Cutting fluid with combination of Pickering emulsion and MXene as well as preparation method and application of cutting fluid

Abstract

The invention relates to a cutting fluid prepared by combining a Pickering emulsion with MXene and a preparation method of the cutting fluid. The cutting fluid is prepared from an MXene nanosheet and a Pickering emulsion, the concentration of the MXene nanosheet in the Pickering emulsion is 0.1 to 0.3 weight percent, and the concentration of the MXene nanosheet in the Pickering emulsion is 0.1 to 0.3 weight percent; the Pickering emulsion is prepared from natural Pickering particles, vegetable oil and water, the content of the natural Pickering particles in the Pickering emulsion is 0.01 mol / L to 0.03 mol / L, and the concentration of the vegetable oil in the Pickering emulsion is 5 wt% to 20 wt%. According to the invention, the vegetable oil with excellent lubricating property and biodegradable property is creatively used as a footstone, and natural Pickering particles are blended as a stabilizer, so that a Pickering emulsion system is constructed; mXene is introduced, so that the novel, efficient and environment-friendly cutting fluid is successfully prepared. A novel, efficient and environment-friendly cutting fluid solution is provided for the modern manufacturing industry, and green and sustainable development of the manufacturing industry is promoted.

Description

Technical Field

[0001] This invention relates to the field of cutting fluid technology, and in particular to a cutting fluid based on response surface optimization, which combines Pickering emulsion with MXene, and its preparation method and application. Background Technology

[0002] With the rapid development of manufacturing, cutting fluids play a crucial role in metal processing. However, traditional mineral oil-based cutting fluids contain toxic, carcinogenic, and non-biodegradable additives, leading to environmental pollution and health risks. Furthermore, their insufficient thermal conductivity and cleaning capabilities limit their application in advanced manufacturing. Therefore, developing an environmentally friendly, efficient, and sustainable cutting fluid is of paramount importance.

[0003] In recent years, significant progress has been made in the development of environmentally friendly cutting fluids. These fluids are prepared using biomass raw materials such as natural oils and vegetable oils, along with environmentally friendly additives that are biodegradable, low-toxicity, low-odor, and highly penetrating, to reduce environmental pollution. However, the unsaturated fatty acids in vegetable oils are susceptible to free radical attack, have poor antioxidant capacity, low thermal stability at high temperatures, and are easily decomposed. These drawbacks limit their industrial application as cutting fluids. Furthermore, few researchers have systematically studied the influence of various factors on cutting fluid performance and found the optimal formulation combination.

[0004] Patent CN120924338A discloses a biodegradable, environmentally friendly, vegetable oil-based semi-synthetic cutting fluid and its preparation method. The cutting fluid comprises 20-30 parts of vegetable lubricating oil, 10-20 parts of alkali reserve agent, 2-5 parts of corrosion inhibitor, 3-5 parts of coupling agent, 5-8 parts of surfactant, and 6-11 parts of composite rust inhibitor. The composite rust inhibitor comprises rust inhibitor A and rust inhibitor B. Rust inhibitor A comprises N-[3-(dimethylamino)propyl]-N,N',N'-trimethyl-1,3-propanediamine, benzotriazole, sebacic acid, and 2,4,6-tris(aminohexanoic acid)-1,3,5-triazine. Rust inhibitor B comprises at least one of imidazoline compounds and fatty acid sarcosine esters.

[0005] Patent CN117050802B discloses an environmentally friendly and biodegradable cutting fluid and its preparation method. The environmentally friendly and biodegradable cutting fluid includes the following substances in parts by weight: 25-40 parts vegetable oil; 10-30 parts emulsifier; 12-20 parts lubricant; 15-25 parts rust inhibitor; 0.1-1.0 parts defoamer; 10-40 parts water; the lubricant is nanoporous carbon / molybdenum composite particles.

[0006] Traditional mineral oil-based cutting fluids pose environmental pollution and health hazards. While vegetable oil-based environmentally friendly cutting fluids have seen some development, they still face two major challenges: first, insufficient long-term stability, especially under high-temperature and high-shear conditions, they are prone to oil-water separation or oxidative deterioration; second, their functions are limited, post-use treatment is difficult, waste liquid separation is costly, and resource recycling is difficult to achieve.

[0007] Pickering emulsions, by replacing traditional surfactants with solid particles, offer a new approach to constructing stable emulsion systems. However, when applied to cutting fluids, conventional pickering particles (such as SiO2 and clay) have functional limitations: they lack active responsiveness, making efficient separation and recycling after use impossible; and their tribological performance improvement often relies on simple compounding, lacking a systematic structural design.

[0008] Therefore, preparing a uniform, long-lasting, and stable oil dispersion system that is also environmentally friendly and high-performance cutting fluid remains a huge challenge. Summary of the Invention

[0009] The purpose of this invention is to overcome the problem that existing technologies cannot make cutting fluids both environmentally friendly and long-lastingly stable, and to provide a cutting fluid based on response surface optimization, which combines Pickering emulsion with MXene, as well as its preparation method and application.

[0010] This application creatively integrates natural Pickering particle stabilization technology, response surface methodology, and MXene nanosheet reinforcement technology to address the industry challenge of both poor stability and insufficient performance in environmentally friendly cutting fluids.

[0011] This application relies on response surface methodology to prepare a small-particle-size, long-lasting stable vegetable oil-based Pickering emulsion, and introduces MXene material to enhance the lubrication and mechanical properties of the emulsion. The combination of the two is used to prepare an environmentally friendly, high-performance cutting fluid.

[0012] The objective of this invention can be achieved through the following technical solutions: A Pickering emulsion combined with MXene cutting fluid, comprising MXene nanosheets and Pickering emulsion; The concentration of MXene nanosheets in Pickering emulsion was 0.1–0.3 wt.%. Pickering emulsion is a Pickering emulsion prepared using natural Pickering particles, vegetable oil, and water. The content of natural Pickering particles in the Pickering emulsion is 0.01~0.03 mol / L, and the concentration of vegetable oil in the Pickering emulsion is 5~20 wt.%.

[0013] Preferably, the natural Pickering particles are β-cyclodextrin or chitosan; the vegetable oil is cottonseed oil.

[0014] In one embodiment of the present invention, the pH range of the Pickering emulsion is 7 to 10.

[0015] In one embodiment of the present invention, a three-factor, three-level response surface methodology experiment was conducted using the pH of the Pickering emulsion, the concentration of vegetable oil, and the content of natural Pickering particles. The stability of the Pickering emulsion was used as the response variable to optimize and obtain the most stable Pickering emulsion.

[0016] Then, MXene nanosheets are mixed with Pickering emulsion to obtain a cutting fluid in which Pickering emulsion is combined with MXene.

[0017] This application further provides a method for preparing a Pickering emulsion combined with MXene cutting fluid, comprising the following steps: (1) Disperse natural Pickering particles evenly in 5-20 parts of vegetable oil cottonseed oil and 80-95 parts of deionized water, adjust the pH, then sonicate and homogenize to obtain Pickering emulsion. (2) Mix MXene nanosheets and Pickering emulsion to obtain a cutting fluid with Pickering emulsion combined with MXene.

[0018] In one embodiment of the present invention, in step (1), the concentration of natural Pickering particles in the Pickering emulsion is 0.01~0.03 mol / L.

[0019] In one embodiment of the present invention, in step (1), the ultrasonic time is 5~10 min, and then the homogenization is carried out at a speed of 8000~12000 rpm for 5~10 min.

[0020] In one embodiment of the present invention, in step (1), the pH range is 7 to 10.

[0021] In one embodiment of the present invention, in step (2), when mixing MXene nanosheets and Pickering emulsion, a homogenizer is used to disperse the MXene nanosheets evenly at a speed of 8000~12000 rpm for 5~10 min, so that they are evenly dispersed in the Pickering emulsion.

[0022] In one embodiment of the present invention, the method for preparing a Pickering emulsion combined with MXene cutting fluid specifically includes the following steps: S1: To prepare MXene nanosheets, LiF was dissolved in 6 M HCl, and then Ti3AlC2 powder was slowly added. The mixture was heated at 40-50 °C for 40-50 hours. After etching, the nanosheets were washed several times with water, centrifuged to remove reactants and increase the pH value, and finally lyophilized to obtain MXene nanosheets. S2: Natural Pickering particles are uniformly dispersed in 5-20 parts of cottonseed oil and 80-95 parts of deionized water. The pH is adjusted, followed by sonication for 5-10 min, and then homogenization at 8000-12000 rpm for 5-10 min to obtain a Pickering emulsion. The concentration of natural Pickering particles in the Pickering emulsion is 0.01-0.03 mol / L, and the concentration of vegetable oil in the Pickering emulsion is 5-20 wt.%. S3: Mix MXene nanosheets and Pickering emulsion to achieve a concentration of 0.1~0.3 wt.% for the MXene nanosheets in the Pickering emulsion. Use a homogenizer at 8000~12000 rpm for 5~10 min to uniformly disperse the MXene nanosheets in the Pickering emulsion, obtaining a cutting fluid combining Pickering emulsion and MXene. In one embodiment of the invention, a LiF / HCl solution is introduced in step S1 for etching. This results in a high proportion of oxygen-containing functional groups on the surface of the prepared MXene nanosheets, making it easier to form hydrogen bonds. During cutting, this facilitates adsorption onto the friction pair to form a robust and dense lubricating film. The average sheet size of the obtained MXene nanosheets is approximately 600 nm.

[0023] Preferably, the pH range in step S2 is 7 to 10.

[0024] In one embodiment of the present invention, preferably, the stable pickering emulsion formulation system is as follows: the pickering particles are selected with a β-cyclodextrin content of 0.010 mol / L, a pH of 8.9, and a vegetable oil concentration of 19.8 wt.%. In one embodiment of the present invention, preferably, the stable pickering emulsion formulation system is as follows: the pickering particles are selected with a chitosan content of 0.011 mol / L, a pH of 5.3, and a vegetable oil concentration of 17.1 wt.%.

[0025] The present invention further provides the application of Pickering emulsion combined with MXene cutting fluid in metal processing.

[0026] As mentioned above, the core innovation of this application lies in the creative integration of natural Pickering particle stabilization technology, response surface methodology, and MXene nanosheet enhancement technology, aiming to solve the industry problem of "poor stability" and "insufficient performance" in environmentally friendly cutting fluids.

[0027] Specifically, the core improvements of this application mainly include the following aspects: 1. Breakthrough in Pickering Emulsion Stability Mechanism: Unlike traditional emulsions that rely on small-molecule surfactants, this application uses natural polymers (β-cyclodextrin and chitosan) as Pickering particles. The stabilization mechanism is based on the irreversible adsorption of solid particles at the oil / water interface, forming a rigid physical barrier. This "armor" structure effectively hinders droplet aggregation (Ostwald ripening and flocculation), thus endowing the emulsion with extraordinary long-term kinetic stability. The "externally hydrophilic and internally hydrophobic" cavity structure of β-cyclodextrin and the amino / hydroxyl groups on the chitosan molecular chain enable it to be synergistically anchored at the interface through hydrogen bonding, hydrophobic interactions, and steric hindrance effects. This is a multi-mechanism synergistic interfacial self-assembly process, unmatched by traditional emulsifiers.

[0028] 2. Precise Component and Process Optimization Based on Response Surface Methodology: This application does not simply mix raw materials, but introduces response surface methodology (RSM) to systematically optimize pH, oil phase concentration, and particle concentration. Based on this, the optimal process window for emulsion stability was precisely identified (e.g., for the β-cyclodextrin system: pH 8.9, oil concentration 19.8%). This optimization ensures that Pickering particles achieve the densest packing at the interface, forming the most robust interfacial film, maximizing the inherent advantages of the system, and is key to reproducibility and industrial scale-up.

[0029] 3. Multifunctional Synergistic Enhancement Mechanism of MXene Nanosheets: This application introduces MXene, whose role goes far beyond the simple physical rolling of a "microsphere bearing." Specifically, its synergistic stabilization effect on the interface is manifested in the following ways: The abundant oxygen-containing functional groups (-OH, -O) at the edges of MXene sheets can form hydrogen bond networks with Pickering particles (such as -NH2 in chitosan) or water molecules, partially embedding and strengthening the Pickering interface film, thereby improving the mechanical strength of the interface structure. Tribochemical Film Formation: Under the high temperature and pressure of friction, MXene sheets can undergo shearing and spreading on the surface of the friction pair, and undergo tribochemical reactions with the metal substrate to form an adaptive solid lubrication transfer film rich in carbon and titanium oxides. This film has extremely low shear strength, effectively converting sliding friction into interlaminar shear, thus significantly reducing friction and wear. Thermal Conductivity and Load Bearing: The excellent thermal conductivity of MXene can quickly dissipate frictional heat, reduce the temperature of the contact area, and alleviate oil oxidation and failure. Its two-dimensional sheet structure provides a larger load-bearing area, improving the extreme pressure resistance of the lubricating film.

[0030] This invention provides a cutting fluid combining a Pickering emulsion and MXene based on response surface methodology, comprising an environmentally friendly Pickering emulsion and MXene nanosheets. Natural Pickering particles (β-cyclodextrin, chitosan, etc.) are used as stabilizers, self-assembling at the oil-water interface to form crystalline nanoparticles that adsorb onto the surface of oil droplets, maintaining the long-term stability of the emulsion during emulsification. The Pickering emulsion system is carefully constructed, and the preparation process is optimized using response surface methodology. Secondly, the cutting-edge nanomaterial MXene is introduced, which can act as a "micro-bearing," significantly improving the tribological and mechanical properties of the Pickering emulsion. The combination of these two components successfully prepares a novel, efficient, and environmentally friendly cutting fluid, providing a new avenue for the application of Pickering emulsions and promoting the green and sustainable development of the manufacturing industry.

[0031] Compared with the prior art, the present invention has the following beneficial effects: 1. A balance between long-term stability and high performance: The response surface optimization of Pickering emulsion solves the fundamental problem of easy stratification in vegetable oil-based emulsions (stabilization time > 1000 hours), providing a stable "delivery platform" for high performance. The addition of MXene further enhances tribological properties (friction reduction, wear resistance) and heat dissipation performance to levels exceeding those of commercially available products. This design approach of "stable carrier + high-efficiency functional agent" achieves a balance between environmental protection and high efficiency.

[0032] 2. Dual Enhancement of Interface and Bulk Phase: Natural Pickering particles (β-cyclodextrin, chitosan, etc.) are used as stabilizers, self-assembling and aggregating at the oil-water interface to form crystalline nanoparticles that adsorb onto the oil droplet surface, maintaining the long-term stability of the emulsion during emulsification. MXene acts as a lubricating additive in the bulk phase and forms a protective film at the friction interface. The complementary roles of these two components together construct a high-performance system covering the entire process from emulsion storage and transport to final lubrication.

[0033] 3. A Balance Between Environmental Friendliness and Superior Performance: By replacing traditional petroleum-based oils and synthetic surfactants with natural particles and vegetable oils, biodegradability and low toxicity are achieved from the source. Furthermore, the introduction of MXene, an advanced nanomaterial, compensates for the inherent deficiencies of pure vegetable oils in extreme pressure anti-wear and thermal conductivity. This results in a final product that is more environmentally friendly than traditional cutting fluids and catches up with or even surpasses traditional cutting fluids in core performance aspects (such as lower coefficient of friction and smaller wear scars), addressing the industry pain point of weak performance in environmentally friendly cutting fluids.

[0034] 4. During the preparation of MXene sheets, LiF / HCl solution was used for etching, which resulted in a high proportion of oxygen-containing functional groups on the surface of the prepared MXene nanosheets, making it easier to form hydrogen bonds. This helps to adsorb onto the friction pair during cutting and form a strong and dense lubricating film. Attached Figure Description

[0035] Figure 1 The response surface graph shows the stability of the Pickering emulsion in Example 1, where a represents pH value and cottonseed oil concentration; b represents pH value and β-cyclodextrin content; and c represents cottonseed oil concentration and β-cyclodextrin content.

[0036] Figure 2 The response surface graph for the stability of the Pickering emulsion in Example 2 is shown below: where a represents pH value and cottonseed oil concentration; b represents pH value and chitosan content; and c represents cottonseed oil concentration and chitosan content. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0038] Example 1 The preparation steps of a Pickering emulsion combined with MXene cutting fluid are as follows: (1) To prepare MXene nanosheets, LiF was dissolved in 6 M HCl, and then Ti3AlC2 powder was slowly added. The mixture was heated at 45 °C for 45 hours. After etching, the nanosheets were washed several times with water, centrifuged to remove reactants and increase the pH value, and finally the resulting deposits were freeze-dried for later use. (2) β-cyclodextrin was uniformly dispersed in 10 parts of cottonseed oil and 90 parts of deionized water, the pH was adjusted to 8, and then sonicated for 10 min, and then homogenized at 12000 rpm for 5 min to obtain dispersion system A. Finally, the concentration of β-cyclodextrin in Pickering emulsion was 0.02 mol / L, and the concentration of cottonseed oil in Pickering emulsion was 10 wt.%. The preparation process of Pickering emulsion was optimized by response surface methodology, and different formulations were obtained, as shown in Table 1. Table 1 Response surface optimization of Pickering emulsion formulations As shown in Table 1, a three-factor, three-level response surface methodology experiment was conducted using pH, cottonseed oil concentration, and β-cyclodextrin content, with the stability (stabilization time) of the pickering emulsion as the response variable. The results are as follows: Figure 1 As shown. Analysis revealed that the optimal formulation for preparing Pickering emulsion was: pH 8.9, cottonseed oil concentration 19.8 wt.%, and β-cyclodextrin content 0.010 mol / L. Pickering emulsion was prepared using this formulation. (3) Mix MXene nanosheets and Pickering emulsion to make the concentration of MXene nanosheets in Pickering emulsion 0.1 wt.% and use a homogenizer at 8000~12000 rpm for 5~10 min to disperse MXene nanosheets evenly and make them evenly dispersed in Pickering emulsion to obtain a cutting fluid with Pickering emulsion combined with MXene.

[0039] Tribological performance testing: The performance of Pickering emulsion + MXene was evaluated by four-ball friction test, tapping torque test, thermal conductivity test and contact angle test on the optimally formulated Pickering emulsion, Pickering emulsion + MXene and commercially available cutting fluid.

[0040] The four-ball friction test is used to evaluate the wear resistance, extreme pressure properties, and coefficient of friction of lubricants. In the four-ball friction and wear tester, three stationary steel balls (immersed in lubricant) form point contact with one rotating steel ball. Under set loads, rotation speeds, and time, a friction pair is simulated, and the coefficient of friction is calculated by measuring the wear scar diameter and frictional torque.

[0041] Tapping torque tests are used to evaluate the lubrication effect of lubricants in actual cutting processes; lower tapping torque indicates better lubrication. The tapping process is simulated by measuring the torque and axial force as the tap enters the workpiece. Reduced torque indicates that the lubricant effectively reduces friction.

[0042] Thermal conductivity testing is used to measure the thermal conductivity of lubricants, as heat dissipation performance is crucial for cutting fluids. The transient hot-wire method is employed to calculate the thermal conductivity (λ, in W / (m·K)) by measuring heat flux and temperature gradient.

[0043] Contact angle experiments are used to characterize the wetting and spreading ability of lubricants on metal surfaces. A smaller contact angle indicates better wettability and promotes lubricant film formation. Using a contact angle measuring instrument, a droplet is placed on a solid surface, and the droplet profile is fitted using the Young-Laplace equation to calculate the contact angle.

[0044] The above experiments are all standard inspection methods in this field.

[0045] Table 2. Performance comparison between the prepared cutting fluid and commercially available cutting fluid Based on the average friction coefficient and average wear scar diameter results in Table 2, it can be seen that the Pickering emulsion + MXene has a lower friction coefficient and a smaller wear diameter compared to the Pickering emulsion and commercially available cutting fluids, indicating that the novel cutting fluid of this invention has better friction reduction and anti-wear performance; the introduction of MXene can effectively reduce its tapping torque; the introduction of MXene can effectively improve the thermal conductivity of the Pickering emulsion; the introduction of MXene can reduce the contact angle of the Pickering emulsion.

[0046] Comparative Example 1 The preparation steps of a Pickering emulsion combined with MXene cutting fluid are as follows: (1) To prepare MXene nanosheets, LiF was dissolved in 6 M HCl, and then Ti3AlC2 powder was slowly added. The mixture was heated at 50 °C for 50 hours. After etching, the nanosheets were washed several times with water, centrifuged to remove reactants and increase the pH value, and finally the resulting deposits were freeze-dried for later use. (2) β-cyclodextrin was uniformly dispersed in 19.8 parts of cottonseed oil and 80.2 parts of deionized water, and the pH was adjusted to 8.9. Then, the mixture was sonicated for 10 min and homogenized at 12000 rpm for 5-10 min to obtain a Pickering emulsion. The final concentration of β-cyclodextrin in the Pickering emulsion was 0.010 mol / L, and the concentration of cottonseed oil in the Pickering emulsion was 19.8 wt.%. (3) Mix MXene nanosheets and Pickering emulsion to make the concentration of MXene nanosheets in Pickering emulsion 0.2 wt.% and use a homogenizer at 8000~12000 rpm for 5~10 min to disperse MXene nanosheets evenly and make them evenly dispersed in Pickering emulsion to obtain a cutting fluid with Pickering emulsion combined with MXene.

[0047] Tribological performance testing: The performance of Pickering emulsion + MXene was evaluated by four-ball friction test, tapping torque test, thermal conductivity test and contact angle test on the optimally formulated Pickering emulsion, Pickering emulsion + MXene and commercially available cutting fluid.

[0048] Table 3. Performance comparison between the prepared cutting fluid and commercially available cutting fluid Based on the average friction coefficient and average wear scar diameter results in Table 3, it can be seen that the Pickering emulsion + MXene has a lower friction coefficient and a smaller wear diameter compared to the Pickering emulsion and commercially available cutting fluids, indicating that the novel cutting fluid of this invention has better friction reduction and anti-wear performance; the introduction of MXene can effectively reduce its tapping torque; the introduction of MXene can effectively improve the thermal conductivity of the Pickering emulsion; the introduction of MXene can reduce the contact angle of the Pickering emulsion.

[0049] Comparative Example 2 The preparation steps of a Pickering emulsion combined with MXene cutting fluid are as follows: (1) To prepare MXene nanosheets, LiF was dissolved in 6 M HCl, and then Ti3AlC2 powder was slowly added. The mixture was heated at 40-50 °C for 40-50 hours. After etching, the nanosheets were washed several times with water, centrifuged to remove reactants and increase the pH value, and finally the resulting deposits were freeze-dried for later use. (2) β-cyclodextrin was uniformly dispersed in 19.8 parts of cottonseed oil and 80.2 parts of deionized water, the pH was adjusted to 8.9, and then sonicated for 5-10 min, and then homogenized at 8000-12000 rpm for 5-10 min to obtain Pickering emulsion. The final concentration of β-cyclodextrin in Pickering emulsion was 0.010 mol / L, and the concentration of cottonseed oil in Pickering emulsion was 19.8 wt.%. The preparation process of Pickering emulsion was optimized by response surface methodology. (3) Mix MXene nanosheets and Pickering emulsion to make the concentration of MXene nanosheets in Pickering emulsion 0.3 wt.% and use a homogenizer at 8000~12000 rpm for 5~10 min to disperse MXene nanosheets evenly and make them evenly dispersed in Pickering emulsion to obtain a cutting fluid with Pickering emulsion combined with MXene.

[0050] Tribological performance testing: The performance of Pickering emulsion + MXene was evaluated by four-ball friction test, tapping torque test, thermal conductivity test and contact angle test on the optimally formulated Pickering emulsion, Pickering emulsion + MXene and commercially available cutting fluid.

[0051] Table 4. Performance comparison between the prepared cutting fluid and commercially available cutting fluid The average friction coefficient and average wear scar diameter results in Table 4 show that the Pickering emulsion + MXene has a lower friction coefficient and a smaller wear scar diameter compared to the Pickering emulsion and commercially available cutting fluids, indicating that the novel cutting fluid of this invention has better friction reduction and anti-wear properties. The introduction of MXene can effectively reduce its tapping torque. The introduction of MXene can effectively improve the thermal conductivity of the Pickering emulsion. The introduction of MXene can reduce the contact angle of the Pickering emulsion, improve its wettability and spreadability on metal workpieces, and enhance the ability to form a lubricating film.

[0052] Performance tests and analyses of Examples 1, 1, and 2 showed that increasing the concentration of MXene nanosheets in Pickering emulsion can significantly improve the thermal conductivity of Pickering emulsion and enhance its wettability and spreadability on metal surfaces. However, the tribological properties are optimal at 0.1 wt.%, and slightly decrease with higher concentrations.

[0053] Example 2 The preparation steps of a Pickering emulsion combined with MXene cutting fluid are as follows: (1) To prepare MXene nanosheets, LiF was dissolved in 6 M HCl, and then Ti3AlC2 powder was slowly added. The mixture was heated at 40-50 °C for 40-50 hours. After etching, the nanosheets were washed several times with water, centrifuged to remove reactants and increase the pH value, and finally the resulting deposits were freeze-dried for later use. (2) Chitosan was evenly dispersed in 5-20 parts of cottonseed oil and 80-95 parts of deionized water, and the pH was adjusted to 3-6. Then, the mixture was sonicated for 5-10 min and homogenized at 8000-12000 rpm for 5-10 min to obtain Pickering emulsion. The final concentration of chitosan in Pickering emulsion was 0.01-0.03 mol / L, and the concentration of cottonseed oil in Pickering emulsion was 5-20 wt.%.

[0054] Table 5 Response Surface Optimization of Pickering Emulsion Formulation As shown in Table 5, a three-factor, three-level response surface methodology experiment was conducted using pH, cottonseed oil concentration, and chitosan content, with the stability of the pickering emulsion as the response variable. The results are as follows: Figure 2 As shown. Analysis revealed that the optimal formulation for preparing the Pickering emulsion was: pH 5.3, cottonseed oil concentration 17.1 wt.%, and chitosan content 0.011 mol / L. Dispersion system A was prepared using this formulation. (3) Mix MXene nanosheets with dispersion system A to make the concentration of MXene nanosheets in Pickering emulsion 0.1 wt.%, and use a homogenizer at 8000~12000 rpm for 5~10 min to disperse MXene nanosheets evenly, so that they are evenly dispersed in Pickering emulsion to obtain dispersion system B; (4) After the dispersion system B is tested and found to be qualified, it is discharged, canned, packaged and put into storage.

[0055] Tribological performance testing: The performance of Pickering emulsion + MXene was evaluated by four-ball friction test, tapping torque test, thermal conductivity test and contact angle test on the optimally formulated Pickering emulsion, Pickering emulsion + MXene and commercially available cutting fluid.

[0056] Table 6. Performance Comparison between the Prepared Cutting Fluid and Commercially Available Cutting Fluids Based on the average friction coefficient and average wear scar diameter results in Table 6, it can be seen that the Pickering emulsion + MXene has a lower friction coefficient and a smaller wear diameter compared to the Pickering emulsion and commercially available cutting fluids, indicating that the novel cutting fluid of this invention has better friction reduction and anti-wear performance; the introduction of MXene can effectively reduce its tapping torque; the introduction of MXene can effectively improve the thermal conductivity of the Pickering emulsion; the introduction of MXene can reduce the contact angle of the Pickering emulsion.

[0057] Comparative Example 3 The preparation steps of a Pickering emulsion combined with MXene cutting fluid are as follows: (1) To prepare MXene nanosheets, LiF was dissolved in 6 M HCl, and then Ti3AlC2 powder was slowly added. The mixture was heated at 40-50 °C for 40-50 hours. After etching, the nanosheets were washed several times with water, centrifuged to remove reactants and increase the pH value, and finally the resulting deposits were freeze-dried for later use. (2) Chitosan was evenly dispersed in 17.1 parts of cottonseed oil and 82.9 parts of deionized water, the pH was adjusted to 5.3, and then sonicated for 5-10 min, and then homogenized at 8000-12000 rpm for 5-10 min to obtain Pickering emulsion. The final concentration of chitosan in Pickering emulsion was 0.011 mol / L, and the concentration of cottonseed oil in Pickering emulsion was 17.1 wt.%.

[0058] (3) Mix MXene nanosheets and Pickering emulsion to make the concentration of MXene nanosheets in Pickering emulsion 0.2 wt.% and use a homogenizer at 8000~12000 rpm for 5~10 min to disperse MXene nanosheets evenly and make them evenly dispersed in Pickering emulsion to obtain a cutting fluid with Pickering emulsion combined with MXene.

[0059] Tribological performance testing: The performance of Pickering emulsion + MXene was evaluated by four-ball friction test, tapping torque test, thermal conductivity test and contact angle test on the optimally formulated Pickering emulsion, Pickering emulsion + MXene and commercially available cutting fluid.

[0060] Table 7 Comparison of the performance of the prepared cutting fluid and commercially available cutting fluid The average friction coefficient and average wear scar diameter results in Table 7 show that the Pickering emulsion + MXene has a lower friction coefficient and a smaller wear scar diameter compared to the Pickering emulsion and commercially available cutting fluids, indicating that the novel cutting fluid of this invention has better friction reduction and anti-wear properties. The introduction of MXene can effectively reduce its tapping torque. The introduction of MXene can effectively improve the thermal conductivity of the Pickering emulsion. The introduction of MXene can reduce the contact angle of the Pickering emulsion.

[0061] Comparative Example 4 The preparation steps of a Pickering emulsion combined with MXene cutting fluid are as follows: (1) To prepare MXene nanosheets, LiF was dissolved in 6 M HCl, and then Ti3AlC2 powder was slowly added. The mixture was heated at 40-50 °C for 40-50 hours. After etching, the nanosheets were washed several times with water, centrifuged to remove reactants and increase the pH value, and finally the resulting deposits were freeze-dried for later use. (2) Chitosan was uniformly dispersed in 17.1 parts of cottonseed oil and 82.9 parts of deionized water, and the pH was adjusted to 5.3. Then, the mixture was sonicated for 5-10 min and homogenized at 8000-12000 rpm for 5-10 min to obtain a Pickering emulsion. The final concentration of chitosan in the Pickering emulsion was 0.011 mol / L, and the concentration of cottonseed oil in the Pickering emulsion was 17.1 wt.%. (3) Mix MXene nanosheets and Pickering emulsion to make the concentration of MXene nanosheets in Pickering emulsion 0.3 wt.% and use a homogenizer at 8000~12000 rpm for 5~10 min to disperse MXene nanosheets evenly and make them evenly dispersed in Pickering emulsion to obtain a cutting fluid with Pickering emulsion combined with MXene.

[0062] Tribological performance testing: The performance of Pickering emulsion + MXene was evaluated by four-ball friction test, tapping torque test, thermal conductivity test and contact angle test on the optimally formulated Pickering emulsion, Pickering emulsion + MXene and commercially available cutting fluid.

[0063] Table 8. Performance comparison between the prepared cutting fluid and commercially available cutting fluid Based on the average friction coefficient and average wear scar diameter results in Table 8, it can be seen that the Pickering emulsion + MXene has a lower friction coefficient and a smaller wear diameter compared to the Pickering emulsion and commercially available cutting fluids, indicating that the novel cutting fluid of this invention has better friction reduction and anti-wear performance; the introduction of MXene can effectively reduce its tapping torque; the introduction of MXene can effectively improve the thermal conductivity of the Pickering emulsion; the introduction of MXene can reduce the contact angle of the Pickering emulsion.

[0064] Performance tests and analyses of Examples 2, 3, and 4 showed that increasing the concentration of MXene nanosheets in Pickering emulsion significantly improved the thermal conductivity and wettability of the emulsion on metal surfaces. However, the tribological properties were optimal at 0.1 wt.%, with higher concentrations showing a slight decrease. Overall, the optimal concentration of MXene is 0.1–0.2 wt.%, achieving the best balance between friction reduction / wear resistance and heat dissipation performance.

[0065] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A cutting fluid combining a Pickering emulsion with MXene, characterized in that, Including MXene nanosheets and Pickering emulsion; The concentration of the MXene nanosheets in the Pickering emulsion was 0.1–0.3 wt.%. The Pickering emulsion is prepared using natural Pickering particles, vegetable oil, and water, wherein the content of natural Pickering particles in the Pickering emulsion is 0.01~0.03 mol / L, and the concentration of vegetable oil in the Pickering emulsion is 5~20 wt.%.

2. The cutting fluid combining Pickering emulsion and MXene according to claim 1, characterized in that, The natural Pickering particles are β-cyclodextrin or chitosan; the vegetable oil is cottonseed oil.

3. The cutting fluid combining Pickering emulsion and MXene according to claim 1, characterized in that, The pH range of the Pickering emulsion is 7 to 10.

4. A method for preparing a cutting fluid combining Pickering emulsion and MXene as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Disperse natural Pickering particles evenly in 5-20 parts of vegetable oil cottonseed oil and 80-95 parts of deionized water, adjust the pH, then sonicate and homogenize to obtain Pickering emulsion. (2) Mix MXene nanosheets and Pickering emulsion to obtain a cutting fluid with Pickering emulsion combined with MXene.

5. The method for preparing a Pickering emulsion combined with MXene cutting fluid according to claim 4, characterized in that, In step (1), the concentration of natural Pickering particles in the Pickering emulsion is 0.01~0.03 mol / L.

6. The method for preparing a Pickering emulsion combined with MXene cutting fluid according to claim 4, characterized in that, In step (1), the sonication time is 5~10 min, and then homogenization is performed at 8000~12000 rpm for 5~10 min. In step (1), the pH range is 7~10.

7. The method for preparing a Pickering emulsion combined with MXene cutting fluid according to claim 4, characterized in that, In step (2), when mixing MXene nanosheets and Pickering emulsion, a homogenizer is used to disperse the MXene nanosheets evenly at a speed of 8000~12000 rpm for 5~10 min, so that they are evenly dispersed in the Pickering emulsion.

8. The method for preparing a Pickering emulsion combined with MXene cutting fluid according to claim 4, characterized in that, The stable pickering emulsion formulation system is as follows: the pickering particles are selected as β-cyclodextrin, the β-cyclodextrin content is 0.010 mol / L, the pH is 8.9, and the vegetable oil concentration is 19.8 wt.%.

9. The method for preparing a Pickering emulsion combined with MXene cutting fluid according to claim 3, characterized in that, The stable pickering emulsion formulation system is as follows: the pickering particles are chitosan, the chitosan content is 0.011 mol / L, the pH is 5.3, and the vegetable oil concentration is 17.1 wt.%.

10. The application of the Pickering emulsion combined with MXene cutting fluid according to any one of claims 1-3 in metal processing.

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