Rare earth iron-based magnetic powder modifier, preparation method and application thereof, and magnet production method

Abstract

The invention discloses a rare earth iron-based magnetic powder modifier, a preparation method, application and a production method of a magnet. The rare earth iron-based magnetic powder modifier comprises a modifying component I and a modifying component II, the modified component I comprises 55-85 parts by weight of an amide compound, 10-50 parts by weight of first higher aliphatic ester and 0.03-0.6 part by weight of a two-dimensional layered compound; the first higher fatty acid is formed by condensing first fatty acid and first fatty alcohol, the first fatty acid contains 8-24 carbon atoms, the first fatty alcohol contains 1-6 carbon atoms, and the first fatty alcohol is selected from one or more of monohydric alcohol, dihydric alcohol or trihydric alcohol; and the modified component II comprises 0.3-2 parts by volume of a second higher aliphatic ester and 0.3-2 parts by volume of a borate compound. The rare earth iron-based magnetic powder modifier can effectively improve the magnetic performance of a neodymium-iron-boron magnet.

Description

Technical Field

[0001] The present invention relates to a rare earth iron-based magnetic powder modifier, a preparation method, a use and a method for producing a magnet, and in particular to a modifier suitable for NdFeB magnetic powder, a preparation method, a use and a method for producing a NdFeB magnet. Background Art

[0002] NdFeB permanent magnet materials have the characteristics of high magnetic properties and good mechanical properties, but their low Curie temperature, poor temperature stability and oxidation resistance limit the improvement of their performance. The magnetic properties of NdFeB permanent magnet materials are closely related to their organizational structure. Powder engineering is an effective method to regulate the organizational structure of NdFeB permanent magnet materials.

[0003] CN110760750A discloses a method for preparing rare earth permanent magnet material, wherein the main alloy in the form of ingot and / or quick-setting thin sheet is crushed, the crushed main alloy is mixed with a first antioxidant, and airflow milled into fine powder. The first antioxidant is at least one of a mixture of polyethylene oxide alkyl ether, polyethylene oxide olefin ether, oleic acid or its salt, stearic acid or its salt, polyol, polyethylene glycol, sorbitol, and sorbitan and stearic acid glyceryl ester. Or the second antioxidant is mixed with the main alloy and additives, and pressed and formed under magnetic field orientation conditions to obtain a blank. The second antioxidant is at least one of a mixture of polyethylene oxide alkyl ether, polyethylene oxide olefin ether, oleic acid or its salt, stearic acid or its salt, polyol, polyethylene glycol, sorbitol, and sorbitan and stearic acid glyceryl ester.

[0004] CN118538496A discloses a method for preparing a sintered NdFeB magnet, wherein an antioxidant and a lubricant are added to the coarse powder obtained by hydrogen crushing and then subjected to airflow milling; an antioxidant, a lubricant and a molding aid are added to the fine powder obtained by airflow milling. The antioxidant is at least one of 1-hexadecanol, triphenylmethanol and calcium stearate, the lubricant is at least one of polyethylene glycol and 120# gasoline, and the molding aid is at least one of glycerol and ethylene glycol.

[0005] The additives used in the above method have limited effect on modifying the magnetic powder and improving the magnetic properties of the magnet. Summary of the invention

[0006] One object of the present invention is to provide a rare earth iron-based 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 rare earth iron-based magnetic powder modifier. Another object of the present invention is to provide a use of the rare earth iron-based magnetic powder modifier. Another object of the present invention is to provide a method for producing a magnet, which can improve the magnetic properties of neodymium iron boron magnets.

[0007] In one aspect, the present invention provides a rare earth iron-based magnetic powder modifier, comprising a modified component I and a modified component II;

[0008] The modified component I comprises 55 to 85 parts by weight of an amide compound as shown in formula (A), 10 to 50 parts by weight of a first higher fatty acid ester and 0.03 to 0.6 parts by weight of a two-dimensional layered compound;

[0009]

[0010] Wherein, R1 is selected from C17-C25 alkenyl;

[0011] The first higher fatty acid is formed by condensation of a first fatty acid and a first fatty alcohol, the first fatty acid contains 8 to 24 carbon atoms, the first fatty alcohol contains 1 to 6 carbon atoms, and the first fatty alcohol is selected from one or more of a monohydric alcohol, a dihydric alcohol or a trihydric alcohol;

[0012] The modified component II comprises 0.3-2 parts by volume of a second higher fatty acid ester and 0.3-2 parts by volume of a borate compound; the borate compound is selected from one or more of the compound represented by formula (B) or triethanolamine borate; the second higher fatty acid ester is formed by condensation of a second fatty acid and a second fatty alcohol, the second fatty acid contains 8-24 carbon atoms, and the second fatty alcohol is a monohydric alcohol or a dihydric alcohol containing 1-12 carbon atoms;

[0013]

[0014] Wherein, R2 to R4 are independently selected from C1 to C6 alkyl groups;

[0015] The two-dimensional layered compound is selected from one or more of MoS2, WS2, MoSe2, and WTe2.

[0016] According to the rare earth iron-based magnetic powder modifier of the present invention, preferably, the first fatty acid is a saturated fatty acid, and the first fatty acid is a monobasic acid; the first fatty alcohol is a saturated fatty alcohol; the second fatty acid is selected from at least one of a saturated fatty acid or a fatty acid containing an unsaturated double bond, and the second fatty alcohol is a saturated fatty alcohol.

[0017] According to the rare earth iron-based magnetic powder modifier of the present invention, preferably, the first fatty acid contains 10 to 20 carbon atoms, and the first fatty alcohol contains 1 to 3 carbon atoms; the second fatty acid contains 10 to 20 carbon atoms, and the second fatty alcohol contains 1 to 8 carbon atoms.

[0018] According to the rare earth iron-based magnetic powder modifier of the present invention, preferably, R1 is selected from C19-C23 alkenyl groups, and R2-R4 are independently selected from C1-C4 alkyl groups.

[0019] According to the rare earth iron-based magnetic powder modifier of the present invention, preferably, the content of the amide compound is 60 to 80 parts by weight, the content of the first higher fatty acid ester is 20 to 40 parts by weight, and the content of the two-dimensional layered compound is 0.05 to 0.3 parts by weight;

[0020] The content of the second higher fatty acid ester is 0.7 to 1.5 parts by volume, and the content of the boric acid ester is 0.7 to 1.5 parts by volume.

[0021] According to the rare earth iron-based magnetic powder modifier of the present invention, preferably, the amide compound is erucamide;

[0022] The first higher fatty acid ester is selected from one or more of lauric acid monoglyceride, palmitic acid monoglyceride, myristic acid monoglyceride, stearic acid monoglyceride, methyl laurate, methyl palmitic acid, methyl myristic acid, and methyl stearate; the first higher fatty acid ester is solid at 20-35° C.;

[0023] The second higher fatty acid ester is selected from one or more of butyl oleate, isooctyl oleate, ethyl oleate, polyethylene glycol dioleate, methyl palmitate, methyl laurate, methyl myristate, and methyl stearate; the second higher fatty acid ester is liquid at 20-35°C;

[0024] The borate ester is selected from one or more of tributyl borate, tripropyl borate, triisopropyl borate, triethyl borate, and triethanolamine borate.

[0025] On the other hand, the present invention provides a method for preparing a rare earth iron-based magnetic powder modifier, comprising the following steps:

[0026] (A) mixing a first raw material including an amide compound, a first higher fatty acid ester and a two-dimensional layered compound to obtain a modified component I;

[0027] (B) A second raw material including a second higher fatty acid ester and a boric acid ester is mixed to obtain a modified component II.

[0028] In yet another aspect, the present invention provides a use of a rare earth iron-based magnetic powder modifier in improving the magnetic properties of a neodymium iron boron magnet.

[0029] In another aspect, the present invention provides a method for producing a magnet, comprising the steps of:

[0030] (1) jet milling the rare earth iron-based alloy coarse powder and the modified component I in the rare earth iron-based magnetic powder modifier to obtain rare earth iron-based alloy fine powder;

[0031] (2) mixing rare earth iron-based alloy fine powder and modified component II in the rare earth iron-based magnetic powder modifier to obtain modified rare earth iron-based magnetic powder;

[0032] (3) The modified rare earth iron-based magnetic powder is formed and then heat treated to obtain a magnet.

[0033] According to the production method of the present invention, preferably, the heat treatment comprises the following steps:

[0034] The formed rare earth iron-based magnet blank is sequentially sintered at 320-400° C. for 35-75 min, sintered at 410-570° C. for 45-85 min, and sintered at 950-1250° C. for 2.5-7.5 h to obtain a rare earth iron-based sintered body;

[0035] The rare earth iron-based sintered body is subjected to aging treatment at 700-1050°C for 0.5-6h, and then subjected to aging treatment at 460-650°C for 1-7h;

[0036] The content of N element in the magnet is 260-780 ppm.

[0037] The components of the rare earth iron-based magnetic powder modifier of the present invention cooperate with each other to effectively improve the magnetic properties of NdFeB magnets. After adding the rare earth iron-based magnetic powder modifier of the present invention to the magnetic powder, the magnetic powder is pressed in one step without isostatic pressing to obtain a high-density blank. DETAILED DESCRIPTION

[0038] 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.

[0039] <Rare earth iron-based magnetic powder modifier>

[0040] The rare earth iron-based magnetic powder modifier of the present invention comprises a modified component I and a modified component II. In certain embodiments, the rare earth iron-based magnetic powder modifier consists of a modified component I and a modified component II. The modified component I and the modified component II are two separate components and are not mixed.

[0041] Modified component I

[0042] The modified component I of the present invention comprises an amide compound, a first higher fatty acid ester and a two-dimensional layered compound.

[0043] The amide compounds of the present invention are shown in formula (A):

[0044]

[0045] In formula (A), R1 is selected from alkenyl of C17 to C25; preferably, R1 is selected from alkenyl of C19 to C23; more preferably, R1 is selected from alkenyl of C20 to C22. The alkenyl preferably contains one unsaturated double bond. Examples of alkenyl include, but are not limited to, 12-heneicosene, 13-heneicosene, 12-hexadecene, and 13-hexadecene. According to one embodiment of the present invention, the amide compound is erucamide.

[0046] The content of the amide compound is 55 to 85 parts by weight, preferably 60 to 80 parts by weight. In certain embodiments, the content of the amide compound is 70 to 73 parts by weight.

[0047] The first higher fatty acid ester of the present invention is formed by condensation of a first fatty acid and a first fatty alcohol. The first higher fatty acid ester is preferably a monoester. A monoester means that the first higher fatty acid ester contains only one ester bond. The first higher fatty acid ester is solid at 20 to 35°C; preferably, the first higher fatty acid ester is solid at 25 to 30°C.

[0048] The first fatty acid of the present invention is preferably a saturated fatty acid. The first fatty acid is preferably a straight-chain fatty acid. The first fatty acid of the present invention is a monobasic acid.

[0049] The first fatty acid contains 8 to 24 carbon atoms; preferably, the first fatty acid contains 10 to 20 carbon atoms; more preferably, the first fatty acid contains 12 to 18 carbon atoms.

[0050] Examples of the first fatty acid include, but are not limited to, lauric acid, myristic acid, palmitic acid, stearic acid.

[0051] The first fatty alcohol of the present invention is selected from one or more of a monohydric alcohol, a dihydric alcohol, and a trihydric alcohol. In some embodiments, the first fatty alcohol is a monohydric alcohol. In some embodiments, the second fatty alcohol is a dihydric alcohol. The first fatty alcohol is a saturated alcohol. Preferably, the first fatty alcohol is a straight-chain fatty alcohol.

[0052] The first fatty alcohol contains 1 to 6 carbon atoms; preferably, contains 1 to 3 carbon atoms. Examples of the first fatty alcohol include, but are not limited to, methanol, ethanol, propanol, and glycerol. Preferably, the first fatty alcohol is selected from one or more of methanol and glycerol.

[0053] The first higher fatty acid ester is preferably selected from one or more of lauric acid monoglyceride, palmitic acid monoglyceride, myristic acid monoglyceride, stearic acid monoglyceride, methyl laurate, methyl palmitate, methyl myristic acid, and methyl stearate. Preferably, the first higher fatty acid ester is selected from one or more of lauric acid monoglyceride, palmitic acid monoglyceride, myristic acid monoglyceride, and methyl stearate.

[0054] The content of the first higher fatty acid ester is 10 to 50 parts by weight, preferably 20 to 40 parts by weight. In certain embodiments, the content of the first higher fatty acid ester is 26 to 32 parts by weight.

[0055] The two-dimensional layered compound is selected from one or more of MoS2, WS2, MoSe2, and WTe2. According to one embodiment of the present invention, the two-dimensional layered compound is MoS2.

[0056] The content of the two-dimensional layered compound is 0.03 to 0.6 parts by weight, preferably 0.05 to 0.3 parts by weight, and more preferably 0.1 to 0.2 parts by weight.

[0057] Modified component II

[0058] The modified component II of the present invention comprises a second higher fatty acid ester and a boric acid ester compound. Preferably, the modified component II consists of a second higher fatty acid ester and a boric acid ester compound.

[0059] The second higher fatty acid ester of the present invention is formed by condensation of a second fatty acid and a second fatty alcohol. The second higher fatty acid ester of the present invention is a monoester. "Monoester" means that the fatty acid ester contains only one ester bond. The second higher fatty acid ester is liquid at 20 to 35°C; preferably, the second higher fatty acid ester is liquid at 25 to 30°C.

[0060] The second fatty acid of the present invention can be a saturated fatty acid or an unsaturated fatty acid. When the second fatty acid is an unsaturated fatty acid, it preferably contains an unsaturated carbon-carbon double bond. Preferably, the second fatty acid is preferably a straight-chain fatty acid. Preferably, the second fatty acid is a monoacid.

[0061] The second fatty acid contains 8 to 24 carbon atoms; preferably, the second fatty acid contains 10 to 20 carbon atoms; more preferably, the second fatty acid contains 12 to 18 carbon atoms.

[0062] Examples of the second fatty acid include, but are not limited to, oleic acid, palmitic acid, myristic acid, lauric acid, stearic acid.

[0063] The second fatty alcohol of the present invention is selected from at least one of a monohydric alcohol or a dihydric alcohol. In some embodiments, the second fatty alcohol is a monohydric alcohol. In some embodiments, the second fatty alcohol is a dihydric alcohol. The second fatty alcohol is a saturated alcohol. Preferably, the second fatty alcohol is a straight-chain fatty alcohol.

[0064] The second fatty alcohol contains 1 to 12 carbon atoms; preferably, contains 1 to 8 carbon atoms. Examples of the second fatty alcohol include, but are not limited to, one or more of methanol, ethanol, propanol, isopropanol, butanol, octanol, isooctyl alcohol, and ethylene glycol. Preferably, the second fatty alcohol is selected from one or more of butanol, isooctyl alcohol, and methanol.

[0065] Preferably, the second higher fatty acid ester is selected from one or more of butyl oleate, isooctyl oleate, ethyl oleate, polyethylene glycol dioleate, methyl palmitate, methyl laurate, methyl myristate, and methyl stearate; more preferably, the second higher fatty acid ester is selected from one or more of butyl oleate, isooctyl oleate, methyl palmitate, and methyl laurate.

[0066] The content of the second higher fatty acid ester is 0.3 to 2 parts by volume, preferably 0.7 to 1.5 parts by volume, and more preferably 1 to 1.2 parts by volume.

[0067] The borate compound of the present invention is selected from one or more of the compounds represented by formula (B) or triethanolamine borate.

[0068]

[0069] In formula (B), R2 to R4 are independently selected from C1 to C6 alkyl groups; preferably, they are independently selected from C1 to C4 alkyl groups. In certain embodiments, R2 to R4 are the same group.

[0070] Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, neopentyl, hexyl, 2-methylpentyl, 3-methylpentyl, 2,3-dimethylbutyl, 2,2-dimethylbutyl.

[0071] Examples of borate esters include, but are not limited to, tributyl borate, triisopropyl borate, triethyl borate.

[0072] The content of the borate ester is 0.3 to 2 parts by volume, preferably 0.7 to 1.5 parts by volume, and more preferably 1 to 1.2 parts by volume.

[0073] The modified component I and the modified component II of the present invention are respectively mixed with the rare earth iron-based alloy coarse powder and the rare earth iron-based alloy fine powder during the air flow milling process, and the two 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 the coercive force, remanence, maximum magnetic energy product, and squareness.

[0074] <Preparation method of rare earth iron-based magnetic powder modifier>

[0075] The method for preparing the rare earth iron-based magnetic powder modifier of the present invention comprises: (A) a step of preparing a modified component I; and (B) a step of preparing a modified component II.

[0076] Steps for preparing modified component I

[0077] The present invention mixes a first raw material including an amide compound, a first higher fatty acid ester and a two-dimensional layered compound to obtain a modified component I. In some embodiments, the first raw material consists of an amide compound, a first higher fatty acid ester and a two-dimensional layered compound. The selection and dosage of the amide compound and the first higher fatty acid ester are as described above, and the dosage of MoS2 is as described above.

[0078] The mixing method may be a commonly used method in the art, such as mechanical mixing, and the mixing method is not limited here.

[0079] Steps for preparing modified component II

[0080] The present invention mixes the second raw material including the second higher fatty acid ester and boric ester to obtain modified component II. In certain embodiments, the second raw material consists of the second higher fatty acid ester and boric ester. The selection and dosage of the second higher fatty acid ester and boric ester are as described above and will not be repeated here.

[0081] The mixing method may be a commonly used method in the art, such as mechanical mixing, and the mixing method is not limited here.

[0082] <Application of rare earth iron-based magnetic powder modifier>

[0083] The rare earth iron-based magnetic powder modifier of the present invention can improve the magnetic properties of NdFeB magnets. Therefore, the present invention provides a use of a rare earth iron-based magnetic powder modifier in improving the magnetic properties of NdFeB magnets. The magnetic properties can be selected from one or more of the maximum magnetic energy product, squareness, coercive force, and remanence. The NdFeB magnet is preferably a sintered NdFeB magnet.

[0084] <Magnet Production Method>

[0085] The method for producing a magnet of the present invention is applicable to rare earth iron-based magnets, preferably to neodymium iron boron magnets. The method for producing a magnet of the present invention comprises the following steps: (1) a step of modifying a rare earth iron-based alloy coarse powder; (2) a step of modifying a rare earth iron-based alloy fine powder; and (3) a step of forming and heat treating. In certain embodiments, the method further comprises the steps of smelting, rapid solidification strip throwing and hydrogen crushing.

[0086] Steps for modifying rare earth iron-based alloy coarse powder

[0087] The present invention jet mills the rare earth iron-based alloy coarse powder and the modified component I to obtain the rare earth iron-based alloy fine powder. Specifically, the rare earth iron-based alloy coarse powder after initial mixing and the modified component I are jet milled to obtain the rare earth iron-based alloy fine powder. The composition of the modified component I is as described above and will not be repeated here.

[0088] The amount of the modified component I is 0.1-1 wt‰ of the rare earth iron-based alloy coarse powder; preferably 0.3-0.8‰; more preferably 0.4-0.5‰.

[0089] The rotation speed of the classifying wheel may be 3000 to 6500 rpm, preferably 3500 to 5500 rpm, and more preferably 4500 to 5200 rpm.

[0090] 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 N2, He, Ne, and Ar. Preferably, the inert gas is N2. 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.

[0091] During the jet milling process, O2 can be appropriately added to the inert gas. The O2 content can be 5 to 25 ppm, preferably 10 to 20 ppm. This helps to improve the cutting efficiency.

[0092] Some physical parameters of the obtained rare earth iron-based alloy fine powder are as follows:

[0093] The SMD (specific surface mean diameter) may be 1.8 to 4.5 μm, preferably 2 to 4 μm, and more preferably 2.5 to 3.5 μm.

[0094] The angle of repose is less than or equal to 50°; preferably, less than or equal to 45°; more preferably, less than or equal to 44°.

[0095] The tap density 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 .

[0096] The bulk density can be 1.6~3.5g / cm 3 ; preferably 1.7 to 3 g / cm 3 More preferably, 1.7 to 1.9 g / cm 3 .

[0097] D 90 / D 10 It may be 2.5 to 5; preferably 3.5 to 5; more preferably 4 to 5.

[0098] Steps for modifying rare earth iron-based alloy fine powder

[0099] The rare earth iron-based alloy fine powder and the modified component II are mixed to obtain modified rare earth iron-based magnetic powder.

[0100] The amount of modified component II is 0.1-1 wt‰ of the rare earth iron-based alloy fine powder; preferably 0.2-0.7 wt‰; more preferably 0.3-0.6 wt‰. The composition and amount of modified component II are as described above and will not be repeated here.

[0101] The rare earth iron-based alloy fine powder and the modified component II are preferably mixed under oxygen-free conditions. This can avoid the negative impact of oxygen on the rare earth iron-based alloy magnetic powder. The oxygen-free condition means that the oxygen content is less than or equal to 100 ppm; preferably, the oxygen content is less than or equal to 80 ppm; more preferably, the oxygen content is less than or equal to 50 ppm.

[0102] The rare earth iron-based alloy fine powder and the modified component II may be mixed at a rotation speed of r1 and then mixed at a rotation speed of r2.

[0103] r1 may be 100 to 300 rpm, preferably 150 to 250 rpm, and more preferably 180 to 220 rpm.

[0104] The mixing time under the rotation speed condition of r1 can be 3 to 25 min, preferably 5 to 20 min, and more preferably 10 to 15 min.

[0105] r2 may be 350 to 850 rpm, preferably 550 to 750 rpm, and more preferably 600 to 700 rpm.

[0106] The mixing time under the rotation speed condition of r2 can be 5 to 40 min, preferably 10 to 30 min, and more preferably 15 to 25 min.

[0107] Forming and heat treatment steps

[0108] The invention forms modified rare earth iron-based magnetic powder and then performs heat treatment to obtain a magnet.

[0109] The modified rare earth iron-based magnetic powder is oriented and formed in a magnetic field to obtain a rare earth iron-based magnet blank. Preferably, after the oriented forming, isostatic pressing is not performed to obtain the rare earth iron-based magnet blank.

[0110] The magnetic field strength may be 1 to 2.5 T, preferably 1.5 to 2.5 T, and more preferably 1.5 to 2 T.

[0111] The molding pressure may be 2 to 16 MPa, preferably 10 to 14 MPa, and more preferably 12 to 13 MPa.

[0112] The holding time may be 0.5 to 10 seconds, preferably 1 to 5 seconds, and more preferably 2 to 3 seconds.

[0113] The density of rare earth iron-based magnet blanks can be 2.0 to 6.0 g / cm3 ; preferably 3.5 to 5.5 g / cm 3 More preferably, 3.8 to 4.5 g / cm 3 .

[0114] The present invention heat treats the rare earth iron-based magnet blank to obtain the magnet. Preferably, the heat treatment includes sintering and aging treatment.

[0115] Sintering can be carried out under vacuum conditions, where vacuum means pressure ≤ 10 -2 Pa; preferably, the pressure ≤ 10 -3 Pa.

[0116] Preferably, the rare earth iron-based magnet blank is sintered at a temperature of T1, a temperature of T2, and a temperature of T3 in sequence.

[0117] T1 may be 320-400° C. In certain embodiments, T1 is 360-385° C.

[0118] The sintering time at temperature T1 may be 35 to 75 minutes. In certain embodiments, the sintering time at temperature T1 is 40 to 65 minutes.

[0119] T2 may be 410 to 570° C. In certain embodiments, T2 is 480 to 520° C.

[0120] The sintering time at T2 temperature may be 45 to 85 minutes. In certain embodiments, the sintering time at T2 temperature is 50 to 70 minutes.

[0121] T3 may be 950-1250°C, preferably 1000-1100°C.

[0122] The sintering time at the T3 temperature may be 2.5 to 7.5 hours; preferably, the sintering time at the T3 temperature is 3 to 6 hours.

[0123] Preferably, the rare earth iron-based sintered body obtained by sintering is subjected to aging treatment at a temperature of T4, and then subjected to aging treatment at a temperature of T5.

[0124] T4 may be 700 to 1050°C, preferably 800 to 950°C, and more preferably 850 to 950°C.

[0125] The time of aging treatment at T4 temperature can be 0.5 to 6 hours, preferably 0.5 to 3 hours, and more preferably 0.5 to 1 hour.

[0126] T5 may be 460 to 650°C, preferably 480 to 550°C.

[0127] The aging treatment time at T5 temperature can be 1 to 7 hours, preferably 3 to 6 hours.

[0128] The N content in the magnet may be 260 to 780 ppm, preferably 290 to 600 ppm.

[0129] The steps of melting, rapid solidification, strip throwing and hydrogen crushing

[0130] 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 rare earth iron-based alloy coarse powder. The particle size of the rare earth iron-based alloy coarse powder can range from 30 to 400 μm, preferably 45 to 325 μm.

[0131] 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.

[0132] The rare earth iron-based alloy coarse powder includes Pr, Nd, Cu, Co, Al, Ga, Zr, B and Fe. In some embodiments, the rare earth iron-based alloy coarse powder consists of Pr, Nd, Cu, Co, Al, Ga, Zr, B and Fe. Of course, the rare earth iron-based alloy coarse powder may contain unavoidable impurities. For example, C, O, etc.

[0133] The total content of Pr and Nd may be 20 to 40 parts by weight, preferably 25 to 35 parts by weight, and more preferably 30 to 31 parts by weight.

[0134] The mass ratio of Pr to Nd may be 25:(50-90); preferably 25:(60-80); and more preferably 25:(65-75).

[0135] The content of Cu is 0.01 to 0.55 parts by weight, preferably 0.03 to 0.4 parts by weight, and more preferably 0.05 to 0.2 parts by weight.

[0136] The content of Co is 0.1 to 0.8 parts by weight, preferably 0.2 to 0.7 parts by weight, and more preferably 0.3 to 0.5 parts by weight.

[0137] The content of Al is 0.2 to 0.9 parts by weight, preferably 0.3 to 0.8 parts by weight, and more preferably 0.5 to 0.6 parts by weight.

[0138] The content of Ga is 0.03 to 0.6 parts by weight, preferably 0.1 to 0.5 parts by weight, and more preferably 0.2 to 0.3 parts by weight.

[0139] The content of Zr is 0.03 to 0.6 parts by weight, preferably 0.1 to 0.5 parts by weight, and more preferably 0.2 to 0.3 parts by weight.

[0140] The content of B is 0.8 to 1.0 parts by weight, preferably 0.9 to 0.95 parts by weight.

[0141] Embodiments 1 to 4

[0142] Erucic acid amide, the first higher fatty acid ester and MoS2 are mixed to obtain a modified component I. 1 part by volume of the second higher fatty acid ester and 1 part by volume of a boric acid ester are mixed to obtain a modified component II.

[0143] The selection and dosage of raw materials are shown in Table 1.

[0144] Table 1

[0145]

[0146] Embodiments 5 to 8

[0147] The raw materials are smelted 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 rare earth iron-based alloy coarse powder with a particle size range of 45 to 325 μm. The rare earth iron-based alloy coarse powder consists of Pr, Nd, 0.10 parts by weight of Cu, 0.4 parts by weight of Co, 0.5 parts by weight of Al, 0.2 parts by weight of Ga, 0.2 parts by weight of Zr, 0.92 parts by weight of B and Fe. The contents of Pr, Nd and Fe are shown in Table 2.

[0148] Table 2

[0149]

[0150] The rare earth iron-based alloy coarse powder and the modified component I after the initial mixing were subjected to jet milling to obtain rare earth iron-based alloy fine powder. The jet milling conditions were as follows: the classifying wheel speed was 4800 rpm; it was carried out under nitrogen and oxygen atmosphere, the nitrogen pressure was 0.46 MPa, and the oxygen content was 15 ppm. The amount of modified component I and the physical properties of the rare earth iron-based alloy fine powder are shown in Table 3.

[0151] Table 3

[0152]

[0153] Note: SMD stands for surface mean diameter.

[0154] The rare earth iron-based alloy fine powder and the modified component II were mixed at 200 rpm for 10 min and then at 600 rpm for 20 min under the condition that the O2 content was less than 50 ppm to obtain modified rare earth iron-based magnetic powder.

[0155] The modified rare earth iron-based magnetic powder was oriented and molded in a magnetic field with an intensity of 1.8 T to directly obtain a rare earth iron-based magnet blank. The molding pressure was 13 MPa and the holding time was 2 s.

[0156] The selection and dosage of modified component II and the density of the rare earth iron-based magnet blank are shown in Table 4.

[0157] Table 4

[0158]

[0159] The rare earth iron-based magnet 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 rare earth iron-based sintered body. The rare earth iron-based sintered body was aged at T4 for t4 time, and at T5 for t5 time; then blown with Ar at 25°C and 99.99% purity to cool to 25°C to obtain a magnet. The density of the magnet is 7.56g / cm 3 .

[0160] The sintering and aging treatment conditions are shown in Table 5, and the content of N element in the magnet is shown in Table 5.

[0161] Table 5

[0162]

[0163] The magnet was tested using a NIM-10000HC permanent magnet tester. The magnet was processed into a cylinder 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. The results are shown in Table 6.

[0164] Table 6

[0165]

[0166]

[0167] Comparative Example 1

[0168] Except that the modified component I and the modified component II are not added, the rest is the same as in Example 1. The magnetic properties of the magnet are tested according to the method of Example 1. The parameters of the rare earth iron-based alloy fine powder, the density of the rare earth iron-based magnet blank, the density, nitrogen content and magnetic properties of the magnet are shown in Table 7.

[0169] Table 7

[0170]

[0171] 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 rare earth iron-based magnetic powder modifier, characterized in that: The rare earth iron-based magnetic powder modifier comprises a modified component I and a modified component II; The modified component I comprises 55 to 85 parts by weight of an amide compound as shown in formula (A), 10 to 50 parts by weight of a first higher fatty acid ester and 0.03 to 0.6 parts by weight of a two-dimensional layered compound; Wherein, R1 is selected from C17-C25 alkenyl; The first higher fatty acid is formed by condensation of a first fatty acid and a first fatty alcohol, the first fatty acid contains 8 to 24 carbon atoms, the first fatty alcohol contains 1 to 6 carbon atoms, and the first fatty alcohol is selected from one or more of a monohydric alcohol, a dihydric alcohol or a trihydric alcohol; The modified component II comprises 0.3-2 parts by volume of a second higher fatty acid ester and 0.3-2 parts by volume of a borate compound; the borate compound is selected from one or more of the compound represented by formula (B) or triethanolamine borate; the second higher fatty acid ester is formed by condensation of a second fatty acid and a second fatty alcohol, the second fatty acid contains 8-24 carbon atoms, and the second fatty alcohol is a monohydric alcohol or a dihydric alcohol containing 1-12 carbon atoms; Wherein, R2 to R4 are independently selected from C1 to C6 alkyl groups; The two-dimensional layered compound is selected from one or more of MoS2, WS2, MoSe2, and WTe2.

2. The rare earth iron-based magnetic powder modifier according to claim 1, characterized in that: The first fatty acid is a saturated fatty acid, the first fatty acid is a monobasic acid; the first fatty alcohol is a saturated fatty alcohol; the second fatty acid is selected from at least one of a saturated fatty acid or a fatty acid containing an unsaturated double bond, and the second fatty alcohol is a saturated fatty alcohol.

3. The rare earth iron-based magnetic powder modifier according to claim 1, characterized in that: The first fatty acid contains 10 to 20 carbon atoms, and the first fatty alcohol contains 1 to 3 carbon atoms; the second fatty acid contains 10 to 20 carbon atoms, and the second fatty alcohol contains 1 to 8 carbon atoms.

4. The rare earth iron-based magnetic powder modifier according to claim 1, characterized in that: R1 is selected from C19 to C23 alkenyl groups, and R2 to R4 are each independently selected from C1 to C4 alkyl groups.

5. The rare earth iron-based magnetic powder modifier according to claim 1, characterized in that: The content of the amide compound is 60 to 80 parts by weight, the content of the first higher fatty acid ester is 20 to 40 parts by weight, and the content of the two-dimensional layered compound is 0.05 to 0.3 parts by weight; The content of the second higher fatty acid ester is 0.7 to 1.5 parts by volume, and the content of the boric acid ester is 0.7 to 1.5 parts by volume.

6. The rare earth iron-based magnetic powder modifier according to claim 1, characterized in that: The amide compound is erucamide; The first higher fatty acid ester is selected from one or more of lauric acid monoglyceride, palmitic acid monoglyceride, myristic acid monoglyceride, stearic acid monoglyceride, methyl laurate, methyl palmitic acid, methyl myristic acid, and methyl stearate; the first higher fatty acid ester is solid at 20-35° C.; The second higher fatty acid ester is selected from one or more of butyl oleate, isooctyl oleate, ethyl oleate, polyethylene glycol dioleate, methyl palmitate, methyl laurate, methyl myristate, and methyl stearate; the second higher fatty acid ester is liquid at 20-35°C; The borate ester is selected from one or more of tributyl borate, tripropyl borate, triisopropyl borate, triethyl borate, and triethanolamine borate.

7. The method for preparing the rare earth iron-based magnetic powder modifier according to any one of claims 1 to 6, characterized in that: The steps include: (A) mixing a first raw material including an amide compound, a first higher fatty acid ester and a two-dimensional layered compound to obtain a modified component I; (B) A second raw material including a second higher fatty acid ester and a boric acid ester is mixed to obtain a modified component II.

8. Use of the rare earth iron-based magnetic powder modifier according to any one of claims 1 to 6 in improving the magnetic properties of NdFeB magnets.

9. A method for producing a magnet, characterized in that: The steps include: (1) jet milling a rare earth iron-based alloy coarse powder and a modified component I in the rare earth iron-based magnetic powder modifier according to any one of claims 1 to 6 to obtain a rare earth iron-based alloy fine powder; (2) mixing rare earth iron-based alloy fine powder and the modified component II in the rare earth iron-based magnetic powder modifier according to any one of claims 1 to 6 to obtain modified rare earth iron-based magnetic powder; (3) The modified rare earth iron-based magnetic powder is formed and then heat treated to obtain a magnet.

10. The production method according to claim 9, characterized in that: Heat treatment includes the following steps: The formed rare earth iron-based magnet blank is sequentially sintered at 320-400° C. for 35-75 min, sintered at 410-570° C. for 45-85 min, and sintered at 950-1250° C. for 2.5-7.5 h to obtain a rare earth iron-based sintered body; The rare earth iron-based sintered body is subjected to aging treatment at 700-1050°C for 0.5-6h, and then subjected to aging treatment at 460-650°C for 1-7h; The content of N element in the magnet is 260-780 ppm.

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