阅读说明：本技术 一种BN/Cu/PDA纳米复合微粒及其制备方法和应用 (BN/Cu/PDA nano composite particles and preparation method and application thereof ) 是由 贾正锋 臧超 韩潍坊 钱秋花 刘二波 赵加欢 张博 张拓 赵鹏 杨婷婷 滕琪 于 2021-10-25 设计创作，主要内容包括：本发明涉及纳米复合材料技术领域,具体涉及一种BN/Cu/PDA纳米复合微粒及其制备方法和应用。本发明提供的BN/Cu/PDA纳米复合微粒,其组成中BN:Cu:DA的比例关系为：1-3：0.5-2：1-4,其粒径范围为20-100nm,磨斑直径为0.38-0.63mm,摩擦系数为0.041-0.077。本制备方法工序简单,无需使用现有制备方法常用的高温、高压等复杂操作,具有绿色环保的优点,使用到的原料简单易得,便于规模化生产；通过制备方法制得的BN/Cu/PDA纳米复合微粒粒径为纳米级,作为添加剂加入润滑油中能使润滑油获得良好的减摩耐磨性能。(The invention relates to the technical field of nano composite materials, in particular to BN/Cu/PDA nano composite particles and a preparation method and application thereof. The BN/Cu/PDA nano composite particles provided by the invention have the following composition proportion relation of BN to Cu to DA: 1-3:0.5-2:1-4, the particle size range of which is 20-100nm, the diameter of the abrasion spot is 0.38-0.63mm, and the friction coefficient is 0.041-0.077. The preparation method has simple process, does not need to use the complex operations of high temperature, high pressure and the like commonly used in the existing preparation method, has the advantage of environmental protection, uses simple and easily obtained raw materials, and is convenient for large-scale production; the BN/Cu/PDA nano composite particles prepared by the preparation method have a nano-scale particle size, and can be used as an additive to be added into lubricating oil to enable the lubricating oil to obtain good antifriction and wear-resistant performances.)

1. The nanometer composite BN/Cu/PDA particle consists of BN, Cu and DA in the weight ratio: 1-3:0.5-2:1-4, the grain diameter is 20-100nm, the diameter of the abrasion spot is 0.38-0.63mm, and the friction coefficient is 0.041-0.077.

2. The method of preparing a nanocomposite particle according to claim 1, comprising the steps of:

s1, adding hexagonal boron nitride into an alkali solution, performing ultrasonic treatment, centrifuging and suction filtering the solution, adding filter residues into distilled water, and stirring to obtain a turbid solution;

s2, dropwise adding the copper salt solution into the turbid solution, stirring to obtain a mixed solution, dropwise adding the mixed solution into a Tris-HCl buffer solution, adding dopamine, reacting, and performing suction filtration to obtain a target product, namely the BN/Cu/PDA nano composite particles.

3. The method according to claim 2, wherein in step S1, the mass concentration of hexagonal boron nitride after the hexagonal boron nitride is dissolved in the alkaline solution is 0.01 to 1.0 g/mL; preferably, in the step S1, the alkali solution is a NaOH solution, and more preferably, the concentration of the alkali solution is 3.0 to 6.0 mol/L.

4. The preparation method according to claim 2, wherein in step S1, the ultrasonic time is 20-35h, and the ultrasonic frequency is 20-25 KHz; preferably, in the step S1, the centrifugal rotation speed is 800-; preferably, in the step S1, after centrifugation, the supernatant is subjected to ultrasonic filtration for 5-15min and then is subjected to suction filtration, wherein the ultrasonic frequency is 20-25 KHz; preferably, in the step S1 and the step S2, the rotation speed during stirring is 200-600r/min, and the stirring time is 20-60 min.

5. The method according to claim 2, wherein the concentration of the turbid liquid in step S1 is 0.01-0.03 g/ml.

6. The method according to claim 2, wherein in step S2, the copper salt solution is CuSO₄Solution or Cu (NO)₃)₂The concentration of the copper salt solution is 0.1-0.4mol/L, the ratio of the added volume of the copper salt solution to the volume of the alkali solution in the step S1 is 1-3: 2-10.

7. The method of claim 2, wherein in step S2, the pH of the Tris-HCl buffer solution is 7.0-9.0, and the volume ratio of the buffer solution to the copper salt solution is 2-8: 1.

8. The method according to claim 2, wherein in step S2, the ratio of the amount of dopamine to the amount of copper salt solution is 0.1-0.4: 1-10 (g: mL).

9. The method as set forth in claim 2, wherein in step S2, the reaction time after adding dopamine is 12-48h, and stirring is performed at a rotation speed of 200-600 r/min.

10. Use of the BN/Cu/PDA nanocomposite particles according to claim 1 or the BN/Cu/PDA nanocomposite particles prepared by the method according to any one of claims 2 to 9 as an additive for lubricating oils.

Technical Field

The invention relates to the technical field of nano composite materials, in particular to BN/Cu/PDA nano composite particles and a preparation method and application thereof.

Background

Frictional wear is one of the most important forms of material and equipment damage and failure, and how to effectively control friction, reduce wear and improve lubricating performance becomes a problem to be solved. Boron Nitride (BN) is a typical two-dimensional nano particle, has excellent chemical stability, oxidation resistance, mechanical strength, friction reduction and wear resistance and the like due to the unique structure, is widely applied to the field of tribology, and is used as a lubricating oil additive. Copper (Cu) has excellent conductivity, corrosion resistance and antifriction and wear-resistant performance, and the existing experiments show that the base oil containing the copper nanoparticles has lower friction coefficient and wear-scar diameter, and the copper nanoparticles have good self-repairing function on the wear surface and have obvious environmental friendliness. Compared with graphene, BN has more excellent chemical stability and lower cost, and has better chemical inertness compared with metal particle nano Cu such as Ag, Al and the like. However, due to the reasons of low density of boron nitride and poor wettability with copper, the boron nitride/copper composite material is difficult to be uniformly mixed, so that the uniformity of the performance of the existing boron nitride/copper composite material is poor, for example, chinese patent document CN 111560533 a (application No. 202010444604.0) discloses a high thermal conductivity boron nitride/copper composite material and a preparation method thereof, wherein a copper salt is mixed with a boron nitride dispersion liquid and an alkali solution to perform a double decomposition reaction to obtain a reaction product, the reaction product is mixed with a reducing agent and then subjected to a heating treatment to obtain a composite, and the composite is mixed with copper powder and then subjected to a sintering treatment to obtain the high thermal conductivity boron nitride/copper composite material. There is therefore a need for a new boron nitride/copper composite particulate for use as a lubricant additive.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides the BN/Cu/PDA nano composite particles, the preparation method and the application thereof, which not only greatly improve the tribological performance of the composite particles, but also have simple steps, green and environment-friendly medium, no need of high-temperature and high-pressure treatment in the preparation process and convenience for large-scale production.

In order to achieve the purpose, the invention adopts the following technical scheme:

a BN/Cu/PDA nano composite particle comprises the following components in a mass ratio relation of BN to Cu to DA: 1-3:0.5-2:1-4, the particle size range is 20-100nm, the diameter of the abrasion spot is 0.38-0.63mm, and the friction coefficient is 0.041-0.077; the method for measuring the abrasion mark diameter and the friction coefficient comprises the steps of modifying the composite particles by oleic acid, adding the modified composite particles into liquid paraffin with the concentration lower than 2 wt%, and testing on a four-ball friction testing machine according to the test load 196-392N, the running speed 1000-2000r/m and the running time 30-60 min.

The preparation method of the BN/Cu/PDA nano composite particles comprises the following steps:

s1, adding hexagonal boron nitride into an alkali solution, performing ultrasonic treatment, centrifuging and suction filtering the solution, adding filter residues into distilled water, and stirring to obtain a turbid solution;

s2, dropwise adding the copper salt solution into the turbid solution, stirring to obtain a mixed solution, dropwise adding the mixed solution into a Tris-HCl (Tris hydrochloride), adding dopamine, reacting, and performing suction filtration to obtain a target product, namely BN/Cu/PDA nano composite particles.

Preferably, in step S1, the mass concentration of the hexagonal boron nitride after the hexagonal boron nitride is dissolved in the alkaline solution is 0.01-1.0 g/mL. Further preferably, the mass concentration of the hexagonal boron nitride after the hexagonal boron nitride is dissolved in the alkaline solution is 0.03-0.6 g/mL.

Preferably, in step S1, the alkali solution is NaOH solution, and the concentration is 3.0-6.0 mol/L. Further preferably, the concentration of the alkali solution is 4.0 to 5.0 mol/L.

Preferably, in the step S1, the ultrasonic time is 20-35h after the boron nitride is added into the alkali solution, and the ultrasonic frequency is 20-25 KHz.

Further preferably, the ultrasonic time is 28-30h, and the ultrasonic frequency is 22-24 KHz.

Preferably, in the step S1, the centrifugal rotation speed is 800-. Further preferably, the centrifugal speed is 1000-2000r/min, and the centrifugal treatment time is 3-5 min.

Preferably, in the step S1, after centrifugation, the supernatant is subjected to ultrasonic filtration for 5-15min, and then is subjected to suction filtration, wherein the ultrasonic frequency is 20-25 KHz. Preferably, the supernatant is subjected to ultrasonic filtration for 8-12min after centrifugation, and then is subjected to suction filtration, wherein the ultrasonic frequency is 21-24 Hz.

Preferably, in the step S1 and the step S2, the rotation speed during stirring is 200-600r/min, and the stirring time is 20-60 min. Further preferably, the rotation speed during stirring is 300-400r/min, and the stirring time is 30-40 min.

Wherein the stirring in the step S1 makes the hydroxylated hexagonal boron nitride uniformly dispersed in the distilled water; the stirring in step S2 allows the copper ions added to the turbid liquid to be better dispersed between the hexagonal boron nitride lamellae, and the copper is uniformly distributed on the surface of the boron nitride.

Preferably, the mass concentration of the turbid liquid in the step S1 is 0.01-0.03 g/ml. Further preferably, the mass concentration of the turbid liquid is 0.015-0.025 g/ml.

Preferably, in step S2, the copper salt solution is CuSO₄Solution, Cu (NO)₃)₂The solution or other soluble copper salt solution can be used, the concentration of the copper salt solution is 0.1-0.4mol/L, the ratio of the added volume of the copper salt solution to the volume of the alkali solution is 1-3: 2-10. Further preferably, the concentration of the copper salt solution is 0.2-0.3mol/L, and the ratio of the addition volume of the copper salt solution to the volume of the alkali solution is 1.5-2.5: 4-8.

Preferably, in step S2, the pH value of the Tris-HCl buffer solution is 7.0-9.0, and the volume ratio of the buffer solution to the copper salt solution is 2-8: 1. Further preferably, the pH value of the buffer solution is 7.8-8.5, and the volume ratio of the buffer solution to the copper salt solution is 3-6: 1.

preferably, in step S2, the ratio of the addition amount of dopamine to the addition amount of copper salt solution is 0.1-0.4: 1-10 (g: mL). Further preferably, the ratio of the addition amount of dopamine to the addition amount of the copper salt solution is 0.2-0.3: 3-6 (g: mL).

Preferably, in the step S2, the reaction time after the dopamine is added is 12-48h, and stirring with the rotation speed of 200-. More preferably, the reaction time is 15-25h, and stirring with the rotation speed of 300-400r/min is applied during the reaction.

The invention also provides the application of the BN/Cu/PDA nano composite particles as a lubricating oil additive.

The invention has the beneficial effects that:

1) the preparation method provided by the invention has simple procedures, does not need to use the complex operations of high temperature, high pressure and the like commonly used in the existing preparation method, has the advantage of environmental protection, uses simple and easily-obtained raw materials, and is convenient for large-scale production;

2) the particle size of the BN/Cu/PDA composite particles prepared by the preparation method is nano-scale, and compared with the existing material, the nano-composite particles provided by the invention further improve the dispersion uniformity and the connection performance of boron nitride and copper ions in the nano-composite particles by utilizing polydopamine, thereby effectively improving the lubricating performance, and the BN/Cu/PDA composite particles can be used as an additive to be added into lubricating oil to enable the lubricating oil to obtain good antifriction and wear-resistant performance.

Drawings

FIG. 1 is an SEM photograph of BN/Cu/PDA nano-composite particles prepared in example 1;

FIG. 2 is an XRD pattern of the BN/Cu/PDA nano-composite particles obtained in example 1;

FIG. 3 is SEM image of four-ball experimental grinding marks of the BN/Cu/PDA nano-composite particles prepared in example 1.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

The raw materials used in the examples are all common products sold in the market, and the instruments used are all common instruments in the industry.

Example 1:

a preparation method of BN/Cu/PDA nano composite particles comprises the following steps:

s1, adding 0.3g of hexagonal boron nitride (h-BN) into 30mL of 5.0mol/L NaOH solution, carrying out ultrasonic treatment in an ultrasonic cell pulverizer for 30h at the ultrasonic frequency of 21KHz, carrying out centrifugal treatment at the rotating speed of 2000r/min for 3min after the ultrasonic treatment is finished, separating and collecting supernatant, weighing 0.5g of suction filtration product after the supernatant is subjected to suction filtration, dispersing the suction filtration product into 20mL of distilled water, and stirring for 30min at 400r/min to obtain turbid liquid with the mass concentration of 0.025 g/mL;

s2, taking 5mL of prepared 0.3mol/L CuSO₄Adding the solution into the turbid solution, stirring for 30min at the speed of 300r/min to obtain a mixed solution, dropwise adding the mixed solution into 25ml of Tris-HCl buffer solution with the pH of 8.5, adding 0.25g of dopamine, stirring and reacting for 24h at the speed of 400r/min, and carrying out suction filtration to obtain the BN/Cu/PDA nano composite particles.

The BN/Cu/PDA nano composite particles prepared in the embodiment have the composition that the mass ratio relation of BN to Cu to DA is 3: 0.95: 2.5. as shown in FIG. 1, the composite fine particles obtained in this example had a particle size of 30 nm. As shown in FIG. 2, the (002), (100), (102) and (004) planes correspond to BN, and the (111) plane corresponds to nano Cu. Adding the prepared particles into liquid paraffin with the concentration lower than 2 wt.%, and inspecting the tribological performance of the particles by using a four-ball friction tester, wherein the four-ball friction tester has the following conditions: the experimental load is 392N, the running speed is 1450r/m, the running time is 30min, and as shown in figure 3, the minimum diameter of the abrasive wear marks obtained by the experiment is 0.42mm, and the minimum friction coefficient is 0.057.

Example 2:

a preparation method of BN/Cu/PDA nano composite particles comprises the following steps:

s1, adding 0.2g of hexagonal boron nitride into 20mL of 5.0mol/L NaOH solution, carrying out ultrasonic treatment in an ultrasonic cell crushing instrument for 30h at the ultrasonic frequency of 22KHz, carrying out centrifugal treatment for 4min at the rotating speed of 3000r/min after the ultrasonic treatment is finished, separating and collecting supernate, carrying out suction filtration on the supernate, weighing 0.5g of the supernate, dispersing the weighed supernate into 20mL of distilled water, and stirring for 20min at the speed of 300r/min to obtain turbid liquid with the mass concentration of 0.025 g/mL;

s2, taking 5mL of prepared 0.3mol/L CuSO₄Adding the solution into the turbid solution, stirring for 30min at the speed of 400r/min to obtain a mixed solution, dropwise adding the mixed solution into 20ml of Tris-HCl buffer solution with the pH of 8.5, adding 0.20g of dopamine, stirring and reacting for 20h at the speed of 400r/min, and performing suction filtration to obtain the BN/Cu/PDA nano composite particles.

The BN/Cu/PDA nano composite particles prepared in the embodiment have the composition that the mass ratio relation of BN to Cu to DA is 2: 0.95: 2. the composite fine particles obtained in this example had a particle size of 50 nm. Adding the prepared particles into liquid paraffin with the concentration lower than 2 wt%, and inspecting the tribological performance of the particles by using a four-ball friction tester, wherein the four-ball friction tester has the following conditions: the test load is 196N, the running speed is 1450r/m, the running time is 60min, the minimum diameter of the abrasive wear marks obtained by the test is 0.52mm, and the minimum friction coefficient is 0.053.

Example 3:

a preparation method of BN/Cu/PDA nano composite particles comprises the following steps:

s1, adding 0.5g of hexagonal boron nitride into 40mL5.0mol/L NaOH solution, carrying out ultrasonic treatment for 25 hours in an ultrasonic cell crushing instrument at the ultrasonic frequency of 20KHz, centrifuging at the rotating speed of 3500r/min for 5min after the ultrasonic treatment is finished, separating and collecting supernate, weighing 0.4g of supernate after suction filtration, dispersing the weighed supernate into 20mL of distilled water, and stirring at 400r/min for 30min to obtain turbid liquid with the mass concentration of 0.02 g/mL;

s2, taking 6mL of prepared 0.3mol/L CuSO₄Adding the solution into the turbid solution, stirring for 40min at the speed of 300r/min to obtain a mixed solution, dropwise adding the mixed solution into 20ml of Tris-HCl buffer solution with the pH of 8.0, adding 0.30g of dopamine, stirring and reacting for 18h at the speed of 300r/min, and carrying out suction filtration to obtain the BN/Cu/PDA nano composite particles.

The BN/Cu/PDA nano composite particles prepared in the embodiment have the composition that the mass ratio relation of BN to Cu to DA is 5: 1.14: 3. the composite fine particles obtained in this example had a particle size of 40 nm. Adding the prepared particles into liquid paraffin with the concentration lower than 2 wt%, and inspecting the tribological performance of the particles by using a four-ball friction tester, wherein the four-ball friction tester has the following conditions: the experimental load is 200N, the running speed is 1000r/m, the running time is 30min, the minimum diameter of the abrasive wear-marks obtained by the experiment is 0.38mm, and the minimum friction coefficient is 0.041.

Example 4:

a preparation method of BN/Cu/PDA nano composite particles comprises the following steps:

s1, adding 0.5g of hexagonal boron nitride into 20mL of 3.0mol/L NaOH solution, carrying out ultrasonic treatment in an ultrasonic cell crushing instrument for 20 hours at the ultrasonic frequency of 25KHz, carrying out centrifugal separation at the rotating speed of 1800r/min after the ultrasonic treatment is finished, collecting supernate, carrying out suction filtration on the supernate, weighing 0.2g of the supernate, dispersing the supernate into 20mL of distilled water, and stirring the solution for 60 minutes at 300r/min to obtain turbid liquid with the mass concentration of 0.01 g/mL;

s2, taking 10mL of prepared 0.2mol/L CuSO₄Adding the solution into the turbid solution, stirring for 60min at the speed of 600r/min to obtain a mixed solution, dropwise adding the mixed solution into 30ml of Tris-HCl buffer solution with the pH value of 7.5, adding 0.4g of dopamine, stirring and reacting for 12h at the speed of 600r/min, and performing suction filtration to obtain the BN/Cu/PDA nano composite particles.

The BN/Cu/PDA nano composite particles prepared in the embodiment have the composition that the mass ratio relation of BN to Cu to DA is 5: 1.27: 4. the composite fine particles obtained in this example had a particle size of 40 nm. The concentration of the prepared particles added into liquid paraffin is lower than 2 wt.%, and the tribology performance of the particles is inspected by using a four-ball friction tester, wherein the four-ball friction test conditions are as follows: the test load is 196N, the running speed is 1450r/m, the running time is 60min, the minimum diameter of the wear scar obtained by the test is 0.45mm, and the minimum friction coefficient is 0.051.

Comparative example 1

BN/Cu/PDA nano composite particle

The comparative example uses the method provided in example 1, and controls the feeding ratio, so that the prepared BN/Cu/PDA nano composite particles have the mass ratio relation of BN to Cu to DA of 5: 1.27: 4. the composite fine particles obtained in this example had a particle size of 190 nm. Adding the prepared particles into liquid paraffin with the concentration lower than 2 wt.%, and inspecting the tribological performance of the particles by using a four-ball friction tester, wherein the four-ball friction tester has the following conditions: the experimental load is 392N, the running speed is 1450r/m, the running time is 30min, the minimum diameter of the abrasive wear marks obtained by the experiment is 0.78mm, and the minimum friction coefficient is 0.125.

Comparative example 2

BN/Cu/PDA nano composite particle

The comparative example uses the method provided in example 1, and controls the feeding ratio, so that the prepared BN/Cu/PDA nano composite particles have the mass ratio relation of BN to Cu to DA of 2: 0.9: 6.7. the composite fine particles obtained in this example had a particle size of 240 nm. Adding the prepared particles into liquid paraffin with the concentration lower than 2 wt.%, and inspecting the tribological performance of the particles by using a four-ball friction tester, wherein the four-ball friction tester has the following conditions: the experimental load is 392N, the running speed is 1450r/m, the running time is 30min, the minimum diameter of the abrasive wear marks obtained by the experiment is 0.82mm, and the minimum friction coefficient is 0.103.

Comparative example 3

BN/Cu/PDA nano composite particle

This comparative example used the method provided in example 1 and controlled the feeding ratio such that the resulting BN/Cu/PDA nanocomposite particles had a composition in which the mass ratio of BN to Cu to DA was 1.5: 5.8: 0.2. the composite fine particles obtained in this example had a particle size of 230 nm. Adding the prepared particles into liquid paraffin with the concentration lower than 2 wt.%, and inspecting the tribological performance of the particles by using a four-ball friction tester, wherein the four-ball friction tester has the following conditions: the experimental load is 392N, the running speed is 1450r/m, the running time is 30min, the minimum diameter of the abrasive wear marks obtained by the experiment is 0.86mm, and the minimum friction coefficient is 0.137.

Comparative example 4

BN/Cu/PDA nano composite particle

This comparative example used the method provided in example 1 and controlled the feed ratio such that the resulting BN/Cu/PDA nanocomposite particles had a BN: Cu: DA mass ratio of 1.2: 3.8: 5.5. the composite fine particles obtained in this example had a particle size of 340 nm. Adding the prepared particles into liquid paraffin with the concentration lower than 2 wt.%, and inspecting the tribological performance of the particles by using a four-ball friction tester, wherein the four-ball friction tester has the following conditions: the experimental load is 392N, the running speed is 1450r/m, the running time is 30min, the minimum diameter of the abrasive wear marks obtained by the experiment is 0.91mm, and the minimum friction coefficient is 0.127.

By comparing the experimental results of the above experimental examples and comparative examples, the BN/Cu/DA nanocomposite particles having the mass ratio range provided by the present invention have the optimum tribological properties.

Meanwhile, compared with the prior art such as Chinese patent documents CN 111560533A and CN 109280792A, the preparation method provided by the invention does not need the complex treatment steps of high-temperature treatment or mechanical mixing and high-temperature sintering, and the prior art can only prepare the boron nitride/copper composite block material, can not prepare the boron nitride/copper nano-scale composite particles, and can not use the prepared finished product as the lubricating oil additive. The BN/Cu/DA composite particles provided by the invention are small in particle size (nanometer level), the preparation method of the composite particles is simple in steps and environment-friendly, and experiments prove that the lubricating effect of lubricating oil (namely the diameter of the grinding spot and the friction coefficient obtained in a four-ball friction experiment) can be effectively improved by directly adding the composite particles prepared by the method into the lubricating oil.