcj of about 12kOe is generally 80℃. In other words, this type of magnet will basically lose its magnetism after being soaked in freshly boiled water.

[0004] In order to improve the temperature stability of NdFeB magnets, heavy rare earth elements such as dysprosium and terbium are generally added to increase the magnetocrystalline anisotropy field of the main phase, thereby improving the stability of the obtained NdFeB magnets.

[0005] The above-mentioned related technologies also have the following problems: adding heavy rare earth elements such as dysprosium and terbium to improve the temperature stability of NdFeB magnetic materials has poor effect and high cost. Summary of the invention

[0006] In order to improve the temperature stability of NdFeB magnetic materials, the present application provides a NdFeB magnetic material and a preparation method thereof.

[0007] In the first aspect, the present application provides a neodymium iron boron magnetic material, which adopts the following technical solution:

[0008] A neodymium iron boron magnetic material comprises the following raw materials in weight percentage: 19-21% of praseodymium neodymium alloy, 1-2% of gadolinium iron alloy, 5-10% of cerium, 0.5-1% of ferroboron, 0.1-0.5% of copper, 0.2-0.5% of aluminum, 0.1-0.5% of titanium, 0.1-0.5% of cobalt, 0.1-0.5% of antioxidant, 1-2% of auxiliary material, 1-2% of high temperature resistant agent, and the balance is iron. The auxiliary material is composed of yttrium samarium alloy and lanthanum nickel cobalt alloy in a mass ratio of (3-5):(3-5), and the high temperature resistant agent is at least two of nano silicon carbide, gallium, and manganese aluminum carbon alloy.

[0009] By adopting the above technical scheme, the present application adds antioxidants, auxiliary materials and high temperature resistant agents. The addition of high temperature resistant agents is convenient for improving the high temperature resistance of NdFeB magnetic materials. The auxiliary materials are used to cooperate with the high temperature resistant agents to improve the anisotropy of NdFeB magnetic materials, so as to improve the coercive force of NdFeB magnetic materials. At the same time, the addition of high temperature resistant agents is convenient for improving the high temperature resistance of NdFeB magnetic materials. At the same time, in combination with antioxidants, on the basis of improving the high temperature resistance of NdFeB magnetic materials, the preparation process of NdFeB magnetic materials is further improved. Anti-oxidation property: the yttrium-samarium alloy in the auxiliary material reduces the remanence temperature coefficient and coercivity temperature coefficient of the NdFeB magnetic material, thereby reducing the adverse effects of temperature increase on the remanence and coercivity of the magnetic material; the lanthanum-nickel-cobalt alloy has a higher Curie temperature and coercivity; the manganese-aluminum-carbon alloy in the high-temperature resistant agent has better anti-oxidation and high-temperature resistance; nano-silicon carbide has a higher melting point, and gallium is convenient for improving the coercivity and maximum operating temperature of the NdFeB magnetic material. The auxiliary material and the high-temperature resistant agent cooperate with each other to improve the high-temperature resistance of the NdFeB magnetic material.

[0010] Preferably, the mass ratio of the antioxidant, auxiliary material and high temperature resistant agent is (0.2-0.4):(1.5-1.9):(1.2-1.4).

[0011] By adopting the above technical scheme, the addition amounts of the three components of antioxidant, auxiliary material and high temperature resistant agent are adjusted so that the ratio of the three components can be optimized. The antioxidant can reduce the oxidation of rare earth elements in the auxiliary material and the high temperature resistant agent during the heating process, thereby improving the coercive force of the obtained NdFeB magnetic material. The auxiliary material and the antioxidant cooperate with each other to improve the high temperature resistance and magnetic properties of the NdFeB magnetic material, thereby improving the temperature stability of the obtained NdFeB magnetic material.

[0012] Preferably, the high temperature resistant agent is composed of nano silicon carbide, gallium, and manganese aluminum carbon alloy in a mass ratio of (3-5):(3-6):(1-2).

[0013] By adopting the above technical scheme, the high temperature resistant agent is obtained by compounding three components of nano silicon carbide, gallium, and manganese aluminum carbon alloy, and the ratio of the three components is optimized to facilitate improving the high temperature resistance of the high temperature resistant agent in the NdFeB magnetic material. The addition of gallium can increase the Curie temperature and coercive force of the NdFeB magnetic material; the manganese aluminum carbon alloy has better antioxidant and high temperature resistance; nano silicon carbide has a high melting point and is convenient to be used as a supporting point, thereby reducing the contact and growth of other materials in the NdFeB magnetic material during the sintering process, thereby improving the high temperature resistance of the high temperature resistant agent.

[0014] Preferably, the nano silicon carbide is pretreated silicon carbide, and the preparation method of the pretreated silicon carbide comprises the following steps: adding silicon carbide powder to a NaOH solution, mixing, washing to neutrality and drying to obtain silicon carbide powder one; adding a silane coupling agent to toluene to obtain a mixed solution, then adding silicon carbide powder one to the mixed solution, stirring for reaction, filtering, and obtaining silicon carbide powder two; washing silicon carbide powder two with acetone, vacuum filtering, and drying to constant weight to obtain.

[0015] Preferably, the preparation method of pretreated silicon carbide comprises the following steps: adding silicon carbide powder to a 0.11 g / mL NaOH solution, stirring at a constant temperature of 90°C for 4 hours, then washing to neutrality and drying to obtain silicon carbide powder 1; adding silane coupling agent KH550 to 300 ml of toluene to obtain a mixed solution, then adding 50 g of silicon carbide powder 1 to the mixed solution, stirring at a constant temperature of 90°C for 4 hours, filtering after the reaction is completed, and obtaining silicon carbide powder 2. The silicon carbide powder 2 is fully washed with acetone, vacuum filtered and dried to constant weight.

[0016] By adopting the above technical solution, the fine-grained silicon carbide micropowder particles have a large specific surface area and high surface energy, and tend to agglomerate with each other to reduce their surface energy. The alkoxy group in the silane coupling agent reacts with the mono-OH group on the surface of the silicon carbide micropowder and is coated on the surface of the silicon carbide micropowder, which is convenient for effectively reducing the agglomeration between particles.

[0017] Preferably, the pretreated silicon carbide is modified nano pretreated silicon carbide, and the preparation method of the modified nano pretreated silicon carbide comprises the following steps: plating a layer of lanthanum-cerium alloy on the surface of the pretreated nano silicon carbide by vacuum electroplating, so that the silicon carbide has a core-shell structure.

[0018] By adopting the above technical scheme, nano-silicon carbide has a higher melting point, which is convenient to be used as a supporting point, thereby reducing the contact and growth of different main phase grains during the sintering process. At the same time, the support of nano-silicon carbide powder at the grain boundary promotes the diffusion of lanthanum-cerium alloy at the grain boundary during sintering, expands the grain boundary phase, and then hardens the NdFeB magnet grains, thereby improving the coercive force of the NdFeB magnet and, at the same time, improving the high temperature resistance of the NdFeB magnet.

[0019] Preferably, the high temperature resistant agent is subjected to acidification and degreasing treatment.

[0020] By adopting the above technical scheme, after the high temperature resistant agent is acidified and degreased, it is convenient to reduce the influence of impurities on the raw materials, indirectly improve the coercive force and use temperature of the high temperature resistant NdFeB magnetic material, and then effectively improve the high temperature resistance of the NdFeB magnetic material.

[0021] Preferably, the antioxidant is composed of iridium nickel alloy and triethanolamine borate in a mass ratio of (5-7):(1-2).

[0022] Preferably, the iridium-nickel alloy contains 40% iridium and 60% nickel.

[0023] By adopting the above technical scheme, the antioxidant is obtained by compounding two components of iridium-nickel alloy and triethanolamine borate, and the ratio of the two components is adjusted to make the ratio of the two components optimal. The iridium and nickel in the iridium-nickel alloy have strong antioxidant ability, and the triethanolamine borate has anti-rust and antioxidant effects, which is convenient for coating on the surface of the NdFeB magnetic material to block oxygen, thereby reducing the oxidation of the NdFeB material during the sintering process.

[0024] In a second aspect, the present application provides a method for preparing a NdFeB magnetic material, using the following technical solution:

[0025] A method for preparing a NdFeB magnetic material comprises the following steps:

[0026] (1) Preparation of base material: the above raw materials are mixed and smelted to obtain a molten liquid, and the obtained molten liquid is cast and strip-spun to obtain a strip-spun sheet;

[0027] (2) crushing: subjecting the stripped pieces obtained in step (1) to hydrogen crushing to obtain hydrogen crushed powder;

[0028] (3) Orienting and pressing; pressing, magnetizing and demagnetizing the hydrogen-crushed powder obtained in step (2) in a molding die to obtain a raw magnet;

[0029] (4) Sintering: The green magnet obtained in step (3) is sintered at 1100-1250° C., tempered and cooled to obtain the raw magnet.

[0030] Preferably, the method further includes the following steps: (5) Preparation of corrosion-resistant layer: coating a corrosion-resistant layer on the surface of the NdFeB magnetic material obtained in step (4), wherein the thickness of the corrosion-resistant layer is 150-180 nm.

[0031] By adopting the above technical solution, the corrosion-resistant layer has better corrosion resistance, which is convenient for further improving the bonding strength of the magnet coating and the coercive force of the magnet.

[0032] Preferably, the density of the green magnet obtained in step (3) is 3.8-4 g / cm 3 .

[0033] By adopting the above technical solution, the density of the raw magnet is related to the tightness of the atomic arrangement inside the magnet. When the atoms are arranged more tightly, it is more difficult for the rare earth metal to diffuse into the magnet along the grain boundaries. When the atoms are arranged more loosely, the rare earth metal atoms are not in close contact with the neodymium at the grain boundaries, which is not conducive to the occurrence of the substitution reaction.

[0034] Preferably, the NdFeB magnetic material obtained in step (4) is placed in a vacuum coating machine, and then the SmCo alloy is placed in a crucible and then placed in the vacuum coating machine, and the SmCo alloy is evaporated on the surface of the magnet to obtain a coated NdFeB magnetic material, wherein the evaporation time is 45 min, and the absolute pressure in the evaporation conditions is 6*10 -3 Pa, the temperature is 600℃, and the film thickness is 3μm.

[0035] By adopting the above technical scheme, samarium cobalt alloy is deposited on the surface of neodymium iron boron by vacuum coating, so that a dense and evenly distributed coating is formed on the surface of neodymium iron boron magnetic material. At the same time, under vacuum conditions, oxygen atoms are not easily introduced into the coating, thereby reducing the combination of oxygen atoms and magnetic materials, thereby ensuring the excellent magnetic properties of the magnetic materials.

[0036] In summary, this application has the following beneficial effects:

[0037] 1. The NdFeB magnetic material of the present application is added with a high temperature resistant agent and an auxiliary material. The high temperature resistant agent and the auxiliary material cooperate with each other. The high temperature resistant agent has better high temperature resistance. At the same time, some materials in the high temperature resistant agent have better magnetic properties. In order to improve the coercive force of the NdFeB magnetic material while improving the high temperature resistance of the NdFeB magnetic material, the auxiliary agent is composed of yttrium samarium alloy and lanthanum nickel cobalt alloy to reduce the remanence temperature coefficient and coercive force temperature coefficient of the NdFeB magnetic material.

[0038] 2. An antioxidant is added to the NdFeB magnetic material of the present application, and the antioxidant is convenient for reducing the oxidation of rare earth elements during the preparation process of the NdFeB magnetic material, thereby improving the coercive force of the NdFeB magnetic material. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a flow chart of the method provided in the embodiment of the present application. DETAILED DESCRIPTION

[0040] The present application is further described in detail below with reference to the embodiments.

[0041] The shape of the NdFeB magnetic material of the present application includes but is not limited to a cylinder and a cuboid. Further preferably, the shape of the NdFeB magnetic material of the present application is a cylinder, and the diameter of the cylinder is 4-10 mm.

[0042] The gadolinium-iron alloy of the present application contains 71% gadolinium and 29% iron.

[0043] The praseodymium-neodymium alloy in the present application is praseodymium-neodymium powder (PN): purchased from Beijing Xingrongyuan Technology Co., Ltd., it is a mixture of praseodymium powder and neodymium powder, the purity of praseodymium powder and neodymium powder are both 99.99%, praseodymium accounts for 15.5wt% of the total amount of praseodymium-neodymium powder, and its particle size can be adjusted as needed. This embodiment specifically takes two particle sizes of 1-6um and 8-12μm as examples for explanation.

[0044] The ferroboron in the present application is ferroboron powder: purchased from Hebei Yirui Alloy Welding Material Co., Ltd., low carbon ferroboron powder (C≤0.1%), boron content is 20%, and its particle size can be adjusted as needed. This embodiment is also described by taking 1-6μm and 6-12m as two particle sizes.

[0045] The yttrium-samarium alloy of the present application includes 90% samarium and 10% yttrium.

[0046] The lanthanum nickel-cobalt alloy of the present application includes 61% nickel, 32% lanthanum, 6.8% cobalt, and 0.2% impurities.

[0047] The manganese-aluminum-carbon alloy of the present application includes 54% manganese, 44% aluminum, and 2% carbon.

[0048] The iridium-nickel alloy of the present application includes 40% iridium and 60% nickel.

[0049] Example

[0050] Example 1

[0051] The NdFeB magnetic material of this embodiment is composed of the following raw materials in weight percentage: 19% praseodymium-neodymium alloy, 1% gadolinium-iron alloy, 5% cerium, 0.5% ferroboron, 0.1% copper, 0.2% aluminum, 0.1% titanium, 0.1% cobalt, 0.1% antioxidant, 1% auxiliary material, 1% high temperature resistant agent, and the balance is iron. The auxiliary material is composed of yttrium-samarium alloy and lanthanum-nickel-cobalt alloy in a mass ratio of 1:1, and the high temperature resistant agent is composed of nano-silicon carbide and gallium in a mass ratio of 1:3. The antioxidant is composed of iridium-nickel alloy and triethanolamine borate in a mass ratio of 6:2. The high temperature resistant agent is acidified and degreased.

[0052] The preparation method of the NdFeB magnetic material of this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0053] (1) Preparation of base material: mixing praseodymium-neodymium alloy, gadolinium-iron alloy, cerium, ferroboron, copper, aluminum, titanium, cobalt, antioxidant, auxiliary material, high temperature resistant agent and iron, smelting to obtain molten liquid, casting the obtained molten liquid to spin a strip, and obtaining a strip-spinning sheet; wherein the smelting temperature is 1400° C.;

[0054] (2) crushing: the stripping pieces obtained in step (1) are subjected to hydrogen crushing to obtain hydrogen crushed powder; the particle size of the hydrogen crushed powder is 3 μm;

[0055] (3) Orientation and pressing; the hydrogen-crushed powder obtained in step (2) is pressed in a molding die, magnetized, and demagnetized to obtain a raw magnet; the density of the raw magnet is 4g / cm 3 ;

[0056] (4) Sintering: The green magnet obtained in step (3) is sintered at 1100°C for 4 hours. Nitrogen is filled during the sintering process. Before sintering, the green magnet is heated to 500°C and kept at this temperature for 1 hour. Then, the temperature is raised to 800°C and kept at this temperature for 30 minutes. After sintering, the green magnet is tempered at 800°C for 4 hours, cooled to 500°C, tempered for 1 hour, and then cooled to room temperature.

[0057] Embodiment 2-5

[0058] Examples 2-5 are NdFeB magnetic materials with different raw material components. The raw material component ratio of the NdFeB magnetic material of each example is shown in Table 1, and the unit of the raw material ratio is %.

[0059] Table 1 Ratio of raw materials of NdFeB magnetic materials of Examples 1-5

[0060]

[0061]

[0062] The difference between Example 2-5 and Example 1 is that the ratios of the raw material components are different, and the rest are exactly the same as Example 1.

[0063] The preparation method of the NdFeB magnetic material of Examples 2-5 is exactly the same as that of Example 1.

[0064] Example 6

[0065] The difference between this embodiment and Embodiment 5 is that the auxiliary material consists of yttrium-samarium alloy and lanthanum-nickel-cobalt alloy in a mass ratio of 5:5, and the high temperature resistant agent consists of nano-silicon carbide, gallium, and manganese-aluminum-carbon alloy in a mass ratio of 1:1:1, and the rest is exactly the same as Embodiment 5.

[0066] The preparation method of the NdFeB magnetic material in this embodiment is exactly the same as that in Embodiment 5.

[0067] Example 7

[0068] The difference between this embodiment and embodiment 6 is that the high temperature resistant agent is composed of nano silicon carbide, gallium, and manganese aluminum carbon alloy in a mass ratio of 3:3:1, and the rest is exactly the same as embodiment 6.

[0069] The preparation method of the NdFeB magnetic material in this embodiment is exactly the same as that in Example 6.

[0070] Example 8

[0071] The difference between this embodiment and embodiment 6 is that the high temperature resistant agent is composed of nano silicon carbide, gallium, and manganese aluminum carbon alloy in a mass ratio of 5:6:2, and the rest is exactly the same as embodiment 6.

[0072] The preparation method of the NdFeB magnetic material in this embodiment is exactly the same as that in Example 6.

[0073] Example 9

[0074] The difference between this embodiment and embodiment 8 is that the nano silicon carbide is pretreated silicon carbide, and the preparation method of the pretreated silicon carbide comprises the following steps: adding silicon carbide powder to 0.11g / mL NaOH solution, stirring at a constant temperature of 90°C for 4h, then washing to neutrality and drying to obtain silicon carbide powder 1; adding silane coupling agent KH550 to 300ml of toluene to obtain a mixed solution, and then adding 50g of silicon carbide powder 1 to the mixed solution, stirring at a constant temperature of 90°C for 4h, filtering after the reaction, and obtaining silicon carbide powder 2. Wash the silicon carbide powder 2 thoroughly with acetone, vacuum filter and dry to constant weight. The rest is exactly the same as embodiment 8.

[0075] The preparation method of the NdFeB magnetic material in this embodiment is exactly the same as that in Example 8.

[0076] Example 10

[0077] The difference between this embodiment and embodiment 9 is that the pretreated silicon carbide is modified nano pretreated silicon carbide, and the preparation method of the modified nano pretreated silicon carbide comprises the following steps: plating a layer of lanthanum-cerium alloy on the surface of the pretreated nano silicon carbide by vacuum plating, so that the silicon carbide has a core-shell structure. The rest is exactly the same as embodiment 8.

[0078] The preparation method of the NdFeB magnetic material in this embodiment is exactly the same as that in Example 8.

[0079] Embodiment 11

[0080] The NdFeB magnetic material of this embodiment is exactly the same as that of Embodiment 8.

[0081] The preparation method of the NdFeB magnetic material of this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0082] (1) Preparation of base material: mixing praseodymium-neodymium alloy, gadolinium-iron alloy, cerium, ferroboron, copper, aluminum, titanium, cobalt, antioxidant, auxiliary material, high temperature resistant agent and iron, smelting to obtain molten liquid, casting the obtained molten liquid to spin a strip, and obtaining a strip-spinning sheet; wherein the smelting temperature is 1400° C.;

[0083] (2) crushing: the stripping pieces obtained in step (1) are subjected to hydrogen crushing to obtain hydrogen crushed powder; the particle size of the hydrogen crushed powder is 3 μm;

[0084] (3) Orientation and pressing; the hydrogen-crushed powder obtained in step (2) is pressed in a molding die, magnetized, and demagnetized to obtain a raw magnet; the density of the raw magnet is 4g / cm 3 ;

[0085] (4) Sintering: the green magnet obtained in step (3) is sintered at 1100°C for 4 hours, and nitrogen is charged during the sintering process. Before sintering, the green magnet is heated to 500°C, kept at this temperature for 1 hour, and then heated to 800°C and kept at this temperature for 30 minutes. After sintering, the green magnet is tempered at 800°C for 4 hours, cooled to 500°C, tempered for 1 hour, and then cooled to room temperature to obtain the product;

[0086] (5) Preparation of corrosion-resistant layer: A corrosion-resistant layer is plated on the surface of the NdFeB magnetic material obtained in step (4), and the thickness of the corrosion-resistant layer is 160 nm.

[0087] Example 12

[0088] The NdFeB magnetic material of this embodiment is exactly the same as that of Embodiment 11.

[0089] The preparation method of the NdFeB magnetic material of this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0090] (1) Preparation of base material: mixing praseodymium-neodymium alloy, gadolinium-iron alloy, cerium, ferroboron, copper, aluminum, titanium, cobalt, antioxidant, auxiliary material, high temperature resistant agent and iron, smelting to obtain molten liquid, casting the obtained molten liquid to spin a strip, and obtaining a strip-spinning sheet; wherein the smelting temperature is 1400° C.;

[0091] (2) crushing: the stripping pieces obtained in step (1) are subjected to hydrogen crushing to obtain hydrogen crushed powder; the particle size of the hydrogen crushed powder is 3 μm;

[0092] (3) Orientation and pressing; the hydrogen-crushed powder obtained in step (2) is pressed in a molding die, magnetized, and demagnetized to obtain a raw magnet; the density of the raw magnet is 4g / cm 3 ;

[0093] (4) Sintering: the green magnet obtained in step (3) is sintered at 1100°C for 4 hours, and nitrogen is charged during the sintering process. Before sintering, the green magnet is heated to 500°C, kept at this temperature for 1 hour, and then heated to 800°C and kept at this temperature for 30 minutes. After sintering, the green magnet is tempered at 800°C for 4 hours, cooled to 500°C, tempered for 1 hour, and then cooled to room temperature to obtain the product;

[0094] (5) Preparation of coating layer: placing the NdFeB magnetic material obtained in step (4) into a vacuum coating machine, placing the samarium-cobalt alloy into a crucible and then placing it into the vacuum coating machine, and vapor-depositing the mixture on the surface of the magnet to obtain a coated NdFeB magnetic material;

[0095] (6) Preparation of corrosion-resistant layer: A corrosion-resistant layer is plated on the surface of the NdFeB magnetic material obtained in step (5), and the thickness of the corrosion-resistant layer is 180 nm.

[0096] Comparative Example

[0097] Comparative Example 1

[0098] The NdFeB magnetic material of this comparative example is composed of the following raw materials in weight percentage: 19% of praseodymium-neodymium alloy, 1% of gadolinium-iron alloy, 5% of cerium, 0.5% of ferroboron, 0.1% of copper, 0.2% of aluminum, 0.1% of titanium, 0.1% of cobalt, 0.1% of antioxidant, 1% of auxiliary material, and the balance is iron. The rest is exactly the same as in Example 1.

[0099] The preparation method of the NdFeB magnetic material of this comparative example is as follows: Figure 1 As shown, the following steps are included:

[0100] (1) Preparation of base material: mixing praseodymium-neodymium alloy, gadolinium-iron alloy, cerium, ferroboron, copper, aluminum, titanium, cobalt, antioxidant, auxiliary materials and iron, smelting to obtain molten liquid, casting the obtained molten liquid for strip spinning to obtain strip spinning sheets; wherein the smelting temperature is 1400° C.;

[0101] (2) crushing: the stripping pieces obtained in step (1) are subjected to hydrogen crushing to obtain hydrogen crushed powder; the particle size of the hydrogen crushed powder is 3 μm;

[0102] (3) Orientation and pressing; the hydrogen-crushed powder obtained in step (2) is pressed in a molding die, magnetized, and demagnetized to obtain a raw magnet; the density of the raw magnet is 4g / cm 3 ;

[0103] (4) Sintering: The green magnet obtained in step (3) is sintered at 1100°C for 4 hours. Nitrogen is filled during the sintering process. Before sintering, the green magnet is heated to 500°C and kept at this temperature for 1 hour. Then, the temperature is raised to 800°C and kept at this temperature for 30 minutes. After sintering, the green magnet is tempered at 800°C for 4 hours, cooled to 500°C, tempered for 1 hour, and then cooled to room temperature.

[0104] Comparative Example 2

[0105] The NdFeB magnetic material of this comparative example is composed of the following raw materials in weight percentage: 19% of praseodymium-neodymium alloy, 1% of gadolinium-iron alloy, 5% of cerium, 0.5% of ferroboron, 0.1% of copper, 0.2% of aluminum, 0.1% of titanium, 0.1% of cobalt, 0.1% of antioxidant, 1% of high temperature resistant agent, and the balance is iron. The rest is exactly the same as in Example 1.

[0106] The preparation method of the NdFeB magnetic material of this comparative example is as follows: Figure 1 As shown, the following steps are included:

[0107] (1) Preparation of base material: mixing praseodymium-neodymium alloy, gadolinium-iron alloy, cerium, ferroboron, copper, aluminum, titanium, cobalt, antioxidant, high temperature resistant agent and iron, smelting to obtain molten liquid, casting the obtained molten liquid for strip spinning to obtain strip spinning sheet; wherein the smelting temperature is 1400° C.;

[0108] (2) crushing: the stripping pieces obtained in step (1) are subjected to hydrogen crushing to obtain hydrogen crushed powder; the particle size of the hydrogen crushed powder is 3 μm;

[0109] (3) Orientation and pressing; the hydrogen-crushed powder obtained in step (2) is pressed in a molding die, magnetized, and demagnetized to obtain a raw magnet; the density of the raw magnet is 4g / cm 3 ;

[0110] (4) Sintering: The green magnet obtained in step (3) is sintered at 1100°C for 4 hours. Nitrogen is filled during the sintering process. Before sintering, the green magnet is heated to 500°C and kept at this temperature for 1 hour. Then, the temperature is raised to 800°C and kept at this temperature for 30 minutes. After sintering, the green magnet is tempered at 800°C for 4 hours, cooled to 500°C, tempered for 1 hour, and then cooled to room temperature.

[0111] Comparative Example 3

[0112] The difference between this comparative example and Example 1 is that the high temperature resistant agent is gallium, and the other aspects are completely different from Example 1.

[0113] The preparation method of the NdFeB magnetic material in this comparative example is exactly the same as that in Example 1.

[0114] Comparative Example 4

[0115] The difference between this comparative example and Example 1 is that the auxiliary material is lanthanum nickel cobalt alloy, and the rest is completely different from Example 1.

[0116] The preparation method of the NdFeB magnetic material in this comparative example is exactly the same as that in Example 1.

[0117] Detection Methods

[0118] Magnetic property test: The NdFeB magnetic materials prepared in Examples 1-12 and Comparative Examples 1-4 were tested for coercive force and Curie temperature according to the magnetic test method in GB / T3217 "Permanent Magnet (Hard Magnetic) Materials". The test results are shown in Table 2.

[0119] Maximum operating temperature test: The NdFeB magnetic materials prepared in Examples 1-12 and Comparative Examples 1-4 were tested for their maximum temperatures according to the test method in GB / T13560-2017 "Sintered NdFeB Permanent Magnet Materials". The test results are shown in Table 2.

[0120] Table 2 Magnetic properties test of NdFeB magnetic materials of Examples 1-12 and Comparative Examples 1-4

[0121]

[0122]

[0123] In combination with Example 1 and Comparative Examples 1-2, and in combination with Table 2, it can be seen that, relative to Comparative Examples 1 and 2, in Example 1, a high-temperature resistant agent and an auxiliary material are added to the magnetic material system, and the high-temperature resistant agent and the auxiliary material cooperate with each other, and the coercive force and Curie temperature of the prepared NdFeB magnetic material are significantly higher than those of Comparative Examples 1 and 2. The cooperation of the auxiliary material and the high-temperature resistant agent facilitates increasing the maximum operating temperature of the NdFeB magnetic material.

[0124] Combining Example 1 and Comparative Example 3, and combining with Table 2, it can be seen that compared with a single-component high-temperature resistant agent, after the high-temperature resistant agent in the raw material is compounded with multiple components, the NdFeB magnetic material obtained has higher coercive force and Curie temperature, and a higher maximum operating temperature, and better high-temperature resistance.

[0125] Combining Example 1 and Comparative Example 4, and combining with Table 2, it can be seen that compared with the auxiliary material having only a single component, the NdFeB magnetic material obtained after the auxiliary material in the raw material is compounded with yttrium-samarium alloy and lanthanum-nickel-cobalt alloy has better performance in all aspects, and the coercive force, Curie temperature and maximum operating temperature are all better.

[0126] In combination with Examples 1-5 and Table 2, it can be seen that the magnetic properties of the NdFeB magnetic material obtained by adjusting the ratio of the components of the NdFeB magnetic material will change accordingly. When there are too much or too little antioxidants, auxiliary materials, and high temperature resistant agents in the NdFeB magnetic material, the magnetic properties are not as good as the magnetic properties when the mass ratio of the antioxidants, auxiliary materials, and high temperature resistant agents is in the range of (0.2-0.4):(1.5-1.9):(1.2-1.4).

[0127] In combination with Examples 5-8 and Table 2, it can be seen that when the high temperature resistant agent is compounded with three components of nano-silicon carbide, gallium, and manganese aluminum carbon alloy, the magnetic properties of the obtained NdFeB magnetic material are better than the NdFeB magnetic material in which the high temperature resistant agent is compounded with two components, and the coercive force, Curie temperature and maximum operating temperature of the NdFeB magnetic material are better.

[0128] Combining Examples 8-10 and Table 2, it can be seen that the coercive force, Curie temperature and maximum operating temperature of the NdFeB magnetic material prepared by modifying the nano-silicon carbide are also better.

[0129] Combining Example 8 and Example 11 with Table 2, it can be seen that coating a corrosion-resistant layer on the surface of the NdFeB magnetic material can reduce the corrosion of the NdFeB magnetic material and help improve the magnetic properties of the NdFeB magnetic material.

[0130] Combining Example 8 and Example 12 with Table 2, it can be seen that by coating a layer of alloy film on the surface of NdFeB magnetic material, the coercive force, Curie temperature and maximum operating temperature of the obtained NdFeB magnetic material are significantly improved.

[0131] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A neodymium iron boron magnetic material, characterized in that: The invention comprises the following raw materials in weight percentage: 19-21% praseodymium-neodymium alloy, 1-2% gadolinium-iron alloy, 5-10% cerium, 0.5-1% ferroboron, 0.1-0.5% copper, 0.2-0.5% aluminum, 0.1-0.5% titanium, 0.1-0.5% cobalt, 0.1-0.5% antioxidant, 1-2% auxiliary material, 1-2% high temperature resistant agent, and the balance is iron. The auxiliary material is composed of yttrium-samarium alloy and lanthanum-nickel-cobalt alloy in a mass ratio of (3-5):(3-5), and the high temperature resistant agent is at least two of nano silicon carbide, gallium, and manganese-aluminum-carbon alloy. The high temperature resistant agent is composed of nano silicon carbide, gallium, and manganese aluminum carbon alloy in a mass ratio of (3-5):(3-6):(1-2); The nano silicon carbide is pretreated silicon carbide, and the preparation method of the pretreated silicon carbide comprises the following steps: adding silicon carbide micropowder to a NaOH solution, mixing, washing to neutrality and drying to obtain silicon carbide micropowder 1; adding a silane coupling agent to toluene to obtain a mixed solution, then adding silicon carbide micropowder 1 to the mixed solution, stirring for reaction, filtering, and obtaining silicon carbide micropowder 2; washing the silicon carbide micropowder 2 with acetone, vacuum filtering, and drying to constant weight to obtain the obtained product; The pretreated silicon carbide is modified nano pretreated silicon carbide. The preparation method of the modified nano pretreated silicon carbide comprises the following steps: plating a layer of lanthanum-cerium alloy on the surface of the pretreated nano silicon carbide by vacuum plating, so that the silicon carbide has a core-shell structure.

2. The NdFeB magnetic material according to claim 1, characterized in that: The mass ratio of the antioxidant, auxiliary material and high temperature resistant agent is (0.2-0.4):(1.5-1.9):(1.2-1.4).

3. The NdFeB magnetic material according to claim 1, characterized in that: The high temperature resistant agent is subjected to acidification and degreasing treatment.

4. The NdFeB magnetic material according to claim 1, characterized in that: The antioxidant is composed of iridium nickel alloy and triethanolamine borate in a mass ratio of (5-7):(1-2).

5. A method for preparing a NdFeB magnetic material according to any one of claims 1 to 4, characterized in that: The following steps are included: (1) Preparation of base material: the above raw materials are mixed and smelted to obtain a molten liquid, and the obtained molten liquid is cast to perform strip spinning to obtain a strip spinning sheet; (2) pulverizing: subjecting the stripped pieces obtained in step (1) to hydrogen pulverization to obtain hydrogen pulverized powder; (3) Orientation and pressing: the hydrogen-crushed powder obtained in step (2) is pressed in a molding die, magnetized, and demagnetized to obtain a raw magnet; (4) Sintering: The green magnet obtained in step (3) is sintered at 1100-1250°C, tempered and cooled to obtain a magnet.

6. The method for preparing a NdFeB magnetic material according to claim 5, characterized in that: The following steps are also included: (5) Preparation of corrosion-resistant layer: A corrosion-resistant layer is plated on the surface of the NdFeB magnetic material obtained in step (4), and the thickness of the corrosion-resistant layer is 150-180 nm.

7. The method for preparing a NdFeB magnetic material according to claim 5, characterized in that: The density of the green magnet obtained in step (3) is 3.8-4 g / cm 3 .

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