A method for preparing graphene-based nanofluid cutting fluid

Abstract

The present invention belongs to the technical field of cutting fluids, and specifically relates to a method for preparing a graphene-based nanofluid cutting fluid. The present invention selects a dispersant and a dispersing aid of a specific structure, adds graphite or expanded graphite to a dispersant solution, and then performs hydroxyl radical stripping, and then centrifugal separation to obtain a uniform and stable graphene-based nanofluid cutting fluid. The separated solid is reused for the next production; the graphene-based nanofluid prepared by the method of the present invention has the remarkable characteristics of good dispersion stability, does not contain additives necessary for traditional lubricating oils, and has little environmental pollution effect. In addition, the preparation process is simple, the cost is low, and the service life is long; the product of the present invention exhibits comprehensive effects such as significant drag reduction, extended tool life, improved workpiece product quality, and significantly reduced post-processing costs, and is suitable for use in various types of metals and alloy materials under different cutting conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of cutting fluids, and in particular relates to a method for preparing a graphene-based nanofluid cutting fluid. Background Art

[0002] Cutting is currently one of the main and most critical means of forming metal parts. In the process of high-speed and precision cutting of metal, under the same conditions of machine tools, workpieces, cutting tools, and processing procedures, by selecting appropriate cutting fluids, it can significantly promote the reduction of friction, improvement of heat dissipation conditions, reduction of processing area temperature, extension of tool life, improvement of workpiece accuracy, and reduction of workpiece surface roughness. It is a practical and key measure to achieve the comprehensive benefits of cutting. With the acceleration of product innovation, industrial structure upgrading, and intelligent manufacturing in my country's manufacturing industry, the development of high-performance and environmentally friendly metal cutting fluids has become very urgent, and it is also one of the most effective ways to achieve carbon emission reduction in the metal processing process. Because the greenness, lubricity, excellent heat transfer, and reusability (lifespan) of cutting fluid products determine the economic and environmental benefits of the cutting process.

[0003] Traditional cutting fluid is made of water and oil as the base fluid, and then added with oiliness agent, extreme pressure agent, rust inhibitor, mildew inhibitor, defoamer and antioxidant and other additives. Traditional cutting fluid is relatively mature in terms of composition and design, so there is limited room for improvement in lubrication performance, heat transfer performance, penetration performance and other aspects. In particular, because it contains a sufficient amount of organic components, it has a short service life and is easy to deteriorate, which affects the life of the tool and the quality of the workpiece. The post-processing of the cutting fluid brings high expenses to users and adverse effects on the environment.

[0004] In recent years, researchers have explored the preparation of nanofluids by adding nano-scale ultrafine nanoparticles (particle size between 1-100nm) to the base fluid for efficient cooling and lubrication processes. Since nanoparticles have large surface area and heat capacity, and good thermal conductivity, nanofluid cutting fluids have better heat exchange performance, can significantly reduce the temperature in the cutting zone, and improve the service life of the tool and the processing quality of the workpiece. In addition, nanoparticles also have good friction reduction properties, which can further improve the lubrication performance of the cutting fluid. However, due to the influence of various forces or potential energy on the internal particles of the nanofluid, collisions and agglomerations are inevitable. The random motion speed of these agglomerates is lower than that of a single particle. Agglomerates that are too large will accelerate sedimentation and precipitate under the action of gravity, resulting in the failure of the excellent comprehensive performance of the nanofluid, which greatly limits the wide application of nanofluids in the industrial field.

[0005] Graphene has excellent thermal conductivity, electrical conductivity, mechanical strength and bactericidal properties, which give it important essential characteristics as a cutting fluid, such as thermal conductivity, friction reduction, metal corrosion passivation and bactericidal properties. At present, there are Chinese patent applications for cutting fluids containing graphene (CN113817533A, CN107603724, CN113563940A, CN113652292A, CN109054977B, CN104593132B), and its main technical features are that graphene or graphene oxide dispersion is added to the existing cutting fluid or compounded according to the existing technical formula of its cutting fluid. Although the performance of the cutting fluid is improved, it still cannot solve the bottleneck problems of the current industrial cutting fluid, such as short service life, difficulty in post-expiration treatment and poor comprehensive application performance, and no effective evaluation results are given for the stability and long-term use of graphene-based cutting fluids, so the feasibility of its practical application cannot be determined. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned problems existing in the traditional technology, and provide a method for preparing a graphene-based nanofluid cutting fluid. Through the innovation of the formula and the preparation process, a new graphene-based nanofluid cutting fluid is prepared. The graphene-based nanofluid cutting fluid of the present invention is composed of a small amount of organic dispersant, graphene and a large amount of water, and does not use other functional additives. The cutting fluid can be used for a long time, the post-processing is simple, the raw material production cost is low, and the production and use processes are green and environmentally friendly.

[0007] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0008] The present invention provides a method for preparing a graphene-based nanofluid cutting fluid, comprising the following steps:

[0009] 1) mixing and dissolving a dispersant and a dispersing aid in water to obtain a stripping aid solution;

[0010] 2) mixing graphite or expanded graphite and a stripping aid solution, and then pre-dispersing the mixture by ultrasonication to obtain a dispersion of graphite or expanded graphite;

[0011] 3) The graphite dispersion is subjected to a stripping reaction and centrifugal separation in a hydroxyl radical generator, and an upper layer of liquid is taken after the centrifugation, and the upper layer of liquid is the graphene-based nanofluid cutting fluid.

[0012] Furthermore, in step 1), the dispersant is at least one of xanthan gum, carboxymethyl chitosan, sodium pentosan sulfate, sodium cellulose acetate, sodium polystyrene sulfonate, and polyethylene oxide.

[0013] Furthermore, in step 1), the dispersing aid is at least one of sodium alginate, PEG-400, PEG-200, Tween 80, and Tween 60.

[0014] Furthermore, in step 2), the carbon content of the graphene or expanded graphite is higher than 95.0%, and the particle size is 1500 to 10000.

[0015] Furthermore, in step 2), the mass ratio of graphite or expanded graphite to the stripping aid solution is 0.0001 to 0.05.

[0016] Furthermore, in step 3), the mixing of graphite or expanded graphite and the dispersant solution is carried out by ultrasonic dispersion, with an ultrasonic power of 200 to 700 W and an ultrasonic time of 30 to 120 min.

[0017] Furthermore, in step 3), the preparation reaction conditions of the graphene-based nanofluid cutting fluid are: temperature 20-40° C., air flow rate 0.5-10 L / h, current 1-20 A, and time 0.5-6 h.

[0018] Furthermore, in step 3), during the preparation of the graphene-based nanofluid cutting fluid, the solid-liquid separation method is centrifugal separation, the centrifugal speed is 3000-8000 rpm, and the time is 10-60 min.

[0019] Furthermore, in step 3), the solid separated from the reaction system for preparing the graphene-based nanofluid cutting fluid is used as a raw material for preparing the next graphene-based nanofluid cutting fluid.

[0020] The present invention also provides a graphene-based nanofluid cutting fluid, which is prepared by the above-mentioned graphene-based nanofluid cutting fluid preparation method. The graphene-based nanofluid cutting fluid product prepared by the present invention is suitable for use in various metal and alloy materials under different cutting processing conditions.

[0021] The beneficial effects of the present invention are:

[0022] 1. The present invention selects a dispersant system with specific functions, combines the action of free radicals to exfoliate graphite and disperse the product graphene at the same time, and then separates the graphite that is not effectively exfoliated to obtain a graphene-based nanofluid cutting fluid with excellent stability. No vegetable oil, defoamer, preservative, extreme pressure agent, or pH adjustment agent is added during the preparation process, and the product has significant environmental friendliness. When used as a cutting fluid, it exhibits excellent comprehensive performance and a long service life in the cutting of various metal and alloy materials.

[0023] 2. The graphene-based nanofluid cutting fluid prepared by the present invention has excellent comprehensive performance, good dispersion stability, long service life (2 years), and shows drag reduction, extended tool life, and improved product quality. In particular, since the number of cutting fluid replacements can be significantly reduced, the post-processing cost is significantly reduced compared with the cutting fluid currently used in industry, and the adverse impact of the product on the environment is reduced.

[0024] 3. The composition of the graphene-based nanofluid cutting fluid prepared by the present invention is simple. Compared with the currently widely used water-based / oil-based nanofluids, the graphene-based nanofluid cutting fluid of the present invention is composed of a small amount of organic dispersant, graphene and a large amount of water, and does not use other functional additives. It can effectively realize the long-term use of the cutting fluid, the post-processing is simple, and the comprehensive effect of the product use is excellent.

[0025] 4. The preparation process of the graphene-based nanofluid cutting fluid of the present invention is simple and the comprehensive cost is low. The present invention adopts in-situ graphite exfoliation and dispersion to prepare the graphene-based cutting fluid, which can significantly reduce the preparation cost of the graphene-based cutting fluid. In addition, the preparation process has the remarkable characteristics of mild process conditions, reuse of raw materials, and no generation of three wastes in the process.

[0026] 5. The graphene-based nanofluid cutting fluid of the present invention has a long service life. Since the content of organic components in the cutting fluid is low and graphene has a bactericidal function, the cutting fluid of the present invention can be reused without regular failure treatment. The product prepared by this technology has been evaluated by industrial application and its service life is at least two years. The cutting fluid commonly used in industry generally needs to be replaced every 1-3 months. Therefore, the use of the product of the present invention reduces the replacement frequency by 80% to 95% compared with the current product, thus producing significant energy saving, emission reduction and consumption reduction effects.

[0027] 6. The graphene-based nanofluid cutting fluid of the present invention is applicable to a wide range of processing occasions. In addition to general occasions, it still shows excellent applicability in metal cutting processes under extreme and harsh conditions.

[0028] Of course, any product implementing the present invention does not necessarily need to achieve all of the above advantages at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a comparison chart of the change of the friction coefficient of the cutting fluid of Examples 1-4 and Comparative Example 1;

[0031] Figure 2 A comparison diagram of the wear scar diameter of the cutting fluid of Examples 1-4 and Comparative Example 1;

[0032] Figure 3 It is a comparison chart of the friction coefficient of the product of Example 4 and the industrial cutting fluid over time;

[0033] Figure 4 This is a comparison chart of the temperature rise data of the product of Example 4 and the reference product during the long-term friction process;

[0034] Figure 5 This is a graph showing the stability evaluation results of the graphene-based nanofluid cutting fluid of Example 4;

[0035] Figure 6 This is a comparison chart of the friction coefficient of multiple cycle tests of Example 4;

[0036] Figure 7 The figure is a comparison chart of the change in friction diameter of the product of Example 4 during ten cycles of use and the comparison chart with the control product. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Evaluation of the stability of graphene-based nanofluid cutting fluid: Gravity sedimentation observation method was used for evaluation;

[0039] The cutting performance of graphene-based nanofluid cutting fluid was evaluated using a four-ball friction tester, and the main evaluation indicators were friction coefficient and wear scar diameter.

[0040] Example 1

[0041] This embodiment provides a method for preparing a graphene-based nanofluid cutting fluid, comprising the following steps:

[0042] 1) adding xanthan gum (1.0 wt.%) as a dispersant and sodium alginate (0.01 wt.%) as an auxiliary dispersant into water, mixing and dissolving to prepare an auxiliary agent solution for later use;

[0043] 2) mixing graphite and exfoliation aid solution in a mass ratio of 1:100 and ultrasonicating at a power of 300 W for 60 min to obtain a graphite dispersion;

[0044] 3) Add the uniformly dispersed graphite dispersion into the hydroxyl radical reactor, control the temperature at 20°C, the air flow rate at 1.0 L / h, the current at 5 A, and centrifuge the reaction liquid after 3 hours to obtain the upper layer of graphene-based nanofluid cutting fluid. The solid after centrifugation is used for the next cutting fluid preparation.

[0045] Example 2

[0046] This embodiment provides a method for preparing a graphene-based nanofluid cutting fluid, comprising the following steps:

[0047] 1) adding dispersant xanthan gum (1 wt.%) and co-dispersant PEG400 (0.01 wt.%) into water, mixing and dissolving to prepare a dispersant solution for later use;

[0048] 2) mixing graphite and exfoliation aid solution in a mass ratio of 1:100 and ultrasonicating at a power of 300 W for 60 min to obtain a graphite dispersion;

[0049] 3) The uniformly dispersed graphite dispersion is placed in a hydroxyl radical reactor, the temperature is controlled at 20°C, the air flow rate is 1.0 L / h, the current is 5A, and the reaction liquid is centrifuged after the reaction time is 3 hours. The upper layer liquid is obtained as the graphene-based nanofluid cutting fluid, and the solid after centrifugation is used for the next cutting fluid preparation.

[0050] Example 3

[0051] This embodiment provides a method for preparing a graphene-based nanofluid cutting fluid, comprising the following steps:

[0052] 1) adding dispersant xanthan gum (1.0 wt.%) and dispersant sodium dodecylbenzene sulfonate (0.01 wt.%) into water, mixing and dissolving to prepare an auxiliary agent solution for use;

[0053] 2) Mixing the expanded graphite and the stripping aid solution in a mass ratio of 1:100 and ultrasonicating at a power of 300 W for 60 min to obtain an expanded graphite dispersion;

[0054] 3) Add the uniformly dispersed graphite dispersion into the hydroxyl radical reactor, control the temperature at 20°C, the air flow rate at 1.0 L / h, the current at 5 A, and centrifuge the reaction liquid after 3 hours to obtain the upper layer of graphene-based nanofluid cutting fluid. The solid after centrifugation is used for the next cutting fluid preparation.

[0055] Example 4

[0056] This embodiment provides a method for preparing a graphene-based nanofluid cutting fluid, comprising the following steps:

[0057] 1) adding dispersant xanthan gum (1.0 wt.%) and co-dispersant Tween 80 (0.01 wt.%) into water, mixing and dissolving to prepare a dispersant solution for later use;

[0058] 2) mixing the expanded graphite and the stripping aid solution in a mass ratio of 1:100 and ultrasonicating at a power of 300 W for 60 min to obtain a dispersion;

[0059] 3) Add the dispersion into the hydroxyl radical reactor, control the temperature at 20°C, the air flow rate at 1.0 L / h, the current at 5 A, and centrifuge the reaction liquid after 3 hours to obtain the upper layer of graphene-based nanofluid cutting fluid. The solid after centrifugation can be used as a raw material in the next cutting fluid preparation.

[0060] Example 5

[0061] This embodiment provides a method for preparing a graphene-based nanofluid cutting fluid. This embodiment is basically the same as Example 4, except that polyethylene oxide is used as the dispersant instead of xanthan gum.

[0062] Example 6

[0063] This embodiment provides a method for preparing a graphene-based nanofluid cutting fluid. This embodiment is basically the same as Example 4, except that sodium pentosan sulfate is used as the raw material instead of xanthan gum.

[0064] Comparative Example 1

[0065] In this comparative example, the cutting fluid is a cutting fluid widely used in industry, and its specific model is 3401-AD01.

[0066] The long-term friction performance test of the cutting fluids of Example 4 and Comparative Example 1 was conducted on a four-ball friction tester at 3500 min. The friction coefficient and the temperature rise of the cutting fluids of Example 4 and Comparative Example 1 were mainly compared. Figure 3 and Figure 4 The results show that the cutting fluid prepared in Example 4 has better lubrication ability and heat dissipation effect on the tool and workpiece than that in Comparative Example 1.

[0067] The graphene-based nanofluid cutting fluid prepared in Example 4 was tested for stability and rheological properties in cutting applications. Figure 5 The stability test results of graphene-based nanofluid cutting fluid are shown in Figure 2. Figure 6 These are the test results of the usage time and performance of graphene-based nanofluid cutting fluid in industrial applications.

[0068] The products in each embodiment were compared with the cutting fluid widely used in industry for application performance. The friction coefficient test results are shown in Figure 1, the wear scar diameter test results are shown in Figure 2 .

[0069] from Figure 1 It can be seen that the friction coefficient of the product of the present invention is stable at about 0.05 throughout the friction test.

[0070] The friction coefficient of the industrial cutting fluid of Comparative Example 1 is basically maintained at 0.07, which is about 30% higher than that of the product of the present invention. Therefore, the cutting fluid of the present invention has a better friction reduction effect.

[0071] Figure 2 The wear scar diameters of the industrial cutting fluid and the product of the present invention are compared. It can be clearly seen from the figure that under the same cutting force, the wear scar diameters (0.28-0.45mm) of the products of each embodiment are smaller than the cutting diameter (0.5mm) of the industrial cutting fluid product, which further proves that the friction reduction effect of the cutting fluid of the present invention is better than that of the industrial product.

[0072] To further confirm the excellent performance of the cutting fluid product provided in Example 4, an experiment on the maximum cutting load was carried out according to the national standard GB / T3142-2019. The results showed that while meeting the requirements of the national standard, the maximum load of the cutting fluid in Example 4 was 922N, while the maximum load of the corresponding industrial product was only 498N. This shows that the cutting fluid product can adapt to processes under heavy cutting forces.

[0073] In order to evaluate the long-term performance of this product and industrial reference products, an experiment on the change of friction coefficient and cutting fluid temperature rise during long-term cutting was carried out. The results are as follows: Figure 3 and Figure 4 shown. Figure 3 It can be seen that as the friction time increases, the friction coefficient of comparative example 1 is around 0.07, but there is a significant fluctuation. The friction coefficient of the product of Example 4 is 0.05, maintaining good stability. This shows that the cutting fluid of this product has good stability and lubrication performance. Figure 4 It can be seen that during the long-term cutting process, the temperature rise of the product of Example 4 is 29.3% higher than that of the comparative example 1, indicating that the product of the present invention has better thermal conductivity than the reference product, which is beneficial for protecting the tool from the harm caused by overheating.

[0074] In view of the important influence of nanofluid stability on performance, the long-term storage stability of this product was evaluated. Figure 5 As shown, the nanofluid showed no obvious agglomeration after being placed for two years, indicating that the nanofluid has excellent stability.

[0075] Considering the significant influence of the service life of the cutting fluid on the process economy and environmental performance, the experimental study on the change of the friction coefficient during the recycling process of the product of the present invention was conducted. The results showed that after ten cycles, the friction coefficient was maintained between 0.05 and 0.06, and the wear scar diameter was less than 0.32 mm. After the control product was recycled for 4 times, the wear scar diameter exceeded 0.32 mm; after 10 cycles, the friction coefficient increased to 0.15, and the wear scar diameter reached 0.426 nm (the standard value is 0.32 mm). Therefore, the cutting fluid of the present invention has a more excellent recycling performance.

[0076] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a graphene-based nanofluid cutting fluid, characterized in that: The steps include: 1) Mixing and dissolving the dispersant and the dispersing aid in water to obtain a stripping aid solution; The dispersant is at least one of xanthan gum, carboxymethyl chitosan, sodium pentosan sulfate, sodium cellulose acetate, sodium polystyrene sulfonate, and polyethylene oxide; The dispersing aid is at least one of sodium alginate, PEG-400, PEG-200, Tween 80 and Tween 60; 2) After mixing graphite or expanded graphite and a solution of an exfoliating agent, a dispersion of graphite or expanded graphite is obtained by ultrasonic pre-dispersion; 3) The graphite dispersion is subjected to exfoliation reaction and centrifugal separation by a hydroxyl radical generator, and the upper layer of liquid is taken after the centrifugation, and the upper layer of liquid is the graphene-based nanofluid cutting fluid.

2. The method for preparing a graphene-based nanofluid cutting fluid according to claim 1, characterized in that: In step 2), the mass ratio of graphite or expanded graphite to the stripping agent solution is 0.0001-0.

05.

3. The method for preparing the graphene-based nanofluid cutting fluid according to claim 1, characterized in that: In step 2), the graphite or expanded graphite is mixed with the stripping agent solution by ultrasonic dispersion, with an ultrasonic power of 200-700 W and an ultrasonic time of 30-120 min.

4. The method for preparing the graphene-based nanofluid cutting fluid according to claim 1, characterized in that: In step 3), the preparation reaction conditions of the graphene-based nanofluid cutting fluid are: temperature 20-40° C., air flow rate 0.5-10 L / h, current 1-20 A, and time 0.5-6 h.

5. The method for preparing the graphene-based nanofluid cutting fluid according to claim 1, characterized in that: In step 3), during the preparation of the graphene-based nanofluid cutting fluid, the centrifugal speed is 3000-8000 rpm and the time is 10-60 min.

6. The method for preparing the graphene-based nanofluid cutting fluid according to claim 1, characterized in that: In step 3), the solid separated from the reaction system for preparing the graphene-based nanofluid cutting fluid is used as a raw material for preparing the next graphene-based nanofluid cutting fluid.

7. A graphene-based nanofluid cutting fluid prepared by the method for preparing the graphene-based nanofluid cutting fluid according to any one of claims 1 to 6.

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