Multifunctional cutting fluid for neodymium-cerium-iron-boron magnet and preparation method thereof

Abstract

The application discloses a multifunctional cutting fluid for neodymium-cerium-iron-boron magnets, which is composed of the following components with mass percentages: 3-15% of monocarboxylic acid, 1-7% of dicarboxylic acid, 16-25% of organic amine, 8-15% of polyether, 1-4% of corrosion inhibitor, 0.2-1% of wetting agent, 0.2-1% of settling agent, 0.5-1.5% of bactericide, 0.01-0.1% of defoaming agent, and the balance of water; the mass ratio of the monocarboxylic acid to the dicarboxylic acid is 1: (0.9-1.2). Compared with the prior art, the cutting fluid has excellent cooling, cleaning, settling, primer compatibility and lubricating properties, and has good corrosion resistance and compatibility with various metals such as aluminum and copper, effectively solves the problems of poor corrosion resistance, insufficient lubrication and poor multi-metal compatibility of the existing market cutting fluid and conventional neodymium-iron-boron cutting fluid, and is especially suitable for the precision machining field of neodymium-cerium-iron-boron magnets.

Description

Invention Field

[0001] This invention belongs to the field of magnetic metal processing, specifically relating to a multifunctional cutting fluid for neodymium-cerium-iron-boron magnets and its preparation method. Background Technology

[0002] Neodymium iron boron (NdFeB) magnets are widely used in wind power generation, new energy vehicles, and consumer electronics due to their excellent magnetic properties (such as high remanence, high coercivity, and maximum energy product), serving as core materials for drive motors and sensors. However, traditional NdFeB magnets contain a large amount of the rare-earth metal neodymium, resulting in high production costs and over-reliance on neodymium resources. To alleviate this contradiction, NdFeB magnet materials, which use high-abundance cerium (Ce) to replace part of the neodymium, have been developed in recent years. The introduction of cerium not only effectively reduces raw material costs but also achieves balanced utilization of rare-earth resources, becoming an important research direction in the field of permanent magnet materials.

[0003] However, the cerium element in NdFeB also brings new problems. Cerium is more reactive than praseodymium, making NdFeB materials more susceptible to oxidation and corrosion than traditional NdFeB, with more complex corrosion behavior, especially in harsh environments such as humid conditions. The addition of cerium leads to the formation of the CeFe2 phase, which disrupts the wetting and coupling effect of the grain boundaries on the main phase grains. The continuity and uniformity of the grain boundary phase decrease, making it prone to defects such as edge chipping, cracking, and corner breakage during processing, requiring stronger lubrication performance.

[0004] Currently, in practical applications, cutting oils primarily composed of mineral oil and fatty oil are commonly used in the machining of NdFeB materials. While these cutting oils offer good lubrication, they suffer from poor cooling, cleaning, and chip settling properties. During high-speed machining, they easily generate large amounts of oil mist, polluting the work environment, harming operator health, and increasing subsequent cleaning difficulty and production costs. In recent years, water-based cutting fluids have gradually become the mainstream alternative to traditional cutting oils. Conventional NdFeB cutting fluids must meet basic requirements such as lubrication, rust and corrosion prevention, chip settling, and non-damage to the underlying adhesive.

[0005] The machining requirements for neodymium cerium iron boron (NdFeB) permanent magnets are basically the same as those for NdFeB magnets. However, due to the introduction of cerium into the material, NdFeB magnets have higher chemical activity and lower mechanical toughness compared to conventional NdFeB magnets. This results in higher brittleness, greater susceptibility to corrosion, and a higher likelihood of chipping and breakage during machining. Therefore, higher requirements are placed on the lubrication and corrosion protection performance of the cutting fluid. Furthermore, in actual machining operations, components such as the guide rail system, fluid tank, worktable, carrier, and protective cover of the machining equipment are often made of multiple metals, including copper and aluminum. The magnet workpiece and these dissimilar metal components are in long-term contact under the cutting fluid environment, which can easily lead to contact corrosion.

[0006] Most commercially available cutting fluids and conventional NdFeB cutting fluids are designed only for conventional NdFeB materials and general machining environments. They can only achieve basic functions such as cooling, cleaning, settling, primer protection, and general lubrication and rust prevention. They are not optimized for the high activity and brittleness of NdFeB, and cannot meet its higher-level lubrication and rust prevention requirements. Furthermore, they do not consider the complex working conditions where multiple metals such as copper and aluminum coexist in the machining system, and lack the ability to inhibit multi-metal contact corrosion. This can easily lead to rust on the magnet workpiece, reduced machining accuracy, and corrosion damage to the metal parts of the equipment, making it difficult to meet the long-term stable service requirements for precision machining of NdFeB permanent magnets.

[0007] Therefore, developing a multifunctional cutting fluid for neodymium-cerium-iron-boron magnets, which combines excellent cooling, cleaning and settling properties, and compatibility with primers, while also providing good lubrication and corrosion resistance to various metals such as aluminum and copper, is of great practical significance for promoting the upgrading of rare earth permanent magnet material processing technology. Summary of the Invention

[0008] The purpose of this invention is to provide a multifunctional cutting fluid for neodymium cerium iron boron magnets, in order to solve the problems of poor corrosion resistance, insufficient lubrication and poor multi-metal compatibility of existing commercially available cutting fluids and conventional neodymium iron boron cutting fluids.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A multifunctional cutting fluid for neodymium cerium iron boron magnets, comprising, by weight 100%, the following components in the indicated mass percentages: 3-15% monocarboxylic acid, 1-7% dicarboxylic acid, 16-25% organic amine, 8-15% polyether, 1-4% corrosion inhibitor, 0.2-1% wetting agent, 0.2-1% settling agent, 0.5-1.5% bactericide, 0.01-0.1% defoamer, with the balance being water;

[0011] The mass ratio of the monocarboxylic acid to the dicarboxylic acid is 1:(0.9-1.2).

[0012] The monocarboxylic acid is any one or a combination of two or more monocarboxylic acids with carbon atoms from C8 to C18 in any proportion; preferably, it is a combination of one or more monocarboxylic acids, such as octanoic acid, isooctanoic acid, nonanoic acid, isononanoic acid, neodecanoic acid, or isodecanic acid in any proportion.

[0013] The dicarboxylic acid is any one or more of the dicarboxylic acids with carbon atoms C9-C22, in any proportion; preferably, it is a combination of one or more of the dicarboxylic acids, such as azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, or icosanoic acid, in any proportion.

[0014] The corrosion inhibitor is a composition of at least two of benzotriazole, methylbenzotriazole, fatty acid polyethylene glycol ether phosphate, isomeric alcohol phosphate, phenolic phosphate, or octylphosphonic acid in any proportion. Preferably, it is a composition of at least two of benzotriazole, methylbenzotriazole, isomeric alcohol phosphate, or octylphosphonic acid in any proportion.

[0015] Further, the organic amine is one or more of monoethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, monoisopropanolamine, dihydroxyethylcyclohexylamine, alkylated dihydroxyethylcyclohexylamine, 2-amino-2-methyl-1-propanol, diethylene glycolamine, or dicyclohexylamine in any proportion. More preferably, it is one or more of monoethanolamine, diethanolamine, triethanolamine, dihydroxyethylcyclohexylamine, 2-amino-2-methyl-1-propanol, or diethylene glycolamine in any proportion.

[0016] Furthermore, the polyether is a propylene glycol block polyether or a trans polyether, or a combination of both in any proportion. Commercially available propylene glycol block polyethers include: propylene glycol block polyether L61, propylene glycol block polyether L62, propylene glycol block polyether L63, etc., and commercially available trans polyethers include: trans polyether 1720, trans polyether 1740, etc.

[0017] Furthermore, the wetting agent is any one or a combination of two or more of the following: acetylenic diol wetting agents, polyether wetting agents, and polyoxyethylene ether wetting agents, in any proportion.

[0018] Furthermore, the settling agent is a polyquaternary ammonium salt compound, such as commercially available Buckman Busan 77, Dexu DX309, Solvay WT, etc.

[0019] Furthermore, the bactericide is any one or a combination of two or more of N,N-methylenebismorpholine, 1,3,5-tris(2-hydroxyethyl)-hexahydro-triazine, 1,2-benzisothiazol-3-one, 2-butyl-1,2-benzisothiazol-3-one, and 3-iodo-2-propynyl butylcarbamate in any proportion.

[0020] Furthermore, the defoamer is any one or a combination of two or more of the following in any proportion: silicone defoamer (such as AFE1267 from Dow Chemical Company), polyether defoamer (such as DF104 from Dow Chemical Company), and modified alcohol defoamer (such as Surfynol485 from Evonik Specialty Chemicals (Shanghai) Co., Ltd.).

[0021] The preparation method of the above-mentioned multifunctional cutting fluid for neodymium cerium iron boron magnets is as follows: add monocarboxylic acid, dicarboxylic acid, organic amine and corrosion inhibitor to water, stir evenly, then add polyether, wetting agent, flocculant and bactericide in sequence, stir evenly, and finally add defoamer and stir evenly to obtain the fluid.

[0022] The above-mentioned multifunctional cutting fluid is used in the cutting or wire EDM of neodymium cerium iron boron magnets.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The cutting fluid of the present invention has excellent cooling, cleaning and settling properties and compatibility with primer, while also having good lubrication and good anti-corrosion compatibility with various metals such as aluminum and copper.

[0025] (2) This invention achieves a synergistic balance between lubrication performance and Nd:cerium-iron-boron (Nd:C) corrosion inhibition by combining a monocarboxylic acid with a specific carbon chain and a dicarboxylic acid. The monocarboxylic acid, through its long-chain alkyl structure, forms a lubricating film at the cutting interface, effectively reducing friction and cutting heat. The dicarboxylic acid, utilizing its dicarboxyl structure, selectively chelates and adsorbs with the active cerium ions in the Nd:C magnet, forming a dense cerium-carboxylic acid complex protective layer in situ on the magnet surface, significantly inhibiting selective cerium corrosion. The monocarboxylic acid and dicarboxylic acid form a complementary dual function of "lubrication-film formation," avoiding the shortcomings of poor water solubility of single long-chain fatty acids and insufficient lubrication of single dicarboxylic acids, while fully utilizing the advantages of fast reaction and uniform film formation of medium-chain carboxylic acids, making it particularly suitable for the precision machining of Nd:C magnets.

[0026] (3) This invention introduces a multi-element corrosion inhibitor system. Through the competitive adsorption and synergistic film formation of different corrosion inhibitor molecules on the metal surface, it achieves simultaneous protection of various metal materials such as neodymium cerium iron boron magnets and copper and aluminum alloy components in cutting equipment. The multi-element corrosion inhibitors form a composite adsorption layer through intermolecular interactions, overcoming the limitations of a single corrosion inhibitor. This allows the cutting fluid to maintain stable anti-rust performance during long-term cyclic use, avoiding a decrease in machining accuracy and cutting fluid contamination caused by equipment corrosion.

[0027] (4) This invention solves the problem of powder accumulation in NdFeB cutting by combining wetting agent and settling agent through the two continuous processes of dispersion and settling, thus avoiding the industry problem of wire breakage caused by accumulation. The synergistic effect of wetting and settling effectively reduces the frictional resistance of the cutting wire and improves the continuous running time and workpiece accuracy of multi-wire cutting. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments.

[0029] Example 1

[0030] A multifunctional cutting fluid for neodymium-cerium-iron-boron magnets comprises the following components: 55.6g water, 6g monocarboxylic acid (composed of 1g octanoic acid and 5g nonanoic acid), 6g dicarboxylic acid (composed of 3g sebacic acid and 3g undecanoic acid), 20g organic amine (composed of 15g triethanolamine and 5g 2-amino-2-methyl-1-propanol), 2g corrosion inhibitor (composed of 1g benzotriazole and 1g isotridecyl phosphate), 8g polyether (composed of 4g propylene glycol block polyether L62 and 4g trans polyether 1740), 0.5g wetting agent (composed of 0.3g acetylenic diol wetting agent and 0.2g polyether wetting agent), 0.3g settling agent (Bachmann Busan 77), and 1.5g bactericide (composed of 1g N,N-methylenebismorpholine and 0.5g... Composed of 1,3,5-tris(2-hydroxyethyl)-hexahydro-triazine), 0.1g defoamer (composed of 0.05g silicone defoamer AFE1267 and 0.05g polyether defoamer DF104).

[0031] The preparation method of the multifunctional cutting fluid for Nd: 1) Monocarboxylic acid, dicarboxylic acid, organic amine and corrosion inhibitor are added to water and stirred evenly at room temperature. Then, polyether, wetting agent, flocculant and bactericide are added in sequence and stirred evenly at room temperature. Finally, defoamer is added and stirred evenly to obtain a uniform and transparent liquid, which is the multifunctional cutting fluid for Nd: cerium iron boron magnets.

[0032] Example 2

[0033] A multifunctional cutting fluid for neodymium-cerium-iron-boron magnets comprises the following components: 54.6g water, 4g monocarboxylic acid (octanoic acid), 4.5g dicarboxylic acid (undecanoic acid), 22g organic amine (2-amino-2-methyl-1-propanol), 3g corrosion inhibitor (composed of 2g benzotriazole and 1g octylphosphonic acid), 10g polyether (propylene glycol block polyether L62), 0.3g wetting agent (acetylenic diol wetting agent), 0.5g settling agent (composed of 0.1g Buckman Busan 77 and 0.4g Dexu DX309), 1g bactericide (1,2-benzisothiazol-3-one), and 0.1g defoamer (modified alcohol defoamer Surfynol 485).

[0034] The preparation steps for the multifunctional cutting fluid for neodymium-cerium-iron-boron magnets are the same as in Example 1.

[0035] Example 3

[0036] A multifunctional cutting fluid for neodymium-cerium-iron-boron magnets comprises the following components: 51.82g water, 7g monocarboxylic acid (neodecanonical acid), 6.5g dicarboxylic acid (docosahexacarboxylic acid), 17g organic amine (composed of 2g triethanolamine and 15g diethylene glycolamine), 2.5g corrosion inhibitor (composed of 2g octylphosphonic acid and 0.5g isotridecyl phosphate), 12g polyether (trans-polyether 1740), 0.8g wetting agent (polyether wetting agent), 0.8g settling agent (Dexu DX309), 1.5g bactericide (N,N-methylenebismorpholine), and 0.08g defoamer (organosilicon defoamer AFE1267).

[0037] The preparation steps for the multifunctional cutting fluid for neodymium-cerium-iron-boron magnets are the same as in Example 1.

[0038] Comparative Example 1

[0039] A multifunctional cutting fluid for neodymium-cerium-iron-boron magnets comprises the following components: 51.82g water, 13.5g dicarboxylic acid (docosahexacarboxylic acid), 17g organic amine (composed of 2g triethanolamine and 15g diethylene glycolamine), 2.5g corrosion inhibitor (composed of 2g octylphosphonic acid and 0.5g isotridecyl phosphate), 12g polyether (trans polyether 1740), 0.8g wetting agent (polyether wetting agent), 0.8g settling agent (Dexu DX309), 1.5g bactericide (N,N-methylenebismorpholine), and 0.08g defoamer (organosilicon defoamer AFE1267).

[0040] Except for the absence of monocarboxylic acid, the preparation steps of the Nd:C:FeB magnet using the multifunctional cutting fluid are the same as in Example 1.

[0041] Comparative Example 2

[0042] A multifunctional cutting fluid for neodymium-cerium-iron-boron magnets comprises the following components: 51.82g water, 13.5g monocarboxylic acid (neodecanonical acid), 17g organic amine (composed of 2g triethanolamine and 15g diethylene glycolamine), 2.5g corrosion inhibitor (composed of 2g octylphosphonic acid and 0.5g isotridecyl phosphate), 12g polyether (trans-polyether 1740), 0.8g wetting agent (polyether wetting agent), 0.8g settling agent (Dexu DX309), 1.5g bactericide (N,N-methylenebismorpholine), and 0.08g defoamer (organosilicone defoamer AFE1267).

[0043] Except for the absence of dicarboxylic acid, the preparation steps of the Nd:cerium-iron-boron magnet multifunctional cutting fluid are the same as in Example 1.

[0044] Comparative Example 3

[0045] A multifunctional cutting fluid for neodymium-cerium-iron-boron magnets comprises the following components: 51.82g water, 1g monocarboxylic acid (neodecanonical acid), 12.5g dicarboxylic acid (docosahexacarboxylic acid), 17g organic amine (composed of 2g triethanolamine and 15g diethylene glycolamine), 2.5g corrosion inhibitor (composed of 2g octylphosphonic acid and 0.5g isotridecyl phosphate), 12g polyether (trans-polyether 1740), 0.8g wetting agent (polyether wetting agent), 0.8g settling agent (Dexu DX309), 1.5g bactericide (N,N-methylenebismorpholine), and 0.08g defoamer (organosilicon defoamer AFE1267).

[0046] The preparation steps for the multifunctional cutting fluid for neodymium-cerium-iron-boron magnets are the same as in Example 1.

[0047] Comparative Example 4

[0048] A multifunctional cutting fluid for neodymium-cerium-iron-boron magnets comprises the following components: 51.82g water, 12.5g monocarboxylic acid (neodecanonical acid), 1g dicarboxylic acid (docosahexacarboxylic acid), 17g organic amine (composed of 2g triethanolamine and 15g diethylene glycolamine), 2.5g corrosion inhibitor (composed of 2g octylphosphonic acid and 0.5g isotridecyl phosphate), 12g polyether (trans-polyether 1740), 0.8g wetting agent (polyether wetting agent), 0.8g settling agent (Dexu DX309), 1.5g bactericide (N,N-methylenebismorpholine), and 0.08g defoamer (organosilicon defoamer AFE1267).

[0049] The preparation steps for the multifunctional cutting fluid for neodymium-cerium-iron-boron magnets are the same as in Example 1.

[0050] Comparative Example 5

[0051] A multifunctional cutting fluid for neodymium-cerium-iron-boron magnets comprises the following components: 51.82g water, 7g monocarboxylic acid (neodecanonical acid), 6.5g dicarboxylic acid (docosahexacarboxylic acid), 17g organic amine (composed of 2g triethanolamine and 15g diethylene glycolamine), 2.5g corrosion inhibitor (isotridecyl phosphate), 12g polyether (trans-polyether 1740), 0.8g wetting agent (polyether wetting agent), 0.8g settling agent (Dexu DX309), 1.5g bactericide (N,N-methylenebismorpholine), and 0.08g defoamer (organosilicon defoamer AFE1267).

[0052] The preparation steps for the multifunctional cutting fluid for neodymium-cerium-iron-boron magnets are the same as in Example 1.

[0053] Comparative Example 6

[0054] A multifunctional cutting fluid for neodymium-cerium-iron-boron magnets comprises the following components: 51.82g water, 7g monocarboxylic acid (neodecanonical acid), 6.5g dicarboxylic acid (docosahexacarboxylic acid), 17g organic amine (composed of 2g triethanolamine and 15g diethylene glycolamine), 2.5g corrosion inhibitor (composed of 2g octylphosphonic acid and 0.5g isotridecyl phosphate), 12g polyether (trans-polyether 1740), 1.6g wetting agent (polyether wetting agent), 1.5g bactericide (N,N-methylenebismorpholine), and 0.08g defoamer (organosilicon defoamer AFE1267).

[0055] Except for the absence of a settling agent, the preparation steps for the multifunctional cutting fluid for the Nd:C:FeB magnet are the same as in Example 1.

[0056] The multifunctional cutting fluids for NdFeB magnets prepared in Examples 1-3 and Comparative Examples 1-6, as well as commercially available NdFeB cutting fluids, were tested for pH, surface tension, sedimentation performance, defoaming performance, corrosion resistance (copper, LY12 aluminum), corrosion resistance (NdFeB), and lubrication performance. The test methods for each index are as follows:

[0057] pH: Dilute the cutting fluid sample with water to a concentration of 3% by mass, and then measure the pH value of the diluted solution.

[0058] Surface tension: The cutting fluid sample was diluted with water to a mass concentration of 3%, and the surface tension of the diluted solution was tested according to GB / T 6144-2010 "Synthetic Cutting Fluids".

[0059] Sedimentation performance: Dilute the cutting fluid sample with water to a mass concentration of 3%. Take 80g of the diluted solution and place it in a 100mL stoppered graduated cylinder. Add 1g of neodymium cerium iron boron powder (400 mesh, provided by Taizhou Yibang Magnetic Materials Co., Ltd.). After stopping the cylinder, shake it up and down at a frequency of 100 times / min for 1min with a shaking amplitude of 0.3m. After shaking, let it stand and start timing. Record the time required for the metal powder to show no obvious suspension.

[0060] Defoaming performance: The cutting fluid sample was diluted with water to a concentration of 3% by mass, and the defoaming performance of the diluted solution was tested according to GB / T 6144-2010 "Synthetic Cutting Fluids".

[0061] Corrosion resistance (copper, LY12 aluminum): The cutting fluid sample was diluted with water to a mass concentration of 3%. According to GB / T 6144-2010 "Synthetic Cutting Fluids", the corrosion resistance of the diluted solution to copper and LY12 aluminum was tested.

[0062] Corrosion resistance (NdFeB): Dilute the cutting fluid sample with water to a concentration of 3% by mass. Immerse NdFeB test pieces (test piece size: 25mm×50mm×3mm, provided by Taizhou Yibang Magnetic Materials Co., Ltd.) completely in the solution. Cover with a glass cover and place in a constant temperature chamber at 55℃±2℃. Conduct the test continuously for 4 hours. After the test, remove the test pieces for inspection: if there is no rust and the gloss is like new, it is judged as Grade A; if there is no rust but slight loss of gloss, it is judged as Grade B; if there is slight corrosion or slight loss of gloss, it is judged as Grade C; if there is severe corrosion or severe loss of gloss, it is judged as Grade D.

[0063] Lubrication performance: The cutting fluid sample was diluted with water to a mass concentration of 3%. According to GB / T 3142-2019 Determination of load-carrying capacity of lubricants - four-ball method, the maximum non-seize load (PB) and sintering load (PD) of the diluted solution were tested.

[0064] The performance test results are shown in Table 1:

[0065] Table 1 Performance Test Results

[0066]

[0067] As can be seen from the test results in Table 1, compared with commercially available NdFeB cutting fluids, the cutting fluids of Examples 1-3 of this invention all have better cleaning and settling properties, and better corrosion resistance to NdFeB materials, aluminum, and copper, effectively solving problems such as edge chipping and cracking during the processing of NdFeB materials. Although the cutting fluid of Comparative Example 6 has excellent corrosion resistance to NdFeB materials, aluminum, and copper, its cleaning and settling properties are poor, affecting its use in the processing of NdFeB materials. Although the cutting fluids of Comparative Examples 1-5 and commercially available NdFeB cutting fluids have good cleaning and settling properties, their corrosion resistance compatibility with NdFeB materials, aluminum, and copper is poor.

[0068] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A multifunctional cutting fluid for neodymium-cerium-iron-boron magnets, characterized in that, Based on the total mass of the cutting fluid (100%), the cutting fluid is composed of the following components in the following mass percentages: 3-15% monocarboxylic acid, 1-7% dicarboxylic acid, 16-25% organic amine, 8-15% polyether, 1-4% corrosion inhibitor, 0.2-1% wetting agent, 0.2-1% settling agent, 0.5-1.5% bactericide, 0.01-0.1% defoamer, with the balance being water; The mass ratio of the monocarboxylic acid to the dicarboxylic acid is 1:(0.9-1.2). The monocarboxylic acid is any one or a combination of two or more monocarboxylic acids with carbon atoms from C8 to C18 in any proportion; The dicarboxylic acid is any one or a combination of two or more dicarboxylic acids with carbon atoms C9-C22 in any proportion; The corrosion inhibitor is a combination of at least two of the following in any proportion: benzotriazole, methylbenzotriazole, fatty acid polyethylene glycol ether phosphate, isomeric alcohol phosphate, phenolic phosphate, or octylphosphonic acid.

2. The multifunctional cutting fluid for neodymium-cerium-iron-boron magnets as described in claim 1, characterized in that, The monocarboxylic acid is one or more of the following: octanoic acid, isooctanoic acid, nonanoic acid, isononanoic acid, neodecanoic acid, or isodecanic acid, in any proportion.

3. The multifunctional cutting fluid for neodymium-cerium-iron-boron magnets as described in claim 1, characterized in that, The dicarboxylic acid is one or more of azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, or icosanoic acid in any proportion.

4. The multifunctional cutting fluid for neodymium-cerium-iron-boron magnets as described in claim 1, characterized in that, The corrosion inhibitor is a combination of at least two of benzotriazole, methylbenzotriazole, isomeric alcohol phosphate, or octylphosphonic acid in any proportion.

5. The multifunctional cutting fluid for neodymium-cerium-iron-boron magnets as described in claim 1, characterized in that, The organic amine is one or more of monoethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, monoisopropanolamine, dihydroxyethylcyclohexylamine, alkylated dihydroxyethylcyclohexylamine, 2-amino-2-methyl-1-propanol, diethylene glycolamine, or dicyclohexylamine, in any proportion.

6. The multifunctional cutting fluid for neodymium-cerium-iron-boron magnets as described in claim 1, characterized in that, The polyether is a propylene glycol block polyether or a trans polyether or a combination of the two in any proportion.

7. The multifunctional cutting fluid for neodymium-cerium-iron-boron magnets as described in claim 1, characterized in that, The wetting agent is any one or a combination of two or more of the following: acetylenic diol wetting agents, polyether wetting agents, and polyoxyethylene ether wetting agents, in any proportion.

8. The multifunctional cutting fluid for neodymium-cerium-iron-boron magnets as described in claim 1, characterized in that, The settling agent is a polyquaternary ammonium salt compound.

9. The multifunctional cutting fluid for neodymium-cerium-iron-boron magnets as described in any one of claims 1 to 8, characterized in that, The bactericide is any one or a combination of two or more of N,N-methylenebismorpholine, 1,3,5-tris(2-hydroxyethyl)-hexahydro-triazine, 1,2-benzisothiazol-3-one, 2-butyl-1,2-benzisothiazol-3-one, and 3-iodo-2-propynyl butylcarbamate in any proportion.

10. A method for preparing the multifunctional cutting fluid for neodymium-cerium-iron-boron magnets according to any one of claims 1 to 9, characterized in that, Add monocarboxylic acid, dicarboxylic acid, organic amine and corrosion inhibitor to water, stir well, then add polyether, wetting agent, flocculant and bactericide in sequence, stir well, and finally add defoamer and stir well to obtain the product.

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