High-temperature-resistant neodymium iron boron magnetic material and preparation method thereof

Abstract

The invention belongs to the technical field of magnetic materials, and particularly relates to a high-temperature-resistant neodymium iron boron magnetic material and a preparation method thereof. The magnetic material comprises the following raw materials in parts by weight: 60-70 parts of a neodymium iron boron magnetic material, 10-15 parts of an alloy material, 3-5 parts of nano hafnium oxide, 2-4 parts of nano magnesium oxide, 1-3 parts of silicon carbide, 0.5-1 part of carbon nanotubes, 0.05-0.07 part of a silane coupling agent and 5-8 parts of a high-temperature-resistant silicon-containing copolymer. The alloy material comprises the following raw materials in percentage by mass: 20-30% of molybdenum, 10-20% of tungsten, 5-10% of tan, 1-5% of aluminum, 2-4% of niobium and the balance of iron. The neodymium iron boron magnetic material is good in high temperature resistance and good in comprehensive magnetic performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic materials, and particularly relates to a high-temperature resistant neodymium iron boron magnetic material and a preparation method thereof. Background Art

[0002] Neodymium iron boron permanent magnet materials are the most magnetic permanent magnets at present. They have excellent properties such as high magnetic energy product and high cost performance. The application of neodymium iron boron permanent magnet materials in the motor field is becoming more and more extensive. Since a large amount of heat is generated during the operation of the motor, it is required that the magnet has good temperature resistance to ensure the effective operation of the motor. This requires the magnet to have higher coercivity and high-temperature resistance to prevent the magnetic properties from dropping sharply due to temperature rise during use. However, the magnetic properties of general neodymium iron boron magnets have already dropped sharply when the working temperature rises to 120 °C, and they cannot even be used normally. However, the working temperature of motors used in fields such as new energy vehicles is usually as high as above 180 °C. Obviously, ordinary neodymium iron boron magnets cannot meet this high-temperature requirement. Summary of the Invention

[0003] The first object of the present invention is to provide a high-temperature resistant neodymium iron boron magnetic material, aiming to solve the technical problem of poor high-temperature resistance of existing neodymium iron boron magnetic materials.

[0004] The second object of the present invention is to provide a preparation method of a high-temperature resistant neodymium iron boron magnetic material, aiming to solve the technical problems that the preparation of existing neodymium iron boron magnetic materials is complex and it is difficult to obtain neodymium iron boron magnetic materials with good high-temperature resistance.

[0005] In order to achieve the above invention objects, the technical solutions adopted by the present invention are as follows: On the one hand, the present invention provides a high-temperature resistant neodymium iron boron magnetic material, which comprises the following raw materials in parts by weight: Neodymium iron boron magnetic material 60 - 70 parts Alloy material 10 - 15 parts Nano hafnium oxide 3 - 5 parts Nano magnesium oxide 2 - 4 parts Silicon carbide 1 - 3 parts Carbon nanotubes 0.5 - 1 part Silane coupling agent 0.05 - 0.07 part High-temperature resistant silicon-containing copolymer 5 - 8 parts; The alloy material comprises the following raw materials in mass percentage: 20 - 30% molybdenum, 10 - 20% tungsten, 5 - 10% tantalum, 1 - 5% aluminum, 2 - 4% niobium, and the balance is iron.

[0006] Among them, the neodymium iron boron magnetic material is Nd 2 Fe 14 B magnetic powder.

[0007] Among them, the particle size of the hafnium oxide nanometer is 50 - 80 nm.

[0008] Among them, the particle size of the magnesium oxide nanometer is 50 - 100 nm.

[0009] Among them, the particle size of the silicon carbide is 200 - 300 nm.

[0010] Among them, the silane coupling agent is at least one of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidyletheroxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0011] On the other hand, the present invention provides a method for preparing a high-temperature resistant neodymium iron boron magnetic material, including the following preparation steps: Step 1: Mix the neodymium iron boron magnetic material and the alloy material, and then place them in an intermediate frequency vacuum induction melting furnace for melting. After melting into a uniform solution, it is cast into a cast sheet for later use. Step 2: Crush the cast sheet in a hydrogen crushing furnace, and then make it into powder in a jet mill. Step 3: Mix and grind the above powder with hafnium oxide nanometer, magnesium oxide nanometer, silicon carbide, carbon nanotube, silane coupling agent, and high-temperature resistant silicon-containing copolymer evenly to obtain a mixed powder. Step 4: Under the protection of inert gas, place the mixed powder in a magnetic field for orientation and shaping, then perform static pressure forming, and finally cure to obtain the high-temperature resistant neodymium iron boron magnetic material.

[0012] Among them, in Step 1, the melting temperature is 1000 - 1200 °C.

[0013] Among them, in Step 2, the particle size of the powder obtained after hydrogen crushing in the hydrogen crushing furnace is 60 - 80 μm, and the particle size of the powder after jet mill treatment is 2 - 3 μm. In Step 3, in the mixed powder, the tube diameter of the carbon nanotube is 10 - 20 nm, the length of the carbon nanotube is 20 - 30 μm, and the particle size of the remaining raw materials is 50 - 80 nm.

[0014] Among them, in Step 4, the magnetic field strength is 1 - 3 T, the static pressure forming pressure is 400 - 500 MPa, and the curing temperature is 80 - 100 °C.

[0015] The beneficial effects of the present invention: The high-temperature resistant neodymium iron boron magnetic material of the present invention, by adding specific types of alloy materials, hafnium oxide nanometer, magnesium oxide nanometer, silicon carbide, carbon nanotube, silane coupling agent, and high-temperature resistant silicon-containing copolymer in the neodymium iron boron magnetic material matrix, and strictly controlling the addition amount of each component, the components cooperate with each other and act together, so that the obtained high-temperature resistant neodymium iron boron magnetic material has good high-temperature resistance and excellent comprehensive magnetic properties.

[0016] In the present invention, by adding carbon nanotubes with a high aspect ratio and a high-temperature-resistant silicon-containing copolymer, and with the interaction between the two, the carbon nanotubes are interspersed in the network-shaped high-temperature-resistant silicon-containing copolymer, making the overall structure of the magnetic material more stable. Cooperating with other components and acting together, it effectively improves the high-temperature resistance, comprehensive magnetic properties, and mechanical properties of the material. Detailed implementation manners

[0017] To make the objectives, technical solutions, and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. The embodiments described below are some, but not all, of the embodiments of the present invention. Combining the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer; for the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0018] In the description of the present invention, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, or B exists alone. Where A and B may be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0019] In the description of the present invention, "at least one" means one or more, and "a plurality" means two or more. "At least one (item)" or a similar expression thereof refers to any combination of these items, including any combination of single item (item) or plural items (items). For example, "at least one (item) of a, b, or c", or "at least one (item) of a, b, and c" can both represent: a, b, c, a-b (that is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple respectively.

[0020] It should be understood that the weights of the relevant components mentioned in the embodiments of the present invention not only can refer to the specific contents of each component, but also can represent the proportional relationship of the weights between each component. Therefore, as long as the contents of the relevant components in the embodiments of the present invention are scaled up or down in proportion, they are within the scope disclosed in the present invention. Specifically, the weights described in the embodiments of the present invention can be mass units well-known in the chemical engineering field such as μg, mg, g, kg, etc.

[0021] In addition, unless otherwise explicitly stated in the context, the singular form of a word shall be construed to include its plural form. The terms "comprising" or "having" are intended to specify the presence of features, quantities, steps, operations, elements, parts, or combinations thereof, but are not used to preclude the presence or possible addition of one or more other features, quantities, steps, operations, elements, parts, or combinations thereof.

[0022] An embodiment of the present invention provides a high-temperature resistant neodymium iron boron magnetic material, which comprises the following raw materials in parts by weight: 60 - 70 parts of neodymium iron boron magnetic material 10 - 15 parts of alloy material 3 - 5 parts of hafnium oxide nanoparticles 2 - 4 parts of magnesium oxide nanoparticles 1 - 3 parts of silicon carbide 0.5 - 1 part of carbon nanotubes 0.05 - 0.07 part of silane coupling agent 5 - 8 parts of high-temperature resistant silicon-containing copolymer; The alloy material comprises the following raw materials in mass percentages: 20 - 30% molybdenum, 10 - 20% tungsten, 5 - 10% tantalum, 1 - 5% aluminum, 2 - 4% niobium, and the balance is iron.

[0023] The high-temperature resistant neodymium iron boron magnetic material of the present invention, by adding specific types of alloy materials, hafnium oxide nanoparticles, magnesium oxide nanoparticles, silicon carbide, carbon nanotubes, silane coupling agent and high-temperature resistant silicon-containing copolymer into the neodymium iron boron magnetic material matrix, and strictly controlling the addition amounts of each component, the components cooperate with each other and act together, so that the prepared high-temperature resistant neodymium iron boron magnetic material has good high-temperature resistance and excellent comprehensive magnetic properties.

[0024] The present invention adds carbon nanotubes with a high aspect ratio and a high-temperature resistant silicon-containing copolymer. The two interact with each other, and the carbon nanotubes are interspersed in the network-like high-temperature resistant silicon-containing copolymer, making the overall structure of the magnetic material more stable. Cooperating with other components and acting together, it effectively improves the high-temperature resistance, comprehensive magnetic properties and mechanical properties of the material.

[0025] Among them, the neodymium iron boron magnetic material is Nd 2 Fe 14 B magnetic powder.

[0026] Among them, the particle size of the hafnium oxide nanoparticles is 50 - 80 nm.

[0027] Among them, the particle size of the magnesium oxide nanoparticles is 50 - 100 nm.

[0028] Among them, the particle size of the silicon carbide is 200 - 300 nm.

[0029] Among them, the silane coupling agent is at least one of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidyletheroxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0030] Among them, the preparation method of the high-temperature resistant silicon-containing copolymer is as follows: Mix methyldiphenylethynylsilane and bis(N-m-ethynylphenylphthalimide)ether in a ratio of 1:(0.2-1), carry out a curing reaction at 190°C for 2 hours and at 200°C for 4 hours, then increase the temperature at a rate of 20°C per hour to 300°C to complete the addition reaction, and continue to increase the temperature at this rate to 360°C to complete the Diels-Alder reaction to obtain a high-temperature resistant silicon-containing copolymer.

[0031] On the other hand, the present invention provides a preparation method of a high-temperature resistant neodymium iron boron magnetic material, including the following preparation steps: Step 1: Mix the neodymium iron boron magnetic material and the alloy material and place them in an intermediate frequency vacuum induction melting furnace for melting. After melting into a uniform solution, cast it into a cast sheet for later use; Step 2: Crush the cast sheet in a hydrogen crushing furnace, and then make it into powder in a jet mill; Step 3: Mix and grind the above powder with hafnium oxide nanoparticles, magnesium oxide nanoparticles, silicon carbide, carbon nanotubes, silane coupling agent, and high-temperature resistant silicon-containing copolymer evenly to obtain a mixed powder; Step 4: Under the protection of an inert gas, place the mixed powder in a magnetic field for orientation and shaping, then perform static pressure forming, and finally cure to obtain a high-temperature resistant neodymium iron boron magnetic material.

[0032] The preparation method of the present invention is simple, and the prepared neodymium iron boron magnetic material has good high-temperature resistance and comprehensive magnetic properties.

[0033] Among them, Step 1 is carried out under the protection of nitrogen.

[0034] Among them, in Step 1, the melting temperature is 1000-1200°C.

[0035] Among them, in Step 2, the powder obtained after hydrogen crushing has a particle size of 60-80μm, and the particle size of the powder after jet mill treatment is 2-3μm; in Step 3, in the mixed powder, the carbon nanotubes have a tube diameter of 10-20nm and a length of 20-30μm, and the particle sizes of the other raw materials are 50-80nm.

[0036] Specifically, in Step 3, first mix the carbon nanotubes and the silane coupling agent and grind them at a frequency of 50-60Hz for 20-30min, and then add the powder obtained in Step 2, hafnium oxide nanoparticles, magnesium oxide nanoparticles, silicon carbide, and high-temperature resistant silicon-containing copolymer and mix and grind them evenly at a frequency of 70-80Hz.

[0037] Among them, in step four, the magnetic field strength is 1 - 3 T, the static pressure forming pressure is 400 - 500 MPa, and the curing temperature is 80 - 100 °C.

[0038] To enable those skilled in the art to clearly understand the above implementation details and operations of the present invention, and to significantly reflect the advanced performance of the embodiments of the present invention, the following technical solutions will be illustrated by multiple embodiments.

[0039] Example 1 A high-temperature resistant neodymium iron boron magnetic material, which comprises the following raw materials in parts by weight: Neodymium iron boron magnetic material 65 parts Alloy material 12.5 parts Nano hafnium oxide 4 parts Nano magnesium oxide 3 parts Silicon carbide 2 parts Carbon nanotubes 0.75 parts Silane coupling agent 0.06 parts High-temperature resistant silicon-containing copolymer 6.5 parts; The alloy material comprises the following raw materials in mass percentages: 25% molybdenum, 15% tungsten, 7.5% tantalum, 3% aluminum, 3% niobium, and the balance is iron.

[0040] Among them, the neodymium iron boron magnetic material is Nd 2 Fe 14 B magnetic powder.

[0041] Among them, the particle size of the nano hafnium oxide is 65 nm.

[0042] Among them, the particle size of the nano magnesium oxide is 75 nm.

[0043] Among them, the particle size of the silicon carbide is 250 nm.

[0044] Among them, the silane coupling agent is β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0045] Among them, the preparation method of the high-temperature resistant silicon-containing copolymer is as follows: Mix methyl diphenylacetylenylsilane and bis(N-m-ethynylphenylphthalimide) ether in a ratio of 1:1, carry out a curing reaction at 190 °C for 2 hours and at 200 °C for 4 hours, then increase the temperature at a rate of 20 °C per hour to 300 °C to complete the addition reaction, and continue to increase the temperature at this rate to 360 °C to complete the Diels - Alder reaction to obtain the high-temperature resistant silicon-containing copolymer.

[0046] The preparation method of the above high-temperature resistant neodymium iron boron magnetic material comprises the following preparation steps: Step 1: By weight, mix 65 parts of neodymium-iron-boron magnetic material and 12.5 parts of alloy material, place them in an intermediate frequency vacuum induction melting furnace, and under nitrogen protection, melt at 1100 °C. After melting into a uniform solution, cast it into cast sheets for later use; Step 2: Crush the cast sheets in a hydrogen crushing furnace to obtain powders with a particle size of 70 μm, and then make them into powders with a particle size of 2.5 μm in a jet mill; Step 3: By weight, mix 0.75 parts of carbon nanotubes and 0.06 parts of silane coupling agent and grind them at a frequency of 55 Hz for 25 min. Then add the powder from Step 2, as well as 4 parts of hafnium oxide nanoparticles, 3 parts of magnesium oxide nanoparticles, 2 parts of silicon carbide, and 6.5 parts of high-temperature resistant silicon-containing copolymer for mixing, and grind evenly at a frequency of 75 Hz to obtain mixed powders. In the mixed powders, the carbon nanotubes have a diameter of 10 - 20 nm and a length of 20 - 30 μm, and the other raw materials have a particle size of 50 - 80 nm; Step 4: Under the protection of nitrogen inert gas, place the mixed powder in a magnetic field with a strength of 2 T for orientation and shaping, then press and form it under a pressure of 450 Mpa, and finally cure it at a temperature of 90 °C to obtain a high-temperature resistant neodymium-iron-boron magnetic material.

[0047] Example 2 A high-temperature resistant neodymium-iron-boron magnetic material, which comprises the following raw materials in parts by weight: Neodymium-iron-boron magnetic material 60 parts Alloy material 10 parts Hafnium oxide nanoparticles 3 parts Magnesium oxide nanoparticles 2 parts Silicon carbide 1 part Carbon nanotubes 0.5 part Silane coupling agent 0.05 part High-temperature resistant silicon-containing copolymer 5 parts; The alloy material comprises the following raw materials in mass percentages: 20% molybdenum, 10% tungsten, 5% tantalum, 1% aluminum, 2% niobium, and the balance is iron.

[0048] Among them, the neodymium-iron-boron magnetic material is Nd 2 Fe 14 B magnetic powder.

[0049] Among them, the hafnium oxide nanoparticles have a particle size of 50 nm.

[0050] Among them, the magnesium oxide nanoparticles have a particle size of 50 nm.

[0051] Among them, the silicon carbide has a particle size of 200 nm.

[0052] Among them, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0053] Among them, the preparation method of the high-temperature resistant silicon-containing copolymer is as follows: Mix methyldiphenylacetylenylsilane and bis(N-m-ethynylphenylphthalimide) ether in a ratio of 1:0.6, cure at 190 °C for 2 hours and 200 °C for 4 hours, then increase the temperature at a rate of 20 °C per hour to 300 °C to complete the addition reaction, and continue to increase the temperature at this rate to 360 °C to complete the Diels-Alder reaction to obtain the high-temperature resistant silicon-containing copolymer.

[0054] The preparation method of the above high-temperature resistant NdFeB magnetic material includes the following preparation steps: Step 1: Weigh 60 parts of NdFeB magnetic material and 10 parts of alloy material, mix them and place them in an intermediate frequency vacuum induction melting furnace. Under nitrogen protection, melt at 1000 °C, and pour the melted and uniform solution into a cast sheet for later use; Step 2: Crush the cast sheet in a hydrogenation crusher to obtain powder with a particle size of 60 μm, and then make it into powder with a particle size of 2 μm in a jet mill; Step 3: Weigh 0.5 part of carbon nanotubes and 0.05 part of silane coupling agent, mix them and grind for 20 min at a frequency of 50 Hz, then add the powder from Step 2, as well as 3 parts of hafnium oxide nanoparticles, 2 parts of magnesium oxide nanoparticles, 1 part of silicon carbide, and 5 parts of high-temperature resistant silicon-containing copolymer, and mix them by grinding at a frequency of 70 Hz to obtain a mixed powder. In the mixed powder, the carbon nanotubes have a diameter of 10 - 20 nm and a length of 20 - 30 μm, and the other raw materials have a particle size of 50 - 80 nm; Step 4: Under the protection of nitrogen inert gas, place the mixed powder in a magnetic field with a strength of 1 T for orientation and shaping, then press and form it under a pressure of 400 Mpa, and finally cure it at a temperature of 80 °C to obtain the high-temperature resistant NdFeB magnetic material.

[0055] Example 3 A high-temperature resistant NdFeB magnetic material, which comprises the following raw materials in parts by weight: NdFeB magnetic material 70 parts Alloy material 15 parts Hafnium oxide nanoparticles 5 parts Magnesium oxide nanoparticles 4 parts Silicon carbide 3 parts Carbon nanotubes 1 part Silane coupling agent 0.07 part High-temperature resistant silicon-containing copolymer 8 parts; The alloy material comprises raw materials in the following mass percentages: 30% molybdenum, 20% tungsten, 10% tantalum, 5% aluminum, 4% niobium, and the balance is iron.

[0056] Among them, the neodymium iron boron magnetic material is Nd 2 Fe 14 B magnetic powder.

[0057] Among them, the particle size of the nano hafnium oxide is 80 nm.

[0058] Among them, the particle size of the nano magnesium oxide is 100 nm.

[0059] Among them, the particle size of the silicon carbide is 300 nm.

[0060] Among them, the silane coupling agent is γ-glycidoxypropyltrimethoxysilane.

[0061] Among them, the preparation method of the high-temperature resistant silicon-containing copolymer is as follows: Mix methyl diphenyl ethynyl silane and bis(N-m-ethynylphenyl phthalimide) ether in a ratio of 1:0.2, cure at 190 °C for 2 hours and 200 °C for 4 hours, then complete the addition reaction at a heating rate of 20 °C per hour to 300 °C, and continue to heat at this rate to 360 °C to complete the Diels-Alder reaction to obtain the high-temperature resistant silicon-containing copolymer.

[0062] The preparation method of the above high-temperature resistant neodymium iron boron magnetic material includes the following preparation steps: Step 1: By weight, mix 70 parts of neodymium iron boron magnetic material and 15 parts of alloy material, place them in an intermediate frequency vacuum induction melting furnace, and melt at 1200 °C under nitrogen protection. After melting into a uniform solution, pour it into a cast sheet for later use; Step 2: Crush the cast sheet in a hydrogen crushing furnace to obtain a powder with a particle size of 80 μm, and then make it into a powder with a particle size of 3 μm in a jet mill; Step 3: By weight, mix 1 part of carbon nanotubes and 0.07 part of silane coupling agent and grind them at a frequency of 60 Hz for 30 min, then add the powder from Step 2, as well as 5 parts of nano hafnium oxide, 4 parts of nano magnesium oxide, 3 parts of silicon carbide, and 8 parts of high-temperature resistant silicon-containing copolymer for mixing, and grind evenly at a frequency of 80 Hz to obtain a mixed powder. In the mixed powder, the diameter of the carbon nanotubes is 10 - 20 nm, the length of the carbon nanotubes is 20 - 30 μm, and the particle size of the other raw materials is 50 - 80 nm; Step 4: Place the mixed powder under the protection of nitrogen inert gas, orient and shape it in a magnetic field with a strength of 3 T, then statically press it at a pressure of 500 Mpa, and finally cure it at a temperature of 100 °C to obtain the high-temperature resistant neodymium iron boron magnetic material.

[0063] Comparative Example 1 A neodymium iron boron magnetic material. The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not add a high-temperature resistant silicon-containing copolymer, and the other components and preparation method of Comparative Example 1 are the same as those of Example 1, which will not be elaborated here.

[0064] Comparative Example 2 A neodymium iron boron magnetic material. The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 does not add carbon nanotubes and silicon carbide, and the other components and preparation method of Comparative Example 2 are the same as those of Example 1, which will not be elaborated here.

[0065] Performance Test The neodymium iron boron magnetic materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to relevant performance tests, and the test results are shown in Table 1. The test methods are as follows: Detect its comprehensive magnetic properties according to the magnetic test method for permanent magnet (hard magnetic) materials of GB / T3217-2013; High-temperature resistance test: The neodymium iron boron magnetic materials prepared in Examples 1-3 and Comparative Examples 1-2 were processed into square samples with a specification of 30×16×3 mm by wire cutting for high-temperature resistance performance test. After this block was saturated with magnetization, the magnetic flux before aging was measured at room temperature. Then the sample was placed on a 1 mm iron sheet and placed in an oven at 150 °C for 1 h. After cooling to room temperature, the magnetic flux after aging was measured, and then the high-temperature irreversible loss was calculated. The high-temperature irreversible loss = (magnetic flux before aging - magnetic flux after aging) / magnetic flux before aging × 100%.

[0066] Table 1 Test Results Sample Residual Magnetism (mT) Intrinsic Coercivity (KA / m) Maximum Energy Product (KJ / m3) High Temperature Irreversible Loss (%) Example 1 961 890 162 0.07 Example 2 953 876 150 0.09 Example 3 957 871 154 0.1 Comparative Example 1 767 699 99 1.5 Comparative Example 2 731 667 104 1.3 As can be seen from Table 1, compared with the comparative examples, the high-temperature resistant neodymium iron boron magnetic material prepared in the examples of the present invention has more excellent comprehensive magnetic properties and better high-temperature resistance performance. The addition of the high-temperature resistant silicon-containing copolymer, carbon nanotubes, and silicon carbide of the present invention, and their compounding with other reagents of the present invention, while strictly controlling the addition amount of each substance, can effectively improve the magnetic properties and high-temperature resistance performance of the neodymium iron boron magnetic material.

[0067] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A high temperature resistant NdFeB magnetic material, characterized in that: The invention comprises the following raw materials in parts by weight: 60-70 parts of NdFeB magnetic material Alloy material 10-15 parts 3-5 parts of nano hafnium oxide 2-4 parts of nano magnesium oxide Silicon carbide 1-3 parts 0.5-1 part of carbon nanotubes Silane coupling agent 0.05-0.07 parts 5-8 parts of high temperature resistant silicon-containing copolymer; The alloy material includes the following raw materials in percentage by mass: 20-30% molybdenum, 10-20% tungsten, 5-10% tantalum, 1-5% aluminum, 2-4% niobium, and the balance is iron.

2. A high temperature resistant NdFeB magnetic material according to claim 1, characterized in that: The NdFeB magnetic material is Nd2Fe 14 B Magnetic powder.

3. The high temperature resistant NdFeB magnetic material according to claim 1, characterized in that: The particle size of the nano hafnium oxide is 50-80nm.

4. The high temperature resistant NdFeB magnetic material according to claim 1, characterized in that: The particle size of the nano magnesium oxide is 50-100nm.

5. The high temperature resistant NdFeB magnetic material according to claim 1, characterized in that: The particle size of the silicon carbide is 200-300nm.

6. The high temperature resistant NdFeB magnetic material according to claim 1, characterized in that: The silane coupling agent is at least one of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane and vinyltrimethoxysilane.

7. A method for preparing a high temperature resistant NdFeB magnetic material according to any one of claims 1 to 6, characterized in that: The method comprises the following preparation steps: Step 1: Mix the NdFeB magnetic material and the alloy material and place them in a medium frequency vacuum induction melting furnace for melting. After melting into a uniform solution, cast them into casting sheets for standby use; Step 2: crush the cast sheet in a hydrogen crushing furnace and then make it into powder in a jet mill; Step 3, mixing the above powder with nano hafnium oxide, nano magnesium oxide, silicon carbide, carbon nanotubes, silane coupling agent and high temperature resistant silicon-containing copolymer and grinding them evenly to obtain mixed powder; Step 4: Place the mixed powder in a magnetic field under the protection of inert gas for orientation and shaping, then subject it to static pressing and finally solidification to obtain a high temperature resistant NdFeB magnetic material.

8. The method for preparing a high temperature resistant NdFeB magnetic material according to claim 7, characterized in that: In step 1, the smelting temperature is 1000-1200°C.

9. The method for preparing a high temperature resistant NdFeB magnetic material according to claim 7, characterized in that: In step 2, the powder with a particle size of 60-80 μm is obtained after crushing in a hydrogen crushing furnace, and the powder particle size after air flow milling is 2-3 μm. In step 3, in the mixed powder, the diameter of the carbon nanotubes is 10-20 nm, the length of the carbon nanotubes is 20-30 μm, and the particle size of the remaining raw materials is 50-80 nm.

10. The method for preparing a high temperature resistant NdFeB magnetic material according to claim 7, characterized in that: In step 4, the magnetic field strength is 1-3T, the static pressure molding pressure is 400-500MPa, and the curing temperature is 80-100°C.