A black phosphorus quantum dot water-based lubricant additive and its preparation method

Abstract

The present invention provides a black phosphorus quantum dot water-based lubricating additive and a preparation method, comprising: step one, using black phosphorus powder as a raw material, and then adding lactic acid to the black phosphorus powder for ball milling. Step two, centrifuging and washing the ball-milled material obtained in step one with deionized water, and taking the supernatant. Step three, high-speed centrifuging the supernatant obtained in step two, taking the precipitate to obtain a black phosphorus quantum dot water-based lubricating additive modified with lactic acid. The friction coefficient of the black phosphorus quantum dot water-based lubricating additive is initially reduced to below 0.1 within 3 seconds, and the stable friction coefficient is less than about 0.017 to 0.019. The present invention modifies the black phosphorus quantum dots while preparing them, breaking the previous inherent process of first preparing the black phosphorus quantum dots and then modifying them. The present invention can improve the problems of high preparation cost, complex manufacturing process, and unstable lubrication effect of existing black phosphorus quantum dot lubricating additives. The preparation process of the present invention is more convenient, more efficient, and environmentally friendly and pollution-free.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials and relates to lubricating additives, in particular to a black phosphorus quantum dot water-based lubricating additive and a preparation method thereof. Background Art

[0002] Friction is ubiquitous and essential in our lives, but some friction is unnecessary or even harmful. For example, friction and wear in mechanical components is a major cause of energy dissipation and component failure. Reducing this harmful friction has a significant impact on energy, the environment, technology, and the economy worldwide. Over the past few decades, efforts have been made to reduce friction and wear, and many effective lubricant materials have been discovered, such as graphene oxide, hexagonal boron nitride, and molybdenum disulfide. In recent years, a new material, black phosphorus quantum dots (BPQDs), has attracted widespread attention from researchers at home and abroad due to its low friction coefficient and minimal wear rate.

[0003] At present, it has been found in the process of widespread application that although black phosphorus quantum dots have a low friction coefficient, it takes a long running-in period to have a low friction coefficient. In the initial stage of friction, the friction coefficient of black phosphorus quantum dots is relatively high and cannot meet the requirements of some specific working conditions.

[0004] Meanwhile, existing processes for modifying and modifying black phosphorus quantum dots involve first preparing large black phosphorus particles into black phosphorus quantum dots, then modifying them using various methods. These methods are typically time-consuming, energy-intensive, cumbersome, and complex, resulting in high costs and low yields. Furthermore, the resulting black phosphorus quantum dots are prone to degradation, limiting their further development and application.

[0005] Therefore, the main problems currently exist are: 1) The lubrication properties of black phosphorus quantum dots need to be improved to achieve a low friction coefficient even at the initial stage of friction. 2) Existing modified black phosphorus quantum dot lubricant additives require the preparation of large-scale black phosphorus powder into black phosphorus quantum dots before modification, which is costly and complex. A new, simpler and more convenient preparation process is needed to produce modified black phosphorus quantum dots in a single step. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a black phosphorus quantum dot water-based lubricating additive and a preparation method to solve the technical problem that the friction coefficient of the lubricating additive in the existing technology needs to be further reduced.

[0007] The present invention also provides a method for preparing a black phosphorus quantum dot water-based lubricating additive, which solves the technical problem in the prior art that it is difficult to modify the black phosphorus quantum dots while preparing them.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] A method for preparing a black phosphorus quantum dot water-based lubricating additive, the method comprising the following steps:

[0010] In step 1, black phosphorus powder is used as the raw material, and then lactic acid is added to the black phosphorus powder for ball milling.

[0011] Step 2: The ball-milled material obtained in step 1 is centrifuged and washed with deionized water, and the supernatant is collected.

[0012] Step 3: high-speed centrifuge the supernatant obtained in step 2, and take the precipitate to obtain the lactic acid-modified black phosphorus quantum dot water-based lubricating additive.

[0013] The present invention also has the following technical features:

[0014] In step 1, the mass concentration of the lactic acid aqueous solution is above 75%, and the particle size of the black phosphorus powder is 100 nm to 10 μm.

[0015] In step 1, the mass ratio of the lactic acid aqueous solution to the black phosphorus powder is (100-200):1.

[0016] In step 1, the ball-to-material mass ratio of the ball mill is (2-10):1, the ball mill speed is above 300 rpm, and the ball milling time is above 10 hours.

[0017] Preferably, in step 1, the ball milling speed is 300 to 600 rpm, and the ball milling time is 12 to 36 hours.

[0018] In step 2, the centrifugal speed is 3000-5000 rpm and the centrifugal time is 10 min, the purpose of which is to remove large particle sediments.

[0019] In step three, the high-speed centrifugation speed is 8000-11000 rpm and the time is 15-20 min, the purpose of which is to separate the modified black phosphorus quantum dots from the lactic acid dissolved in water and precipitate the modified black phosphorus quantum dots.

[0020] The present invention also protects a black phosphorus quantum dot water-based lubricating additive, which is prepared by the above-mentioned preparation method of the black phosphorus quantum dot water-based lubricating additive.

[0021] The friction coefficient of the black phosphorus quantum dot water-based lubricating additive is initially reduced to below 0.1 within 3 seconds, and the stable friction coefficient is less than about 0.017 to 0.019.

[0022] The surface of the black phosphorus quantum dots in the black phosphorus quantum dot water-based lubricating additive is modified with lactic acid, and has HO-P=O bonds, P=O bonds and P-OH bonds.

[0023] The black phosphorus quantum dot water-based lubricating additive can be stably dispersed in a solution, and has a particle size of 1 to 12 nm.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] (I) The preparation method of the present invention modifies black phosphorus quantum dots while preparing them, breaking the traditional inherent process of first preparing black phosphorus quantum dots and then modifying them.

[0026] (II) The preparation method of the present invention comprises ball-milling lactic acid and black phosphorus quantum dots together to obtain a product with a particle diameter of about 1 nm to 12 nm. The obtained black phosphorus quantum dots are modified to obtain P-OH bonds and HO-P=O bonds. The black phosphorus quantum dots are modified while being prepared.

[0027] (III) The preparation method of the present invention can improve the problems of high preparation cost, complex production process and unstable lubrication effect of existing black phosphorus quantum dot lubricant additives. The preparation process of the present invention is more convenient, more efficient, and environmentally friendly and pollution-free.

[0028] (IV) The black phosphorus quantum dot water-based lubricating additive of the present invention can reduce the friction coefficient at the initial stage of friction and has good lubrication performance. The friction coefficient added to the aqueous solution is lower than that of the lactic acid aqueous solution or the pure black phosphorus quantum dot aqueous solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a TEM image of the product of Example 1, and the particle size is about 2-5 nm.

[0030] Figure 2 This is the Raman spectrum of the product in Example 1.

[0031] Figure 3 This is a Fourier transform infrared spectrum picture of the product in Example 1.

[0032] Figure 4 The friction coefficients of Example 1, Comparative Example 1, and Comparative Example 2 are compared, and are reduced by 48.3% and 85.41% respectively.

[0033] The specific contents of the present invention are further explained in detail below with reference to the embodiments. DETAILED DESCRIPTION

[0034] It should be noted that, unless otherwise specified, all raw materials used in the present invention are raw materials known in the prior art.

[0035] In accordance with the above technical solution, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0036] Example 1:

[0037] This embodiment provides a method for preparing a black phosphorus quantum dot water-based lubricating additive, which comprises the following steps:

[0038] Step 1: Weigh 0.2g of black phosphorus powder and place it in a clean polytetrafluoroethylene ball mill. Weigh 100g of agate balls, half of which are ф10nm and half of which are ф5nm, and place them in the mill. Weigh 20g of lactic acid aqueous solution and place them in the mill as well. The rotation speed is 400rpm, and the milling time is 1440min, with a 30min pause every 60min. After the milling time is completed, remove the mill and place it at room temperature for 720min. Remove the liquid inside to obtain the prepared solution containing impurities such as agate ball chips, polytetrafluoroethylene chips, and large pieces of black phosphorus powder.

[0039] In this step, the mass concentration of the lactic acid aqueous solution is 85%, and the particle size of the black phosphorus powder is 100 nm to 10 μm.

[0040] Step 2: Place the impurity-containing solution prepared in step 1 into a centrifuge at a speed of 4000 rpm for 10 minutes, and take the supernatant after centrifugation.

[0041] Step 3: continue to high-speed centrifuge the supernatant obtained in step 2 at a centrifuge speed of 10,000 rpm for 20 minutes, and take the precipitate to obtain a lactic acid-modified black phosphorus quantum dot water-based lubricating additive.

[0042] The particle size of the black phosphorus quantum dot water-based lubricating additive prepared in this embodiment is about 2 to 5 nm. The microscopic picture is as follows: Figure 1 shown.

[0043] The lactic acid modified black phosphorus quantum dots prepared in this example were tested by Raman spectroscopy, and characteristic peaks appeared, which can prove that the prepared quantum dots are black phosphorus quantum dots. Figure 2 shown.

[0044] The infrared absorption spectrum test of the lactic acid modified black phosphorus quantum dots prepared in this example shows HO-P=O bond, P=O bond and P-OH bond, which proves that the black phosphorus quantum dots are successfully modified with lactic acid. Figure 3 shown.

[0045] The black phosphorus quantum dot water-based lubricating additive prepared in this embodiment was added to deionized water at a mass ratio of 10:90, and ultrasonically dispersed for 10 minutes. The friction coefficient of the lubricating fluid was tested. The test showed that the black phosphorus quantum dot water-based lubricating additive prepared in this embodiment was uniformly dispersed in the aqueous solution, and the friction coefficient dropped to below 0.1 within the initial 3 seconds, and the stable friction coefficient was less than about 0.017. Figure 4 shown.

[0046] Example 2:

[0047] This embodiment provides a method for preparing a black phosphorus quantum dot water-based lubricating additive, which comprises the following steps:

[0048] Step 1: Weigh 0.1g of black phosphorus powder and place it in a clean polytetrafluoroethylene ball mill. Weigh 100g of agate balls, half of which are ф10nm and half of which are ф5nm, and place them in the ball mill. Weigh 20g of lactic acid aqueous solution and place them in the same ball mill. The rotation speed is 400rpm, the ball milling time is 1440min, and the ball milling time is 30min after every 60min of ball milling. After the ball milling time is completed, remove the ball mill and place it at room temperature for 720min. The liquid inside is taken out to obtain the lactic acid-modified black phosphorus quantum dot water-based lubricating additive containing impurities such as agate ball chips, polytetrafluoroethylene waste chips, and large pieces of black phosphorus powder.

[0049] In this step, the mass concentration of the lactic acid aqueous solution is 85%, and the particle size of the black phosphorus powder is 100 nm to 10 μm.

[0050] Step 2: Place the impurity-containing solution prepared in step 1 into a centrifuge at a speed of 4000 rpm for 10 minutes, and take the supernatant after centrifugation.

[0051] Step 3: continue to high-speed centrifuge the supernatant obtained in step 2 at a centrifuge speed of 10,000 rpm for 20 minutes, and take the precipitate to obtain a lactic acid-modified black phosphorus quantum dot water-based lubricating additive.

[0052] The performance test results of the black phosphorus quantum dot water-based lubricating additive prepared in this example are similar to those of Figures 1 to 3 The performance test results of Example 1 are similar and will not be repeated here.

[0053] The black phosphorus quantum dot water-based lubricant additive prepared in this example was added to deionized water at a mass ratio of 10:90 and ultrasonically dispersed for 10 minutes to obtain a lactic acid-modified black phosphorus quantum dot water-based lubricant additive. Testing showed that the lactic acid-modified black phosphorus quantum dots dispersed evenly in the aqueous solution, with the friction coefficient dropping below 0.1 within the initial 3 seconds and maintaining a stable friction coefficient of approximately 0.019.

[0054] Example 3:

[0055] This embodiment provides a method for preparing a black phosphorus quantum dot water-based lubricating additive, which comprises the following steps:

[0056] Step 1: Weigh 0.2g of black phosphorus powder and place it in a clean polytetrafluoroethylene ball mill. Weigh 100g of agate balls, half of which are ф10nm and half of which are ф5nm, and place them in the ball mill. Weigh 20g of lactic acid aqueous solution and place them in the same ball mill. The rotation speed is 400rpm, and the ball milling time is 1080min. After every 60min of ball milling, stop for 30min. After the ball milling time is completed, remove the ball mill and place it at room temperature for 720min. The liquid inside is taken out to obtain the lactic acid-modified black phosphorus quantum dot water-based lubricating additive containing impurities such as agate ball chips, polytetrafluoroethylene waste chips, and large pieces of black phosphorus powder.

[0057] In this step, the mass concentration of the lactic acid aqueous solution is 85%, and the particle size of the black phosphorus powder is 100 nm to 10 μm.

[0058] Step 2: Place the impurity-containing solution prepared in step 1 into a centrifuge at a speed of 4000 rpm for 10 minutes, and take the supernatant after centrifugation.

[0059] Step 3: continue to high-speed centrifuge the supernatant obtained in step 2 at a centrifuge speed of 10,000 rpm for 20 minutes, and take the precipitate to obtain a lactic acid-modified black phosphorus quantum dot water-based lubricating additive.

[0060] The performance test results of the black phosphorus quantum dot water-based lubricating additive prepared in this example are similar to those of Figures 1 to 3 The performance test results of Example 1 are similar and will not be repeated here.

[0061] The black phosphorus quantum dot water-based lubricant additive prepared in this example was added to deionized water at a mass ratio of 10:90 and ultrasonically dispersed for 10 minutes to obtain a lactic acid-modified black phosphorus quantum dot water-based lubricant additive. Testing showed that the lactic acid-modified black phosphorus quantum dots dispersed evenly in the aqueous solution, with the friction coefficient dropping below 0.1 within the initial 3 seconds and maintaining a stable friction coefficient of approximately 0.017.

[0062] Example 4:

[0063] This embodiment provides a method for preparing a black phosphorus quantum dot water-based lubricating additive, which comprises the following steps:

[0064] Step 1: Weigh 0.2g of black phosphorus powder and place it in a clean polytetrafluoroethylene ball mill. Weigh 100g of agate balls, half of which are ф10nm and half of which are ф5nm, and place them in the ball mill. Weigh 20g of lactic acid aqueous solution and place them in the same ball mill. The rotation speed is 600rpm, and the ball milling time is 1440min. Stop for 30min every 60min of ball milling. After the ball milling time is completed, remove the ball mill and place it at room temperature for 720min. The liquid inside is taken out to obtain the lactic acid-modified black phosphorus quantum dot water-based lubricating additive containing impurities such as agate ball chips, polytetrafluoroethylene waste chips, and large pieces of black phosphorus powder.

[0065] In this step, the mass concentration of the lactic acid aqueous solution is 85%, and the particle size of the black phosphorus powder is 100 nm to 10 μm.

[0066] Step 2: Place the impurity-containing solution prepared in step 1 into a centrifuge at a speed of 4000 rpm for 10 minutes, and take the supernatant after centrifugation.

[0067] Step 3: continue to high-speed centrifuge the supernatant obtained in step 2 at a centrifuge speed of 10,000 rpm for 20 minutes, and take the precipitate to obtain a lactic acid-modified black phosphorus quantum dot water-based lubricating additive.

[0068] The performance test results of the black phosphorus quantum dot water-based lubricating additive prepared in this example are similar to those of Figures 1 to 3 The performance test results of Example 1 are similar and will not be repeated here.

[0069] The black phosphorus quantum dot water-based lubricant additive prepared in this example was added to deionized water at a mass ratio of 10:90 and ultrasonically dispersed for 10 minutes to obtain a lactic acid-modified black phosphorus quantum dot water-based lubricant additive. Testing showed that the lactic acid-modified black phosphorus quantum dots dispersed evenly in the aqueous solution, with the friction coefficient dropping below 0.1 within the initial 3 seconds and maintaining a stable friction coefficient of approximately 0.017.

[0070] Comparative Example 1: (Raw Material Comparison)

[0071] This comparative example provides a method for preparing an unmodified black phosphorus quantum dot water-based lubricating additive, which comprises the following steps:

[0072] Step 1: Weigh 0.4g of black phosphorus powder and place it in 20ml of N-methylpyrrolidone (NMP). Ultrasonicate the powder for 6 hours, sonicating for 3 seconds and stopping for 1.5 seconds. The resulting liquid after sonication is a solution of black phosphorus quantum dots dispersed in NMP.

[0073] Step 2: Place the solution obtained in step 1 into a centrifuge at a speed of 4500 rpm for 10 minutes. After centrifugation, the solution is precipitated as large black phosphorus nanosheets that are not completely crushed. Take the supernatant and continue high-speed centrifugation at a speed of 10000 rpm for 20 minutes to obtain black phosphorus quantum dots containing NMP.

[0074] Step 3: Add the precipitate obtained in step 2 to deionized water for washing, add 40 ml of ultrapure water and continue high-speed centrifugation at a centrifuge speed of 10,000 rpm for 20 minutes, take the precipitate, repeat two to three times, and take the precipitate, which is the unmodified black phosphorus quantum dot water-based lubricating additive.

[0075] The unmodified black phosphorus quantum dot water-based lubricating additive prepared in this comparative example was added to deionized water at a mass ratio of 10:90 and ultrasonically dispersed for 10 minutes to obtain a black phosphorus quantum dot water-based solution. The test showed that the prepared black phosphorus quantum dots were evenly dispersed in the aqueous solution. The friction coefficient fluctuated violently between 0.1 and 0.25 in the early stage, and was basically stable after 6 minutes. The average friction coefficient was about 0.09, and was about 0.03 after stabilization. Figure 4 As shown, when comparing the friction coefficients of Example 1 with those of Comparative Example 1, the friction coefficient of Example 1 is reduced by 48.3%. In addition, the running-in time of Comparative Example 1 is long, the friction coefficient in the early stage is huge, and the fluctuation is obvious.

[0076] Comparative Example 2: (Raw Material Comparison)

[0077] This comparative example provides a lactic acid aqueous solution with a mass concentration of 85%. As a blank control group experiment, the friction coefficient is always unstable and fluctuates violently. The average friction coefficient is about 0.11. Figure 4 As shown, the friction coefficient of Example 1 is compared with that of Comparative Example 1, and the friction coefficient of Example 1 is reduced by 85.41%. In addition, the friction coefficient of Comparative Example 2 fluctuates in the later stage, and the overall friction coefficient is high.

[0078] Comparative Example 3: (Comparison of raw material dosage)

[0079] This comparative example provides a method for preparing a lactic acid-modified black phosphorus quantum dot water-based lubricating additive. The preparation method of this comparative example is the same as the main process of the preparation method of Example 1. The only difference is that in this comparative example, the mass ratio of the lactic acid aqueous solution to the black phosphorus powder in step 1 is changed to 50:1, that is, the lactic acid aqueous solution in this comparative example is 10g.

[0080] The particle size of the lactic acid-modified black phosphorus quantum dot water-based lubricating additive obtained in this comparative example is about 5-80 nm.

[0081] The lactic acid-modified black phosphorus quantum dot water-based lubricant obtained in this comparative example was added to deionized water at a mass ratio of 10:90 and ultrasonically dispersed for 10 minutes. The friction coefficient of the lubricant was then tested. The results showed that the lactic acid-modified black phosphorus quantum dots dispersed evenly in the aqueous solution. While the friction coefficient fluctuated dramatically initially, it stabilized after approximately 6 minutes, reaching a stable friction coefficient of approximately 0.023.

[0082] Comparative Example 4: (Comparison of raw material dosage)

[0083] This comparative example provides a method for preparing a lactic acid-modified black phosphorus quantum dot water-based lubricating additive. The main process of this method is the same as the preparation method of Example 1. The only difference is that in this comparative example, the mass ratio of the lactic acid aqueous solution to the black phosphorus powder in step 1 is changed to 300:1, that is, the lactic acid aqueous solution in this comparative example is 60g.

[0084] The lactic acid-modified black phosphorus quantum dot water-based lubricating additive obtained in this comparative example has a particle size of about 2-23 nm.

[0085] The lactic acid-modified black phosphorus quantum dot water-based lubricant obtained in this comparative example was added to deionized water at a mass ratio of 10:90 and ultrasonically dispersed for 10 minutes. The friction coefficient of the lubricant was then tested. The results showed that the lactic acid-modified black phosphorus quantum dots dispersed evenly in the aqueous solution, maintaining a relatively flat friction coefficient of approximately 0.03.

[0086] Comparative Example 5: (Ball Milling Time Comparison)

[0087] This comparative example provides a method for preparing a lactic acid-modified black phosphorus quantum dot water-based lubricating additive. The preparation method of this comparative example is the same as the main process of the preparation method of Example 1, with the only difference being that the total ball milling time in step 1 is changed to 480 min in this comparative example.

[0088] The particle size of the lactic acid-modified black phosphorus quantum dot water-based lubricating additive obtained in this comparative example is about 30-200 nm.

[0089] The lactic acid-modified black phosphorus quantum dot water-based lubricant obtained in this comparative example was added to deionized water at a mass ratio of 10:90 and ultrasonically dispersed for 10 minutes. The friction coefficient of the lubricant was then tested. The lactic acid-modified black phosphorus quantum dots dispersed evenly in the aqueous solution, with the friction coefficient fluctuating wildly before gradually stabilizing after 5 minutes, reaching a stable friction coefficient of approximately 0.093.

[0090] Comparative Example 6: (Comparison of ball mill speed)

[0091] This comparative example provides a method for preparing a lactic acid-modified black phosphorus quantum dot water-based lubricating additive. The preparation method of this comparative example is the same as the main process of the preparation method of Example 1, with the only difference being that the ball milling speed in step 1 is changed to 200 rpm in this comparative example.

[0092] The lactic acid-modified black phosphorus quantum dot water-based lubricating additive obtained in this comparative example has a particle size of about 70-300 nm.

[0093] The lactic acid-modified black phosphorus quantum dot water-based lubricant obtained in this comparative example was added to deionized water at a mass ratio of 10:90 and ultrasonically dispersed for 10 minutes. The friction coefficient of the lubricant was then tested. The lactic acid-modified black phosphorus quantum dots dispersed evenly in the aqueous solution, with the friction coefficient fluctuating wildly before gradually stabilizing after about 5 minutes, reaching a stable friction coefficient of approximately 0.036.

[0094] Comparative Example 7: (Comparison of initial centrifugal speed)

[0095] This comparative example provides a method for preparing a lactic acid-modified black phosphorus quantum dot water-based lubricating additive. The preparation method of this comparative example is the same as the main process of the preparation method of Example 1, with the only difference being that the centrifugal speed in step 2 is set to 1500 rpm in this comparative example, that is, the initial centrifugal speed is set to 1500 rpm.

[0096] The lactic acid-modified black phosphorus quantum dot water-based lubricant obtained in this comparative example was added to deionized water at a mass ratio of 10:90 and ultrasonically dispersed for 10 minutes. The friction coefficient of the lubricant was then tested. The results showed that the lactic acid-modified black phosphorus quantum dots dispersed evenly in the aqueous solution, while the friction coefficient fluctuated significantly, with an average coefficient of approximately 0.33.

[0097] Comparative Example 8: (Comparison without secondary centrifugation)

[0098] This comparative example provides a method for preparing a lactic acid-modified black phosphorus quantum dot water-based lubricating additive. The preparation method of this comparative example is the same as the main process of the preparation method of Example 1, with the only difference being that there is no centrifugation operation in step three of this comparative example, i.e., no secondary centrifugation.

[0099] The lactic acid-modified black phosphorus quantum dot water-based lubricant obtained in this comparative example was added to deionized water at a mass ratio of 10:90 and ultrasonically dispersed for 10 minutes. The friction coefficient of the lubricant was then tested. The lactic acid-modified black phosphorus quantum dots dispersed evenly in the aqueous solution, with some fluctuations in the friction coefficient, which gradually stabilized after approximately 4 minutes, reaching an average friction coefficient of approximately 0.27.

Claims

1. A black phosphorus quantum dot water-based lubricating additive, characterized in that: The preparation method of the black phosphorus quantum dot water-based lubricating additive comprises the following steps: Step 1: Black phosphorus powder is used as the raw material, and then lactic acid is added to the black phosphorus powder for ball milling; In step 1, the mass concentration of the lactic acid aqueous solution is greater than 75%, and the particle size of the black phosphorus powder is 100 nm to 10 μm; In step 1, the mass ratio of the lactic acid aqueous solution to the black phosphorus powder is (100-200):1; In step 1, the ball-to-material mass ratio of the ball milling is (2-10):1, the ball milling speed is above 300 rpm, and the ball milling time is above 10 h; In step 1, the ball milling speed is 300 to 600 rpm, and the ball milling time is 12 to 36 hours; Step 2: centrifuge and wash the ball-milled material obtained in step 1 with deionized water, and collect the supernatant; In step 2, the centrifugal speed is 3000-5000 rpm and the centrifugal time is 10 min; Step 3, high-speed centrifuging the supernatant obtained in step 2, and taking the precipitate to obtain a lactic acid-modified black phosphorus quantum dot water-based lubricating additive; In step 3, the high-speed centrifugation speed is 8000-11000 rpm, and the time is 15-20 min; The friction coefficient of the black phosphorus quantum dot water-based lubricating additive is initially reduced to below 0.1 within 3 seconds, and the stable friction coefficient is less than 0.017 to 0.019; The surface of the black phosphorus quantum dots in the black phosphorus quantum dot water-based lubricating additive is modified with lactic acid, and there are HO-P=O bonds, P=O bonds and P-OH bonds; The black phosphorus quantum dot water-based lubricating additive can be stably dispersed in a solution, and has a particle size of 1 to 12 nm.

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