Magnetic powder modifier, preparation method and application thereof, and production method of neodymium-iron-boron magnet

Abstract

The invention discloses a magnetic powder modifier, a preparation method and application thereof and a production method of a neodymium-iron-boron magnet. The magnetic powder modifier comprises a first modification component and a second modification component, the first modified component comprises 20 to 70 parts by weight of a first ethylene compound, 25 to 60 parts by weight of a second ethylene compound, 1 to 45 parts by weight of a polyol ester compound and 0.01 to 0.5 part by weight of MoS2; and the second modified component comprises 0.5-2 parts by volume of a first ester compound and 0.5-2 parts by volume of a second ester compound. The magnetic powder modifier can effectively improve the magnetic performance of the neodymium-iron-boron magnet.

Description

Technical Field

[0001] The invention relates to a magnetic powder modifier and a preparation method and application thereof, and a production method of a neodymium iron boron magnet. Background Art

[0002] Rare earth permanent magnet materials can be widely used in wind power generation, energy-saving elevators, variable frequency air conditioners, new energy vehicles, intelligent robots and other fields. NdFeB magnets are tetragonal crystals formed by neodymium, iron and boron. Their magnetic energy product is greater than that of samarium cobalt magnets and they have higher magnetic properties. High-quality magnetic powder is the cornerstone for the preparation of high-performance NdFeB magnets. The particle size, distribution and fluidity of NdFeB magnetic powder have an important influence on the performance of sintered NdFeB magnets.

[0003] CN108417373A discloses a method for regulating the magnetic properties of sintered NdFeB, wherein the quick-setting sheet is subjected to hydrogen cracking treatment, the coarse powder after hydrogen cracking is screened into the barrel, and an organic antioxidant is added into the barrel at the same time, and the organic antioxidant enters the barrel through a pulse electromagnetic valve; the coarse powder with the organic antioxidant is stirred, the stirred coarse powder is subjected to air flow milling, the fine powder is screened, and the organic antioxidant is added and stirred at the same time; the stirred fine powder is subjected to pressing, sintering, and aging tempering treatment. The antioxidant is selected from one or a mixture of ethylene glycol diethyl ester, zinc stearate, and polyethylene glycol octane. The modification performance of the above antioxidant for magnetic powder needs to be strengthened.

[0004] CN108133818A discloses a method for anti-oxidation treatment of sintered NdFeB, wherein the NdFeB raw material is crushed into coarse powder, and the coarse powder is mixed with a first antioxidant for airflow milling. During the airflow milling process, a second antioxidant is injected into the airflow mill in the form of a spray. The first antioxidant includes benzotriazole, petroleum ether, thymol, and triphenylmethanol. The second antioxidant includes polyethylene oxide alkyl ether, an antistatic agent, ethanol, and 1-hexadecanol. The above antioxidants have limited improvement on the magnetic properties of the magnet. Summary of the invention

[0005] One object of the present invention is to provide a magnetic powder modifier, which can improve the magnetic properties of neodymium iron boron magnets. Another object of the present invention is to provide a method for preparing the magnetic powder modifier. Another object of the present invention is to provide a use of the magnetic powder modifier. Another object of the present invention is to provide a method for producing neodymium iron boron magnets, which can improve the magnetic properties of neodymium iron boron magnets.

[0006] In one aspect, the present invention provides a magnetic powder modifier, comprising a first modifying component and a second modifying component;

[0007] The first modified component comprises 20 to 70 parts by weight of a first ethylene compound represented by formula (I), 25 to 60 parts by weight of a second ethylene compound represented by formula (II), 1 to 45 parts by weight of a polyol ester compound represented by formula (III) and 0.01 to 0.5 parts by weight of MoS2;

[0008]

[0009] R1 and R2 are independently selected from C10 to C23 alkenyl, Among them, R a An alkyl group selected from C5 to C12, R b An alkylene group selected from C5 to C12;

[0010]

[0011] R3 and R4 are independently selected from C8-C15 alkyl groups;

[0012]

[0013] R5, R6, R7 and R8 are independently selected from C1-C3 alkylene groups, R9, R 10 , R 11 and R 12 Each independently selected from a C11 to C23 alkyl group;

[0014] The second modified component includes 0.5 to 2 parts by volume of a first ester compound and 0.5 to 2 parts by volume of a second ester compound;

[0015] The first ester compound is selected from one or more of methyl oleate, ethyl oleate, propyl oleate, isopropyl oleate, octyl oleate, isooctyl oleate, methyl palmitate, ethyl palmitate, propyl palmitate, isopropyl palmitate, octyl palmitate, isooctyl palmitate, polyethylene glycol dioleate, methyl myristate, ethyl myristate, propyl myristate, isopropyl myristate, octyl myristate, isooctyl myristate, methyl laurate, ethyl laurate, and propyl laurate;

[0016] The second ester compound is selected from one or more of trimethyl borate, triethyl borate, tripropyl borate, triisopropyl borate, tributyl borate, triisobutyl borate, tri-tert-butyl borate, tri-sec-butyl borate, and triethanolamine borate.

[0017] According to the magnetic powder modifier of the present invention, preferably, R1 and R2 are independently selected from C10-C23 alkenyl groups containing 1-3 unsaturated double bonds, R3 and R4 are independently selected from C10-C13 alkyl groups, R5-R8 are independently selected from C1-C2 alkylene groups, R9-R 12Each is independently selected from a C13 to C20 alkyl group.

[0018] According to the magnetic powder modifier of the present invention, preferably, the first ester compound is selected from one or more of ethyl oleate, isooctyl oleate, methyl palmitate, and methyl laurate; the second ester compound is selected from one or more of triethyl borate, triisopropyl borate, and tributyl borate.

[0019] On the other hand, the present invention provides a method for preparing a magnetic powder modifier, comprising the following steps:

[0020] (I) mixing a first ethylene compound, a second ethylene compound, a polyol ester compound and MoS2 to obtain a first modified component;

[0021] (II) The first ester compound and the second ester compound are mixed to obtain a second modified component.

[0022] In another aspect, the present invention provides a use of a magnetic powder modifier in improving the magnetic properties of NdFeB magnets, wherein the magnetic properties are selected from one or more of remanence, coercive force, maximum magnetic energy product, and squareness.

[0023] In another aspect, the present invention provides a method for producing a neodymium iron boron magnet, comprising the following steps:

[0024] (1) jet milling the mixed crude alloy powder and the first modified component in the magnetic powder modifier to obtain fine alloy powder; wherein the amount of the first modified component is 0.2 to 0.9‰ of the mass of the crude alloy powder;

[0025] (2) mixing fine alloy powder and the second modified component in the magnetic powder modifier to obtain modified magnetic powder; wherein the amount of the second modified component is 0.2 to 0.9‰ of the mass of the fine alloy powder;

[0026] (3) The modified magnetic powder is formed and then heat treated to obtain a NdFeB magnet.

[0027] According to the production method of the present invention, preferably, the air flow mill is carried out in the presence of an inert gas and oxygen, the inert gas pressure is 0.2-0.7 MPa, the oxygen content is 5-25 ppm, and the classifying wheel speed is 3500-6000 rpm.

[0028] According to the production method of the present invention, preferably, the modified magnetic powder is oriented and molded in a magnetic field with an intensity of 1 to 2.5 T to obtain a green body; the molding pressure is 2 to 16 MPa, and the holding time is 0.5 to 10 s;

[0029] Wherein, the orientation molding is not followed by isostatic pressing.

[0030] According to the production method of the present invention, preferably, the heat treatment comprises the following steps:

[0031] The formed green body is sequentially sintered at 320-400° C. for 35-75 min, 410-570° C. for 45-85 min, and 950-1250° C. for 2.5-7.5 h to obtain a sintered body;

[0032] The sintered body is subjected to aging treatment at 700-1050° C. for 0.5-6 h and at 460-650° C. for 1-7 h to obtain a NdFeB magnet.

[0033] According to the production method of the present invention, preferably, the average specific surface diameter of the fine alloy powder is 2 to 4.2 μm, and the D 90 / D 10 The repose angle of fine alloy powder is ≤50°, and the bulk density of fine alloy powder is 1.6-3.5g / cm 3 The tap density of fine alloy powder is 2-5 g / cm 3 ;

[0034] The content of nitrogen in the NdFeB magnet is 285-760 ppm.

[0035] The magnetic powder modifier of the present invention has a good effect on improving the fluidity and oxidation resistance of NdFeB magnetic powder, and improves the magnetic properties of NdFeB magnets. The fine powder modifier of the present invention can simplify the production process of NdFeB magnets, and high-density compacts can be obtained without an isostatic pressing process. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited thereto.

[0037] <Magnetic Powder Modifier>

[0038] The magnetic powder modifier of the present invention comprises a first modifying component and a second modifying component. In certain embodiments, the magnetic powder modifier is composed of the first modifying component and the second modifying component. The first modifying component and the second modifying component are two separate components and are not mixed. The first modifying component and the second modifying component are introduced separately below.

[0039] The first modifying component

[0040] The first modified component of the present invention comprises a first ethylene compound, a second ethylene compound, a polyol ester compound and MoS2. Preferably, the first modified component consists of a first ethylene compound, a second ethylene compound, a polyol ester compound and MoS2.

[0041] The first ethylene compound is represented by formula (I):

[0042]

[0043] R1 and R2 are independently selected from C10 to C23 alkenyl, R a An alkyl group selected from C5 to C12, R b Preferably, R1 and R2 are independently selected from C10 to C23 alkenyl groups.

[0044] Preferably, R a An alkyl group selected from C5 to C12, R b is selected from C5 to C12 alkylene groups. More preferably, R a An alkyl group selected from C7 to C9, R b An alkylene group selected from C8 to C10. Examples of alkyl groups include, but are not limited to, hexyl, heptyl, octyl, nonyl, decanyl, undecyl, and dodecyl. Examples of alkyl groups include, but are not limited to, octanyl, nonanyl, and decanyl.

[0045] Preferably, R1 and R2 are independently selected from C13-C20 alkenyl groups; more preferably, R1 and R2 are independently selected from C15-C18 alkenyl groups. Preferably, the alkenyl group contains 1 to 3 unsaturated double bonds; more preferably, the alkenyl group contains 1 to 2 unsaturated double bonds.

[0046] Examples of alkenyl include, but are not limited to, decaenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, eicosenyl, heneicosenyl, docosenyl, tricosenyl. In certain embodiments, R1 and R2 are independently selected from 8-heptadecenyl and 9-heptadecenyl.

[0047] According to one embodiment of the present invention, the first ethylene compound is ethylene bisoleamide.

[0048] The content of the first ethylene compound is 20 to 70 parts by weight, preferably 25 to 60 parts by weight. In certain embodiments, the content of the first ethylene compound is 40 to 50 parts by weight.

[0049] The second ethylene compound is shown in formula (II):

[0050]

[0051] R3 and R4 are independently selected from C8 to C15 alkyl groups; preferably, R3 and R4 are independently selected from C10 to C13 alkyl groups; more preferably, R3 and R4 are independently selected from C10 to C12 alkyl groups.

[0052] Examples of alkyl groups include, but are not limited to, octyl, nonyl, decanyl, undecyl, dodecyl, tridecyl.

[0053] According to one embodiment of the present invention, the second ethylene compound is ethylene lauric acid amide.

[0054] The content of the second ethylene compound is 25 to 60 parts by weight, preferably 30 to 55 parts by weight, and more preferably 35 to 50 parts by weight.

[0055] The polyol ester compound is shown in formula (III):

[0056]

[0057] R5, R6, R7 and R8 are independently selected from C1-C3 alkylene groups, R9, R 10 , R 11 and R 12 Each is independently selected from a C11 to C23 alkyl group.

[0058] Preferably, R5, R6, R7 and R8 are independently selected from C1-C2 alkylene groups. Examples of alkylene groups include, but are not limited to, methylene and ethylene.

[0059] Preferably, R9, R 10 , R 11 and R 12 Each of the alkyl groups is independently selected from C13 to C20. Examples of the alkyl group include, but are not limited to, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl.

[0060] According to one embodiment of the present invention, the polyol ester compound is pentaerythritol stearate.

[0061] The amount of the polyol ester compound is 1 to 45 parts by weight. In some embodiments, the amount of the polyol ester compound is 3 to 6 parts by weight. In other embodiments, the amount of the polyol ester compound is 27 to 35 parts by weight.

[0062] The amount of MoS2 used is 0.01 to 0.5 parts by weight; preferably 0.05 to 0.3 parts by weight; more preferably 0.08 to 0.2 parts by weight.

[0063] The second modified component

[0064] The second modified component of the present invention comprises a first ester compound and a second ester compound. Preferably, the second modified component consists of the first ester compound and the second ester compound.

[0065] The first ester compound is selected from methyl oleate, ethyl oleate, propyl oleate, isopropyl oleate, octyl oleate, isooctyl oleate, methyl palmitate, ethyl palmitate, propyl palmitate, isopropyl palmitate, octyl palmitate, isooctyl palmitate, polyethylene glycol dioleate, methyl myristate, ethyl myristate, propyl myristate, isopropyl myristate, octyl myristate, isooctyl myristate, methyl laurate, ethyl laurate, and propyl laurate. Preferably, the first ester compound is selected from one or more of ethyl oleate, isooctyl oleate, methyl palmitate, and methyl laurate. In certain embodiments, the first ester compound is ethyl oleate. In other embodiments, the first ester compound is methyl laurate.

[0066] The content of the first ester compound is 0.5 to 2 parts by volume, preferably 0.8 to 1.5 parts by volume, and more preferably 1 to 1.2 parts by volume.

[0067] The second ester compound is selected from one or more of trimethyl borate, triethyl borate, tripropyl borate, triisopropyl borate, tributyl borate, triisobutyl borate, tri-tert-butyl borate, tri-sec-butyl borate, and triethanolamine borate. Preferably, the second ester compound is selected from triethyl borate, triisopropyl borate, and tributyl borate. In certain embodiments, the second ester compound is tributyl borate. In other embodiments, the second ester compound is triethyl borate.

[0068] The content of the second ester compound is 0.5 to 2 parts by volume, preferably 0.8 to 1.5 parts by volume, and more preferably 1 to 1.2 parts by volume.

[0069] In certain embodiments, the first modifying component includes ethylene bisoleamide, ethylene bislauric acid amide, pentaerythritol stearate, and molybdenum disulfide;

[0070] The second modifying component is selected from one of the following compositions:

[0071] (A) ethyl oleate and tributyl borate;

[0072] (B) 2-ethylhexyl oleate and triisopropyl borate;

[0073] (C) methyl palmitate and tributyl borate;

[0074] (D) Methyl laurate and triethyl borate

[0075] The first modified component of the present invention acts on the coarse alloy powder during the airflow milling process, and the second modified component is used to mix with the fine alloy powder. The first modified component and the second modified component cooperate with each other to effectively improve the fluidity and oxidation resistance of the magnetic powder, and improve the magnetic properties of the magnet such as coercive force, remanence, maximum magnetic energy product, squareness, etc.

[0076] <Preparation method and use of magnetic powder modifier>

[0077] The preparation method of the magnetic powder modifier of the present invention comprises the following steps: (I) mixing a first ethylene compound, a second ethylene compound, a polyol ester compound and MoS2 to obtain a first modified component; (II) mixing a first ester compound and a second ester compound to obtain a second modified component. The selection and dosage of the raw materials are as described above and will not be repeated here. The mixing method can be conventional in the art, such as mechanical mixing.

[0078] The magnetic powder modifier of the present invention can effectively improve the magnetic properties of NdFeB magnets. Preferably, the NdFeB magnets are sintered NdFeB magnets. The magnetic properties are selected from one or more of remanence, coercive force, maximum magnetic energy product, and squareness.

[0079] <Production method of NdFeB magnet>

[0080] The method for producing NdFeB magnets of the present invention comprises the following steps: (1) jet milling; (2) mixing; (3) forming and heat treatment. In some embodiments, the method further comprises preparing a crude alloy powder.

[0081] Steps of Jet Milling

[0082] The mixed crude alloy powder and the first modified component are jet milled to obtain fine alloy powder. The composition of the first modified component is as described above and will not be repeated here. The amount of the first modified component is 0.2 to 0.9‰ of the mass of the crude alloy powder; preferably 0.3 to 0.7‰; more preferably 0.4 to 0.5‰

[0083] The rotation speed of the classifying wheel may be 3500 to 6000 rpm, preferably 3800 to 5300 rpm, and more preferably 4000 to 5000 rpm.

[0084] The jet milling can be carried out under an inert gas atmosphere. Examples of inert gases include, but are not limited to, one or more of nitrogen, helium, neon, and argon. Preferably, the inert gas is nitrogen. The gas pressure of the inert gas can be 0.2 to 0.7 MPa; preferably 0.35 to 0.65 MPa; more preferably 0.4 to 0.6 MPa.

[0085] Oxygen can be added appropriately during the airflow grinding process. The oxygen content can be 5-25 ppm, preferably 10-20 ppm. This helps to improve cutting efficiency.

[0086] The SMD of the fine alloy powder can be 2 to 4.2 μm, preferably 2.5 to 4 μm, and more preferably 2.9 to 3.5 μm. SMD represents the surface average diameter. The repose angle of the fine alloy powder is ≤ 50°, preferably ≤ 45°. The D 90 / D 10 The tap density of the fine alloy powder can be 2.5 to 5; preferably 3.5 to 4.5; more preferably 4 to 5. The tap density of the fine alloy powder can be 2 to 5 g / cm 3 ; preferably 3 to 4.5 g / cm 3 More preferably, 3.5 to 4 g / cm 3 The bulk density of fine alloy powder can be 1.6-3.5 g / cm 3 ; preferably 1.7 to 3 g / cm 3 More preferably, 1.7 to 2 g / cm 3 .

[0087] Mixing steps

[0088] The fine alloy powder and the second modified component are mixed to obtain modified magnetic powder. The composition of the second modified component is as described above and will not be repeated here. The amount of the second modified component is 0.2-0.9‰ of the mass of the fine alloy powder; preferably 0.2-0.7‰; more preferably 0.3-0.6‰.

[0089] The mixing is carried out under oxygen-free conditions. The oxygen-free conditions refer to an oxygen content of ≤100 ppm, preferably an oxygen content of ≤80 ppm, and more preferably an oxygen content of ≤50 ppm.

[0090] The mixing may include secondary mixing. The primary mixing speed may be 100 to 300 rpm; preferably 150 to 250 rpm. The primary mixing time may be 5 to 20 min; preferably 10 to 15 min. The secondary mixing speed may be 400 to 800 rpm; preferably 500 to 700 rpm. The secondary mixing time may be 10 to 30 min; preferably 15 to 25 min.

[0091] Forming and heat treatment steps

[0092] The modified magnetic powder is formed and then heat treated to obtain a NdFeB magnet. Specifically, the modified magnetic powder is oriented and formed in a magnetic field to obtain a green body; the green body is sintered and aged to obtain a NdFeB magnet. Preferably, isostatic pressing is not performed after orientation forming to obtain a green body.

[0093] The magnetic field strength may be 1 to 2.5 T, preferably 1.5 to 2 T. The molding pressure may be 2 to 16 MPa, preferably 10 to 14 MPa. The holding time may be 0.5 to 10 s, preferably 1 to 3 s.

[0094] The density of the green body can be 2.0 to 6.0 g / cm 3 ; preferably 3.5 to 5.5 g / cm 3 More preferably, 3.8 to 4.5 g / cm 3 .

[0095] Sintering can be carried out under vacuum conditions, where vacuum means pressure ≤ 10 -2 Pa; preferably, pressure ≤10 -3 Pa.

[0096] In some embodiments, the green body is sequentially sintered at T1 for t1, sintered at T2 for t2, and sintered at T3 for t3. T1 may be 320-400°C. In some embodiments, T1 is 360-385°C. t1 may be 35-75min. In some embodiments, t1 is 65min. T2 may be 410-570°C. In some embodiments, T2 is 480-520°C. t2 may be 45-85min. In some embodiments, t2 is 50-70min. T3 may be 950-1250°C; preferably 1000-1100°C. t3 may be 2.5-7.5h; preferably 3-6h.

[0097] In certain embodiments, the sintered body is aged at T4 and t4, and aged at T5 and t5, respectively. T4 may be 700-1050°C, preferably 800-950°C, and more preferably 850-950°C. t4 may be 0.5-6h, preferably 0.5-3h, and more preferably 0.5-1h. T5 may be 460-650°C, preferably 480-550°C. t5 may be 1-7h, preferably 3-6h.

[0098] The nitrogen content in the NdFeB magnet may be 285 to 760 ppm, preferably 290 to 600 ppm.

[0099] Steps for preparing crude alloy powder

[0100] The raw materials are smelted to obtain a master alloy. The master alloy is subjected to a rapid solidification belt spinning process to obtain alloy flakes. The alloy flakes are hydrogen crushed to obtain a crude alloy powder. The particle size of the crude alloy powder can range from 30 to 400 μm, preferably from 45 to 325 μm.

[0101] Preferably, the raw materials are smelted in a vacuum or inert atmosphere to obtain a master alloy, which can prevent the master alloy from being oxidized. The smelting can be carried out in a vacuum induction melting furnace.

[0102] The crude alloy powder may be composed of the following elements: PrNd, Cu, Co, Al, Ga, Zr, B and Fe. Of course, the crude Nd-Fe-B alloy powder may contain inevitable impurities, such as C, O, etc.

[0103] The content of PrNd can be 20-40wt%, preferably 25-35wt%, more preferably 30-31wt%. The mass ratio of Pr to Nd can be 25:(50-90), preferably 25:(60-80), more preferably 25:(65-75). The content of Cu is 0.01-0.55wt%, preferably 0.03-0.4wt%, more preferably 0.05-0.2wt%. The content of Co is 0.1-0.8wt%, preferably 0.2-0.7wt%, more preferably 0.3-0.5wt%. The content of Al is 0.2-0.9wt%, preferably 0.3-0.8wt%, more preferably 0.5-0.6wt%. The content of Ga is 0.03-0.6wt%, preferably 0.1-0.5wt%, more preferably 0.2-0.3wt%. The content of Zr is 0.03-0.6 wt%, preferably 0.1-0.5 wt%, more preferably 0.2-0.3 wt%. The content of B is 0.8-1.0 wt%, preferably 0.9-0.95 wt%.

[0104] Embodiments 1 to 4

[0105] Ethylene bisoleamide, ethylene bislauric acid amide, pentaerythritol stearate and MoS2 are mixed to obtain a first modified component.

[0106] One part by volume of the first ester compound and one part by volume of the second ester compound are mixed to obtain a second modified component.

[0107] The selection and dosage of raw materials are shown in Table 1.

[0108] Table 1

[0109]

[0110] Embodiments 5 to 8

[0111] The raw materials for forming NdFeB magnets are melted under vacuum conditions to obtain a master alloy. The master alloy is made into alloy sheets by a rapid solidification belt spinning process. The alloy sheets are hydrogen crushed to obtain a crude alloy powder. The element composition of the crude alloy powder is PrNd, 0.10wt% Cu, 0.4wt% Co, 0.5wt% Al, 0.2wt% Ga, 0.2wt% Zr, 0.92wt% B and the balance Fe.

[0112] The content of PrNd, the proportion of each element in PrNd and the particle size range of the coarse alloy powder are shown in Table 2.

[0113] Table 2

[0114]

[0115] After the first modified component and the coarse alloy powder were mixed, they were jet milled at a classifying wheel speed of 4800 rpm in the presence of nitrogen and oxygen to obtain fine alloy powder. The nitrogen pressure was 0.46 MPa and the oxygen content was 15 ppm.

[0116] The fine alloy powder and the second modified component are mixed in a mixer in the first and second stages in sequence under the condition that the O2 content is less than 50ppm to obtain modified magnetic powder. The first stage mixing is carried out at a rotation speed of 200rpm. The first stage mixing time is 10min. The second stage mixing is carried out at a rotation speed of 600rpm. The second stage mixing time is 20min.

[0117] The modified magnetic powder was oriented and molded in a magnetic field with an intensity of 1.8 T to obtain a green body directly. The molding pressure was 13 MPa and the holding time was 2 s.

[0118] The blank is placed under a pressure of ≤10 -3 Pa, sintered at T1 for t1 time, sintered at T2 for t2 time, and sintered at T3 for t3 time; then air-cooled to 25°C to obtain a sintered body. The sintered body was aged at T4 for t4 time, and aged at T5 for t5 time; then blown with Ar at 25°C and 99.99% purity to cool to 25°C to obtain a NdFeB magnet.

[0119] The NIM-10000HC permanent magnet tester was used to test the NdFeB magnets. The NdFeB magnets were processed into cylinders with a diameter of 10 mm and a height of 10 mm by wire cutting, and the test temperature was 20°C. The test standard was GB / T 3217:2013.

[0120] The raw materials, process parameters, parameters of fine alloy powder, density of green body, density, nitrogen content and magnetic properties of NdFeB magnets are shown in Table 3.

[0121] Table 3

[0122]

[0123]

[0124] Note: SMD stands for surface mean diameter.

[0125] Comparative Example 1

[0126] Except that the first modifying component and the second modifying component are not added, the rest is the same as in Example 1. The magnetic properties of the NdFeB magnet are tested according to the method of Example 1. The parameters of the fine alloy powder, the density of the blank, the density, nitrogen content and magnetic properties of the magnet are shown in Table 4.

[0127] Table 4

[0128] Comparative Example 1 SMD of fine alloy powder (μm) 3.12 <![CDATA[D of fine alloy powder 90 / D 10 > 4.79 Repose angle of fine alloy powder (°) 46.1 <![CDATA[Apparent density of fine alloy powder (g / cm 3 )]]> 1.57 <![CDATA[Tap density of fine alloy powder (g / cm 3 )]]> 3.27 <![CDATA[Density of green body (g / cm 3 )]]> 3.96 Nitrogen content in NdFeB magnets (ppm) 183 <![CDATA[Density of neodymium iron boron magnet (g / cm 3 )]]> 7.45 Br(kGs) of NdFeB magnet 14.19 Hcj(kOe) of NdFeB magnet 15.13 <![CDATA[BH of neodymium iron boron magnet max (MGOe)]]> 48.41 Hk / Hcj of NdFeB magnets (%) 96.6

[0129] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A magnetic powder modifier, characterized in that: The magnetic powder modifier comprises a first modifying component and a second modifying component; The first modified component comprises 20 to 70 parts by weight of a first ethylene compound represented by formula (I), 25 to 60 parts by weight of a second ethylene compound represented by formula (II), 1 to 45 parts by weight of a polyol ester compound represented by formula (III) and 0.01 to 0.5 parts by weight of MoS2; R1 and R2 are independently selected from C10 to C23 alkenyl, Among them, R a An alkyl group selected from C5 to C12, R b An alkylene group selected from C5 to C12; R3 and R4 are independently selected from C8-C15 alkyl groups; R5, R6, R7 and R8 are independently selected from C1-C3 alkylene groups, R9, R 10 , R 11 and R 12 Each independently selected from a C11 to C23 alkyl group; The second modified component includes 0.5 to 2 parts by volume of a first ester compound and 0.5 to 2 parts by volume of a second ester compound; The first ester compound is selected from one or more of methyl oleate, ethyl oleate, propyl oleate, isopropyl oleate, octyl oleate, isooctyl oleate, methyl palmitate, ethyl palmitate, propyl palmitate, isopropyl palmitate, octyl palmitate, isooctyl palmitate, polyethylene glycol dioleate, methyl myristate, ethyl myristate, propyl myristate, isopropyl myristate, octyl myristate, isooctyl myristate, methyl laurate, ethyl laurate, and propyl laurate; The second ester compound is selected from one or more of trimethyl borate, triethyl borate, tripropyl borate, triisopropyl borate, tributyl borate, triisobutyl borate, tri-tert-butyl borate, tri-sec-butyl borate, and triethanolamine borate.

2. The magnetic powder modifier according to claim 1, characterized in that R1 and R2 are independently selected from C10-C23 alkenyl groups containing 1-3 unsaturated double bonds, R3 and R4 are independently selected from C10-C13 alkyl groups, R5-R8 are independently selected from C1-C2 alkylene groups, R9-R 12 Each is independently selected from a C13 to C20 alkyl group.

3. The magnetic powder modifier according to claim 1, characterized in that The first ester compound is selected from one or more of ethyl oleate, isooctyl oleate, methyl palmitate, and methyl laurate; the second ester compound is selected from one or more of triethyl borate, triisopropyl borate, and tributyl borate.

4. The method for preparing a magnetic powder modifier according to any one of claims 1 to 3, characterized in that: The steps include: (I) mixing a first ethylene compound, a second ethylene compound, a polyol ester compound and MoS2 to obtain a first modified component; (II) The first ester compound and the second ester compound are mixed to obtain a second modified component.

5. Use of the magnetic powder modifier according to any one of claims 1 to 3 in improving the magnetic properties of NdFeB magnets, wherein the magnetic properties are selected from one or more of remanence, coercive force, maximum magnetic energy product, and squareness.

6. A method for producing a neodymium iron boron magnet, characterized in that: The steps include: (1) jet milling the mixed crude alloy powder and the first modified component in the magnetic powder modifier according to any one of claims 1 to 3 to obtain fine alloy powder; wherein the amount of the first modified component is 0.2 to 0.9‰ of the mass of the crude alloy powder; (2) mixing fine alloy powder and the second modified component in the magnetic powder modifier according to any one of claims 1 to 3 to obtain modified magnetic powder; wherein the amount of the second modified component is 0.2 to 0.9‰ of the mass of the fine alloy powder; (3) The modified magnetic powder is formed and then heat treated to obtain a NdFeB magnet.

7. The production method according to claim 6, characterized in that: The air flow mill is carried out in the presence of inert gas and oxygen, the inert gas pressure is 0.2-0.7 MPa, the oxygen content is 5-25 ppm, and the classifying wheel speed is 3500-6000 rpm.

8. The production method according to claim 6, characterized in that: Orienting and molding the modified magnetic powder in a magnetic field with an intensity of 1 to 2.5 T to obtain a green body; the molding pressure is 2 to 16 MPa, and the holding time is 0.5 to 10 seconds; Wherein, the orientation molding is not followed by isostatic pressing.

9. The production method according to claim 6, characterized in that: Heat treatment includes the following steps: The formed green body is sequentially sintered at 320-400° C. for 35-75 min, 410-570° C. for 45-85 min, and 950-1250° C. for 2.5-7.5 h to obtain a sintered body; The sintered body is subjected to aging treatment at 700-1050° C. for 0.5-6 h and at 460-650° C. for 1-7 h to obtain a NdFeB magnet.

10. The production method according to any one of claims 6 to 9, characterized in that: The average specific surface diameter of the fine alloy powder is 2 to 4.2 μm, and the D 90 / D 10 The repose angle of fine alloy powder is ≤50°, and the bulk density of fine alloy powder is 1.6-3.5g / cm 3 The tap density of fine alloy powder is 2-5 g / cm 3 ; The content of nitrogen in the NdFeB magnet is 285-760 ppm.

Images