NdFeB magnetic powder composite modifier, preparation method and application thereof and preparation method of magnet

Abstract

The invention discloses an NdFeB magnetic powder composite modifier, a preparation method and application thereof and a preparation method of a magnet. The NdFeB magnetic powder composite modifier comprises a modification component A and a modification component B, the modified component A comprises 60-85 parts by weight of a first amide compound, 15-35 parts by weight of a second amide compound and 1-10 parts by weight of a third amide compound; and the modified component B comprises fatty acid ester and boric acid ester in a volume ratio of 1: (0.3-3). The NdFeB magnetic powder composite modifier can effectively improve the magnetic performance of a neodymium-iron-boron magnet.

Description

Technical Field

[0001] The invention relates to a NdFeB magnetic powder composite modifier and a preparation method and application thereof, and a method for preparing a magnet. Background Art

[0002] NdFeB magnets have excellent magnetic properties and are widely used in aerospace, network communications, automation and other fields. At present, there are higher requirements for the magnetic properties of NdFeB magnets.

[0003] CN115331941A discloses a modification method for sintered NdFeB magnetic powder, which uses inert gas to exhaust oxygen from the mixing chamber of a high-efficiency shear mixer to make its oxygen content less than 50ppm; under the protection of an inert atmosphere, the sintered NdFeB magnetic powder is added to the mixing chamber through an atomized liquid modifier or a suspended solid modifier; the sintered NdFeB magnetic powder is sheared and mixed by a high-efficiency shear mixer, and the remaining liquid modifier or solid modifier is added by a high-pressure inert gas spray device or a solid dispersing device during the mixing process; after the mixing is completed, the powder is connected to an inert gas storage tank to obtain modified sintered NdFeB magnetic powder. The liquid modifier is one or more of dimethylformamide, methyl octanoate, n-octane, acetone, petroleum ether, aviation gasoline, silicone oil, and ethylene glycol. The solid modifier is aluminate coupling agent, polyamide wax powder, ethylene bis stearamide, benzoic acid, zinc stearate, paraffin, ZrO 2 、Nano Al 2 O 3 This method has limited effect on the fluidity modification of NdFeB magnetic powder and limited improvement of the magnetic properties of sintered magnets.

[0004] CN117936258A discloses a process for preparing NdFeB magnets, wherein tri-aminopropyltriethoxysilane and polyvinylpyrrolidone are added to an anhydrous ethanol solution, mixed evenly to obtain a modifier solvent, NdFeB magnetic powder is added to the modifier solution, dispersed, stirred and dried to obtain dried powder, the dried powder is mixed with an acetone resin solution, stirred and dried to obtain modified NdFeB magnetic powder. This process has limited effect on improving the magnetic properties of NdFeB magnets. Summary of the invention

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

[0006] In one aspect, the present invention provides a NdFeB magnetic powder composite modifier, comprising a modified component A and a modified component B;

[0007] The modified component A comprises 60 to 85 parts by weight of a first amide compound, 15 to 35 parts by weight of a second amide compound and 1 to 10 parts by weight of a third amide compound;

[0008] The first amide compound is shown in formula (A):

[0009]

[0010] Among them, R 1 A chain alkyl or alkenyl group selected from C8 to C19;

[0011] The second amide compound is represented by formula (B) or formula (C):

[0012]

[0013] Among them, R 2 A chain alkyl or alkenyl group selected from C20 to C25;

[0014]

[0015] Among them, R 3 and R 4 are independently selected from alkyl or alkenyl; 3 and R 4 The sum of the number of carbon atoms contained in is 20 to 25;

[0016] The third amide compound is represented by formula (D) or formula (E):

[0017]

[0018] Among them, R 5 and R 6 are independently selected from alkyl or alkenyl; 5 and R 6 The sum of the number of carbon atoms contained in is 30 to 43;

[0019]

[0020] Among them, R 7 and R 8 are independently selected from alkyl or alkenyl; 7 and R 8 The sum of the number of carbon atoms contained in is 30 to 43;

[0021] The modified component B includes fatty acid ester and boric acid ester in a volume ratio of 1: (0.3-3).

[0022] According to the NdFeB magnetic powder composite modifier of the present invention, preferably, the fatty acid ester is as shown in formula (F):

[0023]

[0024] Among them, R 9 is selected from a C8-C20 alkyl or alkenyl group, R 10 Selected from C1-C10 chain alkyl groups.

[0025] According to the NdFeB magnetic powder composite modifier of the present invention, preferably, the borate ester is as shown in formula (G):

[0026]

[0027] Among them, R 11 ~R 13 Each is independently selected from C1 to C6 chain alkyl.

[0028] According to the NdFeB magnetic powder composite modifier of the present invention, preferably, R 1 is selected from a C10-C18 alkyl or alkenyl group, R 2 is selected from a C21-C23 alkyl or alkenyl group, R 3 and R 4 are independently selected from C9-C13 alkyl or alkenyl groups, R 5 is selected from a C12-C23 alkyl or alkenyl group, R 6 is selected from a C15-C19 alkyl or alkenyl group, R 7 and R 8 Each is independently selected from a C18-C24 alkyl or alkenyl group.

[0029] According to the NdFeB magnetic powder composite modifier of the present invention, preferably, R 9 is selected from a C10-C18 alkyl or alkenyl group, R 10 A chain alkyl group selected from C1 to C8.

[0030] According to the NdFeB magnetic powder composite modifier of the present invention, preferably, R 11 ~R 13 Same, R 11 ~R 13 Each is independently selected from C1 to C4 chain alkyl.

[0031] On the other hand, the present invention provides a method for preparing the above-mentioned NdFeB magnetic powder composite modifier, comprising the following steps:

[0032] (A) Mix raw material A including a first amide compound, a second amide compound, and a third amide compound to obtain modified component A;

[0033] (B) Mix raw material B including a fatty acid ester and a borate ester to obtain modified component B.

[0034] On the other hand, the present invention provides the use of the above NdFeB magnetic powder composite modifier in improving the magnetic properties of NdFeB magnets.

[0035] According to the use of the present invention, preferably, the magnetic properties are selected from one or more of remanence, coercivity, maximum magnetic energy product, and squareness; the NdFeB magnet is a sintered NdFeB magnet.

[0036] On the other hand, the present invention provides a method for preparing an NdFeB magnet, including the following steps:

[0037] (1) Jet mill the NdFeB alloy coarse powder and modified component A in the above NdFeB magnetic powder composite modifier to obtain NdFeB alloy fine powder;

[0038] (2) Mix the NdFeB alloy fine powder and modified component B in the above NdFeB magnetic powder composite modifier to obtain modified NdFeB alloy powder;

[0039] (3) Shape and heat-treat the modified NdFeB alloy powder to obtain an NdFeB magnet.

[0040] The components of the NdFeB magnetic powder composite modifier of the present invention cooperate with each other, can effectively improve the lubricating performance and antioxidant performance of the magnetic powder, are easy to compact, are easy to desorb, avoid exceeding the standard of impurity elements due to difficult removal of the modifier during sintering, and improve the magnetic properties of the NdFeB magnet. Detailed Embodiments

[0041] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0042] <NdFeB Magnetic Powder Composite Modifier>

[0043] The NdFeB magnetic powder composite modifier of the present invention includes modified component A and modified component B. In some embodiments, the NdFeB magnetic powder composite modifier consists of modified component A and modified component B. Modified component A and modified component B are two separate components and do not mix with each other.

[0044] Modified component A

[0045] The modified component A of the present invention includes a first amide compound, a second amide compound, and a third amide compound.

[0046] The first amide compound of the present invention is shown in formula (A):

[0047]

[0048] Among them, R 1 is selected from C8-C19 alkyl or alkenyl; preferably, R 1 is selected from C10-C18 alkyl or alkenyl; more preferably, R 1 Selected from C11-C17 alkyl or alkenyl groups.

[0049] The alkyl group may be a straight chain alkyl group or a branched chain alkyl group; preferably, a straight chain alkyl group. The alkenyl group may be a straight chain alkenyl group or a branched chain alkenyl group; preferably, a straight chain alkenyl group. The alkenyl group may contain 1 to 3 unsaturated double bonds; preferably, it contains 1 to 2 unsaturated double bonds; more preferably, it contains 1 unsaturated double bond.

[0050] R 1 Examples include, but are not limited to, undecyl, undecanyl, pentadecyl, pentadecenyl, heptadecyl, heptadecenyl, nonadecyl, nonadecenyl.

[0051] Examples of the first amide compound include, but are not limited to, one or more of lauramide, hexadecamide, oleamide, stearic acid amide, and eicosamide. Preferably, the first amide compound is selected from one or more of lauramide, hexadecamide, stearic acid amide, and oleamide.

[0052] The content of the first amide compound is 60 to 85 parts by weight, preferably 65 to 80 parts by weight, and more preferably 68 to 75 parts by weight.

[0053] The second amide compound of the present invention is represented by formula (B) or formula (C):

[0054]

[0055] Among them, R 2 is selected from a C20-C25 alkyl or alkenyl group; preferably, R 2 is selected from a C21-C23 alkyl or alkenyl group; more preferably, R 2 Selected from C21-C22 alkyl or alkenyl groups.

[0056] The alkyl group may be a straight chain alkyl group or a branched chain alkyl group; preferably, a straight chain alkyl group. The alkenyl group may be a straight chain alkenyl group or a branched chain alkenyl group; preferably, a straight chain alkenyl group. The alkenyl group may contain 1 to 3 unsaturated double bonds; preferably, it contains 1 to 2 unsaturated double bonds; more preferably, it contains 1 unsaturated double bond.

[0057] R2 Examples of include, but are not limited to, one or more of eicosyl, eicosenyl, heneicosyl, dodecenyl, docosyl, docosenyl, tricosyl, and tricosenyl.

[0058]

[0059] Among them, R 3 and R 4 are independently selected from alkyl or alkenyl groups; preferably, R 3 and R 4 R are independently selected from chain alkyl. 3 and R 4 The sum of the carbon atoms contained in is 20-25; preferably 21-24; more preferably 22-23.

[0060] R 3 and R 4 are independently selected from C9-C13 alkyl or alkenyl groups; preferably, R 3 and R 4 are independently selected from C10-C12 alkyl or alkenyl groups; more preferably, R 3 and R 4 are independently selected from C11 to C12 alkyl or alkenyl groups. 3 and R 4 Preferably, R 3 and R 4 same.

[0061] The alkyl group may be a straight chain alkyl group or a branched chain alkyl group; preferably, a straight chain alkyl group. The alkenyl group may be a straight chain alkenyl group or a branched chain alkenyl group; preferably, a straight chain alkenyl group. The alkenyl group may contain 1 to 3 unsaturated double bonds; preferably, it contains 1 to 2 unsaturated double bonds; more preferably, it contains 1 unsaturated double bond.

[0062] R 3 and R 4 Examples of include, but are not limited to, decanyl, undecyl, dodecyl, decenyl, undecenyl, dodecenyl.

[0063] Examples of the second amide compound include, but are not limited to, erucic acid amide, behenic acid amide, and ethylene bislauric acid amide.

[0064] The content of the second amide compound is 15 to 35 parts by weight, preferably 20 to 30 parts by weight. In certain embodiments, the content of the second amide compound is 24 to 27 parts by weight.

[0065] The third amide compound is as described by formula (D) or formula (E):

[0066]

[0067] Among them, R 5 and R 6 R are independently selected from alkyl or alkenyl. 5 and R 6 The sum of the carbon atoms contained in is 30-43; preferably 32-40; more preferably 33-39.

[0068] R 5 is selected from a C12-C23 alkyl or alkenyl group; preferably, R 5 Alkyl or alkenyl selected from C15 to C21. The alkyl group may be a straight chain alkyl group or a branched chain alkyl group. Preferably, the alkyl group is a straight chain alkyl group. The alkenyl group may be a straight chain alkenyl group or a branched chain alkenyl group. Preferably, the alkenyl group is a straight chain alkenyl group.

[0069] R 5 Examples of include, but are not limited to, pentadecyl, pentadecenyl, hexadecyl, hexadecenyl, heptadecyl, heptadecenyl, octadecyl, octadecenyl, nonadecyl, nonadecenyl, eicosyl, eicosenyl, heneicosyl, heneicosenyl. Preferably, R 5 Selected from pentadecyl and heneicosene.

[0070] R 6 is selected from a C15-C19 alkyl or alkenyl group; preferably, R 6 is selected from a C16-C18 alkyl or alkenyl group; more preferably, R 6 Alkyl or alkenyl selected from C17 to C18. The alkyl group may be a straight chain alkyl group or a branched chain alkyl group. Preferably, the alkyl group is a straight chain alkyl group. The alkenyl group may be a straight chain alkenyl group or a branched chain alkenyl group. Preferably, the alkenyl group is a straight chain alkenyl group.

[0071] R 6 Examples of include, but are not limited to, hexadecyl, hexadecenyl, heptadecyl, heptadecenyl, octadecyl, octadecenyl. Preferably, R 6 Selected from octadecyl or octadecenyl.

[0072]

[0073] Among them, R 7 and R 8 R are independently selected from alkyl or alkenyl. 7 and R 8 The sum of the carbon atoms contained in is 30 to 43, preferably 35 to 42, and more preferably 40 to 42.

[0074] R 7 and R8 are independently selected from C18 to C24 alkyl or alkenyl groups; preferably, R 7 and R 8 are independently selected from C19 to C23 alkyl or alkenyl groups; more preferably, R 7 and R 8 are independently selected from C20-C21 alkyl or alkenyl groups. 7 and R 8 Preferably, R 3 and R 4 same.

[0075] The alkyl group may be a straight chain alkyl group or a branched chain alkyl group; preferably, it is a straight chain alkyl group. The alkenyl group may be a straight chain alkenyl group or a branched chain alkenyl group; preferably, it is a straight chain alkenyl group. The alkenyl group may contain 1 to 3 unsaturated double bonds; preferably, it contains 1 to 2 unsaturated double bonds; more preferably, it contains 1 unsaturated double bond.

[0076] R 7 and R 8 Examples of include, but are not limited to, nonadecyl, nonadecenyl, eicosyl, eicosenyl, heneicosyl, heneicosenyl, docosyl, docosenyl, tricosyl, tricosenyl. Preferably, R 7 and R 8 Each is independently selected from the group consisting of heneicosyl, heneicosenyl, docosyl, and docosenyl.

[0077] Examples of the third amide compound include, but are not limited to, stearyl erucic acid amide, oleyl palmitamide, ethylene bis erucic acid amide, ethylene bis oleic acid amide. Preferably, the third amide compound is selected from stearyl erucic acid amide, ethylene bis erucic acid amide, oleyl palmitamide.

[0078] The content of the third amide compound is 1 to 10 parts by weight, preferably 2 to 8 parts by weight, and more preferably 3 to 6 parts by weight.

[0079] Modified component B

[0080] The modified component B of the present invention includes fatty acid ester and boric acid ester. In some embodiments, the modified component B consists of fatty acid ester and boric acid ester. The volume ratio of fatty acid ester to boric acid ester is 1:(0.3-3); preferably 1:(0.5-2); more preferably 1:(1-1.5).

[0081] The fatty acid ester of the present invention is shown in formula (F):

[0082]

[0083] Among them, R 9is selected from a C8-C20 alkyl or alkenyl group, R 10 is selected from a C1 to C10 chain alkyl group. 9 is selected from a C10-C18 alkyl or alkenyl group. More preferably, R 9 is selected from a C11 to C17 alkyl or alkenyl group. 10 is selected from a C1 to C8 alkyl group. 10 A chain alkyl group selected from C1 to C3.

[0084] The alkyl group may be a straight chain alkyl group or a branched chain alkyl group. Preferably, the alkyl group is a branched chain alkyl group. The alkenyl group may be a straight chain alkenyl group or a branched chain alkenyl group. Preferably, the alkenyl group is a straight chain alkenyl group.

[0085] R 9 Examples of include, but are not limited to, undecyl, undecenyl, dodecyl, dodecenyl, tridecyl, tridecenyl, tetradecyl, tetradecenyl, pentadecyl, pentadecenyl, hexadecyl, hexadecenyl, heptadecyl, heptadecenyl. Preferably, R 9 Selected from heptadecyl, pentadecyl and undecyl.

[0086] R 10 Examples include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, neopentyl, hexyl, methylpentyl, dimethylbutyl, heptyl, methylhexyl, ethylpentyl, dimethylpentyl, octyl, isooctyl.

[0087] The fatty acid ester is liquid at 20-35°C; preferably, the fatty acid ester is liquid at 25-30°C.

[0088] Preferably, the fatty acid ester is selected from one or more of ethyl oleate, isooctyl oleate, methyl palmitate, and methyl laurate.

[0089] The boric acid ester of the present invention is shown in Formula G:

[0090]

[0091] Among them, R 11 ~R 13 are independently selected from C1 to C6 chain alkyl groups; preferably, are independently selected from C1 to C4 chain alkyl groups. 11 ~R 13 are the same group.

[0092] The borate ester is liquid at 20-35°C; preferably, the borate ester is liquid at 25-30°C.

[0093] R 11 ~R13 Examples 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.

[0094] Preferably, the borate ester is selected from one or more of tributyl borate, triethyl borate, and triisopropyl borate.

[0095] The modified component A and modified component B of the present invention are non-toxic and harmless, environmentally friendly, easy to remove at high temperatures, and have little impact on the magnetic properties of the magnet. The modified component A is mixed with the NdFeB alloy coarse powder during the jet milling process, and the modified component B is mixed with the NdFeB alloy fine powder. The two cooperate with each other to improve the fluidity and oxidation resistance of the magnetic powder. The modified magnetic powder is easy to be pressed into shape, improving the magnetic properties of the magnet such as coercivity, remanence, maximum magnetic energy product, and squareness.

[0096] <Preparation Method of NdFeB Magnetic Powder Composite Modifier>

[0097] The preparation method of the NdFeB magnetic powder composite modifier of the present invention includes the following steps: (A) preparation of the modified component A; and (B) preparation of the modified component B.

[0098] Preparation of modified component A

[0099] The present invention mixes the raw material A including the first amide compound, the second amide compound, and the third amide compound to obtain the modified component A. Preferably, the raw material A consists of the first amide compound, the second amide compound, and the third amide compound.

[0100] The selection and dosage of the first amide compound, the second amide compound, and the third amide compound are as described above, and will not be elaborated here. The mixing method can adopt the methods commonly used in the art, such as mechanical mixing. The mixing method is not limited herein.

[0101] Preparation of modified component B

[0102] The present invention mixes the raw material B including the fatty acid ester and the borate ester to obtain the modified component B. Preferably, the raw material B consists of the fatty acid ester and the borate ester.

[0103] The selection and dosage of the fatty acid ester and the borate ester are as described above, and will not be elaborated here. The mixing method can adopt the methods commonly used in the art, such as mechanical mixing. The mixing method is not limited herein.

[0104] <Use of NdFeB Magnetic Powder Composite Modifier>

[0105] The NdFeB magnetic powder composite modifier of the present invention can improve the magnetic properties of NdFeB magnets. Therefore, the present invention provides a use of a NdFeB magnetic powder composite 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.

[0106] <Method for preparing NdFeB magnet>

[0107] The method for producing NdFeB magnets of the present invention comprises the following steps: (1) a step of modifying coarse powder; (2) a step of modifying fine powder; and (3) a step of forming and heat treatment. In certain embodiments, the method further comprises the steps of smelting, rapid solidification stripping and hydrogen crushing.

[0108] The steps of melting, rapid solidification, strip throwing and hydrogen crushing

[0109] The present invention melts the raw materials to obtain a master alloy. The master alloy is subjected to a rapid solidification belt spinning process to obtain an alloy sheet. The alloy sheet is hydrogen crushed to obtain a coarse NdFeB alloy powder. The particle size of the coarse NdFeB alloy powder may range from 45 to 325 μm. Preferably, the raw materials are melted in a vacuum or inert atmosphere to obtain the master alloy. This can prevent the master alloy from being oxidized. The melting may be performed in a vacuum induction melting furnace.

[0110] Steps for coarse powder modification

[0111] In the present invention, the NdFeB alloy coarse powder and the modified component A are jet milled to obtain the NdFeB alloy fine powder. Preferably, the NdFeB alloy coarse powder and the modified component A are jet milled after initial mixing. The composition of the modified component A is as described above and will not be repeated here.

[0112] The amount of modified component A is 0.1-1 wt‰ of the NdFeB alloy coarse powder; preferably 0.3-0.8‰; more preferably 0.4-0.6‰.

[0113] The NdFeB alloy coarse powder includes Pr, Nd, Cu, Co, Al, Ga, Zr, B and Fe. In some embodiments, the NdFeB alloy coarse powder consists of Pr, Nd, Cu, Co, Al, Ga, Zr, B and Fe. Of course, the NdFeB alloy coarse powder may contain unavoidable impurities. For example, C, O, etc.

[0114] The total content of Pr and Nd can be 20 to 40 parts by weight; preferably 25 to 35 parts by weight; more preferably 30 to 31 parts by weight. The mass ratio of Pr to Nd can be 25:(50 to 90); preferably 25:(60 to 80); more preferably 25:(65 to 75). The content of Cu can be 0.01 to 0.55 parts by weight; preferably 0.05 to 0.3 parts by weight; more preferably 0.1 to 0.15 parts by weight. The content of Co can be 0.1 to 0.8 parts by weight; preferably 0.2 to 0.7 parts by weight; more preferably 0.3 to 0.5 parts by weight. The content of Al can be 0.2 to 0.9 parts by weight; preferably 0.3 to 0.8 parts by weight; more preferably 0.5 to 0.6 parts by weight. The content of Ga can be 0.03 to 0.6 parts by weight; preferably 0.1 to 0.5 parts by weight; more preferably 0.2 to 0.3 parts by weight. The content of Zr can be 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. The content of B can be 0.8 to 1.0 parts by weight, preferably 0.9 to 0.95 parts by weight. The content of Fe can be 60 to 80 parts by weight, preferably 63 to 75 parts by weight, and more preferably 65 to 70 parts by weight.

[0115] 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.

[0116] The jet milling can be carried out under an inert gas atmosphere. Examples of inert gases include, but are not limited to, N 2 , He, Ne, Ar or more. Preferably, the inert gas is N 2 The inert gas pressure may be 0.2 to 0.7 MPa, preferably 0.35 to 0.65 MPa, and more preferably 0.4 to 0.6 MPa.

[0117] During the jet milling process, O can be appropriately added to the inert gas. 2 .O 2 The content can be 5 to 25 ppm, preferably 10 to 20 ppm, which helps to improve cutting efficiency.

[0118] The repose angle of the NdFeB alloy fine powder is ≤50°; preferably, the repose angle is ≤45°; more preferably, the repose angle is ≤44°. In certain embodiments, the repose angle of the NdFeB alloy fine powder is ≤43°.

[0119] The tap density of NdFeB alloy fine powder can be 2-5 g / cm 3 ; preferably 3 to 4.5 g / cm 3 More preferably, 3.5 to 4 g / cm 3 .

[0120] Steps for fine powder modification

[0121] In the present invention, the modified NdFeB alloy powder is obtained by mixing the NdFeB alloy fine powder and the modified component B. The modified component B is as described above and will not be described again.

[0122] The amount of modified component B is 0.1-1 wt‰ of the NdFeB alloy fine powder; preferably 0.2-0.7 wt‰; more preferably 0.4-0.6 wt‰.

[0123] The mixing of the NdFeB alloy fine powder and the modified component B is preferably carried out under oxygen-free conditions. This can avoid the negative impact of oxygen on the 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.

[0124] The NdFeB alloy fine powder and the modified component B can be mixed at a speed of r 1 Mix under the conditions of r 2 Mix under the conditions of.

[0125] r 1 It may be 100 to 300 rpm, preferably 150 to 250 rpm, and more preferably 180 to 220 rpm.

[0126] In r 1 The mixing time under the rotation speed condition can be 3 to 25 min, preferably 5 to 20 min, and more preferably 10 to 15 min.

[0127] r 2 The speed may be 350 to 850 rpm, preferably 550 to 750 rpm, and more preferably 600 to 700 rpm.

[0128] In r 2 The mixing time under the rotation speed condition can be 5 to 40 minutes, preferably 10 to 30 minutes, and more preferably 15 to 25 minutes.

[0129] Forming and heat treatment steps

[0130] The invention forms modified NdFeB alloy powder and then performs heat treatment to obtain a neodymium iron boron magnet.

[0131] The modified NdFeB alloy powder is oriented and formed in a magnetic field to obtain a blank. Preferably, the blank is obtained without isostatic pressing after the oriented forming.

[0132] 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.

[0133] The molding pressure may be 2 to 16 MPa, preferably 10 to 14 MPa, and more preferably 12 to 13 MPa.

[0134] The holding time may be 0.5 to 10 seconds, preferably 1 to 5 seconds, and more preferably 2 to 3 seconds.

[0135] The density of the blank can be 2.0~6.0g / cm 3 ; preferably 3.5 to 5.5 g / cm 3 More preferably, 4 to 4.5 g / cm 3 .

[0136] The present invention heat treats the blank to obtain a NdFeB magnet. Preferably, the heat treatment includes sintering and aging treatment.

[0137] Sintering can be carried out under vacuum conditions, where vacuum means pressure ≤ 10 -2 Pa; preferably, pressure ≤10 -3 Pa. The blank can be subjected to three-stage sintering. Controlling the three-stage sintering at a specific temperature and time can reduce the impurity elements introduced by the modifier and improve the magnetic properties of the NdFeB magnet.

[0138] The primary sintering temperature may be 320-400° C. In some embodiments, the primary sintering temperature is 360-395° C. The primary sintering time may be 35-75 min; in some embodiments, the primary sintering time is 40-65 min.

[0139] The secondary sintering temperature may be 410-570° C. In some embodiments, the secondary sintering temperature is 460-520° C. The secondary sintering time may be 45-85 min. In some embodiments, the secondary sintering time is 50-70 min.

[0140] The tertiary sintering temperature may be 950-1250° C., preferably 1000-1100° C. The tertiary sintering time may be 2.5-7.5 hours, preferably 3-5 hours.

[0141] In the present invention, preferably, a secondary aging treatment is performed.

[0142] The primary aging temperature may be 700-1050° C., preferably 800-950° C., more preferably 850-950° C. The primary aging time may be 0.5-6 h, preferably 0.5-3 h, more preferably 0.5-1 h.

[0143] The secondary aging temperature may be 460-650° C., preferably 480-550° C. The secondary aging time may be 1-7 hours, preferably 3-6 hours.

[0144] The N content in the NdFeB magnet may be 260 to 680 ppm, preferably 290 to 600 ppm.

[0145] Here is the test method:

[0146] Magnetic properties of NdFeB magnets: The magnets were tested using a NIM-10000HC permanent magnet tester. The magnets were processed into cylinders with a diameter of 10 mm and a height of 10 mm using wire cutting, and the test temperature was 20°C. The test standard used was GB / T3217:2013.

[0147] Example 1

[0148] Modified component A was obtained by mixing 68.8 parts by weight of lauramide, 26.2 parts by weight of erucamide and 5.0 parts by weight of stearyl erucamide.

[0149] Ethyl oleate and triethyl borate were mixed in a volume ratio of 1:1 to obtain a modified component B.

[0150] Example 2

[0151] 74.2 parts by weight of hexadecanoic acid amide, 21.2 parts by weight of ethylenebislauric acid amide and 4.6 parts by weight of ethylenebiserucic acid amide were mixed to obtain a modified component A.

[0152] Isooctyl oleate and triisopropyl borate were mixed in a volume ratio of 1:1 to obtain a modified component B.

[0153] Example 3

[0154] 71.2 parts by weight of stearic acid amide, 24.2 parts by weight of behenic acid amide and 4.6 parts by weight of octadecyl erucic acid amide were mixed to obtain a modified component A.

[0155] Methyl palmitate and tributyl borate were mixed in a volume ratio of 1:1 to obtain a modified component B.

[0156] Example 4

[0157] Modified component A was obtained by mixing 68.5 parts by weight of oleic acid amide, 28.0 parts by weight of erucic acid amide and 3.5 parts by weight of oleyl palmitamide.

[0158] Methyl laurate and triethyl borate were mixed in a volume ratio of 1:1 to obtain a modified component B.

[0159] Embodiments 5 to 8

[0160] The raw materials 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 NdFeB alloy coarse powder with a particle size range of 45 to 325 μm. The composition of the NdFeB alloy coarse powder is as follows: the total content of Pr and Nd is 30.0 parts by weight (the mass ratio of Pr to Nd is 25:75); the content of Cu is 0.13 parts by weight; the content of Co is 0.4 parts by weight; the content of Al is 0.5 parts by weight; the content of Ga is 0.2 parts by weight; the content of Zr is 0.23 parts by weight; the content of B is 0.91 parts by weight; and the content of Fe is 67.63 parts by weight.

[0161] The NdFeB alloy coarse powder and the modified component A were premixed and then jet milled to obtain NdFeB alloy fine powder. The jet milling conditions were as follows: the classifier wheel speed was 4800 rpm; it was carried out under nitrogen and oxygen atmosphere, the air pressure was 0.46 MPa, and the initial oxygen content was 12 ppm. The selection and dosage of the modified component A and the physical properties of the NdFeB alloy fine powder are shown in Table 1.

[0162] Table 1

[0163]

[0164] The NdFeB alloy fine powder and the modified component B are mixed in O 2 Under the condition that the content is less than 50ppm, the mixture is first mixed at 200rpm for 10min and then at 600rpm for 20min to obtain modified NdFeB alloy powder. The selection and dosage of modified component B are shown in Table 2.

[0165] Table 2

[0166]

[0167] After the modified NdFeB alloy powder was oriented and formed in a magnetic field with a strength of 1.8T, a density of 4.2 to 4.32 g / cm was directly obtained. 3 The forming pressure is 13MPa and the holding time is 2s.

[0168] The blank is placed under a pressure of ≤10 -3 Under the condition of 25°C and 100°C, three-stage sintering is performed, and then air-cooling is performed to 25°C to obtain a sintered body. The sintered body is subjected to a secondary aging treatment, and then Ar with a temperature of 25°C and a purity of 99.99% is blown in and air-cooled to 25°C to obtain a NdFeB magnet. The sintering and aging treatment conditions are shown in Table 3, and the content of N element in the NdFeB magnet is shown in Table 3.

[0169] Table 3

[0170]

[0171] Comparative Example 1

[0172] Except that the modified component A is stearyl erucic acid amide, the rest is the same as Example 1. The repose angle and tap density of the NdFeB alloy fine powder and the magnetic properties of the NdFeB magnet are shown in Table 4.

[0173] Comparative Example 2

[0174] Except that the modified component B is ethyl oleate, the rest is the same as Example 1. The repose angle and tap density of the NdFeB alloy fine powder and the magnetic properties of the NdFeB magnet are shown in Table 4.

[0175] Table 4

[0176]

[0177] 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 NdFeB magnetic powder composite modifier, characterized in that: The NdFeB magnetic powder composite modifier comprises a modified component A and a modified component B; The modified component A comprises 60 to 85 parts by weight of a first amide compound, 15 to 35 parts by weight of a second amide compound and 1 to 10 parts by weight of a third amide compound; The first amide compound is represented by formula (A): Wherein, R1 is selected from C8-C19 alkyl or alkenyl; The second amide compound is represented by formula (B) or formula (C): Wherein, R2 is selected from a C20-C25 alkyl or alkenyl group; Wherein, R3 and R4 are independently selected from alkyl or alkenyl groups; the sum of the carbon atoms contained in R3 and R4 is 20 to 25; The third amide compound is represented by formula (D) or formula (E): Wherein, R5 and R6 are independently selected from alkyl or alkenyl groups; the sum of the carbon atoms contained in R5 and R6 is 30 to 43; Wherein, R7 and R8 are independently selected from alkyl or alkenyl groups; the sum of the carbon atoms contained in R7 and R8 is 30 to 43; The modified component B includes fatty acid ester and boric acid ester in a volume ratio of 1: (0.3-3).

2. The NdFeB magnetic powder composite modifier according to claim 1, characterized in that: The fatty acid ester is shown in formula (F): Wherein, R9 is selected from a C8-C20 alkyl or alkenyl group, R 10 Selected from C1-C10 chain alkyl groups.

3. The NdFeB magnetic powder composite modifier according to claim 1, characterized in that: The borate ester is shown in formula (G): Among them, R 11 ~R 13 Each is independently selected from C1 to C6 chain alkyl.

4. The NdFeB magnetic powder composite modifier according to claim 1, characterized in that: R1 is selected from C10-C18 alkyl or alkenyl, R2 is selected from C21-C23 alkyl or alkenyl, R3 and R4 are independently selected from C9-C13 alkyl or alkenyl, R5 is selected from C12-C23 alkyl or alkenyl, R6 is selected from C15-C19 alkyl or alkenyl, R7 and R8 are independently selected from C18-C24 alkyl or alkenyl.

5. The NdFeB magnetic powder composite modifier according to claim 2, characterized in that: R9 is selected from a C10-C18 alkyl or alkenyl group, R 10 A chain alkyl group selected from C1 to C8.

6. The NdFeB magnetic powder composite modifier according to claim 3, characterized in that: R 11 ~R 13 Same, R 11 ~R 13 Each is independently selected from C1 to C4 chain alkyl.

7. The method for preparing the NdFeB magnetic powder composite modifier according to any one of claims 1 to 6, characterized in that: The steps include: (A) mixing a raw material A comprising a first amide compound, a second amide compound and a third amide compound to obtain a modified component A; (B) Mixing raw material B including fatty acid ester and boric acid ester to obtain modified component B.

8. Use of the NdFeB magnetic powder composite modifier according to any one of claims 1 to 6 in improving the magnetic properties of NdFeB magnets.

9. The use of the NdFeB magnetic powder composite modifier according to claim 8, characterized in that: The magnetic properties are selected from one or more of remanence, coercive force, maximum magnetic energy product, and squareness; and the NdFeB magnet is a sintered NdFeB magnet.

10. A method for preparing a neodymium iron boron magnet, characterized in that: The steps include: (1) jet milling NdFeB alloy coarse powder and the modified component A in the NdFeB magnetic powder composite modifier according to any one of claims 1 to 6 to obtain NdFeB alloy fine powder; (2) mixing NdFeB alloy fine powder and the modified component B in the NdFeB magnetic powder composite modifier according to any one of claims 1 to 6 to obtain modified NdFeB alloy powder; (3) The modified NdFeB alloy powder is formed and then heat treated to obtain a NdFeB magnet.

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