Long-acting environment-friendly all-synthetic cutting fluid for aluminum-magnesium alloy and preparation method thereof

Abstract

This invention discloses a long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys and its preparation method. The cutting fluid comprises 5-15% binary composite polyether lubricant, 0.5-3% nanoparticle additives, 2-8% isooctanol polyoxyethylene ether phosphate, 0.5-2% tannic acid, 2-8% surfactant, 5-15% pH stabilizer, 1-5% corrosion inhibitor, 0.5-2% bactericide, 0.1-1% defoamer, and deionized water. Through the synergistic effect of the compounded lubrication system and nanoparticle additives, this cutting fluid significantly improves lubrication, cooling, and corrosion resistance. It exhibits excellent lubrication, friction reduction, and cooling properties, with an average friction coefficient < 0.073 and a maximum cutting tip temperature ≤ 100℃. It also demonstrates strong corrosion resistance; after immersion at 50℃ for 15 days, the alloy surface shows no change, and the pH remains stable with low bacterial counts during 6 months of use. It can be used for cutting and grinding aluminum-magnesium alloys, achieving long-term operation without the need for fluid changes, and meets environmental protection requirements.

Description

A long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys and its preparation method. Technical Field

[0001] This invention relates to the field of metalworking fluid technology, specifically to a fully synthetic cutting fluid for machining aluminum, magnesium and their alloys, and its preparation method. Background Technology

[0002] Aluminum-magnesium alloys are widely used in aerospace, automotive manufacturing, and electronics industries due to their advantages such as light weight, high strength, good thermal conductivity, and strong electromagnetic shielding capabilities. However, aluminum-magnesium alloys, especially magnesium alloys, are chemically highly reactive, posing numerous challenges during machining. First, if the large amount of cutting heat generated during machining cannot be dissipated in time, it will accelerate tool wear, affecting the dimensional accuracy and surface quality of the workpiece. Second, magnesium alloys are highly susceptible to electrochemical corrosion in humid and hot environments, easily resulting in black spots, white spots, or oxide layers on the workpiece surface after machining, severely affecting the product's appearance and performance. Traditional cutting fluids are mainly classified into oil-based cutting fluids, emulsions, semi-synthetic cutting fluids, and fully synthetic cutting fluids. However, existing aluminum-magnesium alloy cutting fluids mainly suffer from the following problems:

[0003] Corrosion is a significant issue: While traditional oil-based cutting fluids offer good lubrication, they suffer from poor cooling performance, and the oil mist is harmful to the environment and operator health. More importantly, to improve the performance of water-based cutting fluids, amines are often added to adjust pH and prevent rust; however, some amines can cause corrosion or discoloration of chemically reactive aluminum-magnesium alloys. Furthermore, extreme pressure additives such as chlorine and sulfur in some cutting fluid formulations may also react with aluminum-magnesium alloys at high temperatures, initiating corrosion.

[0004] Short service life and difficult waste liquid treatment: Emulsions and semi-synthetic cutting fluids contain mineral oil, which easily breeds bacteria and mold, causing the cutting fluid to smell bad, degrade in performance, and require frequent replacement. Their typical service life is only a few months. This not only increases production costs, but also generates a large amount of complex waste liquid that is difficult and costly to treat, contradicting increasingly stringent environmental regulations.

[0005] Performance is difficult to balance: While traditional fully synthetic cutting fluids offer excellent cooling and cleaning properties and good biological stability, their lubrication performance is generally poor, making it difficult to meet the high-gloss machining requirements of soft metals such as aluminum and magnesium alloys. Some additives added to improve lubrication may sacrifice corrosion resistance or stability.

[0006] "Zero emissions" are difficult to achieve: While the market has the concept of "zero emissions," it mostly refers to filtering, purifying, and reusing waste fluid through complex back-end treatment equipment, rather than the inherent long-term stability of the cutting fluid itself. Existing technologies rarely offer a solution designed from the source of the formulation that achieves "no fluid change required" through ultra-high stability and biological resistance, thereby fundamentally reducing waste fluid emissions.

[0007] Therefore, developing a fully synthetic cutting fluid that can provide excellent lubrication and cooling for aluminum-magnesium alloys, effectively inhibit their corrosion, and possess ultra-long-term stability and environmental friendliness, enabling long-term use without replacement and achieving "zero emissions," is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys that has good lubricity, strong cooling, does not corrode aluminum-magnesium alloys, has a long service life, and its preparation method.

[0009] This invention provides a long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys. The cutting fluid comprises the following components by mass percentage: 5-15% binary composite polyether lubricant, 0.5-3% nanoparticle additive, 2-8% isooctanol polyoxyethylene ether phosphate, 0.5-2% tannic acid, 2-8% surfactant, 5-15% pH stabilizer, 1-5% corrosion inhibitor, 0.5-2% bactericide, 0.1-1% defoamer, and the balance being deionized water.

[0010] Preferably, the binary composite polyether lubricant is composed of polypropylene glycol monobutyl ether and polyoxyethylene-polyoxypropylene copolymer mixed in a mass ratio of 1-3:1.

[0011] Preferably, the preparation method of the nanoparticle additive includes the following steps:

[0012] Nano-magnesium aluminum hydrotalcite and nano-silica were dispersed in an ethanol solution, and then triethanolamine oleate was slowly added and stirred. After centrifugation, the solid was collected and washed to obtain nanoparticle additives.

[0013] Preferably, the ethanol solution is a 70-90% aqueous ethanol solution.

[0014] Preferably, the nano-magnesium aluminum hydrotalcite has a particle size of 50-100 nm, the nano-silica has a particle size of 10-30 nm, and the mass ratio of the nano-magnesium aluminum hydrotalcite, nano-silica, and triethanolamine oleate is 5-10:1-3:1.

[0015] Preferably, the temperature of the stirring reaction is 20-50℃, and the stirring reaction time is 1-3h.

[0016] Preferably, the pH stabilizer comprises at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium tetraborate, tris(hydroxymethyl)aminomethane, and diethanolamine.

[0017] Preferably, the surfactant comprises at least one of fatty acid polyoxyethylene ether, castor oil polyoxyethylene ether, hexadecyltrimethylammonium chloride, sodium dodecyl sulfate, or sodium dodecylbenzene sulfonate.

[0018] Preferably, the corrosion inhibitor comprises at least one selected from methylbenzotriazole, sodium mercaptobenzothiazole, sodium benzoate, sodium molybdate, sodium fluorosilicate, and trisodium phosphate. More preferably, the corrosion inhibitor is a mixture of methylbenzotriazole and sodium mercaptobenzothiazole in a mass ratio of 3:1. Methylbenzotriazole is a highly efficient aluminum corrosion inhibitor, while mercaptobenzothiazole has good protective effects on magnesium and other non-ferrous metals; the combination of the two provides synergistic protection for aluminum-magnesium alloys.

[0019] Preferably, the defoamer includes at least one of polyether-modified silicone oil defoamers and polyether-type defoamers. For example, AFE-1267, AFE-3168, and AFE-0120 polyether-modified silicone oil defoamers produced by Dow Chemical, or TERGITOL L-61 polyether defoamer produced by Dow Chemical, with AFE-1267 defoamer being more preferred.

[0020] Preferably, the bactericide includes at least one of 1,2-benzisothiazolin-3-one and polyhexamethylene guanidine. More preferably, the bactericide is a mixture of 1,2-benzisothiazolin-3-one (BIT) and polyhexamethylene guanidine (PHMG) in a 1:1 ratio.

[0021] The present invention provides a method for preparing a long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys as described above, comprising the following steps: stirring and mixing each component evenly to obtain the long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys.

[0022] Preferably, the mixing temperature is 30-50℃ and the mixing time is 1-5h.

[0023] This invention provides the application of the long-lasting environmentally friendly fully synthetic cutting fluid described in the above scheme or the long-lasting environmentally friendly fully synthetic cutting fluid prepared by the above scheme in the cutting or grinding of magnesium-aluminum alloys.

[0024] The binary composite polyether lubricant of this invention is formulated from polypropylene glycol monobutyl ether and polyoxyethylene-polyoxypropylene copolymer in a mass ratio of (1–3):1. It possesses excellent water solubility, lubricity, and thermal stability, forming a strong and tough lubricating film on metal surfaces, significantly reducing friction. This lubricant can also construct a non-polar, low-friction isolation layer on the tool surface, effectively inhibiting material adhesion. After being formulated with oleic acid triethanolamine modified nanoparticles, the "micro-ball bearing" effect further reduces the coefficient of friction, decreases heat generation, and improves thermal conductivity, achieving a synergistic effect of physical cooling and dynamic lubrication, significantly slowing down tool wear.

[0025] This invention utilizes the layered structure of hydrotalcite and the spherical morphology of nano-silica to form a "layer-sphere" composite lubrication system. This complementarity in size and morphology allows the spherical SiO2 particles to roll between the hydrotalcite layers, further reducing interlayer shear resistance. This enables the composite nanoparticle additive to improve lubrication performance and reduce friction. Furthermore, the use of triethanolamine oleate-modified nanoparticle additives significantly enhances the dispersibility and anti-friction properties of the nanoparticles in the cutting fluid while increasing their polarity. The resulting cutting fluid exhibits excellent performance and can be stored stably for extended periods.

[0026] The isooctanol polyoxyethylene ether phosphate added in this invention is not only a highly efficient extreme pressure lubricant, but also synergistically improves the lubrication performance of cutting fluids in conjunction with binary composite polyether lubricants and nano-additives. More importantly, the phosphate groups in its molecular structure can chemically adsorb onto the surfaces of aluminum and magnesium metals, forming a dense phosphate conversion film that effectively isolates corrosive media and exhibits excellent corrosion resistance.

[0027] The cutting fluid of this invention contains an appropriate amount of tannic acid. On the one hand, the hydrogen bonding between tannic acid and polyether lubricant molecules helps to form a more stable and tougher composite lubricating film in the high-temperature cutting zone, thereby improving lubrication performance and reducing tool wear. On the other hand, tannic acid not only has excellent corrosion inhibition properties, but also exhibits good friction reduction, wear resistance and corrosion inhibition properties by forming an adsorption film or magnesium-aluminum complex on the surface of magnesium-aluminum alloy. Furthermore, as a natural polyphenol, tannic acid has excellent antibacterial properties and can effectively inhibit the growth of bacteria and fungi for a long time.

[0028] This invention employs a composite binary polyether lubricant, isooctanol polyoxyethylene ether phosphate, and nanoparticle additives as the core lubrication system. The flexible polyether molecular chains can form a physically adsorbed boundary lubricating film on the metal surface. Under the high temperature and pressure of the cutting zone, isooctanol polyoxyethylene ether phosphate reacts with the fresh metal surface to generate a chemical reaction film. Combined with the nanoparticle additives, this reduces the coefficient of friction and frictional heat, forming a multi-layered regulatory mechanism of physical cooling and dynamic lubrication, significantly reducing tool wear. Simultaneously, the added surfactant reduces the surface tension of the liquid, giving it excellent wetting and penetration capabilities. The nanoparticle additives possess excellent thermal conductivity, enabling them to quickly reach the tool-workpiece-chip area, efficiently dissipating cutting heat and achieving superior cooling.

[0029] Compared with the prior art, the present invention has the following significant advantages:

[0030] This invention provides a long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys. It employs a composite water-soluble polyether lubricant, isooctyl alcohol polyoxyethylene ether phosphoric acid, and nanoparticle additives as its core lubrication system. This allows the cutting fluid to better cool the aluminum-magnesium alloy, improve its lubrication effect, reduce friction between the cutting tool and the aluminum-magnesium alloy, and thus ensure optimal machining results. Furthermore, the use of oleic acid triethanolamine-modified nanoparticle additives significantly enhances the dispersibility and anti-friction / wear-resistant properties of the nanoparticles in the cutting fluid while increasing their polarity. The resulting cutting fluid exhibits excellent performance and can be stored stably for extended periods. Detailed Implementation

[0031] To more clearly illustrate the purpose, technical solution, and advantages of this invention, the technical solution of this invention will be described in detail below through specific embodiments. It should be noted that these embodiments are only for illustrating this invention and not for limiting its scope of protection; the actual scope of protection of this invention should be determined by the claims.

[0032] Raw material description:

[0033] Polypropylene glycol monobutyl ether: purchased from Shandong Xuchen Chemical Technology Co., Ltd.

[0034] Polyoxyethylene-polyoxypropylene copolymer: molecular weight 9000-12000, purchased from Guangdong Fangxin Biotechnology Co., Ltd.

[0035] Isooctanol polyoxyethylene ether phosphate was purchased from Wuhan Maikairui Chemical Co., Ltd.

[0036] Unless otherwise specified, the materials and reagents used in the following examples and comparative examples are commercially available. Unless otherwise specified, the amount of each component in the following examples is 1 g per part by weight.

[0037] I. Examples and comparative examples of preparing long-lasting, environmentally friendly, fully synthetic cutting fluids for aluminum-magnesium alloys are as follows: Example 1

[0038] 1. Preparation of nano-additives: Take 50 mg of 50 nm nano-magnesium aluminum hydrotalcite and 10 mg of 10 nm nano-silica, disperse them in 100 mL of 80% ethanol aqueous solution, add 10 mg of triethanolamine oleate, stir and react at 20 °C for 3 h, centrifuge, wash and dry to obtain nano-additive 1#.

[0039] 2. Cutting fluid formula (mass %):

[0040] Binary composite polyether lubricant (polypropylene glycol monobutyl ether / polyoxyethylene-polyoxypropylene copolymer = 1:1): 10%

[0041] Nano-additive #1: 1.5%

[0042] Isooctyl alcohol polyoxyethylene ether phosphate: 4%

[0043] Tannic acid: 0.5%

[0044] Fatty acid polyoxyethylene ether: 2%

[0045] pH stabilizer (tris(hydroxymethyl)aminomethane): 5%

[0046] Methylbenzotriazole: 1%

[0047] 1,2-Benzisothiazolin-3-one: 1%

[0048] Defoamer (AFE-1267): 0.1%

[0049] Deionized water: Balance.

[0050] 3. Preparation process: Mix all components and stir at 30°C for 1 hour to obtain a long-lasting, environmentally friendly, fully synthetic cutting fluid. Example 2

[0051] Preparation of nano-additives: Take 80 mg of 100 nm nano-magnesium aluminum hydrotalcite and 35 mg of 30 nm nano-silica, disperse them in 150 mL of 70% ethanol aqueous solution, add 30 mg of triethanolamine oleate, stir and react at 30 °C for 2 h to obtain nano-additive 2#.

[0052] 2. Cutting fluid formula (mass %):

[0053] Binary composite polyether lubricant (polypropylene glycol monobutyl ether / polyoxyethylene-polyoxypropylene copolymer = 3:1): 15%

[0054] Nano-additive #2: 0.5%

[0055] Isooctyl alcohol polyoxyethylene ether phosphate: 2%

[0056] Tannic acid: 1%

[0057] Surfactant (castor oil polyoxyethylene ether): 6%

[0058] pH stabilizer (diethanolamine): 8%

[0059] Sodium mercaptobenzothiazole: 3%

[0060] Polyhexamethylene guanidine: 1.5%

[0061] Defoamer (AFE-1267): 1%

[0062] Deionized water: Balance.

[0063] 3. Preparation process: Mix all components and stir at 50°C for 5 hours to obtain a long-lasting, environmentally friendly, fully synthetic cutting fluid. Example 3

[0064] 1. Preparation of nano-additives: Take 75 mg of nano-magnesium aluminum hydrotalcite with a particle size of 75 nm and 30 mg of nano-silica with a particle size of 20 nm, disperse them in 150 mL of 90% ethanol aqueous solution, add 12 mg of triethanolamine oleate, stir and react at 50 °C for 1 h to obtain nano-additive 3#.

[0065] 2. Cutting fluid formula (mass %):

[0066] Binary composite polyether lubricant (polypropylene glycol monobutyl ether / polyoxyethylene-polyoxypropylene copolymer = 2:1): 5%

[0067] Nano-additive #3: 3%

[0068] Isooctyl alcohol polyoxyethylene ether phosphate: 8%

[0069] Tannic acid: 2%

[0070] Surfactant (hexadecyltrimethylammonium chloride): 8%

[0071] pH stabilizer (sodium bicarbonate): 10%

[0072] Methylbenzotriazole: 3%

[0073] Polyhexamethylene guanidine: 1%

[0074] Defoamer (AFE-1267): 0.5%

[0075] Deionized water: Balance.

[0076] 3. Preparation process: Mix all components and stir at 40°C for 3 hours to obtain a long-lasting, environmentally friendly, fully synthetic cutting fluid. Example 4

[0077] 1. Preparation of nano-additives: 90 mg of 60 nm nano-magnesium aluminum hydrotalcite and 20 mg of 25 nm nano-silica were dispersed in 150 mL of 85% ethanol aqueous solution. 10 g of triethanolamine oleate was added and the mixture was stirred at 40 °C for 2.5 h to obtain nano-additive 4#.

[0078] 2. Cutting fluid formula (mass %):

[0079] Binary composite polyether lubricant (polypropylene glycol monobutyl ether / polyoxyethylene-polyoxypropylene copolymer = 1.5:1): 8%

[0080] Nano-additive #4: 2%

[0081] Isooctyl alcohol polyoxyethylene ether phosphate: 6%

[0082] Tannic acid: 1.5%

[0083] Surfactant (sodium dodecyl sulfate): 5%

[0084] pH stabilizer (sodium tetraborate): 8%

[0085] Corrosion inhibitor (sodium benzoate + sodium molybdate in a 2:1 ratio): 2.5%

[0086] 1,2-Benzisothiazolin-3-one: 1.5%

[0087] Defoamer (AFE-1267): 0.3%

[0088] Deionized water: 68.2%.

[0089] 3. Preparation process: Mix all components and stir at 35°C for 4 hours to obtain a long-lasting, environmentally friendly, fully synthetic cutting fluid. Example 5

[0090] The difference from Example 1 is that the bactericide is a 1:1 mixture of 1,2-benzisothiazolin-3-one (BIT) and polyhexamethylene guanidine (PHMG), and the other conditions are the same as in Example 1.

[0091] Comparative Example 1

[0092] The difference from Example 2 is that the nano-additive is different, but the other conditions are the same.

[0093] The nano-additive of Comparative Example 1 was prepared as follows: 115 mg of 100 nm nano-magnesium aluminum hydrotalcite was dispersed in 150 mL of 70% ethanol aqueous solution, 30 mg of triethanolamine oleate was added, and the mixture was stirred at 30 °C for 2 h to obtain the nano-additive.

[0094] Comparative Example 2

[0095] The difference from Example 2 is that the nano-additive is different, but the other conditions are the same.

[0096] The nano-additive of Comparative Example 2 was prepared as follows: 115 mg of nano-silica with a particle size of 30 nm was dispersed in 150 mL of 70% ethanol aqueous solution, 30 mg of triethanolamine oleate was added, and the mixture was stirred at 30 °C for 2 h to obtain the nano-additive.

[0097] Comparative Example 3

[0098] The difference from Example 2 is that the nano-additive is different, but the other conditions are the same.

[0099] The nano-additive of Comparative Example 3 was prepared as follows: 80 mg of 100 nm nano-magnesium aluminum hydrotalcite and 35 mg of 30 nm nano-silica were dispersed in 150 mL of 70% ethanol aqueous solution and stirred at 30 °C for 2 h to obtain the nano-additive.

[0100] Comparative Example 4

[0101] The difference from Example 2 is that the nano-additive is different, but the other conditions are the same.

[0102] The preparation of the nano-additive in Comparative Example 4 was as follows: 80 mg of 100 nm nano-magnesium aluminum hydrotalcite and 35 mg of 30 nm nano-silica were dispersed in 150 mL of 70% ethanol aqueous solution, 30 mg of KH560 was added, and the mixture was stirred at 30 °C for 2 h to obtain the nano-additive.

[0103] Comparative Example 5

[0104] The difference from Example 2 is that the polyether lubricant is 15 wt% polypropylene glycol monobutyl ether, and the other conditions are the same as in Example 2.

[0105] Comparative Example 6

[0106] The difference from Example 2 is that the polyether lubricant is 15 wt% polyoxyethylene-polyoxypropylene copolymer, and the other conditions are the same as in Example 2.

[0107] Comparative Example 7

[0108] The difference from Example 2 is that an equal amount of deionized water is used instead of tannic acid.

[0109] Comparative Example 8

[0110] The difference from Example 2 is that an equal amount of polyoxyethylene-polyoxypropylene copolymer is used instead of isooctanol polyoxyethylene ether phosphate.

[0111] II. Experimental Data for Effect Verification

[0112] The cutting fluid stock solutions prepared in the examples and comparative examples were diluted to an 8% concentration to verify the lubrication performance, cooling performance, corrosion prevention performance and stability performance of the cutting fluids.

[0113] 1. Lubrication performance test

[0114] According to GB / T 3142-2019, the four-ball method for determining the load-carrying capacity of lubricants was used to test the friction coefficient and wear scar diameter of each cutting fluid diluent using a four-ball friction tester.

[0115] 2. Cooling performance test

[0116] On a CNC milling machine, using the same cutting tool (carbide end mill) and cutting parameters (spindle speed 8000 rpm, feed rate 3000 mm / min, depth of cut 2 mm), and using the cutting fluid of the comparative example and the embodiment (8% concentration), continuous milling of AZ91D magnesium alloy sheet was performed. The highest stable temperature near the tool tip during the cutting process was measured and recorded using an infrared thermal imager.

[0117] Table 1. Lubricating and cooling properties of cutting fluids

[0118] .

[0119] According to the test results in Table 1, the long-lasting environmentally friendly fully synthetic cutting fluids prepared in Examples 1-5 of this invention have excellent lubrication and friction reduction properties and cooling performance. The average coefficient of friction is less than 0.073, the wear scar diameter is less than 0.51 mm, and the highest stable temperature near the tool tip during cutting does not exceed 100℃. This is due to the synergistic lubrication system of composite binary polyether lubricant, isooctanol polyoxyethylene ether phosphoric acid, and nanoparticle additives, which improves the lubrication and friction reduction effect of the cutting fluid and reduces the friction between the tool and the aluminum-magnesium alloy. The nanoparticle additives have excellent thermal conductivity, which efficiently removes the cutting heat, achieves efficient cooling, reduces the cutting temperature, and ensures the machining effect on the aluminum alloy.

[0120] The nanoparticle additives in Comparative Examples 1-2 used only nano-magnesium aluminum hydrotalcite or nano-silica, which resulted in poor lubrication and thermal conductivity of the cutting fluid. The nanoparticle additive in Comparative Example 3 did not use triethanolamine oleate, which resulted in poor dispersibility of the nanoparticle additive in the cutting fluid. The lubrication and friction reduction effects of Comparative Examples 1-3 were significantly reduced, and the maximum temperature during the machining process increased.

[0121] Comparative Example 4, using a silane coupling agent to modify nanoparticles, also improved the lubrication, friction reduction, and cooling properties of the cutting fluid to some extent, but the improvement was slightly less than that of nanoparticles modified with triethanolamine oleate. This may be because triethanolamine oleate has the effect of a surfactant, which can reduce friction. At the same time, the hydroxyl groups in triethanolamine oleate have a strong bonding effect with the nanoparticles, which can improve lubrication performance and reduce the maximum temperature during machining.

[0122] Comparative Examples 5 and 6 used only polypropylene glycol monobutyl ether or polyoxyethylene-polyoxypropylene copolymer, while Comparative Example 8 did not use isooctanol polyoxyethylene ether phosphate. The lubrication effect decreased, the coefficient of friction and the diameter of the wear scar between the tool and the aluminum-magnesium alloy increased, resulting in the highest temperature during the machining process.

[0123] Comparative Example 7 omitted tannic acid. The hydrogen bonding between the tannic acid added in Example 2 and the polyether lubricant molecules helps to form a more stable and tougher composite lubricating film in the high-temperature cutting zone, thereby improving lubrication performance and reducing tool wear. In addition, tannic acid has excellent corrosion inhibition properties. By forming an adsorption film or magnesium-aluminum complex on the surface of magnesium-aluminum alloy, it exhibits good friction reduction, wear resistance and corrosion inhibition, further improving the lubrication, friction reduction and cooling performance of the cutting fluid.

[0124] 3. Corrosion resistance test

[0125] Static immersion corrosion tests were conducted according to GB / T 6147-2017 standard. Polished 6061 aluminum alloy test pieces and AZ91D magnesium alloy test pieces were completely immersed in 8% diluted cutting fluid solutions and placed in a 50℃ constant temperature chamber for 360 hours (15 days). After removal, they were cleaned and dried, and surface changes were observed. A: Surface remained bright and clear, with no discoloration or spots. B: Surface slightly darkened. C: Surface darkened with a few white spots. D: Surface severely blackened.

[0126] Table 2 Corrosion protection properties of cutting fluids

[0127] .

[0128] According to the test results in Table 2, the cutting fluid of this invention exhibits perfect corrosion inhibition capability on both aluminum and magnesium alloys, with no significant changes on the alloy surface after 15 days of immersion. In contrast, the comparative examples showed varying degrees of corrosion, particularly Comparative Example 4, which did not use the triethylamine oleate modified nanoparticle additive, and Comparative Example 7, which omitted tannic acid, and Comparative Example 8, which omitted isooctanol polyoxyethylene ether phosphate, resulting in severe corrosion of the magnesium alloy. This demonstrates that the isooctanol polyoxyethylene ether phosphate, tannic acid, and triethanolamine oleate modified nanoparticles in the formulation of this invention contribute to improving the corrosion resistance of the cutting fluid.

[0129] 4. Long-term stability testing

[0130] 20L each of the 8% dilution solutions from the examples and comparative examples were placed in a simulated machine tool cooling chamber and circulated for 8 hours daily. Water lost due to evaporation was replenished weekly, and 5g of aluminum-magnesium shavings were added weekly to simulate actual working conditions. pH and total bacterial count (CFU / mL) were sampled periodically and operated continuously for 6 months.

[0131] Table 3 Long-term stability performance of cutting fluids

[0132] .

[0133] According to the test results in Table 3, the cutting fluid of this embodiment maintained a highly stable pH value and an extremely low total bacterial count throughout the simulated use period of up to 6 months, and the liquid was clear and odorless. In contrast, Comparative Example 7, which omitted tannins, began to decline in performance after 1 month, and after 3 months, it had accumulated a large number of bacteria and emitted an odor, indicating decreased stability. Comparative Example 3, which did not use oleic acid triethanolamine-modified nanoparticles, showed nanoparticle aggregation and precipitation after 6 months of simulated cyclic use, resulting in decreased stability and affecting the normal use of the cutting fluid.

[0134] The above embodiments are merely examples to illustrate the present invention and are not intended to limit the possible implementations of the invention. Based on the disclosure of this invention, those skilled in the art can make various modifications and adjustments. It is neither possible nor necessary to list all possible implementations. Any modifications, equivalent substitutions, or improvements made within the basic principles and scope of this invention should be considered to fall within the protection scope of this invention.

Claims

1. A long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys, characterized in that, The product comprises the following components by mass percentage: 5-15% binary composite polyether lubricant, 0.5-3% nanoparticle additive, 2-8% isooctanol polyoxyethylene ether phosphate, 0.5-2% tannic acid, 2-8% surfactant, 5-15% pH stabilizer, 1-5% corrosion inhibitor, 0.5-2% bactericide, 0.1-1% defoamer, and the balance being deionized water; the binary composite polyether lubricant is composed of polypropylene glycol monobutyl ether and polyoxyethylene-polyoxypropylene copolymer mixed in a mass ratio of 1-3:1; the preparation method of the nanoparticle additive includes the following steps: dispersing nano-magnesium aluminum hydrotalcite and nano-silica in an ethanol solution, then slowly adding triethanolamine oleate and stirring the reaction, centrifuging, taking the solid and washing it to obtain the nanoparticle additive.

2. The long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys as described in claim 1, characterized in that, The ethanol solution is a 70-90% aqueous ethanol solution; the temperature of the stirring reaction is 20-50℃, and the reaction time is 1-3h.

3. The long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys as described in claim 1, characterized in that, The nano-magnesium aluminum hydrotalcite has a particle size of 50-100 nm, the nano-silica has a particle size of 10-30 nm, and the mass ratio of the nano-magnesium aluminum hydrotalcite, nano-silica, and triethanolamine oleate is 5-10:1-3:

1.

4. A long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys as described in any one of claims 1-3, characterized in that, The pH stabilizer includes at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium tetraborate, tris(hydroxymethyl)aminomethane, and diethanolamine.

5. A long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys as described in any one of claims 1-3, characterized in that, The surfactant includes at least one of fatty acid polyoxyethylene ether, castor oil polyoxyethylene ether, hexadecyltrimethylammonium chloride, sodium dodecyl sulfate, or sodium dodecylbenzene sulfonate.

6. A long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys as described in any one of claims 1-3, characterized in that, The corrosion inhibitor includes at least one of methylbenzotriazole, sodium mercaptobenzothiazole, sodium benzoate, sodium molybdate, sodium fluorosilicate, and trisodium phosphate.

7. A long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys as described in any one of claims 1-3, characterized in that, The defoamer includes at least one of polyether-modified silicone oil defoamer and polyether-type defoamer; the bactericide includes at least one of 1,2-benzisothiazolin-3-one and polyhexamethylene guanidine.

8. A method for preparing a long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys as described in any one of claims 1-7, characterized in that, The process includes the following steps: mixing the components thoroughly to obtain the long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys.

9. The method for preparing a long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys as described in claim 8, characterized in that, The mixing temperature is 30-50℃, and the mixing time is 1-5 hours.

10. The application of a long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys as described in any one of claims 1-7, or a long-lasting, environmentally friendly, fully synthetic cutting fluid for aluminum-magnesium alloys prepared according to any one of claims 8-9, in the cutting or grinding of magnesium-aluminum alloys.